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* GB785243 (A) Description: GB785243 (A) ? 1957-10-23 Method of conditioning web-like materials in a closed chamber Description of GB785243 (A) PATENT SPECIFICATION 785,243 Date of Application and filing Complete Specification: July 7, 1955. Application made in Sweden on July 8, 1954. Complete Specification Published: Oct 23, 1957. No 19634155. Index at Acceptance:-Class 96, A( 2: 7 B 24) International Classification:-D 2 If g. COMPLETE SPECIFICATION Method of Conditioning Web-like Materials in a Closed Chamber. We, AKTIEBOLAGET SVENSKA FLAKTFABRIKEN, a Swedish joint-stock company, of Kungsgatan 18, Stockholm, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - The present invention relates to a method of cond tonin R web- like
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* GB785243 (A)

Description: GB785243 (A) ? 1957-10-23

Method of conditioning web-like materials in a closed chamber

Description of GB785243 (A)

PATENT SPECIFICATION 785,243 Date of Application and filing Complete Specification: July 7, 1955. Application made in Sweden on July 8, 1954. Complete Specification Published: Oct 23, 1957. No 19634155. Index at Acceptance:-Class 96, A( 2: 7 B 24) International Classification:-D 2 If g. COMPLETE SPECIFICATION Method of Conditioning Web-like Materials in a Closed Chamber. We, AKTIEBOLAGET SVENSKA FLAKTFABRIKEN, a Swedish joint-stock company, of Kungsgatan 18, Stockholm, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - The present invention relates to a method of cond tonin R web-like ialcrials in a closed chamber by means of a gaseous medium containing water vapour When conditioning web-like hydroscopic materials said 1 5 treatment is mainly provided for causing the moisture ratio of the material to balance with normal storing atmosphere For special kinds of paper such a conditioning is furthermore necessary with respect to the demands for stability during printing or the like The conditioning can be performed in several ways, for instance by supplying finely divided moisture by means of spray nozzles or by conducting the web through a space with a water vapour atmosphere. In the first case there will often occur difficulties in distributing the moisture evenly and there will also be a risk of stains or marks on the surface of the material In conditioning in a water vapour atmosphere 30there is a risk for occurrence of marks due to a partial condensation Furthermore, there are difficulties in carrying out the

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conditioning without an undesired rise of temperature The best method of conditioning hitherto known is held to be the method in which the material is caused to pass through a closed space, where the material is exposed to the influence of wet air of suitable moisture ratio This method howeverowing to the rise of temperature by condensation of moisture in the material and to the resulting reduction of the relative humidity of the air-necessitates a rather long treatment time It is an object of the present invention to eliminate said drawbacks. In the present invention the conditioning is divided into a number of separate effective treatment steps and the material is cooled between said steps to a lower temperature than the temperature prevailing in the pre 50 ceding treatment step The method is characterized in that the relative humidity of the conditioning medium in the separate effective treatment steps is maintained at differentiated and successively increasing values to 55 wards the last treatment step, and in that the material between said treatment steps is cooled to different temperatures determined by the temperature in the preceding treatment step 60 Other characteristics of the method will be evident from the following description and the appended claims. In the accompanying drawings: Fig 1 illustrates a diagram for the hygro 65 scopic equilibrium, for instance for paper. Fig 2 is a vertical longitudinal section through a conditioning apparatus suitable for the performance of the method; and Fig 3 is a vertical transverse section 70 through said apparatus. In Fig 1 the curves A and D represent the state of equilibrium for a material having a moisture ratio indicated in the ordinate in relation to the surrounding air, having a 75 relative humidity indicated in the abscissa. A is the so-called absorption curve, i e the curve showing that equilibrium moisture ratio which a material reaches when being moistened and D is the desorptioin 80 curve, i e the curve showing that equilibrium moisture ratio which a material reaches when being dehumidified P, represents the moisture ratio to which the material in accordance with the 85 invention should be moistened to reach a moisture ratio P in equilibrium with normal atmosphere after the material in the last treatment step has been dehumidified. The distance 0-Pl thus illustrates the moist 90 785,243 ening period and the distance P,-P 2 illusrates in corresponding manner the deFiumidifying period. In Figs 2 and 3, 1 designates the entering part of the web-like material, 2 3 and 4 designate a number of vertical parts of the web which leaves the apparatus at the point 1 l 1 The outer walls of the apparatus are designated 5 and the apparatus is divided by means of

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partitions 10 into a number of zones I, II, III, and IV 7 a and 7 b respectively designate the upper and the lower rolls for the web 6 a and 6 b designate distributing means for the supply of the conditioning medium which means are arranged between the different runs of the web The supplying means are in the instance shown oval shaped tubes and equipped with a longitudinal slot 8 along the upper side of the tube which slot is covered by a deflector plate 9 arranged at -some distance from the gin' 13 deqsivnates a perforated intermediate bottom arraneed below the lower rolls 7 b 12 desipnates a space below said bottom, which is used for the discharge of the conditioning medium Said space 12 is connected by means of the openings 14 to a channel 20 situated outside the apparatus, in which channel means for preparing and circulation Of the conditioning medium are arranged in the form of spray nozzles 17 and a circulatin R fan 16 having a motor 15 In the channe T 20 eliminator nlates 18 Dreventinc water from being carried with the gaseous medium into the treating chamber proper and a heat exchanaer 19 are further arranged The channel 20 is connected bv means of the branch ducts 21 and 22 to the above mentioned distributing means 6 a 6 b 23 designates the roof of the apparatus which roof in the instance shown is arched for the purnose of causing drots of liquid forming bv condensation to be discharged towards the sides of the apparatus. In the apparatus shown in Figs 2 and 3 it is Dresumed that cooling takes place by bringing the web in contact with a gaseous conditioning medium of a suitable low temnerature The web is moistened in sections so I HI and so on and is cooled in sections II, TV and so on of the apparatus All the sections are of the same kind Tf the cooling is to be carried out by direct contact of the web with a cooled surface, the web should be conducted over cooled rolls between the 55 different sections These rolls can be placed above and below the apparatus or within the same, in which latter case they are shielded from the rest of the space In direct cooling with rolls all the sections 1, 11 III and i V 60 will be effective treatment steps.

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* GB785244 (A)

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Description: GB785244 (A) ? 1957-10-23

Improvements in or relating to engines incorporating poppet valves

Description of GB785244 (A)

PATENT SPECIFICA Tl ON 7859244 Date of filing Complete Specification: June 27, 1956. Application Date: July 13, 1955 No 20349155. Complete Specification Published: Oct 23, 1957. Index at Acceptance:-Classes 7 ( 6), B 2 P( 2 K 2 A: 2 K 2 D:12: 13); and 122 ( 2), B 15 A 2. International Classification:-F Olg F 02 f. COMPLETE SPECIFICATION. Improvements in or relating to Engines Incorporating Poppet Valves. We, ALBION MOTORS LIMITED, a British Company, and GEORGE HERBERT LEE, of British nationality, both of the Company's address at Scotstoun, Glasgow, W 4, Scotland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- 10) This invention relates to engines incorporating poppet valves. According to the invention a valve mechanism for an engine incorporates at least one poppet valve member operatively connected to a cam by means including a pull rod coupled to a sliding member presenting an abutment engageable with the end of the stem of the valve member, and the sliding member is slidable on a fixed pin the axis of which is parallel to the axis of the stem of the valve member. A compression spring may be provided to act against the sliding member, said spring being located diametrally opposite the associated valve in relation to said pin, said spring and the valve spring providing a balanced thrust on the sliding member. The end of the pin remote from the cylinder head may be supported, e g said end of the pin may engage a socket in a bell-shaped cap member the rim of which is bolted to the cylinder head, the sliding member and the stem of the valve member being thus enclosed The end of the pull rod remote from the sliding member may be pivoted to the free end of a radius rod, said radius rod being arranged to receive a lateral

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thrust from a cam. The end of the pull rod in engagement with the sliding member may present a spherical face, e g it may carry a washer formed with a spherical face engaging a spherical seat in the sliding member whereby to compensate for lateral movement of the pull rod lPrice 3 s 6 d l while the radius rod changes its angular position. The accompanying drawing is a vertical section through one embodiment of a valve mechanism of an internal combustion engine according to the invention. In the drawing, 1 denotes a cylinder head, and 2 denotes a poppet valve member engaging a seat presented by the cylinder head 1, the valve member 2 being urged towards the seat by the spring 3 4 denotes a pin screwed into the cylinder head 1, and 5 denotes a sliding member slidable on the pin 4 and presenting an abutment 6 engageable with the end of the stem of the valve member 2 7 denotes a cam rotatable by the mechanism of the engine and engageable with a lateral face of a radius rod 8 swingable about a fixed pivot 9 The free end of the radius rod 8 is engaged with one end of a pull rod 10 the other end of which penetrates a projection 11 on the sliding member 5. The pull rod 10 is fitted with nuts 12 and a spherical washer 13 engaging a correspondingly shaped depression in the projection 11. 14 denotes a balancing spring bearing against the projection 11 and serving to balance the thrust of the valve spring 3 15 denotes a cap fastened to the cylinder head 1 The end of the pin 4 remote from the cylinder head engages a socket in the cap 15 and is supported by the cap 15. In practice, as the cam 7 rotates it exerts a lateral thrust on the radius rod 8 which swings about its pivot 9 and the tensile stress generated in the pull rod 10 causes the pull rod to pull the sliding member 5 along the guide pin 4 towards the cylinder head 1, the abutment 6 coming against the end of the stem of the poppet valve member 2 whereby to move the poppet valve member 2 to its open position in opposition to the valve spring 3 Both springs 3 and 14 are compressed When the lobe of the cam 7 moves out of engagement with the radius rod 8 the 785,244 valve spring 3 closes the valve, the sliding member 5 being pushed in the direction away from the cylinder head by the action of the valve spring 3 and the balancing spring 14.

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* 5.8.23.4; 93p

* GB785245 (A)

Description: GB785245 (A) ? 1957-10-23

Improvements in or relating to mechanism for presenting rotation of a firstmember relative to a second member, e.g., in a displacement indicator

Description of GB785245 (A)

COMPLETE SPECISCANON Improvements in or relating to Mechanism for presenting Rotation of a First Member relative to a Second Member, e.g., in a Displacement Indicator. We, GIDDINGS & LEWIS MACHINE TOOL COMPANY, a corporation organised under the laws of the State of Wisconsin, United Siatvs of America, of Fond du Lac, Wisconsin, United SLates of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to mechanism for preventing rotation of a first member relative to a second member, both members being rotatable about a common axis. The invention has many applications, one of which is indicators for measuring and showing the displacements, either linear or angular, of movable elements and finds, for example one advantageous use as a micrometer indicator of the position of a translatable tool holder or work support in machine tools. The invention may also be applied to dial indicators having a concentric scale and vernier dial rotated in timed relation so that coarse and fine displacements may be observed. The present invention provides a mechanism for preventing rotation of a first member relative to a second member, both members being journalled for rotation about a common axis and said mechanism comprising, in combination, a counterweight member journalled for rotation about a common axis gear means interconnecting the second member and said counterweight member for causing rotation of one in the opposite direction when the other is rotated relative to the first

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member, said gear means including at least one gear formed union the second member at a point radially displaced from the common axis, said counterweight member having a moment of inertia proportioned to the moment of inertia of the second member in the same ratio as the mechanical advantage afforded by said gear means. When applied to an indicator of the foregoing type the vernier dial may be quickly and easily indexed to any desired rotational setting relative to a rotatable shaft. In such an indicator there is provided a dial rotatable either with or relative to a rotary shaft, selected rotational settings of the dial relative to the shaft being maintained notwithstanding inertia forces arising upon acceleration or deceleration of the shaft by means counterbalancing and neutralizing such inertia forces. In this aspect, there is provided an arrangement of general utility by which a first member, journalled for rotation relative to a second rotatable member, is held in fixed angular relation to such second member without the necessity of any mechanical clamps; yet in which the first member may be manually indexed relative to the second member. This obviates the releasing of clamps prior to, and the tightening of such clamps subsequent to, such indexing of the first member, as necessary in prior devices wherein the attendant possibility of disturbing the indexed positions was present. In such a displacement indicator there is provided a scale which is rotated in timed relation to a vernier dial by differential gearing and in which a reference index member, concentrically disposed between the scale and dial to facilitate reading of both is held stationary solely by engagement with such differential gearing. The invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a front elevation of a displacement indicator embodying the features of the invention: and Fig. 2 is a sectional view of the indicator, taken substantially along the line 2-2 in Fig. 1. While the invention has been shown and s described in some detail with reference to a particular embodiment thereof, there is no intention that it thus be limited to such details. On the contrary, it is intended here to cover all alterations" modifications and equivalents falling within the scope of the invention as defined by the appended claims. Referring now to the drawings, the exemplary displacement indicator here shown is intended for use in measuring or indicating either the linear displacement of a translatable member (not shown) or the angular displacement of a rotatable member (not shown). It includes a

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first member adapted to be rotated through angles proportional to the displacements of the movable member, such first member being here illustrated as a stub shaft 10 journalled by means of a suitable bearing 11 in a housing 12 (partially shown) of the equipment with which the indicator is employed. For imparting rotation to the stub shaft 10, it may be equipped at its inner end with a bevel gear 14 which may be drivingly engaged with a rotatable member. For measuring or indicating fine increments of displacement, the stub shaft 10 carries a second member or vernier dial 15 which is rotatable with the stub shaft yet angularly adjustable relative to it in order to afford manual setting or indexing of the dial. The dial 15 is scribed with suitable graduations which may be read opposite an index mark 16 on a stationary index member of ring I8. For indicating relatively coarse increments of displacement, a scale 19 S con- nected by means of differential gearing to be rotated in timed relation to the dial 15 and shaft 10. the scale also having graduation marks on a portion thereof which may be read opposite the index mark 16. Frorn the foregoing it will be seen that the dial 15 is rotatably driven with the shaft 10 at a greater rate than the scale i9, so that the dial laps the scale much in the manner as the minute hand of a clock laps the hour hand. It may be pointed out that indicators of this general type are commonly employed own machine tools to show the location and displacement of a feedable work-carrying or tool-carrying member, such as the saddle on a vertical turret lathe. In such machines the saddle is linearly translatable by means of a feed screw which ch is rotatably driven by any suitable feed dive mechanism. The feed screw may carry bevel gear (not shown) drivingly engaged. with the gear 14 on the stub shafts 10 so that the latter shaft is rotated in proportion to linear displacement of the saddle. - By way of illustration in the present case, the scale 19 is calibrated in inches between major graduations on its face and fifths of an inch between minor graduations, the total travel of the saddle being, say, thirty-nine inches. During a complete traverse of the saddle the scale makes approximately one complete revosuction. Also, the vernier dial 15 may be calibrated in thousandths of an inch, having two hundred such calibration marks around its face so that the nearest one-fifth of an inch may be read from the scale 19 and the nearest thousandth of an inch then read from the dial 15. While the indicator shown has been described by way of example as measuring and indicating the linear dis placement of a machine tool element. it will be understood that with the calibration on scale 19 and dial 15 changed, such an indicator may also be employed to show total and incremental revolutions of a rotatable member.

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In displacerent indicators of the type described it is cften necessary to translate the movable elenent a predetermined distance from any position. While it is possible to read the scaie and dial and add cr subtract such distance from the initial reading ;n order to determine what tile final reading should be, the dial 15 is preferably rotatable relative to the shaft 10 so that it may be indexed to zero and the new displacement read directly. Heretofore, after such indexing, it has been necesary to mechanically clamp the dial to the stub shaft 10 in order to prevent relative rotation of the two due to inertia forces ont eh dial orising as the stub shaft 10 is subi@@tedto acceleration or deceleration. The use of such mech@@ical cl@@@ping means involved not only a compley and initially expensive mechanis@@, but further created the problem of assuring that the indexed settings of the dial relative .o the shaft were not disturbed when the clamping means were loosened or tightened. It is to the total elimination of this dif?-i- culty that the present invention is directed. In accordance with one feature of the inmention, means are provided for mounting the dial 15 for rotation either with or relative to the shaft 10, such means preventing the shifting of the dial relative to the shaft under the influence of inertia forces, eft permitting the dial to be manually indexed relative to the shaft. all without the neces- sity of mechanical clamping means. In carrying out the invention. a counter-weight member 20 is iournalled for rotation relative to the shaft 10 and connected by gear means to rotate the dial 15 i!l one direction when the counterweight is rotated in the opposite direction relative to the shaft 10. As here shown, the shaft 10 is formed with an end flange 21 against which a ring 22 and a flange 24 bear in an axial direction. the latter two being rigidly locked to the shaft by a key 25. The dial 15 is niade annular n shape and journalled concentrically around the ring 22, presenting its calibrated face to clear view. The rear edge of the dial is formed with an internal gear 26 to co-operate with the counterweight member 20 in the manner described below. The counterweight member 20, in this instance, includes a disk 28 having a central knob portion 29 rigidity mounted on a shaft portion 30 which is journalled within a coaxial recess 31 defined in the outer end of the shaft 10. The shaft portion 30 is held in axial position by means of a crescent key 32 inserted through a radial slot 34 in the shaft 10, the shaft portion 30 being biased against the key 32 by a compression spring 35 disposed at the inner end of the recess 31. A pinion 36 is formed intecrally on the shaft portion 30 for a atirnose explained below. For connecting the dial 15 and counterweight 20 to rotate in opposite

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directions relative to the shaft 10, an idler gear 38 is journalled on a pin 39 carried between the flange 24 and the ring 22, the gear 38 being meshed with the pinion 36 and the internal gear 26 on the dial 15. To index the dial 15 relative to the shaft 10. therefore. it is only necessary for an operator to grasp the knob portion 29 and manually turn the same in either direction. As a result, the dial 15 is driven in the opposite direction through the pinon 36 idler gear 38 and internal gear teeth 26. Byvirtue of the me chapical advantage afforded by the idler gear connection the dial 15 is rotated at a much slower rate than the counterweight 20 so that it is possible to set accurately any selected one of the dial calibration marks opposite the index mark 16. In order to prevent rotation of the dial 15 relative to the shaft 10 as the latter is subjected to rotational acceleration, the moments of inertia of the dial 15 and the counterweight 20 are proportioned in the same ratio as the mechanical advantage afforded by the idler gear connection therebetween. That is. the disk 28 is formed and weighted with the other Darts of the counterweight member 20 so that the moment of inertia of the tattler when multiplied by the mechanical advantage of the idler gear connection is equal to the moment of inertia of the dial 15. When the shaft 10 is subiected to acceleration or deceleration. both the dial 15 and counterwei(rht 20 will tend to rotate in the same direction relative to the shaft 10 due to inertia forces. However. because the idler gear 38 tends to drive the dial and counterweight in opposite directions, the inertia forces oppose and counterbalance one another. Thus, with- out any clamping means whatever, both the dial 15 and counterweight 20 are held stationary relative to the shaft 10. The index 18 is annular in shape and concentrically supported in slidable relation around the dial 15. The scale 19 is also annula@ and, in turn, concentrically disposed in slidable relation around the index ring 18. Thus, the ring 22, dial 15, index ring 18, and the scale 19 are all disposed in concentrically nested relation as shown. For driving the scale in timed relation to the dial 15 and shaft 10, in this case, at a greatly reduced rate, differential gearing is operatively connected between the shaft 10 and the scale. The problem arises, however, of holding the index ring 18 absolutely stationary. It is highly desirable that the index ring be concentrically disposed between the scale and dial in order that the graduations of the latter two may be read directly opposite the index mark 16. But. in such case, there is little possibility, short of bulky or expensive arrangements, of anchoring the index ring fast to the housing 12.

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In accordance with another aspect of the invention, means are provided in the displacement indicator not only for driving the dial 15 and scale 19 in timed relation, but also the holding the index ring 18 stationary, solely through engagement of the latter with the differential gearing employed. As here shown, the differential gearing includes a sun gear 40 fast on the shaft 10 (and therefore rotatable with the dial 15), the tear 40 being secured against rotation relative to the shaft by the key 25. A plurality of floating pinions 41 are disposed in meshed relation around the sun gear 42 held fast on the housing 12 by suitable bolts 44. The scale 19 is formed at its inner edge with an internal gear 45 which is also meshed with the floating pinions 41, being disposed axially alongside of the stationarv gear 4'. The scale gear 45 is formed with at least one more tooth than the stationary gear 42, so that for each revolution of the sun pinion 40, the scale 19 is rotated through an angle equal to the angular extent of its extra teeth. In the arrangement illustrated, the scale gear 45 may have two snore teeth than the stationary gear 42, the angular position of its two extra teeth being equal to one minor calibration on the scale face. Therefore, for each revolution of the vernier dial 15, the scale will rotate through one minor graduation increment, indicative of 1/5 of an inch. A very great reduction ratio is thus obtained for driving the scale 19 in timed relation to the dial 15. For holding the index ring 18 stationary. it is formed at its inner edge with an internal ring gear 46 which is also meshed with the floating pinions 41, being disposed axially alongside the scale gear 45. The index ring gear 46 is provided with exactly the same number of teeth as the stationary gear 42. As a result, when the scale 19 is rotatably driven, the index ring 18 cannot move. Rather, it is held absolutely stationary although not anchored to the housing 12 and restrained only by its engagement with the pinions 41. The entire assembly as thus described may be held in place by spring means. For this purpose, flanged cup members 48 are inserted in each of the floating pinions 41, the latter being annular in form. 13alls 49 are disposed in the cup members and biased against the flange 24 by compression springs 50. As a result, the flange 24 and ring 22 are biased axially to the right (Fig. '') against the integral shaft flange 21. At the same time. the flanges of the cup members 48 bear against the index ring 18 biasing the latter, as well as the scale 19 axially to the left against the face of the stationarv gear 49. The floating pinions 41 are thus held axially in engagement with the

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stationary gear 42, and the integral gears 45 and 46 are held axially in meshine entao--e- ment with the floating pinions. From the foregoing, the operation of the illustrated displacement indicator is believed to be clear. By way of brief summary, it may be observed that rotation of the shaft 10 serves to carry the vernier dial 15 with it so that position of the shaft mav be readily observed by referring to the graduation marks on the dial opposite the index mark 16 on the stationary index ring 18. By virtue of the differential gearing described, the scale 19 is rotated in timed relation, at a greatly reduced rate, to the dial 15 so that relatively great increments of displacement may be read from the graduation marks on the scale face opposite the index mark 16. Because the scale gear 45 has at least one more tooth than the stationary gear 49. the scale is driven at a greatly reduced rate. Yet, because the pear 46 on the index ring 18 has exactly the same number of teeth as the stationary gear 42, the index ring is held absolutel" stationary. This Dermits the index ring 18 to be concentricallv disposed between the scale 19 and dial 15. Graduations on both the scale and dial may therefore be read directly opposite the index mark 16. The arrangement is extremely compact because it is not necessary to anchor the index ring 18 directly to the housing 12 in order to hold it stationary. To adjust the angular position of the dial 15 relative to the shaft 10, it is only necessary to turn the counterweight member 20 by grasping the knob 29. This results in the dial being turned in the opposite direction at a greatly reduced rate relative to the shaft 10 by virtue of the reversing connection provided by the idler gear 38. At any time, therefore, the position of the dial 15 may be accurately adjusted relative to thz index mark 16 to provide a new reference. Because the moments of inertia of the counterweight 20 and dial 15 are balanced through the idler gear connection, it is not necessary to mechanically clamp the dial 15 to the shaft 10 as the latter is subjected to acceleration or deceleration. The dial is held absolutely fixed in rotational position relative to the shaft because the inertia forces or torques arising in the same direction on the counterweight 20 and dial 1' balance and cancel one another through th reverse gearing connection afforded by the idler gear 38. What we claim is: 1. A mechanism for preventing rotation of a first member relative to a second member, both members being journalled for rotation about a common axis and said mechanism comprising, in combination. a counterweight member journalled for rotation about the common axis, gear means interconnecting the second member and said counterweight member for causing rotation of one in the opposite direction when the other is rotated relative to the first member.

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said gear means including at least one gear formed upon the second member at a point radially displaced from the common axis. said counterweight member having a moment of inertia proportioned to the moment of inertia of the second member in the same ratio as the mechanical advantage afforded by said gear means. 2. The mechanism according to Claim 1. wherein the moments of inertia of said counterweight member and said second member are proportioned in the same ratio as the mechanical advantage afforded by said gear means, whereby rotation of said second member relative to said first member is prevented when the latter is subjected to rotational acceleration but said second member may be rotatably indexed relative to said first member. 3. A mechanism for preventing rotation. of a first member relative to a second member, wherein said first member comprises a shaft rotatable through angles proportional to the displacements of a movable member and said second member comprises an indexable dial journalled for rotation relative to the shaft, a counterweight member also journalled for rotation relative to the shaft, gear means interconnecting said dial ann counterweight member such that rotation of the latter in one direction relative to the shaft turns the former in the opposite direction, said dial and counterweight member having their moments of inertia balanced whereby inertia forces on the dial and counterweight member cancel each other to hold them stationary relative to the shaft as the

* GB785246 (A)

Description: GB785246 (A) ? 1957-10-23

Improvements in or relating to magnetic chucks or clamping devices andmethods of manufacturing such devices

Description of GB785246 (A)

PATENT SPECIFICATION Date of Application and filing Complete Specification Aug 9, 1955. Application made in Switzerland on Aug 12, 1954. Application made in Switzerlandon Nov 29, 1954.

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Complete Specification Published: Oct 23, 1957. 785,246 No 2293555. Index nt Acceptance:-Class 100 ( 2), P 16 N( 2: 3: 4: X). International Classification -B 41 n. COMPLETE SPECIFICATION Improvements in or relating to Magnetic Chucks or Clamping Devices and Methods of Manufacturing such Devices. 1, ALFRED EMIL HERZER, a Swiss citizen, of 68, Scheideggstrasse, Zurich, Switzerland, do hereby declare the invention, for which 1 pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention is concerned with improvelnents in or relating to magnetic chucks or clamping devices and methods of manufacturing said devices. Different magnetic clamping or tensioning devices have been known so far, in which instead of electro magnets, permanent magnets have been used These permanent magnets are arranged in such a way between a bottom plate and a pole plate that upon moving said permanent magnets the attractive force of the pole plate can be made effective or ineffective. These known clamping devices have the disadvantage that the magnetic system adheres to the pole plate with very great force so that considerable force is necessary to nlove the magnets Besides, this form of construction requires a certain play in the magnetic system between the pole plate and the bottom plate in order to facilitate a shifting of the magnetic system Thus the pole plate may be subject to bending when loaded which would limit the accuracy of working of the clamped work pieces. Magnetic clamping devices have been used for other purposes than for the tightening or clamping of work pieces Thus it was suggested for instance to provide plane carriers for printing surfaces with a magnetizable base, in order to attach said printing surface carriers to the printing mechanism of the printing machine by means of magnetic clamping devices Particularly for the last named purpose clamping devices with a small height and high attractive power for especially thin sheets, are indispensible Furthermore, the clamping device has to be of such construction that ieliminates every possibility of bending. Furthermore it was also suggested to attach flexible carriers for printing surfaces, which are at least partly magnetizable, to 50 the printing element of the printing machine by means of magnetic cylinders Such a magnetic cylinder, as well, has to possess the aforementioned characteristics. All magnetic cylinders proposed so far 55 for this purpose had to be

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energized electrically Such magnetic cylinders possess the great disadvantage that, when the current is interrupted, severe accidents may occur, since on account of the high speed of 60 the carrier for the printing surface, when the magnetic attractive power fails, such carrier would be thrown off from the cylinder with great force. Usually magnetic clamping devices for 65 working elements have only a relative small clamping surface while the necessary surfaces for the clamping of carriers for printing surfaces have to be much larger For instance, cylinder surfaces for copper plate 70 printing up to two square meters are not unusual. Permanent magnetic clamping devices and magnetic cylinders with such surface dimensions cannot be manufactured by the 75 methods hitherto used since the forces necessary for moving the magnetic system become so great that this cannot be accomplished by the usual means Besides, the construction of a device with such a large 80 surface, if all conditions have to be met, is only possible at extraordinary expense The magnetic clamping device according to this invention overcomes these disadvantages. According to this invention there is pro 85 vided a magnetic chuck or clamping device comprising a base at least one outer surface of which is formed as a work holding surface and having one or more longitudinally extending bores of circular cross see-90 (Price 3/6) T' 1, c1 785,246 tion therethrough, a rotatable magnet assembly in said bore(s) consisting of at least 3 ne flat bar permanent magnet mounted in non-magnetic guiding means of circular z cross section which engage the walls of the bore(s) and ensure that an air gap of uniform width all round said bore is provided for the pole faces of the magnet and means for rotating said magnet assembly engaging at least one end thereof. The clamping device preferably comprises one or more grooved recesses formed in a ferromagnetic base and communicating with said bore(s) into which recesses similarly shaped ferromagnetic parts can be inserted These parts are connected to the base by means of non-magnetic material in such a way that with the exception of their bearing surfaces contact between these parts and the base is avoided After such a connection is established, bores are provided in the base parallel and symmetrical to the longitudinal axis of the inserted parts in such a way, that the inserted parts form a part of the bore wall and a work holding surface with magnetically insuated attracting parts of alternating polartv is obtained, the attracting pole of one polarity being formed by the basic body itself. The accompanying drawings show different preferred embodiments of clamping de:-ices according to the invention, as well as parts thereof.

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Fig I is a perspective view illustrating Nhe ferromagnetic basic body after the first -.-orking phase; Fig 2 is a similar view illustrating the 0 samne element after the second working phase, Fig 3 shows perspective views illustratsuggested constructional forms of ferromagnetic parts for insertion into the basic body; Fig 4 is a perspective view illustrating the basic body with the parts according to Fig 3 inserted; Fig 5 is a perspective view illustrating ohe basic body with the parts inserted and the intermediate space filled with a nonmagnetic material and also pole bores provided for the insertion of the permanent -magnet with the first pole bore at the left shown empty, while the two other bores are provided with a magnet each, the middle one being in the magnetically operative position and the one at the right in the inoperative position, Fig 6 is a partial diagrammatic view illustrating the course of the magnetic lines of force when the pole plate is operative: Fig 7 is a similar view illustrating the course of the magnetic lines of force when the pole plate is inoperative; Fig 8 is a perspective view illustrating a clamping device with two pole plates independently positioned opposite each other; Fig 9 is a perspective view illustrating a guiding cylinder with apertures for the in-70 sertion of the magnets; Fig 10 illustrates a longitudinal section taken on line B-B of Fig 9; Fig 11 is a perspective view illustrating a center part for the permanent magnet: 75 Fig 12 is a similar view illustrating a further centering part; Fig 13 illustrates a perspective view of the coupling of several magnets by means of guiding or coupling parts: Fig 14 is a partial perspective view illustrating a center arrangement on a permanent magnet, Fig 15 is a longitudinal section of a coupling piece according to Fig 13, 85 Fig 16 is a front view of the part according to Fig 15; Fig 17 illustrates a partial longitudinal section of a coupling arrangement accord-90 ing to Fig 13: Fig 18 is a front elevational view illustrating a device for transposing magnets for the purpose of rendering the magnetic clamping flow in the pole plate operative or inoperative. Fig 19 is a section taken along line A-A of Fig 18; Fin 20 is a perspective view illustrating a magnetic cx linder for the clamping of 100 mannetisable and flexible carriers for printing surfaces: Fi: 21 is an end view illustrating a device for transposing the magnets for rendering the clamping flow of the pole plane of a magnetic cylinder operative and inoperative; and Fig 22 is a partial end view illustrating a further embodiment of an arrangement for rendering the clamping flow in the pole 1 lo plane of a magnetic cylinder operative or inoperative; Fig 23 illustrates a further embodiment of a base after the first working phase:

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Fig 24 illustrates the same base after the 11 second working phase; Fig 25 shows a comb-like formed pole part: Fig 26 is a cross section according to Fig 25 taken along line C-C, 12) Fig 27 illustrates the base after insertion of the pole parts. In the various views similar reference characters indicate like parts. In the ferromagnetic base 1 of Fig 1,125 which preferably consists of soft steel or soft iron, with an alloying addition as for instance cobalt, if desired or necessary, grooved recesses 2 to 2 "'" are provided parallel to the longitudinal axis by means of 130 milling, planing or in any desired way The 785,246 number of these recesses depends on the Aimensions and the fineness of the pole di.;iun of the clamping or tightening device. In Fig 2 the same base is illustrated after the second working phase Parallel to the width axis there are provided grooved hollows 3, 3 ' and 3 " which are not as deep as the recesses 2 to 2 "". Fig 3 illustrates three similar ferromagnetic insertion pieces These pieces consist of a flat bar 4 with laterally arranged comb-like teeth 5 to 5 " ", which are disposed symmetrically on each side of said bar These three parts 4 together with the described base 1 form the work holding surface The thickness of these parts 4 corresponds to the depth of the hollows 3 to 3 " while their other dimensions are such that with the exception of the bearing surface of parts 4 on the bottom of hollows 3 to 3 " there is no contact between parts 4 and plate 1. Fig 4 is a view of the base after insertion of bars 4 The open intermediate spaces of the hollows 3 to 3 " are then filled with a non-magnetic material, as for instance soft solder, synthetic resin, etc, whereby these parts are at the same time connected firmly with the base. In the clamping plate prepared in this say, pole boles 6, 6 ', and 6 " are formed Wiei C, are parallel to and symmetrical with the longitudinal axis of parts 4 and which serv? to receive permanent magnets The thickness of the inserted parts 4 is such that they form a part of the wall of the bores 6, 6 ' and 6 ". Fig 5 shows the basic body with the inserted parts after provision of the bores 6, 6 ' and 6 " While the first pole bore 6 is shown empty, the other two pole bores 6 ' and 6 " are each provided with an energizing magnet 7 and 8 The position of magnet 7 causes the path of the lines of force to render the adjacent area of the work holding surface operative, while the position of the magnet 8 is such that the path of the lines of force due to the presence of non-magnetic material between base 4 and plate 1, follows a course within the base so that this part of the work holding surface is rendered inoperative with the attracting poles of one magnetic polarity formed by the base

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itself. The path of the lines of force is illustrated in Fig 6 when the work holding surface is operative and in Fig 7 when it is inoperative. Fig 8 illustrates a further embodiment of 6 O the tightening or clamping device according to the invention This device is different from that described with reference to Figs 1 to 7 For instance the insertion pieces 9 to 9 "" are formed as straight bars. Therefore, the base is only provided with grooved recesses extending in one direction, into which these flat bars can be inserted. W Vith the exception of the bearing surface, the inserted parts are again free of any contaci with the base and are connected by 70 nicais of a diamagnetic material to 'the base Af Ler forming the pole bores, the inserted parts 9 to 9 " ", which are magnetically insulated from the base, form a part of the walls of the bores 75 This embodiment furthermore is provided with two clamping planes, which are independent of each other and are directed opposite to each other, and which are each rendered operative by their own magnetic 80 system The lower clamping plane, made operative by magnets 10 to 13, which are preferably separately movable, is provided for clamping the device magnetically onto a machine tool, while the upper clamping 85 device serves to receive the work. Guiding means for the magnets are provided so that the magnet can easily be shifted from one position to another in the pole bores 90 Usually for small clamping devices a bearing supporting the magnets at their two ends is sufficient For a larger width of the clamping device it is necessary to use several short partial magnets for each pole 95 bore, in order to prevent a bending of the magnets by the insertion of guiding and connectins; narts This bending can arise in a longer magnet through the a tractive powers between the magnet poles and the 100 bore wall. For manufacturing reasons also the use of several, coupled magnets is preferred, since there is a practical limit to the length of magnets which can be made 105 Fig 13 is a perspective view of several magnets connected to one another The flat magnets 18, 19 and 20, the poles of which are directed vertically to the longitudinal axis of the magnets and are rounded 11 o accordingly, are provided at each end with recesses 21, which are provided for the insertion of centering means The construction of such a centering part is illustrated for example in Fig 11 The prismaticll S head 23 is shaped so as to fit, without play, into the recesses 21 of the magnet 20, and it is provided with a bolt 22 which is inserted into the centering bore 23 ' (Fig 15) of a guiding and coupling part 24, 24 ' sol 20 that the magnet is held concentrically in the coupling parts This coupling part 24, which is shown in Fig 15 in longitudinal section, and in Fig 16 in front view,

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consists of a cylinder which is provided at each 125 end with a radial slit 25, 25 ', the width of which is such that the flat magnet fits into it without having any play The diameter of the cylinder is slightly larger than the diameter of the polar circle of the magnets, 130 785,2-46 but approximately equal to the diamneter of the bore, which receives the magnets By this means a direct contact of the magnetic poles with the parts of the bore is avoided. All of these guiding and coupling parts are manufactured from non-magnetic material, instead of the centering part according to Fig 11 a centering cylinder 25, as illustrated in Fig 12, can be used as well In lthis case the ends of the magnets 18 are provided with bores, as illustrated for example in Fig 14 This centering pin 26 again fits into the bore 23 ' of the coupling part shown in Figs 15 and 16. For small clamping devices, where only one magnet is provided for each bore, guiding parts on each end of the magnet are provided by means of which, similarly to the coupling parts the magnets are guided concentrically in the bore These guiding parts are also provided on both the outermost ends of the magnets when coupling together several nmagnets The arrangement of the magnets with a coupling vasrt and a guiding part is shown in Fig 17 in lon,_it'udinal section The magnets 18 an-l 19 are connected to each other by the coupling part 24 in the aforementioned wav, while the guiding part 27 of the magnet 19, 30the centering arrangement of which corresponds to that of the coupling part 24, is provided with a cylindrical attachmlent 28 which fits into the bore of a bearing plate which covers the magnet receiving bores of the clamping device The guiding part 27 furthermore is provided with means 29 for the insertion of a tool for shifting the magnet, by means of which the magnetic flow for the clamping action can be made operative or inoperative. instead of guiding and coupling parts for holding the individual magnets concentrically in the pole bores, guiding cylinders vwith suitable perforations for the insertion Of the magnets can be used as well. An embodiment of such a guiding cylinder is shown in Fig 9, while Fig 10 illustrates a longitudinal section on the line B-B of Fig 9 The guiding cylinder 57 cono sisting of non-magnetic material is provided with slit-like perforations 58, 59 and 60, arranged symmetrically to a central axis The guiding cylinder embodied in the drawingz is used for the insertion of three magnets. But it can be constructed for any other desirec number of magnets as well The beginning and end of the guiding cylinder are broken off in the drawing, but they correspond to the construction of the guiding 0 and coupling parts. Magnet 20 inserted into the perforation 58 is provided with a recess

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21 for the insertion of a centering part A corresponding recess is provided as well on the part of 65the magnet which is not shown Guiding er 57 is provtke _ tac and at the end of its perforations 58, 59 an: i;:) wth transversely directed and preferabl: s,;uare-shaped bores a, b c and d, which are provided for the insertion of siinilarlv 70 sha pd centering bars By means of these entering bars the magnets are secured in the perforations of the cylinder Of course, these bores can be circular if desired In this case the diameter of the centering cv-75 finder has to be equal to the width of th L recess 21 in the magnet. Usually it is preferred that switchin, mechanism is provided by which all magnets are shifted simultaneously Such a 80 switching arrangement is shown in Fig EI partly diagrammatically and in Fig 19 in a cross section on the line A-A of Fig 18. On the extension 28 of the guiding par' 27 (Fig 19) is mounted a toothed wheel 31 85 of non-magnetic material This wheel i F in gear with the two racks 33 and 3 + alse of non-mriagetic material Gear wvheels 3 C and 32 connected to the guiding parts of ahe emaillmn agnets, al e also in resh 90 -.illi these rack bars By rotating or shiftmia gie magnet 19 and the wheel 31 connected to said magnet, the rack bars and the remainfin gy wheels cause the other magnets also to be shifted 95 A cross-section of Fig 18 on line A-A. is sh Ov-n in Fig 19 The said rack bars move in similarly shaped guiding parts consisting of ron-maginetic material which are screwed to the basic body by means of 100 an end piece 35 of non-magnetic material. When wheel 31 rotates both rack bars move until the end stop Their length is such that the magnets can be shifted through an angle of 90 degrees For very wide clamp 1 D 5 i-ng devices it might be advantageous to provide a magnet shifting device on both sides of the basic body. Fthe 20 shows a magnetic cylinder for the clamping of magnetizable and flexible 110 carriers for printing surfaces The arrangement of the poles on the surface of the magnetic cylinder is the same as that in Fig '. Into the massive metal cylinder which replaces the basic body in this case, axially 115 and circumferentially extending grooved recesses are formed into which, similar to the clamping device according to Figs 1 to F. ferromagnetic parts 36 to 36 "" with comblike teeth, as illustrated in Fig 3, are in 120 serted These parts are connected with the rotatable basic body of the magnetic cylinder by means of non-magnetic material. Since the inserted parts are flat, they 125 partly protrude from the

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surface of the cvlinder By turning or grinding, these parts can be reduced to the diameter of the cvlinder. In this magnetic cylinder also, the cir-130 ese wheels 46 to 46 "" are connected with the individual magnetic guiding parts. These Maltese wheels, have two stop arcs 47 and 48, and are furthermore provided with the switching grooves 49, with which 70 the actuating pin 54 of the switching device 53 co-operates Switch wheel 51 provided with a toothed rim 50, is arranged concentrically on the cylinder axis This switch wheel is provided with an arcuate 75 hollow 52, the diameter of which corresponds to that of the Maltese wheel, and facilitates the rotation during the switching operation. Toothed wheel 55 meshes with toothed 80 rim 50 of the wheel 51 and a recess 56 of wheel 55 is used for the insertion of a shifting tool When turning the switching wheel 51 clockwise, all magnets are shifted successively After a complete rotation of 85 the wheel, the wheel is stopped, since the pin 54 will rest on the back side of the Maltese wheel When turning in the opposite direction, the magnets are again shifted successively and after a complete rotation, 90 i.e when all magnets are again directed in one direction, stoppage occurs again. In a further embodiment according to the invention the mounting of the pole bars to the base is made easier by the fact that the 95 recesses in the base which are arranged parallel to the mechanical axes of the magnets as well as the central bar of the comblike shaped pole bars are provided with a dovetail shaped cross section, the dovetail 100 shaped central bar of the pole bars being smaller than the corresponding opening in the base, so that after insertion of the pole bars into the base said parts are connected tightly to each other by two strips each of 105 which consist of non-magnetic material and which are inserted into the space between the parts. Such an embodiment is shown in Figs. 23 to 27 110 The base 61 illustrated in Fig 23 is provided with two dovetail shaped recesses 62 and 63 The number of these recesses is chosen as an example only and can vary according to the size of the clamping de 115 vice Similar forms of recesses and the assembly of the clamping device as described below can be provided as well on the magnetic cylinder. Fig 24 is a view of the base 61 after the 120 second working phase The cross slits have the same depth as the longitudinal slits. Fig 25 illustrates a pole bar with comblike teeth which are provided on the left and right side of the central bar 64 A cross 125 section of this pole bar along line C-C is shown in Fig 26 The median bar 64 is provided with a lower part 65 which has a dovetail shaped cross section, while between the individual teeth the median bar 130 cumferential and axial hollows are of different depth Otherwise the

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manufacturing processes for this magnetic cylinder are completely similar to those of the desS cribed embodiments of the clamping devices according to Figs 1 to 5. After the insertion of the parts 36 to 36 " ", symmetrical and parallel to the longitudinal axis of these parts, magnet receiving bores are provided in the rotatable body in which are placed the magnets in the manner described. The magnetic cylinder is mounted on an axis 37 Flange parts 38 and 39 close the magnetic cylinder at its ends Into these parts which also consist of nonmagnetic material such as brass, stainless, nonmagnetic steel or other suitable material, the shifting devices for the magnets are installed One embodiment of such a shifting device is illustrated in Fig 21 On the guiding parts of the magnets in this device, as shown in Fig 21, gear wheels are mounted These wheels 40 to 40 " "'" are in gear with the fixed toothed rim 42. Wheel 43 is arranged concentrically with the cylinder axis 37 which is provided with a toothed rim segment 44 This wheel also is in gear with the magnet gear wheels 40 to 3040 " ' Upon turning the shifting wheel 41 which meshes with the toothed segment 44, all magnets of the cylinders can be shifted simultaneously The shifting angle of the wheel is terminated by the stopping device This angle is proportioned so that a shifting of the angle of about 90 degrees can be achieved. Thin and flexible carriers for printing surfaces which for copper plate printing for instance consist of a copper plated foil, can only seldom be clamped completely plane by means of simultaneously making all the magnets operative and inoperative This arises from the fact that the foil when being tensioned on the magnetic cylinder immediately adheres at all contacting points, so that small unevenesses occur on account of the penetration of the air between cylinder and foil or on account of small tension deformations of the foil itself, and this cannot be straightened out easily because of the adhesive or attraction forces. This disadvantage can be eliminated by a further step It consists in a stepwise operation of the magnetic forces A partial view of a device in which the particular zones pertaining to the individual magnets are successively made operative is illustrated in Fig 22 For the simplification of the illustration all pertinent parts unnecessary for the understanding of the mode of operation are omitted. In this device instead of the gear wheels 40 to 40 " "'" of Fig 21, so-called Malt785,246 785,246 has the same width throughout its whole cross-section as illustrated in Fig 27. As mentioned already, the dovetail shaped part of the median bar is smaller than the corresponding opening in the base, so that when the pole parts 65 are inserted Mnto the body 61, there remains a space

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between the two parts into which the nonmaagnetic strips 66, 67, and 68, 69 (Fig 27) are inserted Thus the pole bars are connected tightly to the base 61 and the remaining space is filled with a non-magnetic material. It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the process, form, construction and arrangement of the parts without departing from the scope of the invention, the forms hereinbefore described and illustrated in the drawings being merely preferred embodiments thereof.

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* GB785247 (A)

Description: GB785247 (A) ? 1957-10-23

Improvements in or relating to cassettes for use with magnetic recordingand/or reproducing apparatus and to such apparatus in combination with saidcassettes

Description of GB785247 (A)

AMENDED SPECIFICATION Reprinted as amended under Section 8 of the Patents Act, 1949. PATENT SPECIFICATION 7859247 Date of Application and filing Complete Specification: Aug 12, 1955. No 23292155. Application made in Germany on Aug 14, 1954. Complete Specification Published: Oct 23, 1957. Index at acceptance:-Class 40 ( 2), D 3 A 2, D 3 G 1 (A: B: C: D: E), M.

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International Classification:-Gl Oj. COMPLETE SPECIFICATION Improvements in or relating to Cass'ettes, for use' with Magnetic Recording and/or Reproducing Apparatus and to such Apparatus in combination with -anid Cassettes We, TELEFUNKEN G M B H, a company organised under the laws of Germany, of Sickingenstrasse 71, Berlin NW 87, Western Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to cassettes for use with magnetic recording and/or reproducing apparatus and to such apparatus in combination with said cassettes, which cassettes are (; the type designed to' contain an elongated magnetic recording medium such as a tape or wire and are constructed so as to be removable as a unit from said apparatus This form cf cassette will be designated hereinafter as " a cassette of the type referred to " There have been many prior proposals concerned with cassettes of the type referred to. For example, it is known to provide in the cassette a pair of reels so arranged that when the cassette is placed in operative position in suitable magnetic recording and/or reproducing apparatus, the reels are coupled to driving spindles whereby the elongated recording medium may be wound from one reel to' the other, but in order to drive the recording medium longitudinally at a substantially constant speed during recording or reproducing operations it has generally been necessary to provide a driven capstan shaft in said apparatus together with means such as a pressure or " pinch " roller to press the recording medium against the periphery of the capstan shaft. The main object of the present invention is to provide an improved cassette of the type referred to whereby the operation of the magnetic recording and/or reproducing apparatus is considerably simplified. Accordingly the invention provides a cassette of the type referred to containing a supply reel and a take-up reel, wherein said reels are rotatably mounted with their axes in spaced parallel relation by means of a carrier which is so supported in said cassette as to be capable of both angular and translational movements to move said reels in directions transverse to their axes, spring means being arranged to urge said reels towards one and the same side of said cassette. The invention also provides magnetic recording and/or reproducing apparatus in combination with a cassette as specified in the preceding paragraph, said apparatus incorporating at least one driving roller so arranged that when said cassette is placed in operative position in said apparatus contact is established between said driving roller and the outermost convolution of a magnetic recording medium wound on said

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takeup reel, and said contact is maintained by said spring means so that rotation of said roller causes longitudinal movement of said recording medium whereby said medium is unwound from said supply reel and wound on to said take-up reel. In order that the invention may be clearly understood and readily carried into' effect, one example thereof will now be described with reference to the accompanying drawings, in which:Figure 1 is a,plan view of a cassette according to the invention, and Figure 2 is a perspective view of magnetic recording and/or reproducing apparatus with the cassette of Figure 1 in operative position. Referring to Figure 1, the cassette 1 which , 7 a, is preferably made of transparent material such as methyl methacrylate, is generally rectangular in plan with rounded corner and it takes the form of a shallow box-like structure, the top wall of which is held in position by four screws The cassette 1 contains a supply reel 3 and a take-un reel 2 each of which cormprises a hub preferably without side flanges. Reels 2 and 3 are rotatably mounted with their axes in spaced parallel relation by means of a carrier 4 comprising a pair of spaced parallel plates each of which has the shape of a parallelogram although said plates could be cruciform Each of said plates has a stub shaft 5 extending perpendicularly therefrom, and the shafts 5 are arranged to co-operate with slots or grooves 6 provided in the ton and bottom walls of the cassette 1 Thus the carrier 4 is supported in the cassette 1 so as to ne capable of both angular and translational movements by means of pin and slot or pin and groove connections and the total depth of the carrier 4 is made only slightly less than the spacing between the top and bottcm walls of the cassette 1 so that the carrier 4 can move angularly and slide laterally thereby to move the reels 2 and 3 in directions transverse to their axes, and the afrangemernt is such that tilting of the carrier is substantially prevented. Spring means coupled to the carrier 4 is arranged to urge the reels 2 and 3 towards one and the same side of the cassette 1 which in the illustration of Figure 1 is the left-hand side In the present example a closed spring 7 approximately in the form of an ellipse s attached by means of a clamping member 8 to the cassette 1 at a position remote from the left-hand side thereof, and the spring 7 bears against a pin 9 which emtends between the plates forming the carrier 4 so as to impart rigidity thereto It will be seen from Figure 1 that the respective points at which the spring is coupled to the cassette 1 and to the carrier 4 lie substantially on the minor axis of the spring 7 Fixed abutments 10 and 11 vvhich may have a facing of friction material such as felt, are provided in the cassette 1, and with an elongated magnetic recording tape 22 wound on the reels 2 and 3 as

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shown, the spring 7 functions to urge the outermost convolutions of the wound tape 22 against the abutments 10 and 11 respectively, so as to prevent undesired unwinding of the tape 22 when the cassette 1 is not in operative position. It should be noted that when the tape 22 is wound almost-conipletely on to reel 2 or reel 3, the wound tape 22 extends between dhe plates forming the carrier 4 and may extend beyond the centre thereof so that it is preferable not to employ a continuous shaft passing through the carrier 4 instead of the two stub shafts 5 for movably supporting the carrier 4 in the cassette 1. The magnetic recording and/or reproducing apparatus with which the cassette 1 is intended to co-operate, comprises a pair of spaced stops 12 and 13 between which are positioned a driving roller 14 and at least one magnetic transducing head When the cassette 70 1 is moved into operative position in the direction indicated bv arrow 21 until the left-hand side of the cassette engages the stops 12 and 13, roller 14 makes contact with the outermost convolution of the tape 22 wound on reel 2 75 and thereafter reel 2 is moved bodily by virtue of sliding movement of the carrier 4 so that the reel 2 is carried clear of the abutment 10. Under these conditions the spring 7 functions to maintain contact between the roller 14 and 80 the tape 22 wound on reel 2 so that clockwise rotation of roller 14 will effect longitudinal movement of the tape 22 from reel 3 to reel 2 across a guide surface 16 at a speed substantially equal to the peripheral speed of roller 14 83 If only one driving roller is provided the tape 22 wound on reel 3 remains in contact with abutment 11 so as to tension the portion of tape 22 which extends from reel 3 to reel 2. However, it is preferred to provide a further 90 driving roller 15 for co-operation with reel 3 so that as the cassette 1 is moved into operative position reel 2 is also moved bodily whereby it is carried clear of abutment 11 Apart from providing means to tension the tape 22 95 during its forward movement in the direction of arrow 23, the roller 15 may also be driven in an anti-clockwise direction when it is required to rewind the tape 22 on to the supply reel 3 Preferably either or both of the rollers 100 14 and 15 are provided with flanges so as to ensure that the tane 22 winds evenly on to the reel 2 or reel 3 as the case may be, and An order that the depth of the cassette 1 can be kept to a minimum it is provided with recesses 105 or apertures 24 for the reception of the driving rollers 14 and 15. Preferably 'the apparatus contains two magnetic transducing heads 17 and 18 arranged between rollers 14 and 15 in a position 110 make contact with the portion of the tape 22 which runs across the surface 16 One of the heads serves as a combined recording and reproducing

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head whilst the other functions when required as an erasing head Between 115 the heads 17 and 18 is provided an electric contact in the form of a roller 19 for a purpose to be described. The apparatus shown in Figure 2 comprises a closed box-like housing 25 and in contradis 120 tinction to conventional arrangements the housing is not provided with any form of hinged lid which requires to be raised in order to operate the apparatus The front wall of housing 25 is provided with a rectangular 125 recess into which the cassette 1 can be pushed into operative position, and to facilitate manipulation of the cassette 1 a portion 20 thereof approximately midway along the right hand side as viewed in Figure 1 is shaped and 130 785,t 47 in said reels are rotatably mounted with their axes in spaced parallel relation by means of a carrier which is so supported in said cassette as to be capable of both angular and translational movements to move said reels in direc 70 tions transverse to their axes, spring means being arranged to urge said reels towards one and the same side of said cassette.

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