ISSN (Print): 2321-5747, Volume-1, Issue-1, 2013

129

Design and Dynamic Analysis of an Automatic

Tool Changing Mechanism used in VMC

M. B. Vaghela, V. J. Savsani & S. B. Jadeja

B. H. Gardi College of Engineering & Technology, Rajkot,

Pandit Deendayal Petroleum University, Gandhinagar,

E-mail : manoj0085@gmail.com, vimal.savsani@gmail.com, sbjadeja@gardividyapith.ac.in

Abstract - Design analysis of high speed automatic tool

changing mechanism for high speed machines like VMC,

and minimize tool changing cycle time as compare with

current used ATC. To get the result of displacement,

velocity, acceleration at every connecting point for tool

changing cycle time 2s by using mechanism module in

Creo Parametric 1.0 software. By dynamic analysis get the

results for acceleration at every connecting point in tool

changing mechanism. Main goal of this paper is find out

total force applied at every connecting points with consider

total mass of component and also consider relative force

applied at point from getting acceleration result from the

dynamic analysis of tool changing mechanism in Creo

parametric 1.0 software. With getting this total applied

force, do the FEA for critical component of tool changing

mechanism and as per that result if possible than redesign

the component ant try to reduce the tool changing cycle

time.

Keywords - ATC: Automatic Tool Changer, Creo Parametric

1.0, Dynacam 10, Dynamic Analysis, FEA: Finite Element

Analysis, Motion Analysis, Tool Changing Mechanism, and

VMC: Vertical Machining Centre.

I. INTRODUCTION

Today’s fast growing automatic manufacturing

process; to develop high speed automatic machine is a

very challenging task for that required to develop high

speed tool changing mechanism with minimum tool

changing cycle time for VMC type of machine.

Tool changing mechanism of ATC for VMC type of

machine having simultaneously two types of motion

which is occurred at shaft, downward and upward

motion and rotary motion of shaft. For downward and

upward motion of shaft used radial cam and for rotary

motion of shaft used globoidal cam. To design and

analysis of radial cam used graph [8] of arm downward

and upward movement versus cam rotation angle and

for globoidal cam used graph [8] of arm rotating chart

versus cam shaft rotation angle with the help of

Dynacam 10 software [10]. To design and develop high

speed tool changing mechanism, do the design and

analysis of some critical components like radial cam,

globoidal cam [1] and take existing design of shaft and

linkage mechanism from the company [9] and also

design the other components which is required for make

a complete assembly of tool changing mechanism of

ATC [1]-[2].

ATC with using Creo Parametric 1.0 software and

to get the results of displacement by position analysis,

velocity by kinematic analysis and acceleration by

dynamic analysis for each defined connecting points

with using mechanism module of Creo parametric 1.0

software. Compare result of displacement of shaft with

actual required movement and from the result of

dynamic analysis got the result for acceleration, with

using acceleration result find the total applied force at

each define connecting point.

II. DESIGN AND ANALYSIS OF CAMS

In tool changing mechanism of ATC two motions

which is occurred at shaft, downward and upward

motion of shaft and rotary motion of shaft. For

downward and upward motion of shaft used radial cam

and for rotary motion of shaft used globoidal cam.

A. Design and Analysis of Radial Cam

To design and analysis of radial cam used Dynacam

10 software [10] and graph of arm downward and

upward movement versus cam rotation angle[8].Radial

cam design for maximum displacement 115 mm. From

Dynacam 10 software getting results of displacement,

velocity, acceleration and jerk for each degree 0° to

360° and also get cam profile of radial cam. Based on

International Journal on Mechanical Engineering and Robotics (IJMER)

ISSN (Print): 2321-5747, Volume-1, Issue-1, 2013

130

this cam profile prepare solid model of radial cam [4]

using Creo Parametric 1.0 software as shown in “Fig.

1”.

Fig. 1 : Radial cam

B. Design and Analysis of Globoidal Cam

To design and analysis of globoidal cam used

Dynacam 10 software [10] and graph of arm rotation

angle versus cam rotation angle [8]. From Dynacam 10

software getting results of displacement, velocity,

acceleration and jerk for each degree 0° to 360°. Prepare

solid model of globoidal cam using Creo Parametric 1.0

software as shown in “Fig. 2”.

Fig. 2: Globoidal cam

III. DESIGN OF TOOL CHANGING

MECHANISM OF ATC

To design final tool changing mechanism assembly

[3] of ATC make a design of radial and globoidal cam

[5] and take existing design of shaft, linkage from

company [9] and also design other components required

to make an assembly using Creo Parametric 1.0

software. Prepare design of final tool changing

mechanism assembly of ATC in Creo Parametric 1.0

software as shown in “Fig. 3”.

Fig. 3 : Tool changing mechanism of ATC

IV. MOTION ANALYSIS

In Creo Parametric 1.0 software powerful

mechanism module is given for motion analysis. There

can be prepare mechanism assembly [3] as per

connecting joint and motion; also do the analysis for

position, kinematic, dynamic, static and force balance

and measure definition for position, velocity,

acceleration, connection reaction, net load and may

more in mechanism module. Do the motion analysis [6]

of tool changing mechanism of ATC for position,

kinematic and dynamic analysis for tool changing cycle

time 2 s.

A. Position Analysis

For position analysis using Creo Parametric 1.0

software, after completion of final assembly of tool

changing mechanism select analysis definition type

position in mechanism module and run the analysis for

tool changing cycle time 2 s. To measure the position of

each connecting point, select measure results graph type

measure versus time and measure definition type

position in mechanism module and get the results of

displacement for each connecting point as shown in

“Fig. 4”.

Fig. 4 : Displacement chart of Tool Changing

Mechanism

International Journal on Mechanical Engineering and Robotics (IJMER)

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Get the result of displacement at shaft 114.95 mm

which is very much nearest value as per required

displacement 115 mm for upward and downward

movement of shaft.

B. Kinematic Analysis

For kinematic analysis using Creo Parametric 1.0

software, select analysis definition type kinematic in

mechanism module and run the analysis for tool

changing cycle time 2 s. To measure the velocity of each

connecting point, select measure results graph type

measure versus time and measure definition type

velocity in mechanism module and get the results of

velocity for each connecting point as shown in “Fig. 5”.

Fig. 5: Velocity chart of Tool Changing Mechanism

From the kinematic analysis of tool changing

mechanism of ATC for tool changing cycle time 2 s,

maximum velocity obtain 1638.76 mm/s at both the end

point of arm.

V. DYNAMIC ANALYSIS

For dynamic analysis using Creo Parametric 1.0

software, add the En24 material [7] to each component

of tool changing mechanism assembly and define

gravity, direction and magnitude to simulate the

gravitational force and select analysis definition type

dynamic in mechanism module and run the analysis for

tool changing cycle time 2 s. To measure the

acceleration of each connecting point, select measure

results graph type measure versus time and measure

definition type acceleration in mechanism module and

get the results of acceleration for each connecting point.

By dynamic analysis using Creo Parametric 1.0

software get the acceleration at following points.

A. Acceleration at Arm-1

Point arm-1 is a connecting point of yellow color

arm and green color tool as shown in “Fig. 3”. From

dynamic analysis of tool changing mechanism for tool

changing cycle time 2 s, result of acceleration at arm-1

get as shown in “Fig. 6”.

Fig. 6 : Acceleration at Arm-1

B. Acceleration at Arm-2

Point arm-2 is a connecting point of yellow color

arm and red color tool as shown in “Fig. 3”. From

dynamic analysis of tool changing mechanism for tool

changing cycle time 2 s, result of acceleration at arm-2

get as shown in “Fig. 7”.

Fig. 7 : Acceleration at Arm-2

C. Acceleration at Shaft

Shaft point is a connecting point of arm and shaft as

shown in “Fig. 3”. From dynamic analysis of tool

changing mechanism for tool changing cycle time 2 s,

result of acceleration at shaft get as shown in “Fig. 8”.

International Journal on Mechanical Engineering and Robotics (IJMER)

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Fig. 8 : Acceleration at Shaft

D. Acceleration at Link1-1

Link1-1 point is a connecting point of pink color

link2 and yellow color link1 as shown in “Fig. 3”. From

dynamic analysis of tool changing mechanism for tool

changing cycle time 2 s, result of acceleration at link1-1

get as shown in “Fig. 9”.

Fig. 9 : Acceleration at Link1-1

E. Acceleration at Link1-2

Link1-2 point is a connecting point of shaft and

yellow color link1 as shown in “Fig. 3”. From dynamic

analysis of tool changing mechanism for tool changing

cycle time 2 s, result of acceleration at link1-2 get as

shown in “Fig. 10”.

Fig. 10 : Acceleration at Link1-2

F. Acceleration at Link2-1

Link2-1 point is a connecting point of pink color

link2 and green color link3 as shown in “Fig. 3”. From

dynamic analysis of tool changing mechanism for tool

changing cycle time 2 s, result of acceleration at link2-1

get as shown in “Fig. 11”.

Fig. 11 : Acceleration at Link2-1

G. Acceleration at Link2-2

Link2-2 point is a connecting point of pink color

link2 and yellow color link1 as shown in “Fig. 3”. From

International Journal on Mechanical Engineering and Robotics (IJMER)

ISSN (Print): 2321-5747, Volume-1, Issue-1, 2013

133

dynamic analysis of tool changing mechanism for tool

changing cycle time 2 s, result of acceleration at link2-2

get as shown in “Fig. 12”.

Fig. 12 : Acceleration at Link2-2

H. Acceleration at Link3-1

Link3-1 point is a connecting point of radial cam

and green color link3 as shown in “Fig. 3”. From

dynamic analysis of tool changing mechanism for tool

changing cycle time 2 s, result of acceleration at link3-1

get as shown in “Fig. 13”.

Fig. 13 : Acceleration at Link3-1

I. Acceleration at Link3-2

Link3-2 point is a connecting point of pink color

link2 and green color link3 as shown in “Fig. 3”. From

dynamic analysis of tool changing mechanism for tool

changing cycle time 2 s, result of acceleration at link3-2

get as shown in “Fig. 14”.

Fig. 14 : Acceleration at Link3-2

VI. RESULT DISCUSSION

From dynamic analysis do in Creo Parametric 1.0

software gets the result of acceleration at each

connecting point of tool changing mechanism of ATC

for tool changing cycle time 2 s, as shown in “Fig. 15”.

Fig. 15: Maximum Acceleration at each point of Tool

Changing Mechanism

From the dynamic analysis of tool changing

mechanism of ATC for tool changing cycle time 2 s,

maximum acceleration obtain 59068.7 mm/s2 at link1-2

and link2-1.

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VII. CONCLUSION

Due to lengthy analytical calculation used Creo

Parametric 1.0 powerful software for position, kinematic

and dynamic analysis. By position analysis obtain very

close displacement at shaft of tool changing mechanism,

actual displacement is 115 mm and by position analysis

obtain 114.95 mm displacement at shaft. So deign of

tool changing mechanism proper.

Obtain the maximum acceleration at each

connecting point of tool changing mechanism of ATC

by dynamic analysis in Creo Parametric 1.0 software.

With this acceleration result get the total force at each

connecting point and with this total force and define

proper constraint do the finite element analysis. After

concluding the FEA result can be optimize the design of

component and tool changing mechanism.

VIII. REFERENCES

[1] “Cam Design and Manufacturing handbook”,

Robert L. Norton, Pearson Education.

[2] “Theory of Machine and Mechanisms”, Joseph E.

Shighley, Oxford Uni. Press.

[3] Wen-Tung Chang and Long-Iong Wu, “Tolerance

analysis and synthesis of cam-modulated

linkages”, Elsevier Science Ltd, Mathematical

and Computer Modeling, Vol. 57, 2013, pp.641-

660.

[4] Sun Jianping and Tang Zhaoping, “The

Parametric Design and Motion Analysis about

Line Translating Tip Follower Cam Mechanism

Based on Model Datum Graph”, Elsevier Science

Ltd, Procedia Engineering 23, 2011, pp.439 –

444.

[5] Zongyu Chang, Changmi Xu, Tongqing Pan, Lei

Wang and Xichao Zhang, “A general framework

for geometry design of indexing cam

mechanism”, Elsevier Science Ltd, Mechanism

and Machine Theory, Vol. 44, 2009, pp. 2079–

2084.

[6] Owen Butler, Buddhi Paranamana, William

Powers and Arvind Srinivasan, “Project report on

Design of a servo driven, adjustable pick and

place mechanism”, Worcester Polytechnic

Institute, 2011.

[7] “Machine Tool Design Handbook”, Cmti, The

McGraw-Hill.

[8] Manual of “Pragati Automatic Tool Changer

4020 V”, http://www.pragati-automation.com.

[9] Jyoti CNC Automation Pvt. Ltd., Rajkot,

http://www.jyoti.co,in.

[10] Dynacam 10,

http://www.designofmachinery.com.