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DESIGN AND FABRICATION OF ANGULAR POST JIG
TEAM MEMBERS
T.ARUNGIRI(21809114006)B.ASWINKUMAR(21809114007)MOHAMMED RAUB(21809114028)
ABSTRACT
Based on the need for work holding devices Our project will enable operations like drilling, reaming
and tapping easier even if the job profile is angular Design and fabrication of angular post jig cover the
absolute design to the specified dimensions of the work piece .
Jig permits drilling holes in one side of the work piece with a single location and clamping operation
OBJECTIVES OF OUR PROJECT
Jig is a source which holds the job and also guides the tool
It eliminates the need for marking on the job
Even an unskilled technician can use them
Jigs are light weight ,they can be used either by fastening it with the
table or holding it in hands
INTRODUCTION GENERAL
Drilling jigs are used
To machine holes in mechanical products
To obtain positional accuracy
To locate and guide the drill, reamers etc., in relation to the work piece
Jigs prove to be economical and technically desirable
Drilling jigs makes feasible the drilling of holes at higher speeds
With greater accuracy and with less skilled labours, holes are laid out and drilled by
hands
Jigs produce interchangeable parts
DEFINITION
JIGS
Device which holds and positions the work, locate and
guides the cutting tool relative to the work piece
Not fixed to the machine table
Lighter in construction
FIXTURES
Work holding device, which holds and positions the work but
does not guide itself, locate or positioning the cutting tool.
It is usually heavy in construction.
ESSENTIAL FEATURES OF JIGS
Reduction of idle time Cleanliness Replaceable parts Hardened surface Economic soundness Easy manipulation Position of clamps Clearance Rigidity and stability Safety
GENERAL RULES FOR DESIGNING JIGS
Cost of production
Locating point and clamping arrangement
Fool-proof
Avoid complicated clamping
Provide holes
Provide clamping lugs
FACTORS TO BE CONSIDERED
Component
Capacity of the machine
Production requirement
Location
Loading and unloading arrangements
Clamping arrangements
Clearance between the jigs and components
Base frame and welded construction procedure
Tool guider and cutter setting
Rigidity and vibration
Cost
TOLERANCE AND ERROR ANALYSIS
• Limits and fits
Classification of fits
Running fit
Push fit
Press fit
Force fit
ELEMENTS OF JIGS
Jig body
Jig feet
Jig bushing
Jig plate or bush plate
Locaters
Clamps
Fool proof element
TYPES OF JIGS Template jig Plate jig Channel jig Leaf jig Pot jig Turnover or table jig Box jig or tumble jig Trunnion jig Indexing jig Post jig Sandwich jig Nut cracker jig Pump or universal jig Latch jig
DESIGN CALCULATIONS
DESIGN CALCULATION Dimension of the jig components:
1. Base plate of the jig =175 x 140 mm
2. Thickness of the base plate =10mm
3 Vertical jig plate length &Breadth, Width = 165x100x12mm
4. Top jig plate length & breadth, width =100 x100 x12
6. Angular post plate =175x100x12mm
7 .Locater outer diameter =Ø 40x20 height
8. Locater inner diameter = Ø27.5mm
DIMENSION OF THE JOB
Outer Diameter of the job =35mm
Height of the job =47mm
Inner diameter of the locator =27mm
Required diameter of the drill =8mm(No1)
DESIGN PROCEDURE OF THE ANGULAR POST JIG
SELECTION OF JIG
An Angular post jig is to be selected for making an
angular hole on Cylindrical surface required diameter=8mm
SELECTION OF BUSH
Press fit is preferred, therefore select fixed bush
with hole range diameter 8 mm.
SELECTION OF BUSH
Select bush of fixed type DDB; 5.100
The diameter to be drill the work piece is=8mm
As per design norms bush sizes (long) are
L1=20mm
L2= 16mm
D3=20mm
In our project bush dimensions are
L1=30mm
L2= 19mm
D3=26mm
SELECTION OF LOCATERS :
For side location, locater is to be
fabricated to the work piece. Locater
inner diameter is 27.5 mm that is
equal to outer diameter work piece.
Thickness of frame (t) = 10mm
Base length = 3 x length of work Piece
= 3 x 47 = 141mm
Working height (h2) = 2 x outer dia. of work piece
= 2 x 47 = 94mm
Total height of jig(ht) = 2t + h2 + bush head
= 20 + 94 + 10 = 124mm
SELECTION OF JIG BODY
DESIGN OF SCREW
Size of the screw (bolt) = M10
Pitch = 1.5mm (P.S.G. pg: 5.42)
For coarse thread dc = 8.4 mm
Stress area = 58 mm2
Initial tension in bolt P1 = 2860d = 28600N
But this, P1 =∏/4 * dc2 * ft
Tensile stress, ft = P1 / ∏/4 * dc2 = 516.05 N/ mm2
As the pin is double shear, P1 =2* ∏/4 * dc2 * ft
ft =28600*4 / 2 * ∏ *8.42 = 258.04 N/ mm2
Shear stress (fs):
As the pin is double shear
P = 2* ∏/4 * d2 * fs
Shear stress = load / area = 182.07 N/ mm2
Therefore, the design is safe.