Challenge

Week 4:- Pin Unit Design Challenge

TTushar Rastogi24 May 2022

CATIA

AIM: Designing of the fixed pin unit and retractable pin unit for fixing of panel using CATIA SOFTWARE.

THEORY OF PIN:

Pin unit consists of Pin, Pin retainer, L Block, Shims, Blade and Riser.

Further it is classified into two types:

a)- Fixed Pin unit.

b)- Retractable pin unit.

1- Pin: It is used to fix the car panel by arresting DEGREE OF FREEDOM of car panel.

There are four cases arise due to the different combination of hole and pin.

a)- Circular hole with circular pin. ----------- 4 DOF arrested.

b)- Circular hole with diamond pin.---------- 2 DOF arrested.

c)- Slot with circular pin.---------- 2 DOF arrested.

d)- Slot with diamond pin.--------- 4DOF arrested.

2)- Pin retainer: It is used to support the pin.

3)- Shims : Due to the deviation in the diemension because of Man, machine and materials we provide shim pack in order to correctly locate the pin in the hole of the respective panel.

4)-Blade : It gives you the flexibility to use the same riser for different heights of the hole positions.

5)- Riser : It is a component used to support all the other component and it is attached to the base.

Types of pin unit

Fixed pin unit: Here pin is fixed because of the pin retainer and riser.

Retractable pin unit : Here we provide any mechanism for up and down motion of pin.

Design consideration of pin

1- It is must to use two pin to locate the car panel, one pin is going to arrest 4 translational motion and another pin is going to arrest 2 translational motion of the car panel.

2- Pin must be protuding 3 to 5 mm from the hole diemension.

3- Depending on the shape of the hole we have to use specific shape of the pin to arrest 4 translational motion first and then arrest 2 translational motion of the car panel.

4- Axis of hole and axis of pin must coincide.

Manufacturing consideration of the pin

a) The mounting surface of the pin should be finely machined i.e, mounting surface of the pin should be smooth.

b) Pin must have a step collar with surface exactly match with the wall of pin retainer to arrest the rotation about the axis of the pin.

c) A pin must be hardened ( Heat treated ) and Black oxide finished in general.

d) Pin must have the provision like tapped hole from the bottom or a v groove from the side.

Tolerance of pin

a) Geo pin -0.15mm.

b) Respot pin -0.28mm.

Fixed pin unit design images

a) With T riser