Challenge

Week 4:- Pin Unit Design Challenge

SShivram Hulgunde29 Jun 2022

INTRODUCTION

Fundamentals of pin unit design-

It is necessary to locate car panel with two pins one pin to restrict 4 woy motion (4 transitional) and one pin to restrict 2 way motion (2 rotational)

Pin should engage 3-6 mm from cor ponal entry surface

•All pins should be accomodated with 2 way adjustable shims respective of direction of

•Round pin should be used in arresting 4 way in car panel if the hole is round aresting Round pin thould be used in arresting 2 way in car panel if the hole is slot

•Diamond pin should be used in omiting 4 way in car panel if the hole is slot

• Diamond pin should be used in arresting 2 way in car panel if the hole is round Thesis of the car panel has and the axis of the pin should be same (in general)

the pin tourance for geo pn will be 0.35 mm and for repot pin will be 0.25 mm

There are two types of pin units

1)fixed pin unit

fixed pin unit is a unit designed to the car panel using pins

2) Retractable pin unit A retractable pin unit is designed to locate the car panel using pins, but the entire pin package is mounted in the retractable cylinder the cylinder will move the unit up and down

1. Pin

It locates the car panel it can either be a make part or a standard part.

• A pin should have a grinding surface on shaft with fits onto which the pin retainer is fixed.

The mounting surface of pin should be fine machined surface It should have step machine surface to lock rotation which matches with pin retainer The mounting surface of pin retainer to the block should be machined surface

All machined planes should be perpendicular to the axis of shaft.

Pin must have fastening provision like tapped hole from bottom or a V groove from side

• A pin must be hardened (heat treatment) (55 to 60 HRC) and black oxide finished in general

• Material Hardened material like C45, 16MNCR5, 20MNCR5, EN31 etc

• Surface finish-black oxide, Zinc coating, Chrome plating

Pin Retainer:

A pin Retainer is a part which holds the pin in position, the pin retainer can either be a make part or a standard part also. Example for a make pin retainer: (50)

• Pin retainer should have a hole with a fit, on to which the pin will be fixed. The pin mounting surface of the pin retainer should be a fine machined surface.

• The pin mounting surface of the pin retainer should have a step to lock the rotation of the pin.

• The mounting surface of the pin retainer to the blocks should be a machined surface.

• The pin retainer will be fixed to a block or a L block to the riser with 2 dowel holes (pins) and at least with one screw hole to maintain the tolerance.

Block/L Block:

These parts are mainly used to accommodate the shimming directions as per fundamental in general. Also in some cases used for other design feasibility.

Shims / Spacers:

Shims and spacers are some standard parts in general, which are used for adjustments of locators (NC Blocks and Pin retainers) for obtaining the desired values for the precise working of a unit with respect to car part. In general to adjust the Design to manufacturing deviation.

Blade:

Blade is part like a plate, which connects the parts of a unit to a riser. In general the blade can be either a make part or a standard part.

Riser:

Riser is a part on which all the parts of a unit are mounted, and is mounted on the base plate of a tool. In general the riser can either be make part or a standard part.

Dowel holes and machined surfaces:

All make parts which are to be assembled with tolerance should be designed with 2 dowel holes and at least of 1 to 6 threaded / free hole(depends on size). And to be fine machined for the mounting surface with 3 to 5 mm step machining.

DESIGN METHODOLOGY

INPUT;

This is a surface body for which we have to prepare BIW Fixture

thickness of part of 1mm

we have placed two locating pins in the two circular holes one pin is circular aresting four transalation of the wp

and another pin is diamond arest two ratational motion of the WP

1) Fixed pin unit;

We have designed two lived pin units these units consist of pin pin retainer block blode, mer shimpacks

As we know all the parts should have atleast two dowel hore and one screw hole, this will ensure in good assembly of parts

we have given shimming in two directions

Thefixed pin units are locating the surface body of the WP

2 . RETRACTABLE PIN UNIT ;

. we have designed two retractable pin units . one is for single rod cylinder and other is for dual rod cylinder

. these units consists of pin, pin retainer, block, riser, cylinder, shames.

• From the below images we can see the open and close position of the rods in the retractable by pin units

• In retractable pin unit

1, the circular pin is directly mounted on the rod of the cylinder, and the actuating motion of the cylinder the rod will retract up and down. In retractable pin unit

2, the diamond pin along with the pin retainer, block and blade is mounted to the two rods of cylinder, by the actuating motion of the cylinder the rod will move up and down.