Week 4:- Pin Unit Design Challenge

DESIGN OF FIX PIN AND RETRACTABLE PIN UNIT

The fix pin and the retractable pin units are hole constraining fixture for car panels.

FIXED PIN UNIT

Fixed pin unit is a unit designed to locate the car panel using pins.

The parts of fixed pin are:

1. Pin
2. Pin retainer
3. Shim/Spacer
4. Block
5. Blade or Adapter plate
6. Riser

RETRACTABLE PIN UNIT

A retractable pin unit is a unit designed to locate the car panel using pins,but the entire pin package parts will be mounted on the retractable pneumatic cylinder.

Types of retractable pin:

• 1.Single rod
• Double rod

FUNDAMENTAL OF PIN UNIT

• It is necessary to have two pins to locate a car panel.One pin must arrest 4 ways( 4 translational) and the other must arrest 2 ways ( 2 rotational) of a car panel.
• The axis of a car panel hole and the axis of the pin should be same (in general)
• The pin tolerance for a geo pin will be of closer tolerance i.e. -0.15mm & for respot pin is -0.28mm.
• 1.Pin should engage 3-5 mm from the car part entry surface.
• 2.All pins should be accomodated with 2 ways adjustable shims irrespective of direction of arresting.
• 3.Round pin should be used in case of 4 wats arresting of car part if the hole is round.
• 4.Round pin should be used in case of 2 way arresting of car part if the holes is slot.
• 5.Diamond pins can be used for 4 ways arresting of car parts only if the hole is round
• 6.Diamond pins can be used for 2 way arresting of car part only if the hole is slot.

• PIN

  Pin is the part which locates the car panel. It can be a make part or standard part.

  Pin should grinding surface on shaft with fits on to which the pin retainer will be fitted.

  The mounting surface of the pin should be fie=ne machined surface.

  The pin should have a step machine surface to lock the ratation,which matches with the pin retainer.

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

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

  A pin must be hardened (Heat tratment) and black oxide finished in general.

• PIN DESIGN 1

PIN DESIGN 2

PIN RETAINER

A Pin retainer is a part which hold the pin in position, the pin retainer can either be a make part or a standard part.

Pin reayiner should have a hole with a fit, on to which the pin will be fixed.

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

The pin 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 two dowel holes (pins) and least wit one screw hole to maintain the tolerance.

PIN RETAINER DESIGN 1

PIN RETAINER DESIGN 2

BLOCK/ L-BLOCK

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

DESIGN 1

DESIGN 2

SHIMS

Shims and spacer are some standard parts in general,which ae used for adjustments of locators (NC Blocks and Pin retainer) for 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 on a unit to a riser.In general the blade can be either a make part or a standard part.

RISER

It is a part on which all the parts of a unit are mounted and is mounted on the base plate of a tool.

TYPE1...

TYPE 2 :

DOWEL HOLES & MACHINED SURFACE

All make parts which are to be assembled should be designed with two dowel holes and at least 1 to 6 threaded/free hole (depends on size) 7 to be fine machined for the mounting surface with 3 to 5mm step machining.

DESIGN METHODOLOGY

1. The project is to be titled with all the parts in the feature tree of the CATIA must follow the same process for easy identification of parts in the assembly.
2. The centre of the hole is taken and the pin outline is moulded as per the standard.
3. If there are any standard parts, it is advisible to use the standard parts as many as possible.
4. Retainer are mainly used to accomodate the shimming directions as per fundamental in general. Also in some cases used for other design feasibility
5. The block are modelled in such a manner that the pin can be adjusted in logitudinal and translational direction.
6. A 5mm space is provided betwwen the block and retainers as the shims or spacer blocks are present.
7. The dowel holes are present in all the parts of the pin unit which are to be assembled with tolerance should be designed with 2 dowels and at least of 1 to 6 threaded /free holes and to be fine machined for the mounting surface with 3 to 5mm step machining

Design 1.

DESIGN 2.

OVER ALL VIEW 2 TYPES OF DESIGN

2. Design 2 Different types of Retractable Pin Unit with Different Pins, Riser, Blade, Cylinder, and Block.

RETRACTABLE PIN 1

2.RETRACTABLE PIN 2 :

RETRACTABLE PIN 1 & 2 ASSEMBLY TOGETHER