Week 4:- Pin Unit Design Challenge

AIM: To design 2 different type of fixed pin unit with different pins, riser, blade and block and 2 different type of retractable pin units with different pins, riser, blade, cylinder and block.

Introduction:

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

Type of Pin unit:

Fixed pin unit: In this type of unit, the pin is fixed by means of a pin retainer and riser

Retractable pin unit: In this type of unit, there is the provision of moving of pin in the Up- down direction.

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.

In line Retractable Pin unit consist one Pin cylinder which operates the pin in one direction. In this unit Pin is directly mounted on the cylinder and it is must to have pin and cylinder in line with the hole or slot of the panel. Pin cylinder is controlled in two directions with the help of shimming. Below picture is an example of inline retractable pin cylinder.

Pin cylinders have various stroke sizes like 30mm,40mm,60mm. Cylinder. Uses of cylinder depends upon the area and available while building the fixture.

Purpose of PIN Unit:

• As by the 3-2-1 locating principle, the introduction of two pins helps to arrest the 6 degrees of freedom (4 axial and 2 radial movement) whereas the other 6 degree of freedom are arrested by introducing a minimum of three supports.
• Typically, the locating pins are used to locate a body part in a position sufficiently accurate to execute a welding process
• The body part is constrained by a set of appropriately locating pin so total constraint by locating pin should be fully constrained at all times to prevent any movement.

Fundamental of PIN Unit:

It is necessary to have two pins to locate a car panel. One pin must arrest 4 ways (4 translation) and the other must arrest 2 ways (2 rotational) of a car panel.

1. Pin should engage 3-5 mm from car part entry surface.
2. All pins should be accommodated with 2 ways adjustable shims irrespective of direction of arresting.
3. Round pin should be used in case of 4 way 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 hole is round.
5. Diamond pins can be used for 4 way arresting of car part only if the hole is round.
6. Diamond pins can be used for 2 ways arresting of car part only if the hole is slot.
7. The axis of the car panel hole and the axis of the pin should be the same in .

Requirement:

• Pin-Pin is the part that locate the car panel. It can be a male part of standard part.
• The Pin Should be grinding surface on a shaft with fits on to which the pin retainer
• The mounting surface of the pin should be a finely machined surface.
• The pin should have a step machine surface to lock the rotation, which matches with pin retainer
• All machined planes should be perpendicular to the axis of the pin Shaft.
• Pin must have a provision like a tapped hole from the bottom or a V-groove from the side.
• A pin must be hardened (Heat treatment) & Black oxide finished in general.

Typically, locating pins are used for controlled, fine tolerance positioning of a, for example a pallet that is moved along one axis, where the drive mechanism is not accurate and stable enough to place it in a position sufficient accurate to execute a particular process, the use of locating pins may be the best solution.

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 Spancers are some Standard parts in general, which are used for adjustments of locators (NC Blocks and Pin retainers) for desired value for the precise working of a unit with respect to car part. In general, to adjust the design to manufacturing deviation.

Design Methodology:

• The Desiging process is started by giving a project tiltle and proper structuriung of the specification tree.
• The Car Panel for which the fixture to be designed is imported into the project
• The assembly project below refer.

• The Hole and slot are located and the pins are designed as per the diameter of the hole and it is made sure that the axis of the pin and the axis of the hole must be coincident. The pins designed may be Round or Diamond Shape.

• Pin retainer are designed to accommodate the pin and also the shim.

• The Block are used to provided shimming in multiple directions. They are designed in such a way that shims are mounted for two-way adjustment.

• 5mm Shims are designed for the adjustment of the pin in multiple direction.

• The risers are designed such that all the above parts are mounted on it.The risers are mounted to the base of the fixture.

• The Parts that are to be assembled are provided with dowel holes and a threaded hole.Below are the image of different pin units.

• Assembly Image below attach with different view.

• Tree Structure

Conclusion:

As per the objective the 2 different types of fixed Pin unit (P00_Z01_ST10_00_00_Pin_unit) and (P00_Z01_ST10_00_01_Pin_unit) with different pin, pin retainer, Blade and riser and 2 different types of retractable pin unit ,with different pins ,pin retainer ,blade ,riser and cylinder are designed and rendered using CATIA V5 Successfully.