Week 4:- Pin Unit Design Challenge
Aim:- Design of 2 Fixed Pin Units with different risers, blades, etc. And Design of 2 Retractable Pin Units
with different risers, blades, etc.
Introduction:- there are two types of pin units one is a type pin unit and another one is a retractable type pin unit.
in detail mentioned below.
Fix pin unit -
An assembly of standard and manufacturing parts consisting location pin is called a Pin unit. A pin unit in which the pin’s position
is fixed is called a Fixed Pin Unit. The pin unit is used to lock the rotational position of the panel. Round Pin is used to control the panel in
two directions while Diamond Pin is used to control the panel in one direction.
Retractable Pin Unit
An inline Retractable Pin unit consists of one Pin cylinder that operates the pin in one direction. In this unit Pin is directly mounted
on the cylinder and it is a must to have the pin and cylinder in line with the hole or slot of the panel. The pin cylinder is controlled in
two directions with the help of shimming. The below picture is an example of an inline retractable pin cylinder.
Type of Pin unit:
Fixed pin unit: In this type of unit, the pin is fixed using 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, the Retractable Pin unit consists of one Pin cylinder which operates the pin in one direction. In this unit Pin is directly mounted on the cylinder and it is a must to have the pin and cylinder in line with the hole or slot of the panel. The pin cylinder is controlled in two directions with the help of shimming. The below picture is an example of an inline retractable pin cylinder.
Pin cylinders have various stroke sizes like 30mm,40mm, and 60mm. Cylinder. Uses of cylinders depend upon the area and availability while building the fixture.
Purpose of PIN Unit:
As by the 3-2-1 locating principle, introducing two pins helps to arrest the 6 degrees of freedom (4 axial and 2 radial movement) whereas the other 6 degrees 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 pins so total constraint by locating pins 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.
The pin should engage 3-5 mm from the car part entry surface.
All pins should be accommodated with 2 ways adjustable shims irrespective of the direction of arresting.
The round pin should be used in case of 4-way arresting of the car part if the hole is round.
The round pin should be used in case of 2 way arresting the car part if the hole is round.
Diamond pins can be used for 4-way arresting of car parts only if the hole is round.
Diamond pins can be used in 2 ways to arrest the car parts only if the hole is slot.
The axis of the car panel hole and the axis of the pin should be the same.
Requirement:
Pin-Pin is the part that locates the car panel. It can be a male part or a standard part.
The Pin Should be grinding surface on a shaft with fits onto which the pin retainer
The mounting surface of the pin should be finely machined.
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.
The 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, 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 sufficiently accurately 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 fundamentals in general, also in some cases used for other design feasibility.
Shims/Spacers:
Shims and Spencers 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 concerning car parts. In general, to adjust the design to manufacturing deviation.
