Desiging Pin Units Design for a given Spare Wheel Well

Desiging of Pin Units Using CATIA V5

AIM:-

•  To design the fixed pin unit and the retracting pin unit for locating a biw panel in a fixture.

INTRODUCTION:

1. FIXED PIN UNIT: Fixed Pin unit is a unit designed to locate the car panel using pins. And below are the different parts of a fixed pin unit in general.
2. 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. And below are the differengparts of a retractable pin unit in general.

The basic part of the Pin Unit are

• Pin (Round, Diamond Shape)
• Pin Retainer (To hold the Pin in particular postion)
• Block
• Shims
• Blade
• Riser

Pin: Pin a part which locates the car panel. A pin can either be a make part or a standard part also.

• Pin should have grinding surface on shaft with fits on to which the pin retainer will be fitted.
• The mounting surface of the pin should be a fine machined surface.
• The pin should have a step machine surface to lock the rotation, which matches with the pin retainer
• The mounting surface of the pin retainer to the blocks should be a machined surface.
• All machined planes should be perpendicular to the axis of the pin shaft.
• Pin must have a fastening provision like tapped hole from the bottom or a V grove from the side.
• A pin must be hardened (Heat treatment) and black oxide finished in general.

Pin must be hardened up to 55-60 HRC.

Harden materials like C45, 16MNCR5, 20MNCR5, M31 are general used for pin

• Round Pin is used to arrest 4 DOF

Image of the Round Pin of the Fixed Pin Unit 1

• Diamond Pin is used to arrest only 2 DOF. (This is basically used for slot type holes in BIW)

Image of the Diamond Pin of the Fixed Pin Unit 2

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.

• 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.

Image of the Pin Retainer of the Fixed Pin Unit 1

Block or L Block: These parts are mainly used to ammmodate the shimming directions as per fundamental in general. Also in some cases used for other design feasibility.

Image of the Block of the Fixed Pin Unit 1

Shims or 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.

Image of the Shim_Pack of the Fixed Pin Unit 1

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.

Image of the Blade of the Fixed Pin Unit 1

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..

Image of the Riser of the Fixed Pin Unit 1

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 I to 6 threaded / free hole(depends on size), And to be fine machined for the mounting surface with 3 to 5 mm step machining. Helps for Reducing Setup Time and Repeatable Positioning of the parts. Dowel holes are indispensable in BIW fixture design, playing a vital role in achieving precision, repeatability, and overall excellence in modern automotive manufacturing.

Image of the Dowel Hole on Block of the Fixed Pin Unit 1

Guidelines that must be taken into account when developing the PIN unit

• It is necessary to have two pins to locate a car panel. And here one pin must arrest 4 way(4 translational) and other must arrest 2 way (i.e. 2 rotational) of a car panel.
• Pin should engage 3 to 5 mm from car part entry surface.
• All pins should be accomodated with 2 way adjustable shims irrespective of direction of arresting.
• Round pins should be used in case of 4 way arresting of car part if the hole iS round.
• Round pins can be used for 2 way arresting of car part only if the hole is slot.
• Diamond pins should be used in case of 2 way arresting of car part if the hole is round.
• Diamond pins should be used in case of 4 way arresting of car part if the hole is slotted.
  
  
  
  Image of Round Pin and Diamond Pin

• The axis of the car panel hole and the axis of the pin should be same.(ln general)

The pin tolerance for a geo pin will be of closer tolerance i.e. -O. 15mm and for re-spot pin is -0.28mm

Design Methodology:

1.The designing process is started by giving a project title and proper structuring of the specification tree.

Image of the arranging the parts in the Project

Image of the arranging the parts in the project in a specfic manner.

Image of feature tree of the Project

Image of the Project with feature tree

Image of Fixed Pin Unit 1

Image of Fixed Pin Unit 2

Image of Retractable Pin Unit 1 with Round Pin

Image of Retractable Pin Unit 2 with Diamond Pin

Image of the Project B

Image fo the all Pin Units

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NOTE: All the files have been uploaded as a Single ZIP file and attached.