Week 9 - Project - A pillar Design with Master Section

A pillar Design with Master Section

OBJECTIVES:

• To create the class B and class C surfaces from the given class A surface
• To form a solid geometry by combining all the surfaces
• To create a dog house for the solid part whilst following the design rules
• To perform draft analysis on the class A surface and the solid part model

A-PILLAR

The structure of an automobile body consists of various support structures like the roof, pillars, and floor. The car pillar in the vehicle stands in the near-vertical position, which supports the vehicle’s roof. The pillars found most commonly are the A, B, C and D pillars.

The A pillars are the first set of upright sections on a car body that links the lower body to the roof of the car. It acts as a major support structure during impacts and it is also a median to support the windshield of the vehicle. Apart from structural advantages the A pillar has a large effect on the overall aerodynamics of the vehicle.

MASTER SECTION:

Master sections are the guides for design requirements which decide the component packaging after the styling surface

PRE-DESIGN CHECKS:

Before starting the creation of the class B surface we must ensure that the given class A surface is properly closed and the surface continuity is proper. This can be done either with the help of the join operation or by using the boundary feature.

TOOLING AXIS:

• The next step is to create the tooling axis for the part which will determine the direction in which the core and cavity of the mould will move.
• Designer must ensure that all holes and slots are covered in the main tooling and thus side core must be avoided whenever possible
• After analysing visually for the best possible tooling axis, an reference tooling axis is created on the centre of one of the surfaces of the A pillar trim.
• The main tooling axis is created by using the bisecting method and by taking references from the master section

DRAFT ANALYSIS:

• Draft analysis is done on the class a surface after the tooling axis has been obtained
• The part must have a minimum draft angle of 3 degrees on all the tapered faces
• Using the feature draft analysis tool and the compass the part surface is validated for the minimum draft criteria

CLASS B SURFACE

• After all the validation has been done, the class B surface is created by offsetting the class B surface to a distance of 2.5 mm
• After offsetting a large opening in the surfaces is found which is closed with the help of sweep and multi section commands
• The class B surface is then extrapolated in parts to trim it along with the class C surface

CLASS C SURFACE

• The class C surface which connects the class A and class B surface is created by sweeping the boundary of the class A and using the class A as a reference.
• The sweep is divided into several parts in order to avoid complexity
• Surfaces which are parallel to the tooling direction are swept with the tooling axis as reference and with a draft angle of 3degrees

PART:

The final trim is created by joining the Class A and C surface and finally trimming it with the Class B surface. The combination of class A, B and C surface is then converted into a solid with the aid of close surface command in the part workbench

SIDE CORE AXIS:

The side core axis is created to normal to the plane formed along the master section. The dog house inner walls and all the ribs will be cleared using the side core axis

DESIGN OF DOG HOUSE:

• The two main purposes of a dog house are to avoid sink marks and to house various other engineering features like screw boss, locators etc.
• The dog house should follow certain design rules which are stated below

• Doghouse wall thickness at the intersection of the part wall (C) should be 40% or less than the main wall stock (T).
• The height of ( B ) should be between 3.0 – 6.0 mm

DRAFT ANALYSIS ON PART:

• Draft analysis is done on the final part with the tooling axis as reference
• Green surface indicates the areas where the draft is more than 0.5 degrees.
• Blue surface indicates the area having negative draft.