Week 9 - Project - A pillar Design with Master Section

DESIGNING A PILLAR USING MASTER SECTION

OBJECTIVES

• To create B side features for the A surface using the master section given to us as an input.
• To create main and side core tooling axis for A pillar and its B side features.
• To do the draft analysis of the overall model of the A pillar i.e including B side features.

INTRODUCTION

MASTER SECTION: Master sections development takes place during feasibility check and concept validation stages of the product life cycle. These are typically the guides for design requirements and which decides the component packaging after the development of the concept design, i.e class A surfaces.

Master section helps us to decide the feasibility of the concept design, the clearances, the packaging and the fixation strategy of a component before converting the concept design into a solid 3D engineering design.

During the period of vehicle concept design the evaluation of the master section performance depends mainly on the reference vehicle data and experience of structure design engineer.

DESIGNING METHODOLOGY:

CREATION OF MAIN AND SIDE CORE TOOLING AXIS

Apart from A surface and C surfaces we also need to consider the B side attachment features in order to create the tooling axis because all the attachment features have a large number of surfaces parallel to the tooling direction.

For creating the tooling we can take reference from the master sections of the B side features and create tooling axis accordingly.

For the creation of tooling axis we use the bisecting methord in which the lines which seems to create problems in the moulding are noted

and duplicate extended line is created out of it. Of which a bisecting line is again created and further we check the feasibility of the tooling direction by draft analysis

extracted lines are marcked in the picture

draft analysis of class A showing that the chosen axis is correct

The side core axis is created after creating the surfaces of the b side features

CLASS B SURFACE CREATION

We need a thickness of 2.5mm for the part(as observed from master section) so in order to create the class B surface we'll give an offset value of 2.5 mm to class A surface.

After applying the offset command we'll see some of the patches of the resulting surface are not generating so we have to recreate those patches by using multi-section surface command.

On joining the recreated patches with the offseted surface we'll get the class B surface

CLASS C SURFACE CREATION

Extract the side edges, front edges and rear edges of the class A surface and use sweep command using "with refrence to draft" option and make the draft angle equal to 3 degrees.

For the rest of the edges use multi-section surfaces command to make surfaces inline with the major surfaces created through sweep.

Join all the surfaces together using join command.

SOLID BODY CREATION

Join the class A surface with class C surface.

Trim the resulting surface with class C surface.

The resulting trim we get is the closed shell body of A pillar.

Finally use closed surface command in the part design workbench which would lead the shell body into a part body.

CREATION OF B SIDE FEATURES

DOGHOUSE: Dog house are basically used to avoid sink marks on the A surfaces, specially at those regions where other attachment features like screw boss is attached, placing such features like screw boss would add the thickness of the component at that particular region and this would leads to non uniform cooling of the molten platics during moulding resulting to shrinkage of the body from the outer side.

The creation of doghouse is done completely using the master sections, first we create lines by taking the refrences from the master section and then extruded it along the side core axis so that we would get the wall surfaces of the doghouse. Doing this for the 4 sides and trimming them would give us the shape of the dog house

Add material to the trimmed surface by using the thicken command in the part design workbench. Make sure we give thickness according to the doghouse master section.

We can further use split command to split the extra or unwanted material portion and give proper shape to the doghouse according to the master section. We also need to use the split command to reduce the thickness of the doghouse from the bottom i.e 3mm to 6mm upward from the bottom edge touching the B surface.

The thickness to be reduced should be not less than 40% of the wall thickness.

Each faces of the doghouse is drafted to a value of 3 degrees and for some faces the drafting angle was redused to upto 0.3 by considering the thickness of the part. A minimum fillet value of 0.25mm is also required to all the edges.

For the creation of the cut out in the top surface of the doghouse a sketch of it is made and created a pad, which is then removed out of the doghouse using boolean operation

for the ctreation of the ribs inside the dog house a similar methord was choosen by extracting extruding and thickening the desired lines

Finally we will use the union trim boolean operation to join both the doghouses to the main body and trimming off the unwanted material at the same time.

The draft analysis of the b side features an the completed body shows feasible draft angle