Week 11 - Project - A pillar Design with Master Section

AIM

Create the A Pillar Plastic component through the given Class-A surface and master section and perform Draft analysis.

A PILLAR:

The A-pillars on each side of the windshield come up to be joined together by the header rail across the top of the windshield.

A-Pillars straddle the windshield, B-Pillars are in the middle of the passenger compartment (just behind the front doors) and C-Pillars are those at the rear of the passenger compartment.

TOOLING AXIS:

Tooling axis is the direction in which the core and cavity opens. If we are using proper tooling axis, we can avoid adding side cores thus the cost of manufacturing the component can be reduced.

It is defined as the direction in which the mould/core and cavity open. Selection of the direction of the tooling axis depends on the ease at which components can be easily ejected.

Generally tooling axis is decided from the natural axis of the design, that is, tooling axis is analysed with the x, y and z axis of the system. If the axis doesn’t clear the draft analysis, the next step is to look for the surface in which the drafting axis can be created in such a way that the axis is normal to the surface taken. These are the methods of deciding tooling axis. Bisecting method is the least used method.

Draft analysis in Catia:

Step 1: Ensure that customize view parameter is enabled and material mode is opted in view mode customization.

Step 2: Now go to insert > analysis > feature draft analysis.

Step 3: Drag axis bar to the tooling direction of part.

Step 4: Check for draft.

Surface will be in green if the draft angle is more than 3 degrees, blue if draft angle is between 0 to 3 degree and red if draft angle is less than zero degree.

Three degree is the nominal value for draft, whereas 0.5 degree can also be manufactured at ribs.

DOG HOUSE:

It is an engineering feature used in plastic trim design. It is used as a supporting feature. By using dog house, we can support the other engineering features like heat stakes, screw boss and locators to locate them at a certain height where we cannot violate the design rules for the features. By using doghouse, we can avoid sink marks in class A surface.

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

PROCEDURE

Class A Surface

• Class A surface is obtained as the input.
• Join all the surfaces to obtain Class A surface if different surfaces are given as input and ensure no gap is present between any surfaces. Thus, Class A surface is obtained and publish it. Here, the provided surface is completely joined and can be taken as class A surface.
• Publish class A surface.

Creation Of Class B Surface

• Now, Class B surface has to be created. For this surface should be offsetted for 2.5mm.
• Publish class B surface.

From the master section, it is clear that the thickness to be provided for the plastic component is 2.5mm.

So, class B is offsetted for 2.5mm.

Creation Of Class C Surface

• Now class C surface has to be created and it is created from the boundaries obtained from the Class A surface. This boundary is provided as the input curve for sweep command. Using sweep command, class C surface is created.
• Appropriate sweep is the provided considering the flash and considering manufacturing procedures. Surfaces are extrapolated if necessary.
• Publish class C surface.

CLOSED SURFACE

Draft Analysis Of Plastic Component

Creation Of Doghouse

• Doghouse are created by following the design rules.
• For this, sketch is created from the master section provided.
• It is then made to closed body and is made to part model.
• Shell operation is performed to get hollow structure and then coring is done in order to avoid sink marks in the class A surface.
• Drafts are given for the surfaces as per design rules and proper fillets are also provided.
• As per the given master section, ribs and supporting features are also added in the doghouse.
• Then, the doghouse is added to the main body.

All the sketches used are iso-constraint.

Draft Analysis Of Plastic Component

• The obtained part is draft analysed to check for the correctness of obtained model by following the draft analysis procedure mentioned above.

Side core has to be created for the doghouse to get ejected. So, a side core axis is also created for checking the draft analysis of the component.

Minimum of 0.5-degree draft is provided and the B side engineering features are analysed using the side core axis. Green colour is obtained in the draft analysis, which indicates that the draft provided all are in correct direction.

Minimum of 1.5-degree draft is provided and the B side engineering features are analysed. Green colour is obtained in the draft analysis, which indicates that the draft provided all are in correct direction.

Picture of the Detailed tree structure: