Week 9 - Project - Master Section Development

Aim

• To create B-pillar of an automotive by developing the given master section.
• To create tooling and lifter axis
• To perform draft analysis on the part
• To Design for manufacture guidelines

B-Pillar

The roof support pillar located in the car's midsection, between the A and C pillars. The pillars are named alphabetically by order of placement from front to back of the car, in profile view.The function of B pillar in cars is to serve as frame for door,roof fitting and to provide side impact protection.The pillar post trim is a decorative piece you can mount on the vertical door and window pillars of your automobile.

Input- Class A surface with Master section

The class A surface is the outer skin or the styling surface of the part. The master section has all relevant information to create the plastic design features.

we can see that the class A surface has no flange so we must create the flange with help of the master section.

Draft

Draft is the amount of taper for molded or cast parts perpendicular to the parting line. It also a slant that is applied to each side of most features of an injection molded part By applying appropriate draft angle the mold will be easier to remove and it also accounts for thermoplastic shrinkage in Injection molding. The draft may also alter the form and fit of the part during assembly.

A draft of minimum of 0.5 degree draft per side is recommended. For textured sidewalls use an additional 0.4 degree draft per 0.1mm depth of texture. But maintaning the minimum draft could be costly during manufacturing hence an optimum draft angle of 3 degree could be maintained.

Design Methodology

Types of surfaces involved

Class A surface

This is the input surface for the design engineers for designing the inner panels or features of the parts. It is the styling surface of the component which shows the outer appearance of the parts.

Class B surface

The thickened surface is called as B surface. It is also called as engineering surface. This surface contains all the necessary part feature like fillet, ribs, bosses etc.

Class C surface

The surface joining the class A surface and class B surface is called as C surface.

Steps involved in creating Door Applique desgin

Tree structure

Check the class A surface

• The input (class A surface) is checked for any gaps or disjoints using the join or boundary commands.
• If there is any Minor error the it can be rectified or else send back to the Class A surface designer to make the necessary modifications properly.

In this case we can see that the Class A surface does not have any gaps or disjoints and has smooth and continuous boundary.

Create the Tooling axis

The tooling axis is the direction in which the core and cavity opens and closes.

For this component we can create the tooling axis by using the bescting line option between the points from the master section.

The plastic design features like dog house inner faces cannot be cleared with main tooling axis hence and lifter axis must be create to manufacture the part.

Class B Surface

Class A surface is offsetted by 2mm to create the class B surface.

Flange creation

The flange is created by sweep command in both Class A and B surface. The flange is made parallel to the master section provided.

Class C surface

The class C surface is created along the class A boundary with proper draft angle and then it is trimmed with Class B surface to get a closed volume.

Class A and C surface

Closed Surface after trim

Dog House With 4 way locator

Dog House guidelines

• Doghouse wall thickness at the intersection of the part wall ( C ) should be 40% or less than the main wall stock ( T ).
• Height of ( B ) should be between 3.0 – 6.0 mm
• Draft - 0.5 degrees on walls of boss
• Thickness - Typically 40%* of the nominal wall at the base.
• Radii - 0.25mm maximum radii.

The required iso-constrained sketches are created.

The sketches are extruded and extrapolated and trimmed as per required output

The surface is thickened and spillted to get the required output. The necessary draft, fillet and chamfer are applied. The four way locator is also created on the top of the dog house.

Rib

The sketch is extruded and thikened.The necessary draft, fillet is applied

Publish

In the next step publish the tooling axis and Class A,B,C surfaces so that we can access it easily and use it for further creation of surfaces or thick body.

Draft Analysis

Once the tooling axis is created the draft analysis can be done. For viewing the draft analysis results we need to change the view parameters into customise mode enabling only the material.

Go to insert-analysis-feature draft analysis.

The compass option is used to choose the tooling axis. The color coding shows the result of the draft analysis done. The limits of the draft angle can be changes according to the needs.

Types of the modes in the analysis

A single limt can be chosen to show the positive or negative draft

Multiple limits can also be set based on the requirements

The draft angle value can be found at any given point of the surface. For this case 0.5 egree is chosen as the optimum angle and we can see that the some parts of the model has positive draft angle highlighted in green color and some parts with zero draft highlighted in blue color. The negative draft is shown in red color.

Class A Surface Draft Analysis

We can see that few of the patches in Class A surface is not having the proper draft due to problem in class A surface. Hence it must be informed to class A designer and addressed.

Note The given class A can be cleared by making a complex angle of the tooling axis which would make the manufacturing the part more difficult and expensive. Hence the class A surface needs to be modified.

Class B Surface

Class A and C surface

Class C surface

Dog house and 4 way locator

Dog house Inner faces are cleared with lifter axis

Entire part with ribs

Part Images

Conclusion

Thus the B-pillar is developed from the given class A and Master section and the draft analysis was performed.