Week 10 - Challenge 2- Attachment Feature Creation (Dog House)

AIM

         To create a Door Trim Plastic Component through a given Class A Surface, create the Dog house (attachment feature) and perform Draft Analysis on the final plastic component.

OBJECTIVE

• To make sure that the model meets the requirements of the draft angle.
• To create the Tooling axis using bisecting method / suitable axis.
• To perform Draft analysis on the given Class A Surface.
• To create the required Class B and Class C surfaces.
• To obtain a solid body from the surface using Close Surface feature.
• To create the Dog house as design rules.
• To perform draft analysis on final plastic component.

CLASS A SURFACE

• Class ‘A’ surfaces are primarily used in the automotive environment and refer to those surfaces which are visible in a product. In other words: A - class surfaces are those aesthetic/free-form surfaces, which are visible to us (interior/exterior), and have an optimal aesthetic shape and high surface quality.
• The surfaces or regions which are visible nowadays are considered for Class-A modelling. It is one of the reasons why the importance of Class-A modelling is increasing day by day. Majority of the time this term is used in Plastic Part designs. 

CLASS B SURFACE

• The Class B surface is created from the Class A surface, keeping the thickness of the component in check.
• The Class B surface resembles an offsetted surface from the Class A.

 

CLASS C SURFACE

• The Class C surface is used to bind the Class A and Class B surface together in order to form a closed surface.

PROCEDURE

Creating Tool Axis

• Initially the given Class-A surface was imported and checked for any discrepancies in the boundary and performed draft analysis on it at 3-degree draft.
• The ejection from the mould after manufacturing the interior trim must have the nominal 3-degree draft angle.
• The Y direction is suitable for creating the tooling axis because in the Y direction most of the surfaces are clearing while performing draft analysis.
• The base surface of the class-A was extracted to create a reference point on the surface using the point, create a line in the Y-direction.

• Generally tooling axis is created using bisecting line method but here A line normal to the surface is created in the y direction and considered the tooling axis.

Creating Class B surface

• First offsetting entire class A surface to 3mm in the inward direction as 3mm is thickness of component.
• Some of errors were created in the offsetted surface like incomplete surfaces, gaps, small patches.

• These errors were solved by extracting surfaces, join by sub-elements to remove, extrapolating, sweep, multi-section surfaces etc commands.
• Joining patched surface to main surface, Class B surface was created.

Creating Class C surface

• We first extract the edges from the Class A surface with the help of the multi extract command which we create the path for a sweep for class C.
• Create a sweep with reference to the curve and the reference surface with a 90-degree angle and give the inside direction Check for the continuity of the surfaces if there is any gap go for extrapolated and trim all together now, we will get the class C surface.

• Joining class-A surface and class-C surfaces together.

 

Creating Solid Body

• Later, Joined Class A & Class C surface is trimmed with Class B surface to form the Door trim surface.

• Using the surface created, the solid plastic component was obtained using the Close surface feature present in the part workbench.

• The Tooling axis, Class A, B and C surfaces were published.

Attachment Feature Creation DOG HOUSE DESIGN

Dog house is an engineering feature used in the plastic trim design. Dog houses are used as supporting features. Sometimes other engineering features like snaps; locators, etc. are mounded on them to increase their Height. Dog house and other engineering Features are built on B-surface.

Design rules for Dog house creation:

• "C" is where the doghouse contacts the backside of the 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

Dog house design procedure by considering the design rules:

• Extracting the surface on which we want to create the dog house and create a sketch on a plane.
• Using the sweep command, creating surface of dog house and closing top open by extrude and trimming.
• With help of thick surface command, create part body of dog house about 2mm.
• Side core axis is created in the x direction on the same point as the main tooling direction created.
• Drafting inside walls along side core axis and filleting inner and outer edges.
• The height of (B) should be between 3.0 – 6.0 mm by considering the design rule here we offset the class b surface to 4mm.
• Doghouse wall thickness at the intersection of the part wall (C) should be 40% or less than the main wall stock (T). we offset the 1mm from the side wall by considering the design rule.
• Now we trimmed the surfaces and split the surface with the part body.
• Now apply the draft on the inside edge where the bottom cut is done and filleting those edges.
• Finally, the dog house is created by considering the design rules and performed draft analysis and by same procedure, created another dog house at required position.

DRAFT ANALYSIS

• First, we should change model into material mode.
• Go to insert and in analysis select feature draft analysis.
• Align the compass along tooling axis and lock it.
• Next click on the surface and see that the surface is within the permissible limit of the values.
• The green colour area shows that it satisfies the 3-degree draft angle. If not satisfied then by using the Running point tool the area is measured and then altered to get a successful draft for the created tooling direction.

On given Class A surface

 

On obtained PART BODY

CONCLUSION

• The creation of Tooling axis and Draft analysis were performed.
• The solid component was created from the surface geometry.
• Attachment Feature like Dog houses were created as per design rules.
• The necessary screenshots and files were attached.
• The Class A, B, & C surfaces and also the Tooling Direction have been Published.