Week 9 - Attachment Feature Creation - Challenge 2

Aim :- The Objective Of this Report is to Create the Dog House for the Door Trim considering the design rules .

Introduction :-

• Dog house is an engineering feature used in plastic trim design. Dog houses are used as supporting feature. Sometimes other engineering features like snaps; locators etc. are mounded on them to increase their strength.
• Dog houses are subjected to draft analysis to prevent breakage of the component during ejection from mould cavity. Dog house and other engineering components are built on B-surface.

Procedure to Create the Model :-

• Creating the tooling axis
• Draft analysis of Class A surface
• Creating Class B surface
• Creating Class C surface
• Surface and solid body
• Draft analysis of Solid body
• Engineering feature Dog House
• Draft analysis of Solid body with engineering feature

DESIGN METHODOLOGY :-

• The Class-A Surface would be provided to us by the styling team of the OEM.
• Class-A surface means visible Styling surface. It gives the aesthetic of the component which is created by the styling team and gives to the part design engineer to create the part with all engineering aspects.

• The first step is to check the continuity of the class A surface. This is to ensure that there is no gap between surfaces.

• If we find any gap then we should fix that first.

• We can analysis the class A surface through visual inspection.

• To make sure that the given surface has no gap in between them. We can check it through the help of Join or boundary commands.

Procedure for creating the tooling axis :-

• Tooling axis represents the opening and closing of the mold core and cavity during the manufacturing of the components.

• A plastic product designer should consider the best tooling direction to cutdown the cost of the component very less.

Method opted for creating tooling axis for the Door Trim :-

• Check the best tooling direction for the given surface.
• We can find out the best tooling direction by cross checking all the three axes.
• Here we take the tooling Axis from Extracting the most Flat Surface.

• The method choose to create the tooling axis is first extracted a surface and create a midpoint on that surface.
• Then created a with the point and direction along the normal to the Surface.
• Hence going with the axis created will not make any difficulties during the draft analysis.

SURFACE-B CREATION :-

• Class-B surface means thickness of a part it is not visible and is inside part. In other words, Class-B surface is a surface below a certain thickness from the class-A surface.

• This is the surface that contains engineering aspects of a model

• Offset the class-A surface to 2.5mm inward direction.

• Rework on the patches and discontinuity of the offset surfaces using the features like extract, multi-extract, sweep, multi-section surfaces, extrapolate.
• To ensure the continuity of the Class-B surfaces check the boundary command to find out the boundary.Hence class-B surface creation is done.

Surface-C Creation :-

• The Surface that joins class-A and class-B surfaces is called as class-C surface.

• Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled

Since it is a complex class-A surface, we cannot simply create the class-A boundary curve and sweep it at one shot.

• Hence, we need to create smaller curves using boundary command and then create sweep of 93 degree or 87 degeree accroding to the direction with reference to the surface option.

Creating the final closed Surface:-

• First step is to join the CLASS-A surface with CLASS-C surface.
• Then Trim the Joined surface with CLASS-B surface to achieve the final Door Trim Lower surface.
• Switch to the part design work bench and using the close surface command to create the door trim lower solid part.

Creation of Engineering Feature Dog House:-

• Dog houses are designed to avoid SINK MARK created on the CLASS-A surface by screw bosses and to solve the length issues when giving screw bosses which need to be assembled to other components.
• It is also useful when perpendicular screw bosses are required on the part to the tooling direction.

Design Consideration to create the Dog House :-

• 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

• Minimum width of the dog house is 12 mm.
• Minimum draft for the do house is 1.5 degree to die draw.

Procedure to Create the Dog House :-

• First step is to create a side core axis.
• I have chosen normal to the point method for creating the side core tooling axis.

• Create the dog house by creating positioned sketch on the z-x plane. Using extrude or sweep method create dog hose outer walls.

• Now close the top wall using a Suface which is Normal to the Tooling Axis.
• Using thicken command in the part workbench, create a solid part of the dog house.
• Give proper draft angles and fillets by considering the design rules.

Then Using Boolean operation, union trim the dog house body part with the door trim component.

DRAFT ANALYSIS :-

• The Draft Analysis is a command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on colour ranges identifying zones on the analysed element where the deviation from the draft direction at any point, corresponds to specified values.
• Draft analysis is done after determining the tooling axis, draft analysis is used to check whether the minimum draft (3 degrees) is maintained or not.

• Procedure for performing the draft analysis are as follows
• Change the view mode of the component to be in customized parameter mode and then select the shading mode as materials.
• Then open the featured draft analysis tool from the insert menu.
• Then click on use the compass to define the current drafting direction and then drag and align the compass on the Tooling axis.
• Then lock the draft direction and perform draft analysis by clicking on the component.

Colour Range representation

GREEN colour - Positive Draft

RED colour – Zero draft

BLUE colour – Negative Draft

Draft analysis of DOG HOUSE using the Side Core Axis :-

Draft analysis of final Door trim component :-

Tree Structure Of the Door Trim Lower :-

Conclusion :-

Now successfully created the CLASS B and C surfaces using the given CLASS A surface of door trim and craeted main tooling axis and side core tooling axis. Performed draft analysis for both final component and the dog house.