Week 9 - Attachment Feature Creation - Challenge 2

AIM: - To create the Screw boss and Dog House for the center console coin holder by considering the design rules.

INTRODUCTION: -

SCREW BOSS: -

The screw boss is an attachment feature, it helps in locating and fastening the components together at mating location.

DOG HOUSE: -

Dog house in also a kind of attachment future used in plastic components. It is used where the screw boss requires additional height. We cannot directly impart more height to screw boss, this might lead to sink waves in component. It also used for mounting fasteners.

PROCEDURE: -

The screw boss and the dog house are created on the surface below the given component, a center console coin holder class-B. screw boss and the dog house are created for the purpose of screw accommodation and support keeping the plastic design rules.

Boss features are commonly found in injection molding designs. They are used to aid in the assembly of molded parts by providing a channel for a screw. Designing plastic screw bosses is fairly straightforward but there are few considerations to ensure a strong connection between parts and mitigate cosmetic defects.

The below surface of the component is extracted from the class-A surface. Insert a geometrical set and a positioned sketch is created with a projection point.

Constraint the circle with the axis created on the sketch and make sure the sketch is iso constrained. If there are any lines that are opened make them as construction lines.

Insert a part body for the screw boss and define it as the screw boss. By switching to part body design and pad the sketch as per the dimensions. Extend the other limit to a bit 1mm such that it intersects with the other surface.

Next, the solid created on the extracted surface should be drafted to 0.5degrees with the base as a neutral element in an upward direction.

Create a positioned sketch with the same projection point and draw the lines for ribs with the help of the previous sketch draw in the screw geometrical set. Make sure that the sketch is equidistant from the point and iso-constrained.

Insert a part body and rename it as ribs and pad the sketch to certain height and thickness of 1mm with a neutral element by giving the height of ribs as 10mm. draft the ribs to 0.5 degrees with the base as a neutral element. Select all the faces of the ribs.

Since the ribs are intersecting with the screw boss. Untrim the ribs with the screw boss and select the unwanted faces to remove.

Add the edge-fillet to the ribs and screw parts selecting all the surface as 0.25mm fillet radius.

Create a plane parallel to the point created in XY-direction and intersect the plane with the screw boss untrim and measure the distances.

Assemble the screw boss to the main part body and create another similar part design in another location. Copy and paste the screw boss part body and paste special with the main component. Now translate the screw boss in the required direction through the co-ordination system.

Now assemble the previously created screw boss solid to the main part body using Boolean operation.

Now create a dog house for the screw boss. Insert another geometrical set for the dog house creation and define it. Extract a surface from the class-A surface and offset it to 2.5mm. create a positioned sketch with point projection and draw the lines such that they are distant from the screw boss. Make sure that they are iso-constrained.

Now insert a part body for dog house and sweep it to a height more than the screw boss to 21mm.

Now off-set the main surface to the height 1mm less than the extruded surface and trim it.

Now define the part body and thicken the dog – house surface using the thick surface option to 2mm. remove the unwanted material by extracting and offsetting to 23mm and apply the split operation. Draft the thickened surface to 0.5degrees in the tooling direction.

Now give the edge fillet to the dog house in the radius as 1mm and outer radius as 3mm because of 2mm of 2mm thickness.

Now extract the main surface to 4mm upwards and similarly. Extract the inner wall surface of the thickened dog house to 0.8mm by the thickened dog house surface. The draft to the inner walls of the dog house is taken as 0.5 degrees.

Now draft the inner surface of the dog house to 0.5 degrees. Selecting the neutral surface and newly created tooling direction through the point on the surface of the wall.

Now extrude the top base of the dog house and offset it to 0.5mm and create a point over it.

Here, the screw boss which is copied from the main body is translated by the translate command. The screw-boss is translated by point to point.

Now assemble the part body of screw boss to the part body of the dog house and similarly assemble the dog house creation part body to the main part body through the Boolean operation.

Now perform the draft analysis of the features created. Unhide the main tooling axis and insert feature draft analysis place the compass on the main tooling axis and select on the whole component. Rename the analysis accordingly.

Since the dog house is having a projection perpendicular to the main tooling axis. The sliding drafting is also considered. Hence unhide the side tooling axis and perform the draft analysis in the sliding direction.

Insert the different geometrical sets and part bodies to easily differentiate them and draft all the required surface with the recommended draft angle. Fillets are added after all the operations and also publish the created surfaces and features to easily visualize them in the tree structure.