Week 9 - Attachment Feature Creation - Challenge 2

Aim: To create the tooling axis for the given Class-A surface of the Coin Holder and create a solid part along with Class-B and Class-C surface. Also create Ribs, Screw Boss and Dog House with reference to the design rules.

Procedure: The input model for the draft analysis is the class-A surface given by the class-A designers as shown below:

Fig. 1: Class-A Surface of the Coin Holder

Considering the shape of the given component, the tooling axis is made in the Z direction at the center of the base.

Put a point at the center of the base of the Class-A surface, and draw a line through the point in the Z-direction. Name this line as the Tooling Axis.

This tooling axis and the Coin Holder surface need to be accessed multiple times and hence, need to be published. Go to Tools>Publication. These will be published in the feature tree.

Next step is to perform the draft analysis of the part with reference to the Tooling Axis. Go to Insert>Analysis>Feature Draft Analysis. Make sure that the View Mode Customization is set to the Material Mode as shown below:

Fig. 2: View Mode Customization

The draft analysis of the Class-A surface w.r.t. the tooling axis is shown below:

Fig. 3: Draft Analysis of the Class-A Surface

The green coloured faces are given a draft of certain amount and can be cleared using the tooling axis. The faces coloured in blue colour do not have a draft w.r.t. the tooling axis and hence, these surfaces cannot be cleared using the tooling axis.

Also, we are not allowed to change the shape of the given Class-A surface, hence we will proceed building the Class-B and Class-C surface on this part only.

When the Screw Boss and Dog House are added into the part, a side core is required to clear those B-Surface features. Draw a line parallel to the Z axis and name it as Side Core Tooling Axis. The draft on the faces of the Dog House are given along this side core axis.

For the closed surface, the faces which do not get cleared w.r.t. the main tooling axis, we need to use the side core tooling axis as shown.

A similar approach was followed to perform the draft analysis of the closed surface, and the results are shown below:

Fig. 4.1: Draft Analysis of the Solid part with Rib, Screw Boss and Dog House w.r.t Main Tooling Axis

Fig. 4.2: Draft Analysis of the Solid part with Rib, Screw Boss and Dog House w.r.t Side Core Axis

Creating the Class-B Surface:

The Class-B surface was divided into multiple parts, the base, the side wall, the top wall, and the flanges. The surfaces were extracted individually and, commands such as Untrim, Offset and Extrapolate were used to make these surfaces. These surfaces were then trimmed together to get the final Class-B surface. Finally, the edge fillets were applied in the appropriate positions. The final Class-B surface is shown below:

Fig. 5: Class-B Surface

Creating the Class-C surface:

To create the Class-C surface, use boundary command on the Class-A surface and use the Sweep command to make a surface perpendicular to the outer faces of the Class-A surface. The Class-C surface is shown below:

Fig. 6: Class-C Surface

These surfaces are trimmed together and a closed body is created in the Part Design Workbench to make a solid part. The ribs can be made on this solid by following the given steps:

1. Create a Geometrical set named Rib Design and extract the base surface. On this surface draw a line as shown below and make it as output feature.
2. Extrude this line in the Tooling Axis direction for 2.5 times the thickness of the part i.e. 12.5mm in this case.
3. In the Part Design Workbench, use Thick Surface command to give the thickness of the rib equal to 0.4 times thickness of the part i.e. 1mm in this case.
4. Use Draft command to give a draft of 0.5 degree to the faces of the rib.
5. Assemble this body with the solid body.
6. Fillet the edges of the rib with fillet radius = 0.25mm
7. In the sketch drawn earlier for the rib, offset the line by 6mm and again follow the steps to make another rib.
8. In the Design Rib geometrical set, ‘Intersect’ the Coin Holder body and a plane parallel to the XY plane and passing through the projection point.
9. Create a Tri-tangent circle at the Rib base and measure the diameter to complete the Rib Root Thickness Analysis as shown below.

Fig. 7: Rib Design Sketch

Fig. 8: Rib root thickness analysis

Creating the Screw Boss:

1. Create a Geometrical set named Screw Boss and make a sketch of circles as shown below. ‘Pad’ these up-to 12mm.
2. Draft the faces of the Screw Boss by 0.5 degree and give fillets of minimum radius of 0.5mm
3. Next, create a line sketch as shown and extrude the surface up-to 10mm. Thicken these surfaces to have Rib thickness of 1mm. Follow the above mentioned rules for rib design and give appropriate fillets and drafts.
4. ‘Union Trim’ the ribs and the circular feature in a separate body.
5. ‘Assemble’ this Screw Boss Body with the main body. Copy the screw boss and ‘Paste Special’ in another body and translate this to the diagonally opposite corner on the Class-B Surface.

Fig. 9: Sketch to draw the screw boss

Fig. 10: Sketch to make Screw Boss Ribs

Creating the Dog House:

The second screw boss needs to be placed on a Dog House. Follow the steps to make a Dog House feature w.r.t. the design rules.

1. Extract the base surface from the Class-A surface, offset it by 2.5mm and draw a positioned sketch on this offset surface for the profile of the Dog House as shown.
2. ‘Sweep’ this surface with a draft angle of 1.5 degree. Close the top surface of the profile by offsetting the base surface and trimming these together.
3. Insert a new body, and use ‘Thick Surface’ to thicken this profile by 2mm on the outside. Give a draft of 0.5 degree to the outer surface and fillet it accordingly.
4. The thick surface will form an improper profile. Extract the inner surface and offset it and trim it to get a smooth profile of the dog house.
5. Extract the inner surface of the Dog House and offset it by 1mm towards the outside. Offset the base surface by 4mm and split the solid body with this surface to get the base section of the Dog House.
6. Give appropriate drafts of 0.5 degree to 1.5 degree and fillet the edges to complete the Dog House.
7. ‘Assemble’ this body with the main body before the placement of the translated screw boss in the feature tree.
8. Translate this screw boss by 21.5mm in the Z direction to place it on the top surface of the Dog House.

Fig. 11: Sketch for Dog House profile

The orientation of the Coin Holder is shown below:

Fig. 12: Front View

Fig. 13: Top View

Fig. 14: Right View

Fig. 15: Isometric View

The feature tree of the Coin Holder is shown below:

Conclusion: The draft analysis of the given Class-A surface was completed successfully and a closed surface was built out of the given Class-A surface. Also ribs, screw boss and dog house were created with reference to the design rules.