Week 10 - Challenge 1- Attachment Feature Creation (Ribs & Screw Boss)
Objective: The main objective of this challenge is to create the B-side features RIBs and Screw Bosses for a given drill handle.
Overview: Creating the class B and class C surfaces to the door handle and creating the B side features (RIBs and Screw Bosses) by considering all the design parameters.
Design parameters to create RIB for a plastic component:
Design parameters to create Screw Boss for a plastic component:
Tooling Axis:
To create the tooling axis, I extracted the surface of class A with no propagation and I created the point at the centre of the extracted surface and created a line at that point in the Y direction. After creating the Tooling axis, I performed a draft analysis for class A to check the draft angle for it.
Draft analysis for class A surface:
To perform the draft analysis in class A, I selected the featured draft analysis tool in the Generative shape design workbench. Initially, I click on the 'use of the compass to define the new current draft direction' command to align the compass to the tooling axis.
Once the compass is aligned the compass to the tooling axis, we need to select the surface to perform draft analysis. Class A surface will be highlighted (in green colour) according to the colour bar angle and colours we defined in it.
Here I gave green colour for > 0.9 deg, red colour for < 0deg>
If I gave a 3deg draft angle some faces are not getting cleared, so I have gradually reduced the draft angle to up to every face gets cleared.
When The draft angle is 3deg:
To clear the faces which are not cleared with a 3deg draft angle, I gave a 0.9deg draft angle to clear every face.
When The draft angle is 0.9deg:
Class B surface Creation:
To create the class B surface for the door handle, I offset the class A surface to 2.5mm inside. Once the class A surface is offset created, according to the thickness, we can observe some patches on the offset surface due to the fillets on the class A surface. Now, we need to close those patches. I used a multi-section command to close the patches.
Class A offset:
I have observed only one patch on the offset, I used a multi-section solid command to close the patch to create the proper 'Class B surface'.
Class B Surface:
Class C Surface creation:
I used the sweep command in the geometric shape design workbench to create the class C surface.
Initially, I extracted the edges of the class A surface with tangent continuity by using the multiple extract command. After extracting the class A surface edges correctly, I swept the extracted edges at 93deg toward the class B surface. After sweeping the extracted class A surface edges, I extrapolated the edges of the sweep for 2mm to intersect the sweep edges with each other. Now I trimmed the extrapolated surfaces together to create a complete sweep surface towards the class B surface. I joined both the trimmed sweep surface and class A surface together, to get the class A+C surfaces as a single surface. Now, to create a solid body for the door handle we need a closed surface. I trim the class B surface with joined class A+C surface to make the closed surface of a door handle.
Class C surface:
Class A+C:
Closed Surface Body:
Creating a Solid body:
To create the solid body I used the closed surface command in the part workbench. Click on the closed surface command in the part workbench and give the closed surface as an input to create the solid part body.
Solid Body:
RIB Design:
To create the ribs on the solid part body, we need to follow the above-mentioned design guidelines. Initially, I create a line sketch for the rib and I extruded it in the tooling axis direction and I thicken the extruded surface to 1mm toward the inside,
after thickening the extruded surface I gave 0.5deg of draft angle to the rib, and I union trim the rib with the part body to remove the extra surface of the rib, by union trimming the rib with the part body the rib gets added to the main part body without the unwanted extra part. After adding the rib to the part body, I gave the fillet to the rib with a radius of 0.25mm (as per the design parameters 0.25mm is the maximum fillet radius). In the same way, I created the rib-2.
RIB sketch:
RIB 1:
RIB 2:
RIB Root Thickness:
To check the rib root thickness, I created a plane which is perpendicular to the base surface (if the plane is parallel to the base surface the intersection will be taken, but we can't see any rib intersection on it, so that is why the plane is created perpendicular to the base surface). After taking the intersection for the body and plane, we need to create a tri-tangential circle at the bottom of the rib. To create the circle, we need to extract the faces of the intersection (if we directly select the faces without extracting the required faces the input may take the entire intersection surface as input) which we need to give as input for the tri-tangential circle. The tri-tangential circle is shown below, with its measurement of it.
SCREW BOSS Design:
To create the screw boss, I created the circular sketch in the sketcher workbench and I padded the sketch to 12.5mm. Now, I drafted the inside and outside surfaces with 0.5deg in the tooling axis direction. After creating the screw boss, I gave 0.25mm of the fillet to all sides. Now, I translated the screw boss toward the right side for 35mm. To keep the screw boss stiff and rigid, I created 4 supporting ribs for each screw boss.
Screw Boss sketch:
Screw boss Supporting Ribs:
DRAFT ANALYSIS OF THE SOLID PART:
- Draft Analysis at 3-degree angle: At 3 degrees some areas are not clearing so we have lowered the draft angle to 0.9 degrees.
2. Draft Analysis at 0.9 degrees: At 0.9 degrees some improvement is there in the component but still Ribs And bosses are not clearing because they are in 0.5-degree draft angle.
- Draft analysis at 0.49 degree: All the ribs and the bosses are clearing at 0.49 degrees except one area because in that area curvature is forming in the class C surface.
Different views of solid components: