Week 9 - Challenge 1 - Base Bracket Design
AIM: Create the Base Bracket Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class A Surface should be created meeting the requirements of the draft angle and at the end perform the Draft analysis on the model.
Class A is the surface created by the concept sketches made by free-hand sketchers. The finalized sketch is then fed to the computer and a 2D surface is created out of it using software like Alias. This mechanical design is known as a Class A surface.
Class B is a reference surface that is created by the design engineer and is a copy of the class A surface that is at a distance equal to the thickness of the part.
Class C is again a reference surface that is created by the design engineer to connect Class A and Class B surfaces also known as the side wall of the surface.
The technique that is used to create the model is to initially create a class B surface at a distance equal to the thickness(2.5mm here) and later a vertical surface class C. Then trim the three surfaces to obtain the required part.
Check the connectivity of the Class A Surface. Ensure that there is no gap between the component, using the join command. We can visually check it or by clicking the boundary command. It has 3 boundaries one outer and two inner circle boundaries. Therefore first check was completed.
EXPLANATION OF BISECTING METHOD: Bisecting method is used to find the proper tooling axis using the dummy tooling axis. In Bisecting method, the bisecting line is used which either bisects the two lines or it will show an error which means the two lines are parallel to each other. To know whether the particular surface is tolerable or not we intersect the surface with the respective plane and get a sketch that consists of two lines with the help of bisecting line option we bisect the line which creates a line at the midpoint of the two lines. Likewise, we create a tooling clearing axis for x and y which will be used to create the main tooling axis using the bisecting line option in the line command.
Steps involved in the creation of the aforementioned part
The first task to begin the model was to create the tooling axis. The model was observed from all the 3 planes and the xy plane was selected to create the part and so the hole was taken into consideration and a point was created.
Find the tooling axis of the component. The tooling axis is nothing but the mold opens or the cavity opens.
Check visually which is the best possible tooling axis. Check all three axes. Along x it is possible but expensive and y is not possible. z is the best possible tooling axis.
The 'green colour' represent the draft angle above 3°.
The 'red colour' represent the draft angle is 0°.
The 'blue colour' represent the draft angle on the negative side.
Therefore the main tooling axis is along the z-axis. Now perform the Draft analysis using the Featured Draft Analysis tool in the tools. Then after opening the draft analysis toolbox go for the compass and place the compass aligned to the tooling axis and click on the lock symbol after aligning and further click on the surface.
The same point was taken as reference and a dummy tooling line was created. This line was later used to create a plane to obtain the intersection pattern.
The two slopes on either side of the intersection were used to create two more lines and in the end, a bisector line was created which became the main tooling axis.
A geometrical set with the name base bracket was created and then the whole class A surface was separately extracted.
The same extracted surfaces were then untrimmed to get a complete surface and then extrapolated so that the trim command could be successfully performed.
2 sides at a time were trimmed to get the below surface which was offset to 2.5mm.
The same technique was used to create the other region which was identical to the first region as shown.
Initially extracting the right side rib using the extract option from Class A surface. Then perform Extrapolate in order to increase the length, Now trim the surfaces to the required surfaces, Then Offset the surface in order to get the required thickness. Similarly, create the left-side rib. Now Similarly get the slanted as well as the flat surface and offset it to the desired value And now trim in order to get the required surface.
The central region was also extracted and offset to 2.5mm.
The same region was used to trim with the aforementioned two patterns that were created earlier to obtain the required surface.
The surface B created is the exact copy of class A but at a distance of 2.5mm and without fillets so fillets with a value of radius+thickness of the part i.e. 3+2.5=5.5mm were given.
It surrounding region of the class was also extracted and extrapolated to trim the surface B with it.
The final surface created is shown below and is surface B.
The boundary was created by considering class A.
Sweep command was used and for reference, the main tooling axis and also the direction of the tooling were considered to create a class C surface.
In the same manner, the two holes on the sheet were also swept by creating the boundaries and later sweeping them both simultaneously.
The required 3 surfaces were joined together taking holes into consideration too.
All three surfaces were lastly trimmed to get the final part which is shown below.
DRAFT ANALYSIS
In plastic design, the draft analysis or angle that is considered in the OEMs is 3 degrees.
The first thing to carry out was to select the compass and set it on the tooling axis in the upward direction.
By clicking on the surface, the whole part turned into green color. If blue was visible that meant that the analysis was inversely done so just by flipping the direction, the draft analysis.
The hollow part was later created into a solid body by going to the part body option and then selecting the close body surface.
Draft analysis on the solid part resulted in green and blue regions.
The green region shows the part which is tolerable or producible by the molding machine and the draft angle is 3degree.
The blue color region states that the part can be allowed in some OEMs but still need to be improved for the other OEMs as the draft angle is more than 3 degrees.
The red color which is not there in this case states that the draft angle is less than 3 degrees and cannot be produced or if produced would be faulty.
ISOMETRIC VIEW
FRONT VIEW
SIDE VIEW
TOP VIEW
Conclusion: The Class C component is made into a solid part using a close surface and ready for the next stage process for adding engineering features like a boss, ribs, gusset, etc. as per the requirement.
ZIP FILE:
https://drive.google.com/file/d/1fW3O2CeRkInqP31iyeT_ZTWmvLnvh8YU/view?usp=sharing