Door Arm Rest Week 8 Challenge

AIM :

To Create the Door arm rest component through the given Class-A surface by taking the Thickness of the component to be 2.5 mm. 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.

OBJECTIVES :

• Checking continuity of class A surface.
• Deciding feasible tooling direction & creating tooling axis.
• Performing draft analysis on class A surface.
• Creating class B surface from given class A surface.
• Creating class C surface to join A & B class surface.
• Creating solid feature by using closed surface.
• Performing draft analysis on final plastic component.

NOTE : Due to the special requirements of a product, the mold release direction of a particular part may not be consistent with the mold opening direction of the injection molding machine (product undercut), the slider, also known as slide, is a mold mechanism that is developed to solve the issues with the undercut. The basic principle is to turn the vertical movement of mold opening / closing into a horizontal motion. In order to cope with the situation that the undercut is located in the core or cavity, different structural forms are developed.

THEORY :

Armrests are one of the most comfortable inventions of mankind. Just like our legs and back, our arms also demand comfort and hence, armrests come in the picture. Initially, the idea came up to be used in chairs however, it gradually made its place in other areas as well where arms are at work. But now it is a quite prominent feature in modern cars. The potential reason is that while driving a car, the driver’s hands are continuously at work and he tends to get tired at some point. Therefore, it is very essential to give his arms some kind of rest during traffic or red-light or while driving on the highway. It led to the invention of car armrests. The driver can occasionally rest his/her arms while he/she is not occupied or driving slowly.

fig:plastic door arm rest component

In cars, there are generally two types of armrests:

• Front armrest: The front armrest is also known as the central armrests and it can be folded according to the preference of the driver. It often includes a separate compartment where bottles or cups can be kept. As technology is improving you can even find certain functions along with it such as window motors, controlling temperature and much more. At times, you will find such armrests attached to individual seats all well. Other similar armrests are often attached with the door of the car working as handles.

• Rear armrest: This armrest is attached on the backseat and is again foldable. This type of armrest can also be used as extra seating. In a few models, this armrest also acts as a safety seat allowing it to be folded doubly along with a seatbelt, generally, for children. Just like, front door armrests, you will also find similar armrests on the rear doors.

image source : yandex.com

image source : screenshot of class A recieved from styling team

Benefits of a Car Armrest ;

Armrests can be a great asset for your cars and there is a reason why people buy them especially if they are absent in their car. Here are a few benefits of car armrests:

• Armrests are a great way to give occasional rest to your arms and are best when you are on long drives because your arms will definitely need support during such long journeys.
• Armrest is a great way to add on some extra space in your cars as they generally have small compartments in them where you can keep food and/or beverages.
• Armrests which are attached at the front and rear doors work as handles and can make it really convenient to open and shut doors.
• Rear armrests act as an extra seat and make space for at least one other person.

PROCEDURE :

We will be recieving a styling class A surface from styling team who deveopes it from a concept sketch to aesthatic class A with styling software for eg:ALIAS.here our work is to get the class A and import it to the design tool to develop Class B & C surfaces.

Firstly,we have to check continuity of given class A surface to ensure class A surface is properly joined or no discontinuity present. This can be done by using join or boundary command in CATIA. By looking visually in below image we see that surface has continuous connected boundary as highlighted by green line. Also this boundary separated into two domains.

• Creating class B surface from given class A surface.

After checking the connectivity we will get into surface workbench to create a solid part having 2.5mm thickness from the given A surface, i.e the B and C surface had to be constructed. The B surface was constructed by extracting all the flat faces on the A surface. Once all the faces were extracted, untrimmed, extrapolated, and were trimmed to give a surface similar to that of the A surface. The surface was then offset by 2.5 mm in the direction where B surface was needed.

The next step was to add fillets to the B surface. In order to this, the fillets on the A surface were extracted and untrimmed and were measured using the Measure Item tool. Once the fillet values were known, it was possible to add them to the B surface.

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• Creating tooling axis for draft analysis :

Now we will be creating a tooling axis for the given surface model. The tooling axis helps determine the direction along which the mould will open. First, a point was created on the center of the surface(highlighted in green) and the two opposite surfaces(highlighted in blue) were used as a reference and a line was created which bisected the two surfaces. This line was again bisected using the third face and a tooling axis was created.

Creating main tooling axis & slider direction:

• First extract the base surface & create point on that surface. Insert axis system at that point. Take intersection of class A surface with the XZ plane of axis system. Create two lines along the vertical faces. Create line using bisecting method & passing through that point.
• Perform draft analysis using that line as tooling axis. We observe that few faces of component are not in green. So tilt compass like wise to achieve entire top surface & back surface are in green color except pocket surface. Lock the position of compass.
• Create the line in by choosing direction as compass direction & passing through point on base surface. This is our main tooling axis. After that unlock compass & reset it.

Likewise follow same process & create slider direction. Extract the vertical rib face & create point on it. Draw a line through point & normal to that surface. Perform draft analysis by aligning compass to that line. Make all pocket surface color green with help of compass. Lock the compass direction. Modify line direction. This is slider direction.

• CLASS-C :

In order to construct the C surface, a boundary was created using the Boundary tool and the A surface was used as a reference. A surface was created using the Sweep tool-draft option, and the tooling axis was selected as the draft direction and a draft angle of 3 degrees was given. The A surface was extrapolated by 2 mm using point propagation and all three surfaces were trimmed in order to obtain the final part body.

• Performing draft analysis on final plastic component.

Now,draft analysis was carried out on the final body by inserting a Feature draft analysis. It was important that the part body was in customize view with material mode on. The first step was to turn on the compass option and to drag the compass and place it on the tooling direction in the correct orientation. Once it was placed, it has to be locked in that position. Then an 'x' cursor appears as we hover over the body and by clicking on it, the draft analysis is shown. The color code was red - negative, blue 0-3 degrees, and green above 3 degrees. Three degrees were chosen since it is the ideal draft angle for plastic components. The body was green which meant that it was a good design and that it would not cause any problems when the part is being extracted from the mould.

Below i have attached the Screenshots of the Draft analysis report for the final plastic component

here i have Used the Close Surface feature to make a solid body from the surface.

fig:Draft analysis using main tooling axis in different views

fig:Draft Analysis with side core tooling axis in different views

Note : before submission of model i make sure that i have included all the things are listed below

• Ensure Proper Tree Structure
• Geometrical sets should have a proper name based on the sketches present inside of it
• All the sketches should be created under the Geometrical set
• Use the Close Surface feature to make a solid body from the surface.
• Publications: Use the publication option and publish the below
  • Tooling Axis
  • Class A, B, and C surface
• Screenshots of the Draft analysis report for both the given Class-A surface and the final plastic component
• Screenshots of the solid model with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)
• Submission as attachmentCATpart should be submitted as an attachment using the below Browse option.

RESULT :

By the end i have Created the Door arm rest component through the given class-A surface by following the operations that are listed below :

1. Checking continuity of class A surface.
2. Deciding feasible tooling direction & creating tooling axis.
3. Performing draft analysis on class A surface.
4. Creating class B surface from given class A surface.
5. Creating class C surface to join A & B class surface.
6. Creating solid feature by using closed surface.
7. Performing draft analysis on final plastic component.