Design and Development of Door Arm Rest

DESIGN AND DEVELOPMENT OF DOOR ARM REST WITH ITS DRAFT ANALYSIS

Objective:

The main aim of this report is to explain how the tooling axis was created for the given class A surface of a door arm rest design and the steps involved in draft analysis with respect to the created tooling axis. Following the draft analysis, then the detailed explanation on creation of class B & C surface regarding to the class A as follows with steps involved in solid part creation.

Description:

Door arm rest:

Door arm rest is a part which is incorporated with the door panel and it is considered as an Interior trim of the automobile. The main purpose of this door arm rest is to support the driver and the passengers arm position while travelling, it also contains a holder for wallet or mobiles. Some reference images are attached below,

Side view of a door panel and the blue color part is the door arm rest part.

Isometric view of the same door panel for clear understanding.

Class A surface:

The class A surface of a door arm rest design is given to do the draft analysis and then, to create class B & C surfaces out of it for solid part creation.

Isometric view of the given class A surface of Door arm rest.

Test-1:

In this test the surface continuity of the given class A surface is examined to avoid gaps. If any gaps or discontinuity is present in the class A surface, we cannot thicken or use closed surface command to create a solid part out of it.

Joining:

By applying joining command to the class A surface, we can test the continuity of the class A surface of the given door arm rest by examining its edges.

Boundary:

By applying boundary command to the class A surface of the door arm rest, we can create a boundary line of the open edges. With help of this boundary line the continuity is tested visually.

Boundary of class A surface shown in the above picture.

If any gaps or discontinuity in the class A surface is found we have to correct it for further process.

We can use either joining or boundary command for this test.

Test-2:

In this test, the tooling axis is created along the x, y and z directions, to choose the best tooling axis out of it, for reducing the tooling cost.

Intersect:

The class A surface is intersected along the yz plane and zx plane to create intersecting lines. With these intersecting lines we are going to take some reference for creating initial tooling axis along the yz and zx planes.

Tooling axis:

Tooling axis is used to define the direction of core and cavity movement of a moulding machine according to the component to be moulded.

Isometric view of class A surface.

For this given class A of Door arm rest, the tooling axis is created with the help of positioned sketch creation by intersecting the class A surface in zx and yz planes.

Class A surface along X axis, in this direction the pocket area with three drafted faces and a hole were not clearly visible. So, it is difficult to manufacture this component in X direction.

Class A surface along Y axis, in this direction the pocket area with three drafted faces and a hole were not clearly visible. So, it is difficult to manufacture this component in Y direction.

Class A surface along Z axis, in this direction the pocket area and other surfaces of the class A is clearly visible, including the hole and it can be easily manufactured in Z direction.

In this case, the tooling axis is created along the z direction. Also, it is cost efficient considered with other tooling axis. And there is no need for side core for this door arm rest design.

• By using the bisecting line command, a bisecting line is created with reference to those initial tooling axis lines and point were created previously. This bisecting line is considered as tooling axis.

Bisecting lines with reference to the point and initial tooling axis lines created is shown.

This bisected line is considered as the final tooling axis.

Final tooling axis is shown.

• This tooling axis decides the movement direction of core and cavity to manufacture the door arm rest part.

Draft analysis:

The draft analysis command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on color ranges identifying zones on the analysed element where the deviation from the draft direction at any point, corresponds to specified values.

Draft analysis is carried out to check the drafts in the class A surface of door arm rest is feasible. The nominal draft for plastic components is 3º and 0.5º is the minimum draft value.

• After the creation of tooling axis, the feature draft analysis command is applied to do the analysis.
• By using the direction tool, the compass to define the new current draft direction is placed along the tooling axis. Then the draft direction is locked.
• In the display tool, color scale is opened to give the limits for draft analysis and then the surface is selected to test the draft for the given limits. If the color of the surface is changed to green, then the draft of the component is able to be manufactured.
• If the color of the surface is changed to red, then the class A surface is failed in draft analysis test and it is difficult to manufacture the component in cost effective manner.
• In this case, the class A surface of door arm rest is passed in the draft analysis and the part body of it can be created for further process. Those small red color areas are neglected in this design to proceed further.

Draft analysis of the class A surface with nominal draft is shown in the picture.

Draft analysis of the class A of door arm rest is shown.

The same procedure is followed to conduct draft analysis on the solid part also,

Draft analysis of the part with nominal draft is shown.

Draft analysis of door arm rest is shown.

B Surface:

B surface are said to be the engineering surface which has all the ribs and fixing elements in it. This B surface is created with reference to the given class A surface.

• After completing the draft analysis, if the class A surface is passed then the class B surface creation starts.
• Extracted the necessary surface from the class A and untrimmed those surfaces to extrapolate it.
• After the extrapolation, trim command is applied to remove the unwanted surfaces.
• Then this surface is offset to the required thickness value and then the fillets were applied.
• This offset surface is said to be class B surface.

B surface shown in the above picture.

C Surface:

C surface are said to be the connecting surface of class A surface with the B surface.

• Boundary command is applied to the open edges of the class A surface to create a boundary line or multiple extract command is applied to extract the open edges.
• This boundary line or extracted line is used to create the sweep along the draft direction or reference to the surface with enough value to overlap the B surface.
• It is said to be class C surface.

C surface shown in the above picture.

Closed surface:

Closed surface is the final surface used to create the solid part by applying the closed surface command in the part workbench.

• After the creation of class A, B & C surfaces, they are joined and trimmed to form the closed surface (fully enclosed surface without any gaps).

Closed surface is shown.

Sectioned view of closed surface.

Solid part:

Solid part is created by applying the closed surface command in the part workbench to the closed surface which is created with the help of class A, B & C surfaces in the surface workbench.

Isometric view of door arm rest solid part.

Sectioned view of door arm rest solid part.

Conclusion:

The creation of tooling axis and the steps involved in draft analysis of door arm rest is explained in detail with respect to the reference images regarding to the given class A surface. And, the steps involved in class B & C surface and solid part creations are also explained in detail with some reference images.