Design of backdoor

Aim:
The main aim is to design the Back door of a car from scratch following the design parameters using CATIA V5.
Theory:
Back Door:
The back door is placed at the rear end of a car at which the loads can be kept. It is also called a trunk or tailgate. It consists of an outer panel, inner panel, and some reinforcements to give strength to the component. Trunk lids are made of steel which is stamped using the deep drawing process. The thickness ranges from 0.6-0.8mm for the panels.

Components to create:

• Outer Upper panel
• Outer Inner PanelInner Panel
• Hinge Reinforcements (LH and RH)
• Gas Stay Reinforcements (LH and Rh)
• Latch Reinforcement

Procedure:
1. Checking the Geometry:
Once the model is opened, we get a Class A Surface of the back door.

• Try joining the Upper surface of the car, if the surface joins we get the outer surface and if the surface didn't join then we need to create the surface by using Multi-section surfaces.
• Create the fillet areas, Tail Lamp area as those areas will be vulnerable and are unable to join together.

2. Creating the Tooling Axis:
Click on the line option and select the Bisecting option.

• Now, Right Click on the 1sLine option to create a line. Select the point from the Vertex of the Upperside of the corner to the position where the declination starts. Click ok and the line is created.
• Now, click on the Second Line and follow the same procedure but from the lower surface. Click Ok and the line is created.
• After clicking ok, the bisecting line is created.
• You can also use a Point and direction method to create a tooling axis.
• The line created is the main tooling Axis.

3. Creating the outer Panel Upper Surface:
To create the Upper panel, the areas that are created before need to be joined together. Once those are joined the hemming
needs to done.

To perform Hemming, offset the present surface to 2.65mm (Outer Surface ThicknesS- 0.75mm, Ihner panel thickness- 0.75 gap between Outer and Inner panel-0.2mm, Hemming area bent region- 0.75mm, the gap between hem and Inner panel- 0.2mm)

use parallel curve 1omm to create the surface

use the multisection option to make hemming

to create an outer pannel, extraction of the lower end of the upper part needs to be done offset it to 0.2

4. Creating the Outer Panel Lower Surface:
To create the Lower panel, extraction of the lower end of the upper part needs to be done Offset it to 0.2mm and extrapolate the lower panel and the 2 surfaces. Now give an edge fillet of 3.5mm. Offset th created surface to 2.65 to perform hemming To perform Hemming, offset the present surface to 2.65mm (Outer Surface Thickness- 0.75mm, Inner panel thickness-0.75 gap between Outer and Inner panel - 0.2mm, Hemming area bent region-0.75mm, the gap between hem and Inner panel- 0.2mm)

use the sweep option to create an sweep with degree 25 t tooling axis

Similarly, create the lower side surfaces using the connect option and trim them.
Give the fillet value of 5mm to the corner surfaces.
A mastic point needs to be created. Create a Sketch of rectangular shape and provide a cut out on the surface. Now, use the sweep option to create the surface perpendicular to the base surface.

8. Generating a solid:
Go to the Part design, Create a New Part Body for the Upper part, Lower part, Inner panel, and reinforcements (each for Hinges, Latch, and Gas stay) Use the Thick surface option to create the solid with thick of 0.75mm for back door parts

Result:
The Back door of a car is created along with the necessary reinforcements that help to improve the strength and stability of the back door.
Upper Surface:

Lower surface:

Inner surface:

Terms Used
Hinges:
A hinge is a mechanical bearing that connects two solid objects allowing a limited angle of rotation between them. Two objects are connected by an ideal hinge rotate relative to each other about a fixed axis of rotation.
Latch:
The latch is a mechanical fastener that joins two or more objects or surfaces while allowing for their regular separation. It engages another piece of hardware on the other mounting surface. Depending upon the type and design of the latch, this engaging bit of hardware is known as a keeper or striker.