Design of backdoor

Aim: To design a backdoor of a car using styling.

Theory:


Backdoor: This is an important component of the car assembly, it works on the mechanism of the lock and hinge mechanism in which one end of the door is fixed using the hinges and is free to move about the fixed axis.

Manufacturing of Car doors

1# Common Materials used for manufacturing Backdoor of cars:-

> Steel
> Aluminium

*Note: From the above-listed materials, on one hand, steel components are less expensive but require reinforcements for structural strength and are produced via a Stamping procedure, whereas
On the other hand, Aluminium components are expensive but it reduces the weight of the car significantly and is produced via Casting.




2# Manufacturing Techniques:-

a. Deep Drawing:- In this, a Punch is used to form the required surface on the sheet metal simultaneously a taper angle is given in the workpiece for easy ejection of the punch after the process.




b. Spot Welding: - In this, two electrode is used and a huge electric potential is created between the parts to pass current due to the resistance from the material fusion takes place and after the molten metal cools off small nuggets are created which are then removed via grinding.



c. Seam Welding: - This type of welding uses roller-type electrodes and the electric resistance of the parts to form continuous welds.



d. Lancing: - Lancing is a press operation in which a single line cut or slit is made partway across the strip stock, without removing any metal. As a result, the proper lancing engineering method prevents fracturing by improving the sheet metal flow.




3. Designing of Car Door: -

A. Major Design Considerations: -
> Rear Visibility



> Boot Storage



4. Approach of Designing: -

Below is the Top-Down approach used to make the Backdoor of the car


.
5. Design Software used: Siemens NX CAD: -

- Using the Assembly command, we first introduce the models and name them accordingly.
- Then via double- click we activate each part one-by-one
-At first, we need to check the surface irregularities and use the offset curve command and trim command to remove such irregularities.
- Moving on we use the command offset Surface in order to create the flanges for the sealing flanges.
- And using the Law Extension and trim & Extend commands proceed with building the surfaces.
- Below are the components made in the assembly of NX CAD software.

6. Components of Backdoor:-

> Backdoor outer Upper Part



> Backdoor outer lower part



> Backdoor inner



> Hinge reinforcements(a)
> Gas stay reinforcements (b)
> Latch and Sticker(c)
> Wind Shield Reinforcement(d)



7# Trajectory Circle:-

>For perfect bending and closure of the Backdoor within the given space without any interfering components and clashing between the components, it is necessary that the latch is placed at a point which lies at the line which is perpendicular to the centre of the common axis shared by the hinges.
Kindly refer to the below image for further clarification: -





> We proceed with joining the axis of the hinges and then make a circle which intersects the lower panel, following which we draw a tangent from the circle.
Now from the tangent we draw a perpendicular line in order to create the place for the latch and use the law extension and trim & Extend commands to make the surface.

8# Mastic Data:-
> Mastic is commonly used in between the inner and outer panels of the Backdoor as an adhesive and sealant. It is a popular choice where one surface needs to adhere to another in a durable bond, or where the area needs to be protected.

> Mastic are used because of its water-resistant, temperature-resistant and UV-resistant properties. It is also capable of resisting corrosion which makes it suitable for use with metals used in the manufacturing of Backdoor.

9# Hemming Data:-

-Upper Panel



-Lower Panel

> Purpose of Hemming:

• Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to achieve a tight fit.
• Hemming operations are used to connect parts together, improve the appearance of a part and reinforce part edges

10# Reliefs provided in the design:-

The Outer upper panel relief is provided as follows: -



The Outer lower panel relief is provided as follows: -





11# Draft Analysis:-

> As above stated that Back Door Manufacturing uses the Press Forming Manufacturing techniques for Steel, hence Draft angle plays a significant role in the procedure, hence all the components are tested in NX CAD for the appropriate draft angle (Minimum 7 deg for Steel), hence by proving the Draft reference angle we are able to analyze the components that whether they are able to be manufactured or not. And below are the Results: -




12# Embosses: -

Embosses in the inner panel was created by taking the tooling direction as the reference vector, so the tool can be easily extracted after the stamping operation.




# Result:-

A backdoor is an essential component of the car which ensures safety from rear collisions as well as provides a safe compartment to keep the luggage locked inside of the door without compromising the rear visibility.