Challenge

Design of backdoor

AAyan Ansari6 Dec 2022

Aim: To design a Bach door using the given A surface.

Software used: CATIA V5.

Introduction:

A back door is the opening provided for the boot or back part of the vehicle. These doors can be operated manually or electric powered. In luxury cars, it is elecronically controlled, whereas in lower range cars it is manually controlled.

It mainly plays a mojor role on rear crash scenarios, so the design must possess needed requirements.

Which overall includes the design of the trunk and material used, flenges, embosses, type of joining of inner panel and outer panel etc.

There are three types of backdoors based on their working positon:

1) Top Mounted:

2) Side Mounted:

3) Bottom Door:

-Types based on their working operations:

1) Electrically Operated:

There is a motor provided at the supports of the backdoor which gives it the power to be opened or closed by the sensors which collects signal from the key.

2) Gas stay:

This type is majorly used in economy cars to prevent high cost. It is a gas cylinder mechanism to push the backdoor open. We have to give the initial load to open the boot.

-There are some main parts to creat the backdoor assambly:

1) Inner Panel

2) Outer Panel

3) Hinge and its reinforcememts

4) Latch and striker with reinforcements

5) Wiper Motor hinge and its reinforcements

6) Gas stay Reinforcements

- Material Selection :

At first, in older days most of the manufacturers used steel to manufacture the backdoor. Steel is ductile enough to take the shape we require and also it is very strong.

But, Due to its heavy density it is very heavy and sometimes it is difficult to design the desired shape out of it. So, to overcome that problem, we use some alloys with aluminium. Aluminium is less denser compared to steel. Thus, reducing weight. Also it is easy for it to give any desired shape as it is less complex.

- We can see come comparison in below image:

Load distribution is one of the most important factor while designing.

- We can distribute all the load by designing embosses on the inner panel of the backdoor.

- Deep drawing is the most used manufacturing process.

The metal deep drawing process is an effective method of manufacturing of cups, cans and other similar deep drawing products. The deep drawings having two main categories.

-Embossing : Embossing is a metal forming process for producing raised or sunken designs or relief in sheet materials by means of matched male and female roller dies, theoretically with no change in metal thickness or by-passing sheet or a strip of metal between rolls of the desired pattern.

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. Normally hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges.

Blanking:

Blanking is a cutting operation of a flat metal sheet and the article punched out is known as blank. Blank is the required product of the operation and the metal left behind is considered as a waste.

Punching:

It is similar to blanking only the main difference is that, the hole is the required product and the material punched out from the hole is considered as a waste.

CLASS A surface:

This was the given class A for the backdoor. The snapshot provided it of after fixing the rough surface to smooth one. We had to check wether it it is thickening or not. We had to give it a thickness of 0.75mm.

Tooling Axis:

First we need to create a tooling axis according to our design.

Sealing Flange :

Sealing flange is an important part of the backdoor. It rests on the body of the rear of the vehicle. connecting woth the rear part of the roof.

Hinge assembly:

It is provided for the support of backdoor, to reduce the human efforrts.

Gas stay Assambly:

Gas stay is the mechanism provided to open the backdoor manually.

Latch and striker Assembly:

It should be designed in such a way that the striker should be tangencial to the trajectory circle.

-Reinforcements :

These are the reinforcements which are going to be mounted on the vehicle body.

Latch and striker reinforcement:

-Trajectory Circle:

It is an imaginary circle which is made at the mid point of the backdoor. It helps us for a better visualisation of the path of the backdoor while it opens and closes.

It should be noted that the striker must be tangent to this circle, then and then only it will be fix properly on the locking mechanism.