Design of backdoor

BACK DOOR DESIGN

In this project I have are designed a back door for a hatchback car where it is hinged at roof level. Similar to the hood and side doors, back door is a swinging/closure commodity in a car. It consists of an outer and inner panel. It is a very critical component because of the passenger safety requirements.

 

Backdoor has to be designed by keeping in mind the space required for the luggage compartment as well as to accommodate the Latch and Striker motor and Wiper motor without compromising the strength of the component.

 

Usually Aluminium or Steel is used to manufacture the backdoor. While Aluminium backdoor is lighter in weight and has lesser number of components (since the part is "cast", it has varying thickness and therefore doesn't require reinforcements). Steel backdoor is "deep drawn" with uniform thickness, added reinforcements and therefore is heavier. But the production cost of the latter is lesser and therefore a Steel backdoor is priced lower.

The inner Panel is a component which is used for strengthening the door. It's thickness is in the range of 0.65-0.75 millimetres. It is one of the most important components on which all accessories are mounted like Hinges, Gas Stay, Wiper Moter , Latch and Striker etc.

The possible method is the integration method. In the integration method, the part is stamped out of a single blank. This reduces the number of tools needed the assembly cost and eliminates any fit ability problem.

There are many cases where the Inner panel is subjected to stress due to frequent opening and slamming. These stress and depression factors are compensated by features like embosses

The Outer Panel is the styling surface of the back door. It is the source of design of other parts of the back door, primarily the Inner Panel. The Outer panel of the back door is similar to other BIW components where it is the aesthetic part of a vehicle. The coating provided is of multi stage which has the property of scratch resistance, rush prevention and smooth and attractive finishes. The Outer panel also has the provisions for the tail lamp, rear fog lamp and also has the provision for license plate mountings. Most of the hatch back cars have the provision for wiper motor. It's thickness is in the range of 0.65-0.75 millimetres.

Hemming is the process of wrapping the flange of the outer panel to the flange of the inner panel so that they are fitting rigidly. After hemming process, the sealants were applied along the edge of the flange of outer panel so that water tightness is achieved. The below image shows the cross-section of the inner and outer panel joined by hemming process.

Usually, the reliefs were provided at the corners of the hemming flange to avoid the Hemming relief to avoid stress developed while hemming. stress developed during the hemming process.

While designing a component a design engineer must make sure that the component can produced by any means of manufacturing methods with least amount of time, material, manpower and power. So that we can reduce the overall cost of car.

 

When the Back Door is considered it is manufactured by deep drawing at most of the time Deep drawing is the process where the single sheet of metal is place over a die which has the desired shape of the final output and the sheet is pressed against it with a tool. For the tool to come out from the part usually pressing relief of 5° to 9° will be provided during modelling itself.

 

In NX draft analysis can be done after modelling so that we can verify whether the product is manufactured by pressing or not. One side of the surface is highlighted by green and other side by Red colour means that the model can be manufactured. Result of the draft analysis is shown in the figure below.

Thus the Back door was designed and developed from the given styling surface with essential Reinforcements and Emboss. To satisfies the manufacturing requirements Draft analysis was also done on the inner panel

The zip file is more than 20 and file couldn't be uploaded here and i created a word file and provided google drive link there

google drive link: https://drive.google.com/file/d/1eEzECFBQM7JlnGMv2wTC56J_dmSvhaBq/view?usp=drive_link