Design of backdoor

• Rear Visibility for safety and functionality.
• Boot Space.
• Rear Crash regulations.
• Strength criteria.
• Draft Analysis.
• Support Structures like Hinge and Gasstay/Powerlifter.
• Mounts for the wiper motor and lights.

Different Sheetmetal processes used for manufacturing the Back Door:

Deep Drawing:

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

1. First-stage drawing: The blank shape of metal is placed on the die and in contact with the punch. When the metal specimen is a flat piece of sheet metal used in forming and finishing the product. Initially, the punch moves in a downward direction. The outer rim of the blank is subjected to pure radial drawing (drawing toward vertical axes) between the die and blank metal. The metal becomes bent and slides over the die and also stretched between the die and the punch. The metal in the vicinity of the punch head and contact with it bend and slide over radii and stretch over the punch head.
2. Redrawing: The components drawn from the first stage again it is redrawn and convert into more depth to form a cup shape in the die and punch. The second stage of drawing is called redrawing.

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. The metal sheet is drawn through the male and female roller dies producing a pattern or design on the metal sheet. Depending on the roller dies used, different patterns can be produced on the metal sheet.

Materials commonly used in the metal embossing process include:

• Aluminum alloys
• Steel alloys
• Zinc
• Copper
• Galvanized steel
• Brass
• Cold rolled steel

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, improve the appearance of a part, and reinforce part edges.

In car part production, hemming is used in assembly as a secondary operation after deep drawing, trimming, and flanging operations to join two sheet metal parts (outer and inner) together. Typical parts for this type of assembly are hoods, doors, trunk lids, and fenders.

There are various types of hemming operations:

1. Conventional die hemming: In conventional die hemming, the flange is folded over the entire length with a hemming tool.
2. Roll hemming: In roll hemming, the hemming roller is guided by an industrial robot to form the flange.

Open Hem: A Hem has a full round feature and a return flange. In open hem, the bend angle is equal to 180 degrees.

Teardrop Hem: In teardrop hem, the bend angle is greater than 180 degrees.

Closed Hem: Hems without any inside radius are called closed hem. Closed hems are not recommended if the hem geometry is to be painted or if the material used is SST or Aluminium.

Stamping:

The process of turning sheets of metal into a useful part or component is called sheet metal stamping. The metal is fed into a press, where the stamping tool, also known as a die, creates the desired shape. The die is pressed into or through the metal with tremendous force.

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 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.

Lancing:

creating a partial cut in the sheet, so that no material is removed. The material is left attached to be bent and form a shape, such as a tab, vent, or louver.

Load cases General analysis:

Design of Back door in NX CAD:

The door parts thickness is given below,

1. Outer Panel - 0.75 mm
2. Inner Panel - 0.75 mm
3. Reinforcements - 1.5 mm
4. Mastic filling gap - 5 mm

Components of Back Door :

The Components of the Back Door are as follows,

1. Inner Panel
2. Outer Panel
3. Hing Reinforcement
4. Latch and Stricker Reinforcement
5. Gas stays Reinforcement
6. Wiper motor Reinforcement

Given surfaces have to be repaired according to the smoothness. After repairing the surfaces, the door is divided into two parts Door Outer Upper and Lower Panels.

First, we need to create the Tooling direction for the Deep drawing operation. It shows that all the operations like embossing are done by considering this vector direction and it will help in manufacturing the part,

After that, we have to create Sealing Flange by offsetting the outer panel to the specified distance.

Then we will be creating the Back door inner panel flange by offsetting the outer surface at a distance considering the sheet thickness and thickening direction.

Then created the connecting flange to join the inner panel and sealing flange.

Then for the windshield panel mounting, the windshield panel is created and joined with a sealing flange.

Then to improve the strength of the inner panel and to reduce the weight emboss and other cut-outs are created. Also, for Latch and Stricker mounting cut-out is created. This cut-out is also done on another side of the inner panel to maintain the center of gravity of the Back door.

Another Emboss is created for Wiper motor mounting.

Another flange is created to reduce the vibration of the door by joining the inner and outer panels with the help of Mastic sealant.

Now to assemble the back door with the vehicle Hinges are used to open and close the door. For that to increase the local area strength we have to design the emboss and provide the appropriate reinforcements to withstand the load acting upon it.

Hinge Reinforcements:

For positioning the Latch & Stricker, we have to create a trajectory passing through a midpoint of the line/ axis of two hinge mounting holes,

Latch & Stricker Emboss:

Gas Stay Emboss and Reinforcement:

Wiper Motor Reinforcement:

Hemming and Hem Relief:

Draft Analysis of The Individual parts:

Conclusion:

I completed the Back door design with all design considerations and did the draft analysis.