Design of backdoor

CAR BACK DOOR DESIGN

Aim: To design back door of car using given outer class 'A' surface.

What is back door of a car?

A door which is located at the rear side of a car which gives access for the boot space to store luggage, spare wheel etc.

These doors can be operated manually or electric powered. In most of the luxury cars door is electrically operated.

Gas Stay Powered:

Electric Operated:

Back Door Assembly:

• Inner panel
• outer panel
• hinge and its reinforcement
• wiper motor reinforcement
• latch & stricker and its reinforcement

• Inner panel
• outer panel
• hinge and its reinforcement
• wiper motor reinforcement
• latch & stricker and its reinforcement

Materials Selection:

The selection of material plays a major role in determining the overall weight of the back door. The common materials used are Steel & Aluminum. The density of Steel is higher than Aluminum thus adding more weight to the door. The material used in the manufacturing of the backdoor depends upon the budget of the car, most low cost vehicles use steel as it is cheaper compared to Aluminium. Another aspect to be noted is that, if casted Aluminum parts are used instead of deep drawn steel parts there is no need of reinforcements and the overall weight of the car is reduced by approximately 5-10kg thus increasing the performance of the vehicle. Also the draft angle for casted parts is around 3 degrees while for deep drawn parts is around 7-10 degrees which helps in increasing the luggage/ cabin space.

Design Consideration:

• Rear visibilities for safety and functionality
• Support structures like hinges and Gas stay/ Power lifter
• Rear crash regulations
• Boot space
• Mounts for wiper motor and lights
• Strength criteria
• Draft analysis

Creation of Tooling Direction:

Back door is going to be manufactured by deep drawing process. In deep drawing process has a tool which is core and Die. The core part follows the single straight path the inclination angle of the core is known as tooling direction. The tooling direction/axis is created so, that the manufacturing team take the reference of this tooling axis and manufacture the part accordingly. It is designed by using Top down approach.

Inner Panel:

The inner panel is a component which is used for strengthen the door assembly and it is one of the most important components on which all accessories are mounted like hinges, glass guide channel, molded trim, latch 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.

Outer Panel:

The outer panel of the back door is similar to the other BIW components where it is the aesthetic part of vehicle. The coating provided is of multi stage which has the property of scratch resistance, rust 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 hatchback cars have the provision for wiper motor.

Embosses & Reinforcement:

With the distinctive cross section, embosses are created. The embossed are used to increase the strength of the backdoor. While designing we should keep in mind that it should not be over strength. So we prefer to design big embosses rather than small embosses. These embosses are used to despite the forces sideways.

Gas Stay Reinforcement:

Hinge Embosses:

The backdoor is a swinging commodity, which swings with the help of hinges. This can be done by tentatively positioning the hinges and on the hinge axis, we take a center point. Again we take another center point on the latch hole. Taking these two points as a reference we draw a circle. This circle is the striker trajectory and it has to be perpendicular. This can be achieved by moving the hinge axis back and forth or by rotating the latch area.

Latch and striker trajectory:

To define the opening and closing trajectory, the hinge and latch are positioned based on the hinge axis and trajectory. The circle drawn should be perpendicular to the latch striker to satisfy the condition. Based on the rotation trajectory the hinge axis, latch striker and predefined Gas stay are correlated for smooth kinematics of the door opening and closing.

Wiper Mechanism Reinforcement:

Hemming Operation:

Draft Analysis:

The draft analysis command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the draft direction at any point, corresponds to specified values.

Minimum draft angle of 7 degree is considered for analysis, green color infers on the parts that all face along the tooling direction has positive draft angle greater than 7 degree and passed in analysis.

Screenshot Back Door Assembly:

Conclusion:

Thus the back door was designed and developed from the given styling surfaces with essential reinforcements and emboss. To satisfy the manufacturing requirements draft analysis was also done on the inner panel.