Design of backdoor

BACK DOOR:

Aim:

        To design a back door of the car on sheet metal using the provided styling surface to come up with a back door design, use appropriate design methodologies, and provide the necessary reinforcements and embosses.

Objective:

• To design a back door of a car with an inner panel, outer panel and reinforcement for hinges, gas stay, wiper motor and latch striker.
• The inner panel is subjected to the draft analysis to ensure whether it is satisfying the deep drawing requirements for the tooling direction that is created in the design.

Introduction of Backdoor:

        The backdoor of a car is a component which hinges at the back of the car to cover the boot space or luggage area, but there are more functions that come with it which has to be considered while making a design of the same like rear visibility criteria and boost space. This part is usually designed keeping the master section of the rear roof rail because of the sealant flanges and also various other consideration, as it is also in contact with the side body of the air.

        It has back lights or tail lamps and braking lights which is termed as "third brake light" mounts on it, rear windshield fixes between inner and outer panel, in some back door spare wheel can be mounted on it, sometimes car registration number plate mounts on it and it gives a complete closed design to the car.

Design consideration of Back Door:

• Visibility Criteria
• Force Dissipation
• Latch and Striker Positions
• Hinge Position
• Gas Stay Position
• Hemming and Relief Areas

Components of Backdoor:

• Inner panel
• Outer panel Upper and lower
• Hinge reinforcement LH / RH
• Gas stay reinforcement LH / RH
• Wiper motor reinforcement
• Latch Striker reinforcement

BACK DOOR OUTER PANEL:

        In this design back door is created as two different parts back door outer panel upper and lower. This outer panel designed based on visibility criteria and proper reliefs provided at the corner for hemming operation. The thickness of outer panel is 0.75mm.

BACK DOOR INNER PANEL:

        Back door outer panel designed based on hinge, gas stay, wiper motor position and reinforcement as well as visibility criteria. Suitable tooling direction is creaed for trouble free manufacturing process. In this design stamping operations created based on this tooling direction. Embosses are provided in this design for force dissipation. In this design appropriate clearance given in mastic areas. The inner panel thickness is 0.75mm.

MASTIC AREA:

        Mastic sealants used for joining at outer panel and inner panel. It increase the strength of back door and good NVH. So accurate clearance given for mastic sealant. The mastic points are defined on the back door inner panel where the back door can easily deform. They help the back door outer panel to come back to its original shape after it gets deformed. Mastic sealants are elastic component that believe like the rubber.

        Then, the sheet metal will bend with the hepled of another die to make the flanges in "L" shape. Thus, the flange will have somehow same design and the length will completely depend on the cutout, if we need more length of flange, then we need to cut more sheet.

EMBOSSES:

        The embosses are used to increase the strength of the back door. 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.

HINGE REINFORCEMENT:

        In this design hinges are provided on the top side of the door. Appropriate reinforcement given for  hinge mounting areas to improve the strength.

GAS STAY REINFORCEMENT:

        Gas stays are support the weight of the back door while they are open. More load act on this region, so suitable reinforcement provided for better strength. It is spot welded on the inner panel.

WIPER MOTOR REINFORCEMENT:

        In this reinforcement is provided for this region to fixing the wiper motor on the back door.

LATCH AND STRIKER REINFORCEMENT:

        The striker is designed to create a tight fit between the door and the seal on the cab. The door open and shut several times in a day. So more force accting on this area. The reinforcement given in the latch and striker mounting area to increase the strength. It is spot welded on the inner panel. All reinforcement parts spot welded on the inner panel for better strength on that area.

STRIKER TRAJECTORY:

        The trajectory is created to position the latch and striker. latch system must be able to catch the striker of the door the while closing. Circle is drawn from the hinge axis. The striker follow this path.

HEMMING:

        Hemming is a mechanical joints design which is used for joining inner and outer closure panels as found indoors, hoods, bonnets and lifts gates. To increase crash resistance the gap between the hemming panel is filled with a high strength adhesive which also prevents from corrosion. In this design 0.2mm clearance provided for hem glue.

        Hemming relief are cut outs which are provided on the hemmed corner of the panel assembly which in turn to avoid some of the hemming defects such as wave - like or wrinkle formed surface. 

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 analysis 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.

VARIOUS VIEWS OF BACK DOOR:

CONCLUSION:

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