Design of backdoor

DESIGN OF BACKDOOR

1.0 AIM

To create a design for a back door, utilize the provided styling surface in conjunction with appropriate design methodologies, and ensure that the necessary reinforcements and embosses are incorporated to meet functional and aesthetic requirements.

2.0 INTRODUCTION

2.1 BACK DOOR

The terms 'back door' or 'tailgate' generally refer to the opening at the rear of a vehicle, which allows access to the cargo area or trunk. This opening is typically covered by a door that can be opened and closed. Hatchbacks, estates/station wagons, and liftbacks often feature a tailgate that is hinged at the roof. Depending on the vehicle, the cargo area door or opening may be hinged at the top, side, or bottom.

Traditionally, opening and closing the tailgate of a car has been a manual process that requires the driver to physically exit the vehicle and use the car key to operate the tailgate. However, modern automobile manufacturers are now offering advanced features such as automatic tailgates. With an automated tailgate, the opening and closing of the tailgate can be performed electronically, eliminating the need for manual operation.

3.0 MANUFACTURING PROCESS

Conventional tailgate assemblies are made from stamped metal panels welded together to form a tailgate. Latches are added on either side of the tailgate to engage a striker on the pickup sides. A handle operates the latches to open and close the tailgate assembly. Steel tailgate assemblies provide a durable and secure closure for the pickup bed.

Another disadvantage of steel tailgate assemblies is the cost of the tooling required and equipment required to stamp metal tailgate components. Metal tailgate components are generally produced in a large stamping press. The stamping presses generally require finely machined tools made from hardened steel. The cost of tooling a metal tailgate is much more expensive.

3.1 MATERIAL FOR BODY PANELS

The materials used for car body panels must possess specific characteristics to meet the challenges of the industry. These include rationalization of specifications to reduce inventory, improved formability to reduce rejection rates, and higher quality for better performance. One trend is the preference for higher strength low alloy (HSLA) steels of thinner gauges, which reduces weight and improves fuel economy. Other sought-after qualities include higher yield stress, toughness, fatigue strength, improved dent and corrosion resistance, and improved durability and reliability.

Achieving consistent quality of auto body skin panels during stamping requires meeting strict formability and ductility specifications of strip steels. Most of the steels used in automotive applications are aluminium-killed steels of around 0.7 to 0.9 mm thickness.

Intensive research and development efforts are focused on finding alternate materials, manufacturing processes, and stamping tools for sheet-metal components. The main goals are to reduce vehicle weight and unit cost. The steel content of cars is decreasing with the use of aluminium and other materials, such as plastics. Aluminium is particularly promising, as it can reduce weight by up to 30% while maintaining the same strength, stiffness, and stability as steel. Additionally, aluminium may offer cost savings in die production. However, challenges related to strength, serviceability, manufacturability, and cost must be addressed before aluminium can fully replace steel in body panel applications. Plastics are also being explored as a material for bumpers.

3.2 STAMPING PROCESS

The choice of stamping processes used for a panel is dependent on its design. Typically, blanking, drawing, piercing, forming, notching, trimming, and hemming are among the most widely used processes. Blanking creates the initial approximate form of the part in a flat sheet. Drawing is generally the first operation to achieve depth-related form. Piercing, notching, and hemming are operations specific to product design. Trimming is used to remove extra material from the periphery of the panel, which was added during the blank holding process of the draw operation. The decision on the trim line is crucial and can be the deciding factor in obtaining a good draw.

1. Blanking

When required, blanking is the first step of the stamping process. Blanking is the process of cutting larger sheet or coils of metal into smaller, more manageable pieces. Blanking is usually performed when a stamped metal piece will be drawn or formed.

2.Piercing

If a part requires slots, holes, or other cut-outs, piercing can be employed. Piercing, which can be performed simultaneously with blanking, punches the requisite shapes out of the metal sheet.

3.Drawing

Drawing is the actual stamping in the metal stamping process. A punch forces a section of metal through a die, providing the primary shape of the part. When the depth of the part is less than the primary opening, it is considered shallow drawing; parts with a depth greater than the opening are deep drawn.

4.Bending

Bending is a fairly self-explanatory process. The part-in-progress is placed on a specially designed die and a ram pushes against the metal, providing the required bend. Bending is performed after drawing, as attempting to punch an already bent piece of metal causes the entire part to deform.

5.Hemming

Hemming is a technology used by the automotive industry to join inner and outer closure panels together (hoods, doors, tailgates, etc.). It is the process of bending/folding the flange of the outer panel over the inner one. The accuracy of the operation affects significantly the appearance of the car’s outer surfaces and is therefore a critical factor in the final quality of a finished vehicle.

roller hemming :-The robotized hemming systems use a standard industrial robot integrated with a roller hemming head, offering a very flexible solution. This roller hemming head consists of a body, some guides and a number of rolls that are designed according to the geometry of the part in each case.

4.0 BACK DOOR DESIGN

The design consideration of back door are ,

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

PARTS OF BACKDOOR

• Back door outer panel (upper and lower)
• Back door inner panel
• Hinge reinforcements
• Gas stay reinforcements
• Latch and striker reinforcements
• Wiper motor reinforcements

1. 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 0.75 mm .

2.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 created 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 0.75 mm

Force dissipation

This inner panel design created by considering the force dissipation criteria.The embosses are created in such a manner that force will dissipate in to sides of the back door during a collision and prevent reaching inside the passenger cabin.Y and V embosses provided in the back door for force dissipation and improve the strength of the metal.

Mastic Area

Mastics sealants used for joining of outer panel and inner panel. It increase the strength of back door and good NVH. So accurate clearance given for mastic sealant.

Reinforcements in inner panel

Hinge reinforcement

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

Wiper motor reinforcement

Reinforcement provided in this region for fixing the wiper motor.

Latch and striker reinforcement

The striker is designed to create a tight fit between the door and the seal on the cab. The door opens and shut several times in a day. So more force acting 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.

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 follows this path.

Hemming

Hemming is a technology used by the automotive industry to join inner and outer closure panels together (hoods, doors, tailgates, etc.). In addition, adhesive bond provides for excellent joining of panels it also reduces vibration. here this design 0.2mm clearance provided for hem glue.

Proper corner relief provided for trouble-free hemming operation

5.0 Draft Analysis

5.1 Upper panel

5.2 Inner panel

6.0CONCLUSION

The backdoor is designed based on design considerations. Required reinforcement provided on inner panel. The design is checked by using draft analysis feature.