Design of backdoor

AIM

To create and assemble the backdoor  inner panel and outer panel and their reinforcements by following the design rules.

SOFTWARE USED
SIEMENS NX CAD 12

INPUT DATA

The styling surface of backdoor has given.

BACKDOOR

• Backdoor is also called has an tailgate and trunks or boots.
• Backdoor is also one of the door in car but most of the backdoor which give access to open luggage compartment. Luggage compartment in the sense a extra space or storing area provided in car where we carry our luggage.

• In some of the car backdoor is give access to sit passenger on back of the vehicle. now a days this type of backdoor is rare

• In the most of the cars, these back door are operated with the help of gas stay which in turn reduces the effort required to lift the door.

• Some luxury cars have power spindle system which is open automatically without any effort of human by the function of an electric motor. This kind of system is also called a powered trunk lid system hatchback or station wagons are sold as 3 doors or 5 doors models. The  backdoor designed should meet the safety requirement of the rear collision.

LOAD CASES FOR BACKDOOR

The following load cases were under gone after manufacturing the Backdoor. They are

• Bend Test
• Torsion Test
• Abuse Case
• Dent Test
• Assembly Load case
• .Endurance

Bend Test:

The bend test is a simple and inexpensive qualitative test that can be used to evaluate both the ductility and soundness of a material. It is often used as a quality control test for butt-welded joints, having the advantage of simplicity of both test piece and equipment.

Torsion Test:

The torsion and beaming test are designed to check modified vehicles for the two main strength requirements of any chassis: torsional rigidity and beam strength..Torsional rigidity is a vehicle's backdoor ability to resist twisting under applying load to the backdoor. Beam strength is the strength of the backdoor along its length. To conduct torsional test, hinges and striker position were constrained and the gradual load is applied at the down end of corners.

Abuse Cases:

Abuse cases are Over slamming and hanging when the door is in open condition.

Dent Test:

Dent test is a test, when the load applied to backdoor and after some point checking the door retracts to its original position or not.

Assembly  load case:

Assembly load case is a case, while assembling the vehicle the force is applied to the backdoor and checking whether the load is withstanding or not.

Endurance Test:

Endurance test is a workability test. This test is conducted by open and closing of backdoor to 'n' number of cycles, where at last we check the door behavior at the end of the cycles.

DESIGNING OF BACKDOOR

BACKDOOR INNERPANEL

Inner panel is component of backdoor which is the strengthen component. it provide access to all  accessories like sealing flange, hinge reinforcement ,wiper reinforcement, gas stay reinforcement and striker. Embosses are created to give more strength for inner panel. The Y and V shaped emboss are created against the wind direction.

Sealing flange creation

The sealing flange should maintain minimum value of 15 mm to maximum of 30 mm to but with rubber beading to avoid water & Dust enters inside the car.

Hinge reinforcement

Hinges support the weight of the whole backdoor. Hence a reinforcement are provided here too. Emboss is designed such that the hinges should operated freely. The electrical wiring looms are through the holes along the periphery to keep them hidden.

Gas stay reinforcement

An angled or Diabolic emboss is provided for the gas stay mounts. The angle makes it easy to be machined and stamped. It is reinforcement with a thicker sheet

Wiper motor reinforcement

A dedicated space below the wind shield is left for wiper motor. Emboss is created to give more strength for backdoor inner panel. Reinforcement is created for the assembly of wiper motor

Latch and striker reinforcement

At the bottom of the latch and striker assembly. Generally a key operated or automatic remotely controllable locking mechanism is used to keep the door closed and open.Another purpose of the emboss design is to distribute impact force towards hinges and latch assembly which are reinforced and can absorbed them.

The striker is created is perpendicular to hinge axis.

Manufacturing process

Metal Stamping

Metal stamping is a manufacturing process used to convert flat metal sheets into specific shapes. It is a complex process that can include a number of metal forming techniques are blanking, punching, bending and piercing, to name a few. Metal stamping is a fast and cost-effective solution for this large-quantity manufacturing need. Manufacturers who need metal parts stamped for a project generally look for three important qualities:

• High quality and durability
• Fast turnaround time
• low-cost

Types of Metal Stamping

There are three major types of metal stamping techniques

• progressive die stamping
• four slide stamping
• deep draw stamping

EMBOSSING

embossing is a metal forming process for producing raised or sunken designs or relief in sheet material 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.

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.

Characteristics of the metal embossing process include:

• Its ability to form ductile metals,
• Its use in medium to high production runs,
• The ability to maintain the same metal thickness before and after embossing,
• The ability to produce unlimited patterns, depending on the roll dies, and
• The ability to reproduce product with no variation.

MASTIC SEALANTS

A mastic sealant is a type of liquid sealant that cures in an elastic state, thus making it flexible while holding the bond of the surfaces that has attached together. It adheres to just about any material making an all purpose type of sealant.The main purpose of the outer panel is for the aesthetic looks. Thus we cannot use bolts or welding. This has to be done with the help of the hemming and mastic sealants. Mastic sealants are elastic compound that behaves like the rubber. It is placed between the outer and inner panel. Initially is it in paste form, but after the hot furnace bath it gets hardened thus joining the outer and inner panel. Mastic sealant has the tendency to increase the strength of the panel and has influence of 80mm diameter.

HEMMING

Hemming in automotive manufacturing is a cold process of joining an inner and outer panel by folding the flanges of the outer panel onto the inner panel, permanently clamping the inner panel in place. This process is used in the manufacture of doors, hoods, and decklids and can be accomplished using a traditional press or with a robotically controlled roller.

TYPES OF HEMMING

• Flattened/closed hemming
• Open hemming
• Tear drop hemming
• Rolled/rope hemming

Corning relief are created that the hemming is done without any stress relief on corners.

DRAFT ANALYSIS

Draft Analysis is done to check whether the part is manufacturable or not. The minimum draft angle is to maintain for sheet metal is 7 mm. The tooling direction for the analysis is perpendicular to the designed part.

• The section above which are all green is above 7 degree.so the section cleared draft angle
• The section blue is below 0 degree.we have to create separate tooling axis for that part.

• Now the tooling axis on z direction vector,so the section now is cleared.

BACKDOOR VIEWS

CONCLUSION

Thus the creation and assembly of the backdoor inner panel and outer panel and their reinforcements is created ans assembled.