Back door

Aim:

Back door design in Siemens NX 12.0. The design includes inner panel, outer panel, hinge reinforcements, striker & latch reinforcement and gas stay reinforcement.

Introduction:

Back door is also referred as tail gate of a car. This provides access to the boot space or cargo. Some vehicles use CNG or LPG, such vehicle use cylinders which occupies boot space.

The "back door" of a car typically refers to the rear door or doors that provide access to the rear compartment of the vehicle. In most cars, this is the door at the back of the passenger compartment, and it can be either a regular hinged door or a sliding door in the case of some minivans. The back door allows passengers to enter and exit the rear seating area of the vehicle.

Back door is a complex part as it hosts indication lights, sensors, rear camera, and also necessary wirings. Back door should withstand certain amount of deformation during collisions. It is a design engineers’ duty to check all the feature feasibility and also provide strength to the component.

Design considerations:

·        Rear view visibility

·        Force distribution

·        Latch and Stricker position

·        Hinge position

·        Hemming and relief

·        Hinge axis

·        Tooling axis

Components to design:

·        Inner panel

·        Outer panel upper

·        Outer panel lower

·        Reinforcements:

o   Hinge reinforcements

o   Wiper motor reinforcements

o   Gas stay reinforcements

o   Latch and striker reinforcements

Design:

Backdoor outer panel:

Skin data is provided in .prt format. Given Class A surface has so many discontinuities. The whole surface is joined before working. The final output is saved as a new file to work on further. The created skin is the reference data for the whole project.

Reliefs are provided on the outer panel and lower panel surfaces.

The image below is the final output of the outer panel upper. The rectangular opening mounts glass for rear view visibility. The thickness of the outer panel is 0.75mm. It also has openings in the sheet metal for indication lights.

Backdoor inner panel:

Outer panel lower is another component in the backdoor. This usually has registration number of the car. The image given below is the final output of the outer panel lower.

Backdoor inner panel:

Unlike outer panel inner panel is one single sheet metal. Tooling axis is created before the inner panel design. The blue line in the image shows the tooling axis.

Several embosses are created for reinforcements, for hinge, gas stay, wiper motor and latch & striker.

Draft analysis on the inner panel is given below.

Mastic area is created on the inner panel. This joins both the outer and inner panel also provides strength and reduces NVH. Mastic sealants joins both the panels.

The final output of the inner panel is shown below. The thickness of the sheet metal is 0.75mm. The embosses are created on the inner panel is to improve its strength.

 

Reinforcements:

All the reinforcements are provided between outer and inner panel. Screw bosses are used in this case to host hinge assembly.

Wiper motor reinforcement:

Latch and striker reinforcement:

Trajectory:

A circle is drawn from the hinge axis on to latch & striker. The circle shows the opening and closing axis of the back door. This also helps in understanding the latch and striker placement.

Assembly:

All the parts created are saves as backdoor assembly in assembly workbench. Outer panel is constrained in the space of the coordinate system. With respect to the outer panel all the parts are constrained.

Conclusion:

A complete backdoor is designed in Siemens NX 12.0. The design includes outer panel, inner panel and all the reinforcements. Tooling axis is created. Hemming is also done on both the outer panels. Hinge axis is created and door trajectory is also created in the design.