Challenge

Design of backdoor

MMeghanadh Sai Sivalal Agarwal25 Jan 2023

BACK DOOR:-

INTRODUCTION:

The Back Door of a car is the rearmost part of the vehicle which gives access to the trunk space of the vehicle. The rear door also supports the reinforcements and added weights of the Wiper Motor, Gas Stay, Tail Lamp, and Latch and Striker.

The Backdoor/tailgate is one of the closure commodities in BIW sheet metal design The backdoor has a lot of components inside and is designed to incorporate them easily. It affects the rear visibility and luggage area.

The material used for door manufacturing depends on the budget and performance of the vehicle. Mostly Aluminium and Steel will be used whereas low-budget vehicles use Steel which makes the manufacturing process easy and cost-efficient since it follows the Stamping of Moulds.

Major Parts and Reinforcements:

The backdoor consists of the following basic components:

Backdoor Outer Panel (Upper)
Backdoor Outer Panel (Lower)
Backdoor Inner Panel
Hinge Reinforcements (LH & RH)
Gas-Stay Reinforcements (LH & RH)
Latch and Striker Reinforcement
Wiper motor Reinforcement

TAILGATE:

Tailgate is a door at the back of a truck or car, that is hinged at the bottom so that it open downwards.

DESIGN INTENT

The intent of the project is to design a Body In White Back Door of the vehicle considering the engineering standards and manufacturing requirements which satisfies the Deep Drawing Process.

DESIGN CONSIDERATION OF A BACKDOOR:

Functional Requirement of Hinge and gas stay
Rear visibility criteria
Luggage volume
Crash Analysis
Bend Test, Dent Test, Torsion Test & Endurance Test
Rear Crash Regulation
Gap and flushness Requirements

DESIGN OF BACKDOOR OUTER PANEL:

The Outer Panel is the styling surface of the back door. Other components of the backdoor are designed with reference to the outer panel. It acts as the outer cover and deals with the aesthetics of the car.

In this design outer panel is divided into two parts

Outer Upper Panel
Outer Lower Panel

Outer Upper Panel:

The Outer Upper Panel Extracted from a styling surface.

The panel is altered for the required design with the surface tools of NX CAD

The thickness provided for the outer panel is 0.75 mm

Hemming is provided with the corner relief.

Outer Lower Panel:

The Outer Upper Panel Extracted from a styling surface.

The panel is altered for the required design with the surface tools of NX CAD

The thickness provided for the outer panel is 0.75 mm

Hemming is provided with the corner relief.

DESIGN OF BACKDOOR INNER PANEL:

The Inner Panel Extracted from a styling surface.

The panel is altered for the required design with the surface tools of NX CAD

The thickness provided for the outer panel is 0.75 mm

After creating the tooling direction the design of the inner panel will begin where we will first develop an effective sealing flange by checking all the boundaries and by following the shape of the inner panel design. By creating multiple flanges and by using surface modeling techniques the concept design of the inner panel was created.

After the concept of the inner panel is developed, then the child components like a hinge, latch, gas-stay locations, and their reinforcements must be designed. Which completes the overall design of the tailgate.
The embosses were created in ‘V-Shape or Y-Shape’ so that if the vehicle undergoes the crash then the force dissipates over it which reduces the damage transferred to the trunk space.
HINGE, GAS STAY & WIPER MOTOR EMBOSS:

The Orange circle denotes the hinge emboss which was created using the datum plane and emboss feature in NX. It was also designed in a way that the emboss should have a flat surface for assembling the hinges using it.

The violet circle denotes the gas stay emboss which was created using the surface of the connecting flange.

The yellow circle denotes the Wiper motor emboss which was created using the surface of the connecting flange.

STRIKER POSITION:

The position of the hinge should be perpendicular to the latch when the latch and striker meets. The circle is drawn from the center of the hinge axis to find the path of the striker and positioned perpendicular to the path.

DESIGNING THE REINFORCEMENTS:

The thickness provided for all reinforcements is 1 mm.

HINGE REINFORCEMENT
GAS STAY REINFORCEMENT
WIPER MOTOR REINFORCEMENT
LATCH REINFORCEMENT.

All the reinforcements were created using the same method, first, the linked body was created separately for each with the help of extract geometry and then the required portion was trimmed out and then thickened.

Hinge reinforcement:

Hinges enable the opening and closing of the back door. One end of the hinge is fixed on the backdoor and the other end on the Roof, on both sides. Hinges can be placed outside or inside the backdoor.

The hinge reinforcements are added to compensate for the weak region due to the acting load over it.

Gas Stay Reinforcement:

Gas Stay is a device used for supporting the back door in its open position. Gas stay requires no manpower and is engaged into support position automatically as the back door opens. One end of the Gas Stay is fixed on the backdoor and the other end on the Body Side or on the Back door stationary area.

Embossing is provided at the Gas Stay mounting area to compensate for weakness and improve strength.

Gas Stay Reinforcement:

Embossing is provided at the Gas Stay mounting area to compensate for weakness and improve strength.

Wiper Motor Reinforcement:

Wiper motor reinforcement is created to mount the wiper motor assembly.

Latch and Striker Reinforcement:

The Latch & Striker forms the locking mechanism of the backdoor with the car. Due to regular opening, closing, and over slamming of the backdoor, there is stress developed in the Latch and Striker area. To compensate for the same, reinforcements are added in this area.

DRAFT ANALYSIS:

The draft analysis will be performed for the tooling direction created at first and checked that the model is suitable for manufacturing.
Then to get a complete green portion the necessary changes to the draft angle of the embosses were carried out by optimizing the model.
The Draft Analysis command enables us to detect that the part drafted will be easily removed or not.
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.

Views of the designed Back Door:

TOP VIEW: