Design of backdoor
Aim: To design the Back door (Tail gate) of a car from the styling surface provided using NX CAD. The ultimate aim is to design the Back Door by following the Industrial Standards.
INTRODUCTION:
A back door is a BIW component found in all Automotive car generally used for opening and closing of the so called car luggage that is usually used for storing items inside a car. In general the opening and closing of the door is co-ordinated by the Latch and Stricker position and the Gas stay position that is mounted on the body and back door of the car. These positions play a major role in ensuring smooth opening and closing of the tail gate.
Parts of a Tail Gate:
- Outer Panel Upper
- Outer panel Lower
- Inner panel
- Hinge Reinforcements
- Latch and Stricker Reinforcement
- Wiper Motor Reinforcement
- Gas Stay Reinforcements
All these parts are assembled together to obtain the back door of a car.
Design Considerations In Back Door Design:
The following design factors were taken into account when creating the back door. It's them,
Visibility Criteria
Force Dissipation
Latch and Stricker Positions
Hinge Position
Gas Stay Position
Material Selection
Space Availability
Hemming and Relief Areas
All of these design factors must be taken into account because certain positions are dependent upon others, and if one position changes, all of the other positions must also change for the back door to open and close properly. In order for them to play a significant part in the opening and closing of the car's doors as well as the rear visibility requirements, the latch and stricker, hinge position, and gas stay positions must be maintained properly.
Force Dissipation:
The major criteria in designing the back door or any BIW part is the force dissipation during an impact or a colloision. Hence studies are being done inorder to dissipate the force on the sides and avoiding it reach the inner cabin of the car so that possible damage of imapct inside the car is reduced. Hence inorder to do that the V or Y embosses are created on the inner panel so that the force gets transmitted on to the sides instead reaching it on the cabin. This is one of the main criterias in back door design.
Thus from the above image it is clear that the forces are dissipated on the sides instead of reaching inside. This is the reason to have Y or V embosses on the panel to increase the stiffness and to dissipate forces onto the sides.
Latch and Stricker Positions:
The Latch and Stricker positions are crucial in determining how the back door opens and closes. As a result, the opening and closing of the had to be smooth, and the trajectory had to be tangent to the open close circle that is drawn, and the centre point of the latch and stricker had to be at the same point. This is depicted in the image below. Only if the centre points and tangent line are perfect will the back door open and close smoothly and clearly. Otherwise, the Hinge, Gas stay, Latch, and Stricker positions must be modified to accommodate the change.
The hinge and stricker centres are aligned in this case, and the movement's trajectory is clearly obtained.
Hemming and Relief Areas:
Hemming and Seaming are two similar metal working processes in which sheetmetal edge is rolled onto itself.Hemming is the process in which the edge is rolled flush to itself, while a seam joins the edge of two materials.
The Hemming is done on the outer and the inner panel with an clearance of 0.2mm on the either sides. Since at the corners the hemming is difficult to perform, clerances has been given at the ends of panels so that it would for the hemming operstion is performed. Here is the image of the hemming relief at the corners.
Reliefs are provided on the corners for hemming.
Outer Panel upper and lower :
INNER PANEL :
REINFORCEMENT :
EXPLODED VIEW :
