Design of backdoor
Aim- Design BIW Tail gate (Back door) of passenger car through NX CAD 12.
Objective- To design the tail gate (Back door) of passenger car. The report constitutes about positioning of Latch and Striker, Wiper motor, Tail Light mounting, Gas stay reinforcements with suitable emboss definitions and Hemming flanges.
Back Door
Back door or Tailgate is an exterior body in white component that covers the Rear trunk space and houses vital rear mounting components like Gas stay, Wiper, Tail light, Hinge for opening and closing and holds design consideration like rear visibility, sealing flange, rear windshield mounting and crash resistance.
The back door is usually attached to the rear bow roof rail and opening and closing situation are carried by gas stay/power lifter mounting.
The component in tail gate design has
- Outer panel upper
- Outer panel lower
- Inner panel
- Hinge reinforcement LH
- Hinge reinforcement RH
- Gas stay reinforcement LH
- Gas stay reinforcement RH
- Wiper mounting reinforcement
- Striker mounting reinforcement
Design methodology
Design considerations
The styling surface is checked for surface integrity and irregularities are developed and saved for further surface Developments.
To improve the luggage, compartment the panel is drawn thinner with considerable space for all mounting parts and wire harness.
Material preference
The inner panel is made out of steel which is manufactured through deep drawn process hence reinforcements are essential to compensate the strength. At this time aluminium panel are used for casting outer panel which significantly reduces the weight and thickness can be varied along the panel without the requirement of reinforcement mountings.
Although with added advantages of Aluminium, steel drawn parts are used which is much cheaper than the former.
Tooling Direction
Based on the styling surface the foremost step is definition of tooling direction for deep drawn steel process and all downstream metal operations are based on tooling axis.
Latch and striker trajectory
To define the opening and closing trajectory, the hinge and latch are positioned based on the hinge axis and trajectory. The circle drawn should perpendicular to the latch striker to satisfy the condition. Based on the rotation trajectory the hinge axis, latch striker and predefined Gas stay are correlated for smooth kinematics of door opening and closing.
Emboss definition
Based on the load simulation the force acts in y and hence emboss are defined on the inner panel to dissipate the force outwards caused due to slamming of door and crash situations.
Emboss are defined and drafted along the tooling direction for feasible manufacturing and imparts strength to the panel without the need for increase in thickness.
Hemming
Hemming is a sheet metal joining process of inner and outer panel by eradicating the spot-welded areas which affects the aesthetics of outer panel. It is also a safety requirement for door handling along the edges and suitable relaxation are provided along the corners to avoid stress concentration.
Mastic influence
Apart from hemming the outer and inner panel are joined using mastic influence points to avoid the rattle noise and improve the NVH and trim part mounting points are provided which are usually snap fits.
Reinforcements
Reinforcements structures are provided to compensate the loss of strength on the embossed section of mounting points.
Draft Analysis
The draft analysis shows that the drafted section of inner panel are above 5 degree and are feasible for deep drawn process
Outer pannel upper
Outer pannel lower
Back door inner panel
Complete assembly of back door
