Design of backdoor
PROJECT TITLE : DESIGN OF CAR BACKDOOR.
OBJECTIVE : The main objective of the project is by using the provided styling surface to come up with a back door design, use appropriate design methodologies, and provide the necessary reinforcements and embosses.
INTRODUCTION :
The trunk or luggage compartment is most often at the rear of the vechical. Early desings had an exterior rack on the rear of the vehicle to attach luggage trunk. Later designs integrated the storage area into the vehicles body, and eventually became more streamlined. The main storage compartment is normally provided at the end of the vehicle opposite to which the engine is located.
Some mid-engined or electric cars have luggage compartments both in the front and in the rear. Examples include the Volkswagen Type 3, porsche 914, Porsche Boxster, Testla, and Toyota MR2. Rear-engined cars like Volkswagen Beetle or Porsche 911 have the trunk in front of the passenger compartment.
Backdoor of a car is also called tailgate. Generally a backdoor consists of inner panel, outer panel, different reinforcements, hinges, latch and striker etc. Car backdoor is mainly made of steel or aluminum based on the budget of a car. Aluminum backdoor improves the strength of the parts and also reduces the weight. As the aluminum parts are casted therefore we can vary the thickness of the parts hence we can aviod the reinforcements. While for steel parts we cannot vary thickness as the parts are stamped, therefore we have to provide reinforcements hence the weight of the backdoor increases.
DESIGN CONSIDERATION :
- Rear Visibility Criteria
- Suitable Embosses
- Different Reinforcements
- Hinge Axis Positioning and Latch and Striker trajectory
- Luggage area Space
- Joining Techniques followed like hemming, spot welding etc.
Rear Visibility Criteria :
While designing the inner panel and outer panel of a backdoor, the rear visibility criteria plays a major role because the cutout in the inner and outer panel is the deciding factor that how much area is visible through the backdoor wind shield glass.
Emboss Pattern :
Embosses are being provided in a structure to increase the strength of a part. In backdoor inner panel designY and v Shape Embosses are given because in case of collision these embosses will dissipate the forces away from the car.
Different reinforcements :
Reinforcements are provided in a designto compensate for loss of strength in a region or area due load acting there. In case of load acts in from of hinges, gas stay, latch and striker and wiper motor. Therefore required reinforcements are provided.
Hinge axis positioning and latch and striker trajectory :
Position of hinges and latch and striker plays a vital role in a tailgate design, because the position of hinges will decide the trajectory of the backdoor and accorfing to the position of the hinge axis we have to position the striker inn such a way that striker should always be prependicular to trajectory.
Luggage Area space :
In case the value of 't' will decide the luggage area. Larger is the value of 't' lesser will be the luggage area.
Joining Process :
Hemming :- Hemming is the process in which the edge is rolled flush to itself, while a seam joins the edges of two materials.
Mastic sealant :- Mastic sealant are made up of hard rubber, They are used to join the inner panel and outer panel. It improves the NVH. Mastic sealant are preferred over spot welding because it will be improve the aesthetics of the car.
Corner Relife :
During the hemming process, when giving the corner relife helps to control sheet metal material behavior and to prevent unwaned deformation during unbend operations and also helps to reduce the number of passes in hemming.
DESIGN OF BACKDOOR :
Outer Panel :
The outer panel is the styling surface of the backdoor. Other components of the backdoor are designed with referance 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 0.75mm. Hemming is provided with the corner relif.
Outer lower panel :- The Outer lower 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 thr outer panel is 0.75mm. Hemming is provided with the corner relief.
Tooling Direction :
Before designing the inner panel of backdoor the tooling direction for deep drawing purpose should be created. Then the styling surface needs to be checked and analyzed since it might have irregularities, hence it must be fixed first. Then the backdoor was designed using the top-down approach.
Design Inner Panel of Backdoor :
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 0.75mm. After creating the tooling direction the design of the panel will begin where we will first develop an effective sealing flange by cheacking 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 vehical undergoes the crash then the force dissipates over it which reduces the damage transferred to the trunk space.
Design of Reinforcement :
All the reinforcements were created using the same method, frist the linked body was created separately for each with the help of extract geometry and then the required position was trimmed out and then thickneed.
Hinge Reinforcement :
Hinges enable the opening and closing of the backdoor. 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.
Gas Stay Reinforcement :
Gas stay is a device used for supporting the backdoor in its open position. Gas stay requires no manpower and is engaged into support position automatically as the backdoor opens. One end of the gas stay is fixed on the backdoor and the other end on the body side or on the backdoor stationary area.
Wiper Motor Reinforcement :
Wiper motor reinforcement is created to mount the wiper motor assembly.
Latch and Striker Reinforcement :
The latch and striker froms 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 :
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. Draft analysis command enables us to detect that the aprt 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.
The mastic influence section and connecting flange needs seperate tooling direction.
CAR BACKDOOR ASSEMBLY :
CONCLUSION :
Thus using the provided styling surface backdoor is designed with appropriate design methodologies and provided the necessary reinforcements and embosses.
The Backdoor Design Model Link : https://1drv.ms/u/s!Aly1TzhZu9aOlHCeyyMrA4-Ihrf4?e=BzXrd1