Design of Backdoor or Tailgate Assembly
Design And Development of Tailgate Assembly
Theory - Back door or tailgate the rearmost BIW commodity in an automobile. The general purpose of the tailgate is to cover the boot space and provide safety to the rear of the car. Generally, the back door is supported upon the C pillar and roof of the car.
Fig. 1 - Car Back door
Material - The material selection for the commodity depends upon the cost of the project. Aluminium is better suited for developing the part as it can be cast and does not require Reinforcements for strengthening the part but, is costlier. steel panels are generally used as they are cheaper but require reinforcements. steel also tends to increase the overall weight of the car.
The general requirements for the tailgate are the same as that of the bonnet of the automobile with few changes.
In this project, we are going to develop the inner panel of the part from given styling data. And also will develop various reinforcements for the part.
Design considerations - Following things must be kept in mind while developing the tailgate part.
- Rear visibility Criteria
- Stress distribution for rear collision
- Reinforcement for Hinges, Gas stay and lock and Lock and sticker mechanism.
- weight of the part.
- Boot space.
Mechanisms - The hinges for the tailgate are mounted at the rear end of the roof part. The hinges are then fastened with the help of screws. Depending on the curvature the selection for hinges may vary. If the tailgate cause interference with the roof curvature a pantograph hinge can be used which can help overcome such problems.
2(A) 2(B)
Fig. 2, Picture 2(A) Shows a simple hinge, Picture 2(B) Shows hinge assembly with spring assist used in Land Rover.
Depending upon the Weight and Cost of the Vehicle. Spring-powered or Gas Struts can be used as lifting mechanism. gas struts are costlier then their spring powered counterparts but require less human effort to operate the mechanism. These days ever OEM provide Gas struts as standard in the vehicle.
3(A)
3(B)
Fig. 3, Above images show the Gas-powered Struts For Honda Civic
Part Development -
4(A) 4(B)
Embossing - Embossing is a metal forming technique in which a protruded shape is created on the sheet metal part or body. Embossing helps in increasing the local strength of the part. By creating emboss we can also divert the impact force on the part towards Hinges and C pillars to avoid fatal casualties during an accident.
In a study published in IRJET, the major impact force during a collision on Back door travels in the shape of Y character of English Language. that is why the shape of the major emboss design is developed as Y. To improve the local strength of the region.
Reinforcements - reinforcements as shown in Fig 4(A) are necessary to improve the local strength in the part. As removing material for Hinges and latch striker mechanism the strength of the part drops significantly. to overcome this issue we provide reinforcement at proper places. Generally, the reinforcements are welded after the panel is developed.
Mastic Sealant And Hemming - After developing the inner panel it is joined together with the outer panel with the help of mastic sealant and hemming process.
Mastic Sealant is a Silicon or rubber base adhesive substance which retains its elastic properties even after querying. it is highly adhesive in nature and increase the strength of the local region. generally, a butyl based variant is preferred by the automakers around the world.
Hemming is the process in which the edges of the outer panel is rolled flush over the inner panel. the process creates a seam joining both the panels together. During the hemming, process relief is provided at the corners to avoid stress concentration. Refer to Fig 5.
Fig. 5(A)
Fig. 5(B)
Fig. 5(C)
Final Assembly -
Link for part - https://drive.google.com/drive/folders/1S04eAZyDZWLvlC5VnHLeS6p2HtOHXSyx?usp=sharing