Design of backdoor

BACK DOOR DESIGN

OBJECTIVE :

• The main objective of this project is to design a back door of a car with an inner panel , outer panel and reinforcements for hinges , gas stay , wiper motor and latch
• The inner panel is subjected to the draft analysis to ensure whether it is satisfying the deep drawing requirements for the tooling direction that is created in the design

INTRODUCTION :

Design of any product starts from an requirement . The design engineer sketches the product based on the the requirement . Then the 2D sketch with the proper dimensions is converted into the 3D model using the advanced CAD software's . The another important thing in the design is that , every product that is designed should be able to manufactured . so the role of the design engineer is to design the product that can be easily manufactured and with less cost effective . This is the place where the Design for manufacturing [DFM] and Design of assembly [DFA] takes a role while developing any product . The process of development of design carries on until the design satisfies the customer needs .

Here in this project the product that we are going to develop is a car back door .

BACK DOOR INTRODUCTION :

The back door of the vehicle is also called as tailgate .The back door of the car is the rear most part of the vehicle which gives access to the trunk space of the vehicle .The back door is one of the closure commodities in BIW sheet metal design . The material used for the back door manufacturing depends on the budget and performance of the vehicle . mostly aluminium and steel is used for the manufacturing where as the steel is used on the low budget cars where it can be easily produced with less cost effective by following the stamping process

BACK DOOR PARTS :

The back door consists of the following basic components :

1. Back door outer panel ( upper)
2. Back door outer panel (lower)
3. Back door inner panel
4. Hinge reinforcements
5. Gas stay reinforcements
6. Latch and striker reinforcements
7. Wiper motor reinforcements
8. 

DESIGN CONSIDERATIONS :

• Functional requirements of hing and gas stay
• Rear visibility criteria
• Boot space
• Crash analysis
• Bend test , dent test , torsion test & endurance test
• Rear crash regulation
• Gap and flushness requirements

TOOLING DIRECTION TO BE CONSIDERED :

• Initially the tooling direction is created for deep drawing purpose before designing the inner panel
• Then styling surface is analyzed and irregularities are fixed
• Then backdoor was designed using the top down approach

LATCH AND STRIKER POSITIONING :

• For proper opening and closing of the back door , latch and and striker should be positioned at a correct position
• For measuring the correct position of the latch and striker hinge axis is taken the reference line and the circle is drawn by taking the hinge axis center point as the center of circle
• Now position the latch using above drawn circle which has to be perpendicular to the hood trajectory
• One positioned create a emboss on inner panel by extracting the face of the latch

BACK DOOR INNER PANEL

GAS STAY Reinforcement

1) We have to design the stay rod in such a way that it should not collide any another part , because of this collusion the rod produce the noise when the car in motion this causes the NVH ( NOISE , VIBRATION AND HARSHNESS)

2) Rod with the bends are more preferred because a straight rod will by wobbling , where as the same part with bent is rigid . these structured rod gives strength to the part.

WIPER MOTOR REINFORCEMENTS :

HINGE REINFORCEMENTS :

REDUCING THE NVH CAUSED BY BACK DOOR

Back door also causes the NVH in the car body , this can reduced by using the stiffener pad

STIFFENER PAD : These pad is introduced between the back door inner panel and outer panel to increase the strength locally . during the motion of the car the back door will wobble and causes the noise . To avoid these vibration and reduce NVH stiffener pad is introduced

HEMMING :

The process of creating a fold at the edge of the sheet metal to create a rounded safe edge is called hemming

There are four types of hems , they are

• Open hem
• Rolled hem
• Tear drop hem
• Closed hem

DRAFT ANALYSIS :

The Draft Analysis command enables you to detect if the part you drafted will be easily produced. 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.Minimum draft angle of 7⁰ is considered for analysis . green colour infer on the parts that all face along the tooling direction has positive draft angle greater than 7⁰ and passed in analysis

BackDoor Assembly Front View

BackDoor Assembly Rear View

CONCLUSION :

Hence the back door is designed with inner panel , outer panel, hinge reinforcements , gas stay reinforcements , latch and striker reinforcement & wiper motor reinforcements . Finally draft analysis are carried out to check feasibility of manufacturing.