Design of backdoor

Design of Backdoor

Aim: To design various components of back door with help of reference data given and validate them with preset criteria.

Back door:

A back door is a type of door opening, typically hinged on its front edge, but sometimes attached by other mechanisms such as tracks.

It may be manually operated or with power assist supplied by the vehicle. Powered doors or power doors may be found on minivans, luxury vehicles, or modified cars.

Types of back door are given below:

Based on mounting method

• Top-mounted
• Side mounted doors
• Bottom / split type

Based on working mechanism

• Gas stays type
• Powered lift system

Mounting type of back door:

Top mounted door:

This type of back doors is used in a station wagon, pickup truck and some of the sport utility vehicles.

• Modern cars use top-mounted tailgating systems which are both powered and also gas stay supported.
• These top mounted tailgates provide greater rear visibility compared to side-mounted or bar doors which have canter pillars in it.

                                                                                                                             

Side mounted doors

Side-mounted doors are the one which is used in the van type MPVs, SUVs, pickup truck vehicles. These side-mounted doors or barn doors are a lot easier compared to top-mounted doors.

These doors are generally smaller in size and can be easily accessed. These doors are more convenient for the goods handlers for long pipe and lengthy components where one door is kept open. These doors also save accidental head impacts. It is a lot easier to load and unload items in the side-mounted doors.

                                                                                                                                       

Bottom / split type

This bottom type or split type backdoor system are used in the car type such as estate type car, pickup trucks and some luxury SUVs.

These are the most convenient type of back door in which the bottom split is used as a support or even as a table for the tour going people.

                                                                                                                                

Types based on working mechanism.

Gas stays type:

            Gas stay types backdoor/lift gate/tailgate is an ideal and most commonly used tailgate mechanism from lower segment car to luxury car segment. The ideal components of tailgate consist of a hinge, door, gas stay and some rubber beadings for sealing of door which is shown in the image below:

Power door:

Power trunk lid system is another sophisticated way of trunk/liftgate opening mechanism which is to automatically open and close of the trunk/liftgate and release of the latch by the touch of a button. The following image shows the component as used in the powered trunk/back door lift system.

Powered trunk lift system consists of a power latch, anti-pinch switch, PTG ass’y, PTG main switch. When the switch is pressed in the compartment or outside the power latch releases the latch and the entire backdoor is opened. The anti-pinch switch is located in order to avoid accidental hand insertion during the operation of the door.

                                                                   

Different Sheetmetal processes used for manufacturing the Back Door

Embossing:

Embossing is a metal forming process for producing raised or sunken designs or relief in sheet materials by means of matched male and female roller dies, theoretically with no change in metal thickness or by-passing sheet or a strip of metal between rolls of the desired pattern. 

Metal sheet is drawn through the male and female roller dies producing a pattern or design on the metal sheet. Depending on the roller dies used, different patterns can be produced on the metal sheet.

Materials commonly used in the metal embossing process include:

Aluminum alloys

Steel alloys

Zinc

Copper

Galvanized steel

Brass

Cold rolled steel

Hemming:

Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to achieve a tight fit. Normally hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges.

In car part production, hemming is used in assembly as a secondary operation after deep drawing, trimming and flanging operations to join two sheet metal parts (outer and inner) together. Typical parts for this type of assembly are hoods, doors, trunk lids and fenders.

There are various types of hemming operations:

Conventional die hemming: In conventional die hemming, the flange is folded over the entire length with a hemming tool.

Roll hemming: In roll hemming, the hemming roller is guided by an industrial robot to form the flange.

Open Hem: A Hem has a full round feature and a return flange. In open hem bend angle is equal to 180 degrees.

Tear drop Hem: In tear drop hem the bend angle is greater than 180 degrees.

Closed Hem: Hems without any inside radius are called as closed hem. Closed hems are not recommended if the hem geometry is to be painted or if the material used is SST or Aluminium.

Blanking:

Blanking is a cutting operation of a flat metal sheet and the article punched out is known as blank. Blank is the required product of the operation and the metal left behind is considered as a waste.

Punching:

It is similar to blanking only the main difference is that, the hole is the required product and the material punched out from the hole is considered as a waste.

SPOT WELDING:

Spot Welding is a form of resistance welding also known as Resistance Spot Welding (RSW). Spot Welding involves using heat produced by resistance to an electrical current to join materials together. The current heats the materials to a point where they become malleable. The use of strong pressure bonds them together.

Masting:

An adhesive sealent is used to join two surface where appearance plays major role. Apart from that it is also used to join two surfaces where welding is not possible.

Back door:

 It consists of 4 given parts below:

Outer upper panel

Outer inner panel

Inner flange

Mounting reinforcement

Outer upper and lower panel

It is the main body that can be seen looking at the back door.

It provides aesthetic look and provides enclose for various mountings.

Snapshots of outer panel are given below:

Inner sealing flange

An inner panel provides reinforcement and sealing from environment.

By providing embosses and cut outs  strength of back door is increased.

Mounting reinforcement

Reinforcement are given in inner panel to provide extra strength and reduce stress concentration in those areas where forces are applied while operating back door.

Various mounting reinforcements images given below:

Draft analysis of inner panel:

 

Images of assembly:

 

Masting to join inner and outer panel.

Corner Relief: