Design of backdoor

                                                                                              REPORT OF BACK DOOR           

 Aim:

Using the provided styling surface to come up with a back door design and  using appropriate design methodologies and make the necessary reinforcements and embosses .

About back door :

 A door is one of the part in the vehicle, which is hinged or fixed to the vehicle body with open and close mechanism. Doors are used for entry and exit from the vehicle.

The back door is also swinging or closed commadity. Ans it is also known as Tail gate.

A car has 4 main doors which are hinged to both side of the car and one of the door is hinged in rear or back side of the car roof and  we call it BACK DOOR.

Back door is the type of door i car which is located in rear or back side of the car. This door is not use for entry and exit to the car. But this is used for close the back or rear side of the car and it also keep and protect  the some vechicle accessories of the car and limited luggages. This back door is hinged to the car roof  by hinges . Back door is provide the luggage compartment also.  The most of the car , the back door is operated manually and here gas stay are used to reduce the effort required to lift the door open. But some luxury cars have powered back door which is operated by electric motor.

The main purpose of the back door is avoid and protect the passenger from dust , rain and the other particles from the surrounding while car is moving and Even when stopped also.

 Types of the back door based on working positions

TOP MOUNTED:

   This type of  back door is at present  normaly use in all car's.           

 Today’s modern cars use   Top mounted back door which are operated by both powered and also gas stay . These top mounted doors provide greater rear visibility compared to side-mounted doors.

SIDE MOUNTED DOORS:

   Side mounted door , This door is hinged to the one side of the C-Piller of the car. This type door used in Van's , Trucks etc. This door is operated like a house door or window door's.    

    This door is provide the good luggage area also.

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.

And it is also give large luggage area. 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:

  A Gas stay types backdoor is most commonly used in all car's. This Gas stay mechanism is reduce the effort to open the door. The linear movement of the Gas stay is give the rotary motion to the Door hinges while Open and close the back door.    

       This Back door is  consist of a hinge, door, gas stay and some rubber beadings for sealing of door which is shown in the images below:

Powered 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.

Components of Back Door :

The Components of Back Door are mentioned below,

1. Inner Panel
2. Outer Panel
3. Hing Reinforcement
4. Latch and Stricker Reinforcement
5. Gas stay Reinforcement
6. Wiper motor Reinforcement

MANUFACTURING METHODS:

In automobile indusrty The BIW structure is  produced by Stamping process and Deep drawing process, and Sheet metal is used for overall body of the Vehicle.

What is Stamping Process?

Stamping — also called pressing — involves placing flat sheet metal, in either coil or blank form, into a stamping press. In the press, a tool and die surface form the metal into the desired shape. Punching, blanking, bending, coining, embossing, and flanging are all stamping techniques used to shape the metal.

Deep drawing :Deep-drawn automotive components possess a solid, durable wall surrounding their full diameter, which creates a seamless structure. This enables deep-drawn parts to be leak-resistant, waterproof, and airtight, making them more reliable under tough operational and environmental conditions.

BACK DOOR ASSEMBLY:

The back door assembly of a hatchback or SUVs has the following components.

• Inner panel
• Outer panel
• Hinge reinforcement
• Gas stay reinforcement
• Wiper motor reinforcement
• Latch/striker reinforcement

Design Consideration :

• Visibility Criteria
• Manufacturing feasability
• Latch and Stricker Position
• Open & Close criteria
• Hing Position 
• Gas Stay Position
• Space Avalibility
• Drain Holes
• Hemming and Relief area's
• Joining Technic
• Sealing method
• Good space for luggage
• Rear Crash test
• Sealing Flange clearence

INNER PANEL:

    Inner panel is  a component of the back door, Which is used for strengthening the door asssembly , and it is most important component on which all accessories are mounted like Hinges , Gas stay reinforcement , Wind sheild glass mounting channel, Latch etc. The wind sheild glass has it's own gradient line for visibility criteria. 

The possible method is the integration method. In the integration method, the part is stamped out of a single blank. This reduces the number of tools needed; the assembly cost and eliminates any fit ability problem. In inner panel needed embosses are created for to improve the strength of the inner panel. 

And here we have to give the space for  tail lamp, rear fog lamps.

 Emboss:   Embosses are give the more strength to the part, and Y-Emboss &  V- Embosses are give the more strenght.

OUTER PANEL :

   The Outer panel of the back door is similar to the BIW component of the vehicle. The outer panel also has the space  for the tail lamp, rear fog lamp and also has the provision for licence plate mountings. Most of the hatchback cars have the provision for wiper motor. This  Outer panel is produced by stamping process and it is assemble with the inner panel through hemming process.

DRAFT ANALYSIS FOR BACK DOOR : 

 This is most important process for all components, Because we are produce the component in Stamping process . In this process the sheet is will be press between the Punch and Die. In this process the final product should  be easily remove from the Die, so here we have to maitain the Min 7 Degree  draft angle.

So before the production we should analyse the draft angle , here we use Draft Analysis command for check the draft angle.

Here Some Colours are showing. Each colours are represent is draft angle of the component .

The Green colour is represent possitive draft angle ,

The Yellow colour is represent the draft angle which is below 7° & above 5°.

The Blue colour is represent the draft angle which is in between 0° to 5° .

The red colour is represent the draft angle which is negetive draft . is -5° to -7°.

DESIGNING THE REINFORCEMENTS:

                        Here we maitain the Thickness  for all reinforcements is 1.5 mm

Reinforcements are give the support and strenght to the hinged point , gas stay and latch-striker point of the doors, it will produced  from scrap or unwanted sheet of the door .when the stamping opertaion is done the scrap material is separated from the door and that scarp metal is going to produce the required shape of reinforcement as show in the below image. This is reduce the production cost of the component.

      REINFORCEMENTS  :  The reinforcement provided is of 4 numbers which consist of :

1. HINGE REINFORCEMENT (Left & Right)
2. GAS STAY REINFORCEMENT (Left & Right)
3. WIPER MOTOR REINFORCEMENT 
4. LATCH REINFORCEMENT

            Here all Reinforcements were created in NX CAD by using the same method.

Initially the linked body was created separately for each with the help of extract geometry and the required portion was trimmedout then thickened to 1.5 mm.      

 1.Hinge reinforcement :

             Hinges enable the opening and closing of the back door. 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. and its allowing only a limited angle of rotation between them.

             The hinge reinforcements are added to compensate for the weak region due to the acting load over it.

Embosses :  Embosses were creating For every Reinforceent. This embosses will increase the strenght of the pannel, reduce the weight  and  embosses are provide the flat area to assemble the all reinforcements.

2. Gas Stay Reinforcement:

Gas stay is a device used for supporting the back door when its open condition and also reduce the effort to open the door. Gas stay is not requires manpower , when the door is opening. And Gas stay has two end one end is fixed to the car body & another end is fixed to inner panel of the back door as shown in the fig.

But before that we have to provide the Reinforcement to the gas stay then gas stay willbe fix on it, this Gas stay Reinforcement is will give the streght to the weak region and give support to Gas stay for fix with the back door.

The distance b/w the hinge Axis to Gastay Point is can't be more than 90 mm & can't be less than 60 mm. & angle also  should be 80°-90°. In this case door opening OR  rotation of the door is Smooth.

If The distance b/w Gas stay and Hinge Axis is less Than 60 mm or more than 90 mm the kinematic is not work. And this value is not same for the all Car's, It's depend upon the type of Gas Stay & type of kinematic follow & wieght of the door.

The Hinge Axis , Latch striker & Gas stay all are Co-related each other. It can't be changed , If we changed we have to modifie the Latch & Sticker point And Gas stay also.

   Embosses   :  Embossing is provided at the Gas Stay mounting area  to compensate for weakness and improve strength.

 This embosses are created in both C- Pillers also.

3. Wiper Motor Reinforcement:

                Wiper motor reinforcement is created to mount the wiper motor assembly.

4.Latch and Striker Reinforcement:

               The Latch & Striker forms 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.

Sealing Flange Cleaarence :  This the gap between two mating faces one is Back door Flange which in Inner panel & one is gasket which is insert on the gasket gradient line. When we close the door in that time gasket will compress or   squeez between the door flange & cover the entire area. when the door is open this gasket will returns its original shape.

So here we shoukd maintain the min clearence for sealing flange .

Inthis case i maintain the 25mm clerence for sealinge flange

What is Gasket:   

 JOINING METHODS:

1.SPOT WELD : Spot welding (also known as resistance spot welding) is a resistance welding process. This welding process is used primarily for welding two or more metal sheets together by applying pressure and heat from an electric current to the weld area.

For achive the Spot weld need min 10mm gap b/w 2 surfaces.

2. HEMMING OPERATION:

            Hemming is a sheet metal forming process in which sheets are joined by bending it to 180 ,

OR  Hemming is a mechanical joint design which is used for joining inner and outer closure panels as found indoors, hoods, bonnets and lift gates. To increase crash resistance the gap between the hemmed panels is filled with a high-strength adhesive which also prevents from corrosion.

Corner Relief:

Relief helps to control sheet metal material behavior and to prevent unwanted deformation during unbend operations. So here we have to provide cornor relief for Back door.

Latch/striker rotation angle or Tregectory of Back door :

           This is one of the most important point  to produce the back door and any door of the vehicle, also This rotation angle of the line denotes the line of action of backdoor when hinged to the body of the car. This rotation angle is show the where we have to create the embooss for latch and striker for perfect closing locking of the door.

LOAD TEST -General Analysis :

After produce the Back Door we should conduct the some Test for the Back door to check the quality of the door.

Here i mentoined type of Test what we should conduct.

• Bend Test
• Torsion Test 
• Abuse Test
• Dent Test
• Assembly load cases
• Endurance Test

Type of Metal Used to Back Door: 

Most of the cars back door is made from Sheet Metal (Steel) , But some of the Car's which are top end Car's they are all use Aluminium for produce the back door.

The reason is Aluminium is light weight compare to (Steel) Sheet metal , but cost is more than sheet metal.

But now a days everyoune using Alluminium Parts.

 The difference B/W Aluminium & Steel :

                      ALLUMINIUM                                                                     STEEL

1. Parts are casted , Reinforcement can be neglated.                    1.Parts are stamped     
2. Local thickness can be varied.                                                 2.Reinforcement are necessary
3. Lighten in weight.                                                                  3. Has only Uniform Thickness
4. Less Number of components.                                                  4.Heavier in weight & more number of components
5. Casting Draft angle is min 3°.                                                 5. Draft angle in Stamping is 7°.
6. Less density                                                                          6.High density
7. Less Radius we can.                                                               7. Should be maintain 3mm radius in bending

FRONT VIEW

BACKSIDE VIEW 

SIDE VIEW

ISOMERTIC VIEW

Conclusion:

Thus the design of BIW Fixtures of a Backdoor of a car has been designed using NX-CAD (Student Version).

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