Design of backdoor

- Aim: To design the back door of an automobile using the styling surface along with necessary reinforcement and embosses.

- Method:

- Back door:

- A car door is a type of door, typically hinged, but sometimes attached by other mechanisms such as tracks, in front of an opening that is used for entering and exiting a vehicle. A vehicle door can be opened to provide access to the opening, or closed to secure it. These doors can be opened manually, or powered electronically. 

- The exterior side of the door is designed of steel or other material like the rest of the vehicle's exterior. In addition, its decorative appearance, typically coloured with a design, is intended to match with the rest of the vehicle's exterior, the central purpose being to add to the overall aesthetic appeal of the vehicle exterior.

- Design requirements:

- Hinge mounting:

- These are used in order to join or attach the door panel with the roof attachment in order to open and close the door properly.

- A door mounting method for an automobile, comprising: a door hinge-attaching step of preparing door hinges each comprised of a body-side hinge arm, a door-side hinge arm, and a hinge pin which connects said hinge arms to each other for rotation relative to each other, and attaching said body-side hinge arms to an uncoated automobile body, a temporary door-fixing step of temporarily fixing uncoated doors to said door-side hinge arms of said door hinges.

- Following images are showing the hinge parts which are used to attach the two components of the doors.

- Gas stay mounting:

- In order to attach the door and provide a provision to open and close it gas stays are used to provide an opening and closing mechanism. This helps in opening the door with minimum efforts.

- Different vehicle manufacturers prefer other ways to mount the door other than what is shown above, these kind of gas stay are mostly used in the rear door however some of these can be seen in the hood of premium cars.

- Latch mounting- in order to lock the door with the vehicle body and avoid any unnecessary opening of the door, a latch is provided to lock the door.

- Wiper motor:

- Windshield wipers are powered by a small electric motor, usually mounted on the firewall or under the cowl (the area under the windshield's base). The motor activates linkage that moves the wiper arms back and forth. On vehicles with a rear window wiper, a separate motor powers the one in the rear.

- Embossing:

- Sheet metal embossing is a stamping process for producing raised or sunken designs or relief in sheet metal. This process can be made by means of matched male and female roller dies, or by passing sheet or a strip of metal between rolls of the desired pattern. It is often combined with foil stamping to create a shiny, 3D effect.

- Embossed metals are used in industry for two reasons: (1) aesthetic, and (2) functional. Aesthetic applications also include appliance panels, building products, elevator panels, garage door panels, automotive trim, metal office furniture, and others.

- Functional applications are those in which a performance characteristic is enhanced. This can include a metal products ability to disperse liquid more effectively, reduction friction and static, increase a metal panel’s stiffness and rigidity, increase a metal surface area for acoustic or heat transfer applications, and improve traction.

-Draft analysis:

- Draft analysis is a means of understanding the feasbility of the part getting designed. This analysis shows is tha part is manufacturable?

- Basically draft analysis provide a basic understanding on the part, which areas are manufacturable and which are not.

- This is shown by the colour coding of the surface. In its simplest way, the areas which are appearing as green are manufacturable and the one in red and blue will create problems, becasue the blue areas are the one where the draft angle is negative and red area is the one where draft angle is zero.

- This is taken to the reference to the tooling axis of the component. Tooling axis is the axis along which the tool travels and the green areas are the one which clears the draft requirement and would not create any errors while manufacturing.

- Here a solution to the blue and red areas is to measure the angle and tilt the tooling axis in such a way that the angle at those regions comes to the minimum required draft angle.

- Hemming:

- Hemming is a process which is used to join the panels or surfaces without any joins or welding process. These are creating by bending the edges of the sheet.

- 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.

- Hemming reliefs are required to provide at certain places once hemming is done. These reliefs are provided in order to avoid any stress concentration as the surfaces are getting sudden change in area.

- Design procedure:

- In order to design the door panel, there are 3 things that need to be designed. 1st is an outer panel, 2nd is an inner panel and 3rd is a lower panel.

- The given input surface is having several free edges and all these needs to be properly joined and form as one single surface.

- Also many joined surfaces are having tangency issues that need to be removed. As these tangency issues can cause errors while thickening the surface, and also while offsetting.

- Following are the images that show the step by step procedure to show how to design the given door panel.

Tooling axis is need to be created, this axis defines the direction along which the tool travels to for the surface.	Some surfaces need to be improved as there might be some connectivity issues and proper tangency has to be done.
As it can be seen that the surface is having some tangency issues which need to be removed as this may cause errors while thickening the surface.
As the lower panel is not properly formed it is necessary to extract the separate surfaces and then a fillet is need to be provided.	In order to get the flange of the inner panel, the outer panel can be used. Here the surface has to be extracted and as per the design requirement the width has to be decided. In order to take the width border edge can be used to stpli the surface in particular width.
From the image, it can be seen that a smooth flange surface is formed and this can be used to form the inner panel area.	it is recommended to sweep the outer edge in small sections as a continuous one forming an error in thickening the surface.
After sweep and multi-section, a smoother surface is formed which the filleted and one inner flange can be formed.	Once the flange is formed, it is necessary to trim the flange with the outer and inner panels in order to form the edges and other flanges which can be later sweeped to create the surfaces.
Using the inner flange to trim with the outer panel.	As per the decided design, the corner edge is sweeped to formt he inner panel surface on which later the embossing can be done. This sweep angle must satidfy the draft requirements.
In order to form the surface, a proper fillet needs to be provided which form a smoother surface.	As the inner panel is constructed a little different instead of taking the sweep in an upward direction, a downward sweep is provided.
In order to join the surfaces a trin operation can be done, but to reduce the number of steps a direct fillet can be provided with desired fillet radius value.	From the surface, it can be seen that a smoother inner panel is created on which all the necessary emboss, hinge, gas stay, latch and cutouts as well.
Once the half panel is created before doing symmetry it is necessary to check any tangency errors are ther or not. Then it is also necessary to check whether the surface is getting thickned or not and then later it can be done symmetry.	Emboss is one of the required design parameters as these helps in improving the strength of the panel and diverting the forces are per the requirement. Here at the centre of the inner panel a emboss is created which is designed in suc a way that in case if there is a damage from the read side, this porsion is the one which comes in contact with the force and start absorbing the forces. This same purpose has ti be solved by other embossing which has to be done.
	Hinge mounting has been created, this is the mounting where the door connects with the roof or chassy area of the vehicle.
Mounting for gas stay has been created where the opening and closing mechanism of the vehicle is assembled. Here as per the requirement two holes are also needed in which the mounting mechanism can be fit into and along with this reinforcement is also required as this is the porsion where movements will be there and in order to aboid any wear and tear and provide more strength to this region, reinforcement need to be done.	In order to reduce the weight of the door small cuts outs are given, these cut-outs also help in force transmission and providing a better path to travel the forces where ever necessary.
Latch area is the one where, the door attaches with the body and gets locked to the car body.
Wiper motor area is need to be provided, where the wiper motor can be mounted with the proper assembly.	A complete panel is created with all the necessary mountings and emboss area.
Here while forming a surface a proper tangency has to be provided. This tangency results in forming a smooth surface which result in no error while thickening the surface.
Here while sweeping it is necessary to understand the angle which is provided here, must clear the draft angle requirement.	Draft analysis is needed to be done in order to see which areas can be manufactures and where need of improvement is needed.
Blue areas are where the surface is having a negative value and it would not be possible to manufacture the areas and further development is needed. Here it is necessary to remove this issue and in order to do so, it is necessary to measure the angle at that blue region and add the value to that angle which will result in a positive value. For this the additional angle is need to be added in tooling axis.	As this is a more complex area a seperate tooling axis can be used in order to manufacture this section.
	Wiper motor like these can be provided along with the mounting and such motors are mostly used.