Design of backdoor
BACK DOOR DESIGN
Aim :
Use the provided styling surface to come up with a back door design, use appropriate design methodologies, and provide the necessary reinforcements and embosses.
Introduction :
An automobile back door or Tailgate is the panel that covers the boot (or trunk) of an automobile. It enables access to the main luggage compartment. A hinge allows the boot lid to be raised, while devices such as springs or gas cylinders hold it up in the open position The Backdoor is an assembly of many parts such as inner panel, outer panel upper, outer panel lower and Reinforcement. Inner panel is attached to the outer panel using mastic sealant.
The truck or boot of a car is the vehicle's main storage or cargo compartment, often a hatch at the rear of the v vehicle. it is also called a tailgate. In India, the storage area is known as a dickey and in south Asia as a compartment.
The trunk or luggage compartment is most often at the rear of the vehicle. Early designs had an exterior rack on the rear of the vehicle to attach the luggage trunk. Later designs integrated the storage area into the vehicle's body and eventually became more streamlined. The main storage compartment is normally provided at the end of the vehicle opposite to which the engine is located.
If the door is hinged at the bottom it is called a tailgate, particularly in the United States. They are used on station wagons and pickup trucks, as well as on some sport utility vehicles (SUVs). Traditional drop-down station wagons and pickup tailgates can also serve as a mount for a workbench.
Traditional U.S. station wagons included a roll down window retracting into the tailgate to load small items or to allow the tailgate to be opened down on its bottom-mounted hinges. Because of the potential for carbon-monoxide fumes, the tailgate window on station wagons should be closed whenever the engine is running.
Two-way station wagon tailgates may be hinged at the side and the bottom so they can be opened sideways like a regular door, or drop downwards as load platform extenders. They are designed with special handle(s) for opening in the selected direction on special hinges after the window is lowered.
A three-way design that was also used by Ford allows for the tailgate to be opened like a door with the window up. General Motors developed a clamshell-style "disappearing" design where the rear window rolls up into the roof and the tailgate slides down and beneath the load floor. If the door is hinged at the top it is termed a hatch and is used on a hatchback. A bottom opening door is now common on SUVs.
Design Considerations :
- The windscreen should give good visibility.
- The door should be strong to sustain the impact during a collision.
- The door should be thin to maximize the boot area.
- Door should be light Weight for opening manually.
- Some of the load cases are Bend test, Dent test, Torsion test and Endurance test.
Design Methodology :
Various no of Part present in the Back Door are as follows,
- Back door outer panel (upper)
- Back door outer panel (lower)
- Back door inner panel
- Hinge reinforcements
- Gas stay reinforcements
- Latch and striker reinforcements
- Wiper motor reinforcements
Back door outer panel :
The Outer panel of the back door is similar to other BIW components where it is the aesthetic part of a vehicle. the outer panel also has the provision for the tail lamp, rear fog lamp, wiper motor and also has the provision for licence plate mountings.
Back door inner panel :
The Inner panel is a component that is used for strengthening the door and it is one of the most important components on which all accessories are mounted like hinges, glass guide channel, mounted trim, latch etc. the possible method is 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.
Hinge reinforcements :
Hinges Support the weight of the whole backdoor. Emboss is designed such that the hinges should be operated freely. The electrical Wiring looms are through the holes along the peripheral to keep them hidden.
Gas stay reinforcements :
An angle or diabolic emboss is provided for the gas stay mounts. the angle makes it easy to be machine and stamped it is reinforcement with a thicker sheet.
Latch and striker reinforcements :
At the bottom of the latch and assembly generally, a key-operated or automatic remotely controllable locking mechanism is used to keep the door closed and open.
Wiper motor reinforcements :
A cavity is placed in the middle of the panel for necessary components in the assembly as well as other accessories. The holes or cavities are placed strategically to accommodate wiring looms, tail lamp mounts, and other accessories. embosses help stiffen the panel and act like local reinforcements. extension are provided around holes that are attached to outer panels and acts are crumple zone elements in case of rear impacts.
Design Process :
Checking the geometry :
The styling surface is the surface which is provided as input in order to design the back door.
Try joining the upper surface. If the surface is sew together, that is the outer surface or working surface.If not the need to create the surface by using studio surface tool. Create a fillet areas, tail lamps areas as those area will be unable to join.
Tooling axis :
The tooling axis plays important role while making the component.Its the axis of line along which the componet will be extracted after the component is been moulded
Draw a line from left and right almost parallel to the path of the surface along the unsymmetrical axis. Using the derived line tool, Create a bsecting line.
Emboss :
The metal sheet embossing operation is commonly accomplished with a combination of heat and pressure on the sheet metal, depending on what type of embossing is required. Theoretically, with any of these procedures, the metal thickness is changed in its composition.
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. The pressure and a combination of heat actually "irons" while raising the level of the image higher than the substrate to make it smooth. The term "impressing" refers to an image lowered into the surface of a material, in distinction to an image raised out of the surface of a material.
In most of the pressure embossing operation machines, the upper roll blocks are stationary, while the bottom roll blocks are movable. The pressure with which the bottom roll is raised is referred to as the tonnage capacity.
As the back door opens and closes in the upward and downword direction, during the time force is generated on it which is might effect the durability.
Sheet metal embosing is the stamping process for producing raised relief in sheet metal. Embossing is done by pressing the sheet metal.
EMBOSS WORKS ONLY FOR SHEET (SURFACE MODELLING)
STEP 1: create your sheet feature.
STEP 2: create a plane offset at a distance
STEP 3: create a sketch on the plane to be embossed
STEP 4: select emboss, and select your face and sketch.
STEP 5: Emboss created
Mastic Points :
Mastic sealent is used on the surface to connect the inner and outer panel with the gap of 5mm.
In oder to fix the outer pannel to inner pannel a masric extension flange is created. So offset the outer surface 5mm downward and create a plate from the inner panel.
In oder to improve the strength to the inner panel various embosses are designed on it to fix the reinforcement.
Hinge emboss:
Hinge emboss will placed in the top side of the inner panel in the left and right side.
Gas stay :
Gas stay is the component which is used to lift the back door with help of pressure a button.
There are 2 types of Gas stay
- Manual system
- Automatic system
Latch emboss:
Latch emboss is designed at the bottom portion of the back door. This door is used for locking the back door of the car.
Wiper motor Emboss :
Wiper motor Emboss is the designed at the middle of the back door wher the wiper motor will be placed on the back door.
Reinforcements :
Reinforcement are the component which are used to add strength at particular region.
The reinforcement designed for the back door are,
- Hinge Reinforcement
- Gas stay Reinforcement
- Latch Reinforcement
- wiper motor Reinforcement
Hemming :
Hemming is metalworking processes in which a sheet metal edge is rolled over onto itself. Hemming is the process in which the edge is rolled flush to itself, while a seam joins the edges of two materials.
The process for both hemming and seaming are the same, except that the tonnage requirement is greater for seaming. The process starts by bending the edge to an acute angle. A flattening die is then used to flatten the hem
Hemming is a sheet metal forming process in which sheets are joined by bending it usually to 180°. Automotive body panels and automotive parts such as deck-lids, trunk-lids, doors, hoods and tailgates are formed by hemming process. This paper present a systematic review of sheet metal hemming process based on materials used in hemming process.
Corner Relief :
Relief is done to decrease the stress concentration along the corners and also to decrease the clumping of metal along the corners, this is done by trimming the corner by a minimum radius for the rollers to pass along smoothly.
Corner relief are also provided at the corners so that the hemming can be easily performed in all the regions.
Draft Analysis :
Draft angles are very important in thermoforming product design. If the product is formed onto a female or negative mold, it shrinks away from the mold sidewalls. As a result, true female or negative products can be thermoformed with vertical walls having zero draft angles.
The Draft analysis is performed go check whether part satisfies for manufacturing process on basis of the tooling direction created initially.
The draft analysis command enables us to defect that the part drafted will be easily removed or not. this type of analysis is performed based on color ranges identifying zones on the analyzed element.
Backdoor Assembly Topside View :
Backdoor Assembly Backside View :
Conclusion :
Here, the parts of the back door were designed using the top-down approach in NX Cad. All the required reinforcements were designed and assembled.
Thus the back door was designed from the given styling surface and Draft analysis is also done on the inner panel to check the manufacturing conditions. In this challenge i learned to design the Inner panel, the Outer panel, Wiper Motor reinforcement, Hinge reinforcement, Gas Gtay reinforcements, Latch and Striker reinforcement and its position.