Design of backdoor of a LCV and determining latch trajectory using UG NX 10.0

Objective:

To design the inner panel and required reinforcements for mounting hinge and gasstay and wiper motor assembly for the given class A of the back door.

Introduction to back door:

• The backdoor is a door that gives access to the rear storage compartment of vehicles like trucks, vans, and SUVs.
• It is made from steel panels that open and close with the help of a hinge mechanism.
• The most common types of tailgates are drop-down, swing, split, and multi-way.
• The benefits of replacing a faulty tailgate include avoiding costly repairs, preventing rust and corrosion.

components and their characterstics:

1. Most of the steels used in automotive application are aluminium-killed steels of about 0.7 to 0.9 mm thickness.
2. For inner automotive parts, drawing quality steels, such as SPCD (JIS G 3141), A619 (ASTM), CR3 (BS1449), and Sr13 (DIN 1623), while for outer panels requiring deep drawing such as fenders, hoods, oil pans, etc. Non-aging extra deep drawing steels such as SPCEN (JIS G 3141), A620 (ASTM), CR1 (Bs 1449), and St 14 (DIN 1623), are used. Aluminium-killed steels show little or no stretcher strains for a period of time sufficient to eliminate the need for roller-leveling.
3. Thinner High Strength Low Alloy (HSLA) steels are being increasingly used for certain autobody components including skin panels.
4. It must combine its high strength with a good level of formability, as a strength increase is always accompanied by a fall in formability.
5. The improved bake hardening steels used specially for the external panels possesses sufficiently high formability and provides an increase in strength after the paint baking.
6. A consequence of strength increase obtained during paint baking, is the improved dent resistance of the surface.
7. Difficult autobody pressings of complex geometry have necessitated the use of steel grades with lower strengths too.
8. Vacuum degassed microalloyed steels containing Ti and/or Nb additions are classed as Interstitial-free steels (IF-steels).
9. IF-steels are being used with advantages of extremely high value of maximum drawing ratio, and the absence of the straining effect for difficult-to-form panels.

automotive stamping die

Procedure:

components of a car back door assembly:

• back door outer panel
• back door lower panel
• back door inner panel
• back door hinge reinforcemnt
• back door gastay reinforcement
• wiper motor reinforcement

correcting class A and determing tooling direction and latch and striker trajectory:

1. Open the given class A input
2. Try and join them if there are gaps create the surfaces locally using through curve mesh or studio surface and sew them
3. Create a tooling direction for deep drawing the back door ,generally the tooling direction is taken from the centre of the wiper motor area or it can draw from the x axis at an angle and can be modified when performing draft analysis

draw animaginary line from hinge axis to latch anf draw a circle and that faollows the latch and striker trajectory.

Creating inner panel of back door with flange and mastic flange

4. The back door sits on the flange provided to avoid water getting into the car and to reduce the NVH properties of the car
5. Offset the surface to 1.7mm where the position of the inner panel is determined and the flange must be 30mm from the outer panel
6. Offset the curve on face and trim the inner panel to get the flange and then using through curves create the surface between the flange and the inner panel
7. Likewise offset the lower panel to 60mm and then create a surface and trim them with the inner panel to get the inner panel with sealing flange
8. Create required embosses and make sure there are no sharp corners
9. To create flanges to apply mastic sealant offset the outer panel inwards upto 5mm and create swept surface between the inner panel and flange where mastics can be applied
10. Create one hole and slot for proper positioning
11. Crete embosses for hinge mounting and gasstay mounting
12. Create embosses for mounting wiper motor and latch using sketch and project curve
13. Trim he excess and create an extract body for thickening
14. Using thicken command thicken the inner panel inwards to 0.75mm

use sketch and project curve to project curves n the body and trim them to get the cutouts.

Creating outer panel hems

15. Double click on the outer panel upper to create hem to join with inner panel
16. Offset the inner panel to 2.65mm
17. Offset cur e on surface and trim the sheet up to 7mm
18. Use bridge curve and then using swept surface create the hem all along the surface if the outer panel
19. Do the same for the lower panel these two gets joined by spot welding with the inner panel
20. relief should be given at corners to reduce the stress concentration.

Creating reinforcements

20. Reinforcements are created from offseting the thicken part from the inner panel using wave geometry linker
21. Trim the reinforcements accordingly
22. Thicken the reinforcements to 1mm minimum to add extra strength locally.
23. Finally mirror the entire assembly

a hole and a slot for proper positioning of the wiper motor.

Draft analysis

24. Perform draft analysis selecting the tooling direction created before and give an angle of 7 degree .

concluion:

the tail gate of the inner panel is produced from the given class A input with proper opening angles for deep drawing and with proper reinforcemnts and embosses with dds extra strength to the body and draft analysis is performed with the drawing direction.