Hood Design
HOOD INNER PANNEL DESIGN
DESIGN DATA OBTAINED TO DESIGN THE PANNEL:
- Outer Panel Thickness = 0.75mm
- Inner Panel Thickness = 0.75mm
MASTER SECTION PROVIDED TO DESIGN THE INNER PANEL:
Figure 1a
NOTE: MEASURED DIMENSIONS ARE IN MM
INTRODUCTION:
- The hood consists of outer and inner panels, with a striker assembly used to lock the hood.
- Hinge supports are present, which act as a pivot point to open and close the hood.
- Finally, a support rod is present to hold the hood in place when it is in the open position.
In some cars, to keep the hood opening hassle-free, they use gas stays to hold the hood in place. Slight force is required to open and close the same.
Refer to Figure 1b for details and representation of the hood's inner panel and outer panel
Figure 1b
HEMMING DETAILS ON THE OUTER PANEL:
Hemming is an operation of bending or rolling up of material edge to itself to join two materials
Hemming data-
1) Bend length = 6mm
2) Front Relief gap= 2mm
3) Gap between two materials =0.2mm (Top & Bottom)
Refer to Figure 1c for details and representation of the HEM
Figure 1c
HINGE AND STRIKER ASSEMBLY:
The hinge is the assembly that helps close and open the hood, which also controls how much the hood should remain open when it is lifted up.
Refer to Figure 1d for details and representation of the hinge and striker assembly
Figure 1d
Hinge and striker assembly is placed by the data, considering the average adult's height, such that it is easy for a person to work on the engine or other parts without the hood hitting the head of the person.
As you can see in the above figure, detail A & B gives us the dimensions of the hood in the open condition. Also, the striker mechanism is placed with respect to hinge data.
The angle of the hood at open condition = 49 degrees
Radius =315.5mm (center distance from striker to hinge axis)
MASTIC DATA:
Figure 1e
As you can see, the above figure (refer Figure 1d) shows the mastic sealants data, which has been used to hold the hood's outer panel to the hood's inner panel. The outer panel defines the aesthetic looks of the car. Hence should not be welded and only can be held by hems and sealant (silicon sealants).
The mastic points are placed on top of the embosses. Each mastic point has strength that can hold the outer panel by a dia of 80mm.
Note: For a sound structure of the inner panel, each mastic point has a holding dia of 80mm and has to overlap with the neighboring mastic point, or else the point/join becomes weak
In the figure, you can see mastic points and overlapped circles that depict the area of each mastic point holding strength.
The above design has equally distributed mastic data for good holding.
EMBOSS DATA:
Embossing is done to provide structural support for the mastic points and mainly for the hood's structural rigidity during a head-on collision. Embossing is done through dies and punches that need to be easily drawn.
The car manufacturers are keen on providing different designs of embosses that make the car more lightweight and provide good structural rigidity.
Refer to Figure 1e for details and representation of the emboss
Figure 1f
Emboss Specifications:
Emboss height = 10mm
Space between emboss and outer panel = 8mm
RELIEF DATA:
Relief is given to control the spring back of the material when the corners are rolled during the hemming process of the outer hood panel.
Reliefs are provided to the part or component to remove the stress in a particular area and are concentrated mainly in the sharp corners. Hence the corners are rounded or chamfered
- Figure 1f top panel relief
- Figure 1g bottom panel relief
Figure 1f
Figure 1g
DRAFT ANALYSIS:
Draft analysis is done to check whether the designed body can be drawn. The analysis is carried out on the tool called draft analysis on NX.
The coordinate system is created perpendicular to the latch and striker, and the draw direction is mentioned to check if the tool can punch in properly without messing up the work part.
Then the limit angle is mentioned, i.e., 5 degrees in this case. Then the part turns green if it can be drawn without any problem.
An indicator is shown on the side to indicate if the part can be produced. Refer: Figure 1h
Figure 1h
Green = >5 deg – 5 deg (can be drawn)
Yellow= 5 deg – 0 deg (can be drawn / sometimes not acceptable)
Blue = 0 deg - -5 deg (can be drawn only on special cases if the part is tiny and has to undergo special operation other than punching to obtain it)
Red = -5 deg - <-5 deg (cannot be drawn)
Figure 1i
Figure 1i shows the part is drawable and will not incur any problems.
Figure 1j
The above Figure 1j shows the drawability of embossed regions of the hood.
Figure 1k
The above figure shows the drawability of embossed regions of the latch and striker.
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