Hood design-Week 2

AIM

          In this project a Hood Assembly will be designed which would consist of hood outer panel, hood inner panel. The latch for the hood will also be placed at appropriate position considering that the hood should be opened and closed easily using its mechanism. The hinges will also be placed at appropriate position for the rotation of the hood inner panel.

INTRODUCTION

• A car hood is meant to protect the performance parts of your vehicle, including the engine, while also providing easy access for repairs and maintenance. It is possible for the hood to incur damage as well.    
• Hood is main component of a car at the front portion. It is used to decorate the car & add luxurious look. The shape of the bonnet is made aerodynamic in order to minimize the air effect.
• The hood of a car is considered as the frontal BIW enclosure component. Bonnets are designed to reduce air resistance as the air flows around the car. Apart from this, bonnets are also designed to meet several other requirements. They serve a great deal of purpose in protecting the passengers inside the car & the pedestrians in the event of an accident. It also acts as the cover for the engine.
• The hood is also prone to receiving scratches and dents. Although this might appear to be a minor problem, dents and scratches can lead to depreciation in the value of your vehicle. Scratches and dents can also lead to exposure to the elements that can result in rust and corrosion.
• This can be a serious problem that can ultimately expose the engine in your car to snow, sunlight, and rain. When this happens, it can impact the performance of your car's engine.
• The first important criteria for designing the hood is to set an opening angle till which the hood panel can be opened. This opening angle is different for different countries which largely depends on the average height of a person in that particular country.

     The movement of the hood can be controlled by either one of them:

     1. Gas stay

     2. Support rod

1.Gas stay

          A gas stay is a type of spring that, unlike a typical mechanical spring that relies on elastic deformation, uses compressed gas contained within an enclosed cylinder sealed by a sliding piston to pneumatically store potential energy and withstand external force applied parallel to the direction of the piston shaft.

2.supporting rod

          This is the most commonly used rod for opening and closing the hood at a certain angel. One end of the rod is hinged to the engine compartment and the other end is set free so that it can be locked to the hood inner panel when the hood is opened. This is usually used when the weight of the bonnet is small.

COMPONENTS USED IN HOOD

Latch Trajectory

          This is the part of the hood that has a trajectory or hook type design used to lock or unlock from the vehicle engine compartment.

Mastic data

          Mastic data is used for to reduce the weight of the inner panel and also to provide some space
in engine side.Providing mastic points for applying mastic which are rubber like material, which heated
spread evenly and help in reducing noise, vibration and harshness. 

Embossing

          Sheet metal embossing is a stamping process for producing raised or sunken designs or relief in sheet metal. Metal is drawn through the male and female roller dies, producing a pattern or design on the metal sheet.

Outer panel

          The outer panel is actually called thee skin of the vehicle which is designed by the styling team to get a good look for a vehicle by covering the inner panel and engine parts of the car. This should not be welded to the inner panel but using the sealant and matic data makes contact between the inner panel and outer panel which ac a bond between both and makes the hood stiff.

Inner panel

          The msin parts of the hood which giving support to the outer panel of the car and with its embossing shpes dessipate the forces in different direction when the vehicle takes crashes to not to injure the men in the car.

Data used:

Hood Thickness 

• Outer Panel Thickness = 0.75mm
• Inner Panel Thickness = 0.75mm
• Reinforcement Thickness = 1.5mm

DEEP DRAWING

          Deep drawing is a manufacturing process that is used extensively in the forming of sheet metal into a cup or box-like structures. Pots & pans for cooking, containers, sinks, automobile parts, such as panel & gas tanks, are among a few of the items manufactured by sheet metal deep drawing.

          A deep drawing of sheet metal is performed with a punch and die. The punch is the desired shape of the base of the part, once drawn. The die cavity matches the punch and is a little wider to allow for its passage, as well as clearance. For many calculations, the sheet metal thickness is assumed to remain constant. There are changes in thickness in certain areas, due to force involved.

          Whereas in pure deep drawing there is no reduction of sheet metal thickness, forming is achieved in stretch forming purely as a result of a decrease in sheet metal thickness. Stretch forming is extensively used for the forming of only slightly curved parts with low depth of draw (e.g. roofs, doors).

HEMMING PROCESS

          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.

          Conventional die hemming is suitable for mass production. In die hemming, the flange is folded over the entire length with a hemming tool. Normally the actual hemming is a result of a forming operation in which the flange is formed with a hemming tool after the drawing and trimming operations have been completed. The formed flange is then hemmed in several process steps. These steps include, for example, the pre-hemming and final hemming depending on the respective opening angle of the flange. Production plants for conventional die hemming are very expensive, but the cycle times are very low.

          Roll hemming is carried out incrementally with a hemming roller. An industrial robot guides the hemming roller and forms the flange. Roll hemming operation can also be divided into several pre-hemming and final hemming process steps. Roll hemming is very flexible to use and tool costs are significantly lower as compared to those of conventional die hemming. However, the cycle times are much higher since the hemming is realized using a hemming roller which follows a defined path.

TOP VIEW

FRONT VIEW

SIDE VIEW

ISOMETRIC VIEW

CONCLUSION

          Therefore we have desoigned a hood that falls under the regulation of the manufacturers standards.