Hood design-Week 2

HOOD DESING 

INTRODUCTION:-

Hood is main component of a car at the front portion.It help in protecting the engine sysytem and battery system by acting as shield.The shape of the bonnet is made aerodynamic in order to minimize the air effect.

• The European New Car Assessment Programme (Euro NCAP) is a European car safety performance assessment program which has developed test specifications & rating systems for assessing pedestrian injuries during impacts with the front of vehicles such test include a series of tests using impacts designed to bio-mimica collision at speed of 40 km/h.
• They describe a situation in whicha pedestrian is situated laterally & a car first hits one of his legs. Test are conducted on the leg, upper leg &most importantly the head, as head trauma is most commonly responsible for casualties.
• So to avoid severe injuries to the head, the high impact area for adults & children are subjected to less thickness. Also no reinforcement should be provided in that area as during head collision,the hood will absrob the head impact energy leading to collapse of the hood & thus protecting severe head injury.
• Another importantcriteria for the hood design is the protection of the occupants inside the car during front collision. The design of the hood should be in a such a way that the during the collision,the force should travel in the upward directionthrough the embosses & directed towards the body of car. Thus protecting the occupantsinside.

Followingparts are using in hood assembly for this report,

1. Hood outer panel

2. Hood inner panel

3. Hinge assembly

4.Strikerassembly

Hood thickness:-

Outer panel thicknes= 0.75 mm

Inner panei thickness=0.75 mm

Reinforcomentthickness= 15 mm

Inner Panel-

• In tho inner panol only we can research & implemont the safety of pedestrians& as well as the dirivor, In this ponol only wo can attach the reinforcement ombossod, mastic points etc.
• It is an objoct of tho presont invention to provicdo a hood innor panel capablo of rodiuctionof a roaction force of the hood inner panel even if a deformation of a hood of a vehicle increases and ensuring a sufficient energy absorption capacity.

OUTER PANEL:-

We can also call it as cover of inner panel. It is the part, which gives luxurious look to the hood or bonnet. Outer and inner panel can  not join by any welding proces like spot welding or rivet, which spoil the outer look of a car. The outer panel is generally extracted model from the prototype desing.

HINGE ASSEMBLY:-

Hinge is a component that fix the hood to the fender of the car. the lacth must be fixed perpendicular to the hinge axis so that the hood opens or closes properly.

STRIKER ASSEMBLY:-

Latch and stricker is used for locking the hood with the car. It is usually placed on the space provided on the inner panel.

The process involved in designing hood as a sheet metal operations is

• Blanking
• Hemming
• Punch cutting or piercing
• Deep drawing
• Embossing

Hemming

• Hemming is a sheet metal forming process in which sheets are joined by bending it usually to 180 degree. Automotive body panels & parts such as deck-lids, trunk- lids, doors, hoods & tailgates are formed by hemming processes.
• Roll hemming is carried out incrementally with a hemming roller. An industrial robot guides the hemming roller &forms the flange. Roll hemming operation can also be divided into several pre-hemming & final hemming process steps.
• Coventional 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 & trimming operations have been completed.

While doiing the hemming process a relief angle is formed as a product of hemming when attaining at the corner of the sheet.

Deep Drawing-

• Deep drowing 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 witha 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 passago, 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.

Embossing

• The sheet metal embossing operation is commonly accomplished with a combination of heat & pressure on the sheet metal, depending on what type of embossing is required.
• A sheet metal is drawn through the male & female roller dies, producinga pattern or design on the sheet metal Depending on the rollerdies used, different patterns can be produced on the sheet metal.

Latch trajectory-

While opening or closing the hood, the latch must be perfectly alinged to the fixing or stricking point. For that, the latches trajectory must be perpendicular to the hinge axis. 

HOOD ASSEMBLY OUTPUT:-

THE LINK FOR THE MODEL IS :-

https://drive.google.com/file/d/1b5YK1Xm-aNcdnlYZ0YKv5uXhTfakYHHe/view?usp=sharing