Hood design-Week 2

DESIGNING OF HOOD ASSEMBLY

Objective

To understand and study the design methodology and mechanisms that goes under designing and developing an Automotiv
Hood to achieve maximum safety for everyone in and around vehicle.

HOOD DESIGN- CHALLANGE

Introduction:-

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 bonne
is made aerodynamic in order to minimize the air effect.

Hood design consideration:-

The hood of a car is considered as the frontal BIW enclosure component. Bonnets are designed to reduce air resistance as the a flows around the car. Apart from this, bonnets are also designed to meet several other requirements. They serve a great deal o purpose in protecting the passengers inside the car & the pedestrians in the event of an accident. It also acts as the cover for th engine.

• 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-mimic a collision at speed of 40 km/h.
• They describe a situation in which a 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 important criteria 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 direction
  through the embosses & directed towards the body of car. Thus protecting the occupants inside.

Following parts are using in hood assembly for this report,
1. Hood outer panel
2. Hood inner panel
3. Hinge assembly
4. Striker assembly

Hood thickness-
Outer panel thickness= 0.75 mm
Inner panel thickness= 0.75 mm
Reinforcement thickness= 1.5 mm

Inner Panel-

In the inner panel only we can research & implement the safety of pedestrians & as well as the driver. In this panel only we
can attach the reinforcement, embossed, mastic points etc.

It is an object of the present invention to provide a hood inner panel capable of reduction of a reaction force of the hood
inner panel even if a level of deformation of a hood of a vehicle increases, & 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 & inner panel ca
not join by any welding process like spot welding or rivet, which spoil the outer look of a car. The outer panel is generally extracte
model from the prototype design.

Hinge Assembly-
Hinge is a component that fixes the hood to the fenders of the car. The latch must be fixed perpendicular to the hinge axis so tha
the hood opens or closes properly.

Striker Assembly-
Latch & striker 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 doing the hemming process a relief angle is formed as a product of hemming when attaining at the corner of the sheet

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 t
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, producing a pattern or design on the sheet metal. Depending
on the roller dies used, different patterns can be produced on the sheet metal.

Latch trajectory-

While opening or closing the hood, the latch must be perfectly aligned to the fixing or striker point. For that, the latches trajector
must be perpendicular to the hinge axis.

Conclusion-

We have designed a hood that falls under the rules & regulations of the manufacturer's standards