Hood design-Week 2

what is the hood .

The hood is an opening boad panel that covers the engine vechile .the hood is also considered as another type of door in a vechile as it consists of an outer panel and inner panel the inner panel provides the strength while the outer panel functions as the metal cover.

hood stay .

a device for supporting the engine hood of another vechile in its open position.

purpose .

an automotive engine hood is arranged to be opened for the purposes of inspecting the engine and insplenshing cooling water and engine oil change parts making repair etc.

types of hood stay .

support rod .

• cost effective and simple .
• When striking with automoative body panel leave scars which are very likely to cause rust .

gas stay.

• No man power required .
• Cost of the part was high.
• A device for supporting the engine hood of a motor i its open position by menas of activator is activated gas.

Autombile head consists of the following components.

• hood innear panel .
• Head outer panel or skin of the hood .
• Reinforcment.
• Latch and striker assembly.
• Hinge assembley.

hood inner panel.

it is the skeltion of the hood it accomodates proper strength to components of the hood assembly based on functional requirements.

hood outer panel.

it is the outer most skin of the hood covers the automobile engine compartment and other components it echaces the overall look of the automobile and provides protection from external corrosive conditions.

reinforcement.

these add extra strength of the areas where attachments for the latch and striker assembly .hinge assembley etc.are provided in inner hood it minimizes the local stresses generated due to attachments.

latch and striker.

it is a locking mechanism of the hood attached to the inner panel and to the body of automobile.

hinge assembly.

it provides the rotatinal degree of freedom of the hood about in hinge axis in order to access the engine compartment of the automobile.

manufaturing methods for production of hood .

Hemming.

hemming is a forming process in which the sheets edges are folded over another section to create a shug fit.hemming procedures are commonly used for join the parts .improve the look of the part and reinforce part edges. in car part production hemming used to assembly as a secondary production for deep drawing,trimming and flanging operations to join two sheet metal parts outer and inner parts to gether parts for this type of assembly are hoods and doors trunk lids and fenders there are various types hemming operations .

• conventinal die hemming.

the flange is folded over the entire length with a hemming tool.

• rool hemming.

In rool hemming.the hemming is guided by an industrial robot to firm the flange .

deep drawing.

the deep drawing process is forming process which accurs under a combination of tensile and compresive conditions. A flat sheet metal blank is formed into a hollow body with small cross section in the automotive industry deep drawing is usually carried out using rigid tools when drawing complex car body parts in practice these are usually a combination of strech and deep drawing involved .

Edge cutting and hole punching .

the outer cover plate after strech forming and inner cover plate are placed respectively on corresponding trimming and piercing die,carry out trimming shaping, pierching and shapoing die draw accurate overal size blanking pressure gets 46KN to 68KN.

Deburring.

outer cover plate and inner cover plate are arranged on corresponding statinary fixture respectively uses sandee to get rid of the puching bore of outer cover plate inner cover plate .

Desgin consideration of hood .

safety from crash to the passengers .

during the crash of an automobile the hood should be cuumbled.so that it can be absorb the forces and directs the force distribution towards the hinges ribs are provided to the inner hood to stiffen hood .

pedestrain safety.

The distance between the ground and the evaluted areas of the cars i.e.wrap around distance wap is measured according to the length of the area when the pedestrain heads hits in accidents impact location are for children head is set based on the data of actual accidents in the crosswise diretion the side line of the impact test area is form line obtained by tracing the contact points between a straight edge and the side of the bonnet bomper at 45 degree.so proper dimensions are taken while designing the hood .

hinge .

hinge mounting surface should not have curvature it should be maintained as plane axis of rotation of both hinges should be same order to safety to functional requirements based on these conditions hood inner panel is desgined .

latch and strike assembly.

the point of intersection of strike and latch shud be hangentinal to the trajectory of the hood with respect to the axis of rotation of hood and this should be strictly maintained while designing the inner and hood striker mounting emboss.

mastic data .

The head inner panel and outer panel is joined to gether after the joining there will be a gap which leads to noise and vibrations in order to avoid that mastic seals are provided in between them improves NVH each mastic point has influenced of 80mm.

Allowances and Tolerances .

based on master sketch provided dimensions are taken accordingly for the desgin using emboss for manufacturing ponit of view in deep drawing a positive draft Angle should be provided in order to tool for retraction.reliets for the outer panel should be given proper allowances and Tolerances should be given.

conclusion.

it is a very important front compartment of cad body for the designing of the hood the parameters such as safety of the inside as ell as pedestrain.light weight with good force distribution must be considered the proper hood desgin was done using the nx cad by considering all the parameters .

THANK YOU.