Hood design-Week 2

Objectives:

*Design hood outer panel and inner panel and reinforcement with the given outer hood skin and master section design parameters

Introduction:

*The hood is the hinged cover the engine of the motor vehicles hood can open to allow access to the engine compartment for the maintenance and repair in the design perpesitive hood should meet some specific condtion like pedestrain safety,hood head zone ,for the lock striker,force distribution when the subjected to frontal collision ,manufacturing etc

*A typical hood assembly consist of the hood outer panel ,inner panel,latch and striker ,hinge .hood stay the hood stay is an appartus for supporting the engine hood of the moto vehicle in its open position the purpose of opening the engine hood is for inspecting engine room to change the cooling water and engine oil.changing the parts and making the repair etc the common type of hood stay are support rod and gas stay hood are typically made out of the same material as the rest of the bodywork this may include stell and aluminium deep drawing hemming blanking and pierecing are the common sheet metal operration that are used in manufacturing hood in automotive industries

1.Hood outer panel:

*Outer panel the aesthetic elements of the car it is styling team who provide the skin for the outer panel the shape position and size of the hood sholud satisfy the safety norms so while designing the hood we should give more importance to pedestrain safety the outer panel is attached to the inner panel hemming so it is necessary to provide required hemming flanging and relief for the hemming operation we also provide mastic sealents between outer panel and inner panel to reduce vibration

2.Hood inner panel:

*Inner panelis the part that gives strength and rigidity to the outer panel the master section represent the initial embos shape and strength the we provide the emboss for the latcj and hinge elements sfter fixing the location

3.Reinforcement:

*Reinforcement are provide according to the design mainly it provide at the hinge and latch region to improve the strength locally usually thickness of the reinforcement will be higher then that of the inner panel and the values according to cost and requiremnent here it given 1.5mm thickness to both hinge and latch reinforcements

4.Latch trajectory:

*Latch trajectroy is given by the from the hinge axis piont the hinge axis point is the centre point of the hinge axis we can fix the either latch or hinge if we fixed have the hinge position then we can should plot the trajectory for the latch for the proper mating condition of the striker axis through the tip of the striker should be tangentical to the latch trajecory

5.Emboss condition:

*Throughout the inner panel we provide different emboss we can increase the stifness of the inner panel through these emboss the shape and size of the emboss also determine the direction of the forces distribution resulted from the frontal collision the force should be always distributed away from the passenger in such a way that the force directed to either side of the car

6.Mastic data:

*Hood commonly posses large surface area and hemming can only be provide through it boundary we cannot use other joining techniques like welidng,riveting etc because they leave marks on the outer panel which spoil aesthetic appearance so mastic sealents are used to stick the inner surface and outer panel mastis sealents are elastic compound that behave like rubber it is applied between the inner and outer panels at specified spots each spot of mastic sealents has it effect around a circular region of 80mm diameter the mastic points are arranged is such way that it curves the aareas away from the hemming which are more vulcerable to vibrate..

7.Hamming:

*Hemming is a forming operation in which the edges of the sheet are folded over part in order to achieve a tight fit normally hemming operation are used to connect pars togeather to improve the appearance a part and reinforce part edges

*in car production ,hemming is used i assembly as a secondary operation after deep drawing trimming and flanging operation to join the two sheet metal parts outer panel and inner panel typical part of type of assembly are hood,doors,truck,and fenders

*they are two types of hemming operation:

1.conventional die hemming

2.roll hemming