Hood design-Week 2

Aim: To design car hood in NX using given master section and the specified design parameters.

Introduction to Hood:

Car hood/bonnet is a hinged cover that rests over the engine in a front-engine car. Hood can open to allow access to the engine compartment for maintenance and repair. Hood is also considered as another door as it consists of the outer panel and an inner panel like side doors of a vehicle.

The following are the components of Hood:

1. Hood Outer Panel

The outer panel is a metal cover which provides aesthetics look to the vehicle.

2. Inner Panel

The inner panel provides strength and supports the outer panel. It also directs the force of the collision outwards instead into the engine compartment of the car.

3. Hinge

Hinge allow the hood to rotate around a fixed axis for opening and closing movement.

4. Striker

It is U shaped bend that attaches to the latch in order to lock the hood and prevent any loose movement during the car motion.

5. Support Rod

It is a device that supports the hood in open position

Design Methodology for Hood:

• First the inner panel is designed from the given master section using the various commands and features. We create the embossing using the offset surface from the original master section. Similarly, we create the cuts on the emboss by sketching and using trim surface option.
• Then the outer panel is designed from the same master section. Here we are supposed to provide the hemming to outer panel. The parameters of hemming are taken as per given values.
• Now, on the inner panel, the embossing for hinge and striker are produced by considering their respective dimensions and assembly positions. First the emboss for hinge is created and then by fixing the hinge into its position, we draw an axis passing through both side hinge axes to form a common axis. And then we position the striker such that it will move along circumference of a circle whose centre is at midpoint of the common axis. Thus, position of striker is decided and we can create emboss for the same.
• Using the hinge emboss we created, we can create our hinge reinforcements by creating new parts in the assembly itself.

Sheetmetal Operations in Car Hood Manufacturing Process:

1. Deep Drawing:

It is a sheet metal forming process in which a sheet metal blank is radially drawn into a forming die by the mechanical action of a punch. The process is considered deep drawing when the depth of the drawn part exceeds its diameter.

2. Hemming:

Hemming is a forming operation in which the edges of the sheet are folded over other part or simply folded in order to achieve a tight fit. 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.

3. Embossing:

Sheet metal embossing is a stamping process for producing raised or sunken designs or relief in sheet metal. This process is carried out by means of matched male and female roller dies, or by passing the sheet or rolls of metal between rolls of desired pattern

4. Piercing:

It is a shearing process in which raw sheet metal is pierced with a machining tool, resulting in the creation in a particular shape hole in the sheet. The major difference between blanking and piercing is that in blanking the cut out is the workpiece and outer part is scrap, while in piercing, the cut out is scrap and the outer sheet is the workpiece.