Challenge

Hood design-Week 2

Design Hood outer panel, inner panel and the necessary reinforcements by following the Master section mentioned with the design parameter explained in the videos. Submit an assembly of Hood inner panel, outer panel, latch, hinge and the reinforcements

A detailed report about the Hood Design which includes a detailed explanation about hood and its components, Latch trajectory, Mastic data, Emboss definitions, manufacturing process like deep drawing and hemming, and all the parameters followed in the design.

The report should be well-formatted and should have a good flow of content. Add all the relevant images

Data to be used:

Hood Thickness Information

  • Outer Panel Thickness = 0.75mm
  • Inner Panel Thickness = 0.75mm
  • Reinforcement Thickness = 1.5mm

Master sketch:

Short Intro for hood

The hood (American English) or bonnet (Commonwealth English) is the hinged cover over the engine of motor vehicles. Hoods can open to allow access to the engine compartment, or trunk (boot in Commonwealth English) on rear-engine and some mid-engine vehicles) for maintenance and repair.

DESIGN CONSIDERATIONS

pedestrian rating

force distribution

ensuring DFM (sheet metal process)

hood standards

pedestrian rating

the most important thing is a safety regardless of anything. so there are times that pedestrians will be hit by the hood of a car. while the head is laid on the hood that specific portion should absorb the energy instead of resisting. to prevent causes. the hitting zone will be different because of so many factors like ages, country, etc.

force distribution

when the force is acting on the center of the hood. the force should be spread like a wave instead of a single direction. it will drastically reduce the impact on the passengers. by adding emboss we can achieve this

Components

1.Hood outer panel

The outer panels are the aerodynamic and aesthetic for the car. The Hood is one of the parts that gives look to the car. It is the styling component that provides the skin for the outer panel. The shape, position, thickness and size of the hood should satisfy the safety norms. Designing the hood is one of the most complicated to create because it not only look is also give more importance to the pedestrian safety. Concept of the hood outer panel is to attach to the inner panel by hemming. It is necessary to provide required hemming and all necessary need to create this hood. We also give some amount of plastic or rubber to contact both to geather.

2.Hood inner panel

Inner panel is the part that gives strength and structural rigidity to the outer panel also known as the skin. In the important panel with the design of embossing and shape and size. In this panel we need to create the emboss for latch and hinge elements after fixing the specified location.

3.Reinforcement

Improving Performance or Stiffness of the Car Body

This way sheet metal thickness will be reduced and steel reinforcement plates are unnecessary. It is a contribution to reduce the weight of vehicle and may also avoid creation of vibrations and thus noise and fatigue cracks in the structure.

Reinforcements are provided according to the design requirements. Mainly it is provided at the hinge and latch regions to improve the strength locally. Usually thickness of reinforcements will be higher than that of the inner panels and the value varies according to cost and requirement. According to the design requirement here it is given 1.5mm thickness to both hinge and latch reinforcements.

4.Embossing process

Sheet metal embossing is a stamping process for producing raised or sunken designs or relief in sheet metal. This process can be made by means of matched male and female roller dies, or by passing sheet or a strip of metal between rolls of the desired pattern. It is often combined with foil stamping to create a shiny, 3D effect.

The metal sheet embossing operation is commonly accomplished with a combination of heat and pressure on the sheet metal, depending on what type of embossing is required. Theoretically, with any of these procedures, the metal thickness is changed in its composition.

The metal sheet embossing operation is commonly accomplished with a combination of heat and pressure on the sheet metal, depending on what type of embossing is required. Theoretically, with any of these procedures, the metal thickness is changed in its composition.

Metal sheet is drawn through the male and female roller dies, producing a pattern or design on the metal sheet. Depending on the roller dies used, different patterns can be produced on the metal sheet. The pressure and a combination of heat actually "irons" while raising the level of the image higher than the substrate to make it smooth. The term "impressing" refers to an image lowered into the surface of a material, in distinction to an image raised out of the surface of a material.

In most of the pressure embossing operation machines, the upper roll blocks are stationary, while the bottom roll blocks are movable. The pressure with which the bottom roll is raised is referred to as the tonnage capacity.

Embossing machines are generally sized to give 2 inches (5 cm) of strip clearance on each side of an engraved embossing roll. Many embossing machines are custom-manufactured, so there are no industry-standard widths. It is not uncommon to find embossing machines in operation producing patterns less than 6 inches (15 cm) wide all the way up to machines producing patterns 70 inches (180 cm) wide or more.

latch trajectory

the hinges should be placed in this way. which is the two hinge axis will share the same axis. from the center of the axis, if we draw a circle from the center of two henge axis to the striker lock point. center of striker lock point should be perpendicular to the hinge axis. so the hood will be open and close perfectly.

Deep Drawing

Deep drawing is one of the most widely used processes in sheet metal forming. Apart from its use in many other sectors, it is applied in the automotive industry for the manufacturing of car body parts.

Process definition:

The deep drawing process is a forming process which occurs under a combination of tensile and compressive conditions. A flat sheet metal blank is formed into a hollow body open on one side or a hollow body is formed into a hollow body with a smaller cross-section.

Deep drawing processes are divided into three types:

  • Deep drawing with tools
  • Deep drawing with active means
  • Deep drawing with active energy

In the automotive industry, deep drawing is usually carried out using rigid tools.

The figure illustrates the deep drawing process. The rigid tools consist of a punch, die and binder. In deep drawing, the plate holder closes after the metal sheet blank has been inserted.

Next the sheet is clamped between the die and the binder. This process slows down the flow of the sheet while it is being drawn and thereby prevents wrinkles from forming under the binder. The punch stretches the sheet over the die radius and forms it in the die. The amount of punch force necessary for forming is thereby continually increased up to the lower dead center of the punch.

Whereas in pure deep drawing there is no reduction of sheet metal thickness, forming is achieved in stretch forming purely as a result of a decrease in sheet metal thickness. Stretch forming is extensively used for the forming of only slightly curved parts with low depth of draw (e.g. roofs, doors).

When drawing complex car body parts in practice, there is usually a combination of stretch and deep drawing involved. It is necessary that the sheet metal is stretched as well as possible without reaching the material’s limits (e.g. splits, wrinkles).

There are approximately 300 to 400 sheet metal parts which fit together to form the body of a car. In order to manufacture high quality sheet metal parts optimally for their particular use, specialized software simulates the complete deep drawing process.

Hemming

Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to achieve a tight fit. Normally hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges.

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. Typical parts for this type of assembly are hoods, doors, trunk lids and fenders.

The accuracy of the hemming operation is very important since it affects the appearance of the surface and surface quality. Material deformations, which occur during the hemming process, can lead to dimensional variations and other defects in parts. Typical hemming defects are splits or wrinkles in the flange, material overlaps in the corner areas or material roll-in. This is why it is important to use simulation tools in order to, on the one hand, better understand the hemming process and, on the other hand, significantly reduce the number of “trial and error” loops during tryout und production.

There are various types of hemming operations:

  • Conventional die hemming
  • Roll hemming

Conventional die hemming

Conventional 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 and trimming operations have been completed. The formed flange is then hemmed in several process steps. These steps include, for example, the pre-hemming and final hemming depending on the respective opening angle of the flange. Production plants for conventional die hemming are very expensive, but the cycle times are very low.

Roll hemming

Roll hemming is carried out incrementally with a hemming roller. An industrial robot guides the hemming roller and forms the flange. Roll hemming operation can also be divided into several pre-hemming and final hemming process steps. Roll hemming is very flexible to use and tool costs are significantly lower as compared to those of conventional die hemming. However, the cycle times are much higher since the hemming is realized using a hemming roller which follows a defined path.

Final Assembly

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