Hood design-Week 2

Aim:

Design the 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 the Hood's Inner Panel, Outer Panel, Latch, Hinge and Reinforcements. 

 

Introduction

The hood is also a major part of a car. It provides a hinged cover to the engine compartment. It is also known as bonnet in British English. Covering the engine compartment hood also protects from causing injuries due to the Engine and the components at the front. There are a lot of factors to consider before designing the hood.

 

Hood and its Components:

• Hood Outer panel

• Hood inner panel

• Reinforcement

• Stifnnerpads

• Mastic seals

• Hood stay

 

Hood Outer pane:

It's an external part which provides the shape of the car's body. This part protects the engine and the components at the front from outside damage.

Hood inner panel:

This is the part of the hood which provides structural support and rigidity to the hood. The inner panel is the most complicated and heaviest part of the hood assembly.  The impact deformation zones should be considered When designing the inner panel along with other factors.

Reinforcement: 

It's a structural component which will provide extra strength and rigidity to those areas where extra weight acts on the hood. These reinforcements will help during an impact by absorbing some of the impact energy. They are assembled in between the Outer and inner panels of the hood.

Stifnnerpads:

It is a kind of form material to reduce noise and vibration and to improve some rigidity.

This is placed between the outer and inner panels. These can affect the cost and weight of the car.

 

Mastic seals:

It is a material used to bind the Outer and inner panels of the hood. It is also used to seal the gaps, joints and seams in the car. It provides improvements in the NVH of the hood.  Each seal will provide extra strength and rigidity for a distance of  80mm in diameter. They deliver a flexible, watertight barrier that safeguards against corrosion, moisture, and vibration.

Hood stay: 

The hood stay is the component which is used to keep the hood open. There are two hood stays one is a support rod/strut and the other is a gas stay. This stay is decided when designing the hood. The placement of the stay, the type of the stay and the design are decided according to the hood. The hood’s opening angle varies from country to country and that can be achieved by the hood stay design for the hood.

 

Design consideration

Latch Trajectory:

Latch Trajectory is important for the proper locking of the hood. If the latch trajectory is off by slightly the Sticker will not close properly.

The Circle is the latch trajectory path, which the sticker will follow to lock. The sticker should be facing tangent to the circle.

Mastic data:

Mastic points are the 25mm diameter circular for providing mastic sealant to provide rigidity.

 

Emboss:

The metal-forming process referred to as embossing generates raised or sunken designs on sheet metal. When designing a hood, embossing can be applied to redirect the force of impact from the hood's outer corners towards its hinge portions. Embosses are also created for the sticker and hinge mounting. Embosses are the places where joining of the inner and outer panels. Embosses are where Cutouts are also created.

Cutouts:

The cutouts in the emboss are to reduce the impact when a pedestrian collides with the hood.

Then also reduces weight and improves structural integrity.

Manufacturing Process:

Sheet metal drawing: 

Sheet metal drawing is used to create intricate structures and forms out of thin metal sheets. To create the required shape, a flat sheet of metal is drawn into a die cavity. Because of its cost-effectiveness and adaptability, this method is widely used in a variety of industries, including electronics, construction, automotive, and aerospace.

Hemming:

In sheet metal production, the hemming process is a popular method for attaching two sheets by folding one panel's edge over the other. The technique is very popular in the appliance, automobile, and aerospace industries where robust and beautiful seams are necessary. Hemming enhances the final product's appearance by creating neat, completed edges without obvious fasteners.

Designing hood in Siemens NX

STEP 1: TOOLING AXIS

• Imported the hood outer panel to the assembly.

• Trimmed two halves at the centre using the ZY plane.

• Created a new part in the assembly 

• Hide the Hood's outer panel part.

• Using wave geometry linker copied the surface of the hood outer panel in the newly created part.

• Unchecked the associative box and broke the link between the Hood outer panel part and the new part.

• Drawn a tooling axis sketch

 

STEP 2: Creating Flanges

• Offset the trimmed surface.

• Offset the edge curve to a 20mm distance on the surface.

• Trim the surface using that curve and crate the first flange.

• Again follow the previous steps of offsetting the surface and this time offset the boundary curves two times. First, offset at a distance of 22mm and the next at 35mm.

• Trim the area other than the in-between area of the offset curves and create the second flange

• Then the previous steps of offsetting the surface and this time offsetting the boundary curve a distance of 50mm.

• Trime the outside surface and create the third flange.

• Through curve is used to join the flanges

• Face blend is used to provide join and fillet the sharp bend edges.

 

STEP 3: Emboss creation 

• Create a sketch plane on the ZX plane and orientation along the X-axis.

• Sketch the required shape for the emboss on the ZX plane.

• Project the sketch on the surface

• Select the emboss option and provide emboss along the tooling axis direction.

• And provide edge blend at the sharp edges.

• Emboss 1

• Emboss 2

• Emboss 3

• Emboss 4

• Emboss 5

STEP 3: Cutout creation 

• Create a sketch plane on the ZX plane and orientation along the X-axis.

• Sketch the required shape for the cutout on the ZX plane.

• Project the sketch on the surface

• Trime the sketch from the sheet.

• Cutout 1

• Cutout 2

• Cutout 3

• Cutout 4

 

STEP 4: Hing mount

• Create a datum plane along a slight angle.

• Sketch the hing mount.

• Project the sketch onto the surface.

• Emboss the sketch and for a flat surface for the mount use the datum plane.

• Use edge blend to create the sharp edge fillet.

 

STEP 5: Mirror the geometry

Mirror geometry is used to mirror the half-trimmed sheet and sew both sides.

STEP 6: Striker mount

STEP 7: Assemble the striker and hing

STEP 7:Thickening the sheet.