Hood design-Week 2

AIM:- To design the hood of a car with the given input panel and its dimensions.

Hood introduction:- The hood (north america english) or bonnet (commonwealth english) is the hinged cover the engine of motor vehicle hoods can open to allow access to the engine component or truck (boot in commonwealth english) on rear_engine an some mid-engine vehicles) for maintanance and repair.

A car hood also referred to as a bonnet in same other countries is the highest cover the engine of a front- engine vehicles. its purpose is to provide access to the engine for repair and maintenance car hood are typically constructed from steel and sometimes from aluminum.

In UK terminlogy, a hood refers to a fabric covering over the passenger compartment of the car ( known as the ''roof'' or ''top'' in the USA) for many motor vehicle built in the 1930s and 1940s, the resemblance to an actual hood is clear when it is open and viwed from the front :n modern vehicle it still serves the same purpose, but no longer resembles head covering.

on front - engines cars, the hood may be hinged at either the front or the rear edges or in earlier model (e.g the ford model T) it may be split into two sections, one on each side hinged arches into one section and allow the entire front bodywork to tilt forward around a pivot near the front of the vehicle.

Hoods are usually made the same as the rest of the body this can be steel, aluminum, fiberglass, or carbon fiber some aftermarket companies produce fiberglass or carbon fiber steel hood replacements to make the vehicles lighter.

The hood release system is common on most vehicles and typically consist of an innear latch/handle, a hood release cable and a hood look assemble. the hood lock handle located under the steering wheel, next to the driver's seat, or in the door frame.

HOOD DESIGN:-

There lot more thing before the hood gets in to designing hands that to be considered.

The height of the hood is designed based on the country standard as the height of a average changes from place to place.

The material consideration is also required that should be cost effective to manufacturing

The should be designed with a light weight for the pedestrain saftey as the the person hit to hood there should be minimal hard to the person

The input design for the input panel is given below;

The outer panel given is shown below:

so according to the input given the outer model should be modified to get the final input panel model.

first the outr panel should be exactley halfed into middle using mid plane and should work on the half anel.

Then all the feature should be mirrored and sewed together.

Now the feature are to be built up like embosses, mastic points, embosses for hinges and latch.

the law extension command is used to combine edge and the offseted surface.

Through curve command is used to join between the both upper face and the lower offset faces.

Now embosses should be create on the innear panel for removing material to get a light weight component.

Below image is shown for mastic embosses and the hinge embosses.

To stick the innear panel with the outer panbel mastic point were created and the maximum distance between them should be 5mm.

So after completing the mastic the innear panel should be mirrored and sewed together.

Then the sewed feature should be examined with geometry to check any cracks were built in between.

here geometry check is performed the green color is shown so that no errors were present and if it is shown in red marks then it indicates there present some error in joining the mirrored part.

Now the hinges should be attached at the ends of the embossed innear panel edges.

HINGE PLACEMENT:-

first hinges are placed on to the embosses and as innear panel is applied with fixed constraint hinge is placed parallel and touch constaint.

Then the hinge is mirrored with assocative connection to other side to get the same hinge postion on other side of the innear panel.

LATCH ATTACHMENT:-

The latch/striker is position from the basic of hinges centre point.

two points is marked from the two hinge axis and a line is drawn from the two points

Now a circle is drawn as that point as a centre with a radius of approximately 300 mm (based on the hood designer) and the tagent line is drawn on that circle.

then latch is coincided with that tangent line.

So after latch position is fixed then the emboss is create from the latch surface using wave geometry linker in to the innear panel file.

striker emboss is shown in the below image.

HEMMING OPERATION:

Hood outer panel:

HEMMING OPERATION

Hemming is a forming operation in which the edges of the sheet are folder or folded over another aprt in order to achive a tight fit normally hemming operations are to connect parts together to improved the apperance of a part and to reinforce part edges.

In car part production, hemming is used in assemble as a secondary operation after deep drawing trimming and flanging operation to join two sheet metal parts (outer and inear ) together. typical part for this type of assemble are hoods dopors truck lids and fenders.

The accuracy of the hemming operation is very important sice if affects the apperances of the surface quality material defrimation, which accure during the hemming processes can leads to dimenasion variation and other defects in parts typicaly hemming area are material roll-in this is way it is material overlap in the corner areas or material roll-in this is way importamnt to use simulation tols in order to on the one hand, better understanding the hemming process and, on the other significantly reduce the number of trial and error'' loop during tryout and production.

There are various types hemming operations.

. Conventional die hemming

Rool hemming

Conventional die hemming:-

Conventional die hemming is suitable for mass production. in die hemming the flange is folder over the entire lenght with a hemming tool. normally the actual hemming is a result of a forming operation in which the flage is formed with a hemming tool after the drawing and trimming operation have been complete the form flage is then hemmed in the several process steps. these steps includes depending on the die hemming are angle of the flage production plants for conventional die hemming are very expensive but the cycle times are very low.

ROLLING HEMMING:-

Roll hemking is carried out incrementally with a hemming roller an industries robot guide the hemming roller and forms the flage hemming operation can also be divided into several pre-hemming and final hemming process step. roll hemming is very flexible to use and tools costs are significantly lower as compared to those conventiobal die hemming. howver the cycle times higher since the hemming is realize using a hemming roller follower a define path.

A corber relief are provided at the edges of hemmed part to provide corner reliefs

Given outer panel data:

The outer panel is first offset to the distence below inner panel with alll thickness and allowances are provided and using law extension command and face blend command process is done.