Design and development of automotive roof with necessary flanges and reinforcements

AUTOMOBILE ROOF

AIM : To design car roof with essential flanges and with reinforcement.

SOFTWARE USED : Siemens NX

OBJECTIVES :

• Design the roof with given styling class with essential reinforcement and bow roofs.
• Performing curvature study of roof for smooth designing.
• Caluculating the strenght of the bow roofs and reinforcement for heat distortion and snow load criteria.
• Performing Draft analysis.
• Performing Section modulus.

ROOF: An automobile roof or car top is the portion of an automobile that sits above the passenger compartment, protecting the vehicle occupants from sun, wind, rain, and other external elements.

SUNROOF: A sunroof is a movable panel that opens to uncover a window in an automobile roof, allowing light and fresh air to enter the passenger compartment. Sunroofs can be manually operated or motor driven, and are available in many shapes, sizes and styles. While the term sunroof is now used generically to describe any glass panel in the roof, the term "moonroof" was historically used to describe stationary glass panes rigidly mounted in the roof panel over the passenger compartment. A moonroof has a glass panel that is transparent and usually tinted. Previous terms include Sunshine Roof, Sliding Head and Sliding Roof.

A Car roof is the styling part of the car which gives an vehicle very royal an offical look .

The roof consists of BIW components of rails and panels inside of upper roof to stengthen & stiffness of the roof .

Ditch Area plays an important role in fixation of reinforcement and rails in BIW design.

The rails and reienforcements are spot welded to ditch area which are not considered as Styling surface

Factors considered before creating the Ditch area.

• Headroom clearence & field of vision
• Windshield assembly
• Backdoor assembly

PROCEDURE :

STEP-WISE apporach for design of automobile roof.

Class-A : Class A surfaces can be defined as any surface, that has styling intent, that is either seen, touched, or both and mathematically meets the definition for Bézier.

ROOF OUTERPANEL :

• Considering the half portion of the class A surface which is called as ditch area. Which Plays an important key role for design of the roof outerpanel ,rails and reinforcement.
• Since the roof has sharp edges to avoid sharp corners at edges and to consider smooth curvature using 5mm of smooth curving on all the sides.
• From the end of the roof front and side considering 15^degrees of law extension for creation of flanges.
• In frontal portion assembly of windshield is considered according to that 21mm of area is given for windshield.
• In my design consideration I have used sunroof which makes car more highlighted now-a-days only top-end cars are focusing on sunroofs.
• For styling the roof and highlighting it . I, have designed a Sketch and embossed it for look as well as strenghting from outside.

THICKNESS : 0.75mm

Design of Rare flange as per given mastersection :

• As per the requirements rare flange of the roof is designed.
• Avioding the sharp corners at edge of the rare flange making corner reliefs.
• Law extension of rare flange is 20mm in length and 55 degrees along 'z' vector in angle from there 15mm in length and 0 degrees along 'y' vector in angle and 35mm in length and 32 degrees along 'z' vector in angle and from 15mm in length and 0 degrees along 'y' vector and closing the flange area with 10mm in length and 10 degrees in 'z' vector .
• Considering the assembly of back door as per mastersection.

Mastersection For Rare Flange :

FRONT ROOF RAIL :

Mastersection for front roof rail

IMAGE OF FRONT ROOF RAIL :

Front roof rail makes strengthen the roof from upper to inside where windshield assembly also come in contact with roof therefore making them into strengthen FR rail is efficient one.

• Considering the Ditch area to be offseted of 32mm for FR Roof Rail as given in mastersection ,extend sheet for 6mm from front side so that the roof strenghting the windshield assembly .However 6mm of sealing is given in alignment of windshield and Flanges are prepared as mastic can be easily pass through FR roof rail.
• Creating Embosses for strengthing the Front roof rail and clearing the tool direction of 3^degrees in ejection.

CUT SECTION VIEW OF FRONT ROOF RAIL :

THICKNESS : 0.75mm

CENTER REINFORCEMENT :

Centre reinforcements come in the centre of the roof which gives roof more rigidity and strength for roof in bending moment and collision.Reinforcement is attachted with a roof rail and bow roof which are both spot welded to side flange with each other to give more strength to component. As given by the styling class reinforcement to be designed as per the standards.

Offseting the ditch area which is breaked linked body of roof in design for roof rail and centre bow roof.

CUT SECTION VIEW OF CENTRE REINFORCEMENT :

THICKNESS : 0.75mm

BOW ROOF 1 :

Bow roofs play a major role in deign of automotive roof in case of more bow roofs more stronger the roof is. Here, bow roof is designed and strenghten to roof crash and bending test.

Mastersection for bow roof

THICKNESS : 1.75mm

BOW ROOF 2 :

THICKNESS : 1.75mm

REAR ROOF RAIL :

CUT SECTION VIEW OF RARE FLANGE :

THICKNESS :1.75mm

ROOF GUARDS :

The biggest benefit of a car roof guards is that it can help the driver balance the weight of a vehicle by transferring some on to the top. In the modern day scenario, wherein mobility is everything, information broadcasting people use the rail to mount a dish antenna in the car.

THIS CAN BE taken from parents class or can be newly designed

SHARK FINS : The shark fin antennas are for UHF and microwave signals. The services that shark fins cover include satellite radio, GPS, tire pressure monitoring, and GM's OnStar. These services can't be accommodated with traditional whip antennas.

IMAGES OF AUTOMOTIVE ROOF :

CURVATURE CASE STUDY FOR ROOF DESIGN :

CASE STUDY	RELATION	Rx(mm)	Ry(mm)	W	RESULTS
CASE 1	BOW 1 -REINFORCEMENT	2967.6	2883	1.54	OK
CASE 2	REINFORCEMENT -BOW 2	3290.5	3762.7	1.65	OK
CASE 3	BOW 2 - REAR ROOF	2428.5	74204.6	2.07	OK

SECTION MODULUS :

Front roof rail:

Centre reinforcement :

Bow roof 1 :

Bow roof 2 :

Rear roof rail :

DRAFT ANALYSIS :

NOTE: ALL THE PARTS ARE CREATED WITH PROPER TOOL OPENING DRAFT ANGLE OF 3 DEGREES AND MORE THEN 3 DEGREES.

REAR ROOF RAIL :

BOW ROOF 1:

BOW ROOF 2 :

ROOF GUARD:

FRONT ROOF RAIL :

CENTRE REINFORCEMENT :

ROOF OUTERPANEL :

OVERVIEW :

• Design of BIW component Roof is done .Learning how to caluculate heat desitortion and section modulus.
• Learned to create rails with standards.