Hood design-Week 2

                                                                              HOOD DESIGN              

HOOD IS A OPENING BODY THAT COVERS THE ENGINE COMPARTMENT OF THE CAR WHICH HAS THE ENGINE IN THE FRONT OF THE CAR. IT CONSISTS OF OUTER PANEL AND INNER PANEL.

OUTER PANEL 

OUTER PANEL IS NOTHING BUT A STYLING COVER OF THE HOOD THATS WHY WE DONT DO ANY MAJOR PROCESS ON THIS AS THIS MAKE THE OUTER BODY OF THE CAR LOOK BAD.                   

INNER PANEL

INNER PANEL IS THE ONE WHICH PROVIDES THE STRENGTH TO THE HOOD.WE GET THE SURFACE OF INNER PANEL BY OFFSETTING THE SURFACE OF THE HOOD SKIN THAT WAS PROVIDED TO US .INNER PANEL GIVES THE STRENGTH TO THE HOOD THATS WHY WE DO THE MAJOR PROCESSES ON THE INNER PANEL LIKE EMBOSSES,HINGE REINFORCEMENT,LATCH REINFORCEMENT.

                                                          DESIGN CONSIDERATION OF HOOD DESIGN

OPENING ANGLE 

THE FIRST MAIN CRITERIA TO DESIGN THE HOOD IS OPENING ANGLE. IT CHANGES FROM REGION TO REGION .LETS TAKE A EXAMPLE OF NEPAL AND UNITED STATES .THE OPENING ANGLE IN NEPAL IS LESS AS COMPARED TO THE UNITED STATES AS THE AVERAGE HEIGHT OF THE PERSON IN NEPAL IS LESS COMPARED TO U.S .

THE OPENING ANGLE IS SHOWN IN THE PICTURE BELOW.

TO HOLD THE HOOD IN THE OPENING POSITION WE MOUNT GAS STAY OR SUPPORT RODS.GAS STAYS ARE USED FOR THE HIGH PERFORMENCED CAR WHICH HAVE THE LENGHT OF THE HOOD MORE AND THE WEIGHT OF THE HOOD IS ALSO MORE.MORE THE OPENING ANGLE MORE THE LENGTH OF THE SUPPORT ROD.

SUPPORT ROD IS MOUNTED ON ONE SIDE .ON THE ENGINE COMPARTMENT OR ON THE HOOD.SUPPORT ROD SHOULD BE STRAIGHT OR CAN HAVE BEND. BEND CAN BE ANYWHERE IT IS NOT NOT NECESSARY THAT WE HAVE T GIVE BEND HERE OR THERE. 

BUT WE SHOULD KEPT INN MIND THAT IT SHOULD NOT COLLIDE ANYWHERE IN THE HOOD.AS IT WILL PRODUCE NOISE OR RATTLING SOUND WHILE MOVING OF THE CAR.

THE MAXIMUM CURVATURE THAT WE GIVE TO THE ROD CANT BE MORE THAN 35mm.

SUPPORT ROD OR GAS STAY SHOULD ALWAYS BE IN THE OPPOSITE SIDE OF THE BATTERY SIDE AS IT WILL MAKE EASY TO  MOUNT THE BATTERY.

GROMETS ARRE USED FOR SUPPORT ROD AND IN THE GAS STAY WE USE ADDITIONAL BRACKETS WHICH IS A KIND OF REINFORCEMENT. AND FROM WHERE WE HAVE A QUESTION WHAT IS A REINFORCEMENT ??

                                                                            REINFORCEMENT

WHENEVER WE ADD WEIGHT TO A MATERIAL WE LOOSE STRENGTH AT THAT PARTICULAR AREA , TO IMPROVE THE STRENGTH TO THAT PARTICULAR AREA LOCALLY WE PROVIDE  INTENTIONALY  EXTRA MATERIAL WHICH IS NAMED AS REINFORCEMENT..HERE ARE SOME EXAMPLE.

LATCH REINFORCEMENT

PICTURE SHOWN ABOVE SHOW THE LATCH AND STRIKER REINFORCEMENT. BECAUSE WE ATTCH LATCH AND STRIKER HERE THATS WHY WE NAMED IT AS LATCH REINFORCEMENT.

HINGE REINFORCEMENT

AS TO OPEN AND CLOSE THE HOOD WE NEED HINGES AND TO FIX THE HINGE . AND FOR THAT WE NEED TO GIVE WEIGHT TO THE HOOD INNER PANEL AND FOR THAT WE NEED TO GIVE THE HINGE REINFORCEMENT .

AS WE PLACE OUR HINGE ASSEMBLY HERE THATS WHY WE NAME NAME THIS AS HINGE REINFORCEMENT. WE PLACE HINGE ASSEMBLY BY GIVING CONSTRAINTS BETWEEEN THE HINGE ASSEMBLY AND THE  HOOD INNER PANEL.

1. TOUCH CONSTRAINT TO HINGE ASSEMBLY AND HOOD INNER PANEL

2.ALLIGN CONSTRAINT TO HINGE AND HOOD INNER PANEL

3.PARALLEL CONSTRAINT .

 PHOTO SHOW THE HINGE ASSEMBLY AND HINGE REINFORCEMNET AFTER THE CONSTRAINTS.

STIFFNER PAD

IT IS ALSO A TYPE OF  REINFORCEMENT WHICH IS A SPONGE TYPE MATERIAL.WHILE IN A MOTION THE HOOD VIBRATES FOR THAT WE PROVIDE THIS TYPE OF REINFORCEMENT . IT CAN BE REMOVED OR CAN BE GIVEN IN A HOOD. AND HERE COMES THE CONCEPT OF  N.V.H (NOISE VIBRATION AND HARDNESS).A CAR WITH GOOD NVH MEANS THAT THE CAR CABIN IS SILENT .WE CANT HERE THE ENGINME NOISE VIBRATION IN THE CABIN.

AS WE TALK ABOUT N.V.H THERE IS A ANOTHER TOPIC RELATED TO N.V.H KNOWN AS MASTIC.

MASTICS

IN THE FIGURE WE CAN SEE MASTIC POINTS.

EVERY MASTIC SEALENT HAVE A TENDENCY TO IMPROVE THE STRENGTH LOCALLY AROUND 80mm. AS WE HAVE HINGE REINFORCEMENT IN THE CORNERS SO WE DONT HAVE TO WORRY ABOUT N.V.H AT THE CORNERS.THATS WHY WE PROVIDE MASTIC IN MIDDLE OF THE HOOD. IT IS TYPE OF HARD RUBBER , WHEN IT GETS HOT IN THE FURNACE IT JOINS THE  INNNER AND OUTER PANEL TOGETHER.

 EMBOSSES

EMBOSES IS A PROCESS IN WHICH WE RAISE THE SURFACE OR SHEET AT A PARTICULAR PLACE. IT IS DONE WITH THE PROCESS LIKE DEEP DRAWING,MOULDING.WE WILL TALK ABOUT DEEP DRAWING LATER.

SO THE FIRST QUESTION IS HOW TO DESIGN AN EMBOSSES. THEIR IS NO SUCH CRITERIA THAT WE HAVE TO DESIGN IT LIKE THIS .THE MAIN CRITERIA  WE HAVE TO CONSIDER THAT DURING DESIGN WE MAKE EMBOSSES IN SUCH A WAY THAT IT WILL CHANGE THE DIRECTION OF THE ENERGY PRODUCED DUE TO THE COLLISION OF THE CAR FROM THE FRONT TOWARDS THE HINGE ASSEMBLY .WHICH RESULT THAT THE PERSON IN THE CAR WILL EFFECTED LESS FROM THE COLLISION EFFECT ASA IT WILL CHANGE DRASTICALLY.

THE MIDDLE EMBOSSES IS FOR THE LATCH SO HOW DO WE KNOW THAT IT IS PLACED AT THE RIGHT PLACE.WE HAVE TO MAKE LATCH TRAJECTORY.

LATCH TRAJECTORY

THE BLUE CIRCLE SHOWN SHOWS THE LATCH TRAJECTORY.HOW WILL WE MAKE IT.

FIRST WE HAVE TO MAKE A HINGE AXIS .BY DRAWING A LINE ON ONE POINT ON THE HINGE TO THE ANOTHER POINT OF THE ANOTHER HINGE.

AFTER THAT WE HAVE TO CRATE A POINT ON CENTER OF THE HINGE AXIS.AND FROM THAT CENTER WE HAVE TO MAKE A CIRCLE IN THE PLANE NORMAL TO THE INNER PANEL . CIRCLE CAN BE OF ANY RADIUS BUT IT SHOULD BE NOT SO BIG OR NOT SO SMALL.

AND THEN WE HAVE TO DRAW A LINE FROM THE CENTER UPTO THE CENTER AT A PARTICULAR ANGLE .IT SHOULD BE ON ANY ANGLE .

AND FROM THE POINT ON THE CIRCLE AND ON THE LINE.WE HAVE TO DRAW A LINE TANGENT TO THE CIRCLE .

AFTER THAT WE HAVE TO DRAW A LINE O N THE STRIKER SO THAT WWE SHOULD GET A POINT ON THE STRIKER.

FOR THAT FIRST WE HAVE TO MAKE A DATUM CSYS.AND AFDTER THAT DRAW A LINE RANDOMLY SHOULD BE IN THE MIDDLE OF THE STRIKER .AFTER THAT WE HAVE TO GIVE CONSTRAINTS TO THE TWO LINE WE HAVE ON THE STRIKER AND ON THE INNER PANEL.WE HAVE TO FIRST GIVE A TOUCH CONSTRAINT TO THE POINTS ON THE LINE,AND TOUCH CONSTRAINTS TO THE LINE AS WELL. AND AFTER THAT WE GET A STRIKER POINT.

FROM THIS LATCH TRAJECTORY WE CONCLUDE TO POINTS.

1. THE CIRCLE PATH IS THE TRAJECTORY OF THE HOOD CLOSING AND OPENING .

2.  THE STRIKER POINT IS PERPENDICULAR TO TRAJECTORY .

WE SHOULD ACHIEVE THIS PERPENDICULAIRTY FOR THE SMOOTH OPENING AND CLOSING OF THE HOOD.

HEMMING

AS WE HAVE THE OUTER PANEL WHICH IS OUR STYLING METAL COVER AND THE INNER PANEL WHICH WE MADE BY OFFSETTING OUR STYLING COVER .SO THE PROCESS BY WHICH WE JOIN THE INNER PANEL AND THE OUTER PANEL IS CALLED THE HEMMING.

IT IS DONE BY THE WRAPING AROUNG THE EXTRA STYING COVER ON THE INNER PANEL.

HEMMING IS DONE BY ROLLING PROCESS..AND DURING WE GENERALLY GET RED ZONES ...TO AVOID THAT RED ZONES WE GIVES RELIEFS IN THE CORNERS.

DEEP DRAWING

IT IS PROCESS BY WHICH WE CAN MAKE THE EMBOSSES.HOW IT IS DONE .THE SHEET IS PUT ON THE WORK TABLE.AND THE TOOL MOVES IN THE PERPENDICULAR DIRECTION TO THE SURFACE . THGE MAIN CRITERIA IS TO KEEP IN MIND THAT WE SHOULD GIVE A DRAFT ANGLE POSITIVE SO THAT AFTER DEEP DRAWING PRIOCESS THE TOOL SHOULD GO EASILY .IF WE SHOULD GIVE A NEGATIVE ANGLE TO THE EMBOSSES ....THE DRAWING BECOMES IMPOSSIBLE.