OBJECTIVE:

     To Design the Back Door of a car by creating inner panel and outer panel with designing consideration and fix the reinforcements by Standards.

INTRODUCTION:

Back Door:

     The trunk or boot is main storage of the car which is often a hatch at the rear of the vehicle. It also called tail gate. These doors are open and closed by manually or automatically. In most luxury car door is automatically operated. It plays major roles during rear crush cases. So, we consider the strength and design this back door. Our design must obey crush requirements. The institute of highway safety analysis the different type of rear crash and give rate of the car. So, this rate depends upon material, embosses, flanges, type of joining, strength of material.

               

COMPONENTS OF BACK DOOR:

1.Back Door outer panel:

     Outer Panel is designed by the styling team to give good look. It is actually called the skin of vehicle.  It is hemmed with inner panel and cover the inner panel. This part isn’t welded with inner panel. Using of the sealant and mastic points are connected them and hood get good stiffness. Back door window, wiper and number board are fixed on the back door.                    

2.Back Door Inner Panel:

     It gives stiffness to the back door and support the outer panel of the hood. Its emboss parts and holes dissipates the force in different directions while vehicle takes crashes. So, very   less injures the human and car.    

 3.Striker:

      It is used to lock and unlock the back door in main body of car. It is one type of hook. It is assembled with back door by nuts.     4.Hinge assembly:

     The hinges are placed inside panel of back door. It is used to hood move upside and down side. It is rotating in an axis by rod or fixer. Striker and hinges are also called reinforcement. It increases strength also.             5.Gas stay:

     It is uses to open and close the back door automatically or manually. When the gas compresses this back door is open. It has rod type of arrangement. It is mostly used in high weight back door. Its cost is high. So, this type of arrangement is mostly fixed in high budget cars.               

         

 

Types of doors depending based upon working:

1.Top mounded Door              

2.Side mounded Door            

                      

Types of Back Door Operating:

  1.Manually operated by Gas stay:

     This type of car back door is very less weight. It is operated without heavy efforts. With the help of gas stays are used to operate the back door.                  

  2.Electrically operated by Gas stay:

     In this type gas stays are operated electrically. Heavy weight doors are operated by this operation. Mostly premium cars are used this method.                            

  3. Electrically operated car:

     This type of car back door is open and close electrically by remote controlling. HYUNDAI SANTTA car is intelligent remote control operated car.

                           

 

Parts Of Back Door:

1. Inner panel
2. Outer panel
3. Hinge reinforcement
4. Wiper motor reinforcement
5. Latch and Stricker reinforcement
6. Gas stay reinforcement.             

Materials:

      In past days steels are mostly used for back door. But it is heavy weight. So, it reduces the fuel efficiency and open and closing operations are quite difficult.  So, instant of steel aluminium are used in back door which is less dense material and suitable for complex shapes. We can give thickness locally by coating. If we are using aluminium, we can reduce the number of parts.

                       

Basic Manufacturing process of Sheet Metal Components:

      Deep drawing method is widely used to sheet metal forming.

Deep Drawing:

     It is one of the forming processes in which process combination of tensile and compressive pressure is given to change flat sheet to hollow sheet bodies.

     It is basically classified into three types depend on load application.

1. Deep drawing using tools
2. Deep drawing using active media
3. Deep drawing by means of active energy

     Deep Drawing using Tools method is mostly used in sheet metal forming.

Process of Deep drawing:

• The rigid tools consist of a punch, die and binder. This punch and die will be the product replica.
• In this process the holder closes after the sheet has been inserted.
• Then sheet is clamped on the die and binder hold the sheet
• The process will do slowly to prevent wrinkles forming under the binder.
• The punch pushes the sheet slowly get and the sheet gets die shape.
• The amount of punching force continually increased to lower dead centre of punch.
• In this process achieved in stretch purely decreased the thickness of the sheet metal.
• This is forming process in which only forming slightly curved and low depth product.
• This process is combination of stretch and deep drawing involved. So, in which process should stretched the sheet metal as well as possible without reaching material limits. If give low stretching in complex parts sometime it will give defects such as wrinkles and splits.

                     

                

EMBOSSING:

      It is one of the forming processes which is used to form raised, sunken and relief design. In this process male and female rollers are passed on both sides and give desired patten. This design is fully depended on the dies of the male and female rollers. There is no thickness reducing in this process.

    Characterises:

• Ductile sheet metal also formed in this process
• Production rate is medium to high
• Same thickness is got after processing
• Varity of Parten is available in this processing.
• Reproduces also done without variations.

                  HEMMING:

     Hemming is one of the cold joining processes which is used to join a sheet metal part on another part. Outer panel has flanges which flanges will fold on the inner panel bottom side which is permanently joined. It is done by traditional press or robotically controlled roller. This process mostly used for doors, hoods and decklids.

Types of Hemming:

1. Open hemming
2. Flattened/closed hemming
3. Tear drop hemming
4. Rolled/ rope hemming

           

BLANKING AND PIERCING:

• These two processes are used to cut the sheet metal to get desired hole features.
• In the blanking process push the punch and get required part. This final part is called blank which is separate from work piece and tool fixture. Remaining part in tool fixer which is called scarps.
• In the piercing process push the punch and unwanted part. It is called scarps. Final part is kept in the fixing tool. It is called washer.

                   

MASTIC SELANTS:

     Mastic sealant is a type of liquid sealant that cures an in elastic state. It gives bonding between two surfaces. It is one type of adhesives. In the hood model hood outer panel is aesthetic look. So, we can’t use fasteners. So, we use hemming and mastic sealant. Hemming only joined with outside part. But this sealant is used in the rest of part. It is one type of elastic component. Initially it is in semi solid form after curing it will come solid form additionally, which increases strength of the panel.

                   

Spot Welding:

      Spot welding is one of the joining processes which is used to join the two sheet metal parts. Heat the sheet then join the sheets. In the roof model directly not, visible parts are welded by this technique.

                 

 

Designing of BACK DOOR:

Designing Software:

              In this project we use NX CAD software which is one of the Computer Aided Designing software which is used to create 3D modelling, assembly the parts and drawing etc. It supports the product developing and manufacturing at all stage of life cycle.

METHODOLOGY:

Designing Methodolgy of a Back Door:

                  Designing Methodolgy of Surface Creating: 

Tools Used to design the Backdoor using NX:

Trim sheet:

     It is used to the sheets by curve or another sheet as tool.

Offset Surface:

     It is used to create copy of surface from a surface in required distance.

Law Extension:

     It is used to extrude the surface with required angle and length.

Trim and extend:

     It is used to trim two surfaces by which intersecting line. We can decide which part we keep or discard.

Through curves:

     It is used to create a surface between two curves or surface edges.

Emboss:

     It is used to create emboss feature which give offset surface and joined wall. We can modify wall draft angle also.

Curve on face:

     It is used to draw curve on the required face.

Projection curve:

     It is used to project an exciting curve on required part like surface, plane etc.

3D profile:

     It is used to draw 3D curve between two points with tangency.

Face blend:

     It is used to create blend edges or faces between faces.

Edge blend:

     It is used to create blend edges from sharp edges

Extend sheet:

     It is used to extend the sheet to required length.

Mirror geometry:

      It is used to mirror a part by reference like plane or surface which means create another part as well as given part on another side of reference.

Sew:

     This tool is used to combine the two surfaces to for a single surface part.

Extrude:

     It is used extrude the required profile and create surface or solid part.

Thicken:

     This tool is used to give thickness to the surface to create solid body.

Wave geometry linker:

     It is used extract the required part from another part which extracted part is used to create feature. It is mostly used for two components perfectly aligned in assembly.

 

DESIGNING OF BACK DOOR:

Inputs Given:

1. Outer panel thickness: 0.75 mm
2. Inner panel thickness: 0.75 mm
3. Reinforcements thickness: 1.5 mm

Class A surface:

     They have given outer panel class A surface which is used to make inner and outer panel of the back door. Some patches are in this give surface So, it is repaired and fixed then it is divided into upper and lower panel.

Designing:

                  

     First, we created the tooling axis of the back door. It is deep drawing direction of sheet metal.                     

     Then created the sealing flanges by offsetting the outer panel of the required distance.                 

     Then created inner panel of the back door by offsetting the outer panel in required distance.                  

     Then created connecting flanges to join inner and sealing flanges.                  

         Give embosses to this inner panel to increases the strength of the back door.               

     Create the gas stay,hinge and wiper motor mounding areas. Then Mirror the one side inner panel to get full inner panel of the back door.             

      Create latch & Stricker mounding area.                 

     In outer panel create the hemming flanges by offsetting and sweep comment. In this outer panel upper and lower panel are created separately.

                                          

     Give stress release cut at the corner of the hemming flanges.                    

     Then mirror and get full outer panel of the back door.                     

     Create the Hinge, wiper motor, gas stay, striker reinforcement separately by wave geometry linker from inner panel.

Draft analysis:

     Draft analysis is used to get the angle of the full surface. It is used to analysis the full components angle. It is help for determining the manufacturing feasibility of the back door.

CONCLUSION:

     The outer panel and inner panel of the back door, embosses, hemming flanges are successfully created and assembled. Draft analysis was performed on the inner panel and all reinforcements are created and placed at appropriate position.

Different types of views of Backdoor: