Design of backdoor

CAR BACK DOOR DESIGN

Aim: To design back door of car using given outer class 'A' surface.

What is back door of a car?

A door which is located at the rear side of a car which gives access for the boot space to store luggage, spare wheel etc.

These doors can be operated manually or electric powered. In most of the luxury cars door is electrically operated.

Types of doors based on working position,

1. Top Mounted Door
2. Side mounted Door
3. Bottom Door

Back Door Assembly:

• Inner panel
• outer panel
• hinge and its reinforcement
• wiper motor reinforcement
• latch & stricker and its reinforcement

Different Sheetmetal processes used for manufacturing the Back Door

Deep Drawing:

The metal deep drawing process is an effective method of manufacturing of cups, cans and other similar deep drawing products. The deep drawings having two main categories.

1. First- stage drawing: The blank shape of metal is placed on the die and contact with the punch. When the metal specimen is flat piece of sheet metal used in forming and finish the product. Initially the punch moves in downward direction. The outer rim of blank is subjected to pure radial drawing (drawing toward in vertical axes) between die and blank metal. The metal become a bend and sliding over die and also stretched between die and punch. The metal in vicinity of punch head and contact with it bend and slide over radii and stretch over punch head.
2. Redrawing: The components drawn from first stage again it is redrawn convert into more depth to form a cup shape in the die and punch. The second stage of drawing is called as redrawing.

Embossing:

Embossing is a metal forming process for producing raised or sunken designs or relief in sheet materials by means of matched male and female roller dies, theoretically with no change in metal thickness or by-passing sheet or a strip of metal between rolls of the desired pattern. Metal sheet is drawn through the male and female roller dies producing a pattern or design on the metal sheet. Depending on the roller dies used, different patterns can be produced on the metal sheet.

Materials commonly used in the metal embossing process include:

• Aluminum alloys
• Steel alloys
• Zinc
• Copper
• Galvanized steel
• Brass
• Cold rolled steel

Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to achieve a tight fit. Normally hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges.

In car part production, hemming is used in assembly as a secondary operation after deep drawing, trimming and flanging operations to join two sheet metal parts (outer and inner) together. Typical parts for this type of assembly are hoods, doors, trunk lids and fenders.

There are various types of hemming operations:

1. Conventional die hemming: In conventional die hemming, the flange is folded over the entire length with a hemming tool.
2. Roll hemming: In roll hemming, the hemming roller is guided by an industrial robot to form the flange.

Design of Back door in NX CAD:

Door parts thickness is given below,

1. Outer Panel - 0.75 mm
2. Inner Panel - 0.75 mm
3. Reinforcements - 1.5 mm

Parts Of the BackDoor

Inner Panel

Hinge Mounting Bracket ( LH & RH )

Gas Stay Bracket ( LH & RH )

Wiper Motor Support Bracket

Latch

Latch Reinforcement

Hinge reinforcement ( LH & RH )

Gas Stay Reinforcement ( LH & RH )

Given Data,

Then to improve the strength of the inner panel and to reduce the weight 'Y' type emboss and other cut-outs are created. Also, for Latch and Stricker mounting cut-out is created. This cut-out is also done on other side of the inner panel to maintain the centre of gravity of the Back door.

Parts Of the BackDoor

Inner Panel

Hinge Mounting Bracket ( LH & RH )

Gas Stay Bracket ( LH & RH )

Wiper Motor Support Bracket

Latch

Latch Reinforcement

Hinge reinforcement ( LH & RH )

Gas Stay Reinforcement ( LH & RH )

NNER PANEL

Inner door panel is a component which is use for strengthening the door assembly and it is one of the most important components on witch all accessories are mount like hinges, glass guide channel and gas stay.Back door inner panel is mounted with the the Roof.Inner is mounted with the outer panel with the help of hemming process.

• Materials used for the Inner panels are steels,Aluminum.
• For giving more strength to the inner panels by Adding extra reinforcements to strengthen the parts.

Above picture shows that the inner panel for Back door of a car.

In the Inner panel i used embosses,Outer panel and inner panel mounting area,space for Harness,Wind Glass Mount and fillets,No sharp corners.

Embossing

Embossing is a metal forming process for producing raised or sunken designs or relief in sheet material by means of matched male and female roller dies, theoretically with no change in metal thickness, or by passing sheet or a strip of metal between rolls of the desired pattern.

• Metal sheet is drawn through the male and female roller dies producing a pattern or design on the metal sheet. Depending on the roller dies used, different patterns can be produced on the metal sheet.
• Emboss should be in 7 degree to 25 degree inclinte in angle and it should not be in 90 degree angle,why because when we do stamping in manufacturing the stamping tool fits the sheet metal hence it will not come out of that sheet metal,So this is the main reason why the emboss face is in angle.

Characteristics of the metal embossing process include:

• Its ability to form ductile metals,
• Its use in medium to high production runs,
• The ability to maintain the same metal thickness before and after embossing,
• The ability to produce unlimited patterns, depending on the roll dies, and
• The ability to reproduce product with no variation.

• Located within the embossing stand itself are two engraved and mated hardened steel rolls, geared together to maintain top-to-bottom pattern registration. The width and diameter of these rolls depends on the strip width, material thickness, pattern depth, and material tensile strength and hardness.

• In most machines, the upper roll blocks are stationary, while the bottom roll blocks are movable. The pressure with which the bottom roll is raised is referred to as the tonnage capacity. This figure also depends on the aforementioned parameters.

• Embossing machines are generally sized to give 2" of strip clearance on each side of an engraved embossing roll. Many embossing machines are custom-manufactured, so there are no industry-standard widths. It is not uncommon to find embossing machines in operation producing patterns less than 6' wide all the way up to machines producing patterns 70"+ wide.

• The illustration that follows provides a two-dimensional look at a typical embossing line setup with an embossing roller in the middle. The illustration shows the metal sheet entering the roller, and then the embossed sheet leaving toward the drawing rollers.

• Embossed metals are used in industry for two reasons: aesthetic and functional. Aesthetic applications also include appliance panels, building products, elevator panels, garage door panels, automotive trim, metal office furniture, and others.

• Functional applications are those in which a performance characteristic is enhanced. This can include a metal products ability to disperse liquid more effectively, reduction friction and static, increase a metal panel’s stiffness and rigidity, increase a metal surface area for acoustic or heat transfer applications, and improve traction.

• The embossing process can produce a variety of patterns. Some of the most common patterns include stucco, leather grain, wood grain, weather grain, and rough sawn cedar. Most embossers will tool to form any needed pattern, depending on the cost parameters involved.

Materials commonly used in the metal embossing process include:

• Aluminum (All Alloys)
• Aluminum (T1/T2)
• Brass
• Cold rolled steel
• Copper
• Galvanized steel
• High strength, low alloy, steel
• Hot rolled steel
• Steel (All Alloys)
• Zinc

Cable Harness Gaps

I left some gap for Headlamp Harness and tailgate light harness cables.

Left some gap also dissipates the force when collision happens.

To much of cutting the inner panel leads to weaken the panel.

To reduce the impact to the occupants inside the car, additional latch and hinge reinforcement to the hood. When latch and striker are placed, there is drop in strength at that position thus reinforcement is required. Also stiffness pads are placed to reduce NVH. Hinge and latch reinforcement thickness is kept at 1.5 mm but it may vary.

Where there is movements like hinge,hood opening and closing,Doors etc,In this cases there is less strength in that particular opening and closing areas in that we need to add Reinforcement to giving the additional strength to that areas.

Hinge Reinforcement

What is HINGE ?

Hinges are simple mechanical bearing devices that are used to connect two parts and allow them to rotate relative to each other about a fixed axis. Depending on the type employed, the components can move (most commonly) within a limited arc or with 360° freedom.

Material Used for HINGE

Due to the applications in which they are applied, hinges need to be able to withstand the stress of consistent opening and closing. To fulfill this requirement, many hinges are made of stainless steel as the strength of steel materials allows the hardware to bear heavy components, and the stainless characteristics prevent rust and corrosion. The latter is important because hinges used in external applications, especially near the ocean or salt lakes, can experience fatigue and failure much quicker due to exposure to moisture and salt in the environment.

Position of latch and striker is perpendicular to the hinge then only the latch and striker mechanism works properly when the door closing and opening position.

For the proper opening and closing of the Door, the striker should be perpendicular to the trajectory of the Door. For this, hinge is assembled at its position. Once it is placed, hinge axis is drawn.

• To check the hinge axis as the center we draw a big circle to the position the latch in such a way that it is perpendicular to the hood trajectory.
• In between the two hinges the striker is perpendicular to the midpoint of two hinges,Why because while closing and opening of latch and striker the opening position be similar actions.

CONCLUSION:

Thus,For the provided styling surface of a back door design, I used appropriate design methodologies and provided the necessary reinforcements and embosses for the BackDoor design.thus i designed a back door.