DESIGN OF BACKDOOR

OBJECTIVE: The objective of this report is to document the design process and considerations involved in creating the backdoor of a car using Class A Surfaces in NX CAD. The report will outline the steps taken to develop the upper and lower panels, the creation of the inner panel and various mountings, and the incorporation of reinforcements and embosses for stiffness and impact resistance. Additionally, the report will highlight the use of cutouts for weight reduction and the implementation of the hemming process. The objective is to provide a comprehensive overview of the design decisions and techniques employed in the development of the backdoor, ensuring adherence to design specifications and industry standards.

 

ABSTRACT: This report presents the design process and considerations involved in developing the backdoor of a car using Class A Surfaces in NX CAD. The project encompassed the creation of upper and lower panels, as well as an inner panel, each with a thickness of 0.75mm. Additionally, various mountings, including hinges, gas stays, wiper motor, and latch and striker, were integrated into the design, with corresponding reinforcements. Despite limitations in the hinge axis accuracy due to the absence of the latch and striker parts, a possible hinge axis was established for the opening and closing mechanism. Adhering to the draft direction and tooling axis direction, all components were meticulously designed. The implementation of embosses on the inner panel aimed to redirect impact forces from rear collisions upwards, enhancing the backdoor's rigidity and stiffness. Furthermore, the strategic incorporation of cutouts facilitated weight reduction. This report provides a comprehensive overview of the design decisions made by a design engineer to ensure functional and aesthetically pleasing backdoor design, taking into account industry standards and best practices.

 

INTRODUCTION:

Different types of car backdoors are based on their mounting positions: top-mounted, rear-mounted, and side-mounted. Each type offers unique benefits and is commonly used in specific types of vehicles.

Top-Mounted Backdoors:

Trunk-style Backdoor: This type of backdoor is typically found in sedans. It is hinged at the top and opens upward, allowing access to the trunk compartment. Trunk-style backdoors are often top-mounted, providing a clean and streamlined appearance to the vehicle's rear end. They are commonly used in sedans due to their practicality, ease of access, and space efficiency.

 

Rear-Mounted Backdoors:

Liftgate Backdoor: Liftgate backdoors are commonly found in SUVs and crossovers. They are rear-mounted and consist of a single unit that includes the rear window and the trunk. Liftgate backdoors are hinged at the bottom and open upward, providing a wide opening for convenient access to the cargo area. This design is popular in SUVs as it offers versatility, allowing for easy loading and unloading of larger items.

 

Tailgate Backdoor: Tailgate backdoors are typically used in larger SUVs or trucks, particularly those designed for off-road use or heavy-duty applications. This backdoor is divided into two parts: the upper section includes the rear window and can be opened independently, while the lower section opens downward like a traditional tailgate. Tailgate backdoors provide a flat surface for seating or loading heavy items and are commonly used in vehicles where practicality and utility are prioritized.

 

Side-Mounted Backdoors: Side-hinged doors, also known as side-opening doors, are commonly found on vans, pickup trucks, and certain commercial vehicles. They are designed as single or dual doors mounted on the side of the vehicle, swinging outward to provide access to the storage compartment. These doors offer a wide opening, making it easy to load and unload cargo or luggage. They provide convenience and lower lift-over height compared to rear-mounted doors or tailgates. Side-hinged doors allow for independent access to different sections of the storage area, enhancing organizational flexibility. However, they require sufficient clearance on the vehicle's side and may impact aerodynamics and fuel efficiency. Overall, side-hinged doors offer practicality and convenience for accessing the storage area in vehicles designed for transportation, delivery services, or commercial purposes.

 

The different types of backdoors found in cars, SUVs, and sedans are as follows:

• Sedan Backdoor: Sedans typically have a trunk-style backdoor that opens upward. It provides access to the trunk compartment, allowing for easy loading and unloading of cargo. Sedan backdoors may feature a separate rear window that can be opened independently for quick access to the trunk.

 

• Hatchback Backdoor: Hatchbacks have a backdoor that combines the rear window and trunk into a single unit. This type of backdoor opens upward, similar to sedans, but provides a larger opening, allowing for easier loading of larger items. Hatchback backdoors are hinged at the top and can be fully opened.

 

• SUV Backdoor: SUVs often have two types of backdoors:

1. Liftgate Backdoor: Most SUVs feature a liftgate backdoor, which is a single unit that includes the rear window and the trunk. The liftgate can be opened upward, providing access to the cargo area. It offers a larger opening compared to sedan backdoors, making it convenient for loading and unloading bulky items.
2. Tailgate Backdoor: Some SUVs, particularly larger ones or those designed for off-road use, have a tailgate backdoor. This backdoor is divided into two parts, with the rear window opening separately from the lower trunk section. The tailgate backdoor can be opened horizontally, providing a flat surface for sitting or loading heavy items.

 

• Crossover Backdoor: Crossovers, which combine features of both sedans and SUVs, typically have a liftgate-style backdoor. This design allows for a versatile cargo area while maintaining a sleeker, sedan-like appearance.

These are the primary types of backdoors found in cars, SUVs, and sedans. However, it's important to note that there may be variations and unique designs within each category, depending on the specific vehicle model and manufacturer.

 

MAIN REPORT:

The design of the backdoor plays a crucial role in the overall aesthetics, functionality, and safety of a car. It is essential to consider various factors and design considerations while creating the backdoor using Class A Surface and CAD software like NX CAD. 

 

1. Surface Design:

The Upper and Lower Panels of the backdoor are created using Class A Surfaces. These surfaces need to have a high level of smoothness, curvature, and continuity. Class A Surfaces are typically used for exterior body panels to achieve a flawless appearance. The surfaces should be free from any imperfections, such as waviness or ripples, to ensure a premium finish.

 

2. Thickness and Material:

The thickness of each part of the backdoor is crucial for structural integrity and weight management. In this case, the thickness is set to 0.75mm, which is a common thickness for lightweight automotive parts. The material selection for the backdoor should consider factors like strength, stiffness, and impact resistance. Common materials used for backdoor construction include steel, aluminium, or composites.

 

3. Mounting Points:

The backdoor needs to be securely attached to the car body. Mounting points for various components like hinges, gas stays, wiper motor, and latch and striker are designed to ensure proper functionality and durability. Reinforcements are added around these mountings to provide additional strength and prevent any potential failure or deformation.

 

4. Hinge Axis:

The hinge axis is a critical component of the backdoor's opening and closing mechanism. While the exact hinge axis design may not be accurate without the latch and striker parts, creating a possible hinge axis in the CAD software helps visualize the movement and alignment of the backdoor. This allows for a better understanding and evaluation of the overall design.

 

5. Draft Direction and Tooling Axis:

Consideration of the draft direction is essential to ensure proper moldability and manufacturability of the backdoor. The draft is the angle or taper given to the surfaces to facilitate the removal of the part from the mould during the manufacturing process. The tooling axis direction is also considered to align the surfaces with the tooling requirements.

 

6. Hemming Process:

The hemming process involves folding or bending the edges of the backdoor to create a seamless joint. In NX CAD, specific tools are utilized to simulate and create the hemming process. Hemming not only enhances the overall appearance of the backdoor but also improves its structural integrity and provides resistance against water ingress.

 

7. Impact Resistance and Stiffness:

To ensure safety in the event of a rear impact, the inner panel of the backdoor is designed with embossed regions. These embosses are strategically placed to direct forces in an upward direction, away from the inside of the car. By doing so, the embossed regions help increase the stiffness and rigidity of the backdoor, minimizing the risk of intrusion into the passenger compartment.

 

8. Weight Reduction:

Weight reduction is a crucial consideration in modern automotive design to improve fuel efficiency and overall performance. Cutouts are incorporated into the inner panel of the backdoor to reduce weight wherever possible while maintaining structural integrity. These cutouts are carefully designed to avoid compromising the strength and functionality of the backdoor.

 

In summary, the design of the backdoor using Class A Surface and CAD software involves considerations such as surface smoothness and continuity, thickness and material selection, mounting points and reinforcements, hinge axis visualization, draft direction and tooling axis, hemming process, impact resistance and stiffness, and weight reduction. Each of these considerations is essential to ensure a well-designed, functional, and safe backdoor for the car.

 

To initiate the design process, we will start by utilizing the provided Class A Surfaces for the Upper and Lower Panels of the backdoor. These surfaces serve as the foundation for creating a visually appealing and high-quality design. By utilizing these surfaces, we can ensure a smooth and continuous appearance for the backdoor. Let's begin by carefully analyzing and leveraging these Class A Surfaces to create a well-crafted and aesthetically pleasing backdoor design:

CLASS A SURFACE OF THE UPPER AND LOWER PANEL: 

 

UPPER PANEL:

 

LOWER PANEL:

 

TOOLING AXIS CREATION:

 

First, We're going to use the Class A Surfaces to create the Inner Panel of our Backdoor. 

We're going to offset the selected surfaces from the Class A Surface to create our Sealing Flange.

 

What is a Sealing Flange? 

The sealing flange in the backdoor of a car refers to a specific feature that is designed to ensure a tight seal between the backdoor and the rest of the vehicle's body. It is typically a raised edge or lip that runs along the perimeter of the backdoor opening.

The primary purpose of the sealing flange is to prevent the entry of water, dust, and other external elements into the car's interior. It plays a crucial role in maintaining the vehicle's integrity, protecting the occupants, and preserving the overall functionality of the car.

The sealing flange helps to create a barrier that prevents water from seeping into the car during rainfall or when driving through wet conditions. It also helps to minimize noise and vibrations, contributing to a quieter and more comfortable interior environment.

In addition to its functional benefits, the sealing flange also plays a role in enhancing the overall aesthetic appeal of the car. It provides a clean and finished look to the backdoor, ensuring a seamless integration with the rest of the vehicle's design.

Overall, the sealing flange is an essential component of the backdoor design, serving both functional and aesthetic purposes by ensuring a secure seal and enhancing the overall performance and appearance of the car.

 

 

    

To create the desired sealing flange shape, we will utilize the 'Offset Curve in Face' option available in the 'Curve' Toolbar. This tool allows us to create a parallel curve that follows the contour of the backdoor surface.

In addition, we will also make use of the 'Bridge Curve' option, which enables us to connect two curves and create a smooth transition between them. This will help us achieve the desired shape for the sealing flange.

By combining these tools, we can accurately define and generate the required geometry for the sealing flange. This approach ensures precision and control in creating the desired shape while maintaining the integrity of the backdoor design.

Let's proceed with utilizing the 'Offset Curve in Face' and 'Bridge Curve' options to create the sealing flange shape as depicted in the provided reference. This will result in a well-defined and functional sealing flange that enhances both the aesthetics and functionality of the backdoor design.

Now, using the 'Bridge Curve' option, we're going to create curves that we can use later to connect these two surfaces with each other as shown below:

Maintaining tangency at a value of '1' using the Tangent Magnitude method in the shape control module when creating a Bridge Curve is crucial for achieving visual continuity, surface quality, design intent alignment, and manufacturability. This approach ensures a smooth and seamless transition between curves or surfaces, resulting in a visually pleasing design. It reduces the likelihood of surface imperfections and accurately represents the intended design. Additionally, it facilitates efficient manufacturing processes by enabling the creation of molds or dies with smooth transitions and reducing potential issues. Overall, maintaining tangency at '1' enhances the overall quality and aesthetics of the surface while ensuring alignment with design and manufacturing requirements.

The 'Through Curve Mesh' option in NX CAD is a preferred choice when creating surfaces due to its ability to accurately represent complex shapes, provide greater control, and handle intricate design requirements. It allows designers to achieve more realistic and visually appealing results, enhancing the overall quality and realism of the design. So, we're going to use this option to create the connecting surface between these two previously shown surfaces as shown below:

    

 

Now, we're going to offset our next surface required to create the Sealing Flange by 80mm as shown below:

Then, we'll use the 'Untrim' option on it to untrim the surface and work on it as shown below:

    

Again, we'll use the 'Offset Curve in Face' & 'Bridge Curve' options to create necessary guide curves and trims to connect these surfaces with each other before using the 'Through Curve Mesh' option to create the connecting surface between these surfaces. 

The remaining part of the Sealing Flange will be created using a similar approach, resulting in the final design as shown below:

 

After this, we'll create a 'Law Extension' that will be used to create the adjacent surfaces of the inner panel residing beside the sealing flange as shown below:

To seamlessly connect and ensure a smooth transition between the two surfaces of the Sealing Flange, we utilized the 'Face Blend' option available in the Surfaces Toolbar. This method not only maintains visual continuity but also ensures that the resulting design is suitable for manufacturing processes. 

 

Next, we're going to use the 'Trim & Extend' command to trim the above surface with the offsetted Class A Surface of both Upper and Lower panels that is offsetted by 1.7mm from the initial Class A Surface as shown below:

 

We will now incorporate the required blends using the 'Edge Blend' option found in the Surface Toolbar. This will be done to achieve the desired design outcome, as demonstrated in the image below.

 

Now, we'll work on the creation of the Windshield Area for the Backdoor. First, we'll extract the necessary surface from the Class A Surface as shown below:

 

Then, we'll use the 'Extend Sheet' option to extend it along the required direction as shown below:

 

Then, we'll create a 'Law Extension' along the required direction as shown below:

 

Next, we'll use the 'Trim Sheet' option to trim the extended sheet with this law extension but we'll make sure they're not joined together just yet after the trim operation.

 

Now, we'll create the second 'Law Extension' as shown below:

 

After that, we'll use the 'Offset Curve in Face' option to trim the second law extension at the top section and create a 'Bridge Curve' using which we can create a curve that will allow us to build a surface smoothly transitioning from the end of the first law extension to the second law extension as shown below:

 

Next, we're going to create two 'Bridge Curves' using which we'll create the surface below the Windshield where we'll eventually create the required embosses and cutouts as shown below:

The above surface is made using the 'Through Curve Mesh' option to ensure more control and flexibility over the surface that we're going to create.

 

Then, we're going to extend the above surface and the law extension adjacent to it in the required direction using the 'Extend Sheet' option as shown below:

 

Next, we're going to do a 'Face Blend' operation between the surfaces and provide necessary blends to the other regions as well as shown below:

 

Next, we will proceed to create the necessary mountings, including the Hinge Mounting, Gas Stay Mounting, Latch and Stricker Mounting, and Wiper Motor Mounting. This will be accomplished by creating sketches and utilizing the 'Law Extensions' feature, as exemplified in the provided image.

 

1. Hinge Mounting:

 

2. Gas Stay Mounting:

 

3. Latch and Stricker Mounting:

 

4. Wiper Motor Mounting:

 

Next, we're going to create the Mastic Region with respect to the Class A Surface.

 

To ensure the appropriate distance and adhere to design considerations, the surface designated for the application of Mastic Fluid is positioned 5mm away from the Class A Surface. This particular surface is extracted and offset from the Class A Surface itself, guaranteeing the desired distance is maintained.

 

Now, we're going to create the required embosses and cutouts on the surface below the windshield surface as shown below:

Embosses and Cutouts play crucial roles in the Automotive Industry when it comes to sheet metal parts. Let's explore each aspect in detail:

A) EMBOSSES:

An emboss is a raised feature created by deforming the sheet metal material. It serves several purposes:

• Structural Reinforcement: Embosses can enhance the rigidity and strength of sheet metal parts, improving their overall structural integrity. This is particularly useful in components that experience high loads or need additional support.

 

• Aesthetic Appeal: Embosses can be strategically designed to enhance the visual appeal of automotive parts. They add depth, texture, and visual interest to the surface, enhancing the overall design aesthetics.

 

• Branding and Identification: Embosses can be used to incorporate logos, brand names, or identification marks on automotive parts. This helps in brand recognition and easy identification of components during assembly or maintenance.

 

• Noise and Vibration Control: Embosses can be employed to dampen noise and vibrations by altering the acoustics of the sheet metal part. This is particularly useful in reducing unwanted noise in vehicle interiors.

 

• Heat Dissipation: In scenarios where heat dissipation is critical, embosses can be strategically designed to increase the surface area, improving thermal management and preventing overheating.

 

B) CUTOUTS:

Cutouts involve removing portions of the sheet metal material to create openings or voids. They serve various purposes:

• Weight Reduction: Cutouts help reduce the overall weight of automotive components, contributing to improved fuel efficiency and performance. By removing excess material, the part becomes lighter without compromising structural integrity.

 

• Functional Integration: Cutouts can be used to integrate other components or features into the sheet metal part. For example, cutouts can accommodate sensors, wiring harnesses, or mounting points for other parts, streamlining assembly processes.

 

• Ventilation and Cooling: Cutouts can be strategically positioned to provide ventilation and cooling for components that generate heat, such as engines, brakes, or electronics. This helps dissipate heat and maintain optimal operating temperatures.

 

• Fluid Flow Management: Cutouts can be designed to facilitate the flow of fluids, such as air, coolant, or fuel, in automotive systems. They ensure proper circulation and prevent pressure build-up or fluid blockages.

 

• Styling and Design: Cutouts can be utilized to create unique design elements, patterns, or visual accents on automotive parts. They contribute to the overall aesthetics of the vehicle, making it visually appealing and distinctive.

 

In summary, embosses and cutouts in the Automotive Industry offer a wide range of benefits, including structural reinforcement, visual appeal, branding, noise control, weight reduction, functional integration, ventilation, fluid flow management, heat dissipation, and design flexibility. Automotive designers and engineers strategically employ these features based on specific requirements, considering factors like performance, safety, aesthetics, and manufacturing feasibility.

 

FRONT-VIEW:

 

REAR-VIEW:

 

ISOMETRIC VIEW:

 

Now, we're going to create reinforcements for each of the mountings.

Reinforcement plays a critical role in mountings such as hinge mounting, gas stays mounting, latch and striker mounting, and wiper motor mountings in the Automotive Industry. Let's explore the importance and various aspects of reinforcement for each mounting:

 

1. Hinge Mounting:

Hinge mountings are responsible for providing rotational movement and stability for components like doors, hoods, or trunk lids. Reinforcement in hinge mountings offers the following benefits:

 

• Structural Integrity: Reinforcements ensure that the hinge mounting can withstand the forces and stresses associated with repeated opening and closing of doors or other moving parts. This prevents premature wear, fatigue, and potential failure.

 

• Load Distribution: Reinforcements distribute the load evenly across the hinge mounting, reducing localized stress concentrations. This is crucial in scenarios where heavy doors or components need to be supported to prevent sagging or misalignment.

 

• Durability and Longevity: Reinforcements enhance the overall durability and longevity of hinge mountings, ensuring they can withstand harsh environmental conditions, vibrations, and impacts over the vehicle's lifespan.

 

• Safety and Crashworthiness: In the event of a collision, reinforced hinge mountings provide increased structural integrity, contributing to the overall crashworthiness of the vehicle. This helps maintain passenger safety and protects the integrity of the vehicle's structure.

 

Steps to create Reinforcements:

A) To create reinforcements, utilize the 'Extract Geometry' option to extract the surfaces that will be used.

 

B) Now, we have to make cutouts in this extracted surface and hence we're going to create a sketch that will be projected on the surface and then we will trim that surface with respect to the projected curves. 

 

3. Offset the surface by 0.75mm upwards to align with the upward thickening of the Inner Panel. This ensures that the trimmed surface of the hinge reinforcement can also be offset and thickened in the same direction.

The rest of the reinforcements will be created in a similar fashion.

 

2. Gas Stay Mounting:

Gas stay mountings are used to support and control the opening and closing movement of hoods, trunks, or tailgates. Reinforcement in gas stay mountings offers the following advantages:

 

• Load Bearing Capacity: Reinforcements ensure that the gas stays mounting and can bear the weight of heavy hoods or tailgates without failure or deformation. This prevents issues such as hood drooping or unexpected closing due to insufficient support.

 

• Stability and Control: Reinforcements enhance the stability and control of gas stay mountings, enabling smooth and controlled movement during opening and closing operations. This ensures user convenience and prevents sudden movements that could pose safety risks.

 

• Vibration and Noise Reduction: Reinforcements help dampen vibrations and minimize noise generated during the operation of gas stay mountings. This enhances the overall user experience and contributes to a quieter interior cabin.

 

3. Latch and Striker Mounting:

Latch and striker mountings are responsible for secure closure and locking mechanisms in doors, hoods, or tailgates. Reinforcement in latch and striker mountings provides the following benefits:

 

• Security and Anti-Theft: Reinforcements enhance the strength and resistance of latch and striker mountings against forced entry or tampering. This ensures the security of the vehicle and prevents unauthorized access.

 

• Alignment and Engagement: Reinforcements help ensure proper alignment and precise engagement between the latch and striker, resulting in smooth and reliable operation. This prevents issues such as misalignment, rattling, or accidental opening of doors or compartments.

 

• Impact Resistance: Reinforcements increase the impact resistance of latch and striker mountings, making them more capable of withstanding external forces, such as side impacts or collisions. This contributes to the overall safety and crashworthiness of the vehicle.

 

4. Wiper Motor Mounting:

Wiper motor mountings secure and support the wiper motor assembly responsible for the windshield or rear window wiper functionality. Reinforcement in wiper motor mountings provides the following advantages:

 

• Vibration Damping: Reinforcements help dampen vibrations generated by the wiper motor, reducing noise and improving the overall user experience inside the vehicle.

 

• Stability and Alignment: Reinforcements ensure the stable positioning and alignment of the wiper motor assembly, enabling efficient and effective wiping action. This prevents issues like uneven or inconsistent wiping patterns.

 

• Durability and Reliability: Reinforcements enhance the durability and reliability of wiper motor mountings, ensuring they can withstand the continuous movement and environmental stresses associated with wiper operation. This contributes to long-lasting performance and functionality.

In summary, reinforcement in mountings such as hinge mounting, gas stay mounting, latch and striker mounting, and wiper motor mountings in the Automotive Industry is vital for structural integrity, load-bearing capacity, durability, longevity, safety, crashworthiness, security, alignment, vibration damping, stability, and user convenience. Automotive designers and engineers carefully consider these aspects to ensure robust and reliable mountings that meet the demanding requirements of various vehicle applications.

Finally, we'll thicken the Inner Panel in the required direction which is towards the Class A Surface by 0.75mm. 

 

Next, we're going to work on the Upper and Lower Panel and perform the Hemming Operation with respect to the Inner Panel as well. 

 

REINFORCEMENTS FOR MOUNTINGS:

 

1. HINGE REINFORCEMENT:

 

 

2. GAS STAY REINFORCEMENT:

 

 

3. WIPER MOTOR REINFORCEMENT: 

 

4. LATCH  & STRICKER REINFORCEMENT:

 

POSSIBLE HINGE AXIS:

 

In the case of a backdoor, the hinge axis plays a crucial role in providing smooth and controlled movement during the opening and closing of the door.

Let's explore the use and significance of the Hinge Axis in detail:

 

1. Definition of Hinge Axis:

The hinge axis refers to the imaginary line around which the door rotates or pivots during its movement. It is the axis of rotation for the door. In the case of a backdoor, the hinge axis is typically located on one side of the door, where the hinges are attached.

 

2. Smooth and Controlled Movement:

The primary purpose of the hinge axis is to facilitate smooth and controlled movement of the backdoor. As the door swings open or closed, it rotates around the hinge axis, ensuring a predictable and controlled motion. This allows for easy access to the vehicle's cargo area or storage compartment.

 

3. Proper Door Alignment:

The hinge axis helps maintain proper alignment of the backdoor with the vehicle body. It ensures that the door opens and closes in a straight and consistent manner, eliminating any misalignment or binding. This is crucial for proper sealing, preventing water or air leakage, and ensuring optimal functionality and aesthetics.

 

4. Load Distribution:

The hinge axis also plays a role in distributing the load or weight of the backdoor evenly. As the door swings open, the weight of the door is transferred through the hinge axis to the vehicle structure. A well-designed hinge axis helps prevent excessive stress or strain on the hinges, door structure, and surrounding components. It ensures that the door operates smoothly and without any undue stress on the system.

 

5. Safety Considerations:

The hinge axis is essential for ensuring the safety of the backdoor operation. It allows for controlled movement, preventing sudden or unexpected door movement, which could pose a risk to occupants or nearby objects. The hinge axis enables the door to open and close within a safe range of motion, avoiding any potential accidents or injuries.

 

6. Design Flexibility:

The location and orientation of the hinge axis can influence the design and functionality of the backdoor. Designers can optimize the placement of the hinge axis to achieve specific goals, such as maximizing cargo space, improving access, or enhancing aesthetics. The hinge axis provides flexibility in determining the swing arc and positioning of the backdoor, catering to various vehicle designs and user requirements.

 

In summary, the hinge axis is essential in the case of a backdoor to enable smooth and controlled movement, maintain proper alignment, distribute the load evenly, ensure safety, and provide design flexibility. It serves as the axis of rotation for the door, allowing for predictable and controlled motion. By considering the hinge axis in backdoor design, manufacturers can achieve functional, safe, and aesthetically pleasing door systems.

 

A. UPPER PANEL:

 

HEMMING PROCESS FOR UPPER PANEL: 

The hemming process in sheet metal involves folding and joining two or more layers of metal to create a secure joint. It is widely used in various industries, including automotive, aerospace, and appliance manufacturing. Let's explore why the hemming process is needed and its advantages over other joining processes in greater detail:

HEMMING ROLLER:

 

TYPES OF HEMMING:

 

1. Purpose of Hemming Process:

The primary purpose of hemming is to create a strong, reliable, and aesthetically pleasing joint between sheet metal components. It offers several benefits, including improved structural integrity, enhanced sealing capabilities, increased stiffness, and resistance to vibration and noise. Hemming is commonly employed in applications where a flush, seamless appearance is desired, such as in automotive body panels, doors, and hoods.

 

2. Advantages of Hemming over Other Joining Processes:

2.1. Enhanced Joint Strength:

Hemming provides a robust joint by folding one sheet over another, creating a double-layered overlap. This overlap significantly increases the strength and rigidity of the joint compared to other joining techniques, such as spot welding or adhesive bonding.

 

2.2. Improved Sealing Capabilities:

Hemming creates a tight seal between the joined sheets, making it suitable for applications where sealing against moisture, dust, or air is essential. The folded edge acts as a barrier, preventing ingress or egress of substances, enhancing weather resistance, and improving overall product performance.

 

2.3. Increased Stiffness and Rigidity:

The folded edge formed during the hemming process adds stiffness and rigidity to the sheet metal component. This increased stiffness improves the overall structural integrity, reducing the likelihood of deformation or failure under load or stress.

 

2.4. Enhanced Aesthetics:

Hemming produces a visually appealing joint with a flush, seamless appearance. This makes it particularly suitable for applications where aesthetics are important, such as automotive body panels or visible parts in consumer electronics. The absence of visible fasteners or welds contributes to a clean and finished look.

 

2.5. Compatibility with Thin and Lightweight Materials:

Hemming is well-suited for joining thin and lightweight sheet metal materials, such as aluminium or high-strength steel. It does not require additional materials like adhesives or rivets, minimizing weight and simplifying the manufacturing process.

 

3. Hemming Process Variants:

There are different variations of the hemming process, including conventional hemming, roll hemming, and power hemming. Each variant has its own advantages and considerations, depending on factors such as material thickness, production volume, equipment availability, and desired joint characteristics.

In summary, the hemming process in sheet metal is needed to create strong, sealed, and aesthetically pleasing joints. It offers advantages over other joining processes, including enhanced joint strength, improved sealing capabilities, increased stiffness, and superior aesthetics. Hemming is a versatile technique compatible with thin and lightweight materials, making it a preferred choice in various industries. The specific variant of the hemming process chosen depends on factors such as material thickness, production volume, and desired joint characteristics.

 

1. We'll offset the Class A Surface by 2.65mm and create a 2mm surface along the edges to create the flange for hemming using various options such as 'Offset Curve in Face', 'Spline', 'Trim Sheet', etc as shown below:

  

 

2. There are two methods using which we can create curves region of the Hemming Process.

A) Law Extension Method

B) 'Swept Curve' and 'Through Curve Mesh' using Bridge Curves

We are going to use the second method for the Upper Panel and the First Method for the Lower Panel. 

We'll create Bridge Curves that can be used eventually to create surfaces along the edge of the Class A Surface and the Offsetted Flange's Surface as shown below:

 

3. Using Swept Curve & Through Curve Mesh options we're going to create all of the required surfaces as shown below:

 

4. After creating the necessary surfaces, we will merge them together and extend them slightly in the desired direction. This extension allows us to trim the surfaces accurately with respect to a plane. By doing so, when we mirror this geometry on the opposite side of the plane, we ensure a seamless connection without any gaps or boundaries between the surfaces. This seamless connection enables us to obtain the best possible surface that can be thickened along the intended direction.

 

 

5. The final step before thickening the surface is to provide them relief at the required locations to ensure that unnecessary stress concentrations don't occur after or during the hemming process. 

 

HEM RELIEF:

Hem relief is provided in sheet metal before performing the hemming operation for several reasons. Let's delve into the significance of hem relief in detail:

1. Material Stretching and Springback Compensation:

During the hemming process, the sheet metal undergoes deformation and stretching as it is folded over itself. This stretching can cause the material to elongate and result in spring back, where the material tries to return to its original shape. Hem relief compensates for this stretching and spring back by providing additional material in the folded area. This ensures that the final hemmed part has the desired dimensions and shape after the spring-back effect.

 

2. Preventing Wrinkling and Buckling:

Without hem relief, the excess material in the folded area can lead to wrinkling or buckling, especially in cases where the material is thicker or has low ductility. Wrinkling occurs when the excess material is not accommodated properly, resulting in the formation of unwanted folds or creases. Buckling refers to the instability of the material, causing it to buckle or deform under compression. Hem relief helps prevent these issues by allowing the excess material to be distributed evenly and smoothly during the folding process.

 

3. Ensuring Proper Hem Formation:

Hem relief plays a crucial role in achieving a well-formed and consistent hem. By providing additional material in the folded area, hem relief allows for proper folding and a uniform distribution of stress. This ensures that the hem is tightly sealed, providing a secure joint with improved strength and integrity.

 

4. Minimizing Surface Imperfections:

Hem relief helps minimize surface imperfections that can occur during the hemming process, such as scratches, cracks, or distortions. By accommodating the excess material, hem relief reduces the likelihood of these imperfections, resulting in a smoother and aesthetically pleasing surface finish.

 

5. Enhancing Manufacturing Efficiency:

Including hem relief in the design and manufacturing process streamlines the hemming operation. It reduces the chances of rework or scrap due to incorrect dimensions or shapes caused by material stretching and spring back. By anticipating and accommodating these factors, hem relief improves manufacturing efficiency, reducing overall production time and costs.

 

In summary, hem relief is provided in sheet metal before performing the hemming operation to compensate for material stretching and spring back, prevent wrinkling and buckling, ensure proper hem formation, minimize surface imperfections, and enhance manufacturing efficiency. By considering these factors, designers and engineers can achieve high-quality, dimensionally accurate, and visually appealing hems in sheet metal components.

 

 

Next, we'll use the 'Thicken' option to thicken the part by 0.75mm and view the hemmed region using 'Clip Section View' as shown below:

1. CLIP SECTION VIEW AT THE CENTER:

 

2. CLIP SECTION VIEW NEAR THE CORNER SHOWCASING THE HEM RELIEF:

 

3. CLIP SECTION VIEW AT MASTIC REGION:

 

 

B. LOWER PANEL:

 

HEMMING PROCESS FOR THE LOWER PANEL:

First, we're going to get rid of the excess surface using the 'Offset Curve in Face' and 'Trim Sheet' option as shown below:

 

Then, we're going to use the 'Extend Sheet' option to extend the sheet evenly as shown below:

 

We're going to use the 'Offset Curve in Face' option to create the Hemming Flange excluding the curved area as shown below:

 

After that, we're going to offset this trimmed surface by 2.65mm according to our design considerations as shown below:

 

Now, we're going to use the 'Law Extension' option with respect to the faces of these surfaces as shown below:

 

Finally, we're going to use the 'Face Blend' option with the Three-face Method to create the blended surface between these surfaces as shown below:

 

HEM RELIEF:

 

Finally,  we're going to thicken it in the required direction as shown below:

1. Thickened Inner Panel:

 

2. Clip Section View of the Lower Panel with Hem Relief viewed with respect to the Inner Panel:

 

3. Clip Section View of the Upper and Lower Panel:

They're going to be joined together by spot welding and hence there are no gaps between these surfaces.

 

 

DRAFT ANALYSIS:

Draft analysis is crucial for sheet metal components due to the manufacturing process involved, which typically includes forming or bending the metal sheet into the desired shape. The minimum draft angle requirement of 7 degrees for sheet metal components is significant for several reasons. Let's explore the importance of draft analysis and the reasons behind the specific minimum draft angle in greater detail:

 

1. Ease of Manufacturing:

Draft angles facilitate the smooth and efficient manufacturing of sheet metal components. When a sheet metal part is formed or bent, material flow occurs. The material needs to flow smoothly without excessive resistance or deformation. A proper draft angle ensures that the material can easily flow and conform to the desired shape during the forming process. This reduces the risk of wrinkling, tearing, or other defects that could compromise the quality and functionality of the component.

 

2. Preventing Sticking and Binding:

Sheet metal components with insufficient draft angles may experience sticking or binding during the forming process. Sticking occurs when the material adheres to the forming tool or dies, making it difficult to remove the part without damage. Binding happens when the material gets trapped or wedged between the forming tool and the part, resulting in deformation or distortion. Adequate draft angles minimize the likelihood of sticking or binding, allowing for smooth and successful forming operations.

 

3. Reducing Friction and Wear:

Draft angles help reduce friction between the sheet metal and the forming tooling. Friction can cause excessive heat generation, wear on the tooling, and damage to the sheet metal surface. By incorporating the minimum draft angle, the contact between the forming tool and the sheet metal is optimized, reducing friction and minimizing wear. This leads to longer tool life and improved manufacturing efficiency.

 

4. Enhancing Material Thickness Consistency:

The minimum draft angle requirement ensures consistent material thickness throughout the formed part. Insufficient draft angles can cause thinning or thickening of the material in certain areas, leading to dimensional inaccuracies and compromised structural integrity. By adhering to the minimum draft angle, material thickness consistency is maintained, ensuring the desired functionality and performance of the sheet metal component.

 

5. Consideration of Material Properties:

Different sheet metal materials have varying degrees of ductility and elasticity. The minimum draft angle requirement takes into account the material's properties to ensure successful forming without causing excessive stress, deformation, or failure. The 7-degree minimum draft angle is a general guideline that is suitable for a wide range of sheet metal materials, striking a balance between ease of manufacturing and maintaining structural integrity.

 

6. Design for Manufacturability:

Draft analysis and adhering to the minimum draft angle requirement are essential aspects of design for manufacturability (DFM). By considering manufacturing constraints early in the design process, designers can optimize the manufacturability of sheet metal components, reduce production costs, and minimize the likelihood of rework or scrap.

 

In summary, draft analysis is important for sheet metal components to ensure ease of manufacturing, prevent sticking and binding, reduce friction and wear, enhance material thickness consistency, and consider material properties. The specific minimum draft angle requirement of 7 degrees is a guideline that strikes a balance between manufacturability and maintaining structural integrity. Adhering to this minimum draft angle helps achieve high-quality sheet metal components that meet functional and dimensional requirements.

 

DRAFT ANALYSIS ON THE UPPER PANEL:

1. FRONT VIEW:

 

2. REAR VIEW:

 

 

3. ISOMETRIC VIEW:

 

DRAFT ANALYSIS ON THE LOWER PANEL:

1. FRONT VIEW:

 

2. REAR VIEW:

 

3. ISOMETRIC VIEW:

 

DRAFT ANALYSIS ON THE INNER PANEL:

1. FRONT VIEW:

 

2. REAR VIEW:

 

3. ISOMETRIC VIEW:

 

 

SINCE THE SIZE OF MY FILES EXCEEDS THE 20MB UPLOAD LIMIT I AM PROVIDING A GOOGLE DRIVE LINK FOR MY FINAL SUBMISSION FILES.

LINK FOR THE ZIP FILE: https://drive.google.com/file/d/1khXDDuhsxRy6rWErws-6IwTTr6errKWB/view?usp=sharing

LINK FOR THE ENTIRE FOLDER CONSISTING OF THE ZIP FILE AS WELL: 

https://drive.google.com/drive/folders/1rQx6porjJXNKXX5lP_5Oqx7sdtS9diII?usp=sharing