Types of Tube Bending

Rotary Draw Mandrel Tube Bending

Rotary draw tube bending is a precise and versatile method used to bend tubes and pipes. Here’s a breakdown of how it works and its key components:

How It Works

In rotary draw bending, the tube is clamped to a bend die and drawn around it to form the bend. The process involves several key tools and steps:

• Bend Die: This is the primary tool that determines the bend radius. The tube is wrapped around this die.
• Clamp Die: This die holds the tube in place against the bend die.
• Pressure Die: It applies pressure to the tube, ensuring it stays in contact with the bend die during the bending process.
• Mandrel: Inserted into the tube, it supports the tube internally to prevent collapse and maintain shape. This is used for thin wall tube.
• Wiper Die: Positioned at the inside radius of the bend, it prevents wrinkling of the tube.

Process Steps

• Clamping: The tube is clamped to the bend die using the clamp die.
• Bending: The bend die rotates, drawing the tube around it while the pressure die maintains pressure.
• Support: The mandrel and wiper die support the tube to prevent defects like wrinkling or flattening.

Advantages

• Precision: Rotary draw bending allows for tight radii and complex shapes with high accuracy.
• Versatility: Suitable for various materials, including steel, aluminum, and copper.
• Quality: Produces smooth, consistent bends without significant deformation.

Limitations

Rotary draw bending is limited to smaller radius bends, typically under 12″ center line radius. Larger radius bends are made using roll forming, also referred to as profile bending.

This method is widely used in industries such as farm equipment, medical carts, handrails and more due to its ability to produce high-quality bends efficiently.

 

Tube Roll Bending (also known as Profile Bending):

• Tube roll bending is a process used to form tubes or pipes into curves, arcs, or circular shapes through the use of three rollers. It’s widely used for bending large-diameter tubes or pipes, particularly in industries such as construction, automotive, and heavy equipment manufacturing. The process is known for producing smooth and consistent bends without distorting the tube’s integrity.
• Setup:
  • A tube is placed between three rollers (usually in a triangular arrangement). These rollers apply pressure to the tube, gradually bending it into the desired shape. The rollers can be adjusted to control the amount of curvature, and the tube is usually fed through the machine multiple times to achieve the desired bend radius.

• Roller Configuration:
  • Top Roller: This roller is adjustable and applies downward force on the tube.
  • Bottom Rollers: The bottom rollers are positioned symmetrically on either side of the top roller and are responsible for guiding the tube through the machine and applying sideward pressure.

• Bending Process:
  • The tube is fed into the machine and positioned so that the rollers press against it from different angles.
    • As the tube moves through the machine, the rollers gradually apply pressure, and the tube begins to bend around the rollers.
    • This process can be repeated multiple times for more complex curves, allowing for a high degree of control over the bend radius and the tube’s final shape.

• Bend Radius:
  • Tube roll bending allows for creating large, gentle bends with a relatively large radius. The bend radius depends on the tube’s material, thickness, and diameter, as well as the settings of the rollers.

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Advantages of Tube Roll Bending:

• Versatility: Suitable for a wide range of materials and tube sizes, including mild steel, stainless steel, aluminum, and copper.
• No Need for Fittings: Because the tubes are bent in a continuous curve, there’s no need for additional fittings or joints, which can improve the overall strength and appearance.
• Large-Diameter Tubing: Ideal for bending large-diameter tubes that might be difficult to bend using other methods.
• Precision: When used correctly, tube roll bending offers consistent bends with precise radii and angles.
• Cost-Effective: Since it doesn’t require specialized dies or tooling like other methods, roll bending can be more cost-effective for certain applications.

Applications of Tube Roll Bending:

• Automotive Industry: Creating roll cages, chassis components, and exhaust systems.
• Furniture: Bending large-diameter tubes for curved furniture pieces like chairs and tables.
• Construction: Making curved structural elements such as pipes for handrails, fences, or architectural features.
• Industrial Equipment: Forming tubes for machinery or pipeline systems.

Limitations:

• Tight Radius Limitations: Tube roll bending is not ideal for very tight or small-radius bends, as it typically works best for larger-radius curves.
• Material Restrictions: Some materials, especially those that are very thick or hard, can be more difficult to bend using this method without causing deformation.

 

Compression Bending (also known as Press Bending)

• Process: In compression bending, the tube is pressed against a die while a bending force is applied to compress and bend the tube into the desired shape. This method is typically used for larger tubes with low to medium bend radii.
• Key Features:
  
  • Simple and efficient for large-diameter tubes.
  • Works well for producing gentle bends.
  • The tube can be bent into various shapes, including curves, angles, and compound bends.
• Applications: Automotive and heavy equipment components, structural supports, and curved piping.