What Is The Difference Between Torsion and Bending in Metal Bending Machine?

In the field of metal processing, the metal bending machine is a core piece of equipment, tasked with the crucial mission of transforming metal raw materials into products of various shapes and functions. From basic metal brackets to complex components in high – end machinery, their formation relies on metal bending machines.

Torsion and bending are two fundamental operations in metal bending. Although they seem similar as both involve metal deformation, they actually differ in many aspects. Clearly understanding these differences is of utmost importance to metal processing practitioners, engineers, and manufacturers. This not only optimizes the technological process but also ensures the production of high – quality metal products. This article will conduct an in – depth analysis of the differences between torsion and bending in metal bending machines, covering aspects such as principles, material compatibility, equipment characteristics, application scenarios, and operation key points.

A. Torsion Principle

B. Bending Principle

A. Responses of Different Materials to Torsion

1. Carbon Steel
   Carbon steel is a commonly used metal in various industries. When subjected to torsion in a metal bending machine, its performance depends on the carbon content. Low – carbon steel, with its relatively soft and ductile nature, can withstand a certain degree of torsion before failure. The low carbon content allows the metal atoms to slide past each other more easily during the torsion process. However, if the torque is too high, it will eventually reach its yield point and start to deform plastically. On the other hand, high – carbon steel is harder and more brittle. It has a lower tolerance for torsion, and excessive torque can cause it to crack or fracture quite quickly.
2. Stainless Steel
   Stainless steel is well – known for its corrosion – resistance properties and also exhibits unique behaviors under torsion. Austenitic stainless steel, the most common type, has good ductility and toughness, enabling it to better adapt to the applied torque during the torsion process. However, the presence of alloying elements such as chromium and nickel can also affect the material’s response. These elements can increase the strength of the steel, making it more resistant to torsion. But at the same time, if not properly processed, they can make the material more sensitive to stress – corrosion cracking.

B. Responses of Different Materials to Bending

1. Minimum Bending Radius
   When considering metal bending, the minimum bending radius is an important parameter. Different materials have different minimum bending radii. For example, soft metals like aluminum alloys usually have a lower minimum bending radius compared to hard metals such as high – carbon steel. This means that aluminum alloys can be bent into sharper curves without cracking. The minimum bending radius also depends on the thickness of the metal. Thicker metals generally require a larger minimum bending radius.
2. Stress Distribution Induced by Bending
   After bending, the stress distribution within the metal is non – uniform. As mentioned before, there is a neutral axis where the stress is zero. The material on the outer side of the bend is in a tensile state, while the material on the inner side is in a compressive state. The magnitude of these stresses depends on the material’s properties, the bending radius, and the thickness of the metal. For materials with a high yield strength, such as some high – strength steels, the stress levels during bending can be very high. This requires careful consideration during the bending process to avoid over – stressing the metal and causing premature failure.

When choosing a bending process for a specific material, its material properties and minimum bending radius must be taken into account. For example, if a metal has a high requirement for the minimum bending radius, a more gentle bending process may be needed. If the material is prone to stress – corrosion cracking, special attention should be paid to the stress levels during the bending process.

A. Characteristics of Torsion Equipment

• Powerful Torque Output: It requires a high – torque motor or a specially designed transmission system to provide the rotational force for twisting the metal. Moreover, the torque output needs to be adjustable to adapt to different metal materials and processing requirements.
• Robust and Rigid Structure: The overall structure is extremely robust and rigid. This is to withstand high – torque forces, avoid significant deformation, and ensure accurate and consistent torsion results.
• Unique Die Design: Torsion dies are different from common bending dies. They are designed to firmly clamp the metal along its length to facilitate rotation. For example, a die for twisting metal rods may have a circular opening with ridges inside that match the outer surface of the rod. With special grooves or teeth, it can hold the metal firmly. Such dies need to be able to transmit torque efficiently and ensure smooth rotation. The materials used for these dies are generally high – strength alloys to withstand the wear and tear caused by repeated torsion.

B. Characteristics of Bending Equipment

• Structure of the Press Brake Machine
  
  The press brake machine is a common metal bending device, mainly composed of an upper beam and a lower bed. The upper beam is equipped with an adjustable upper die, and the lower bed has a fixed or adjustable lower die. The upper beam moves up and down through a hydraulic or mechanical system to apply the bending force. Its hydraulic system can provide a stable and controllable force, and will adjust the output force according to the thickness and material of the metal. For instance, bending a thick steel plate requires a greater force than bending a thin aluminum plate.
• Pressure and Stroke Control

1. Pressure Control: In a press brake machine, precise pressure control is crucial for accurate bending. The pressure needs to be precisely adjusted according to the metal material and the desired bending angle. If the pressure is too low, the metal may not be bent to the required degree. If the pressure is too high, the metal may crack or deform.
2. Stroke Adjustment: The stroke of the upper beam determines the bending depth and needs to be set carefully. For example, during V – shaped bending, the stroke should be adjusted so that the punch reaches the appropriate depth within the V – shaped die. To ensure bending accuracy, most modern press brake machines are equipped with advanced control systems that can monitor and adjust the pressure and stroke in real – time based on parameters such as the material type, thickness, and desired bending angle.

There are significant differences between torsion and bending in metal bending machines in terms of principles, applicable materials, equipment, applications, and operation key points. Looking ahead, technological development will drive their progress. In the field of torsion, there will be more intelligent torque control and wear – resistant die materials. Regarding bending, automation and precision will be enhanced, enabling automatic detection and parameter adjustment. The integration of artificial intelligence and machine learning can also analyze data, predict problems, reduce waste and production time, and contribute to the development of the industry.