What is pre-bending in plate rolling?

1. The definition and core role of the pre-bending

pre-bending is a plate rolling machine for the ends of the local bending process. When the plate is directly rolled round, the ends will not be fully squeezed by the rollers and the formation of straight sections (commonly known as “straight edge”), affecting the closed precision of the finished cylinder. Pre-bending applies an initial bending of 15°-30° to both ends of the plate in advance through a special mold or adjusting the position of the rollers (refer to the Metal Forming Process Handbook), to ensure that the overall curvature of the subsequent rolled round is uniform.

Its core roles include:

(1) Eliminating straight edge defects and improving the geometric accuracy of the cylinder;

(3) Reducing the workload of the subsequent proof-rounding process;

(4) to avoid cracks in the material due to excessive stretching.

2. Principle of the pre-bending function of the coiler

The pre-bending function of the coiler refers to a certain degree of pre-bending curvature of the plate by the coiler before coiling, so that the bending and deformation of the plate produced in the process of coiling can be effectively controlled. The core principle of the technology is to use the curved rolls of the coiler to exert a certain bending force, thereby reducing the stress and deformation of the plate.

3. The common realization of the pre-bending of the coiler and technology comparison

(1) mold pre-bending

The use of curved molds to press the ends of the plate, applicable to the thickness of ≤ 20mm of steel plate (data source: JIS B 6803 standard). Its main advantage is low cost, but lower efficiency and the need to manually adjust the position of the mold, so it is suitable for small-scale production.

(2) Pre-bending by three-roll coiler

Pre-bending is accomplished in stages by adjusting the amount of downward pressure on the upper roll (usually 1.5-2 times the thickness of the plate) and the tilt angle of the side rolls. Modern CNC plate rolling machine can automatically calculate the parameters, accuracy of ± 0.1 °, greatly improving the processing efficiency and accuracy.

(3) four-roller coiler pre-bending

The use of additional support rolls on the end of the plate pre-bending, suitable for heavy plates with a thickness of > 50mm, the pre-bending radius can be controlled in the range of R50-R500mm (according to DIN 8528 standards), can accurately meet the pre-bending requirements of different thicknesses and needs of the plate. Four-roller plate rolling machine is widely used in large pressure vessels, ship hulls and heavy steel structure processing.

4. The role of the pre-bending function of the coiler

The pre-bending function of the coiler can not only improve the processing accuracy, eliminate straight edge defects, but also effectively improve production efficiency and product quality. Specific role as follows.

-Improve processing accuracy: through the pre-bending technology, the geometry of the plate can be optimized, the finished product is more accurate, in line with the design requirements.

Reduce the burden of subsequent processes: pre-bending technology reduces the complexity of subsequent rounding operations, reducing labor hours and processing costs.

Enhance product stability: pre-bending technology can control the stress distribution of the plate in the rolling process, to avoid excessive deformation, improve product stability.

5.Application Scenarios of Pre-bending Function of Coiling Machine

The pre-bending function of coiling machine is widely used in many industries and fields such as iron and steel, machinery, shipbuilding, chemical industry, automobile and so on. In the manufacture of large pressure vessels, tanks, pipelines, hulls and other important equipment and components, the use of coiling machine pre-bending technology can improve the precision and stability of the product, to protect the quality and safety of the product.

6. The development prospects of the pre-bending function of the coiler

With the development of industrial automation and intelligence, the pre-bending function of the coiler is gradually realizing digitalization, intelligence and automation. Through the introduction of artificial intelligence, machine learning, adaptive control and other technical means, the pre-bending function of the coiler will further improve processing accuracy, energy saving, cost reduction, and promote the sustainable development of industrial production.

The pre-bending function of the coiler is a commonly used plate pretreatment technology with important application and development value. Various industries and fields should actively adopt this technology, continuous innovation and breakthroughs, promote the digitalization, intelligence and automation of the pre-bending function of the coiler, and promote the high quality and sustainable development of industrial production.