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Essential Pre-Bending Techniques in Plate Rolling

Plate rolling stands as a fundamental process in the metal fabrication industry, serving the purpose of transforming various sheet metals, including stainless steel, aluminum, and other alloys, into a wide array of shapes. Plate bending and rolling technology plays a ubiquitous role across various industries, ranging from sewage systems to the construction of substantial machinery, showcasing its widespread application in diverse sectors. This intricate procedure relies on plate rolling machines, also known as roll bending machines, which employ diverse mechanisms like mechanical, hydraulic, or electrical systems to execute shaping operations in accordance with specific rolling capacity requirements.

What is plate rolling

4-Roll Bending Machine: From Pre-pinching and Pre-bending to the end of the Rolling Work

Plate rolling refers to a manufacturing technique employed to shape different types of sheet metals, primarily stainless steel, aluminum, and steel, into an assortment of forms such as circular, conical, round, or other specified shapes.

Plate rolling machines, commonly known as “plate rollers” or “roll bending machines,” are instrumental in transforming these materials by exerting force through their rollers. These rollers are propelled by mechanical, hydraulic, or electrical systems, effectively imparting the desired shapes to the sheet metals. The selection of a plate rolling machine is contingent upon the required rolling capacity necessary for a particular application or project.

The capacity of a plate rolling machine is determined based on the force and capability it can exert during the rolling process.

Pre-pinching and Pre-bending


Pre-pinching constitutes the initial bending phase of a metal plate by tightly securing it between two rolls within a plate bending machine. This preliminary manipulation is imperative for manufacturers seeking the flattest possible end result from the metal plate.

3-Roll Bending Machine: From Pre-pinching and Pre-bending to the end of the Rolling Work

When embarking on the bending or rolling of a metal plate, several critical parameters demand consideration, including the desired bending or rolling angle, waste reduction strategies, optimization of machine efficiency, and other pertinent factors.

The primary objective of the pre-pinching or pre-bending process lies in establishing a connection between the two ends of the metal plate. By initiating the bending process at the outset, the plate’s pre-bent end achieves an optimal level of flatness, a crucial aspect in the manufacturing process.


pre-bending principle of prt plate rolling machine

Pre-bending involves securely gripping sheet metal between multiple rolls and applying pressure to create an initial bend. As the rolls rotate within the plate rolling machine, the sheet metal passes through these rolls. Upon completing a 360-degree rolling cycle, the material’s pre-bent end facilitates seamless connection between the two ends, a result achieved through the efficacy of the pre-bending process.

Pre-bending, a pivotal component within the realm of plate rolling, embodies the practice of securely positioning sheet metal amid multiple rolls to initiate its initial curvature. These rolls, actuated by the rotation mechanism within plate rolling machines, instigate the bending process, allowing the material to take on its preliminary curve. This initial curvature, when executed correctly, facilitates a seamless connection between both ends of the metal sheet after the rolling process concludes.

The concept of pre-bending is rooted in the necessity to establish a foundational curvature in the material before commencing the full rolling operation. By initiating the initial curve, this preparatory step ensures a smoother and more cohesive result at the conclusion of the rolling process. It sets the stage for the desired shape to be achieved with precision and accuracy, ensuring that the material retains its intended form and structural integrity throughout the rolling procedure.

Furthermore, pre-bending serves as an essential precursor in achieving the desired curvature, uniformity, and precision in the final product. It contributes significantly to the efficiency of the overall rolling process by establishing a solid foundation upon which subsequent rolling procedures can build. The successful execution of pre-bending ensures that the material’s ends meet seamlessly, minimizing the need for additional adjustments or corrective measures post-rolling, thus optimizing the fabrication process as a whole.

Understanding the Disparity Between Pre-bending and Rolling Capacities in Plate Rolling Machines

Essential Pre-Bending Techniques in Plate Rolling
Essential Pre-Bending Techniques in Plate Rolling

Plate rolling machines often have a pre-bending capacity set at approximately 80% of their rated rolling capacity. This discrepancy stems from the pre-bending process itself, primarily aimed at reducing the unbent flat edge at the leading and trailing edges of a sheet during plate rolling. Physically, a sheet cannot be bent entirely to the edge, leaving behind the unbent flat, which typically measures 1.5 times the material thickness and can range from 2.5 to 3.5 times for thicker plates. The pre-bending operation, aimed at minimizing this unbent flat, demands the most power, thus resulting in lower pre-bending ratings compared to the rolling capacities of plate rolling machines.

4 Key Reasons for Pre-Bending in Plate Rolling

Pre-bending, an integral aspect of plate rolling, holds immense significance in metal fabrication processes for various reasons:

  1. Uniform Surface Bending: Pre-bending ensures the creation of properly rolled metal plates with a smooth and uniformly bent surface. This precision is vital when engineers specify specific shapes and sizes for metal structures.
  2. Reduction of Wastage: Optimal structural formation provided by pre-bending allows plates to connect both ends with near-perfect angles. This minimizes waste, ensuring maximum efficiency and resource utilization.
  3. Elimination of Trimming Requirements: Pre-bending aligns both ends of a rolled plate almost perfectly, eliminating the need for extra trimming. This saves resources and guarantees the efficiency of the rolled metal plate.
  4. Time Efficiency: In high-volume production environments, time is money. Pre-bending allows for faster shaping of metal plates, reducing the operating time per sheet on a plate rolling machine. This increased efficiency leads to rolling more parts within less time.

The pre-bending process also contributes to creating smoothly bent surfaces with uniform curvature and thickness. By initiating the initial bend, pre-bending ensures that the material rolls correctly, achieving the intended results accurately.

Employing skilled plate rolling machine operators during the pre-bending process further enhances its effectiveness, minimizing waste and optimizing resource utilization. Hence, pre-bending emerges as a critical step in plate rolling, offering numerous advantages to fabrication shops and operations worldwide.

Mastering Pre-Pinching and Pre-Bending Techniques in Plate Rolling

The pre-pinching or pre-bending process, an integral stage in plate bending or rolling, is facilitated by utilizing the plate bending or rolling machine itself. This operation can be performed on various plate bending or rolling machines, including 3-roll or 4-roll plate bending machines.

To initiate the pre-bending procedure:

  1. Plate Preparation: Start by placing the metal plate securely on the conveyor or support table to prevent undesired bending or breaking caused by the plate’s weight or length.
  2. Positioning in the Machine: Guide the plate between the top roll and the bottom rolls of the plate bending or rolling machine. Ensure the plate end is firmly positioned within these rolls.
  3. Executing the Bend: Apply pressure to the plate between the rolls, initiating a 360-degree bending process. This action effectively pre-pinches or pre-rolls the plate, creating the initial bend.

Upon completion of the pre-bending process, you’ll have the pre-pinched or pre-rolled end of the plate. Subsequently, you can proceed with the subsequent bending or rolling of the plate to achieve the desired shape.

A sequential breakdown of the pre-pinching or pre-bending process is as follows:

  • Place the plate onto the support table or conveyor.
  • Securely position the plate’s end between the top roll and bottom rolls of the plate bending or rolling machine.
  • Under the guidance of an experienced operator, initiate the machine to perform a 360-degree bending on the metal plate, ensuring the desired bent shape is achieved.

This systematic approach ensures the successful pre-bending or pre-pinching of the metal plate, setting the stage for further shaping to attain the desired and necessary configuration.


In essence, the practice of pre-bending in plate rolling stands as a pivotal technique within the metal fabrication process. It serves as a foundational step, crucial for achieving precise shapes and ensuring minimal waste in the manufacturing of diverse metal components.

Mastering the art of pre-pinching and pre-bending techniques plays a significant role in optimizing the fabrication process, reducing material wastage, and ultimately enhancing the quality of the end products. Skilled operators, coupled with the capabilities of plate rolling machines, form the cornerstone for successful implementation of these techniques.

The importance of pre-bending becomes evident in its contribution to the efficiency of plate rolling, guaranteeing smoother surfaces, uniform curvatures, and precision in shaping metal components. This foundational process remains indispensable across industries, underscoring its vital role in creating structurally sound and accurately shaped metal products.