Conformação a frio de aço inoxidável: um guia abrangente

Stainless Steel Cold Forming: A Comprehensive Guide

Metal processing can be broadly categorized into two types: cold and hot processing.

Hot processing refers to processing materials after they are heated, such as hot rolling, while cold processing involves processing metal at normal temperatures, such as turning, milling, chipping and grinding.

Cold forming is also part of cold processing. Although it has been around for a long time, it is still largely an empirical discipline.

Most cold forming techniques are suitable for all metals except stainless steel, as stainless steel has greater strength and hardenability. Furthermore, stainless steel parts after cold processing serve both functional and ornamental purposes, making it crucial to protect their surface from damage and rust.

Therefore, special techniques must be employed for the cold processing and production of stainless steel.

Common cold forming methods for stainless steel

In the stainless steel forming process, two main technologies are used: cold rolling and hot rolling. In the field of cold processing, there are several methods for you to choose from.

Here is a brief overview of some of the common cold forming techniques for stainless steel:

(1) Cold Bending Forming

Cold Bending Forming

Curved plates are commonly used to produce a variety of thin plate cylinders or cylinder segments.

The traditional rolling mill has a pair of adjustable rollers that can be adjusted according to the thickness of the steel plate. The third roller, known as the bending roller, controls the diameter of the cylinder body.

There is also a variant of this machine that uses three rollers arranged in a pagoda shape. The lower roller is the driving roller and the upper roller rotates due to the friction between it and the workpiece. The diameter of the lower roller is normally half the diameter of the upper roller.

The minimum diameter of the cylinder produced by these two types of equipment is the diameter of the upper roll plus 50mm, while the maximum diameter depends on the size of the material, the rigidity of the machine and the parts. In certain cases, the cylinder may need to be supported by structures.

In reality, different products may require a combination of several methods or different processing techniques to achieve the desired quality. Therefore, it is important to have a good knowledge of stainless steel cold forming methods to use them effectively.

Common problems and treatment measures in the stainless steel cold forming process

(1) The presence of flaws such as dirt, scratches, holes, pits or double skin on the surface of roughcast materials can be aggravated during the cold forming process, leading to a decrease in the quality of the finished product. Therefore, it is important to thoroughly inspect the surface condition of sheet metal materials before forming to ensure they are clean and free from defects.

(2) The formation of dirt, rust, holes and scratches on the surface of the workpiece may occur when the forming mold and working platform are dirty and the metal fragments are not cleaned in a timely manner. To avoid this, it is important to regularly polish the mold to keep it clean and to keep the processing equipment and workshop clean.

(3) Some forming techniques involve sliding contact between the metal, which can damage the stainless steel's passivation coating and result in cold welding between the stainless steel surface and the tool. This can cause serious scratches on the stainless steel surface if the weld breaks during sliding. To avoid this, it is important to keep the molding equipment in good condition and have qualified and cautious operators to avoid material slippage.

(4) Stainless steel has high strength, and austenitic stainless steel has significant cold hardenability. If the deformation is too large during the cold forming process, it may lead to part fracture or damage to the mold and machine equipment. To avoid this, it is important to test the stiffness of the part and maintain a reasonable amount of deformation, while ensuring production efficiency and product quality.

(5) After cold forming, the surface passivation coating of stainless steel may be damaged and contaminated with stamping oil, mold debris and other metals, which can easily lead to corrosion. To ensure a finished part with good stainless properties and a smooth finish, it is important to clean oil stains and passivate the process and, if possible, protect the surface of the part with a plastic film.

As the demand for stainless steel increases, the use of cold forming technologies for stainless steel is becoming more widespread. It is important to choose the appropriate forming technique based on product characteristics, maximize production efficiency and reduce production costs to provide consumers with affordable and high-quality stainless steel products.

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