How To Produce Small-diameter Precision Tube?

Small-diameter precision tube is a high-precision, high-performance steel pipe material, and its manufacturing process involves multiple complex and delicate links. The following is a detailed introduction to its process:

Raw material selection and preparation

The manufacture of small-diameter precision tube starts with high-quality raw materials. These raw materials mainly include high-quality carbon steel pipe, alloy steel pipe or stainless steel pipe, such as No. 10 steel, No. 20 steel, No. 35 steel, No. 45 steel, 16Mn, 27SiMn, etc. These materials have good machinability and mechanical properties, and can meet the needs of different application fields.

In the raw material preparation stage, the raw materials need to be strictly inspected and accepted to ensure that their chemical composition, mechanical properties and surface quality indicators meet production requirements.

Heating process

After the billet is prepared, it enters the heating link. The purpose of heating is to improve the plasticity of the billet, which is convenient for subsequent processing steps such as perforation and rolling. Generally, a ring heating furnace is used to heat the billet. During the heating process, the heating temperature and time must be precisely controlled.

If the heating temperature is too low, the plasticity of the billet is insufficient, and defects such as cracks are easily generated in the process of perforation; if the heating temperature is too high, it may cause problems such as overheating and decarburization of the billet surface, affecting the quality of the steel pipe.

The appropriate heating temperature range for billets of different materials is also different. Usually, the heating temperature of carbon steel billets is around 1100-1250. At the same time, the heating time should be reasonably set in strict accordance with the specifications of the billet and the characteristics of the heating furnace to ensure that the billet is heated evenly as a whole.

Perforation process

Piercing is the key process for processing solid billets into hollow rough tubes. Common perforation methods include oblique rolling perforation and push rolling perforation.

Oblique rolling perforation is widely used. It uses two or three rollers arranged at a certain angle to gradually make the billet hollow during the process of rotation and advancement. During the perforation process, the speed of the rollers, the feed angle and other parameters should be controlled. Too fast speed or too large feed angle can easily lead to uneven wall thickness and poor inner surface quality of the rough tube; too slow speed or too small feed angle will affect production efficiency.

The wall thickness accuracy and inner surface quality of the rough tube after perforation have an important impact on the subsequent processing and final product quality. Therefore, it is necessary to strictly inspect the rough tube after perforation. For the rough tube with too large wall thickness deviation or obvious defects on the inner surface, it is necessary to repair or scrap it.

Cold rolling or cold drawing

Cold rolling and cold drawing are key processes in the production of small-diameter precision steel tubes.

1. Cold rolling

The rough tube is rolled by rollers to make its size more accurate. During the rolling process, parameters such as rolling temperature, rolling speed and rolling force need to be strictly controlled to ensure the quality and accuracy of the steel tube.

2. Cold drawing

At room temperature, the steel tube is drawn through a die to reduce its cross section and increase its length, while significantly improving the dimensional accuracy and surface finish of the steel tube. During the cold drawing process, the metal structure of the steel pipe is refined, and its mechanical properties, such as strength and hardness, are improved.

Subsequent treatment

The steel pipe after cold rolling or cold drawing needs to undergo a series of subsequent treatments to further improve its quality and performance.

1. Pickling and phosphating

The steel pipe after cold drawing and cold rolling is pickled again to remove the film and impurities on the surface of the steel pipe, and then phosphating is performed to form a protective film to improve the corrosion resistance and surface adhesion of the steel pipe.

2. Annealing treatment

The steel pipe is heated and cooled to eliminate the stress caused by cold working, improve the mechanical properties of the steel pipe, and achieve the ideal mechanical properties and grain structure. Sometimes annealing is also performed in a protective atmosphere to keep the steel pipe bright and dimensional accuracy.

3. Cutting and trimming

The annealed steel pipe is cut to the required length, and the end face of the steel pipe is flat, burr-free, and crack-free through trimming.

4. Surface treatment

Including cleaning and removing impurities such as cutting chips to ensure the smoothness and cleanliness of the steel pipe surface.

Quality inspection

Strict quality inspection of steel pipes, including dimensional accuracy, mechanical properties, surface quality and other aspects, to ensure that the various performance indicators of steel pipes meet the standard requirements. Commonly used inspection methods include eddy current inspection, water pressure inspection, ultrasonic inspection, radiographic inspection, etc., to detect defects inside and outside the steel pipe and ensure reliable product quality.