Channel steel beam is a long strip of steel with a groove-shaped cross-section. It is a carbon structural steel for construction and machinery. It is a section steel with a complex cross-section. Channel steel is mainly used in building structure, curtain wall engineering, mechanical equipment and vehicle manufacturing.

China's channel steel imports are greater than its exports. The main origins are several steel mills such as Tangshan Iron and Steel, Baotou Iron and Steel, Shanshan Iron and Steel, Huangte, Maanshan Iron and Steel, Xuanyuan Iron and Steel, and Japan Iron and Steel.

In use, it is required to have good welding, riveting performance and comprehensive mechanical properties. The raw material billets for producing channel steel are carbon-structured steel or low-alloy steel billets with a carbon content not exceeding 0.25%. The finished channel steel is delivered in hot-formed, normalized or hot-rolled state. Its specifications are expressed in millimeters of waist height (h) * leg width (b) * waist thickness (d), such as 100*48*5.3, which means that the waist height is 100 mm, the leg width is 48 mm, and the waist thickness is 5.3 mm. Steel, or 10# channel steel. For channels with the same waist height, if there are several different leg widths and waist thicknesses, a b c should be added to the right side of the model to distinguish them, such as 25#a 25#b 25#c, etc.

Channel steel is divided into ordinary channel steel and light channel steel. The specification of hot-rolled ordinary channel steel is 5-40#. The specification of hot-rolled flexible channel steel supplied by agreement between the supplier and the buyer is 6.5-30#. Channel steel is mainly used in building structures, vehicle manufacturing, other industrial structures and fixed cabinets, etc. Channel steel is often used in conjunction with I-beam steel.

Channel steel can be divided into 4 types according to shape: cold-formed equilateral channel steel, cold-formed unequal-sided channel steel, cold-formed inner-curled channel steel, and cold-formed outer-curved channel steel.

According to the theory of steel structure, the channel steel wing plate should be stressed, that is to say, the channel steel should be standing, not lying down.

The specifications of channel steel are mainly expressed by dimensions such as height (h), leg width (b), waist thickness (d), etc. The specifications of domestic channel steel are from 5-40, that is, the corresponding height is 5-40cm.

At the same height, light channel steel has narrower legs, thinner waist and lighter weight than ordinary channel steel. No. 18-40 is a large channel, and No. 5-16 is a medium channel. Imported channel steel indicates the actual size and relevant standards. The import and export order of channel steel is generally based on the specifications required in use after determining the corresponding carbon steel (or low alloy steel) steel grade. Apart from the specification number, there is no specific composition and performance series for channel steel.

The delivery length of channel steel is divided into fixed length and double length, and the tolerance value is specified in the corresponding standard. The length selection range of domestic channel steel is divided into three types: 5-12m, 5-19m and 6-19m according to different specifications. The length selection range of imported channel steel is generally 6-15m.

The 400mm unit in a steel plant is a profile unit mainly producing medium angle steel and channel steel, with an annual output of 650,000 tons, of which the channel steel product specifications are 638-1208, and the output accounts for about 25% of the total output. The sectional operation of the finished channel steel is carried out by a 400t cold shearing machine. The shear quality of the channel steel has a great influence on the subsequent process, especially the welding quality. If there are defects such as collapsed shoulder, burr, tearing, and oblique cutting at the shear fracture, there will be a large gap when the channel steel is butted, which will affect the welding. quality, especially the strength index, thus causing a greater safety hazard.

With the increase of production rhythm and output, the above-mentioned shear defects are more and more prominent, and the internal control rate of shear quality is only 94.2%. Moreover, the service life of the cutting blade is getting shorter and shorter, and it is replaced once per shift on average, resulting in an increase in production costs and labor intensity of employees. Aiming at these problems, careful analysis was carried out in terms of process, technology and operation, and corresponding improvement measures were put forward, which achieved good results.

The design capacity of the unit is 200,000 t/a, but the output has reached 600,000 t/a. The problem of insufficient production capacity in the cooling bed area is very prominent. Compared with the production of angle steel, the cooling speed of channel steel is slower, resulting in shear The temperature of the channel steel during cutting is high, and defects such as shoulder collapse, burr, and tearing are prone to occur, and the life of the shearing edge is greatly affected.

The basic basis for the design of channel steel shearing edge is the shape of the finished channel steel pass, as shown in Figure 1 (take 100# channel steel as an example). This design is prone to the following problems during the shearing process: First, the two shoulders of the channel steel are relatively thicker than other parts, and the required shearing force is also larger, and the cutting edge wears quickly. . This part has a relatively large amount of wear, resulting in a large shoulder gap and prone to shoulder collapse; second, compared with the waist of the channel steel legs, due to the influence of the shearing angle, when the shearing edge is worn, the legs are cut after cutting. When the shearing amount becomes smaller, the leg shearing changes from the usual shearing to tearing, and the end face of the channel steel leg is prone to burrs. In this way, the legs are basically stressed at the same time during shearing, the shearing force is large, and the shearing edge wears quickly. Tear, burr more phenomenon. The last two points are the main reasons that affect the shear quality of channel steel.

The amount of shear overlap improves the shear quality of the channel steel shoulder; the upper width of the lower shearing edge is changed from 79mm to 80mm, and the lower width is changed from 97mm to 94mm, so that the leg end slope of the lower shearing edge is smaller than the channel slope of the finished channel steel. , so that when the leg is sheared, the upper and lower directions of the leg will not be stressed at the same time, thereby reducing the shearing force and improving the shearing quality.

There are two channels: simple import and import with complete set of projects. In recent years, several major coastal ports in my country (Dalian, Tianjin, Qinhuangdao, Lianyungang, etc.) are building or expanding the automatic loading and unloading projects of oil, coal, grain and other bulk import and export commodities. With the introduction of main equipment, the import volume of large channel steel has also increased. increasing. The main producing countries and regions are Japan, Russia and Western Europe.

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