Steel pipes with equal and unequal side lengths are rolled from strip steel through technological treatment. The strip steel is unpacked, flattened, crimped, welded to form a round tube, and then rolled into a square tube from the round tube and then cut into The length required. The allowable deviation of the wall thickness of the square tube produced by the square tube manufacturer shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is not greater than 10mm, and plus or minus 8% of the wall thickness when the wall thickness is greater than 10mm. %, except for wall thickness in corners and weld areas.

During the production process, the hardness of the square rectangular tube was tested. Hardness is an index to measure the hardness and softness of metal materials. In production, the most commonly used method for measuring the hardness of rectangular tubes is the indentation hardness method. It uses a certain geometric shape of the indenter to press into the surface of the tested metal material under a certain load and tests its hardness value according to the degree of indentation. The cutting methods of square rectangular tubes mainly include:

(1) The pipe-cutting machine has the advantages of simple equipment, low investment, and a wide application range. It is mainly divided into the following five categories: (1) Pipe cutting machine. The pipe-cutting machine has the advantages of simple equipment, low investment, and a wide application range. Some also have the function of pouring tanks and automatic loading and unloading and collecting devices. The pipe cutting machine is a common equipment in the square pipe finishing production line. (2) Pipe saws can be divided into gang saws, band saws, and circular saws. The pipe saw can cut the multi-branch square rectangular pipe at one time, and the production efficiency is high, but the equipment structure is complex and the investment is high. Band saws and circular saws have low production efficiency and low investment. Circular saws are suitable for cutting rectangular tubes with smaller outer diameters, and band saws are suitable for cutting rectangular tubes with larger outer diameters. (3) The sawing machine has the characteristics of convenient incision trimming and welding during construction, but its disadvantages are that the efficiency is too low and the speed is too slow: (4) The cutting efficiency of the machine tool is low, and it is generally used for square rectangular tube sampling and sample preparation; (5) Flame cutting, flame cutting includes oxygen cutting, oxyhydrogen cutting, and plasma cutting. This cutting method is more suitable for cutting ultra-large diameter thick-walled seamless steel pipes. Plasma cutting, cutting speed is faster. Due to the high temperature of flame cutting, there is a heat-affected zone near the cut, and the surface of the end of the rectangular tube is not smooth.