Empty bending empty bending is the bending moment formed in one direction between the outer roll and the outer wall of the tube blank to bend the strip. Empty bending will compress the bending line, the compression effect will lengthen the bending line longitudinally, and the metal at the bending will accumulate and thicken, which is the compression thickening effect of empty bending.According to metallographic classification, the annealed state of square tube: A. hypoeutectoid steel (ferrite + pearlite); b. Eutectoid steel (pearlite); c. Steel precipitation through a common square tube (pearlite + cementite); d. Ledeburite steel (pearlite + cementite).North Vancouver,In the case of dynamic load, plastic design usually calculates the allowable stress according to the safety factor that the allowable stress is not less than the dynamic load and multiplied by the allowable stress. In the case of bending of an axis,North VancouverManufacturing method of galvanized square pipe, it can be calculated by the formula a = W. replacing the calculated strength with plasticity can improve the bearing capacity of the member by %.Because the green billet can be pressed into any shape, it is easy to weld the square tube into difficult products.Bwizibwera,Large diameter qb square tube production standard classification square tube is divided according to production standard: national standard square tube, Japanese standard square tube, British standard square tube, American standard square tube, European standard square tube and non-standard square tube.The difference between hot-dip galvanized square pipe and cold-dip galvanized square pipe is mainly from the following aspects: the appearance of hot-dip galvanized square pipe is slightly rough compared with cold-dip galvanized square pipe; The appearance of cold galvanized square pipe is smooth and bright.The surface of fake and inferior square tubes is easy to produce scabs. There are two reasons: the material of fake and inferior square tubes is uneven and there are many impurities. The guide equipment of fake and shoddy material manufacturers is simple and easy to stick to steel. These impurities are easy to scar after biting the roll.

At this time, if the welding wire of the same material is used for spot welding where the thickness is insufficient, it shall be welded to the fixed thickness, ground and sandblasted, and repair welding shall be adopted where there are cracks, even if the steel pipe with another large opening can be made up at one time.In the standard of qb square tube, most of them specify tensile test and hardness test at the same time. For those materials that are not convenient for hardness test, such as qb square tube, only tensile test is specified. In particular, the new portable surface Rockwell hardness tester and pipe Rockwell hardness tester can quickly and accurately test the hardness of stainless steel plate, stainless steel strip and qb square tube as thin as .mm which makes it easy to solve the problems that were difficult to solve in China in the past.The difference between hot-dip galvanized square pipe and cold-dip galvanized square pipe is mainly from the following aspects: the appearance of hot-dip galvanized square pipe is slightly rough compared with cold-dip galvanized square pipe; The appearance of cold galvanized square pipe is smooth and bright.offer,Square tube is made of different materials. It needs qualified inspection by relevant staff before leaving the factory. Square tube has a wide range of uses. Its main field is not only the construction industry, and its characteristics are also different. Square tube has strict standards. There are many welding processes and advantages of square tube. Let me show you the welding process and advantages of lower tube.

For oil, the oil brush work shall be carried out in accordance with the requirements of the rule system, so as to ensure the oil brush and the oil in the correct position of the brush and avoid wrinkles.Inspection standard, square tube is generally divided into sections, plates, pipes and metal products. In order to facilitate the production, ordering and supply of square tube and do a good job in operation and management, it is also divided into heavy rail, light rail, large section steel, medium section steel, small section steel and square tube cold bending Section steel high-quality section steel, wire rod, medium and thick steel plate, sheet steel, electrical silicon steel sheet, square pipe seamless steel pipe,North VancouverDN25 galvanized welded pipe, welded steel pipe, metal products, etc.In the case of dynamic load, plastic design usually calculates the allowable stress according to the safety factor that the allowable stress is not less than the dynamic load and multiplied by the allowable stress. In the case of bending of an axis,North Vancouver80m3 galvanized square pipe, it can be calculated by the formula a = W. replacing the calculated strength with plasticity can improve the bearing capacity of the member by %.The advantage of empty bending is that it can bend the side length when the real bending cannot be carried out, such as synchronous bending and finishing of the upper side and side of qb square tube. Empty bending can also bend the inner corner of r.t without breaking the tube wall.North Vancouver,If the test results of square tubes fail to meet the provisions of product standards, the unqualified ones shall be selected, and double the number of samples shall be taken from the same batch of square tubes for re inspection of unqualified items. If the re inspection results (including any index required by the test of the project) are unqualified, re inspection is not allowed: A. There are white spots in the low magnification; b. Microscopic.The reason why it is divided into two types is that chemical cleaning can only clean the surface very thoroughly, and it is difficult to achieve the desired results in some fine cracks.Zinc layer thickness: there is a great difference between cold galvanized square pipe and hot galvanized square pipe in galvanizing process; Cold galvanized square pipes are prone to & ldquo; Electric burning & rdquo; The color of this part is gray and the zinc layer is thick. It is easy to form a current dead angle at the corner, resulting in an under current area. The zinc layer at this part is thin, and there is no zinc layer attached to the cold galvanized square pipe. The cold galvanized square pipe has no zinc lump and caking as a whole, but the overall zinc layer is thin, and the thickness of the outer wall zinc layer is μ m-μ m. The and outer walls of the hot-dip galvanized square tube are attached with zinc layer and there will be water marks and a few zinc tumors, but the overall zinc layer is thick, and the thickness of the zinc layer on the inner and outer walls of the square tube is -mu; M above. The nature of QB square tube!