Manufacturing method for cold drawn welded pipe used for hydraulic oil cylinders

Abstract

The invention relates to a manufacturing method for a cold drawn welded pipe used for hydraulic oil cylinders. The manufacturing method includes the steps of: longitudinal shearing, roll bending formation, high-frequency welding, weld joint treatment, sizing, online eddy current flow detection, stress relief annealing, pre-straightening treatment, pipe cutting, normalizing air cooling treatment, pinching, pickling treatment, phosphating treatment, saponification treatment, cold-drawing, induction furnace quenching treatment, box type furnace tempering treatment, straightening treatment, fine boring rolling, magnetic leakage flaw detection, and pipe cutting measurement. The product obtained by the method provided by the invention has the advantages of high yield strength, high tensile strength, precise size, smooth surface, fast machine shaping speed, high yield, and remarkably improved manufacturing precision. The cold drawn welded pipe has good surface smoothness and low roughness, the follow-up gold processing amount is reduced, the steel utilization is improved, the manufacturing cost is lowered, and energy saving and environmental protection are promoted.

Description

technical field [0001] The invention belongs to the technical field of steel pipe preparation, and in particular relates to a method for manufacturing cold-drawn welded pipes for hydraulic oil cylinders. Background technique [0002] In the prior art, the production process of the cylinder body of the hydraulic oil cylinder is generally made of hot-rolled seamless steel pipe, which is produced by a combined cutting process of boring and rolling. Since one of the biggest defects of the seamless steel pipe is uneven wall thickness, The main reasons are uneven heating of the tube billet, instability of the centering roll caused by the uncorrected rolling line of the piercer, wear of the plug, eccentricity of the rear hole of the plug, incorrect centering hole of the tube billet, excessive curvature of the tube billet, etc. The reason is that it is technically difficult to remove all the above reasons one by one. Therefore, the yield of seamless steel pipes is relatively low; C...

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Problems solved by technology

Using this method to manufacture the cylinder body of the hydraulic cylinder, the production speed is slow, the energy waste is large, the metal utilization rate is low, and the yield is also low.

[0003] In the prior art, the welded pipe production process is a relatively mature production technology. However, welded pipes generally cannot be used as cylinder blocks for hydraulic cylinders. The following problems limit their application in the manufacture of hydraulic cylinders: 1), welded pipes The accuracy of the pipe itself is relatively low, and its roundness is difficult to be reliably guaranteed; 2) When the welded pipe is welded, the surface weld is easy to handle, but the weld on the inner wall is difficult to handle, especially in an uninterrupted continuous production line, such as When the weld seam on the inner wall is not processed, but directly used for the processing of the oil cylinder, there is also the problem of large cutting volume; 3), the weld seam has not been heat-treated, resulting in large internal stress, and cracking is prone to occur during use; 4), Even if the weld has been heat-treated, since the welded pipe has not been drawn, its bearing capacity in the axial direction is relatively low. In order to improve its bearing capacity, it is necessary to increase the size, resulting in waste of metal materials

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