Cold drawn pipes are very common in industry and are a widely used type of steel pipe.
Cold drawn steel pipes are made from hot-rolled pipes, and the selection of the material, specifications, and quality of hot-rolled pipes directly affects the drawing process and the quality of the finished product. When selecting materials, the following points should be noted:
(1) When selecting materials, materials with low hardness and good plasticity are generally selected while ensuring strength;
(2) The specifications of steel pipes should be selected based on the specifications of the finished product, ensuring that their elongation is between 20% and 40%; If the elongation is too small, the surface strength of the finished product cannot be guaranteed, and if it is too large, it makes it difficult to carry out the drawing process;
(3) The surface of the material should not have serious defects such as pits, cracks, cracks, folds, scars, ellipses, etc;
(4) It is recommended to select steel pipes that have been hot-rolled and placed for 0.5-2a. If the time is too short, the surface rust of the steel pipes will be shallow, and if the time is too long, the surface rust of the steel pipes will be too deep. These can lead to insufficient pre-treatment of the steel pipe surface, thereby affecting the surface quality of the finished product.
Unprocessed steel pipes cannot be drawn during cold drawing due to excessive friction coefficient between the surface of the steel pipe and the mold; Only through the pre-treatment process, can the steel pipe be rust removed first, and through phosphating, saponification, and other treatments, a dense metal soap film is formed on its inner and outer surfaces to reduce friction between the steel pipe and the mold, thus ensuring the smooth progress of drawing. At the same time, pre-treatment can also reduce the loss rate of the mold, improve the yield and work efficiency, and make the surface of the processed product smooth and uniform, with good rust prevention effect.
The following points should be noted in the pre-treatment of steel pipes:
(1) Acid cleaning and rust removal should be thorough. Once any rust that has not been removed is found, it needs to be re pickled.
(2) During production, the composition concentration of phosphating solution and saponification solution should be regularly tested to ensure the production indicators of the phosphating solution and saponification solution. If the indicators are not met, timely mixing should be carried out.
(3) Strictly control the temperature and operating time of the treatment solution.
Cold drawn pipes are made by drawing a certain shape and size mold under the action of force, and the dimensional accuracy and surface quality of the mold directly affect the dimensional accuracy and quality of the finished product.
Mold design should pay attention to the following aspects:
(1) The determination of internal and external mold sizing should consider the rebound amount of the finished product after cold drawing. Generally, materials with low hardness and small deformation have a small rebound amount, while materials with high hardness and large deformation have a large rebound amount;
(2) The surface of the mold should have a lower roughness requirement, usually one to two levels lower than the finished product;
(3) The mold material is made of high-strength and wear-resistant materials.
New Gapower metal is a professional steel pipe manufactuer, the size from OD6mm to 273mm, thickness is from 0.5mm to 35mm. The steel grade could be ST35 ST37 ST44 ST52 42CRMO4, S45C CK45 SAE4130 SAE4140 SCM440 etc. Welcome customer to inquire and visit to the factory.
Post time: Nov-07-2023