The cold-drawn cylinder is made of hot-rolled pipe. The selection of the material, specification and quality of the hot-rolled pipe directly affects the drawing and the quality of the finished product. Pay attention to the following points when selecting materials:
(1) In the case of material selection, materials with low hardness and good plasticity are generally selected under the condition of strength guarantee;
(2) The specification of the steel pipe should be selected according to the specifications of the finished product to ensure that the elongation rate is 20% to 40%; the elongation is too small, the strength of the finished surface cannot be guaranteed, and the drawing is difficult to carry out. ;
(3) The surface of the material shall not have serious defects such as pits, cracks, cracks, folds, crusting or ellipse;
(4) It is best to choose a steel pipe with 0.5~2a after hot rolling. The time is too short, the surface of the steel pipe is rusted, the time is too long, and the surface of the steel pipe is too rusted. These will lead to insufficient pretreatment of the steel pipe surface, thus affecting the surface quality of the finished product.