High precision cold drawing pipe refers to the precision of the dimension of inner and outer diameter (tolerance range), the precision of the inner and outer surface finish, the roundness, the straight degree, the uniform wall thickness and the precision steel pipe. After a little honing, the product can be directly used as a hydraulic and pneumatic cylinder. The production process of the traditional hydraulic and pneumatic cylinder block pipe is to use the hot rolled seamless steel tube and the boring process. In the production process, a large number of metals are cut into chips and waste a lot of electric energy.

高精度冷拔管（液压缸体）与传统的切削工艺比较，具有以下特点：

The high-precision cold drawn tube (hydraulic cylinder) has the following characteristics compared with traditional cutting technology.

(1)生产效率高：用传统的方法生产一根内径420毫米，12米长的缸筒需154小时，用冷拔方法生产只需4分钟。

(1) the production efficiency is high: the production of a cylinder with an inner diameter of 420 millimeters and 12 meters long takes 154 hours by traditional way, and only 4 minutes by cold drawing.

(2)正品率高：由于镗孔的滚压头兼起导向作用，在切削过程中，毛坯管由于自重产生挠度，致使滚压头和镗刀走偏，造成废品。正品率只能达到60%左右，而用冷拔方法生产，正品率可达95%以上。

(2) high quality: due to the rolling head and guiding role of boring, in the process of cutting, the blank tube caused by self weight deflection, resulting in rolling head and boring cutter deviation, resulting in waste. The yield of genuine products can only reach about 60%, while the yield of certified products can reach more than 95%.

(3)金属利用率高：用传统的镗孔方法制造缸体，金属利用率只有50～70%。用拉拔方法生产时，金属不但不被切削成铁末，反而可以得到30%的延伸，金属利用率可达95%。

(3) the metal utilization rate is high: the traditional boring method is used to make the cylinder block, and the utilization rate of metal is only 50 to 70%. When drawing, the metal can not only be cut into iron, but can be extended by 30%, and the utilization rate of metal can reach 95%.

(4)能改善成品管金属的机械性能：用拉拔方法生产，使毛坯得到30%以上的塑性变形，由于加工硬化而使成品管金属的强度限大为提高。一般在成品管内层强度限提高达60%。高精度冷拔管是用无缝热轧钢管、直缝焊管为坯料，经过化学处理后在专用冷拔机上，通过特种变形原理设计的模具进行拉拔，生产出高精度管。其尺寸精度达H10～H8，直线度达0.35～0.5mm/m，表面粗糙度达Ra1.6～0.4。

(4) the mechanical properties of the finished tube metal can be improved: the drawing method is used to make the blank get more than 30% plastic deformation. Because of the processing hardening, the strength limit of the finished tube metal is greatly increased. In general, the inner strength limit of the finished product pipe is up to 60%. The high precision cold drawing tube is made of seamless hot rolled steel tube and straight welded pipe for blank. After chemical treatment, it is drawn on the special cold drawing machine through special deformation principle. The high precision tube is produced. The size accuracy is H10 ~ H8, the straightness is 0.35 ~ 0.5mm/m, and the surface roughness is Ra1.6 ~ 0.4.