99热这里-欧亚av-色先锋av-国产草逼视频-91在线亚洲-成人性生活免费视频-午夜影院污-樱桃香蕉视频-精品久久久一区-男人天堂亚洲天堂-国产美女视频一区-欧美一级性片-av在线色-99r在线视频-一区二区的视频

 Precision seamless pipe is a type of seamless pipe, which complements ordinary seamless pipes and together play an important role in modern industry.

   1 Appearance

   I believe most people are familiar with ordinary seamless pipes, which are round in shape and covered with a layer of red rust. Ordinary seamless pipes are made of carbon steel. Over time, iron oxide will form on the surface. As shown in the picture. In fact, the surface of the seamless pipe just manufactured is not this color, but a cyan color, as shown in the picture. Precision seamless pipes have fewer uses than ordinary seamless pipes, so not everyone has seen this kind of pipe. Precision seamless pipes are usually produced using a cold rolling process. The metal becomes dense after extrusion, so the outer surface becomes very bright. Since mechanical oil is needed to cool down during the production process, there is usually a thin oil layer on the outer surface of precision seamless pipes. This oil film can play a certain role in preventing rust.

 

Precision seamless pipe: the outer surface is relatively bright.

 

Ordinary seamless pipes: Seamless pipes that have been placed for a period of time have a thin layer of rust on the outer surface.

 

Freshly produced precision steel pipe: the outer surface is cyan.

 

  2 Dimensional accuracy

You can tell the difference in dimensional accuracy between the two from their names, but this is perceptual. I can tell you the difference between the two with specific numbers. The dimensional error accuracy of precision steel pipes is measured in units of 0.01mm, while the dimensional error accuracy of ordinary seamless pipes is measured in units of 0.1mm. The two are not of the same order of magnitude. The dimensional error of ordinary seamless pipes is much larger. For example, an ordinary seamless pipe with an outer diameter of 219mm, according to the national standard GB/T8162-2008, is two percent of the outer diameter, that is, 4mm. The actual measurement is 221mm, which is in line with the standard, that is, the error is 2mm. The error of ordinary precision steel pipes is much smaller. The precision steel pipe with a specification of 80mm is 0.3mm according to the national standard GB/T3639-2008, and the actual measurement is also 79.9-80.13. The measuring tool for ordinary precision seamless pipes is a caliper, while the measuring tool for precision seamless pipes is an outer diameter micrometer.

Measuring tools for precision tubes: outer diameter micrometer

 

 

  Three  Specifications

The specifications of ordinary seamless pipes are stipulated in the national standard GB/T17395-2008. According to the national standards, steel pipe factories will produce pipes of whatever specifications. Non-standard pipes are basically unavailable. The specifications of precision seamless pipes are customized according to the needs of customers. For example, for pipes with an outer diameter of 89mm, the national standards for ordinary seamless pipes include 76, 77, and 80. You cannot buy 78 ordinary seamless pipes. However, precision seamless pipes are different. If you need 78mm, you can produce 78mm.

 

4 Mechanical properties

 

Due to different production processes, there are also differences in mechanical properties between the two. The production of ordinary seamless pipes is mainly through cold drawing and hot rolling, and the production of precision pipes is mainly through cold rolling process. The cold drawing process requires multiple anneals during the production process, and the mechanical stress of seamless pipes is small. Cold-rolled pipes are mostly formed in one step, resulting in greater mechanical stress and poor plasticity. Of course, this can also be improved by annealing.

 

Five production processes

The raw materials for trial production of precision seamless pipes and ordinary seamless pipes are round steel. The round steel is sawed and perforated to form a capillary tube. The newly produced capillary tube is passed through a hot-rolling and sizing unit to form a hot-rolled pipe. The hot-rolled tube and the capillary tube have the same or reduced diameter. After the capillary tube is cooled, it undergoes multiple passes of cold drawing and annealing to form a cold drawn tube. The outer diameter of the cold drawn tube is usually much smaller than that of the capillary tube. After the capillary tube is cooled, it is directly put into the cold rolling mill and rolled one after another to form a precision tube with the required specifications.

 

Six prices

 

Generally, hot-rolled pipes have a relatively simple production process, large output, and relatively low prices. The production process of cold drawn tubes is complex, but the output is higher, so the price is lower. The precision rolled pipe products have high dimensional accuracy and low output, so the price is higher.

High precision cold drawn tube http://m.cbtea.cn