Seamless Steel Pipe Production Method

(1) Automatic pipe rolling production
One of the ways to produce seamless steel pipes. The production equipment consists of punching machines, automatic pipe rolling machines, leveling machines, sizing machines and reducing machines.
(2) Continuous rolled pipe production
The production equipment consists of punching machine, continuous pipe rolling machine and tension reducing machine. The round billet is punched into a capillary tube and then inserted into a mandrel, and then rolled continuously through a two-roll mill with 7 to 9 roll axes arranged at 90° to each other. After rolling, the core-pulled rod is reheated and tension-reduced, and can be rolled into steel pipes up to 165m. The annual output of the 140mm continuous pipe rolling unit is 400,000 to 600,000 tons, which is 2 to 4 times that of the automatic pipe rolling unit. The characteristics of this kind of unit are that it is suitable for producing steel pipes with an outer diameter of less than 168mm. It requires large equipment investment, large installed capacity, a mandrel up to 30m long, and complex processing and manufacturing.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(3) Periodic rolled pipe production
Polygonal and round steel ingots or continuous casting billets are used as raw materials. After heating, they are perforated by water pressure to form cup-shaped blanks, which are then rolled into rough tubes by a two-roll cross-rolling elongation machine. Then, they are rolled on a periodic pipe rolling machine with variable diameter hole slots. The roller rotates once to roll out a section of steel pipe. The cycle pipe rolling machine is also called the Pilger pipe rolling machine. Cycle rolling pipe production uses steel ingots as raw materials and is suitable for rolling large-diameter thick-walled steel pipes and variable-section pipes.
(4)Three-roll pipe production
Mainly used to produce thick-walled tubes with high dimensional accuracy. The wall thickness accuracy of pipes produced by this method reaches ±5%, which is about twice as accurate as pipes produced by other methods. In the 1960s, due to the invention of the new three-roller cross-rolling mill (called Transval mill), this method developed rapidly. The characteristic of the new rolling mill is that when rolling to the tail, the entrance rotary frame is quickly rotated to change the rolling angle, thereby preventing the formation of a triangle at the tail, and expanding the ratio of the outer diameter to the wall thickness of the production variety from 12 to 35, which can not only produce thin-walled tubes , and also increased production capacity

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(5) Pipe jacking production
The traditional method is to extend the billet into a cup-shaped capillary tube through hydraulic perforation and cross-rolling. The long mandrel is inserted into the bottom of the capillary cup by a push rod, and then passes through a series of roller mold frames with gradually decreasing holes, and is rolled into a tube. . This production method has low equipment investment and can be used for continuous casting billets. It can produce extra large and extra thick pipes with diameters up to 1070mm and wall thicknesses up to 200mm. However, the production efficiency is low, the wall thickness is relatively thick, and the pipe length is short compared to the efficiency. After the emergence of the new process of the CPE method, the pipe blank is cross-rolled and perforated into a raw pipe, and then top-rolled and extended into a pipe after closing. This method overcomes some shortcomings of the traditional method and has become a method with better economic benefits in the production of seamless pipes.
(6) Extruded tube production
First, the peeled round billet is perforated or expanded, and then heated by induction heating or salt bath, and the inner surface is coated with lubricant and sent to the extruder. The metal is extruded into a pipe through the annular gap between the die hole and the mandrel. . It is mainly used to produce low-plasticity high-temperature alloy pipes, special-shaped pipes, composite pipes, non-ferrous metal pipes, etc. This method has a wide production range but low output. In recent years, extruded tube production has also developed due to improvements in mold materials, lubricants, extrusion speeds, etc.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(7) Guide plate rolled pipe production
Also known as Diessel method. After perforation, the capillary tube with a long mandrel is rolled into a thin-walled tube on a guide plate rolling machine. The rolling mill is similar to a two-roll cross-rolling piercing machine, except that the fixed guide plate is changed to an active guide plate. Because it is produced with a long mandrel, the inner wall of the pipe is smooth and has no scratches; however, the tool cost is high and the adjustment is complicated. It is mainly used to produce general-purpose carbon steel pipes with an outer diameter of less than 150mm. Currently it is rarely used and does not have great development prospects.
(8)Spinning tube production
The flat plate or hollow blank is processed into a thin-walled pipe by one or more spins on a spinning machine. The tubes have high precision, good mechanical properties and a wide range of sizes, but the production efficiency is low. Mainly used for the production of non-ferrous metal pipes, but increasingly also used for the production of steel pipes. In addition to being used in the production of household appliances, chemical containers and machine parts, spinning pipes are mostly used in the military industry.
(9) Cold rolled and cold drawn tube production
Used to produce small-diameter thin-walled, precision and special-shaped pipes. The production is characterized by a multi-step cycle process. Cold rolling using a periodic cold rolling pipe machine can achieve an elongation of 6 to 8. In the 1960s, it began to develop in the direction of high speed, multi-line, long stroke, and long tube blanks. In addition, small-roller cold-rolled pipe machines have also been developed. It is mainly used to produce ultra-thin precision pipes with a wall thickness less than 1mm. The cold rolling equipment is complicated, the tool processing is difficult, and the change of varieties and specifications is inflexible. A combined process of cold rolling and cold drawing is usually used, that is, the wall is reduced by cold rolling first to obtain a large deformation. , and then cold drawn to obtain a variety of specifications.