Development of main rolling technology of seamless carbon steel pipe

- Jan 24, 2019-

Development of main rolling technology of seamless carbon steel pipe

After the periodic pipe rolling process, many kinds of pipe rolling processes have appeared in the world.There are 8 kinds of tube rolling processes, including elhard tube rolling, automatic tube rolling, diesel tube rolling, three-high tube rolling, hot extrusion tube, continuous tube rolling, cold drawing (rolling) tube, hot expanding tube and so on.Give introduction respectively now.


1.Ehrhardt rolling process

In 1891, erhard invented the water pressure punching process to produce the punch cup blank, and in 1899, he completed the process of pushing the punch blank through a series of rings with gradually reduced diameter with a mandrel to produce seamless steel tubes.Also known as pipe jacking technology.


At present, the large-size seamless steel tube is still produced by the pipe pushing method, with the maximum diameter up to 1 066mm. In the 1980s, mannesmann developed this process into CPE process, mainly producing medium and small diameter seamless steel tube.


2.Automatic tube rolling process

The first automatic tube rolling mill was put into production in the United States in 1903 after Stiefel obtained the patent of the disc punch in 1895.Automatic pipe rolling mill is also known as stiver mill.After that, the automatic pipe rolling machine once became the main unit for producing seamless steel tubes.


3.Diesel rolling process and Accu Roll rolling process

Sam Diescher first conceived of the idea of introducing a rotating guide plate into a two-high inclined mill to replace the old guide plate for extended pipe rolling. The first Diescher mill was born in 1932.Half a century later, the American company AS first introduced the conical Roll into the pipe rolling machine and obtained the patent. In 1989, the world's first Accu Roll pipe rolling machine was put into production in yantai, China.


4.Three-roll pipe rolling process

This is a three-roll bevel tube rolling process in which the capillary tube is rolled and extended between the mandrel and three rollers. The three-roll tube rolling machine is also called Assel tube rolling machine.


5.Hot extrusion tube technology

Even before the mannesmann brothers invented the miter punch, they had a patent for a process that used hot extruded aluminum to produce seamless steel tubes.However, only after the successful use of glass lubricants in the 1950s, the hot extrusion technology of steel tubes was really applied and developed rapidly.The modern hot extrusion steel tube technology is mainly used for the production of high alloy and difficult deformation tubes and special-shaped tubes.


6.Continuous tube rolling process

As early as 1891, Kellogg pipe mill in the us had obtained the patent of continuous pipe rolling mill.But for a number of technical reasons, the process never really took off.It was not until the 1950s that this process developed greatly and gradually became the leading mill for producing seamless steel tubes with its high yield, high efficiency and high quality.


Throughout the above various rolling process, they were born in different periods, through continuous improvement and development of their own characteristics, to meet the market for product specifications, varieties, quality and different batch requirements.And in different periods, have formed a variety of seamless steel pipe production mode.At present, the research and development of three-roller planetary tube rolling mill (PSW) and piercing mill tube rolling process (CPS) indicate that new tube rolling process is still being explored in the world.


7.Cold drawing (rolling) of pipe

In order to expand, supplement and improve the variety and quality of hot-rolled seamless steel pipe, the secondary processing technology of tube material -- cold drawing (rolling) and hot tube expanding technology are also developed correspondingly.


Long before the production method of hot rolled seamless steel pipe was adopted, cold drawing technology has been used for the secondary processing of welded pipes.The cold rolling process was patented by American Tabl Reduing company in 1931. It adopts the deformation process (reciprocating movement of the frame and multi-pass deformation) similar to the cycle rolling mill, so it is also called cold pilger rolling mill.


The cold drawing (rolling) method can not only produce the specification varieties and high quality products which are difficult (or uneconomic) or impossible to produce by hot rolling method, but also can replace hot rolling to produce small specification steel tubes and high quality special varieties (such as bearing tubes, stainless steel tubes, etc.).At present, China's cold-drawn (rolled) products account for about 20% of the total production of seamless steel tubes, much higher than the output of the United States, Japan, Russia and other countries.


8.Thermal expansion process

The technology of hot tube expanding is the main method to produce large diameter seamless steel pipe.The maximum diameter of roller tube is up to 1 500mm, which is suitable for large-scale production.But the push type tube expanding equipment is simple, the investment is few, the output is low, only is suitable for the small batch production.


There are 36 sets of hot rolled seamless steel tube units and many sets of cold rolled (unrolled) tube units in China.There are nine types of hot rolling tube units, including continuous rolling tube unit, automatic rolling tube unit, periodic rolling tube unit, precision rolling tube unit (Accu Roll), Diescher, three-roll rolling tube unit, tube expanding tube unit, tube pushing tube unit and extrusion tube unit.Industrial test of three - roll planetary mill has also been carried out.There are also more than 100 sets (sets) of equipment to produce seamless capillaries (mainly punch machines), more than any other country in the world production unit, it can be said that the world's seamless steel tube production unit museum.


At present, the basic production process of hot rolled seamless steel tube is: blank preparation heating piercing (punching) hole adding hot rolled tube sizing finishing, inspection, testing (cooling, correction, cutting (saw) head, sampling, flaw detection, water pressure, weighing, corrosion, etc.) packaging and warehousing.


Among them, the main thermal deformation processes are piercing (punching), rolling and sizing (reducing) diameter.Piercing (punching) hole is mainly to change the solid tube blank into a hollow waste tube;Tube rolling is mainly used to reduce the wall thickness and control the wall thickness.The main purpose of reducing diameter is to reduce and control the outside diameter, and also to adjust the wall thickness (tension reducing).


Because the tube rolling process is not only the main process of tube rolling longitudinal deformation, but also plays a vital role in the control of wall thickness, surface quality and even the production efficiency of the whole unit.Therefore, people have been used to the name of the tube rolling process as the type of the unit, such as continuous tube rolling unit, automatic tube rolling unit, precision tube rolling unit and so on.


Due to the high demand for seamless steel tube quality and the efficient and rapid development of hot-rolled steel tube unit, the steel tube finishing process and equipment have been further developed and modernized.Stepping cold bed, multi-roll pipe straightening machine, efficient pipe cutting machine and pipe row saw, rapid milling head chamfering machine, automatic length measurement, weighing, printing and mechanical binding device have appeared and been widely used.The development of related technology, especially the technology of continuous casting round billet is becoming more mature and the application of on-line detection and automatic control technology promotes the development of seamless steel tube production technology.The higher quality requirements for the products and special pipes also need further heat treatment (normalizing, annealing, tempering and tempering, etc.) and machining (thread fastening, peeling, polishing, end thickening, etc.).