production process and mill roll selection of seamless steel pipe

by:ChangZeng     2020-07-07
The production process of seamless steel pipe and several main roller tool materials are introduced as follows: 1.
Seamless steel pipe production process seamless steel pipe production is mainly carried out through the following processes; tube -cutting -heating -perforation -rolling pipe -set (minus)diameter -straightening -
Cut the first tail. testing -packaging -storage.
According to the different Rolling methods, the seamless steel pipe mill can be divided into automatic pipe mill Group and continuous pipe mill group (MPM two-
PQF three-roller Pipe Rolling Machine Group-
Roller Pipe Rolling Machine Group)
The Assel Rolling Mill Group, periodic Tube Rolling Mill Group and new rolling mill group are mostly MPM Tube Rolling Mill Group and PQF three-roller Pipe Rolling Mill Group.
Punching punch is the most important deformation process in the production of seamless hot rolled steel pipe.
Its task is to insert the solid tube into the hollow capillary tube.
According to the structure of the hole piercing device and the deformation characteristic of the perforation process, the perforation is the most widely used.
The shape of the hole piercing roller, bacteria (cone)
There are also tray three, roller punching rollers for small grinding, and large unit punching machines with bacteria rollers.
Less disk punch applications.
Regardless of the roller type, in order to ensure that the billet and the punching process reach the perforated cone (
Involved in the mouth cone), mill cone (roll exit cone)
And rolling belt (
The entrance cone and the exit cone between the majority)composition.
The punching roller adopts the combination structure of the rolling roller, and the two adopt the direct interference combination or the key interference combination.
In this way, when the roller is scrapped, the roller axle can continue to be reused to reduce the cost of the tool.
The roller material of the small piercing machine is 45 or 40Cr, which is treated by temperature adjustment.
The roll of the large piercing machine is 42 Mbps steel, quenching and tempering.
At present, the roller materials selected by the manufacturer are more miscellaneous, and some manufacturers choose 45, 55 high-quality carbon steel forged.
Some manufacturers choose 50Mn, 65Mn, 70Mn, 70Mn2Mo, 60mnmo and other alloys or forged steel;
The hardness range requirements are inconsistent, and some requirements are HB180-
220, some need HB220-260.
In order to increase the bite, the large perforated roller is generally processed in the case of the inlet cone depth of 0. 8 ~ 1.
2mm mesh pattern.
Based on the material selection and use of domestic and foreign manufacturers, the author believes that it is more appropriate to select the punching machine roller to cast 50Mn and 60mnmo medium carbon steel. First, it has good strength and wear resistance, the second is suitable for steel pipes with rolled materials.
Hardness control in HB200-
240 is more reasonable. 3.
Tube mill capillary rolling is the main deformation process of hot rolled seamless steel pipe production, the function is to make the capillary wall thickness close to or reach the finished pipe wall thickness, in order to eliminate the capillary longitudinal wall thickness in the process of perforation, in addition to improving the surface quality inside and outside the waste material, the diameter and circular degree of the waste material are controlled.
In the case of a shortage of waste management, hollow capillary tubes enter the finished product.
A. Automatic pipe rolling machine: the automatic pipe rolling machine is two-
Vertical rolling mill with irreversible roll, which is characterized by a pair of high
Provide speed reverse Mill return roll behind work roll to send once-
The second rolling, production efficiency is low, most of the domestic units have been transformed or eliminated.
Most of the materials of roller cold hard cast iron, cast iron or cold hard cast iron, the hardness is above hsd50. b,Two-
Rolling Mill: the continuous rolling mill is a more advanced steel pipe mill, which is a capillary hole punched on the long core shaft, after the multiple racks of the continuous tube mill are arranged in sequence, the adjacent rack roller seam is 90 °.
Even the material of the roller is mostly Chrome.
Molybdenum infinite cold hard cast iron (
Also called Pearl Rock iron), nickel-
Molybdenum infinite cold hard cast iron (
Also known as needle-shaped ductile iron)
Hardness of the hole HSD50-65.
Some of the first foreigners
To further improve the strength of the rollers, the designed continuous rollers are made of forged steel or graphite. c,Three-
Rolling Mill: Three-
Rolling Mill with roller adjustable finite core rod (PQF)
INNSE Italian company overcome the inherent limitations of the two-
The development and development of the rolling mill, because it divides the 360 ° pass into three parts, reducing the speed difference between the bottom of each roller and the edge of the line, so the precision of rolling steel pipes is said.
The small PQF Mill roller is-
Workpiece using nickel
Hardness control chromium 55-chromium molybdenum infinite cooling cast iron
65 more appropriate; Large-
The scale of the PQF Rolling Mill roller is made into a combination type, which has better wear resistance of nickel chromium molybdenum infinite cold hard cast iron with high shaft
Strength Forged Steel, after quenching and tempering, can be reused, significantly saving costs, this structure has been successfully applied in Tianjin Pipe Company.
D. Assell Pipe Rolling Mill Group: Assell pipe rolling is three-
A roll formed by three active rollers and a core rod is rolled diagonally to form a circular closed channel.
The inlet cone, roller shoulder, flat area and outlet cone of the roller body are four sections. The material is made of 4Cr5MoSiV1 forged steel and cast half
Steel or alloy cast iron, heat treatment hardness: Forged steel roller control HSD65-75, semi-
Roll 50-coil control
60, alloy ball iron roller control in HSD55-65 (
Material rollers for the design of imported units, examples of less successful in China). 4.
Hot rolled seamless steel pipe production is the last link of the deformation process of the waste heat pipeline, its main role is to eliminate the previous rolling process caused by different outer diameter, in order to improve the heat-
OD precision and circular degree of rolled finished pipe.
In the absence of the core rod rolling process, the size adjustment, diameter reduction and hollow body diameter reduction of the steel.
Advanced at present (minus)
The diameter machine adopts three-
The roller is 120 ° split roller, and the surface quality of the pipe is good after setting (reducing)
With this type of machine, there are many specifications for finished pipe. Set (minus)
The diameter machine roller is connected with the shaft with interference or buttons, and the interference fit is currently used. Nickel-chromium-
Molybdenum infinite cold hard ball cast iron for rollers.
Production of blanks by centrifugal casting to ensure a dense outer layer with hardness of HSD55-68.
Steel pipes of the following specifications, the hardness of the rollers can be selected at HSD60-
68. Ensure the hardness of the hole --
Type, better wear resistance;
There are many pipe specifications for rolling φ 219, the size of the hole is large, and the gap is large. In order to ensure that the wear of the bottom and edge of the hole is not too different, the hardness of the coil can be HSD55-61.
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