阅读说明：本技术 一种内螺纹无缝钢管生产工艺 (Production process of internal thread seamless steel pipe ) 是由 周益鑫 于 2019-09-17 设计创作，主要内容包括：本发明公开了一种内螺纹无缝钢管生产工艺,包括以下步骤：1)管坯的长度和表面处理；2)穿孔；3)轧管；4)减径；5)测量；6)前热处理；7)冷却和表面处理；8)冷拔：9)后热处理；10)检验和矫正。本发明属于钢管生产技术领域,具体是提供了一种控制管材热轧的工艺和管材热轧后的截面形状从而降低冷拔过程中材料的形变量、降低冷拔的难度、提高冷高效率和管材强度,使用热处理消除冷拔前材料的内应力从而避免冷拔后出现斗纹缺陷,合理使用酸洗和打磨提高热轧和冷拔前材料表面光滑程度消除表面缺陷的内螺纹无缝钢管生产工艺。(The invention discloses a production process of an internal thread seamless steel pipe, which comprises the following steps: 1) the length and the surface of the tube blank are treated; 2) perforating; 3) rolling a pipe; 4) reducing the diameter; 5) measuring; 6) pre-heat treatment; 7) cooling and surface treatment; 8) cold drawing: 9) post heat treatment; 10) and (6) checking and correcting. The invention belongs to the technical field of steel pipe production, and particularly provides an internal thread seamless steel pipe production process which controls a pipe hot rolling process and a cross section shape of a pipe after hot rolling so as to reduce the deformation amount of a material in a cold drawing process, reduce the difficulty of cold drawing, improve the cold efficiency and the pipe strength, eliminate the internal stress of the material before cold drawing by using heat treatment so as to avoid the occurrence of a bucket line defect after cold drawing, and reasonably use acid washing and grinding to improve the surface smoothness of the material before hot rolling and cold drawing so as to eliminate the surface defect.)

1. The production process of the internal thread seamless steel pipe is characterized by comprising the following steps: the method comprises the following steps:

shearing and surface treatment: shearing the pipe blank to a proper length, and carrying out acid pickling and polishing on the surface of the pipe blank;

step two:

perforating: heating the tube blank to 1100-1200 ℃, and conveying the tube blank to a perforating machine for perforation;

step three:

tube rolling: after punching, the steel pipe is pulled to an automatic pipe mill by a steel pulling machine to carry out three-roller skew rolling;

step four:

reducing the diameter: carrying out hot rolling and reducing on the steel pipe by using a reducing mill, wherein the temperature of the steel pipe after the pipe is rolled is 840-900 ℃;

step five:

measurement: measuring the inner diameter and the outer diameter of the steel pipe after the reducing treatment, and entering a sixth step if the difference between the cross section shape of the steel pipe after the reducing treatment and the theoretical cross section of the finished steel pipe is within an allowable range; if the difference between the section shape of the steel pipe after the diameter reduction and the section of the finished product just managed theory exceeds the allowable range, entering the step one;

step six:

pre-heat treatment: the temperature is controlled within the range of 600-1050 ℃ and the time is 30-120 minutes, so that the stress generated in the hot rolling and reducing processes of the tube blank is eliminated;

step seven:

cooling and surface treatment: after the pipe blank is cooled, carrying out acid pickling and polishing treatment to ensure the smoothness and the smoothness of the surface of the pipe blank;

step eight:

cold drawing: and (4) carrying out cold drawing by using an inner die with a thread shape to form uniform threads on the inner surface of the pipe wall.

Step nine:

post heat treatment: the temperature is controlled within the range of 600-1050 ℃ and the time is 30-120 minutes, so that the stress generated in the process of cold drawing of the tube blank is eliminated;

step ten:

and (3) checking and correcting: and (4) carrying out precision inspection on the steel pipe after heat treatment, correcting if the steel pipe does not meet the requirement, and returning to the heat treatment process in the step nine after correction until the inspection meets the requirement.

2. The production process of the internally threaded seamless steel tube according to claim 1, characterized in that: the diameter reduction amount in the fourth step is controlled to be 20-25%.

3. The process for producing an internally threaded seamless steel tube according to claim 1, wherein the outer diameter of the tube blank measured in the fifth step is R1, the inner diameter of the tube blank is R2, the required outer diameter of the finished product is R1, the required inner diameter of the finished product is R2, and the height of the internal threads of the finished product is h, so that 1.3R 1> R1> 1.1R 1 and 1.2 (R2+0.5h) > R2> (R2+0.5h) are satisfied, and the difference between the cross-sectional shape of the steel tube after diameter reduction and the theoretical cross-sectional shape of the finished steel tube is considered to be within an allowable range.

Technical Field

The invention belongs to the technical field of steel pipe production, and particularly relates to a production process of an internal thread seamless steel pipe.

Background

The inner thread seamless steel tube is a special-shaped seamless steel tube with spiral convex ribs on the inner surface, and is generally used in a pressure boiler, because the inner wall of the inner thread seamless steel tube is provided with concave and convex inner threads, the laminar flow phenomenon generated when a medium in the steel tube flows at a low speed can be effectively overcome, the steam film effect of the inner wall of the steel tube can be inhibited, the heat transfer effect of a water cooling wall of the boiler is improved, and the temperature of the tube wall is more uniform. At present, the production process adopted by the internal thread seamless steel pipe is complex, has no unified standard, causes uneven quality of produced steel parts, has low production efficiency due to a plurality of repeated procedures, increases the labor burden of workers and simultaneously causes low market competitiveness of products.

Because the inner surface of the internal thread seamless steel pipe needs to be formed into uneven threads through cold drawing, the size of a pipe material before cold drawing has great influence on the cold drawing effect, the cold drawing efficiency can be influenced if the pipe wall is too thick, and the pipe wall strength after cold drawing is not enough if the pipe wall is too thin; in addition, the surface smoothness of the product after cold drawing is influenced by insufficient surface treatment effect of the pipe material before cold drawing, and the pipe material surface can form a slideway due to insufficient pickling or residual iron oxide scale; the hot rolled steel sheet has uneven properties after heat treatment, and thus, the surface of the steel sheet may have a streak.

Disclosure of Invention

In order to solve the existing problems, the invention provides the production process of the internal thread seamless steel tube, which reduces the deformation degree of cold drawing by controlling the hot rolling process of the tube, thereby reducing the difficulty of cold drawing, improving the strength of the finished steel tube, improving the surface smoothness and smoothness of the tube blank by the surface treatment process, avoiding the surface scratches on the surface of the finished product after cold rolling, and eliminating the internal stress of the tube before cold drawing by proper heat treatment, thereby reducing the hopper marks on the surface of the finished product after cold drawing.

The technical scheme adopted by the invention is as follows: a production process of an internal thread seamless steel pipe comprises the following steps:

the method comprises the following steps:

shearing and surface treatment: shearing the pipe blank to a proper length, and carrying out acid pickling and polishing on the surface of the pipe blank;

step two:

perforating: heating the tube blank to 1100-1200 ℃, and conveying the tube blank to a perforating machine for perforation;

step three:

tube rolling: after punching, the steel pipe is pulled to an automatic pipe mill by a steel pulling machine to carry out three-roller skew rolling;

step four:

reducing the diameter: carrying out hot rolling and reducing on the steel pipe by using a reducing mill, wherein the temperature of the steel pipe after the pipe is rolled is 840-900 ℃;

step five:

measurement: measuring the inner diameter and the outer diameter of the steel pipe after the reducing treatment, and entering a sixth step if the difference between the cross section shape of the steel pipe after the reducing treatment and the theoretical cross section of the finished steel pipe is within an allowable range; if the difference between the cross section shape of the reduced steel pipe and the theoretical cross section of the finished light pipe exceeds the allowable range, entering the step one;

step six:

pre-heat treatment: the temperature is controlled within the range of 600-1050 ℃ and the time is 30-120min, so that the stress generated in the hot rolling and reducing processes of the tube blank is eliminated;

step seven:

cooling and surface treatment: after the pipe blank is cooled, carrying out acid pickling and polishing treatment to ensure the smoothness and the smoothness of the surface of the pipe blank;

step eight:

cold drawing: cold-drawing the inner die with a thread shape to form uniform threads on the inner surface of the tube wall;

step nine:

post heat treatment: the temperature is controlled within the range of 600-1050 ℃ and the time is 30-120min, so that the stress generated in the process of cold drawing of the tube blank is eliminated; step ten:

and (3) checking and correcting: and (4) carrying out precision inspection on the steel pipe after heat treatment, correcting if the steel pipe does not meet the requirement, and returning to the heat treatment process in the step nine after correction until the inspection meets the requirement.

Further, the production process of the internal thread seamless steel pipe comprises the following specific steps:

1) the diameter reduction amount in the fourth step is controlled to be 20-25%;

2) the outer diameter of the pipe blank measured in the step five is R1, the inner diameter of the pipe blank is R2, the required outer diameter of the finished product is R1, the required inner diameter of the finished product is R2, and the height of the internal thread of the finished product is h, so that the requirements that 1.3R 1 is greater than R1, 1.1R 1 and 1.1 (R2+0.5h) > R2 (R2+0.5h) are met, and the difference between the cross section shape of the reduced steel pipe and the theoretical cross section of the finished steel pipe is considered to be within an allowable range;

compared with the prior art, the production process of the internal thread seamless steel pipe has the following beneficial effects:

1. the hot rolling treatment is carried out before the tube blank is cold drawn, the section shape of the tube blank after the hot rolling is controlled to be close to the section shape of a finished tube, the difficulty requirement of the cold drawing is reduced, the deformation quantity of the tube blank in the cold drawing process is reduced, the energy consumption and the rejection rate in the cold drawing process are reduced, the strength loss of the tube blank caused by the cold drawing is reduced, and the mechanical strength of the finished tube is improved.

2. According to the invention, the post-heat treatment process of the tube blank is added after the diameter of the tube blank is reduced, so that the internal stress generated in the hot rolling and reducing processes of the steel tube is eliminated, and the formation of surface bucket marks in the cold drawing process caused by the internal stress of the tube blank is avoided.

3. The working procedures of water washing and polishing of the workpiece are set before the working procedures of hot rolling and cold drawing, so that the surface glossiness of the finished product part caused by uneven surface or impurities of the tube blank can be avoided in the hot rolling and cold drawing processes.

Drawings

FIG. 1 is a block diagram of the overall process of an internal thread seamless steel tube production process.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

A production process of an internal thread seamless steel pipe comprises the following specific steps:

shearing the pipe blank to a proper length, carrying out acid cleaning on the surface of the pipe blank, then checking the surface defects and the smoothness degree, and polishing and repairing by using a grinding wheel; heating the tube blank to 1100-1200 ℃, and conveying the tube blank to a perforating machine for perforation; after punching, the steel pipe is pulled to an automatic pipe mill by a steel pulling machine to carry out three-roller skew rolling; hot rolling and reducing the steel pipe by using a reducing mill, wherein the reducing amount is controlled to be 20-25%; measuring the inner diameter and the outer diameter of the steel pipe after the reducing treatment, returning to the pickling step if the difference between the cross section shape of the steel pipe after the reducing treatment and the theoretical cross section of the finished product light pipe exceeds an allowable range, and performing a heat treatment step if the difference between the cross section shape of the steel pipe after the reducing treatment and the theoretical cross section of the finished product steel pipe is within the allowable range, wherein the temperature is controlled within the range of 600-1050 ℃ and the time is 30-120 min; after the tube blank is cooled, carrying out acid pickling and polishing treatment; after polishing, cold drawing by using an inner die with a thread shape; performing post heat treatment again after cold drawing, wherein the temperature is controlled within the range of 600-1050 ℃ and the time is 30-120 min; and (3) carrying out precision inspection on the steel pipe subjected to post-heat treatment, if the steel pipe does not meet the requirement, correcting, returning to the post-heat treatment process after correction until the inspection meets the requirement, carrying out manual inspection and nondestructive inspection after the precision inspection is qualified, and packaging and warehousing after the precision inspection is qualified.