A method for manufacturing thin-walled high-pressure resistant seamless steel pipe

Abstract

The present invention relates to the technical field of steel pipe preparation, and discloses a method for manufacturing a thin-walled high-pressure resistant seamless steel pipe; the method for manufacturing the thin-walled high-pressure resistant seamless steel pipe comprises the following steps: S1: confirming the components; S2: manufacturing the blank; S3: centering processing; S4: perforation preparation; S5: hole expansion and drawing; S6: tempering treatment. When manufacturing the thin-walled high-pressure resistant seamless steel pipe, the present invention adopts a blank centering perforation and performs multiple drawing and forming methods. Compared with the existing method of first making a steel plate and then cold rolling forming, the method can effectively avoid the generation of interface gaps in cold rolling forming, so that the steel pipe has no joints. In actual use, the method has higher tightness and is suitable for various occasions. Through multiple drawing and subsequent tempering treatment, the steel pipe has good service strength, tensile strength and compressive strength while ensuring thinness, thereby increasing the service life of the steel pipe by 1‑3 times.

Description

Technical Field

[0001] The invention belongs to the technical field of steel pipe preparation, and in particular relates to a method for manufacturing a thin-walled high-pressure resistant seamless steel pipe. Background Art

[0002] Steel pipes are used to transport fluids and powdered solids, exchange heat, and manufacture mechanical parts and containers. They are also an economical steel material. Seamless steel pipes refer to steel pipes made of a whole piece of metal with no seams on the surface.

[0003] In practical applications, seamless steel pipes are needed for butt jointing in many situations to ensure tightness. The existing seamless steel pipe preparation process generally involves pressing the blank into a rectangular cast sheet, bending the cast sheet into a steel pipe shape by cold rolling or hot rolling, and then heating the steel pipe. This method is difficult to ensure the tightness of the connection and may have gaps. Secondly, the production steps are relatively cumbersome and the production efficiency is low. Therefore, in view of the current situation, it is now necessary to improve it. Summary of the Invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a method for manufacturing thin-walled high-pressure resistant seamless steel pipes, which effectively solves the problem that the existing seamless steel pipe preparation process is generally to press the blank into a rectangular cast sheet, and then use cold rolling or hot rolling to bend the cast sheet into a steel pipe shape, and then heat the steel pipe. This method is difficult to ensure the tightness of the connection and there may be gaps. Secondly, the production steps are relatively cumbersome and the production efficiency is low.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for manufacturing a thin-walled high-pressure resistant seamless steel pipe, comprising the following steps:

[0006] S1: Confirm the composition: When manufacturing thin-walled high-pressure resistant seamless steel pipes, first confirm the manufacturing composition, that is, mix C, Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W as the main components in an appropriate proportion to manufacture thin-walled high-pressure resistant seamless steel pipes;

[0007] S2: Billet manufacturing: Based on the above step S1, after confirming the composition of the thin-walled high-pressure resistant seamless steel pipe, the prepared C, Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W components are placed in a casting furnace for billet manufacturing. When manufacturing the billet, the casting furnace is first heated to 1000-1500°C to melt the components, and the melting time is controlled to 1-2 hours. After the melting is completed, the casting furnace is first cooled to 600-700°C, and the cooled molten material is placed in a billet manufacturing mold. After cooling for 2-3 hours until the temperature reaches 300-400°C, the billet manufacturing is completed and it is transferred to the next step of manufacturing:

[0008] S3: Centering processing: Based on the above step S2, the blank is transferred to the centering machine, and the blank is centered by the centering machine. During the centering process, the centering depth is controlled to be 1 / 4-1 / 3 of the blank length;

[0009] S4: Perforation preparation: Based on the above step S3, the billet that has been centered is transferred to a roller cross-rolling piercing machine, and the billet is perforated by the roller cross-rolling piercing machine. During the perforation process, the billet is processed to 600-700°C, and the thickness of the steel pipe is controlled to 1 / 4-1 / 3 of the billet diameter. The billet is processed again to 800-900°C, and the thickness of the steel pipe is controlled to 1 / 6-1 / 5 of the billet diameter by the roller cross-rolling piercing machine. Finally, the billet is processed to 900-1000°C, and the thickness of the steel pipe is controlled to 1 / 8-1 / 7 of the billet diameter by the roller cross-rolling piercing machine;

[0010] S5: Hole expansion and drawing: Based on the above step S4, the perforated steel pipe is transferred to the drawing pipe expansion unit, and the steel pipe is expanded and drawn again using a small variable multiple expansion and drawing method. The amount of each expansion and drawing is controlled to 1 / 10-1 / 12 of the thickness of the steel pipe. During this process, the temperature environment is 600-650℃.

[0011] S6: Tempering treatment: Based on the above step S5, the steel pipe after hole expansion and drawing is tempered again, that is, the steel pipe is placed at a normalizing temperature of 600-900℃ for normalizing heat treatment, and then accelerated cooling is performed at an average cooling rate of 20-80℃ / s until the cooling stop temperature reaches below 350℃, thereby completing the manufacture of thin-walled high-pressure resistant seamless steel pipe.

[0012] Preferably, in step S1, the main components are C 25-30%, Si 5-10%, Mn 10-12%, P 5-8%, S 5-10%, Al 10-15%, Cu 5-7%, Ni 5-10%, Mo 10-20%, C 5-10% and W 5-10%.

[0013] Preferably, in step S2, when manufacturing the blank, C is first placed in a casting furnace and heated to 1000-1200°C. After casting for 30-50 minutes, a mixture of Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W is added to the casting furnace and heated to 1200-1500°C.

[0014] Preferably, the mixture of Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W is mixed by a mixer, specifically a JDC350 automatic mixer, and during mixing and stirring, the speed is controlled at 800-1000 r / min, and the mixing and stirring time is controlled at 10-15 min.

[0015] Preferably, in step S3, the centering machine is specifically a 600SBRZ crankshaft centering machine, and when performing the centering process, the blank surface is centered using an optical centering method.

[0016] Preferably, in step S4, the roller cross-rolling piercing machine is specifically a JB / T13124-2017 two-roller cross-rolling piercing machine. Before hole preparation, the blank needs to be tempered once, and during tempering, the tempering temperature is controlled at 400-500°C.

[0017] Preferably, in step S5, the pulling-type pipe expanding machine unit is a 100-ton pulling-type pipe expanding machine unit, and the specific model is LLJZ-4-1 continuous pulling-type pipe expanding machine unit.

[0018] Preferably, in step S6, after the tempering treatment, the steel pipe needs to be subjected to general inspection, namely, appearance inspection, crack inspection, strength inspection, stress inspection and tension inspection.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. When manufacturing thin-walled high-pressure resistant seamless steel pipes, the blank is pierced centrally and drawn multiple times. Compared with the prior art method of first making steel plates and then cold-rolling, the present invention can effectively avoid the generation of interface gaps during cold-rolling, making the steel pipe seamless. In actual use, the steel pipe has higher tightness and is suitable for a variety of occasions.

[0020] 2. Through multiple drawing and subsequent tempering treatment, the steel pipe has good strength, tensile strength and compressive strength while ensuring thinness, thereby increasing the service life of the steel pipe by 1-3 times;

[0021] 3. The entire preparation process is more concise, suitable for mass production, and can ensure production efficiency and quality. It has the characteristics of high yield rate and is suitable for large-scale industrial batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0023] In the attached figure:

[0024] Figure 1The present invention is a flow chart of a method for manufacturing a thin-walled, high-pressure resistant seamless steel pipe. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, the present invention provides a technical solution: a method for manufacturing a thin-walled high-pressure resistant seamless steel pipe, comprising the following steps:

[0027] S1: Confirm the composition: When manufacturing thin-walled high-pressure resistant seamless steel pipes, first confirm the manufacturing composition, that is, mix C, Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W as the main components in an appropriate proportion to manufacture thin-walled high-pressure resistant seamless steel pipes;

[0028] S2: Billet manufacturing: Based on the above step S1, after confirming the composition of the thin-walled high-pressure resistant seamless steel pipe, the prepared C, Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W components are placed in a casting furnace for billet manufacturing. When manufacturing the billet, the casting furnace is first heated to 1000-1500°C to melt the components, and the melting time is controlled to 1-2 hours. After the melting is completed, the casting furnace is first cooled to 600-700°C, and the cooled molten material is placed in a billet manufacturing mold. After cooling for 2-3 hours until the temperature reaches 300-400°C, the billet manufacturing is completed and it is transferred to the next step of manufacturing:

[0029] S3: Centering processing: Based on the above step S2, the blank is transferred to the centering machine, and the blank is centered by the centering machine. During the centering process, the centering depth is controlled to be 1 / 4-1 / 3 of the blank length;

[0030] S4: Perforation preparation: Based on the above step S3, the billet that has been centered is transferred to a roller cross-rolling piercing machine, and the billet is perforated by the roller cross-rolling piercing machine. During the perforation process, the billet is processed to 600-700°C, and the thickness of the steel pipe is controlled to 1 / 4-1 / 3 of the billet diameter. The billet is processed again to 800-900°C, and the thickness of the steel pipe is controlled to 1 / 6-1 / 5 of the billet diameter by the roller cross-rolling piercing machine. Finally, the billet is processed to 900-1000°C, and the thickness of the steel pipe is controlled to 1 / 8-1 / 7 of the billet diameter by the roller cross-rolling piercing machine;

[0031] S5: Hole expansion and drawing: Based on the above step S4, the perforated steel pipe is transferred to the drawing pipe expansion unit, and the steel pipe is expanded and drawn again using a small variable multiple expansion and drawing method. The amount of each expansion and drawing is controlled to 1 / 10-1 / 12 of the thickness of the steel pipe. During this process, the temperature environment is 600-650℃.

[0032] S6: Tempering treatment: Based on the above step S5, the steel pipe after hole expansion and drawing is tempered again, that is, the steel pipe is placed at a normalizing temperature of 600-900℃ for normalizing heat treatment, and then accelerated cooling is performed at an average cooling rate of 20-80℃ / s until the cooling stop temperature reaches below 350℃, thereby completing the manufacture of thin-walled high-pressure resistant seamless steel pipe.

[0033] Wherein, in step S1, the main components are specifically C25-30%, Si5-10%, Mn10-12%, P5-8%, S5-10%, Al10-15%, Cu5-7%, Ni5-10%, Mo10-20%, C5-10% and W5-10%; in step S2, when manufacturing the billet, first put C into the casting furnace and heat it to 1000-1200℃. After casting for 30-50min, add Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W mixture into the casting furnace and heat it to 1200-1500℃; Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W mixture are mixed by a mixer, which is specifically a JDC350 automatic mixer, and when mixing and stirring, The speed is controlled at 800-1000r / min, and the mixing time is controlled at 10-15min; in step S3, the centering machine is specifically a 600SBRZ crankshaft centering machine, and during the centering process, the blank surface is centered by an optical centering method; in step S4, the roller oblique rolling and piercing machine is specifically a JB / T13124-2017 two-roller oblique rolling and piercing machine, and before hole preparation, the blank needs to be tempered once, and during tempering, the tempering temperature is controlled at 400-500℃; in step S5, the drawing-type pipe expanding unit is a 100-ton drawing-type pipe expanding unit, and the specific model is LLJZ-4-1 continuous drawing-type pipe expanding unit; in step S6, after the tempering treatment, the steel pipe needs to be subjected to general inspection, namely appearance inspection, gap inspection, strength inspection, stress inspection and tension inspection.

[0034] Through the above steps, when manufacturing thin-walled high-pressure resistant seamless steel pipes, the blank is centered and pierced, and multiple drawing and forming methods are adopted. Compared with the existing method of first making a steel plate and then cold rolling, the generation of interface gaps in cold rolling can be effectively avoided, so that the steel pipe is seamless. In actual use, the tightness is higher and it is suitable for various occasions. Through multiple drawing and subsequent tempering treatment, the steel pipe has good service strength, tensile strength and compressive strength while ensuring thinness, thereby increasing the service life of the steel pipe by 1-3 times. The entire preparation process is more concise, suitable for mass production, and can ensure production efficiency and production quality. It has the characteristics of high yield rate and suitability for large-scale industrial mass production.

[0035] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0036] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a thin-walled, high-pressure resistant seamless steel pipe, characterized in that: The following steps are involved: S1: Confirm the composition: When manufacturing thin-walled high-pressure resistant seamless steel pipes, first confirm the manufacturing composition, that is, mix C, Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W as the main components in an appropriate proportion to manufacture thin-walled high-pressure resistant seamless steel pipes; S2: Billet manufacturing: Based on the above step S1, after confirming the composition of the thin-walled high-pressure resistant seamless steel pipe, the prepared C, Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W components are placed in a casting furnace for billet manufacturing. When manufacturing the billet, the casting furnace is first heated to 1000-1500°C to melt the components, and the melting time is controlled to 1-2 hours. After the melting is completed, the casting furnace is first cooled to 600-700°C, and the cooled molten material is placed in a billet manufacturing mold. After cooling for 2-3 hours until the temperature reaches 300-400°C, the billet manufacturing is completed and it is transferred to the next step of manufacturing: S3: Centering processing: Based on the above step S2, the blank is transferred to the centering machine, and the blank is centered by the centering machine. During the centering process, the centering depth is controlled to be 1 / 4-1 / 3 of the blank length; S4: Perforation preparation: Based on the above step S3, the billet that has been centered is transferred to a roller cross-rolling piercing machine, and the billet is perforated by the roller cross-rolling piercing machine. During the perforation process, the billet is processed to 600-700°C, and the thickness of the steel pipe is controlled to 1 / 4-1 / 3 of the billet diameter. The billet is processed again to 800-900°C, and the thickness of the steel pipe is controlled to 1 / 6-1 / 5 of the billet diameter by the roller cross-rolling piercing machine. Finally, the billet is processed to 900-1000°C, and the thickness of the steel pipe is controlled to 1 / 8-1 / 7 of the billet diameter by the roller cross-rolling piercing machine; S5: Hole expansion and drawing: Based on the above step S4, the perforated steel pipe is transferred to the drawing pipe expansion unit, and the steel pipe is expanded and drawn again using a small variable multiple expansion and drawing method. The amount of each expansion and drawing is controlled to 1 / 10-1 / 12 of the thickness of the steel pipe. During this process, the temperature environment is 600-650℃. S6: Tempering treatment: Based on the above step S5, the steel pipe after hole expansion and drawing is tempered again, that is, the steel pipe is placed at a normalizing temperature of 600-900℃ for normalizing heat treatment, and then accelerated cooling is performed at an average cooling rate of 20-80℃ / s until the cooling stop temperature reaches below 350℃, thereby completing the manufacture of thin-walled high-pressure resistant seamless steel pipe.

2. The method for manufacturing a thin-walled high-pressure resistant seamless steel pipe according to claim 1, characterized in that: In step S1, the main components are C 25-30%, Si 5-10%, Mn 10-12%, P 5-8%, S 5-10%, Al 10-15%, Cu 5-7%, Ni 5-10%, Mo 10-20%, C 5-10% and W 5-10%.

3. The method for manufacturing a thin-walled, high-pressure resistant seamless steel pipe according to claim 1, characterized in that: In step S2, when manufacturing the blank, C is first placed in a casting furnace and heated to 1000-1200°C. After casting for 30-50 minutes, a mixture of Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W is added to the casting furnace and heated to 1200-1500°C.

4. The method for manufacturing a thin-walled high-pressure resistant seamless steel pipe according to claim 3, characterized in that: The Si, Mn, P, S, Al, Cu, Ni, Mo, Cr and W mixture is mixed by a mixer, specifically a JDC350 automatic mixer, and during mixing and stirring, the rotation speed is controlled at 800-1000 r / min, and the mixing and stirring time is controlled at 10-15 min.

5. The method for manufacturing a thin-walled high-pressure resistant seamless steel pipe according to claim 1, characterized in that: In step S3, the centering machine is specifically a 600SBRZ crankshaft centering machine, and when performing the centering process, the blank surface is centered using an optical centering method.

6. The method for manufacturing a thin-walled high-pressure resistant seamless steel pipe according to claim 1, characterized in that: In step S4, the roller cross-rolling piercing machine is specifically a JB / T13124-2017 two-roller cross-rolling piercing machine. Before hole preparation, the blank needs to be tempered once, and during tempering, the tempering temperature is controlled at 400-500°C.

7. The method for manufacturing a thin-walled high-pressure resistant seamless steel pipe according to claim 1, characterized in that: In step S5, the pulling-type pipe expanding machine unit is a 100-ton pulling-type pipe expanding machine unit, and the specific model is LLJZ-4-1 continuous pulling-type pipe expanding machine unit.

8. The method for manufacturing a thin-walled high-pressure resistant seamless steel pipe according to claim 1, characterized in that: In step S6, after the tempering treatment, the steel pipe needs to be subjected to general inspection, namely, appearance inspection, crack inspection, strength inspection, stress inspection and tension inspection.

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