Polishing method for seamless steel pipe

Abstract

The polishing method comprises the following steps that S1, acid pickling is conducted, specifically, the steel pipe is subjected to acid pickling through an acid pickling solution, and impurities inside and outside the steel pipe are removed; s2, rough polishing is conducted, specifically, the inner face and the outer face of the steel pipe subjected to acid pickling are roughly polished on a polishing machine; s3, fine polishing is conducted, specifically, the steel pipe is put into a polishing solution to be soaked and then taken out, and a curing layer is formed on the surface of the steel pipe through the polishing solution; s4, cleaning: cleaning a cured layer on the surface of the steel pipe to obtain a polished seamless steel pipe; according to the polishing method of the seamless steel pipe, the mode that mechanical polishing and chemical polishing are combined is adopted, the defect that the internal precision of the seamless steel pipe is difficult to control through mechanical polishing can be overcome, the surface of the seamless steel pipe is smooth through mechanical polishing after the seamless steel pipe is pretreated through the pickling solution, and then the seamless steel pipe is finely polished through the polishing solution; and the polishing effect of consistent smoothness of the inner and outer surfaces is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel pipe polishing processing, and in particular relates to a polishing method for a seamless steel pipe. Background Art

[0002] Seamless steel pipes are used in medical, automotive, military and aviation fields. Some application fields have strict requirements on the smoothness of their inner and outer surfaces. Therefore, they need to be polished before leaving the factory to meet the supply requirements. At present, the common polishing methods for seamless steel pipes are mechanical polishing and chemical polishing; mechanical polishing has low processing costs and high surface brightness, but pure mechanical polishing is difficult to meet the supply quality requirements. Due to the special structure of the steel pipe, it is difficult to control the polishing accuracy inside it; chemical polishing is mainly used for workpieces with complex structures. Chemical polishing can polish workpieces with complex structures, and has low processing costs. The workpieces after chemical polishing have better corrosion resistance; currently, most steel pipes are polished by mechanical polishing, and pure mechanical polishing is difficult to meet the supply requirements. Therefore, a combination of mechanical polishing and chemical polishing is adopted to make the smoothness of the inner and outer surfaces of the steel pipe reach a higher level, and the production efficiency is high, which is suitable for batch processing. Summary of the invention

[0003] The purpose of the present invention is to provide a polishing method for seamless steel pipes, which can overcome the disadvantage that it is difficult to control the internal precision of seamless steel pipes by mechanical polishing. It adopts a combination of mechanical polishing and chemical polishing, uses pickling liquid to pre-treat it, then uses mechanical polishing to make its surface smooth, and then uses polishing liquid to fine-polish it, so as to achieve a polishing effect with consistent smoothness of the inner and outer surfaces.

[0004] The present invention is achieved through the following technical solutions: A polishing method for a seamless steel pipe comprises the following steps: S1: Pickling: pickling the steel pipe with pickling liquid to remove impurities inside and outside; S2: Rough polishing, the pickled steel pipe is roughly polished on both the inside and outside surfaces on a polishing machine; S3: Fine polishing: soak the steel pipe in the polishing liquid and then take it out, so that the polishing liquid forms a solidified layer on the surface of the steel pipe; S4: Cleaning, cleaning off the solidified layer on the surface of the steel pipe to obtain a polished seamless steel pipe.

[0005] Furthermore, in step S1, the component formula of the pickling solution is: 100 parts of water, 10-15 parts of hydrochloric acid, 5-10 parts of citric acid, 1-3 parts of nitric acid and 10-15 parts of emulsifier.

[0006] Furthermore, in step S1, the temperature of the pickling solution is controlled at 55°C-65°C.

[0007] Furthermore, in step S1, the pickling time of the steel pipe is: 12-16 minutes.

[0008] Furthermore, in step S2, the steel pipe is roughly polished so that the smoothness of its interior and surface reaches 4 or above.

[0009] Furthermore, in step S3, the polishing liquid has a component formula of: 100 parts of water, 15-20 parts of methacrylamide gelatin, 2-4 parts of nitric acid, 10-12 parts of hydrochloric acid, 5-10 parts of trifluoroacetic acid, 3-6 parts of thickener and 1 part of photosensitizer.

[0010] Furthermore, in step S3, the steel pipe is immersed in the polishing liquid for 30-45 minutes.

[0011] Furthermore, in step S3, the temperature of the polishing liquid is controlled at 2-5°C.

[0012] Furthermore, in step S3, the specific operation method of making the polishing liquid form a solidified layer on the surface of the steel pipe is: take the steel pipe out of the polishing liquid and place it vertically, wait for the polishing liquid on its surface to drain, use an ultraviolet lamp to irradiate the inside and outside of it for 30-60s, and wait for the polishing liquid on its surface to solidify to form a solidified layer.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1) In the polishing method of the seamless steel pipe of the present invention, a combination of mechanical polishing and chemical polishing is adopted, which can overcome the disadvantage that it is difficult to control the internal precision of the seamless steel pipe by mechanical polishing. After pre-treatment with pickling liquid, the surface is smoothed by mechanical polishing, and then fine-polishing with polishing liquid is performed to achieve a polishing effect with consistent smoothness of the inner and outer surfaces.

[0014] 2) In the polishing method of the seamless steel pipe of the present invention, the polishing effect of the seamless steel pipe is uniform and the polishing efficiency is high, the smoothness of the inner and outer surfaces of the seamless steel pipe can be kept consistent, and the seamless steel pipe will not be excessively damaged or thinned during the polishing process. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0016] Embodiment 1: A polishing method for a seamless steel pipe comprises the following steps: S1: Pickling: pickling the steel pipe with a pickling solution having a component formula of 100 parts of water, 10 parts of hydrochloric acid, 5 parts of citric acid, 1 part of nitric acid and 10 parts of emulsifier. The temperature of the pickling solution is 55°C. Pickling takes 12 minutes to remove impurities inside and outside the steel pipe. S2: Rough polishing: the pickled steel pipe is roughly polished on both the inside and outside of the polishing machine to make the surface and internal finish reach level 4 or above; S3: Fine polishing, immerse the steel pipe in a polishing liquid with the following components: 100 parts of water, 15 parts of methacrylamide gelatin, 2 parts of nitric acid, 10 parts of hydrochloric acid, 5 parts of trifluoroacetic acid, 3 parts of thickener and 1 part of photosensitizer, the temperature of the polishing liquid is 2°C, and take it out after soaking for 30 minutes; take the steel pipe out of the polishing liquid and place it vertically, wait for the polishing liquid on its surface to drain, use ultraviolet lamp to irradiate it inside and outside, the irradiation time is 30-60s, and wait for the polishing liquid on its surface to solidify to form a solidified layer; S4: Cleaning: cleaning the solidified layer on the surface of the steel pipe. Ultrasonic equipment or existing non-destructive cleaning equipment can be used to clean the steel pipe. After cleaning the solidified layer on the surface of the steel pipe, a polished seamless steel pipe is obtained.

[0017] After testing and judging according to relevant standards (GB 1031-83), the smoothness of the inner and outer surfaces of the seamless steel pipe polished in this embodiment reaches Grade 9.

[0018] Embodiment 2: A polishing method for a seamless steel pipe comprises the following steps: S1: pickling, pickling the steel pipe with a pickling solution having a component formula of 100 parts of water, 11 parts of hydrochloric acid, 6 parts of citric acid, 2 parts of nitric acid and 11 parts of emulsifier, the temperature of the pickling solution is 60°C, pickling for 14 minutes, to remove impurities inside and outside; S2: Rough polishing: the pickled steel pipe is roughly polished on both the inside and outside of the polishing machine to make the surface and internal finish reach level 4 or above; S3: Fine polishing, immerse the steel pipe in a polishing liquid with the following component formula: 100 parts of water, 16 parts of methacrylamide gelatin, 3 parts of nitric acid, 11 parts of hydrochloric acid, 6 parts of trifluoroacetic acid, 4 parts of thickener and 1 part of photosensitizer, the temperature of the polishing liquid is 3°C, and take it out after soaking for 35 minutes; take the steel pipe out of the polishing liquid and place it vertically, wait for the polishing liquid on its surface to drain, use ultraviolet lamp to irradiate it inside and outside, the irradiation time is 30-60s, and wait for the polishing liquid on its surface to solidify to form a solidified layer; S4: Cleaning: cleaning the solidified layer on the surface of the steel pipe. Ultrasonic equipment or existing non-destructive cleaning equipment can be used to clean the steel pipe. After cleaning the solidified layer on the surface of the steel pipe, a polished seamless steel pipe is obtained.

[0019] After testing and judging according to the relevant standard (GB 1031-83), the smoothness of the inner and outer surfaces of the seamless steel pipe polished in this embodiment is also grade 9.

[0020] Embodiment 3: A polishing method for a seamless steel pipe comprises the following steps: S1: Pickling: pickling the steel pipe with a pickling solution having a component formula of 100 parts of water, 13 parts of hydrochloric acid, 7 parts of citric acid, 3 parts of nitric acid and 14 parts of emulsifier. The temperature of the pickling solution is 60°C, and the pickling is performed for 16 minutes to remove impurities inside and outside the steel pipe. S2: Rough polishing: the pickled steel pipe is roughly polished on both the inner and outer surfaces on a polishing machine to make the surface and internal finish reach level 5 or above; S3: Fine polishing, immerse the steel pipe in a polishing liquid with the following components: 100 parts of water, 18 parts of methacrylamide gelatin, 3 parts of nitric acid, 11 parts of hydrochloric acid, 8 parts of trifluoroacetic acid, 5 parts of thickener and 1 part of photosensitizer, the temperature of the polishing liquid is 4°C, and take it out after soaking for 40 minutes; take the steel pipe out of the polishing liquid and place it vertically, wait for the polishing liquid on its surface to drain, use ultraviolet lamp to irradiate it inside and outside, the irradiation time is 30-60s, and wait for the polishing liquid on its surface to solidify to form a solidified layer; S4: Cleaning: cleaning the solidified layer on the surface of the steel pipe. Ultrasonic equipment or existing non-destructive cleaning equipment can be used to clean the steel pipe. After cleaning the solidified layer on the surface of the steel pipe, a polished seamless steel pipe is obtained.

[0021] After testing and judging according to the relevant standard (GB 1031-83), the smoothness of the inner and outer surfaces of the seamless steel pipe obtained by polishing in this embodiment is grade 10.

[0022] Embodiment 4: A polishing method for a seamless steel pipe comprises the following steps: S1: Pickling: pickling the steel pipe with a pickling solution having a component formula of 100 parts of water, 15 parts of hydrochloric acid, 10 parts of citric acid, 3 parts of nitric acid and 15 parts of emulsifier. The temperature of the pickling solution is 65°C. Pickling takes 16 minutes to remove impurities inside and outside the steel pipe. S2: Rough polishing: the pickled steel pipe is roughly polished on both the inner and outer surfaces on a polishing machine to make the surface and internal finish reach level 5 or above; S3: Fine polishing, immerse the steel pipe in a polishing liquid with the following component formula: 100 parts of water, 20 parts of methacrylamide gelatin, 4 parts of nitric acid, 12 parts of hydrochloric acid, 10 parts of trifluoroacetic acid, 6 parts of thickener and 1 part of photosensitizer, the temperature of the polishing liquid is 5°C, and take it out after soaking for 45 minutes; take the steel pipe out of the polishing liquid and place it vertically, wait for the polishing liquid on its surface to drain, use ultraviolet lamp to irradiate it inside and outside, the irradiation time is 30-60s, and wait for the polishing liquid on its surface to solidify to form a solidified layer; S4: Cleaning: cleaning the solidified layer on the surface of the steel pipe. Ultrasonic equipment or existing non-destructive cleaning equipment can be used to clean the steel pipe. After cleaning the solidified layer on the surface of the steel pipe, a polished seamless steel pipe is obtained.

[0023] After testing and judging according to the relevant standard (GB 1031-83), the smoothness of the inner and outer surfaces of the seamless steel pipe obtained by polishing in this embodiment is also level 10.

[0024] If the terms "horizontal" or "vertical" appear in the description of the present invention, it does not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A polishing method for a seamless steel pipe, characterized in that: The following steps are involved: S1: Pickling: pickling the steel pipe with pickling liquid to remove impurities inside and outside; S2: Rough polishing, the pickled steel pipe is roughly polished on both the inside and outside surfaces on a polishing machine; S3: Fine polishing: soak the steel pipe in the polishing liquid and then take it out, so that the polishing liquid forms a solidified layer on the surface of the steel pipe; S4: Cleaning, cleaning off the solidified layer on the surface of the steel pipe to obtain a polished seamless steel pipe.

2. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S1, the component formula of the pickling solution is: 100 parts of water, 10-15 parts of hydrochloric acid, 5-10 parts of citric acid, 1-3 parts of nitric acid and 10-15 parts of emulsifier.

3. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S1, the temperature of the pickling solution is controlled at 55°C-65°C.

4. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S1, the pickling time of the steel pipe is: 12-16 minutes.

5. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S2, the steel pipe is roughly polished to achieve a smoothness of 4 or above on the inside and the surface.

6. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S3, the polishing liquid has the following components: 100 parts of water, 15-20 parts of methacrylamide gelatin, 2-4 parts of nitric acid, 10-12 parts of hydrochloric acid, 5-10 parts of trifluoroacetic acid, 3-6 parts of thickener and 1 part of photosensitizer.

7. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S3, the steel pipe is immersed in the polishing liquid for 30-45 minutes.

8. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S3, the temperature of the polishing liquid is controlled at 2-5°C.

9. The method for polishing a seamless steel pipe according to claim 1, characterized in that: In step S3, the specific operation method of making the polishing liquid form a solidified layer on the surface of the steel pipe is: take the steel pipe out of the polishing liquid and place it vertically, wait for the polishing liquid on its surface to drain, use an ultraviolet lamp to irradiate the inside and outside of it for 30-60s, and wait for the polishing liquid on its surface to solidify to form a solidified layer.