A high-performance guide plate for seamless steel pipe piercing process and its processing method

Abstract

This invention belongs to the field of seamless steel pipe piercing technology, and relates to a high-performance guide plate and its processing method for seamless steel pipe piercing. The guide plate includes a guide plate body and a double-layer cooling system. The guide plate body has a working surface, which is a double-curved surface. The height difference h between the A-curved surface and the B-curved surface satisfies h=(0.1-0.15)S with respect to the thickness S of the guide plate compression band. The width c of the transition arc length of the B-curved surface satisfies c=(0.1-0.15)D with respect to the width D of the guide plate compression band. The cooling system includes a cooling tank located at the transition between the A-curved surface and the B-curved surface in the axial direction of the guide plate, and cooling water pipes with varying diameters installed in the cooling tank. By designing the working surface of the guide plate as a double-curved transition between the A-curved surface and the B-curved surface, the movement trajectory of the steel billet is more closely fitted with the guide plate. Combined with the guide plate structure where the A-curved surface and the B-curved surface are located, a double-layer cooling cross-flow arrangement structure is formed, which significantly improves the quality of the steel pipe, reduces the external surface defect rate generated in the piercing process by 30%, significantly improves the surface finish, and increases the service life of the guide plate.

Description

Technical Field

[0001] This invention belongs to the field of seamless steel pipe piercing technology, and relates to a high-performance guide plate for seamless steel pipe piercing process and its processing method. Background Technology

[0002] In existing seamless steel pipe production, piercing is one of the key processes, its main function being to process heated solid steel billets into hollow tubes. In the piercing mill, the guide plate is a core component ensuring the stable entry of the steel billet into the rolls and forming the cavity. However, existing traditional guide plates have the following drawbacks:

[0003] (1) Rapid surface wear: Due to the stationary state of the guide plate during the piercing process, there is intense friction between the high-temperature steel billet and the guide plate during the rolling deformation process, which makes the guide plate easy to wear and results in a short service life.

[0004] (2) Low cooling efficiency: When used on site, the guide plate is installed between two symmetrical perforated rollers. The space inside the perforated hole is compact. The cooling hole arrangement of the traditional guide plate is not ideal, resulting in limited surface heat dissipation capacity and easy to cause the guide plate to overheat and wear severely.

[0005] (3) Steel pipe surface quality problems: Improper design of the guide plate may cause scratches or other defects in the billet during the piercing process. Due to the limited heat dissipation capacity of its traditional guide plate cooling system, the surface temperature of the guide plate is very likely to cause "nodules", which affects the surface quality of the tube.

[0006] Therefore, it is of great significance to develop a high-performance guide plate to solve the above problems and improve perforation efficiency and product quality. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-performance guide plate and its processing method for seamless steel pipe piercing process. By designing the working surface of the guide plate as a hyperboloid transition between the A arc surface (entry section) and the B arc surface (exit section), the movement trajectory of the steel billet is more closely fitted with the guide plate, reducing local wear caused by uneven friction. Furthermore, the guide plate structure containing the A and B arc surfaces forms a double-layer cooling cross-flow arrangement structure, which optimizes cooling, significantly improves the quality of the steel pipe, reduces the external surface defect rate generated in the piercing process by 30%, significantly improves the surface finish, and greatly extends the service life of the guide plate.

[0008] The technical solution adopted by this invention to solve the technical problem is:

[0009] This invention discloses a high-performance guide plate for the piercing process of seamless steel pipes, comprising:

[0010] The guide plate body has a working surface, which is a double-arc curved surface, including an A-arc surface and a B-arc surface. The height difference h between the A-arc surface and the B-arc surface and the thickness S of the guide plate compression band satisfy h=(0.1-0.15)S, and the width c of the transition arc length of the B-arc surface and the width D of the guide plate compression band satisfy c=(0.1-0.15)D.

[0011] The cooling system includes a cooling tank located at the transition between arc surfaces A and B in the axial direction of the guide plate, and cooling water pipes with varying diameters installed in the cooling tank. The cooling water pipes are of diameter R1 at the L1 section from the inlet, and of diameter R2 at the remaining section, where R1 < R2.

[0012] Furthermore, the cooling water pipe is provided with water holes along the axial direction, with the diameter of the water holes increasing from the inlet end to the outlet end, and the hole spacing decreasing from the large end to the small end. The diameter of the water holes in section L1 is selected as 6~8mm, and the hole spacing is 15~20mm; the diameter of the water holes in section L2 is selected as 12~17mm, and the hole spacing is 8~12mm. More preferably, the diameter of the water holes in section L1 is 8mm and the hole spacing is 20mm; the diameter of the water holes in section L2 is 15mm and the hole spacing is 10mm, ensuring that the cooling effect of the outlet section is better than that of the inlet section.

[0013] Another aspect of the present invention discloses a method for processing a high-performance guide plate for a seamless steel pipe piercing process, comprising:

[0014] (1) The guide plate body is obtained by casting alloy steel. The chemical composition and content of the alloy steel are: C 0.55~0.75wt%, Si ≤1.5wt%, Mn ≤1.5wt%, Ni 48~50wt%, Cr 27~29wt%, W 3~5wt%, and the remainder is Fe. The surface hardness of the guide plate is 220~250HBW, and the hardness uniformity of the guide plate is ≤30HBW.

[0015] (2) An integral working surface is machined on the upper surface of the guide plate body. The working surface adopts an A-arc surface and a B-arc surface transition design. The height difference h between the A-arc surface and the B-arc surface and the thickness S of the guide plate compression strip satisfy h=(0.1-0.15)S, and the width c of the transition arc of the B-arc surface and the width D of the guide plate compression strip satisfy c=(0.1-0.15)D.

[0016] (3) A cooling trough is arranged at the transition between the A and B arc surfaces in the axial direction of the guide plate. Cooling water pipes with varying diameters are installed in the cooling trough. The section L1 from the inlet uses a water pipe with a diameter of R1, and the rest uses a water pipe with a diameter of R2. R1 < R2. The length of the L1 section corresponds to the length of the inlet cone of the guide plate.

[0017] (4) Plasma spraying ceramic coating is performed on the working surface A and the working surface B to obtain a high-performance guide plate.

[0018] Furthermore, the water flow pressure is increased at the steel-adhering section of the cooling water pipe to enhance cooling capacity. Dense cooling holes are set on the surface of the cooling water pipe in the high-friction area. The cooling water pipe is perforated along the axial direction, with the hole diameter increasing from small to large and the hole spacing decreasing from large to small from the inlet to the outlet. Its cooling area and cooling capacity match the steel billet deformation process, rationally distributing and improving the cooling capacity of the cooling water pipe, ensuring the uniformity of the guide plate surface temperature after cooling. The cooling water sprayed from the cooling holes is sprayed onto arc surfaces A and B respectively. Due to the different heights and curvatures of arc surfaces A and B, the cooling water is arranged in a staggered flow pattern. The guide plate structure containing arc surfaces A and B forms a double-layered cooling staggered flow arrangement, ensuring the steel billet rolling gap. The cooling pipe can cool the guide plate surface to the optimal working temperature, improving cooling efficiency and preventing high-temperature damage to the guide plate surface, thus extending the service life of the guide plate.

[0019] Furthermore, a lubricating oil channel interface is added to the tail of the guide plate to further reduce the friction coefficient between the billet and the guide plate. The lubricating oil channel interface at the tail of the guide plate is connected to the on-site lubrication system, which can be set to perform timed lubricating oil spraying on the surface of the guide plate, ensuring that the wear of the billet on the surface of the guide plate is reduced after spraying, thus reducing the amount of wear.

[0020] Furthermore, by using the diameter of the rolled billet and the outer diameter of the produced tube, the curvature of the A-curve and B-curve of the guide plate is calculated using the traditional guide plate design method. Combined with the cooling tank design, the curvature of the upper and lower parts of the cooling water pipe is optimized to form a double-curved surface, namely the inlet curvature and the outlet curvature. This makes the steel billet fit better with the guide plate surface during the piercing deformation process, the guide plate has a larger force-bearing area, and the wear is more uniform.

[0021] Furthermore, the guide plate adopts a modular design, facilitating quick replacement and maintenance. The guide plate is replaced and installed as a whole. After the guide plate is installed, the central cooling water pipe is fixed. The water pipe groove and positioning are pre-machined in the center of the guide plate to ensure that the direction of the water pipe holes is consistent with the design after installation, reducing manual adjustment time and improving replacement efficiency.

[0022] Furthermore, plasma-sprayed ceramic coatings (SigraFlexHT series from Schunk Carbon Technology) are applied to enhance wear resistance and thermal fatigue resistance.

[0023] The advantages and positive effects of this invention are:

[0024] (1) Excellent cooling performance: The cooling holes of the cooling water pipe and the guide plate structure where the A and B arc surfaces are located form a double-layer cooling cross-flow arrangement structure, which effectively improves the cooling efficiency, ensures the stable working temperature of the guide plate, and improves the service life of the guide plate.

[0025] (2) Improved steel pipe quality: The double arc surface design reduces the friction on the surface of the steel billet and reduces the occurrence of scratches and defects on the outer surface of the tube.

[0026] (3) High wear resistance: The working surface of the guide plate is coated with ceramic spray, which significantly reduces the wear rate of the guide plate and extends its service life.

[0027] (4) Significant economic benefits: The extended lifespan of the guide plate reduces the frequency of replacement and lowers downtime maintenance costs; the improved surface quality of the steel pipe reduces subsequent grinding costs and lowers production costs. Attached Figure Description

[0028] Figure 1 This is a top view of the guide plate of the present invention;

[0029] Figure 2 For the present invention Figure 1 A schematic diagram of the guide plate along direction AA is shown.

[0030] Figure 3 For the present invention Figure 1 A schematic diagram of the guide plate in the DD direction shown;

[0031] Figure 4 This is a physical diagram of the cooling water pipes and guide plate arrangement of the present invention.

[0032] Figure 5 This is a picture of a traditional integrated guide plate without a cooling water pipe in the middle. Detailed Implementation

[0033] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0034] Example 1

[0035] A method for processing a high-performance guide plate for a seamless steel pipe piercing process includes:

[0036] (1) The guide plate body is obtained by casting alloy steel. The chemical composition and content of the alloy steel are: C 0.75wt%, Si 1.2wt%, Mn 1.1wt%, Ni 50wt%, Cr 29wt%, W 5wt%, and the remainder is Fe. The surface hardness of the guide plate is 230HBW and the hardness uniformity of the guide plate is 30HBW.

[0037] (2) An integral working surface is machined on the upper surface of the guide plate body. The working surface adopts an A-arc surface and a B-arc surface transition design. The height difference h between the A-arc surface and the B-arc surface and the thickness S of the guide plate compression strip satisfy h=(0.1-0.15)S, and the width c of the transition arc of the B-arc surface and the width D of the guide plate compression strip satisfy c=(0.1-0.15)D.

[0038] (3) A cooling trough is arranged at the transition between the A and B arc surfaces in the axial direction of the guide plate. Cooling water pipes with varying diameters are installed in the cooling trough. The section L1 from the inlet uses R1 diameter water pipes, and the remaining section uses R2 diameter water pipes, where R1 < R2. The length of the L1 section corresponds to the length of the inlet cone of the guide plate. The water pressure is increased at the steel-adhering part of the cooling water pipe to improve the cooling capacity. Dense cooling holes are set on the surface of the cooling water pipe in the high-friction area. The cooling water pipe is perforated along the axial direction. The diameter of the water holes increases from small to large and the hole spacing decreases from large to small from the inlet end to the outlet end. Its cooling area and cooling capacity are consistent with the deformation process of the steel billet. The cooling capacity of the cooling water pipe is reasonably distributed and improved, ensuring the uniformity of the surface temperature of the guide plate after cooling.

[0039] A lubricating oil channel interface is added to the tail of the guide plate to further reduce the friction coefficient between the billet and the guide plate. The lubricating oil channel interface at the tail of the guide plate is connected to the on-site lubrication system, which can be set to perform timed lubricating oil spraying on the surface of the guide plate, ensuring that the billet wears less on the surface of the guide plate after spraying, thus reducing the amount of wear.

[0040] The curvature of the A and B arc surfaces of the guide plate is calculated by the diameter of the rolled billet and the outer diameter of the produced tube. Combined with the design of the cooling tank, the curvature of the upper and lower parts of the cooling water pipe is optimized to form a double-curved surface, namely the inlet curvature and the outlet curvature. This makes the steel billet fit better with the surface of the guide plate during the piercing deformation process, the force-bearing area of ​​the guide plate is larger, and the wear is more uniform.

[0041] (4) Apply a plasma-sprayed ceramic coating (SigraFlexHT series from Schunk Carbon Technology) to the working surfaces A and B to enhance wear resistance and thermal fatigue resistance.

[0042] A top view of the machined guide plate is shown below. Figure 1 As shown; a schematic diagram of the guide plate in direction AA is shown below. Figure 2 As shown; the schematic diagram of the guide plate in the DD direction is as follows. Figure 3 As shown in the diagram, the actual layout of the guide plate cooling water pipes and guide plate is as follows: Figure 4 As shown.

[0043] Example 2

[0044] A high-performance guide plate processed by the processing method described in Embodiment 1 includes: a guide plate body and a cooling system. The guide plate body has a working surface, which is a double-arc curved surface, including an A-arc surface and a B-arc surface, wherein the height difference between the A-arc surface and the B-arc surface is h=5cm, and the transition arc length width of the B-arc surface is c=25cm.

[0045] The cooling system includes a cooling trough located at the transition between arc surfaces A and B in the axial direction of the guide plate, and cooling water pipes with varying diameters installed within the cooling trough, the diameter of which gradually increases from the inlet to the outlet. Water holes are provided along the axial direction of the cooling water pipes; the diameter of the water holes in section L1 is 8cm with a spacing of 20cm, and the diameter of the water holes in section L2 is 15cm with a spacing of 10cm.

[0046] How to use the guide plate:

[0047] During the piercing deformation process, the billet moves forward spirally by rotating the A and B arc surfaces of the guide plate. Because the A and B arc surfaces are designed as double arc surfaces, they better match the actual spiral movement trajectory of the billet compared to traditional guide plate arc surfaces, reducing the local stress on the guide plate and making the stress on the entire working surface of the guide plate more uniform. Secondly, the cooling water pipes at the transition between the A and B arc surfaces can efficiently cool the surface of the guide plate after the work is completed. The density and diameter of the cooling water holes are arranged differently according to the axial stress trend of the guide plate (the inlet L1 uses a water pipe with a diameter of R1, and the remaining lengths use water pipes with a diameter of R2, where R1 < R2). The part of the guide plate where the A and B arc surfaces are located forms a double-layer cooling cross-flow arrangement structure, which ensures the billet rolling gap and allows the cooling pipes to cool the surface of the guide plate to the optimal working temperature.

[0048] Performance testing

[0049] The guide plate of this invention underwent performance testing in actual use, and compared with traditional guide plates. The relevant results are as follows:

[0050] Guide plate life: A 139.7*12.7mm specification bushing of 140V steel grade was selected for testing. The life of the guide plate of the present invention is more than 40% longer than that of the traditional guide plate. The number of steel billets that can be pierced by a single guide plate is increased from 900 pieces of the traditional guide plate to 1300 pieces.

[0051] Cooling effect: Offline temperature measurement was conducted on the surface of four sets of guide plates of the present invention (rolled to 300, 500, 800, and 1000 rolls) and four sets of conventional guide plates during their service life. The surface temperature of the guide plates of the present invention remained stable below 150°C, and the temperature difference between each friction area was ≤30°C, avoiding abnormal wear and melting of the guide plates caused by local overheating. In contrast, the surface temperature of the conventional guide plates began to be uneven when processing 800 rolls, and the temperature was higher, above 200°C, with a temperature difference between each friction area ≥50°C, resulting in a significant decrease in cooling efficiency.

[0052] Finished product quality: A test was conducted on a 140V grade 139.7*12.7mm sleeve. Using a traditional guide plate, 900 sleeves were rolled, but due to "nodules" on the guide plate, 281 sleeves were scrapped due to spiral scratches on the outer surface of the tube. Using the guide plate of this invention, 1300 sleeves were rolled with virtually no spiral outer surface defects caused by the piercing process. The outer surface defect rate caused by the piercing process was reduced by 30%, significantly improving the surface finish of the steel tube.

[0053] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. A high-performance guide plate for the piercing process of seamless steel pipes, characterized in that, include: The guide plate body has a working surface, which is a double-arc curved surface, including an A-arc surface and a B-arc surface. The height difference h between the A-arc surface and the B-arc surface and the thickness S of the guide plate compression band satisfy h=(0.1-0.15)S, and the width c of the transition arc length of the B-arc surface and the width D of the guide plate compression band satisfy c=(0.1-0.15)D. The cooling system includes a cooling tank located at the transition between arc surfaces A and B in the axial direction of the guide plate, and cooling water pipes with varying diameters installed in the cooling tank. The cooling water pipes at the L1 section from the inlet use R1 diameter pipes, while the remaining sections use R2 diameter pipes, where R1 < R2. Water holes are provided on the surface of the cooling water pipes along the axial direction from the inlet end to the outlet end, with the diameter of the water holes increasing from the inlet end to the outlet end and the hole spacing decreasing from the large end to the small end.

2. The high-performance guide plate according to claim 1, characterized in that, A lubricating oil channel interface is installed at the tail of the guide plate, and the lubricating oil channel interface is connected to the field lubricating oil system.

3. The high-performance guide plate according to claim 1, characterized in that, The guide plate is installed in a modular manner.

4. The high-performance guide plate according to claim 1, characterized in that, The cooling water pipe is fixed by a pipe clamp.

5. The processing method of the high-performance guide plate for seamless steel pipe piercing process as described in any one of claims 1 to 4, characterized in that, include: (1) The guide plate body is obtained by casting alloy steel. The chemical composition and content of the alloy steel are: C 0.55~0.75wt%, Si ≤1.5wt%, Mn ≤1.5wt%, Ni 48~50wt%, Cr 27~29wt%, W 3~5wt%, and the remainder is Fe; (2) An integral working surface is machined on the upper surface of the guide plate body. The working surface adopts an A-arc surface and a B-arc surface transition design. The height difference h between the A-arc surface and the B-arc surface and the thickness S of the guide plate compression strip satisfy h=(0.1-0.15)S, and the width c of the transition arc of the B-arc surface and the width D of the guide plate compression strip satisfy c=(0.1-0.15)D. (3) A cooling groove is machined at the transition between the A arc surface and the B arc surface in the axial direction of the guide plate. Cooling water pipes with varying diameters are installed in the cooling groove. The section from the inlet L1 uses a water pipe with a diameter of R1, and the rest uses a water pipe with a diameter of R2, where R1 < R2. (4) A ceramic coating is plasma sprayed onto the A arc surface and the B arc surface to obtain a high-performance guide plate.

6. The processing method according to claim 5, characterized in that, The surface hardness of the guide plate is 220~250HBW, and the hardness uniformity of the guide plate is ≤30HBW.

7. The processing method according to claim 5, characterized in that, The curvature of arc surfaces A and B is calculated based on the diameter of the rolled billet and the outer diameter of the tube.

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