Processing method of high temperature metal hard seal butterfly valve

Abstract

A high-temperature metal hard-sealed butterfly valve and a processing method thereof, the high-temperature metal hard-sealed butterfly valve comprises a valve body unit, a valve plate unit installed in the valve body unit, and a valve shaft unit capable of rotating the valve plate unit; the axial direction of the valve body unit is the X direction, the extension direction of the valve shaft unit is the Y direction, and a radial direction of the valve body unit perpendicular to the X direction and the Y direction is the Z direction; the valve body unit has a hollow valve body and a valve seat extending inward from the valve body; the valve plate unit has a valve plate sealed with the valve seat; the extension direction of the valve seat and the Z direction form a first angle, and when the valve plate unit is in a sealing position relative to the valve body unit, the extension direction of the valve plate unit and the Z direction form a second angle. The processing method of the high-temperature metal hard-sealed butterfly valve can manufacture the high-temperature metal hard-sealed butterfly valve.

Description

Technical Field

[0001] The invention relates to a processing technology of a butterfly valve, in particular to a processing method of a high-temperature metal hard-sealed butterfly valve. Background Art

[0002] In recent years, my country's power industry, aerospace, petroleum, and chemical industries have developed rapidly and maintained a momentum of sustained development. At present, high parameters of equipment have become a general trend. Taking the catalytic cracking unit as an example, a high-temperature metal hard-sealed butterfly valve is required. The medium is gas and solid. The gas is nitrogen, CO, oxygen, etc. The solid is mainly dust, less than 80PPm, and the particle size is ≤10μm. Under normal operating conditions, the temperature is at 650℃~670℃ for a long time, and can reach up to 800℃, the time does not exceed 15 minutes, about 6 times a year.

[0003] Whether it is a hydrogenation unit, a catalytic cracking unit or a supercritical thermal power generation unit, the use of high-temperature valves has always been very large. For products designed and developed specifically for high-temperature working conditions such as the flue gas system of a catalytic cracking unit, the main function of the high-temperature metal hard-sealed butterfly valve is to achieve the on-off and regulation of pipeline media under high-temperature working conditions. How to maintain the function of the high-temperature metal hard-sealed butterfly valve for a long time is a major challenge facing this field. Summary of the invention

[0004] The object of the present invention is to provide a high-temperature metal hard-sealed butterfly valve which can maintain the function of the butterfly valve at high temperature and can be used for a long time.

[0005] The technical solution adopted by the present invention to solve its technical problems is as follows: the high-temperature metal hard-sealed butterfly valve of the present invention comprises a valve body unit, a valve plate unit installed in the valve body unit, and a valve shaft unit capable of rotating the valve plate unit; the axial direction of the valve body unit is the X direction, the extending direction of the valve shaft unit is the Y direction, and a radial direction of the valve body unit and perpendicular to the X direction and the Y direction is the Z direction; the valve body unit comprises a hollow valve body on which the valve plate unit is rotatably installed, a valve seat extending inwardly from the valve body, and a valve body having a plurality of inner and outer surfaces. The valve body has a mounting portion extending outwardly along the Y direction; the valve plate unit can be located in a sealing position relative to the valve body unit, and the valve plate unit has a valve plate sealingly connected to the valve seat, a connecting rod portion connected to the valve shaft unit, and a connecting portion connecting the valve plate and the connecting rod portion; on an XZ plane perpendicular to the Y direction, an extension direction of the valve seat and the Z direction form a first angle; when the valve plate unit is located in the sealing position, on the XZ plane, an extension direction of the valve plate unit and the Z direction form a second angle that is the same as the first angle.

[0006] The high-temperature metal hard-sealed butterfly valve of the present invention is further configured as follows: a first metal layer is overlaid on the inner surface of the valve seat, and a valve plate sealing surface seal-connected to the valve seat is provided on the side of the valve plate adjacent to the valve seat; the angle between the extension directions of two lines of the valve plate sealing surface projected on the XZ plane is 18 to 40 degrees; the valve plate sealing surface is composed of a second metal layer overlaid with a hardness difference with the first metal layer; the valve seat has a sealing surface seal-connected to the valve plate unit; on the XZ plane, the sealing surface is an oblique line, and the angle between the sealing surface and the X direction is 0 to 5 degrees; the hardness difference between the valve seat and the valve plate sealing surface is ≥HRC5.

[0007] The high temperature metal hard seal butterfly valve of the present invention is further configured as follows: the first metal layer welded on the inner surface of the valve body is STL12 hard alloy, and the second metal layer welded on the valve plate sealing surface of the valve plate is STL6 hard alloy.

[0008] The high temperature metal hard seal butterfly valve of the present invention is further configured such that the angle between the extension direction of each line projected on the XZ plane by the valve plate sealing surface and the axial direction of the valve plate unit is 9 to 20 degrees.

[0009] The high-temperature metal hard-sealed butterfly valve of the present invention is further configured as follows: the valve shaft unit has a valve shaft that penetrates into the connecting rod portion and the mounting portion, and a transmission portion that connects to the actuator and transmits the valve shaft, and a packing is provided between the valve shaft and the mounting portion; the valve shaft can be rotatably installed in the connecting rod portion and the mounting portion.

[0010] The high-temperature metal hard-sealed butterfly valve of the present invention is further configured as follows: the valve shaft and the valve plate are connected and driven by a flat key.

[0011] The processing method of the high-temperature metal hard-sealed butterfly valve of the present invention can manufacture the high-temperature metal hard-sealed butterfly valve as described above; the processing method includes the processing of obtaining the valve body unit and the processing of obtaining the valve plate unit, and the processing step of boring the shaft hole of the valve body unit and the valve plate unit.

[0012] The processing to obtain the valve body unit includes the following steps:

[0013] Step 1-1: Install the first slope plate on the rotary table of the first lathe, and lock it after self-centering positioning;

[0014] The first slope plate rotates about a first rotation center line;

[0015] Step 1-2: a valve body unit blank is offset calibrated according to the calculated qualified eccentricity and then pressed;

[0016] Step 1-3: turning the valve body unit embryo in multiple passes with small cutting depths so that the valve body unit embryo has a valve seat embryo;

[0017] The processing to obtain the valve plate unit includes the following steps:

[0018] Step 2-1: Install the second slope plate on the rotary table of the second lathe, and lock it after self-centering positioning; the second slope plate rotates around a second rotation center line;

[0019] Step 2-2: perform offset calibration on the valve plate stop disc according to the calculated qualified eccentricity and then press it; Step 2-3: install a valve plate unit embryo into the valve plate stop disc by using the stop positioning and tighten it; Step 2-4: rough turn the valve plate unit embryo so that the valve plate unit embryo has a valve plate embryo body;

[0020] Step 2-6: After clamping and positioning according to step 2-3, the valve plate blank is turned in multiple passes with small cuts, so that the valve plate blank can initially form a cone-to-cone sealing connection with the valve seat blank.

[0021] The processing method of the high-temperature metal hard-sealed butterfly valve of the present invention is further configured as follows: in step 1-1, the inclination disk of the first inclination plate forms an angle of 9 degrees with the horizontal direction; in step 1-2, the first rotation center line forms an angle of 9 degrees with the X direction; in step 1-3, the side of the valve seat embryo forms an angle of 5 degrees with the X direction and an angle of 14 degrees with the first rotation center line; in step 2-1, the inclination disk of the second inclination plate forms an angle of 9 degrees with the horizontal direction; in step 2-2, the second rotation center line forms an angle of 9 degrees with the X direction; in step 2-4, the valve plate embryo forms an angle of 14 degrees with the second rotation center line.

[0022] The processing method of the high temperature metal hard seal butterfly valve of the present invention is further configured as follows: the processing of obtaining the valve body unit further includes the following steps:

[0023] Step 1-4: Grinding the valve seat blank using an electric grinding head to form a sealing surface of the valve seat blank;

[0024] Step 1-5: Perform PT testing on the valve seat;

[0025] The processing of obtaining the valve plate unit also includes the following steps:

[0026] Step 2-5: performing surfacing welding on the valve plate embryo;

[0027] Step 2-7: Grinding the valve plate blank with an electric grinding head to form a base surface of the valve plate and a valve plate sealing surface, so that the valve plate and the valve seat form a cone-to-cone sealing connection;

[0028] Step 2-8: Perform PT testing on the valve plate;

[0029] The step 2-5 is after the step 2-4 and before the step 2-6.

[0030] The processing method of the high-temperature metal hard-sealed butterfly valve of the present invention is further configured as follows: the first slope plate and the second slope plate are the same or different slope plates, and the first lathe turntable and the second lathe turntable are also the same or different lathe turntables.

[0031] The beneficial effects of the present invention are: when the valve plate unit is located in the sealing position, the extension direction of the valve seat and the Z direction form a first angle; the extension direction of the valve plate unit and the Z direction form a second angle, which can effectively reduce the valve opening stroke range, reduce the seal wear, and extend the service life. The inclined structure makes the medium sealing force more conducive to auxiliary sealing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram, schematically illustrating the structure and relative position relationship of the valve body unit and the valve plate unit of the high-temperature metal hard-sealed butterfly valve of the present invention.

[0033] Figure 2 It is a schematic diagram, schematically illustrating the main components and relative positional relationship of the high-temperature metal hard-sealed butterfly valve of the present invention.

[0034] Figure 3 This is an enlarged schematic diagram, schematically illustrating Figure 2 The structure of the valve plate of the valve plate unit of the high-temperature metal hard-sealed butterfly valve of the present invention is shown in the middle circle.

[0035] Figure 4 It is a schematic diagram, schematically illustrating a processing method for obtaining a valve body unit in a processing method for a high-temperature metal hard-sealed butterfly valve of the present invention.

[0036] Figure 5 It is a schematic diagram, schematically illustrating a processing method for obtaining a valve plate unit in a processing method for a high-temperature metal hard-sealed butterfly valve of the present invention. DETAILED DESCRIPTION

[0037] In the following description, similar elements are represented by the same reference numerals, and directional terms, such as "X direction", "Y direction", "Z direction", etc., are only used to illustrate the relative positional relationship between elements and cannot be used to limit the technical scope of the present invention.

[0038] like Figure 1 , 2 As shown, the high temperature metal hard seal butterfly valve of the present invention comprises a valve body unit 1, a valve plate unit 2 installed in the valve body unit 1, and a valve shaft unit 3 capable of rotating the valve plate unit 2.

[0039] The axial direction of the valve body unit 1 is defined as an X direction, the extending direction of the valve shaft unit 3 is defined as a Y direction, and a radial direction of the valve body unit 1 that is perpendicular to the X direction and the Y direction is defined as a Z direction.

[0040] The valve body unit 1 comprises a hollow valve body 11 on which the valve plate unit 2 is rotatably mounted, a valve seat 12 integrally extending inward from the valve body 11, and a mounting portion 13 extending outward from the valve body 11 along the Y direction. A first metal layer is welded on the inner surface of the valve seat 12. On the XZ plane perpendicular to the Y direction, the extension direction of the valve seat 12 forms a first angle with the Z direction. Figure 3 As shown, the valve seat 12 has a valve seat side surface 121 adjacent to the valve plate unit 2 and a sealing surface 122 protruding from the valve seat side surface 121 and sealed to the valve plate unit 2. On the XZ plane, the sealing surface 122 is an oblique line, and its angle with the X direction is 0 to 5 degrees. The valve plate unit 2 can be located in a sealing position relative to the valve body unit 1. When the valve plate unit 2 is located in the sealing position, on the XZ plane, the extension direction of the valve plate unit 2 and the Z direction form a second angle equal to the first angle. For high temperature

[0041] It is a common problem for valves under working conditions to have a short service life. Therefore, the valve plate unit 2 is changed to an inclined structure, which effectively reduces the valve opening range (less than 90 degrees of opening and closing), reduces the seal wear, and prolongs the service life. The inclined structure makes the medium sealing force more conducive to auxiliary sealing. The technology of enabling the valve plate unit 2 to be rotatably installed in the valve body 11 is well known to those skilled in the art, and is not the focus of the present invention, so it will not be repeated here.

[0042] like Figure 2 , 3 As shown, the valve plate unit 2 has a valve plate 21 sealed with the valve seat 12, a connecting rod portion 22 connected to the valve shaft unit 3, and a connecting portion connecting the valve plate 21 and the connecting rod portion 22. The valve plate 21 has an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface, the side surface is adjacent to the valve seat 12 and has a base surface 211 opposite to the valve seat 12 and a valve plate sealing surface 212 protruding from the base surface 211 and sealed with the valve seat 12. The valve plate sealing surface 212 is composed of a second metal layer with a hardness difference with the first metal layer by surfacing welding, and the angle between the extension directions of the two lines of the valve plate sealing surface 212 projected on the XZ plane is 18 to 40 degrees. In an alternative embodiment, the angle between the extension direction of each line of the valve plate sealing surface 212 projected on the XZ plane and the axial direction of the valve plate unit 2 is 9 to 20 degrees. Each connecting rod portion 22 is provided for the valve shaft unit 3 to pass through.

[0043] The valve plate unit 2 adopts a three-dimensional eccentric inclined conical valve seat structure. Unlike the general sealing butterfly valve, its valve plate is inclined relative to the valve body. When the high-temperature metal hard-sealed butterfly valve is opened and closed, the seal is disengaged when it is opened and sealed when it is closed. The relative friction between the valve plate and the valve seat within the full rotation range of 90° of the valve is completely eliminated, and a satisfactory sealing effect can be obtained without relying on the elastic deformation of the metal sealing ring.

[0044] Since there are no elastic metal sealing rings, sealing ring pressure plates and bolts, the sealing is completely based on the metal hard sealing structure of the valve plate and the valve seat, eliminating the potential safety hazard of fasteners falling off and entering the gas turbine, making it safer and more reliable to use.

[0045] In order to ensure a good sealing effect, a larger sealing pressure ratio is required than that of a soft seal or a combination of a soft and hard seal. That is, when the valve plate unit 2 is about to reach the closed position, the actuator needs to apply a large torque to squeeze the valve plate 21 of the valve plate unit 2 into the valve seat. To ensure good sealing performance under long-term operation, the hardness of the valve plate 21 must be guaranteed. In an alternative implementation, the first metal layer welded on the inner surface of the valve body 11 is STL12 hard alloy, and the second metal layer welded on the valve plate sealing surface 212 of the valve plate 21 is STL6 hard alloy, which not only has a strong hardness, but also has a hardness difference between the two. The Stellite material has good thermal strength at high temperatures and a longer service life.

[0046] In order to improve the anti-scouring performance, the sealing surface is hardened and welded with cemented carbide. The hardness difference between the valve seat and the valve plate sealing surface is ≥HRC5, ensuring the wear resistance, reliability and good anti-scouring performance of the seal.

[0047] The valve shaft unit 3 has a valve shaft 31 that penetrates the connecting rod portion 22 and the mounting portion 13, and a transmission portion 32 that connects the actuator and transmits the valve shaft 31. A packing and a packing gland are provided between the valve shaft 31 and the mounting portion 13. The valve shaft 31 can be rotatably installed in the connecting rod portion 22 and the mounting portion 13. In order to improve the reliability of the valve under high temperature conditions, the valve shaft 13 and the valve plate 21 are connected and transmitted by a flat key, which effectively prevents the valve shaft from elongating under high temperature conditions and affecting the sealing performance of the valve. The structure of the valve shaft unit 3 is a technology well known to those skilled in the art, and is not the focus of improvement of the present invention, so it will not be repeated here.

[0048] The high-temperature metal hard-sealed butterfly valve of the present invention has a valve plate that is tilted relative to the valve body. When the butterfly valve is opened and closed, the seal is released when it is opened, and sealed when it is closed. The sealing pair adopts a metal hard sealing structure without a metal sealing ring. The two maintain a reasonable hardness difference, and a satisfactory sealing effect can be obtained. The overall sealing performance is reliable, can achieve zero leakage of the seal, and can also withstand high temperatures, with a maximum operating temperature of up to 700°C.

[0049] The following is an explanation of the processing method of the high-temperature metal hard-sealed butterfly valve of the present invention.

[0050] The processing method comprises the steps of obtaining a valve body unit and a valve plate unit, and performing a combined boring shaft hole processing step on the valve body unit and the valve plate unit.

[0051] like Figure 4 As shown, the processing of obtaining the valve body unit 1 includes the following steps:

[0052] Step 1-1: Install the first inclination plate 03 on the first lathe rotary table 04, and lock it after self-centering. The first inclination plate 03 rotates around a first rotation center line. In an alternative embodiment, the inclination plate of the first inclination plate 03 forms an angle of 9 degrees with the horizontal direction.

[0053] Step 1-2: A valve body unit blank is offset-calibrated according to the calculated qualified eccentricity and then pressed. In an alternative implementation, the first rotation center line and the X direction form an angle of 9 degrees.

[0054] Step 1-3: lathe the valve body unit embryo in multiple passes with small cutting amounts so that the valve body unit embryo has a valve seat embryo. In an alternative implementation, the valve seat side of the valve seat embryo forms an angle of 5 degrees with the X direction and an angle of 14 degrees with the first rotation center line.

[0055] Step 1-4: Grinding the valve seat blank using an electric grinding head to form a sealing surface of the valve seat blank.

[0056] Step 1-5: Perform PT testing on the valve seat.

[0057] like Figure 5 As shown, the processing of obtaining the valve plate unit 2 includes the following steps:

[0058] Step 2-1: Install the second slope plate 03' on the second lathe rotary table 04', and lock it after self-centering; the second slope plate 03' rotates around a second rotation center line. In an alternative embodiment, the slope plate of the second slope plate 03' forms an angle of 9 degrees with the horizontal direction.

[0059] Step 2-2: The valve plate stop plate 02 is offset-calibrated according to the calculated qualified eccentricity and then pressed. In an alternative implementation, the second rotation center line and the X direction form an angle of 9 degrees.

[0060] Step 2-3: A valve plate unit embryo is positioned by using the stopper to install it into the valve plate stopper disc 02 and tighten it.

[0061] Step 2-4: Rough-machine the valve plate unit embryo so that the valve plate unit embryo has a valve plate embryo body. In an alternative implementation, each projection line of the side surface of the valve plate embryo body on the XZ plane forms an angle of 14 degrees with the second rotation center line.

[0062] Step 2-5: performing a surfacing treatment on the valve plate embryo.

[0063] Step 2-6: After clamping and positioning according to step 2-3, the valve plate blank is turned in multiple passes with small cuts, so that the valve plate blank can initially form a cone-to-cone sealing connection with the valve seat blank.

[0064] Step 2-7: Grinding the valve plate blank with an electric grinding head to form a base surface and a valve plate sealing surface of the valve plate, so that the valve plate and the valve seat form a cone-to-cone sealing connection.

[0065] Step 2-8: Perform PT testing on the valve plate.

[0066] In a specific implementation process, the first slope plate 03 and the second slope plate 03' can be the same or different slope plates, and the first lathe turntable 04 and the second lathe turntable 04' can also be the same or different lathe turntables.

[0067] The processing method of the high-temperature metal hard-sealed butterfly valve of the present invention can ensure that the processed high-temperature metal hard-sealed butterfly valve has a reasonable structure, especially ensure the sealing performance under high temperature and the service life requirement under long-term operation.

[0068] The above is only a preferred embodiment of the present invention and cannot be used to limit the technical scope of the present invention. Any simple equivalent changes made in accordance with the claims and description of the present invention belong to the scope of the present invention.

Claims

1. A processing method for a high-temperature metal hard-sealed butterfly valve, the butterfly valve comprising a valve body unit, a valve plate unit installed in the valve body unit, and a valve shaft unit capable of rotating the valve plate unit; the axial direction of the valve body unit is the X direction, the extending direction of the valve shaft unit is the Y direction, and a radial direction of the valve body unit perpendicular to the X direction and the Y direction is the Z direction; the valve body unit comprises a hollow valve body on which the valve plate unit is rotatably installed, a valve seat extending inwardly from the valve body, and a mounting portion extending outwardly from the valve body along the Y direction; the valve plate unit can be located in a sealed position relative to the valve body unit, and the valve plate unit comprises a valve plate sealedly connected to the valve seat, a connecting rod portion connected to the valve shaft unit, and a connecting portion connecting the valve plate and the connecting rod portion; characterized in that: On the XZ plane perpendicular to the Y direction, the extension direction of the valve seat and the Z direction form a first angle; when the valve plate unit is located at the sealing position, on the XZ plane, the extension direction of the valve plate unit and the Z direction form a second angle that is the same as the first angle; The processing method includes processing to obtain a valve body unit and processing to obtain a valve plate unit, and performing combined boring of the valve body unit and the valve plate unit. The processing to obtain the valve body unit includes the following steps: Step 1-1: Install the first slope plate on the rotary table of the first lathe, and lock it after self-centering positioning; the first slope plate rotates around a first rotation center line; Step 1-2: a valve body unit blank is offset calibrated according to the calculated qualified eccentricity and then pressed; Step 1-3: turning the valve body unit embryo in multiple passes with small cutting depths so that the valve body unit embryo has a valve seat embryo; Step 1-4: Grinding the valve seat blank using an electric grinding head to form a sealing surface of the valve seat blank; Step 1-5: Perform PT testing on the valve seat; The processing to obtain the valve plate unit includes the following steps: Step 2-1: Install the second slope plate on the second lathe turntable and lock it by self-centering positioning; The second slope plate rotates around a second rotation center line; Step 2-2: The stop disc of the valve plate is offset calibrated according to the calculated qualified eccentricity and then tightened; Step 2-3: insert a valve plate unit embryo into the valve plate stop plate by using the stopper to position it and tighten it; Step 2-4: Roughly machining the valve plate unit embryo so that the valve plate unit embryo has a valve plate embryo body; Step 2-5: Performing surfacing treatment on the valve plate embryo; Step 2-6: after clamping and positioning according to step 2-3, lathe the valve plate embryo in multiple passes with small cuts, so that the valve plate embryo can initially form a cone-to-cone sealing connection with the valve seat embryo; Step 2-7: Grinding the valve plate blank with an electric grinding head to form a base surface of the valve plate and a valve plate sealing surface, so that the valve plate and the valve seat form a cone-to-cone sealing connection; Step 2-8: Perform PT inspection on the valve plate.

2. The processing method of the high temperature metal hard seal butterfly valve according to claim 1, characterized in that: The inner surface of the valve seat is welded with a first metal layer, and the side of the valve plate adjacent to the valve seat has a valve plate sealing surface sealed to the valve seat; the angle between the extension directions of two lines of the valve plate sealing surface projected on the XZ plane is 18 to 40 degrees; the valve plate sealing surface is composed of a second metal layer that is welded and has a hardness difference with the first metal layer; the valve seat has a sealing surface that is sealed to the valve plate unit; on the XZ plane, the sealing surface is an oblique line, and the angle between it and the X direction is 0 to 5 degrees; the hardness difference between the valve seat and the valve plate sealing surface is ≥HRC5.

3. The processing method of the high temperature metal hard seal butterfly valve according to claim 2, characterized in that: The first metal layer welded on the inner surface of the valve body is STL12 hard alloy, and the second metal layer welded on the valve plate sealing surface of the valve plate is STL6 hard alloy.

4. The processing method of the high temperature metal hard seal butterfly valve according to claim 2, characterized in that: The angle between the extending direction of each line of the valve plate sealing surface projected on the XZ plane and the axial direction of the valve plate unit is 9 to 20 degrees.

5. The processing method of a high temperature metal hard seal butterfly valve according to any one of claims 1 to 4, characterized in that: The valve shaft unit comprises a valve shaft which penetrates into the connecting rod part and the mounting part, and a transmission part which connects to the actuator and transmits the valve shaft, and a packing is arranged between the valve shaft and the mounting part; the valve shaft is rotatably mounted in the connecting rod part and the mounting part.

6. The method for processing a high temperature metal hard seal butterfly valve according to claim 5, characterized in that: The valve shaft and the valve plate are connected and driven by a flat key.

7. The processing method of the high temperature metal hard seal butterfly valve according to claim 1, characterized in that: In step 1-1, the inclination disk of the first inclination plate forms an angle of 9 degrees with the horizontal direction; in step 1-2, the first rotation center line forms an angle of 9 degrees with the X direction; in step 1-3, the side of the valve seat embryo forms an angle of 5 degrees with the X direction and an angle of 14 degrees with the first rotation center line; in step 2-1, the inclination disk of the second inclination plate forms an angle of 9 degrees with the horizontal direction; in step 2-2, the second rotation center line forms an angle of 9 degrees with the X direction; in step 2-4, the valve plate embryo forms an angle of 14 degrees with the second rotation center line.

8. The method for processing a high temperature metal hard seal butterfly valve according to any one of claims 1 to 7, characterized in that: The first slope plate and the second slope plate are the same or different slope plates, and the first lathe turntable and the second lathe turntable are also the same or different lathe turntables.

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