Device and method for preparing diamond grinding wheel for polishing inner wall of ultra-slender pipe

Abstract

The invention discloses a device and method for preparing a diamond grinding wheel for polishing the inner wall of an ultra-slender pipe. The device comprises a working platform, a powder feeding cavity, a plasma generator, a grinding wheel base body moving device and a liquid ammonia cooling device. After the diamond abrasive particles and the brazing filler metal are evenly mixed, the diamond abrasive particles and the brazing filler metal are conveyed to the powder feeding cavity through the powder feeding system and sprayed out of a powder outlet of the powder feeding cavity to make contact with a plasma torch ionized by the plasma generator, the brazing filler metal is in a molten state, adheres to the diamond abrasive particles and is sprayed to the grinding wheel base body doing axial feeding motion, and meanwhile the grinding wheel base body does rotating motion. And it is guaranteed that diamond abrasive particles are evenly attached to the surface of the base body, and the brazed grinding wheel base body is cooled through a liquid nitrogen cooling device to complete preparation. According to the device, the diamond grinding wheel is brazed through high-temperature plasma, the holding force of a base body on diamond abrasive particles is high, and the bonding strength is high; the liquid nitrogen cooling device can restrain graphitization of diamond abrasive particles, and it is guaranteed that the abrasive particles have sufficient cutting edges.

Description

Technical Field

[0001] The invention belongs to the field of diamond tools, and in particular relates to the preparation of diamond grinding wheels. Background Art

[0002] Diamond is a common super-hard abrasive with excellent mechanical properties such as high hardness and high strength. Diamond can be used as an abrasive to process at a high cutting rate and precision, and can grind, polish and cut materials with high hardness (such as hard metals, ceramics, glass, stone, etc.). At present, the combination of diamond and metal matrix includes resin bonding, ceramic bonding, electroplating and sintering. All of the above methods are to mechanically embed the diamond on the matrix, with low bonding strength, easy to fall off during processing, and short service life. In addition, the sintering method causes greater thermal damage to the diamond, and the blade height is low, resulting in poor processing effect. Therefore, improving the bonding strength between diamond and matrix and inhibiting the graphitization of diamond are of great significance to the preparation of diamond tools.

[0003] Patent CN105081992B discloses a ceramic resin composite bond diamond grinding wheel and its preparation process. The composite bond diamond grinding wheel can perform high temperature resistant grinding and does not require dressing before grinding. The processed surface quality is excellent, but the diamond is still mechanically embedded in the substrate and the bonding strength is low.

[0004] Patent CN210765558U discloses a vertical electroplated diamond wire saw device, which performs sanding in the vertical direction. The diamonds are evenly distributed and will not be graphitized. However, its essence is still mechanically embedded diamond particles. The coating has a weak holding force on the diamonds, is prone to sanding, and has a short service life.

[0005] Patent CN112720285A discloses a method for manufacturing a diamond grinding tool, which solves the problem of reduced strength of the diamond grinding tool caused by diamond graphitization during sintering in the existing diamond grinding tool manufacturing process. However, the diamond blade height is low and the grinding effect is poor. Summary of the invention

[0006] In order to solve the above-mentioned bonding problem between diamond and substrate and meet the performance requirements of the grinding wheel for polishing the inner wall of ultra-slender tubes, the inventors invented a preparation device and method of a diamond grinding wheel for polishing the inner wall of ultra-slender tubes. The device adopts a plasma torch to braze diamond, and the bonding strength is high. The present invention adopts the following technical solutions:

[0007] 1. A preparation device for a diamond grinding wheel for polishing the inner wall of an ultra-slender pipe, characterized in that it comprises a working platform (1), a powder feeding chamber (2), a plasma generator (3), a grinding wheel base moving device (4), a grinding wheel base (5), and a liquid nitrogen cooling device (6); a circular groove is provided in the middle of the working platform (1) to collect the ejected excess diamond abrasive grains and molten solder; the powder feeding chamber (2) is connected to a powder feeding system (7) and is fixed just above the circular groove of the working platform (1); the plasma generator (3) is connected to a chiller (8) and an air source (9) and is installed on the upper part of the powder feeding chamber (2); the grinding wheel base moving device (4) comprises an axial feeding unit and a rotating unit, the axial feeding unit is fixed on the working platform (1), two rotating units are symmetrically installed on the axial feeding unit, and the grinding wheel base (5) is fastened to the rotating unit; the liquid nitrogen cooling device (6) is fixed on the right side of the working platform (1).

[0008] The powder delivery chamber (2) comprises a chamber (201), a powder delivery port (205), and a connection port (206); the chamber (201) is fixed on the working platform (1), and has a powder chamber (202) and a nozzle (204) inside, and a gap of 1 mm is left at the bottom of the powder chamber (202) as a powder outlet (203); one end of the powder delivery port (205) is welded to the chamber (201) and communicates with the powder chamber (202), and the other end is sealed and connected to a powder delivery system (7), and the powder delivery system (7) comprises a high-pressure argon gas tank (7-1), a powder storage tank (7-2 ) and a powder delivery pump (7-3), all of which are sealed and connected at the interfaces. A pressure control valve is installed on the air flow passage of the high-pressure argon tank (7-1) to adjust the delivery air pressure. Diamond abrasive grains and solder are evenly mixed and loaded into the powder storage tank (7-2) and delivered to the air flow passage inside the pump body by the powder delivery pump (7-3) to form a gas-solid two-phase flow. After passing through the powder delivery port (205), they are dispersed into the powder chamber (202) and ejected from the powder outlet (203); the connecting port (206) is welded above the cavity (201) and is concentric with the nozzle (204), and a thread is provided inside.

[0009] The plasma generator (3) comprises a main body (301), a cooling water inlet (305), an anode (306), a high-frequency power supply (307), a cooling water outlet (308), a center gas inlet (309), a side gas inlet (310) and a cathode (311); a thread is provided at the lower part of the main body (301) and connected to the connecting port (206); a cooling water chamber (302), a plasma generating chamber (303) and an electrode port (304) are provided inside the main body (301); the electrode port (304) is coated with an insulating coating; the anode (306) and the cathode (311) are mounted on the electrode port (304) opposite to each other and The cooling water inlet (305) and the cooling water outlet (308) are welded on the main body (301) at one end to communicate with the cold water chamber (302), and the other end is respectively connected to the water outlet and water inlet of the chiller (8), and the interface is sealed; the central gas inlet (308) and the side gas inlet (309) are welded on the upper part of the main body (301) at one end to communicate with the plasma generating chamber (303), and the other end is respectively connected to the high-pressure argon tank (9-1) and the high-pressure hydrogen tank (9-2) of the gas source (9), and the interface is sealed, and a pressure control valve is installed on the air flow passage to adjust the delivery gas pressure.

[0010] The grinding wheel base motion device (4) comprises an axial feeding unit and a rotating unit; the axial feeding unit comprises a screw motor (401), a screw motor base (402), a coupling (403), a slide base (404), a screw (405), a screw guide rail (406), and slides (407-1, 407-2); the screw motor (401) is fixed to the left side of the working platform (1) through the screw motor base (402); the slide base (404) is mounted on the working platform (1) and is located below the powder blowing chamber (2); two parallel dovetail grooves are provided on the base; the screw (405) is mounted on the slide base (404) and is connected to the screw motor (401) through the coupling (403); the screw guide rail (406) has two screws connected to the screw (405) The two slides (407-1 and 407-2) are placed back to back, and the slides (407-1 and 407-2) are fixed on the screw guide rail (406) and connected to the dovetail groove of the slide base (404); two rotating units are symmetrically installed on the slides (407-1 and 407-2), and the rotating units include a tube rotating motor (408), a motor base (409), a precision chuck (410), and a motor baffle (411); the tube rotating motor (408) is fixed on the slide (407) through the motor base (409), the precision chuck (410) is fastened to the rotating shaft of the tube rotating motor (408), and the motor baffle (411) is adhered to the upper part of the motor base (409) to block the excess molten brazing material ejected; the grinding wheel base (5) is clamped by the precision chuck (410), and the base axis and the center of the nozzle (204) are in the same vertical plane.

[0011] The liquid nitrogen cooling device (6) comprises a self-pressurizing liquid nitrogen tank (601) and an ejector (606); the self-pressurizing liquid nitrogen tank (601) is placed on a working platform (1), and is provided with a safety valve (602), a liquid level gauge (603) and a liquid nitrogen outlet (604); the safety valve (602) is provided with a pressure gauge; the ejector (606) is fixed on the right side of the working platform (1), and the center of the ejector port (607) is located at the same horizontal plane as the axis of the grinding wheel base (5); a throttle valve (605) is installed on the liquid nitrogen passage to adjust the liquid nitrogen flow rate; when the grinding wheel base (5) is fed into the working range of the ejector (606), the valve of the liquid nitrogen outlet (604) is opened, and the liquid nitrogen is ejected onto the grinding wheel base (5), thereby inhibiting the graphitization of the diamond abrasive grains and accelerating the solidification of the molten solder.

[0012] 2. The device for preparing a diamond grinding wheel for polishing the inner wall of an ultra-slender tube according to claim 1, characterized in that the inner wall of the nozzle (204) and the plasma generating chamber (303) are both coated with a high temperature resistant coating.

[0013] 3. The preparation device of a diamond grinding wheel for polishing the inner wall of an ultra-slender pipe according to claim 1 is characterized in that: the average particle size of the diamond abrasive grains is 180um; the brazing material is Ag-Cu-Ti brazing powder with an average particle size of 50um.

[0014] 4. A preparation device for a diamond grinding wheel for polishing the inner wall of an ultra-slender pipe according to claim 1, characterized in that: the grinding wheel substrate (5) is a 304 stainless steel hard wire straight bar with a diameter of 1 mm and a length of 400 mm, and micro holes and micro grooves are machined at both ends by electric spark processing. Before brazing, the surface of the grinding wheel substrate (5) needs to be cleaned and roughened to remove grease and oxides on the surface, promote the adhesion and extension of the molten solder on the substrate surface, and improve the bonding strength between the molten solder and the substrate.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The bonding strength between diamond and substrate is high.

[0017] 2. The liquid nitrogen cooling device can not only accelerate the solidification of molten brazing material and improve processing efficiency, but also inhibit the graphitization of diamond abrasives to ensure that the diamond grinding wheel has sufficient cutting edge.

[0018] 3. Diamond abrasive grains can be evenly distributed without pre-arrangement on the surface of the grinding wheel substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the device, wherein: 1-working platform, 2-powder feeding chamber, 3-plasma torch generator, 4-grinding wheel base movement device, 5-grinding wheel base, 6-liquid nitrogen cooling device.

[0020] Figure 2 It is a front cross-sectional view of the powder delivery chamber, wherein: 201-chamber, 202-powder chamber, 203-powder outlet, 204-nozzle, 205-powder delivery port, 206-connection port.

[0021] Figure 3 It is a front cross-sectional view of a plasma generator, wherein: 301-main body, 302-cold water chamber, 303-plasma generating chamber, 304-electrode port, 305-cooling water inlet, 306-anode, 307-high frequency power supply, 308-cooling water outlet, 309-center gas inlet, 310-side gas inlet, 311-cathode.

[0022] Figure 4 It is a structural schematic diagram of the grinding wheel base motion device, wherein: 401-screw motor, 402-screw motor base, 403-coupling, 404-slide base, 405-screw, 406-screw guide, 407-slide, 408-tube rotary motor, 409-motor base, 410-precision chuck, 411-motor baffle.

[0023] Figure 5 It is a structural schematic diagram of a liquid nitrogen cooling device, wherein: 601-self-pressurized liquid nitrogen tank, 602-safety valve, 603-liquid level gauge, 604-liquid nitrogen outlet, 605-throttle valve, 606-injector, 607-injection port.

[0024] Figure 6 This is the structural diagram of the grinding wheel base. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, the overall structure of the present invention comprises a working platform (1), a powder feeding chamber (2), a plasma generator (3), a grinding wheel base moving device (4), a grinding wheel base (5), and a liquid nitrogen cooling device (6); a circular groove is provided in the middle of the working platform (1) to collect the ejected excess diamond abrasive grains and molten solder; the powder feeding chamber (2) is connected to a powder feeding system (7) and is fixed just above the circular groove of the working platform (1); the plasma generator (3) is connected to a chiller (8) and an air source (9) and is installed on the upper part of the powder feeding chamber (2); the grinding wheel base moving device (4) comprises an axial feeding unit and a rotating unit, the axial feeding unit is fixed on the working platform (1), two rotating units are symmetrically installed on the axial feeding unit, and the grinding wheel base (5) is fastened to the rotating unit; the liquid nitrogen cooling device (6) is fixed on the right side of the working platform (1).

[0027] like Figure 2As shown, the powder delivery chamber comprises a chamber (201), a powder delivery port (205), and a connection port (206); the chamber (201) is fixed on the working platform (1), and has a powder chamber (202) and a nozzle (204) inside, and a gap of 1 mm is left at the bottom of the powder chamber (202) as a powder outlet (203); one end of the powder delivery port (205) is welded to the chamber (201) and connected to the powder chamber (202), and the other end is sealed and connected to the powder delivery system (7), and the powder delivery system (7) comprises a high-pressure argon gas tank (7-1), a powder storage tank (7-2) The three parts are sealed and connected at the interfaces. A pressure control valve is installed on the air flow passage of the high-pressure argon tank (7-1) to adjust the delivery air pressure. Diamond abrasive grains and solder are evenly mixed and loaded into the powder storage tank (7-2) and sent to the air flow passage inside the pump body by the powder feeding pump (7-3) to form a gas-solid two-phase flow. After passing through the powder feeding port (205), they are dispersed into the powder chamber (202) and ejected from the powder outlet (203); the connecting port (206) is welded above the cavity (201) and is concentric with the nozzle (204), and a thread is provided inside.

[0028] like Figure 3 As shown, the plasma generator (3) includes a main body (301), a cooling water inlet (305), an anode (306), a high-frequency power supply (307), a cooling water outlet (308), a center gas inlet (309), a side gas inlet (310) and a cathode (311); a thread is provided at the lower part of the main body (301) and connected to the connecting port (206); a cooling water chamber (302), a plasma generating chamber (303) and an electrode port (304) are provided inside the main body (301); the electrode port (304) is coated with an insulating coating; the anode (306) and the cathode (311) are mounted on the electrode port (304) opposite to each other and The cooling water inlet (305) and the cooling water outlet (308) are welded on the main body (301) at one end to communicate with the cold water chamber (302), and the other end is respectively connected to the water outlet and water inlet of the chiller (8), and the interface is sealed; the central gas inlet (308) and the side gas inlet (309) are welded on the upper part of the main body (301) at one end to communicate with the plasma generating chamber (303), and the other end is respectively connected to the high-pressure argon tank (9-1) and the high-pressure hydrogen tank (9-2) of the gas source (9), and the interface is sealed, and a pressure control valve is installed on the air flow passage to adjust the delivery gas pressure.

[0029] like Figure 4As shown, the grinding wheel base motion device (4) includes an axial feed unit and a rotation unit; the axial feed unit includes a screw motor (401), a screw motor base (402), a coupling (403), a slide base (404), a screw (405), a screw guide rail (406), and slides (407-1, 407-2), the screw motor (401) is fixed to the left side of the working platform (1) through the screw motor base (402), the slide base (404) is installed on the working platform (1), located below the powder blowing chamber (2), and two parallel dovetail grooves are opened on the base, the screw (405) is installed on the slide base (404) and connected to the screw motor (401) through the coupling (403), and the screw guide rail (406) has two screws connected to the screw (405). The two slides (407-1 and 407-2) are placed back to back, and the slides (407-1 and 407-2) are fixed on the screw guide rail (406) and connected to the dovetail groove of the slide base (404); two rotating units are symmetrically installed on the slides (407-1 and 407-2), and the rotating units include a tube rotating motor (408), a motor base (409), a precision chuck (410), and a motor baffle (411); the tube rotating motor (408) is fixed on the slide (407) through the motor base (409), the precision chuck (410) is fastened to the rotating shaft of the tube rotating motor (408), and the motor baffle (411) is adhered to the upper part of the motor base (409) to block the excess molten brazing material ejected; the grinding wheel base (5) is clamped by the precision chuck (410), and the base axis and the center of the nozzle (204) are in the same vertical plane.

[0030] like Figure 5 As shown, the cooling device (6) comprises a self-pressurizing liquid nitrogen tank (601) and an ejector (606); the self-pressurizing liquid nitrogen tank (601) is placed on the working platform (1), and is provided with a safety valve (602), a liquid level gauge (603) and a liquid nitrogen outlet (604), and the safety valve (602) is provided with a pressure gauge; the ejector (606) is fixed on the right side of the working platform (1), and the center of the ejector port (607) is located at the same horizontal plane as the axis of the grinding wheel base (5); a throttle valve (605) is installed on the liquid nitrogen passage to adjust the liquid nitrogen flow rate; when the grinding wheel base (5) is fed into the working range of the ejector (606), the valve of the liquid nitrogen outlet (604) is opened, and the liquid nitrogen is ejected onto the grinding wheel base (5), thereby inhibiting the graphitization of the diamond abrasive grains and accelerating the solidification of the molten solder.

[0031] like Figure 6 As shown, the grinding wheel base (5) has micro grooves and holes machined by electrical sparks at both ends.

[0032] A method for preparing a diamond grinding wheel for polishing the inner wall of an ultra-slender tube comprises the following steps:

[0033] Step 1: First, pre-treat the grinding wheel base (5) and fix the grinding wheel base (5) on the precision chuck (410).

[0034] Step 2: Start the water chiller to fill the water chiller (302), start the high-frequency power supply (306) to generate an arc path between the anode (305) and the cathode (310), open the gas source (9), and adjust the delivery pressures of argon and hydrogen to 0.7 MPa and 0.4 MPa respectively. Argon and hydrogen enter the plasma generating chamber (303) and are ionized into free high-temperature plasma when passing through the arc path between the positive and negative electrodes, and are ejected from the lower end of the plasma generating chamber (303) to form a plasma torch.

[0035] Step 3: diamond abrasive grains and solder are uniformly mixed in a volume ratio of 4:1 and loaded into a powder storage tank (7-2). The powder feeding system (7) is started to feed the mixed powder of diamond abrasive grains and solder into the powder chamber (202) at a powder feeding rate of 100 g / min and break it up. The mixed powder is then ejected from the powder outlet (203) to contact the plasma torch. The solder that contacts the plasma torch becomes molten and adheres to the diamond abrasive grains and is ejected from the nozzle (204) under the push of the plasma torch.

[0036] Step 4: Start the grinding wheel base moving device (4), and the grinding wheel base (5) performs rotational motion while being axially fed. When the grinding wheel base (5) is fed to the working area of ​​the powder feeding chamber (2), the diamond abrasive grains adhering to the molten solder are sprayed onto the surface of the grinding wheel base (5) and adhere to the surface.

[0037] Step 5: The grinding wheel base (5) continues to be axially fed. When the base area that has been brazed is fed to the working range of the cooler (606), the liquid nitrogen outlet (605) is opened, and the throttle valve (606) is adjusted to allow the liquid nitrogen to be sprayed onto the grinding wheel base (5) through the injection port (607) at a flow rate of 0.3 m / s, thereby inhibiting the graphitization of the diamond in the brazed area and accelerating the solidification of the molten brazing material. As the grinding wheel base (5) continues to move, the diamond abrasive grains are evenly solidified on the surface of the entire grinding wheel base (5).

[0038] Step 6. Finally, turn off the equipment and remove the diamond grinding wheel to complete the preparation.

[0039] It should be further explained in the description of the present invention that the directions or positional relationships indicated by terms such as "front", "rear", "left", "right", "up", "down", "middle", "horizontal" and "vertical" are based on the positional relationships shown in the drawings and are only for the convenience of description, and do not indicate or imply that the original component or device referred to must have a specific direction, be constructed or operate in a specific direction.

[0040] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "install", "fasten", "fix" and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to the specific circumstances.

Claims

1. A preparation device for a diamond grinding wheel for polishing the inner wall of an ultra-slender tube, characterized in that: The invention comprises a working platform (1), a powder feeding chamber (2), a plasma generator (3), a grinding wheel base moving device (4), a grinding wheel base (5), and a liquid nitrogen cooling device (6); a circular groove is provided in the middle of the working platform (1) to collect the ejected excess diamond abrasive grains and molten solder; the powder feeding chamber (2) is connected to a powder feeding system (7) and is fixed just above the circular groove of the working platform (1); the plasma generator (3) is connected to a chiller (8) and an air source (9) and is installed on the upper part of the powder feeding chamber (2); the grinding wheel base moving device (4) comprises an axial feeding unit and a rotating unit, the axial feeding unit is fixed on the working platform (1), two rotating units are symmetrically installed on the axial feeding unit, and the grinding wheel base (5) is fastened to the rotating unit; the liquid nitrogen cooling device (6) is fixed on the right side of the working platform (1); The powder delivery chamber (2) comprises a chamber (201), a powder delivery port (205), and a connection port (206); the chamber (201) is fixed on the working platform (1), and has a powder chamber (202) and a nozzle (204) inside, and a gap of 1 mm is left at the bottom of the powder chamber (202) as a powder outlet (203); one end of the powder delivery port (205) is welded to the chamber (201) and communicates with the powder chamber (202), and the other end is sealed and connected to a powder delivery system (7), and the powder delivery system (7) comprises a high-pressure argon gas tank (7-1), a powder storage tank (7-2 ) and a powder delivery pump (7-3), all of which are sealed at the interfaces. A pressure control valve is installed on the air flow passage of the high-pressure argon tank (7-1) to adjust the delivery air pressure. Diamond abrasive grains and solder are evenly mixed and loaded into the powder storage tank (7-2) and delivered to the air flow passage inside the pump body by the powder delivery pump (7-3) to form a gas-solid two-phase flow. After passing through the powder delivery port (205), they are dispersed into the powder chamber (202) and ejected from the powder outlet (203); the connecting port (206) is welded on the top of the cavity (201) and is concentric with the nozzle (204), and a thread is provided inside it; The plasma generator (3) comprises a main body (301), a cooling water inlet (305), an anode (306), a high-frequency power supply (307), a cooling water outlet (308), a center gas inlet (309), a side gas inlet (310) and a cathode (311); a thread is provided at the lower part of the main body (301) and connected to the connecting port (206); a cooling water chamber (302), a plasma generating chamber (303) and an electrode port (304) are provided inside the main body (301); the electrode port (304) is coated with an insulating coating; the anode (306) and the cathode (311) are mounted on the electrode port (304) opposite to each other and connected to a high-frequency power source (307); one end of a cooling water inlet (305) and a cooling water outlet (308) are welded to the main body (301) to communicate with the cold water chamber (302), and the other end is respectively connected to the water outlet and water inlet of the chiller (8), and the interface is sealed; one end of a central gas inlet (308) and a side gas inlet (309) are welded to the upper part of the main body (301) to communicate with the plasma generating chamber (303), and the other end is respectively connected to the high-pressure argon tank (9-1) and the high-pressure hydrogen tank (9-2) of the gas source (9), and the interface is sealed; a pressure control valve is installed on the air flow passage to adjust the delivery gas pressure; The grinding wheel base motion device (4) comprises an axial feeding unit and a rotating unit; the axial feeding unit comprises a screw motor (401), a screw motor base (402), a coupling (403), a slide base (404), a screw (405), a screw guide rail (406), and slides (407-1, 407-2); the screw motor (401) is fixed to the left side of the working platform (1) through the screw motor base (402); the slide base (404) is mounted on the working platform (1) and is located below the powder blowing chamber (2); two parallel dovetail grooves are provided on the base; the screw (405) is mounted on the slide base (404) and is connected to the screw motor (401) through the coupling (403); the screw guide rail (406) has two screws connected to the screw (405) The two slides (407-1 and 407-2) are placed back to back, and the slides (407-1 and 407-2) are fixed on the screw guide rail (406) and connected to the dovetail groove of the slide base (404); two rotating units are symmetrically installed on the slides (407-1 and 407-2), and the rotating units include a tube rotating motor (408), a motor base (409), a precision chuck (410), and a motor baffle (411); the tube rotating motor (408) is fixed on the slide (407) through the motor base (409), the precision chuck (410) is fastened to the rotating shaft of the tube rotating motor (408), and the motor baffle (411) is adhered to the upper part of the motor base (409) to block the excess molten solder ejected; the grinding wheel base (5) is clamped by the precision chuck (410), and the base axis and the center of the nozzle (204) are in the same vertical plane; The liquid nitrogen cooling device (6) comprises a self-pressurizing liquid nitrogen tank (601) and an ejector (606); the self-pressurizing liquid nitrogen tank (601) is placed on a working platform (1), and is provided with a safety valve (602), a liquid level gauge (603) and a liquid nitrogen outlet (604); the safety valve (602) is provided with a pressure gauge; the ejector (606) is fixed on the right side of the working platform (1), and the center of the ejector port (607) is located at the same horizontal plane as the axis of the grinding wheel base (5); a throttle valve (605) is installed on the liquid nitrogen passage to adjust the liquid nitrogen flow rate; when the grinding wheel base (5) is fed into the working range of the ejector (606), the valve of the liquid nitrogen outlet (604) is opened, and the liquid nitrogen is ejected onto the grinding wheel base (5), thereby inhibiting the graphitization of the diamond abrasive grains and accelerating the solidification of the molten solder.

2. Pre-treat the grinding wheel base (5) and then fix the grinding wheel base (5) on the precision chuck (410), start the water chiller to fill the cooling water chamber (302), start the high-frequency power supply (306) to generate an arc path between the anode (305) and the cathode (310), open the gas source (9) to allow argon and hydrogen to enter the plasma generating chamber (303) and be ionized into free high-temperature plasma when passing through the arc path between the positive and negative electrodes and ejected from the lower end of the plasma generating chamber (303) to form a plasma torch, mix the diamond abrasive grains and the brazing material evenly and load them into the powder storage tank (7-2), start the powder feeding system (7) to feed the mixed powder of the diamond abrasive grains and the brazing material to the powder chamber (202), and eject the mixed powder from the powder outlet (203) to contact the plasma torch after being dispersed. The mixed powder contacts the brazing material of the plasma torch. The material is in a molten state and adheres to the diamond abrasive grains and is ejected from the nozzle (204) under the push of the plasma torch. The grinding wheel base moving device (4) is started. The grinding wheel base (5) is fed axially and rotates itself. When it is fed to the working area of ​​the powder feeding chamber (2), the diamond abrasive grains adhered to the molten brazing material are sprayed to the surface of the grinding wheel base (5) and adhere to the surface. The grinding wheel base (5) continues to be fed axially. When the base area where brazing has been completed is fed to the working range of the cooler (606), the liquid nitrogen outlet (605) is opened, and the throttle valve (606) is adjusted to allow the liquid nitrogen to be sprayed onto the grinding wheel base (5) through the injection port (607), thereby inhibiting the graphitization of diamond and accelerating the solidification of the molten brazing material. As the grinding wheel base (5) continues to move, the diamond abrasive grains are evenly solidified on the surface of the entire grinding wheel base (5).

3. The manufacturing device of a diamond grinding wheel for polishing the inner wall of an ultra-slender tube according to claim 1, characterized in that: The nozzle (204) and the inner wall of the plasma generating chamber (303) are both coated with a high temperature resistant coating.

4. The device for preparing a diamond grinding wheel for polishing the inner wall of an ultra-slender tube according to claim 1, characterized in that: The average particle size of the diamond abrasive grains is 180 um; the brazing material is Ag-Cu-Ti brazing powder with an average particle size of 50 um.

5. The device for preparing a diamond grinding wheel for polishing the inner wall of an ultra-slender tube according to claim 1, characterized in that: The grinding wheel base (5) is a 304 stainless steel hard wire straight bar with a diameter of 1 mm and a length of 400 mm. Micro holes and micro grooves are machined at both ends by electric spark processing. Before brazing, the surface of the grinding wheel base (5) needs to be cleaned and roughened to remove grease and oxides on the surface, promote the adhesion and extension of molten brazing material on the base surface, and improve the bonding strength between the molten brazing material and the base.

6. A method for preparing a diamond grinding wheel for polishing the inner wall of an ultra-slender tube, characterized in that: The method of preparing a diamond grinding wheel using the device according to claim 1 comprises the following steps: Step 1: pre-treat the grinding wheel base (5), and then fix the grinding wheel base (5) on the precision chuck (410); Step 2: Start the water chiller to fill the water chiller (302), start the high-frequency power supply (306) to generate an arc path between the anode (305) and the cathode (310), open the gas source (9), adjust the delivery pressures of argon and hydrogen to 0.7 MPa and 0.4 MPa respectively, and the argon and hydrogen enter the plasma generating chamber (303) and are ionized into free high-temperature plasma when passing through the arc path between the positive and negative electrodes, and are ejected from the lower end of the plasma generating chamber (303) to form a plasma torch; Step 3, diamond abrasive grains and solder are uniformly mixed in a volume ratio of 4:1 and loaded into a powder storage tank (7-2), a powder feeding system (7) is started to feed the mixed powder of diamond abrasive grains and solder into a powder chamber (202) at a powder feeding rate of 100 g / min, and the mixed powder is sprayed out from a powder outlet (203) to contact with a plasma torch, and the solder contacting the plasma torch is molten and adheres to the diamond abrasive grains and is sprayed out from a nozzle (204) under the push of the plasma torch; Step 4: Start the grinding wheel base moving device (4), and the grinding wheel base (5) performs rotational motion while being axially fed. When the grinding wheel base (5) is fed to the working area of ​​the powder feeding chamber (2), the diamond abrasive grains adhering to the molten solder are sprayed onto the surface of the grinding wheel base (5) and adhere to the surface; Step 5: The grinding wheel base (5) continues to be axially fed. When the base area that has been brazed is fed to the working range of the cooler (606), the liquid nitrogen outlet (605) is opened, and the throttle valve (606) is adjusted to allow the liquid nitrogen to be sprayed onto the grinding wheel base (5) through the injection port (607) at a flow rate of 0.3 m / s to inhibit the graphitization of diamond and accelerate the solidification of the molten brazing material. As the grinding wheel base (5) continues to move, the diamond abrasive grains are evenly solidified on the surface of the entire grinding wheel base (5); Step 6. Finally, turn off the equipment and remove the diamond grinding wheel to complete the preparation.

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