Combined machining method and system for high-precision multi-channel main shaft of semiconductor CMP equipment

Abstract

The invention belongs to the field of machining, and particularly relates to a combined machining method and system for a high-precision multi-channel main shaft of semiconductor CMP equipment, and the machining method comprises the following steps: clamping a workpiece on a workbench; calibrating the precision of each shaft of the workbench; measuring the length and the diameter of the inner-cooling drill bit by using a tool setting gauge, and establishing tool compensation parameters; an inner-cooling drill bit is installed on the cutter shaft, and the workpiece is moved to make the axis of the inner-cooling drill bit coincide with the axis of the target channel hole; the cooling unit is connected with the inner-cooling drill bit, and the output pressure of cooling liquid in the cooling unit is adjusted to be larger than 60 MPA; after the temperature of the cooling liquid is controlled to be stabilized at 25-30 DEG C, machining is Triggering a monitoring compensation device of the workpiece to detect and trim machining coordinates every time a group of channel holes are finished; by means of the method, high-precision machining of the 12-channel main shaft can be achieved, and independent production of key parts in CMP equipment is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of machining, and particularly relates to a composite machining method and system for a high-precision multi-channel spindle of a semiconductor CMP device. Background Art

[0002] In the field of semiconductor manufacturing, as a core precision component of a CMP device, the performance of a 12-channel spindle directly determines the success or failure of the polishing process. The "12-channel" structural design of the 12-channel spindle integrates multiple functional channels such as gas paths, liquid paths, and circuits. By precisely controlling the pressure, flow rate, and signal transmission of each channel, precise adjustment of key parameters such as wafer rotation, polishing liquid supply, and temperature control is achieved. Therefore, the precision of the "12" channels is crucial for the polishing process.

[0003] However, the high-precision machining technology of 12-channel spindles has long been monopolized by American enterprises. This technology monopoly not only leads to the long-term dependence on imports of the core components of our country's CMP devices, pushing up the production costs of semiconductor manufacturing enterprises, but also severely restricts the independent and controllable development process of our country's semiconductor industry. Once encountering changes in the international situation or trade sanctions, the domestic semiconductor industry chain will face the risk of rupture. Therefore, it is extremely urgent to break through the high-precision machining technology of 12-channel spindles. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a composite machining method and system for a high-precision multi-channel spindle of a semiconductor CMP device, which can achieve high-precision machining of a 12-channel spindle and realize the autonomous production of key components in the CMP device.

[0005] The specific technical solution adopted by the present invention is as follows:

[0006] A composite machining method for a high-precision multi-channel spindle of a semiconductor CMP device, comprising the following steps:

[0007] S1. Clamp the workpiece on the workbench;

[0008] S2. Calibrate the accuracy of each axis of the workbench;

[0009] S3. Use a tool setter to measure the length and diameter of the internal coolant drill bit and establish tool compensation parameters;

[0010] S4. Install the internal coolant drill bit on the tool axis and move the workpiece to make the axis of the internal coolant drill bit coincide with the axis of the channel hole to be machined;

[0011] S5. Connect the cooling unit to the internal coolant drill bit and adjust the coolant output pressure in the cooling unit > 60 MPA;

[0012] S6. Control the coolant temperature to stabilize at 25-30°C before starting to process the channel hole;

[0013] S7, grouping the channel holes on the workpiece, triggering the monitoring compensation device to detect and adjust the processing coordinates after processing each group of channel holes, and processing the next group of channel holes after adjusting the processing coordinates, until the processing of each group of channel holes is completed.

[0014] The system includes a tool shaft, a cooling unit and a monitoring and compensation device which are respectively connected to the controller signal. The workpiece is clamped on the workbench by means of an angle fixture. The axial direction of the workpiece and the axial direction of the tool shaft are set at an angle α, and the axial direction of the channel hole and the axial direction of the workpiece are set at an angle β, and the angle α=angle β. The workpiece has the freedom to move along the X-axis, Y-axis and Z-axis by means of the workbench. The internal cooling drill is drive-connected to the tool shaft and has the freedom to reciprocate toward the workpiece.

[0015] The angle tooling includes a mounting plate, a motor rotor, a motor stator and a clamp. The motor rotor and the motor stator are matched with each other, the motor stator is fixedly connected to the mounting plate, the clamp is fixedly connected to the motor rotor, the workpiece is clamped on the workbench with the help of the clamp and has the freedom of rotation with the help of the cooperation between the motor rotor and the motor stator.

[0016] The cooling unit includes a liquid storage tank for supplying liquid to the internal cooling drill bit, the motor rotor is a hollow tubular structure, and a cooling sleeve is arranged on the mounting plate. The cooling sleeve passes through the inner cavity of the motor rotor and is arranged in contact with the workpiece and is arranged corresponding to the channel hole to be processed. The cooling sleeve includes an outer wall and an inner wall, and a water inlet cavity is formed between the outer wall and the inner wall. The two ends of the inner wall are in contact with the workpiece, and a drainage cavity is formed between the inner wall and the workpiece. The output end of the water inlet cavity is connected to the input end of the drainage cavity and is arranged close to the fixture. The input end of the water inlet cavity and the output end of the drainage cavity are respectively arranged close to the mounting plate and are respectively connected to the liquid storage tank by means of a water inlet pipe and a drainage pipe to form a circulation path for the coolant.

[0017] The drainage pipe is provided with a negative pressure water pump, and the negative pressure water pump is connected with the controller signal.

[0018] The monitoring and compensation device is a Renishaw online monitoring and compensation device.

[0019] The cooling unit also includes a liquid supply pipe and a thermostat. The liquid storage tank supplies liquid to the internally cooled drill bit via the liquid supply pipe. A high-pressure water pump is provided on the liquid supply pipe. The liquid inlet end of the liquid supply pipe is connected to the liquid storage tank. The liquid outlet end of the liquid supply pipe is connected to the tool shaft via a high-pressure rotary joint. The thermostat is connected to the liquid storage tank and regulates the temperature of the coolant in the liquid storage tank. The high-pressure water pump and thermostat are respectively connected to the controller signal.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention uses an internally cooled drill bit to machine the through holes of the workpiece. The high-pressure coolant is directly delivered to the cutting area through the internal channel of the internally cooled drill bit. The coolant can quickly and accurately carry away the cutting heat, effectively reduce the cutting temperature, and inhibit the dimensional error and shape error caused by thermal deformation of the workpiece, effectively solving the problems of controlling the straightness of deep holes and the roughness of the hole wall, and providing a reliable guarantee for the high-precision machining of the through holes on the workpiece.

[0022] The high-pressure coolant supplied to the internally cooled drill bit has a strong scouring force, which can quickly discharge the chips generated during the cutting process from the through hole, avoiding problems such as secondary cutting caused by chip residue and scratching the surface of the workpiece, and further improving the machining accuracy of the through hole.

[0023] With the help of a thermostat, the temperature of the coolant in the liquid storage tank is controlled at 25 - 30 °C, so that the coolant maintains good performance, such as fluidity and viscosity, which can enable the coolant to play the roles of cooling, lubricating, and chip removal with stable performance, maintain the stability of the cutting process, and further reduce the machining error and improve the machining accuracy and reliability of 12 through holes.

[0024] An online monitoring and compensation device is used to online monitor the machining error during the machining process and perform compensation and correction in a timely manner to prevent the accumulation of machining errors, and further improve the overall machining accuracy and consistency of the workpiece.

[0025] An angle tooling is used to clamp the workpiece and keep it at a fixed inclination angle on the workbench and can rotate around the axis of the workpiece itself. Through the rotation of the workpiece, the axes of the to-be-machined through holes are collinear with the axis of the internally cooled drill bit, and the machining of multiple channels on the workpiece can be achieved with only one adjustment of the position of the internally cooled drill bit.

[0026] The corresponding angle tooling is selected according to the through holes with different inclination angles to achieve the quick clamping of workpieces of different models.

[0027] With the help of the angle tooling, the holes that originally needed to be machined obliquely are transformed into conventional drilling parallel to the tool axis. There is no need to use a complex angle head or a universal tooling to drive the internally cooled drill bit to be inclined, avoiding the problem of large machining errors caused by the multiple changes of the position and angle of the internally cooled drill bit, reducing the machining difficulty, and effectively improving the machining accuracy of the through hole.

[0028] A cooling sleeve that fits the workpiece is provided on the mounting plate. The coolant enters the cooling sleeve to further cool the machining area of the workpiece, preventing the temperature of the shaft rod from rising rapidly due to the thin wall during the machining of the through hole, avoiding thermal deformation of the shaft rod, and further improving the drilling accuracy. Description of the Drawings

[0029] Figure 1 It is a block diagram of the processing system of the present invention;

[0030] Figure 2 It is a structural schematic diagram of the processing system;

[0031] Figure 3 It is Figure 2 an enlarged view of the partial A in

[0032] Figure 4 It is an assembly schematic diagram of the workpiece and the cooling sleeve during the processing;

[0033] Figure 5 It is a structural schematic diagram of the workpiece after the channel hole is processed;

[0034] In the drawings, 1 is the workpiece, 101 is the shaft rod, 2 is the internal cooling drill bit, 3 is the tool shaft, 4 is the channel hole, 5 is the monitoring and compensation device, 6 is the controller, 7 is the workbench, 8 is the angle tooling, 801 is the mounting plate, 8011 is the mounting surface, 802 is the motor rotor, 803 is the motor stator, 804 is the fixture, 9 is the cooling sleeve, 901 is the outer side wall, 902 is the inner side wall, 903 is the water inlet cavity, 904 is the water drainage cavity, 10 is the negative pressure water pump, 11 is the high pressure water pump, and 12 is the thermostat. Specific Embodiments

[0035] The present invention will be further described below in conjunction with the drawings and specific embodiments:

[0036] In a specific embodiment, the present invention relates to a composite processing method for a high-precision multi-channel spindle of a semiconductor CMP device, including the following steps:

[0037] S1. Clamp the workpiece 1 on the workbench 7;

[0038] S2. Calibrate the accuracy of each axis of the workbench 7;

[0039] S3. Use a tool setter to measure the length and diameter of the internal cooling drill bit 2 and establish tool compensation parameters;

[0040] S4. Install the internal cooling drill bit 2 on the tool shaft 3 and move the workpiece 1 to make the axis of the internal cooling drill bit 2 coincide with the axis of the channel hole 4 to be processed;

[0041] S5. Connect the cooling unit to the internal cooling drill bit 2 and adjust the coolant output pressure in the cooling unit > 60 MPA;

[0042] S6. Control the coolant temperature to be stable at 25 - 30 °C and then start processing the channel hole 4;

[0043] S7, the channel holes 4 on the workpiece 1 are grouped, and after each group of channel holes 4 is processed, the monitoring compensation device 5 is triggered to detect and adjust the processing coordinates, and the next group of channel holes 4 is processed after the processing coordinates are adjusted, until the processing of each group of channel holes 4 is completed, and the workpiece 1 obtained by processing is as follows Figure 5 shown.

[0044] The processing method processes the channel hole 4 with an internally cooled drill 2 and controls the output pressure of the coolant in the cooling unit. During the processing, the internally cooled drill 2 directly delivers high-pressure coolant to the cutting area through the internal channel. Compared with the traditional external cooling method, the coolant can quickly and accurately take away the cutting heat, effectively reduce the cutting temperature, and suppress the dimensional error and shape error of the workpiece 1 caused by thermal deformation, providing reliable guarantee for the processing of the channel hole 4 on the workpiece 1. On the other hand, the high-pressure coolant sprayed by the internally cooled drill 2 has a strong flushing force, which can quickly discharge the chips generated during the cutting process from the channel hole 4, avoiding problems such as secondary cutting and scratching the workpiece surface caused by chip residue, and further improving the processing accuracy of the channel hole 4.

[0045] Controlling the temperature of the coolant at 25-30°C can ensure the stable performance of the coolant, give full play to the cooling, lubrication and chip removal functions, maintain the stability of the cutting process, make the processing quality of each channel hole 4 consistent, and thus ensure the stable performance of the semiconductor CMP equipment.

[0046] During the machining process, the monitoring and compensation device 5 is used to monitor the machining errors online and make compensation corrections in time to ensure that the 12 channel holes 4 can meet the high-precision requirements, effectively improving the overall machining accuracy and consistency of the multi-channel spindle.

[0047] A processing system is used to implement the composite processing method of the high-precision multi-channel spindle of the semiconductor CMP equipment. The processing system is a four-axis linkage processing center, such as Figures 1-2As shown in the figure, the four-axis linkage machining center includes a workbench 7, a tool axis 3, a cooling unit, and a monitoring and compensation device 5 that are respectively connected to the controller 6 by signals. The workpiece 1 is clamped on the workbench 7 with the aid of an angle tooling 8. The axial direction of the workpiece 1 and the axial direction of the tool axis 3 are set at an angle α, and the axial direction of the through-hole 4 and the axial direction of the workpiece 1 are set at an angle β, and the angle α = the angle β. The workpiece 1 is inclined and clamped on the machine tool with the aid of the angle tooling 8, so that the axial direction of the to-be-machined through-hole 4 is collinear with the axial direction of the tool axis 3. The through-holes 4 are arranged in a circumferential array around the axial direction of the workpiece 1. Therefore, after machining one through-hole 4 is completed, the internal cooling drill bit 2 retracts, and the workpiece 1 rotates around its own axis, and the next to-be-machined through-hole 4 can be collinear with the axial direction of the internal cooling drill bit 2. With the aid of the angle tooling 8, the holes that originally needed to be inclinedly machined are transformed into conventional drilling parallel to the tool axis, without the need to use a complex angle head or a universal tooling to drive the internal cooling drill bit 2 to be inclined, avoiding the problem of large machining errors caused by the internal cooling drill bit 2 changing positions and angles multiple times, reducing the machining difficulty, and effectively improving the machining accuracy of the through-hole 4. On the other hand, after the internal cooling drill bit 2 retracts, only the workpiece 1 needs to be rotated, without the need for the tool axis or the workbench 7 to move significantly, greatly shortening the non-cutting time, and thus greatly improving the machining efficiency.

[0048] The workbench 7 is a three-axis workbench. The workpiece 1 has degrees of freedom of moving along the X-axis, Y-axis, and Z-axis with the aid of the workbench 7. The internal cooling drill bit 2 is drivingly connected to the tool axis 3 and has a degree of freedom of reciprocating movement towards the workpiece 1.

[0049] The setting of the angle tooling 8 in combination with the cooling unit and the monitoring and compensation device 5 can realize the automated and precise machining of the through-holes 4 on the workpiece 1, greatly improving the machining accuracy and machining efficiency.

[0050] The angle tooling 8 includes a mounting plate 801, a motor rotor 802, a motor stator 803, and a fixture 804. The motor rotor 802 is set in a supporting manner with the motor stator 803. The motor stator 803 is fixedly connected to the mounting plate 801. The fixture 804 is fixedly connected to the motor rotor 802. The workpiece 1 is clamped on the workbench 7 with the aid of the fixture 804 and has a degree of freedom of rotation with the aid of the cooperation between the motor rotor 802 and the motor stator 803. The controller drives the coil on the motor stator 803 to be energized by sending a signal, thereby driving the motor rotor 802 to carry the workpiece 1 to rotate. The workpiece 1, the fixture, and the motor rotor 802 are coaxially arranged to realize the rotation of the workpiece 1 around its own axis. In this embodiment, there are 12 through-holes 4 on the workpiece 1. Therefore, after the internal cooling drill bit 2 retracts, the workpiece 1 rotates 30°, and the internal cooling drill bit 2 advances to machine the next through-hole 4.

[0051] In this embodiment, the angle β is 1.1°, then the included angle between the mounting surface 8011 of the mounting plate 801 and the axis of the tool axis 3 is 1.1°, as Figures 1-2As shown, after the motor stator 803 is installed on the mounting surface 8011 of the mounting plate 801, the upper end of the motor stator 803 inclines backward, and the workpiece 1 is inclined on the workbench 1 by means of the inclination of the mounting surface 8011.

[0052] According to the different inclination angles of the channel holes 4 on different workpieces, an adaptable angle tooling 8 can be selected to realize the rapid adjustment of the angle of the workpiece on the workbench 7.

[0053] The cooling unit includes a liquid storage tank for supplying liquid to the internal cooling drill bit 2. The motor rotor 802 is a hollow tubular structure, as Figure 2 , Figure 3 and Figure 4 shown. A cooling sleeve 9 is provided on the mounting plate 801. The cooling sleeve 9 passes through the inner cavity of the motor rotor 802 and is arranged in contact with the workpiece 1 and corresponding to the channel hole 4 to be machined. The cooling sleeve 9 includes an outer side wall 901 and an inner side wall 902. An inlet water cavity 903 is formed between the outer side wall 901 and the inner side wall 902. Both ends of the inner side wall 902 are in contact with the workpiece 1. A drainage cavity 904 is formed between the inner side wall 902 and the workpiece 1. The output end of the inlet water cavity 903 is connected to the input end of the drainage cavity 904 and is close to the fixture 804. The input end of the inlet water cavity 903 and the output end of the drainage cavity 904 are respectively close to the mounting plate 801 and are respectively connected to the liquid storage tank by means of an inlet pipe and a drain pipe to form a circulation path of the coolant.

[0054] The workpiece 1 includes a mounting end and a shaft rod 101. Since there is more metal material at the mounting end of the workpiece 1, during machining, in addition to the coolant flowing out of the internal cooling drill bit 2 being able to take away most of the heat, the heat that is not taken away in time can be diffused in the mounting end in time, and the heat accumulation speed is slow, and it is not easy to generate too high a temperature at the mounting end; while a part of the shaft rod 101 has a thin wall and less metal material, and the heat generated by cutting is more likely to accumulate rapidly, resulting in a sharp rise in temperature, and the position with a thin wall is more likely to undergo thermal deformation, affecting the drilling accuracy. Therefore, a cooling sleeve 9 is added to assist in cooling the shaft rod 101 of the workpiece 1, further avoiding thermal deformation of the shaft rod 101 during machining and further ensuring the machining accuracy of the workpiece 1.

[0055] Among them, the coolant in the liquid storage tank enters the inlet water cavity 903 of the cooling sleeve 9 along the inlet pipe. As the coolant in the inlet water cavity 903 gradually increases, the coolant enters the drainage cavity 904 along the output end of the inlet water cavity 903 and flows from the side close to the fixture 804 towards the mounting plate 801 to cool the area of the workpiece 1 where the channel hole 4 is being machined in time.

[0056] A negative pressure water pump 10 is provided on the drain pipe. The negative pressure water pump 10 is signal-connected to the controller 6, and the start and stop of the negative pressure water pump 10 are controlled by the controller 6. When the negative pressure water pump 10 works, a negative pressure is generated in the drain pipe, and the coolant in the drainage cavity 904 is forcibly pumped out and returned to the liquid storage tank. Due to the existence of the negative pressure, the leakage of the coolant in the drainage cavity 904 along the workpiece 1 can also be effectively reduced.

[0057] The monitoring and compensation device 5 is a Renishaw on-line monitoring and compensation device.

[0058] The cooling unit further includes a liquid supply pipe and a thermostat 12. The liquid storage tank supplies liquid to the internal cooling drill bit 2 through the liquid supply pipe. A high-pressure water pump 11 is provided on the liquid supply pipe. The liquid inlet end of the liquid supply pipe is communicated with the liquid storage tank, and the liquid outlet end of the liquid supply pipe is connected to the tool shaft 3 through a high-pressure rotary joint. The thermostat 12 is connected to the liquid storage tank and adjusts the temperature of the coolant in the liquid storage tank. The high-pressure water pump 11 and the thermostat 12 are respectively signal-connected to the controller 6.

[0059] The controller 6 controls the thermostat 12 to turn on. After the coolant in the liquid storage tank is stabilized at 25 - 30 °C, the controller 6 controls the high-pressure water pump 11 to turn on. The high-pressure water pump 11 pumps out the coolant in the liquid storage tank and supplies it to the tool shaft 3 and the internal cooling drill bit 2, and ensures the pressure of supplying liquid to the internal cooling drill bit 2. The tool shaft 3 carries the internal cooling drill bit 2 to feed and process the workpiece. The coolant with high-pressure output effectively flushes and cools the internal cooling drill bit 2 and the cutting part, and can quickly discharge the chips from the processing area, thereby improving the processing quality. In this embodiment, the working pressure of the high-pressure water pump 11 is preferably 70 MPa.

[0060] For the 12-channel spindle processed by using this processing method and processing system, the position error of the spatial angular hole system is controlled within ±0.01 mm, meeting the international SEMI standard. The spindle dynamic balance grade reaches G0.4 level, the end face runout ≤1.5 μm, the temperature rise control ≤±0.8 °C / h. Finally, through the 72-hour continuous working condition verification of the customer, the yield rate reaches 99.6%, successfully realizing the import substitution and making an important breakthrough for the autonomy of the semiconductor equipment industry chain in our country.

Claims

1. A composite machining method for a high-precision multi-channel spindle of a semiconductor CMP device, characterized in that, It includes the following steps: S1. Clamp the workpiece (1) on the workbench (7); S2. Calibrate the accuracy of each axis of the workbench (7); S3. Use a tool setter to measure the length and diameter of the internal coolant drill bit (2) and establish tool compensation parameters; S4. Install the internal coolant drill bit (2) on the tool axis (3), and move the workpiece (1) to make the axis of the internal coolant drill bit (2) coincide with the axis of the channel hole (4) to be machined; S5. Connect the cooling unit to the internal coolant drill bit (2) and adjust the coolant output pressure in the cooling unit to be >60 MPA; S6. Start machining the channel hole (4) after controlling the coolant temperature to be stable at 25 - 30 °C; S7. Group the channel holes (4) on the workpiece (1). After machining each group of channel holes (4), trigger the monitoring and compensation device (5) to detect and trim the machining coordinates. After trimming the machining coordinates, machine the next group of channel holes (4) until the machining of each group of channel holes (4) is completed.

2. A processing system for implementing the composite processing method of the high-precision multi-channel spindle of a semiconductor CMP device according to claim 1, characterized in that: The system includes a tool axis (3), a cooling unit, and a monitoring and compensation device (5) that are respectively signal-connected to a controller (6). The workpiece (1) is clamped on the workbench (7) by means of an angle tooling (8). The axial direction of the workpiece (1) is set at an angle α with the axial direction of the tool axis (3). The axial direction of the channel hole (4) is set at an angle β with the axial direction of the workpiece (1). The angle α = the angle β. The workpiece (1) has degrees of freedom of movement along the X-axis, Y-axis, and Z-axis by means of the workbench (7). The internal coolant drill bit (2) is drivingly connected to the tool axis (3) and has a degree of freedom of reciprocating movement towards the workpiece (1).

3. A processing system according to claim 2, wherein: The angle tooling (8) includes a mounting plate (801), a motor rotor (802), a motor stator (803), and a fixture (804). The motor rotor (802) is configured to cooperate with the motor stator (803). The motor stator (803) is fixedly connected to the mounting plate (801). The fixture (804) is fixedly connected to the motor rotor (802). The workpiece (1) is clamped on the workbench (7) by means of the fixture (804) and has a degree of freedom of rotation by means of the cooperation between the motor rotor (802) and the motor stator (803).

4. A processing system according to claim 3, characterized in that: The described cooling unit includes a liquid storage tank for supplying liquid to the internal cooling drill bit (2). The motor rotor (802) is of a hollow tubular structure. A cooling sleeve (9) is provided on the mounting plate (801). The cooling sleeve (9) passes through the inner cavity of the motor rotor (802) and is arranged in contact with the workpiece (1) and corresponds to the channel hole (4) to be machined. The cooling sleeve (9) includes an outer side wall (901) and an inner side wall (902). An inlet water chamber (903) is formed between the outer side wall (901) and the inner side wall (902). Both ends of the inner side wall (902) are in contact with the workpiece (1), and a drainage chamber (904) is formed between the inner side wall (902) and the workpiece (1). The output end of the inlet water chamber (903) is connected to the input end of the drainage chamber (904) and is arranged close to the fixture (804). The input end of the inlet water chamber (903) and the output end of the drainage chamber (904) are respectively arranged close to the mounting plate (801) and are respectively connected to the liquid storage tank by means of an inlet pipe and a drain pipe to form a circulating path for the coolant.

5. A processing system according to claim 4, characterized in that: A negative pressure water pump (10) is provided on the described drain pipe, and the negative pressure water pump (10) is in signal connection with the controller (6).

6. A processing system according to claim 2, characterized in that: The described monitoring and compensation device (5) is a Renishaw on-line monitoring and compensation device.

7. A processing system according to claim 2, wherein: The cooling unit further includes a liquid supply pipe and a thermostat. The liquid storage tank supplies liquid to the internal cooling drill bit (2) by means of the liquid supply pipe. A high-pressure water pump (11) is provided on the liquid supply pipe. The liquid inlet end of the liquid supply pipe is communicated with the liquid storage tank, and the liquid outlet end of the liquid supply pipe is connected to the tool shaft (3) by means of a high-pressure rotary joint. The thermostat (12) is connected to the liquid storage tank and regulates the temperature of the coolant in the liquid storage tank. The high-pressure water pump (11) and the thermostat (12) are respectively in signal connection with the controller (6).

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