A central water outlet mechanism for a main shaft

Abstract

This invention discloses a central water outlet mechanism for a spindle. The spindle includes a tail cap and a pull rod, with the upper end of the pull rod extending into the tail cap. The central water outlet mechanism includes a rotary joint stator and a rotary joint mover. The rotary joint mover is fixed to the upper end of the pull rod and the two are interconnected. The rotary joint stator is located above the rotary joint mover, and a movable tube capable of sliding up and down passes through the rotary joint stator. A water inlet channel communicating with the upper end of the rotary joint stator is opened inside the tail cap. A water-retaining ring is fixed inside the tail cap and is sleeved on the outside of the pull rod, with the two rotating in cooperation. Multiple lateral drainage holes are opened on the side wall of the water-retaining ring, and an external water-gathering groove is opened on the outer side wall of the water-retaining ring. The lateral drainage holes communicate with the external water-gathering groove. A drainage channel communicating with the external water-gathering groove is opened inside the side wall of the tail cap. This invention can promptly drain the coolant seeping from the rotary joint, which is beneficial for the internal installation of the rotary joint on the spindle.

Description

Technical Field

[0001] This invention relates to spindles, and more particularly to a spindle with a built-in central water outlet mechanism. Background Technology

[0002] In the current field of spindle equipment, in order to reduce interference positions within the limited stroke of the machine tool and thus process larger parts, the spindle is usually required to have a center water outlet function. However, the rotary joint in existing center water outlet spindles is generally exposed externally. For relevant information, please refer to the Chinese patent publication document with announcement number CN210789254U and title "Support Structure of Rotary Joint for Water-Cooled High-Speed ​​Electric Spindle with Center Hole". In practical applications, for spindles with a rotary joint at the rear end, under long-term use conditions, coolant can easily seep out around the rotary joint. This seepage will prevent the rotary joint from being internally installed in the spindle. Therefore, how to prevent coolant seepage from the rotary joint from affecting the spindle performance is a technical problem that needs to be solved urgently in the existing technology. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a central water outlet mechanism that can promptly discharge coolant seeping from the rotary joint, which is beneficial for the spindle to be built into the rotary joint, in order to address the shortcomings of the prior art.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0005] A central water outlet mechanism for a spindle includes a tail cap and a pull rod. The upper end of the pull rod extends into the tail cap. The central water outlet mechanism includes a rotary joint stator and a rotary joint mover. The rotary joint mover is fixed to the upper end of the pull rod and the two are in communication. The rotary joint stator is located above the rotary joint mover. A movable tube capable of sliding up and down passes through the rotary joint stator. A water inlet channel communicating with the upper end of the rotary joint stator is opened in the tail cap. A water-retaining ring is fixed in the tail cap and sleeved on the outside of the pull rod. The rotating joint assembly has multiple lateral drainage holes on its side wall and an external water collection groove on its outer side wall. The lateral drainage holes are connected to the external water collection groove. The tail cover has a drainage channel connected to the external water collection groove in its side wall. When high-pressure coolant is introduced into the water inlet channel, the movable tube on the rotating joint assembly moves downward under pressure. The end face of the movable tube abuts against the end face of the moving part to form an end face seal. The leakage water generated during the downward movement of the movable tube and the moving part of the rotating joint is discharged outward in sequence through the lateral drainage holes, the external water collection groove and the drainage channel.

[0006] Preferably, the lower end of the movable tube is provided with a sealing ring, which is used to abut against the upper end of the rotary joint mover.

[0007] Preferably, the inner wall of the water-blocking ring is provided with an inner water-gathering groove, and the lateral drainage hole is connected to the inner water-gathering groove.

[0008] Preferably, the lower end of the water-blocking ring has an upwardly bent inner edge, and a narrow gap is provided between the inner edge and the pull rod.

[0009] Preferably, a rear waterproof cover is sealed and fixed on the inner side of the tail cover near the lower end, and a water-blocking sealing ring is fixed on the inner ring end of the rear waterproof cover. The pull rod passes through the water-blocking sealing ring and the two are rotatably engaged.

[0010] Preferably, the inner ring end of the water-blocking sealing ring has an upwardly protruding conical flange, which is sleeved on the outside of the pull rod.

[0011] Preferably, an annular pressure plate is fixed on the rear waterproof cover, and the outer ring end of the water-blocking sealing ring is pressed between the annular pressure plate and the rear waterproof cover.

[0012] Preferably, the annular pressure plate protrudes to one side of the water-blocking sealing ring to form multiple fan-shaped pressure platforms, which press against the outer ring end of the water-blocking sealing ring.

[0013] Preferably, the inner wall of the tail cap is provided with an inner cavity drain outlet that communicates with the drainage channel, and the inner cavity drain outlet is disposed adjacent to the rear end face of the rear waterproof cover.

[0014] Preferably, a cylinder seat is fixedly connected to the lower end of the tail cover, a cylinder is provided inside the cylinder seat, a piston is provided inside the cylinder, the pull rod passes through the piston rod of the piston, and an annular air passage is formed between the pull rod and the piston rod. A knife release limiting plate and a knife release tray are provided on the front side of the cylinder. The knife release tray is located outside the knife release limiting plate and a clearance gap is formed between the two. A rear cover is fixedly connected to the lower end of the cylinder seat. An air seal channel is opened in the side wall of the rear cover. The air seal channel, the inner cavity of the rear cover, the clearance gap and the annular air passage are connected in sequence. When airflow is injected into the air seal channel, the airflow passes through the air seal channel, the inner cavity of the rear cover, the clearance gap, the annular air passage and the inner side of the water-blocking sealing ring in sequence and exits, forming an air seal at the connection between the pull rod and the water-blocking sealing ring.

[0015] In the central water outlet mechanism of the spindle disclosed in this invention, the rotary joint stator and the rotary joint mover form a rotary joint assembly built into the tail cover. Regardless of whether the spindle is rotating or stationary, water pressure is generated when water is injected into the water inlet channel. Under the action of water injection pressure, the movable tube moves downward. At this time, the lower end face of the movable tube abuts against the upper end face of the rotary joint mover. At the same time, the movable tube and the rotary joint mover are interconnected. The water inlet channel can inject water into the tool holder at the front end through the pull rod, thereby realizing the flow of water from the middle of the spindle to the inside of the tool, which serves as a tool cooling function. During the above operation, because the present invention is equipped with the water-blocking ring, water that leaks out before the movable tube and the rotary joint mover come into contact during the connection process can be discharged outward in sequence through the side drain hole, the external water collection tank, and the drain channel. Compared with the prior art, the present invention can discharge the cooling water leaked from the rotary joint in a timely manner, effectively preventing the cooling water leaked from the rotary joint from affecting the spindle performance and better meeting the application requirements. Attached Figure Description

[0016] Figure 1 Sectional view along the main axis Figure 1 ;

[0017] Figure 2 Sectional view along the main axis Figure 2 ;

[0018] Figure 3 Partial section of the rear end of the main spindle Figure 1 ;

[0019] Figure 4 Here is a structural diagram of the rotor;

[0020] Figure 5 This is a cross-sectional view of the rotor;

[0021] Figure 6 This is a structural diagram of the ring spray plate;

[0022] Figure 7 Partial section of the rear end of the main spindle Figure 2 ;

[0023] Figure 8 Partial section of the rear end of the main spindle Figure 3 ;

[0024] Figure 9 This is a structural diagram of the water-retaining ring;

[0025] Figure 10 This is a cross-sectional view of the water-retaining ring;

[0026] Figure 11 This is a structural diagram of the rear waterproof cover;

[0027] Figure 12This is a cross-sectional view of the rear waterproof cover;

[0028] Figure 13 This is a structural diagram of the water-blocking sealing ring;

[0029] Figure 14 This is a structural diagram of a ring-shaped tablet. Detailed Implementation

[0030] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments.

[0031] Example 1

[0032] This embodiment proposes a central water outlet mechanism for the main shaft, combined with... Figure 1 , Figure 2 , Figure 3 , Figures 7 to 14 As shown, the main shaft includes a tail cover 6 and a pull rod 7. The upper end of the pull rod 7 extends into the tail cover 6. The central water outlet mechanism includes a rotary joint stator 60 and a rotary joint mover 61. The rotary joint mover 61 is fixed to the upper end of the pull rod 7 and the two are interconnected. The rotary joint stator 60 is located above the rotary joint mover 61. A movable tube 62 that can slide up and down is provided inside the rotary joint stator 60. A water inlet channel 63 communicating with the upper end of the rotary joint stator 60 is opened inside the tail cover 6. A water baffle ring 64 is fixed inside the tail cover 6. The water baffle ring 64 is sleeved on the outside of the pull rod 7 and the two are rotatably engaged. The side wall of the device has multiple lateral drainage holes 640, and the outer side wall of the water-blocking ring 64 has an outer water-gathering groove 641. The lateral drainage holes 640 are connected to the outer water-gathering groove 641. The side wall of the tail cover 6 has a drainage channel 600 connected to the outer water-gathering groove 641. When high-pressure coolant is introduced into the water inlet channel, the movable tube 62 on the rotary joint assembly is pressed and moves downward. The end face of the movable tube 62 abuts against the end face of the mover 61 to form an end face fit seal. The leakage water generated during the downward movement of the movable tube 62 and the rotary joint mover 61 is discharged outward in sequence through the lateral drainage holes 640, the outer water-gathering groove 641 and the drainage channel 600.

[0033] In the above structure, the rotary joint stator 60 and the rotary joint mover 61 form a rotary joint assembly built into the tail cover 6. Regardless of whether the spindle is rotating or stationary, water pressure is generated when water is injected into the water inlet channel 63. Under the action of water pressure, the movable tube 62 moves downward. At this time, the lower end face of the movable tube 62 abuts against the upper end face of the rotary joint mover 61. At the same time, the movable tube 62 and the rotary joint mover 61 are interconnected. The water inlet channel 63 can inject water into the front end of the tool holder through the pull rod 7. Water is used to achieve internal water cooling of the cutting tool. During the above operation, because the water-blocking ring 64 is provided in this invention, the water leaking from the connection between the movable tube 62 and the rotary joint mover 61 can be discharged outward in sequence through the lateral drain hole 640, the external water collection tank 641 and the drain channel 600. Compared with the prior art, this invention can promptly discharge the leaked cooling water generated before the stator and mover end faces of the rotary joint are properly fitted during water injection, effectively preventing the cooling water seeping from the rotary joint from affecting the spindle performance and better meeting the application requirements.

[0034] To achieve a sealed connection with the upper end of the rotary joint mover 61, in this embodiment, a sealing ring 620 is provided at the lower end of the movable tube 62. The sealing ring 620 is used to abut against the upper end of the rotary joint mover 61. Specifically, the sealing ring 620 is used to seal the movement gap of the movable tube 62 when water is flowing through it.

[0035] Combination Figure 9 and Figure 10 As shown, in this embodiment, an inner water-gathering groove corresponding to the outer water-gathering groove 641 is provided on the inner side of the water-blocking ring 64. Specifically, an inner water-gathering groove 642 is provided on the inner side wall of the water-blocking ring 64, and the lateral drainage hole 640 is connected to the inner water-gathering groove 642.

[0036] In the above structure, this embodiment provides water collection grooves on both the inner and outer sides of the water baffle ring 64, which helps to collect and discharge the cooling water leaking from the rotary joint in a timely manner.

[0037] To further enhance the water-blocking effect, in this embodiment, the lower inner side of the water-blocking ring 64 is formed with an upwardly bent inner edge 643, and a narrow gap is provided between the inner edge 643 and the pull rod 7.

[0038] Please see Figure 8 As a preferred embodiment, a waterproofing measure is preferably provided between the tail cover 6 and the pull rod 7. Specifically, a rear waterproof cover 65 is sealed and fixed on the inner side of the tail cover 6 near the lower end, and a water-blocking sealing ring 66 is fixed on the inner ring end of the rear waterproof cover 65. The pull rod 7 passes through the water-blocking sealing ring 66 and the two are rotatably engaged.

[0039] Furthermore, the inner ring end of the water-blocking sealing ring 66 is formed with an upwardly protruding conical flange 660, which is sleeved on the outside of the pull rod 7. The conical flange 660 effectively blocks water from seeping into the tail cap 6, thereby preventing cooling water from entering the main shaft along the pull rod 7.

[0040] To more reliably secure the water-blocking sealing ring 66, in this embodiment, an annular pressure plate 67 is fixed to the rear waterproof cover 65, and the outer ring end of the water-blocking sealing ring 66 is pressed between the annular pressure plate 67 and the rear waterproof cover 65. Furthermore, the annular pressure plate 67 protrudes towards the side facing the water-blocking sealing ring 66 to form multiple fan-shaped pressure platforms 670, which press against the outer ring end of the water-blocking sealing ring 66.

[0041] In the above structure, under the action of multiple fan-shaped pressure plates 670 on the annular pressure plate 67, the outer ring end of the water-blocking sealing ring 66 can be reliably pressed, so that the water-blocking sealing ring 66 and the pull rod 7 can be well matched.

[0042] In order to drain the cooling water that seeps into the inner cavity of the tail cover 6 in a timely manner, in this embodiment, the inner side wall of the tail cover 6 is provided with an inner cavity drain outlet 601 that communicates with the drainage channel 600, and the inner cavity drain outlet 601 is disposed adjacent to the rear end face of the rear waterproof cover 65.

[0043] Based on this, please see Figure 3 The lower end of the tail cap 6 is fixedly connected to a cylinder seat 8. A cylinder 83 is housed within the cylinder seat 8, and a piston 80 is housed within the cylinder 83. A pull rod 7 passes through the piston rod 800 of the piston 80, and an annular air passage 801 is formed between the pull rod 7 and the piston rod 800. A knife release limiting disc 81 and a knife release tray 82 are provided on the front side of the cylinder 83. The knife release tray 82 is located outside the knife release limiting disc 81, and a clearance gap 802 is formed between them. The lower end of the cylinder seat 8 is fixedly connected to... A rear cover 9 is fixedly connected, and an air-sealing channel 90 is provided in the side wall of the rear cover 9. The air-sealing channel 90, the inner cavity of the rear cover 9, the clearance gap 802 and the annular air passage 801 are connected in sequence. When airflow is injected into the air-sealing channel 90, the airflow passes through the air-sealing channel 90, the inner cavity of the rear cover 9, the clearance gap 802, the annular air passage 801 and the inner side of the water-blocking sealing ring 66 in sequence, and forms an air seal at the connection between the pull rod 7 and the water-blocking sealing ring 66.

[0044] In the above structure, when the spindle enters the working state, airflow can be injected through the air seal channel 90. The airflow passes through the air seal channel 90, the inner cavity of the rear cover 9, the clearance gap 802, the annular air passage 801, and the water-blocking sealing ring 66 in sequence. An annular air seal is formed between the inner side of the water-blocking sealing ring 66 and the pull rod 7. This annular air seal is used to prevent water that has seeped into the rear cover 9 from entering the spindle along the pull rod 7, thereby playing a further role in air sealing and water blocking, and significantly improving the waterproof and water-blocking characteristics of the spindle.

[0045] Example 2

[0046] This embodiment proposes a main shaft with a built-in central water outlet mechanism, combined with... Figures 1 to 6 As shown, it includes a steel cylinder 1, with a front bearing seat 2 and a rear bearing seat 3 fixed at both ends of the steel cylinder 1, respectively. A front bearing assembly 20 is housed inside the front bearing seat 2, and a rear bearing assembly 30 is housed inside the rear bearing seat 3. A rotor 4 is housed inside the steel cylinder 1, with both ends of the rotor 4 passing through the front bearing assembly 20 and the rear bearing assembly 30, respectively. A hollow pull rod 7 passes through the rotor 4. A tool holder 70 connected to the pull rod 7 is located at the front end of the rotor 4. A tool holder water channel 71 is formed inside the tool holder 70. A rear cover 9 is fixed to the upper end of the rear bearing assembly 30, and the upper end of the rotor 4 is located inside the rear cover 9. A hydraulic cylinder seat 8 is fixed to the upper end of the rear cover 9, and a hydraulic cylinder seat 8 is provided inside the hydraulic cylinder seat 8. A sliding hydraulic cylinder 83 has a piston 80 inside, and a piston rod 800 is located at the center of the piston 80. The upper end of the pull rod 7 passes through the piston rod 800. A tail cover 6 is fixed to the upper end of the hydraulic cylinder seat 8. A water inlet channel 63 is opened inside the tail cover 6. A rotary joint assembly 69 is located inside the tail cover 6. The rotary joint assembly 69 is located between the water inlet channel 63 and the upper end of the pull rod 7. When high-pressure water is introduced into the water inlet channel 63, the movable tube 62 of the rotary joint assembly 69 abuts against the end face of the mover 61 to form a connection, so that the injected cooling water is transported sequentially through the water inlet channel 63, the rotary joint assembly 69, the pull rod 7, and the tool holder water channel 71.

[0047] In the above structure, the bearing assemblies at the front and rear ends of the steel cylinder 1, the rotor 4, the tie rod 7, and the hydraulic cylinder assembly form the basic structure of the spindle. Based on this, the present invention fixes a tail cover 6 to the upper end of the hydraulic cylinder seat 8, and a rotary joint assembly 69 is built into the tail cover 6. A water inlet channel 63 is also provided within the tail cover 6. When the spindle is in the tool-clamping state or the tool-free clamping state, cooling water is injected into the water inlet channel 63, connecting the rotary joint assembly 69 between the water inlet channel 63 and the upper end of the tie rod 7. At this time, the cooling water injected through the water inlet channel 63 is discharged outwards sequentially through the water inlet channel 63, the rotary joint assembly 69, the tie rod 7, and the tool holder water channel 71, thereby achieving water cooling for the tool holder 70 and the tool tip. Compared with the prior art, the present invention not only achieves center-outlet water cooling, but also integrates the rotary joint assembly 69 inside the spindle by embedding it within the tail cover 6, thus avoiding stress on the rotary joint assembly during use and helping to improve the overall performance of the spindle.

[0048] Regarding the specific structure of the hydraulic cylinder assembly, in this embodiment, a cylinder cover 830 is fixed to the upper end of the hydraulic cylinder 83, and the piston 80 is disposed within the hydraulic cavity formed by the cylinder cover 830 and the hydraulic cylinder 83. Further, a first hydraulic connector 91 and a second hydraulic connector 92 are fixed to the upper end of the rear cover 9. The first hydraulic connector 91 communicates with the upper cavity of the piston 80, and the second hydraulic connector 92 communicates with the lower cavity of the piston 80.

[0049] Combination Figure 1 and Figure 3 As shown, this embodiment also has the function of automatically locking the rotor after tool release. Specifically, the front side of the hydraulic cylinder 83 is provided with a tool release limiting plate 81 and a tool release tray 82. The tool release tray 82 is fixedly connected to the lower end of the hydraulic cylinder 83, and the tool release limiting plate 81 is fixedly connected to the upper end of the rotor 4. A locking ring 820 is formed on the inner ring end of the tool release tray 82. The locking ring 820 is located below the tool release limiting plate 81. When the spindle performs the tool release action, hydraulic oil is injected into the upper cavity of the piston 80 to drive the rotor 4. The piston 80 and the pull rod 7 move downwards, and under the reaction force of the hydraulic oil, push the cylinder 83 and the tool release tray 82 upwards until the locking ring 820 locks with the tool release limiting plate 81. When the spindle performs the tool clamping action, hydraulic oil is injected into the cavity below the piston 80 to drive the piston 80 and the pull rod 7 upwards. Under the reaction force of the hydraulic oil, the cylinder 83 and the tool release tray 82 are pushed downwards until the tool release tray 82 separates from the tool release limiting plate 81.

[0050] In the above structure, a tool release tray 82 is fixedly installed at the lower end of the oil cylinder 83, which can lock and match the tool release limiting plate 81. When the user needs to change the tool, the tool release action needs to be performed on the spindle. Hydraulic oil is injected into the upper cavity of the piston 80 through the hydraulic source. Under the action of hydraulic oil pressure, the piston 80 and the pull rod 7 are driven to move downward. Because there is a reaction force in the hydraulic oil, the reaction force will push the oil cylinder 83 and the tool release tray 82 to rise. Finally, the locking ring 820 is locked to the tool release limiting plate 81, so that the rotor 4 cannot rotate. Furthermore, when the tool change is complete and the spindle needs to perform the tool clamping action, hydraulic oil can be injected into the lower cavity of the piston 80 via a hydraulic source. This drives the piston 80 and the pull rod 7 to move upwards. The reaction force of the hydraulic oil pushes the cylinder 83 and the tool release tray 82 downwards, causing the tool release tray 82 to separate from the tool release limiting plate 81. At this point, the rotor 4 can automatically rotate and enter the working state. Based on the above principle, this embodiment achieves automatic locking and automatic opening of the rotor 4 during the tool release and clamping process. This not only improves the reliability of the tool change process but also avoids stress on the bearings at the front and rear ends of the rotor 4.

[0051] Combination Figure 1 and Figure 3 As shown, the rotary joint assembly 69 in this embodiment includes a rotary joint stator 60 and a rotary joint mover 61. The rotary joint mover 61 is fixed to the upper end of the pull rod 7 and the two are connected to each other. The rotary joint stator 60 is located above the rotary joint mover 61. A movable tube 62 that can slide up and down is provided inside the rotary joint stator 60. A water inlet channel 63 that communicates with the upper end of the rotary joint stator 60 is provided inside the tail cap 6.

[0052] Combination Figure 1 and Figure 2As shown, in order to form an annular air seal at the front end of the spindle, in this embodiment, a front bearing pressure plate 10 is fixed to the lower end of the front bearing housing 2, a dustproof ring 11 is fixed to the lower end of the front bearing pressure plate 10, and an annular spray plate 12 is fixed to the lower end of the dustproof ring 11. A rotor outer sleeve 13 and a front waterproof cover 15 are fixed to the outer side of the rotor 4. A first gap 14 is formed between the rotor outer sleeve 13 and the front bearing pressure plate 10, the dustproof ring 11, and the annular spray plate 12. The front waterproof cover 15 is located on the rotor outer sleeve 1. Below 3, an air seal gap 16 is formed between the front waterproof cover 15 and the annular spray plate 12. The rear cover 9, the steel cylinder 1, the front bearing seat 2, the front bearing pressure plate 10 and the dustproof ring 11 are provided with air seal air passages 17 connected in sequence. An air passage connector 93 is provided at the upper end of the rear cover 9. The air passage connector 93, the air seal air passage 17, the first gap 14 and the air seal gap 16 are connected in sequence. The airflow injected by the air passage connector 93 passes through the air seal gap 16 and forms an annular air seal.

[0053] To facilitate airflow into the first gap 14, in this embodiment, an annular gas storage and pressure stabilizing cavity 120 is formed at the lower edge of the annular spray plate 12. The annular gas storage and pressure stabilizing cavity 120 is connected to the gas seal passage 17. An air passage groove 121 is formed on the lower end surface of the annular spray plate 12. The air passage groove 121 is connected between the annular gas storage and pressure stabilizing cavity 120 and the first gap 14.

[0054] Please see Figure 6 To ensure uniform airflow distribution, in this embodiment, the lower end face of the annular spray plate 12 is provided with a plurality of air passage grooves 121, which are evenly distributed along the circumference of the annular spray plate 12.

[0055] As a preferred embodiment, the rear cover 9 has an adjustment hole 94 on its side, and a dynamic balance adjustment ring 95 is provided inside the rear cover 9. The dynamic balance adjustment ring 95 is sleeved on the rotor 4 and the two are fixedly connected. An adjustment screw hole 96 is provided on the outer side of the dynamic balance adjustment ring 95, and the adjustment screw hole 96 is aligned with the adjustment hole 94. In this embodiment, by providing an adjustment hole 94, it is beneficial for the user to directly adjust the dynamic balance adjustment screw in the adjustment screw hole 96 from the outside without disassembling the spindle. This not only facilitates the debugging work, but also avoids the adverse effects caused by repeated disassembly and assembly.

[0056] Combination Figure 4 and Figure 5As shown, regarding the preferred structure of the rotor 4, in this embodiment, a rotor core 40, a front balancing ring 41, and a rear balancing ring 42 are fixed on the rotor 4, with the front balancing ring 41 and the rear balancing ring 42 respectively located at both ends of the rotor core 40. Further, four magnetic guide slots 43 are formed within the rotor core 40, and multiple magnetic steel sheets 44 are embedded within the rotor core 40 between adjacent magnetic guide slots 43.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the technical scope of the present invention should be included within the scope of protection of the present invention.

Claims

1. A central water outlet mechanism for a main shaft, the main shaft comprising a tail cap (6) and a pull rod (7), the upper end of the pull rod (7) extending into the tail cap (6), characterized in that, The central water outlet mechanism includes a rotary joint stator (60) and a rotary joint mover (61). The rotary joint mover (61) is fixed to the upper end of the pull rod (7) and the two are interconnected. The rotary joint stator (60) is located above the rotary joint mover (61). A movable tube (62) capable of sliding up and down is provided inside the rotary joint stator (60). A water inlet channel (63) communicating with the upper end of the rotary joint stator (60) is provided inside the tail cap (6). (6) A water-blocking ring (64) is fixed inside. The water-blocking ring (64) is sleeved on the outside of the pull rod (7) and the two are rotatably engaged. The side wall of the water-blocking ring (64) is provided with a plurality of lateral drainage holes (640). The outer side wall of the water-blocking ring (64) is provided with an outer water-gathering groove (641). The lateral drainage holes (640) are connected to the outer water-gathering groove (641). The side wall of the tail cap (6) is provided with a drainage channel (600) connected to the outer water-gathering groove (641). When the water-blocking ring (6) is inserted into the tail cap (6), a drainage channel (600) is provided inside the tail cap (6) that is connected to the outer water-gathering groove (641). When high-pressure coolant is introduced into the water channel, the movable tube (62) on the rotary joint assembly moves downward under pressure. The end face of the movable tube (62) abuts against the end face of the rotary joint mover (61) to form an end face seal. During the downward movement of the movable tube (62) and the rotary joint mover (61), the leaking water is discharged outward in sequence through the side drain hole (640), the outer water collection groove (641), and the drain channel (600). The inner wall of the water baffle ring (64) is provided with an inner water collection groove (600). 42), the side drain hole (640) is connected to the inner water tank (642); the inner side of the lower end of the water baffle ring (64) has an upwardly bent inner edge (643), and a narrow gap is provided between the inner edge (643) and the pull rod (7); the rear waterproof cover (65) is sealed and fixed on the inner side of the tail cover (6) near the lower end, and a water baffle sealing ring (66) is fixed on the inner ring end of the rear waterproof cover (65), and the pull rod (7) passes through the water baffle sealing ring (66) and the two are rotated together.

2. The central water outlet mechanism of the main shaft as described in claim 1, characterized in that, The lower end of the movable tube (62) is provided with a sealing ring (620), which is used to abut against the upper end of the rotary joint mover (61).

3. The central water outlet mechanism of the main shaft as described in claim 1, characterized in that, The inner ring end of the water-blocking sealing ring (66) is formed with an upwardly protruding conical flange (660), which is sleeved on the outside of the pull rod (7).

4. The central water outlet mechanism of the main shaft as described in claim 3, characterized in that, An annular pressure plate (67) is fixed on the rear waterproof cover (65), and the outer ring end of the water-blocking sealing ring (66) is pressed between the annular pressure plate (67) and the rear waterproof cover (65).

5. The central water outlet mechanism of the main shaft as described in claim 4, characterized in that, The annular pressure plate (67) protrudes towards the side of the water-blocking sealing ring (66) to form a plurality of fan-shaped pressure platforms (670), which press the outer ring end of the water-blocking sealing ring (66).

6. The central water outlet mechanism of the main shaft as described in claim 5, characterized in that, The inner wall of the tail cap (6) is provided with an inner cavity drain outlet (601) that communicates with the drainage channel (600), and the inner cavity drain outlet (601) is arranged adjacent to the rear end face of the rear waterproof cover (65).

7. The central water outlet mechanism of the main shaft as described in claim 6, characterized in that, The lower end of the tail cap (6) is fixedly connected to a cylinder seat (8), a cylinder (83) is provided inside the cylinder seat (8), a piston (80) is provided inside the cylinder (83), a pull rod (7) passes through the piston rod (800) of the piston (80), and an annular air passage (801) is formed between the pull rod (7) and the piston rod (800). A knife release limiting plate (81) and a knife release tray (82) are provided on the front side of the cylinder (83). The knife release tray (82) is located outside the knife release limiting plate (81), and a clearance gap (802) is formed between the two. The cylinder seat (8) A rear cover (9) is fixedly connected to the lower end. An air seal channel (90) is provided in the side wall of the rear cover (9). The air seal channel (90), the inner cavity of the rear cover (9), the clearance gap (802) and the annular air passage (801) are connected in sequence. When air is injected into the air seal channel (90), the air flow passes through the air seal channel (90), the inner cavity of the rear cover (9), the clearance gap (802), the annular air passage (801) and the inner side of the water-blocking sealing ring (66) in sequence, and forms an air seal at the connection between the pull rod (7) and the water-blocking sealing ring (66).

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