Electric spindle and numerical control machine tool with same

Abstract

The utility model provides a motorized spindle and a numerical control machine tool with the motorized spindle, the motorized spindle comprises a sleeve, the front end of the sleeve is provided with a front bearing supporting structure, the rear end of the sleeve is provided with a rear bearing supporting structure, a sleeve cooling flow channel is arranged in the sleeve, a front cooling flow channel is arranged in the front bearing supporting structure, and a rear cooling flow channel is arranged in the rear bearing supporting structure. The rear bearing supporting structure comprises a rear end seat and a rear bearing seat, and the rear end seat is arranged on the radial outer side of the rear bearing seat in a sleeving mode so that the rear cooling flow channel can be formed between the rear end seat and the rear bearing seat. The rear end seat is provided with a liquid inlet communicated with inlets of the sleeve cooling flow channel and the rear cooling flow channel and a liquid return port communicated with outlets of the sleeve cooling flow channel and the rear cooling flow channel, and the front cooling flow channel is communicated with the sleeve cooling flow channel. The structure is simple and compact, the number of parts needing to be machined and assembled is small, machining and assembling difficulty is lowered, and meanwhile production cost can be lowered.

Description

Technical Field

[0001] The utility model belongs to the technical field of cooling design, and particularly relates to an electric spindle and a numerical control machine tool having the same. Background Technique

[0002] The electric spindle is a new technology in the field of numerical control machine tools that combines a drive motor and a rotating spindle into one. Compared with traditional mechanical spindles, the electric spindle has the advantages of compact structure, low vibration and noise, stable machining performance, and high machining accuracy. With the continuous progress of science and technology, electric spindles with high precision, high speed, high stiffness, and high torque have emerged. Along with this is the increase in spindle heat, and the increase in heat will inevitably cause changes in the internal structure of the spindle. If the heat cannot be effectively cooled and the spindle temperature continues to rise, it will not only affect the machining accuracy of the spindle but also greatly reduce the service life of the spindle. The key component bearing will fail due to high temperature, which will affect the machining accuracy of the spindle at least and directly cause the spindle to jam and be scrapped at worst; the key component motor will burn out due to high temperature, resulting in the scrapping of the spindle; the key component shaft core will undergo thermal elongation deformation due to high temperature, ultimately resulting in poor machining accuracy of the spindle.

[0003] The existing spindle cooling method is to set cooling channels in the front bearing seat, the rear bearing seat, and other connected parts, and mostly adopts a series connection method to achieve through flowing coolant. However, this series cooling method results in uneven cooling of the front and rear bearing positions. The coolant first flows to the front bearing position and the motor position, and then flows to the rear bearing position. When it flows to the rear bearing position, the temperature of the coolant has increased, resulting in an unsatisfactory cooling effect at the rear end of the spindle. If the machine tool spindle processes parts for a long time, it will surely cause a large temperature rise at the rear end of the spindle, affecting the machining accuracy and service life of the spindle.

[0004] The patent with the publication number CN114309680 A adopts a full reciprocating cooling channel. Although it designs multiple liquid inlets and multiple liquid outlets, the cooling flow rate at the front and rear bearing positions is limited, and the cooling effect at the front and rear bearing positions is unsatisfactory. Long-term operation of the spindle will cause the temperature of the spindle bearing to rise, increasing the thermal elongation of the spindle and affecting the spindle accuracy. Excessive bearing temperature will cause the bearing to jam and lead to the scrapping of the spindle; the patent with the publication number CN115415845 A adopts a series cooling channel. The cooling channel first reciprocally cools the front bearing position, and then reciprocally cools the motor position and the rear bearing position. The series cooling channel has a large flow resistance, the flow rate is limited, and when it flows to the rear bearing position, the temperature of the coolant has increased, and the cooling effect at the rear bearing is unsatisfactory. The patent with the publication number CN212600628 U adopts a parallel connection method to cool the front and rear bearings separately, but it requires very complex cooling channels to be machined on the front and rear bearing seats, and multiple components need to cooperate to complete, resulting in great difficulty in machining and assembly. Content of the Utility Model

[0005] Therefore, the present utility model provides an electric spindle and a numerical control machine tool having the same, which can solve the problems in the prior art that the parallel cooling structure for the front and rear bearings of the electric spindle is complex, requires the cooperation and assembly of multiple components, and has a large assembly difficulty for the processing machine.

[0006] To solve the above problems, the present utility model provides an electric spindle, including a sleeve. The front end of the sleeve has a front bearing support structure, the rear end of the sleeve has a rear bearing support structure, the sleeve has a sleeve cooling flow channel therein, the front bearing support structure has a front cooling flow channel therein, the rear bearing support structure has a rear cooling flow channel therein. The front cooling flow channel and the rear cooling flow channel are in parallel. The rear bearing support structure includes a rear end seat and a rear bearing housing. The rear end seat is sleeved on the radial outer side of the rear bearing housing to form the rear cooling flow channel therebetween. The rear end seat has a liquid inlet communicating with the inlets of both the sleeve cooling flow channel and the rear cooling flow channel, and a liquid return port communicating with the outlets of the sleeve cooling flow channel and the rear cooling flow channel. The front cooling flow channel communicates with the sleeve cooling flow channel.

[0007] In some embodiments, the electric spindle further includes a pipeline plate. The rear end seat has an outer ring body, and the outer ring body is clamped between the pipeline plate and the rear end face of the sleeve. The pipeline plate has a cooling pipe inlet connected to an external liquid inlet pipe and a cooling pipe outlet connected to an external liquid return pipe. The liquid inlet is docked with the cooling pipe inlet, and the liquid return port is docked with the cooling pipe outlet.

[0008] In some embodiments, the rear end seat further has an inner ring body. The inner ring body is inserted into the central through hole of the sleeve and is sleeved and cooperated with the radial outer peripheral wall of the rear bearing housing to form the rear cooling flow channel. The liquid inlet and / or the liquid return port communicate with the rear cooling flow channel through radial flow channels respectively.

[0009] In some embodiments, a sealing ring is provided between the outer circumferential wall of the inner ring body and the wall of the central through hole of the sleeve; and / or, a sealing ring is provided between the inner circumferential wall of the inner ring body and the outer circumferential wall of the rear bearing housing.

[0010] In some embodiments, the front cooling flow channel is in series with the sleeve cooling flow channel.

[0011] In some embodiments, the front bearing support structure includes a front bearing water jacket and a convex ring formed on the front end face of the sleeve. The front bearing water jacket is sleeved on the outer circumferential wall of the convex ring to form the front cooling flow channel therebetween.

[0012] In some embodiments, the electric spindle further includes a front end cover. The front end cover is connected to the front end face of the sleeve, and the front bearing water jacket is clamped between the front end face of the sleeve and the front end cover.

[0013] In some embodiments, a plurality of first transfer grooves are formed on the end face of the front bearing water jacket that cooperates with the sleeve, and a plurality of second transfer grooves are formed on the end face of the rear end seat that cooperates with the sleeve. The sleeve cooling flow channel includes a plurality of axial flow channels that extend along the axial direction of the sleeve and penetrate through both axial ends thereof. Each of the first transfer grooves and the second transfer grooves connects the corresponding ports of two adjacent axial flow channels to enable the sleeve cooling flow channel to reciprocally turn back in the axial direction of the sleeve; and / or, a positioning structure is provided between the mating end face of the front bearing water jacket and the sleeve.

[0014] In some embodiments, inner retaining rings are provided in each of the first transfer grooves, the second transfer grooves, the liquid inlet, and the liquid return port.

[0015] The present utility model also provides a numerical control machine tool, including the above-mentioned motorized spindle.

[0016] A motorized spindle provided by the present utility model and a numerical control machine tool having the same have the following beneficial effects:

[0017] On the one hand, the front cooling flow channel and the rear cooling flow channel are in parallel, so that the front bearing and the rear bearing of the motorized spindle can be cooled simultaneously by using the coolant, preventing the occurrence of spindle failure problems caused by insufficient or untimely cooling of the rear bearing in the prior art, and improving the spindle stability and service life; on the other hand, the rear bearing support structure in the present utility model is formed by assembling the rear end seat and the rear bearing seat, and a rear cooling flow channel is formed between the two after assembly. The liquid inlet and the liquid return port are formed on the rear end seat, with a simple and compact structure, fewer components to be processed and assembled, reducing the processing and assembly difficulty while also being able to reduce the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. The drawings in the following description are merely exemplary, and those of ordinary skill in the art can also obtain other implementation drawings according to the provided drawings without creative efforts.

[0019] Figure 1 It is a schematic internal structure diagram of the motorized spindle according to an embodiment of the present utility model. What is shown in the figure is not a half-section of the motorized spindle, but a sectional view at a preset angle made to display the relevant structures of the liquid inlet and the liquid outlet on the same drawing;

[0020] Figure 2 It is a schematic structural diagram of the rear cooling flow channel in the rear bearing support structure of the motorized spindle according to an embodiment of the present utility model;

[0021] Figure 3 Is Figure 1 The three-dimensional structural schematic diagram of the rear end seat in Figure 1 at an angle (showing Figure 1 The left end face of

[0022] Figure 4 Is Figure 1 The three-dimensional structural schematic diagram of the rear end seat in Figure 1 at another angle (showing Figure 1 The right end face of

[0023] Figure 5 Is Figure 1 The three-dimensional structural schematic diagram of the rear bearing seat in Figure 1 ;

[0024] Figure 6 Is Figure 1 The three-dimensional structural schematic diagram of the front bearing water jacket in Figure 1 at an angle;

[0025] Figure 7 Is Figure 1 The three-dimensional structural schematic diagram of the front bearing water jacket in Figure 1 at another angle;

[0026] Figure 8 Is Figure 1 The schematic diagram of the connected flow of each cooling flow channel in the electric main shaft in Figure 1 .

[0027] Reference numerals are:

[0028] 1. Sleeve; 10. Sleeve cooling flow channel; 11. Convex ring; 20. Rear cooling flow channel; 21. Rear end seat; 211. Outer ring body; 212. Inner ring body; 213. Radial flow channel; 214. Second transfer groove; 215. Liquid inlet; 216. Liquid return port; 22. Rear bearing seat; 30. Front cooling flow channel; 31. Front bearing water jacket; 311. First transfer groove; 312. Positioning hole; 4. Pipe tray; 41. Cooling pipe inlet; 42. Cooling pipe outlet; 5. Front end cover; 6. Inner retaining ring; 7. Plug; 8. Sealing ring. Detailed implementation manners

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way restrictive of the present invention or its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0030] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description. Without contrary explanation, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present utility model; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0031] For the convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" etc. can be used here to describe the spatial positional relationship between a device or feature shown in the drawings and other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90° or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0032] In addition, it should be noted that using words such as "front", "rear", etc. to limit components is only for the convenience of differentiating the corresponding components. Without separate statement, the above words have no special meaning. Therefore, it should not be construed as a limitation on the protection scope of the present utility model.

[0033] See in conjunction with Figures 1 to 8As shown, according to an embodiment of the present utility model, there is provided an electric spindle, including a sleeve 1. The front end of the sleeve 1 has a front bearing support structure (not labeled in the figure), which has a front bearing position for assembling a front bearing (not shown in the figure). The rear end of the sleeve 1 has a rear bearing support structure (not labeled in the figure), which has a rear bearing position for assembling a rear bearing (not shown in the figure). The sleeve 1 has a sleeve cooling flow channel 10, and its central through hole has a motor position for assembling a motor (not shown in the figure). The front bearing support structure has a front cooling flow channel 30, and the rear bearing support structure has a rear cooling flow channel 20. The front cooling flow channel 30 and the rear cooling flow channel 20 are in parallel connection. The rear bearing support structure includes a rear end seat 21 and a rear bearing seat 22. The rear end seat 21 is sleeved on the radial outer side of the rear bearing seat 22 to form the rear cooling flow channel 20 therebetween. The rear end seat 21 has a liquid inlet 215 that is communicated with both the inlet of the sleeve cooling flow channel 10 and the rear cooling flow channel 20, and a liquid return port 216 that is communicated with the outlet of the sleeve cooling flow channel 10 and the rear cooling flow channel 20. The front cooling flow channel 30 is communicated with the sleeve cooling flow channel 10.

[0034] In this technical solution, on the one hand, the front cooling flow channel 30 and the rear cooling flow channel 20 are in parallel connection, so that the front bearing and the rear bearing of the electric spindle can be cooled simultaneously by using the coolant, preventing the occurrence of spindle failure problems caused by insufficient or untimely cooling of the rear bearing in the prior art, and improving the spindle stability and service life. On the other hand, the rear bearing support structure in the present utility model is formed by assembling the rear end seat 21 and the rear bearing seat 22, and a rear cooling flow channel 20 is formed between them after assembly. The liquid inlet 215 and the liquid return port 216 are formed on the rear end seat 21. The structure is simple and compact, and the number of parts that need to be processed and assembled is small, reducing the processing and assembly difficulty and also being able to reduce the production cost.

[0035] Specifically refer to Figure 1 As shown, in some embodiments, the electric spindle further includes a pipeline plate 4. The rear end seat 21 has an outer ring body 211, and the outer ring body 211 is clamped between the pipeline plate 4 and the rear end face of the sleeve 1. The pipeline plate 4 has a cooling pipe inlet 41 connected to an external liquid inlet pipe (not labeled in the figure) and a cooling pipe outlet 42 connected to an external liquid return pipe (not labeled in the figure). The liquid inlet 215 is docked with the cooling pipe inlet 41, and the liquid return port 216 is docked with the cooling pipe outlet 42. It can be understood that the aforementioned liquid inlet 215 and liquid return port 216 are both formed on the outer ring body 211. In a specific embodiment, the aforementioned pipeline plate 4 is connected to the rear end face of the sleeve 1 through screws passing through the outer ring body 211.

[0036] In this technical solution, the pipeline coil 4 is arranged on the rear end face of the rear end seat 21, which can form a reliable axial positioning of the rear end seat 21.

[0037] In some embodiments, the rear end seat 21 further has an inner ring body 212. Objectively, the inner ring body 212 and the outer ring body 211 can be integrally processed and formed. The inner ring body 212 is inserted into the central through hole of the sleeve 1, and is sleeved and matched with the radial outer peripheral wall of the rear bearing seat 22 to form the rear cooling flow channel 20. The liquid inlet 215 and / or the liquid return port 216 are respectively communicated with the rear cooling flow channel 20 through the radial flow channel 213.

[0038] In this technical solution, on the one hand, the inner ring body 212 serves as a connection and positioning structure between the rear end seat 21 and the central through hole of the sleeve 1, making the connection between the rear end seat 21 and the sleeve 1 more reliable. On the other hand, the inner wall surface of the inner ring body 212 forms the rear cooling flow channel 20 with the radial outer peripheral wall of the rear bearing seat 22, and the structure is very simple. The aforementioned rear cooling flow channel 20 is a circular flow channel in a specific embodiment. In order to prevent the leakage of the coolant in the rear cooling flow channel 20, in a preferred embodiment, sealing rings 8 (specifically O-ring seals) are provided between the mating surfaces of the rear bearing seat 22 and the inner ring body 212 and between the mating surfaces of the inner ring body 212 and the hole wall of the central through hole of the sleeve 1. That is, a sealing ring 8 is provided between the outer circumferential wall of the inner ring body 212 and the hole wall of the central through hole of the sleeve 1; and / or, a sealing ring 8 is provided between the inner circumferential wall of the inner ring body 212 and the outer circumferential wall of the rear bearing seat 22. In a relatively optimal embodiment, two circles of sealing rings 8 can be provided to form a double-sealing structure.

[0039] In a specific embodiment, the front cooling flow channel 30 is connected in series with the sleeve cooling flow channel 10. By connecting the front cooling flow channel 30 in series in the sleeve cooling flow channel 10, the structural design of the cooling flow channel can be simplified, and further, the circulation path of the coolant can be optimized, which is beneficial to improving the cooling effect.

[0040] Further referring to Figure 1 As shown, the front bearing support structure includes a front bearing water jacket 31 and a convex ring 11 formed on the front end face of the sleeve 1. In a specific embodiment, the aforementioned convex ring 11 and the sleeve 1 are an integrally formed structure. The front bearing water jacket 31 is sleeved on the outer circumferential wall of the convex ring 11 to form the front cooling flow channel 30 therebetween. The aforementioned front cooling flow channel 30 can specifically be a spiral flow channel. At this time, as Figure 1 As shown, spiral grooves are formed on the outer circumferential wall of the convex ring 11. When the front bearing water jacket 31 is sleeved on the outer circumferential wall of the convex ring 11, the notch of the spiral groove is sealed by the inner wall surface of the convex ring 11, thereby forming a sealed spiral flow channel.

[0041] In this technical solution, the front cooling channel 30 is formed by assembling the front bearing water jacket 31 and the convex ring 11 which are sleeved together, with a simple structure and convenient processing.

[0042] In another preferred embodiment, the motorized spindle further includes a front end cover 5, the front end cover 5 is connected to the front end face of the sleeve 1, and the front bearing water jacket 31 is clamped between the front end face of the sleeve 1 and the front end cover 5.

[0043] In this technical solution, by arranging the front end cover 5 on the end face of the front bearing water jacket 31 facing away from the sleeve 1, on the one hand, it can seal the ports of the connecting channels between the front cooling channel 30 and the sleeve cooling channel 10, and on the other hand, it can form a reliable axial limit for the front bearing water jacket 31, further reducing the number of components used, and thus further reducing the manufacturing cost of the motorized spindle.

[0044] In some embodiments, a plurality of first transfer grooves 311 are formed on the end face of the front bearing water jacket 31 that cooperates with the sleeve 1, and a plurality of second transfer grooves 214 are formed on the end face of the rear end seat 21 that cooperates with the sleeve 1. The sleeve cooling channel 10 includes a plurality of axial channels that extend along the axis of the sleeve 1 and penetrate through both ends of its axis. Each of the first transfer grooves 311 and the second transfer grooves 214 connects the corresponding ports of two adjacent axial channels to enable the sleeve cooling channel 10 to reciprocally turn back and forth in the axial direction of the sleeve 1. Specifically, with reference to Figure 4 and Figure 6 As shown, a total of five second transfer grooves 214 are provided on the front end face of the rear end seat 21, and a total of five first transfer grooves 311 are provided on the rear end face of the front bearing water jacket 31. The projections of each of the first transfer grooves 311 and the second transfer grooves 214 on the radial plane of the sleeve 1 have overlapping parts, and an axial channel corresponds to the overlapping part. In this way, each axial channel forms a reciprocating turn-back under the connection and transfer action of the first transfer grooves 311 and the second transfer grooves 214 at both ends thereof, thereby achieving efficient and comprehensive cooling of the motor at the motor position. In a specific embodiment, the shapes of the aforementioned first transfer grooves 311 and the second transfer grooves 214 can be arc-shaped grooves (or waist-shaped grooves) that extend along the circumferential direction of the sleeve 1 around the central axis of the sleeve 1.

[0045] Specifically, with reference to Figure 6 As shown, a positioning structure is provided between the mating end faces of the front bearing water jacket 31 and the sleeve 1. Specifically, the positioning structure can be a positioning hole 312 formed on the end face of the front bearing water jacket 31 facing the sleeve 1, and a positioning pin (not shown in the figure) corresponding to the positioning hole 312 is provided on the front end face of the sleeve 1.

[0046] Refer to in combination Figure 3 、 Figure 4 and Figure 6 As shown, in some embodiments, an inner retaining ring 6 is provided in each of the first transfer grooves 311, the second transfer grooves 214, the liquid inlet 215, and the liquid return port 216. The inner retaining ring 6 is generally a complete ring body (such as in the first transfer groove 311 and the second transfer groove 214 shown in Figure 4 and Figure 6 ), and in another operating condition, it can also be a ring body with a notch section (such as in the liquid inlet 215 and the liquid return port 216 shown in Figure 3 ). A mounting gap for the sealing ring is formed between the ring body and the corresponding groove wall, so as to prevent the leakage of the coolant caused by seal failure.

[0047] The following will describe in combination Figure 8 the entire cooling channel and the flow path of the coolant in the motorized spindle of the present utility model.

[0048] The coolant enters the spindle interior through the cooling tube inlet 41 of the pipeline disk 4 at the rear end of the motorized spindle. First, it is split at the liquid inlet 215 on the rear end seat 21 through the pipeline disk 4: one path enters the spiral channel of the rear bearing position (i.e., the aforementioned rear cooling channel 20) along the flow channel opened on the rear end seat 21. The rear end seat 21 is radially provided with a transfer channel (i.e., the aforementioned radial channel 213), and the coolant can enter the spiral channel of the rear bearing through the transfer channel to cool the rear bearing; then it flows back to the rear end seat 21 through another radial transfer channel and flows into the cooling tube outlet 42 on the pipeline disk 4 through the liquid return port 216 on the rear end seat 21, thus completing the efficient cooling of the rear bearing by the coolant; a plug 7 is installed at one end of each radial transfer channel to effectively prevent liquid leakage; the other path enters the spiral channel of the front bearing position (i.e., the aforementioned front cooling channel 30) along the axial through holes (i.e., the aforementioned axial channels) opened on the rear end seat 21 and the sleeve 1 to cool the front bearing assembly. A radial transfer channel is provided at the sleeve flange position (i.e., the aforementioned convex ring 11) ( Figure 1As shown (not indexed), the coolant can enter the spiral flow channel of the front bearing (i.e., the aforementioned front cooling flow channel 30) through the radial transfer flow channel. A plug 7 is installed at one end of each radial transfer flow channel to effectively prevent liquid leakage. Specifically, the rear coolant flows into the first annular cut groove at the front end of the sleeve, flows into the second annular cut groove through the notch on the shoulder of the front end of the sleeve, and then flows into the third cooling flow channel to complete the spiral cooling of the front bearing position; then through the radial transfer flow channel, it flows back to the axial through hole of the sleeve, turns through the first kidney-shaped groove (i.e., the aforementioned second transfer groove 214) on the rear end seat 21, and then flows into the first kidney-shaped groove (i.e., the aforementioned first transfer groove 311) of the front bearing water jacket 31 for turning to realize cooling of the motor stator installation position back and forth; finally, through the last (the fifth when five are provided) kidney-shaped groove of the front bearing water jacket 31, it flows out from the cooling pipe outlet 42 at the rear end of the main shaft to realize cooling of the bearing positions at the front and rear ends of the main shaft and the motor position.

[0049] According to an embodiment of the present invention, there is also provided a numerical control machine tool including the above-mentioned motorized spindle.

[0050] It is easily understood by those skilled in the art that, on the premise of no conflict, the advantageous technical features of the above various methods can be freely combined and superimposed.

[0051] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and variations can be made without departing from the technical principle of the present invention, and these improvements and variations should also be regarded as within the protection scope of the present invention.

Claims

1. An electric spindle, characterized in that: The invention comprises a sleeve (1), wherein the front end of the sleeve (1) has a front bearing support structure, the rear end of the sleeve (1) has a rear bearing support structure, the sleeve (1) has a sleeve cooling channel (10), the front bearing support structure has a front cooling channel (30), the rear bearing support structure has a rear cooling channel (20), the front cooling channel (30) and the rear cooling channel (20) are connected in parallel, and the rear bearing support structure comprises a rear end seat (21) and a rear bearing seat (22), The rear end seat (21) is mounted on the radial outer side of the rear bearing seat (22) to form the rear cooling channel (20) therebetween. The rear end seat (21) has a liquid inlet (215) connected to the inlets of the sleeve cooling channel (10) and the rear cooling channel (20), and a liquid return port (216) connected to the outlets of the sleeve cooling channel (10) and the rear cooling channel (20). The front cooling channel (30) is connected to the sleeve cooling channel (10).

2. The electric spindle according to claim 1, characterized in that: It also includes a pipeline disc (4), the rear end seat (21) having an outer ring body (211), the outer ring body (211) being clamped between the pipeline disc (4) and the rear end surface of the sleeve (1), the pipeline disc (4) having a cooling pipe inlet (41) connected to an external liquid inlet pipe and a cooling pipe outlet (42) connected to an external liquid return pipe, the liquid inlet (215) being connected to the cooling pipe inlet (41), and the liquid return port (216) being connected to the cooling pipe outlet (42).

3. The electric spindle according to claim 2, characterized in that: The rear end seat (21) also has an inner ring body (212), which is inserted into the central through hole of the sleeve (1) and is fitted with the radial outer peripheral wall of the rear bearing seat (22) to form the rear cooling channel (20), and the liquid inlet (215) and / or the liquid return port (216) are respectively connected to the rear cooling channel (20) through the radial channel (213).

4. The electric spindle according to claim 3, characterized in that: A sealing ring (8) is provided between the outer circumferential wall of the inner ring body (212) and the wall of the central through hole of the sleeve (1); and / or a sealing ring (8) is provided between the inner circumferential wall of the inner ring body (212) and the outer circumferential wall of the rear bearing seat (22).

5. The electric spindle according to claim 2, characterized in that: The front cooling channel (30) is connected in series with the sleeve cooling channel (10).

6. The electric spindle according to claim 5, characterized in that: The front bearing support structure comprises a front bearing water jacket (31) and a convex ring (11) formed on the front end surface of the sleeve (1); the front bearing water jacket (31) is sleeved on the outer circumferential wall of the convex ring (11) to form the front cooling channel (30) therebetween.

7. The electric spindle according to claim 6, characterized in that: It also includes a front end cover (5), the front end cover (5) is connected to the front end surface of the sleeve (1), and the front bearing water jacket (31) is clamped between the front end surface of the sleeve (1) and the front end cover (5).

8. The electric spindle according to claim 6, characterized in that: A plurality of first transition grooves (311) are formed on the end surface of the front bearing water jacket (31) that cooperates with the sleeve (1), and a plurality of second transition grooves (214) are formed on the end surface of the rear end seat (21) that cooperates with the sleeve (1). The sleeve cooling channel (10) includes a plurality of axial channels extending along the axial direction of the sleeve (1) and passing through both axial ends thereof, and each of the first transition grooves (311) and the second transition groove (214) connects the corresponding ports of two adjacent axial channels so that the sleeve cooling channel (10) can reciprocate in the axial direction of the sleeve (1); and / or, a positioning structure is provided between the mating end surfaces of the front bearing water jacket (31) and the sleeve (1).

9. The electric spindle according to claim 8, characterized in that: An inner retaining ring (6) is disposed in each of the first transfer groove (311), the second transfer groove (214), the liquid inlet (215), and the liquid return port (216).

10. A numerically controlled machine tool, characterized in that: The invention comprises the electric spindle according to any one of claims 1 to 9.

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