Electric spindle and numerical control machine tool

Abstract

The invention provides an electric spindle and a numerical control machine tool, the electric spindle comprises a shaft sleeve, a first end of the shaft sleeve is provided with a bearing seat, two end faces of the bearing seat are respectively a shunting surface and an entering surface, the shunting surface is provided with a first arc-shaped groove, and the first arc-shaped groove extends along the circumferential direction of the shaft sleeve; a first inlet hole is formed in the bearing seat, and an outlet of the first inlet hole leads to the first arc-shaped groove; a plurality of first water inlet holes extending in the axial direction are formed in the side wall of the shaft sleeve, inlets of the first water inlet holes are formed in the end face of the first end of the shaft sleeve, and the first arc-shaped grooves cover the inlets of the first water inlet holes, so that the problems that in the prior art, the flowing resistance of cooling liquid is large, and the cooling effect is poor can be solved. And the cooling of the electric spindle is not uniform.

Description

Technical Field

[0001] The invention belongs to the technical field of electric spindles, and in particular relates to an electric spindle and a numerically controlled machine tool. Background Art

[0002] The electric spindle is a spindle that integrates the spindle motor and the machine tool spindle. The electric spindle is often used in the field of intelligent equipment CNC machine tools. During operation, the motor and bearings inside the spindle will generate a lot of heat. If the electric spindle is not cooled down in time, the bearings and motor will be damaged, which will not only affect the spindle accuracy, but also greatly reduce the service life of the spindle.

[0003] In the prior art, a series connection is often used to cool the front bearing, motor stator and rear bearing in sequence. This cooling method has only a single water inlet and outlet channel, which not only increases the flow resistance of the coolant and reduces the flow speed of the coolant, but also causes uneven overall temperature of the electric spindle due to the gradual increase in the temperature of the coolant during the flow process, affecting the equipment life and processing accuracy.

[0004] How to reduce the flow resistance of the coolant and cool the electric spindle more evenly is a technical problem that needs to be solved urgently. Summary of the invention

[0005] Therefore, the present invention provides an electric spindle and a CNC machine tool, which can solve the technical problems in the prior art that the flow resistance of the coolant is large and the temperature of the electric spindle is uneven.

[0006] In one aspect, the present invention provides an electric spindle, comprising a sleeve, a first end of the sleeve being provided with a bearing seat, two end faces of the bearing seat being respectively a flow dividing face and an entrance face, the flow dividing face being provided with a first arcuate groove, the first arcuate groove extending along the circumferential direction of the sleeve; a first entrance hole being provided on the bearing seat, the outlet of the first entrance hole leading to the first arcuate groove;

[0007] A plurality of first water inlet holes extending along the axial direction are arranged in the side wall of the sleeve, the inlets of the first water inlet holes are arranged on the end surface of the first end of the sleeve, and the first arc groove covers the inlets of the plurality of first inlet holes.

[0008] In some embodiments, a water outlet is provided in the side wall of the sleeve, a flange is provided at the second end of the sleeve, an annular groove is provided between the flange and the end surface of the second end of the sleeve, and the outlet of the first water inlet and the inlet of the water outlet both lead to the annular groove.

[0009] In some embodiments, there are multiple water outlet holes, a second arc-shaped groove is provided on the diverter surface, outlets of the multiple water outlet holes lead to the second arc-shaped groove, and the second arc-shaped groove is connected to the inlet surface through the first outflow hole.

[0010] In some embodiments, only one water outlet hole is provided, and the water outlet hole and the plurality of first water inlet holes are evenly distributed along the circumference of the sleeve; the outlet of the water outlet hole is provided on the end surface of the first end of the sleeve, a second outflow hole is provided on the bearing seat, the inlet of the second outflow hole is provided on the diverter surface, the outlet is provided on the inlet surface, and the outlet of the water outlet hole is connected to the inlet of the second outflow hole.

[0011] In some embodiments, a third arcuate groove is provided on the diverter surface, and the third arcuate groove is connected to the entry surface via a second entry hole. A plurality of second water inlet holes are also provided in the side wall of the sleeve, and the inlets of the plurality of second water inlet holes are provided on the end surface of the first end of the sleeve, and the third arcuate groove covers the plurality of third arcuate grooves.

[0012] In some embodiments, a first seal is disposed between the diverter surface and an end surface of the first end of the sleeve; and a second seal is disposed between the flange and an end surface of the second end of the sleeve.

[0013] In some embodiments, a first bearing position is disposed in the bearing seat, an annular cavity is disposed in the bearing seat, the annular cavity surrounds the first bearing position, and the annular cavity is connected to the first entry hole via a connecting hole.

[0014] In some embodiments, a second bearing seat is disposed on the inner wall surface of the second end of the sleeve.

[0015] In some embodiments, when an annular groove is provided, the annular groove is provided on the end surface of the second end of the sleeve, and the depth of the annular groove along the axial direction of the sleeve can cover a portion of the second bearing position.

[0016] The invention also provides a numerically controlled machine tool, comprising the electric spindle.

[0017] The present invention arranges a plurality of first water inlet holes on the shaft sleeve, and the external cooling water first flows into the first arc-shaped groove through the first inlet holes. In the first arc-shaped groove, the cooling liquid can flow into the plurality of first water inlet holes on the one hand, and on the other hand, the first arc-shaped groove increases the heat exchange area between the cooling liquid and the bearing seat, improves the cooling effect of the cooling liquid on the bearing seat, and is beneficial to the cooling of the bearing in the bearing seat. Since there are a plurality of first water inlet holes and they are arranged in parallel, the cooling liquid enters the first water inlet holes at the same time, and the flow resistance is reduced, which is beneficial to the increase of the flow speed of the liquid. The temperature difference of the cooling liquid at both ends of the first water inlet hole is small, which is beneficial to ensure the overall temperature balance of the shaft sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0019] Figure 1 is a cross-sectional view of an electric spindle according to an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of a shaft sleeve according to an embodiment of the present invention provided with a plurality of water outlet holes;

[0021] Figure 3 The embodiment of the present invention Figure 2 Radial cross-sectional view of the middle shaft sleeve;

[0022] Figure 4 It is a schematic diagram of the structure of the first inlet hole, the first arc-shaped groove, the first water inlet hole, the annular groove, the water outlet hole, the second arc-shaped groove and the first outflow hole in an embodiment of the present invention;

[0023] Figure 5 is a schematic diagram of a bearing seat provided with a second arc groove in an embodiment of the present invention;

[0024] Figure 6 The embodiment of the present invention Figure 5 A schematic axial view of the bearing seat facing the entry surface;

[0025] Figure 7 is an axial schematic diagram of the first end when the shaft sleeve of an embodiment of the present invention is provided with a plurality of water outlet holes;

[0026] Figure 8 is a schematic diagram of a shaft sleeve of an embodiment of the present invention when only one water outlet hole is provided;

[0027] Fig. 9 The embodiment of the present invention Figure 8 A radial cross-sectional view of the middle bushing;

[0028] Fig.10 It is a schematic diagram of the structure of the first inlet hole, the second inlet hole, the first arc-shaped groove, the third arc-shaped groove, the first water inlet hole, the second water inlet hole, the annular groove, and the water outlet hole in an embodiment of the present invention;

[0029] Fig.11 is a schematic diagram of a bearing seat provided with a third arc groove in an embodiment of the present invention;

[0030] Fig.12 The embodiment of the present invention Fig.11 A schematic axial view of the bearing seat facing the entry surface;

[0031] Fig.13 is a first end axial schematic diagram of a shaft sleeve of an embodiment of the present invention when only one water outlet hole is provided;

[0032] The accompanying drawings are marked as follows:

[0033] 1. Bushing; 101. First water inlet hole; 102. Second water inlet hole; 103. Annular groove; 2. Bearing seat; 201. First arc groove; 202. Second arc groove; 203. Third arc groove; 2041. First inlet hole; 2042. Second inlet hole; 2051. First outflow hole; 2052. Second outflow hole; 206. Diverter surface; 207. Inlet surface; 208. Water outlet hole; 209. Annular cavity; 210. Connecting hole; 3. Flange; 401. First sealing member; 402. Second sealing member; 501. First bearing position; 502. Second bearing position; 5011. Rear bearing; 5021. Front bearing; 6. Stator; 7. Shaft core. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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 is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0036] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0037] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0038] See also Figure 1-13 As shown, an electric spindle provided by the present invention comprises a sleeve 1, a first end of the sleeve 1 is provided with a bearing seat 2, two end faces of the bearing seat 2 are respectively a flow dividing surface 206 and an entrance surface 207, the flow dividing surface 206 is provided with a first arcuate groove 201, and the first arcuate groove 201 extends along the circumferential direction of the sleeve 1; a first entrance hole 2041 is provided on the bearing seat 2, and an outlet of the first entrance hole 2041 leads to the first arcuate groove 201;

[0039] The side wall of the sleeve 1 is provided with a plurality of first water inlet holes 101 extending along the axial direction. The inlet of the first water inlet holes 101 is provided on the end surface of the first end of the sleeve 1 . The first arc groove 201 covers the inlet of the plurality of first inlet holes 2041 .

[0040] By arranging a plurality of first water inlet holes 101 on the shaft sleeve 1, the external cooling water first flows into the first arc groove 201 through the first inlet hole 2041. In the first arc groove 201, the cooling liquid can flow into the plurality of first water inlet holes 101 on the one hand, and on the other hand, the first arc groove 201 increases the heat exchange area between the cooling liquid and the bearing seat 2, improves the cooling effect of the cooling liquid on the bearing seat 2, and is beneficial to the cooling of the bearing in the bearing seat 2. Since there are a plurality of first water inlet holes 101 and they are arranged in parallel, the cooling liquid enters the first water inlet holes 101 at the same time, the flow resistance is reduced, which is beneficial to the increase of the flow speed of the liquid, and the temperature difference of the cooling liquid at both ends of the first water inlet hole 101 is small, which is beneficial to ensure the overall temperature balance of the shaft sleeve 1, thereby improving the working accuracy and life of the electric spindle.

[0041] The first water inlet hole 101 is arranged in the shaft sleeve 1, and there is no need to install an additional water jacket of the motor stator 6, so the structure is simple and the processing difficulty is low.

[0042] The stator 6 is fixed to the inner wall surface of the sleeve 1 , and when the temperature of the sleeve 1 is reduced, the temperature of the stator 6 is also reduced.

[0043] “Plurality” includes “two”.

[0044] Preferably, Figure 2-4 As shown in Figures 7-10, a water outlet hole 208 is provided in the side wall of the sleeve 1, a flange 3 is provided at the second end of the sleeve 1, an annular groove 103 is provided between the flange 3 and the end surface of the second end of the sleeve 1, and the outlet of the first water inlet hole 101 and the inlet of the water outlet hole 208 both lead to the annular groove 103.

[0045] By providing an annular groove 103 between the flange 3 and the second end of the sleeve 1, on the one hand, the coolant flowing out of the first water inlet hole 101 can enter the annular groove 103 to cool the second end of the sleeve 1 and the flange 3 more comprehensively, and on the other hand, the annular groove 103 also connects the first water inlet hole 101 and the water outlet hole 208. The coolant enters the annular groove 103 and then enters the water outlet hole 208, and flows out from the water outlet hole 208. Since the water outlet hole 208 is provided on the side wall of the sleeve 1, the coolant flowing in the water outlet hole 208 can cool the sleeve 1 again, thereby further improving the cooling effect on the sleeve 1.

[0046] Preferably, Figure 2-4 As shown, there are multiple water outlet holes 208, and a second arc-shaped groove 202 is provided on the diverter surface 206. The outlets of the multiple water outlet holes 208 lead to the second arc-shaped groove 202, and the second arc-shaped groove 202 is connected to the inlet surface 207 through the first outflow hole 2051.

[0047] By providing a plurality of water outlet holes 208, on the one hand, the flow resistance of the coolant in the water outlet hole 208 can be reduced, and the flow speed of the coolant in the first water inlet hole 101 and the water outlet hole 208 can be increased; on the other hand, the distribution of the coolant flowing from the annular groove 103 into the water outlet hole 208 can be made more uniform, so that the overall temperature of the shaft sleeve 1 is cooled more evenly, and the working accuracy of the electric spindle is improved. After the coolant flows out of the plurality of water outlet holes 208, it is collected in the second arc groove 202, and the coolant cools the bearing seat 2 in the second arc groove 202, so that the bearing seat 2 can be cooled more fully. "Multiple" includes "two".

[0048] Furthermore, the multiple water outlet holes 208 and the multiple first water inlet holes 101 are symmetrical about the axis of the sleeve 1, so that the overall temperature of the sleeve 1 is more balanced; the second arc groove 202 and the first arc groove 201 are symmetrical, and the first inlet hole 2041 and the first outflow hole 2051 are symmetrical, thereby making the overall temperature of the bearing seat 2 more balanced, which not only ensures that the temperature of the bearing in the bearing seat 2 is more balanced, but also avoids the bearing deformation due to the uneven overall temperature of the bearing seat 2, thereby avoiding the bearing from getting stuck and not rotating smoothly.

[0049] Furthermore, the multiple water outlet holes 208 and the multiple first water inlet holes 101 are evenly distributed along the circumference of the shaft sleeve 1 , further improving the uniform cooling of the shaft sleeve 1 .

[0050] Preferably, Figure 9-10 As shown, only one water outlet hole 208 is provided, and the water outlet hole 208 and the plurality of first water inlet holes 101 are evenly distributed along the circumference of the shaft sleeve 1; the outlet of the water outlet hole 208 is provided on the end face of the first end of the shaft sleeve 1, and a second outflow hole 2052 is provided on the bearing seat 2, the inlet of the second outflow hole 2052 is provided on the diverter surface 206, and the outlet is provided on the inlet surface 207, and the outlet of the water outlet hole 208 is connected with the inlet of the second outflow hole 2052.

[0051] One water outlet hole 208 is provided and is evenly distributed along the axial direction of the sleeve 1 together with multiple first water inlet holes 101, so that the sleeve 1 can be cooled evenly. Since only one water outlet hole 208 is provided, the flow speed of the coolant in the first water inlet hole 101 and the water outlet hole 208 is slow, which can improve the heat exchange between the coolant and the sleeve 1, so that the overall temperature of the sleeve 1 is more uniform and the working accuracy of the electric spindle is higher. The electric spindle of this scheme is suitable for places with low external ambient temperature. When the external ambient temperature is low, the heat exchange between the electric spindle and the air is large. At this time, the slower flow of the coolant can also ensure that the electric spindle is within a reasonable temperature range.

[0052] Figure 4 and Fig.10This is a schematic diagram of the coolant flow path. It is a spatial structure, not a physical structure.

[0053] Preferably, Figure 8-10 As shown, a third arc groove 203 is provided on the diverter surface 206, and the third arc groove 203 is connected to the entry surface 207 via a second entry hole 2042. A plurality of second water inlet holes 102 are also provided in the side wall of the sleeve 1, and the inlets of the plurality of second water inlet holes 102 are provided on the end surface of the first end of the sleeve 1, and the third arc groove 203 covers the plurality of third arc grooves 203.

[0054] By arranging a plurality of second water inlet holes 102 on the side wall of the sleeve 1, the plurality of water inlet holes are connected with the second water inlet hole 102 through the third arc groove 203; when injecting coolant into the sleeve 1, the coolant enters the first arc groove 201 and the third arc groove 203 through the first inlet hole 2041 and the second inlet hole 2042, and the coolant enters the first water inlet hole 101 and the second water inlet hole 102 respectively from two independent arc grooves, so that a large flow of coolant can be injected, which greatly improves the cooling speed of the sleeve 1, thereby enabling the electric spindle to rotate at a higher speed and work in a higher temperature environment.

[0055] Furthermore, the first arc groove 201 and the third arc groove 203 are symmetrically arranged about the axis of the sleeve 1, and the first water inlet hole 102 and the second water inlet hole 102 are symmetrically arranged, so that the sleeve 1 can be cooled more evenly in the circumferential direction.

[0056] Preferably, Figure 1 As shown, a first sealing member 401 is provided between the diverter surface 206 and the end surface of the first end of the shaft sleeve 1 ; and a second sealing member 402 is provided between the flange 3 and the end surface of the second end of the shaft sleeve 1 .

[0057] By setting the first sealing member 401, the first arc groove 201 set on the sleeve 1 can be sealed and connected with the first water inlet hole 101 on the sleeve 1. After the coolant enters the first arc groove 201 from the first inlet hole 2041, it will not leak from between the bearing seat 2 and the sleeve 1. Similarly, by setting the second sealing member 402, the coolant will not leak from between the sleeve 1 and the flange 3.

[0058] Preferably, Figure 1 As shown, a first bearing position 501 is provided in the bearing seat 2 , and an annular cavity 209 is provided in the bearing seat 2 . The annular cavity 209 surrounds the first bearing position 501 , and the annular cavity 209 is connected to the first entry hole 2041 via a connecting hole 210 .

[0059] By setting the annular cavity 209, the annular cavity 209 is connected with the first inlet hole 2041 through the connecting hole 210. When the coolant enters the first inlet hole 2041, part of the coolant enters the annular cavity 209. On the one hand, the coolant is closer to the bearing position and can absorb heat from the bearing on the bearing position more quickly. On the other hand, the coolant can absorb the vibration of the bearing during rotation and reduce the vibration of the shaft core 7 during rotation, which is beneficial to improving the working accuracy of the electric spindle.

[0060] For specific processing, the bearing seat 2 can be divided into two parts along the axial direction of the sleeve 1 to facilitate the processing of the annular cavity 209. After the processing of the annular cavity 209 is completed, the two parts are combined into a complete bearing seat 2, welded or bolted together, and then the first bearing position 501 is processed.

[0061] Preferably, Figure 1 As shown, the inner wall surface of the second end of the sleeve 1 is provided with a second bearing seat 502 .

[0062] The inner wall surface of the second end of the sleeve 1 is provided with a second bearing position 502 , and the first water inlet hole 101 can not only cool the sleeve 1 , but also cool the bearing on the second bearing position 502 to avoid excessive bearing temperature.

[0063] Preferably, Figure 1 As shown, when an annular groove 103 is provided, the annular groove 103 is provided on the end surface of the second end of the shaft sleeve 1 , and the depth of the annular groove 103 along the axial direction of the shaft sleeve 1 can cover a portion of the second bearing position 502 .

[0064] By making the annular groove 103 penetrate deep into the shaft sleeve 1 to a depth sufficient to cover the second bearing position 502, the coolant can more fully cool the bearing on the second bearing position 502 when entering the annular groove 103. Since the coolant surrounds part of the second bearing position 502, the coolant can absorb the vibration generated when the bearing on the second bearing position 502 rotates, which is beneficial to improving the working accuracy of the electric spindle.

[0065] The first end of the sleeve 1 is the rear end, and the bearing in the bearing seat 2 is the rear bearing 5011 . Correspondingly, the second end of the sleeve 1 is the front section, and the bearing in the second end of the sleeve 1 is the front bearing 5021 .

[0066] The invention also provides a numerically controlled machine tool, comprising the electric spindle.

[0067] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0068] 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 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 description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. An electric spindle, comprising a sleeve (1), a first end of the sleeve (1) being provided with a bearing seat (2), characterized in that: The two end surfaces of the bearing seat (2) are respectively a flow dividing surface (206) and an entrance surface (207); the flow dividing surface (206) is provided with a first arc-shaped groove (201), and the first arc-shaped groove (201) extends along the circumferential direction of the shaft sleeve (1); the bearing seat (2) is provided with a first entrance hole (2041), and the outlet of the first entrance hole (2041) leads to the first arc-shaped groove (201); A plurality of first water inlet holes (101) extending along the axial direction are arranged in the side wall of the shaft sleeve (1); the inlets of the first water inlet holes (101) are arranged on the end surface of the first end of the shaft sleeve (1); and the first arc-shaped groove (201) covers the inlets of the plurality of first inlet holes (2041).

2. The electric spindle according to claim 1, characterized in that: A water outlet hole (208) is arranged in the side wall of the shaft sleeve (1), a flange (3) is arranged at the second end of the shaft sleeve (1), an annular groove (103) is arranged between the flange (3) and the end surface of the second end of the shaft sleeve (1), and the outlet of the first water inlet hole (101) and the inlet of the water outlet hole (208) both lead to the annular groove (103).

3. The electric spindle according to claim 2, characterized in that: There are a plurality of water outlet holes (208), a second arc-shaped groove (202) is provided on the diversion surface (206), outlets of the plurality of water outlet holes (208) lead to the second arc-shaped groove (202), and the second arc-shaped groove (202) is connected to the inlet surface (207) via the first outflow hole (2051).

4. The electric spindle according to claim 2, characterized in that: Only one water outlet hole (208) is provided, and the water outlet hole (208) and the plurality of first water inlet holes (101) are evenly distributed along the circumference of the shaft sleeve (1); the outlet of the water outlet hole (208) is provided on the end surface of the first end of the shaft sleeve (1), a second outflow hole (2052) is provided on the bearing seat (2), the inlet of the second outflow hole (2052) is provided on the diversion surface (206), and the outlet is provided on the inlet surface (207), and the outlet of the water outlet hole (208) is connected to the inlet of the second outflow hole (2052).

5. The electric spindle according to claim 1, characterized in that: A third arcuate groove (203) is provided on the diverter surface (206), and the third arcuate groove (203) is connected to the inlet surface (207) via a second inlet hole (2042). A plurality of second water inlet holes (102) are also provided in the side wall of the shaft sleeve (1), and the inlets of the plurality of second water inlet holes (102) are provided on the end surface of the first end of the shaft sleeve (1), and the third arcuate groove (203) covers the plurality of third arcuate grooves (203).

6. The electric spindle according to claim 2, characterized in that: A first sealing member (401) is provided between the flow dividing surface (206) and the end surface of the first end of the shaft sleeve (1); and a second sealing member (402) is provided between the flange (3) and the end surface of the second end of the shaft sleeve (1).

7. The electric spindle according to claim 1, characterized in that: A first bearing position (501) is arranged in the bearing seat (2), and an annular cavity (209) is arranged in the bearing seat (2). The annular cavity (209) surrounds the first bearing position (501), and the annular cavity (209) is connected to the first entry hole (2041) via a connecting hole (210).

8. The electric spindle according to any one of claims 1 to 7, characterized in that: The inner wall surface of the second end of the shaft sleeve (1) is provided with a second bearing seat (502).

9. The electric spindle according to claim 8, characterized in that: When an annular groove (103) is provided, the annular groove (103) is provided on the end surface of the second end of the shaft sleeve (1), and the depth of the annular groove (103) along the axial direction of the shaft sleeve (1) can cover part of the second bearing position (502).

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

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