Electrical spindle, machine tool

Abstract

The utility model provides a kind of electric spindle, machine tool, wherein electric spindle, including shaft core and the shell that is sleeved in its radial outside, annular space between shaft core and shell is equipped with driving motor, driving motor includes motor stator and motor rotor, the stator core of motor stator is connected on the inner ring wall of shell, motor rotor is on the outer circular wall of shaft core, shaft core is supported in shell via front end bearing and rear end bearing, first cooling flow channel is formed in shell, first cooling flow channel has the part in the radial outside of stator core, annular cooling cavity is also equipped on the inner ring wall of shell, annular cooling cavity surrounds with shaft core setting, and annular cooling cavity is between front end bearing and motor rotor.The utility model realizes the overall cooling heat dissipation of inside and outside double layers of electric spindle, effectively improves the cooling heat dissipation effect of electric spindle, annular cooling cavity can reduce the conduction of friction heat generated when front end cutter of shaft core is in machining operation along shaft core to its rear end.

Description

Technical Field

[0001] This utility model belongs to the field of machine tool design technology, specifically relating to an electric spindle and a machine tool. Background Technology

[0002] An electric spindle is a new technology that integrates the machine tool spindle and spindle motor into one unit. The spindle is directly driven by the built-in motor, eliminating the gear, belt, or coupling transmission of traditional spindles, thus shortening the transmission chain length of the machine tool spindle to zero. It is widely used in the manufacturing of precision molds, automobiles, ships, aerospace, and other cutting-edge products. The electric spindle has a complex structure, with the spindle core being the core component. Bearings, motors, and other parts are assembled on it, and the overall assembly precision determines the rotational accuracy of the electric spindle.

[0003] Existing high-speed electric spindles supported by sliding bearings primarily rely on external spiral cooling water jackets installed on the motor stator to circulate coolant and cool the stator and spindle housing. This external cooling structure is simplistic and insufficient to remove internal heat. The main heat sources of the motor include stator core heating, winding copper loss heating, and rotor iron loss heating, accounting for approximately 60% of the total heat generated by the electric spindle. However, the stator windings and rotor, which currently account for more than two-thirds of the motor's heat generation, are not effectively cooled. Simultaneously, the heat source of the sliding bearings mainly originates from the viscous shear friction of the high-speed fluid in the bearing clearance, generating approximately 30% of the total spindle heat. Part of this heat is transferred to the outside through the bearing bushes, part to the spindle core through the journals, and some is transferred through fluid convection, increasing the spindle core temperature rise. Furthermore, during prolonged continuous machining, high-speed friction in the machining zone raises the cutting temperature, and heat from the cutting tool is also transferred to the spindle core, further increasing its temperature. Current electric spindle cooling methods or structures are too simplistic and cannot effectively cool the electric spindle. This results in severe temperature rise and thermal deformation of the spindle core, making it difficult to guarantee the machining accuracy of the spindle at high speeds and leading to a shorter service life for the electric spindle. Utility Model Content

[0004] Therefore, this utility model provides an electric spindle and machine tool that can overcome the shortcomings of the related technologies, such as the overly simple cooling methods or structures of electric spindles, which cannot effectively cool the electric spindle, causing severe temperature rise and thermal deformation of the spindle core, making it difficult to guarantee the machining accuracy of the electric spindle, and resulting in a short service life of the electric spindle.

[0005] To address the aforementioned problems, this utility model provides an electric spindle, comprising a spindle core and a housing fitted radially outward from the spindle core. A drive motor is disposed within the annular space between the spindle core and the housing. The drive motor includes a motor stator and a motor rotor. The stator core of the motor stator is connected to the inner annular wall of the housing, and the motor rotor is located on the outer circular wall of the spindle core. The spindle core is supported within the housing via a front bearing and a rear bearing. A first cooling channel is formed within the housing, with a portion located radially outward from the stator core. An annular cooling cavity is also provided on the inner annular wall of the housing, surrounding the spindle core and positioned between the front bearing and the motor rotor.

[0006] In some embodiments, the first cooling channel is a double-helix cross structure; and / or, the housing includes a cooling sleeve and an outer sleeve fitted onto the outer circular wall of the cooling sleeve, the first cooling channel is formed on the outer circular wall of the cooling sleeve, the stator core is assembled on the inner ring wall of the cooling sleeve, and the annular cooling cavity is formed on the inner ring wall of the cooling sleeve.

[0007] In some embodiments, the annular cooling cavity has at least one spacer ring extending radially toward the shaft core, the spacer ring dividing the annular cooling cavity into a plurality of cooling sub-cavities spaced axially along the shaft core, and an annular flow gap forming between the spacer ring and the shaft core between two adjacent cooling sub-cavities.

[0008] In some embodiments, annular grooves are formed on the inner surface of each of the spacer rings.

[0009] In some embodiments, both the front bearing and the rear bearing are sliding bearings, the front bearing has a first bearing cooling structure that communicates with the first cooling channel, and the rear bearing has a second bearing cooling structure that communicates with the first cooling channel.

[0010] In some embodiments, the front bearing is a radial bearing, and the first bearing cooling structure includes a plurality of first cooling ring grooves arranged sequentially at intervals from the central region of the length of the front bearing to the regions on both sides of the length, each of the first cooling ring grooves surrounding the shaft core and the groove opening of each of the first cooling ring grooves facing one side of the shaft core.

[0011] In some embodiments, the inlet and outlet of the first bearing cooling structure are on the same first radial plane of the shaft core, each of the first cooling ring grooves is located on opposite sides of the first radial plane, and the volume of each of the first cooling ring grooves increases along the direction away from the first radial plane, and / or, each of the first cooling ring grooves is symmetrically arranged about the first radial plane.

[0012] In some embodiments, the rear bearing is a radial bearing, and the second bearing cooling structure includes a second cooling ring groove, which is arranged around the shaft core with the groove opening facing the shaft core.

[0013] In some embodiments, an adjusting ring and a bearing cover are provided on the end face of the rear bearing away from the motor rotor. The adjusting ring is clamped between the bearing cover and the rear bearing to form an annular positioning space between the rear bearing and the bearing cover. A thrust disk is fitted on the shaft core and is located within the annular positioning space. The second bearing cooling structure further includes a first branch cooling channel formed in the rear bearing and communicating with the annular positioning space and / or a second branch cooling channel communicating with the annular positioning space in sequence via the rear bearing, the adjusting ring and the bearing cover.

[0014] In some embodiments, the cooling medium flowing in the first cooling channel and the annular cooling cavity is cooling water. A first sealing ring is provided between the inner annular wall of the housing and the shaft core, and a second sealing ring is provided between the rear bearing and the shaft core. A sealed accommodating space is formed between the first sealing ring and the second sealing ring. The drive motor is assembled in the sealed accommodating space, and the sealed accommodating space is controllably connected to the pressurized gas. The pressurized gas entering the sealed accommodating space 100 can enter the annular cooling cavity through the first sealing ring and / or enter the second cooling ring groove through the second sealing ring.

[0015] In some embodiments, both the first sealing ring and the second sealing ring are unidirectional flexible sealing rings, wherein the unidirectional flow direction of the first sealing ring is from the motor rotor to the annular cooling cavity, and the unidirectional flow direction of the second sealing ring is from the motor rotor to the rear bearing.

[0016] In some embodiments, the second sealing ring is assembled on the rear bearing, the rear bearing having a first airflow annular groove, the first airflow annular groove and the second cooling annular groove being located on opposite sides of the second sealing ring, the first airflow annular groove being located near the motor rotor of the second sealing ring, and the groove opening of the first airflow annular groove facing the shaft core side; and / or, the flexible sealing ring has a mounting ring and a deformation ring extending on the inner ring wall of the mounting ring and facing the shaft core side, and the deformation ring is inclined towards its unidirectional flow direction side.

[0017] In some embodiments, the rear bearing is provided with a pressure-uniformity annular cavity, which is concentrically arranged with the first airflow annular groove and connected through a plurality of vent holes. Each of the vent holes is evenly spaced along the circumferential direction of the first airflow annular groove, and the pressurized gas is controllably connected to the pressure-uniformity annular cavity.

[0018] In some embodiments, a second airflow annular groove is further formed within the front bearing. The second airflow annular groove surrounds the shaft core and is located on the side of each of the first cooling annular grooves near the annular cooling cavity. A third sealing ring and a fourth sealing ring are respectively provided on both sides of the length of the shaft core. The third sealing ring is located between the second airflow annular groove and the first cooling annular groove, and the fourth sealing ring is located between the second airflow annular groove and the annular cooling cavity. Both the third and fourth sealing rings are unidirectional flexible sealing rings. The unidirectional flow direction of the third sealing ring is from the second airflow annular groove to the first cooling annular groove, and the unidirectional flow direction of the fourth sealing ring is from the second airflow annular groove to the annular cooling cavity.

[0019] In some embodiments, a sealed third airflow annular groove is formed between the radially outer side of the front bearing and the inner annular wall of the housing, and the third airflow annular groove communicates with the second airflow annular groove.

[0020] In some embodiments, an exhaust channel is formed within the housing, and the exhaust channel is connected to the third airflow annular groove; and / or, an inlet channel is formed within the housing, and the inlet of the sealed accommodating space and the second airflow annular groove is controllably connected to the inlet channel.

[0021] In some embodiments, a cooling medium inlet channel and a cooling medium outlet channel are formed within the housing, and the first cooling channel, the annular cooling cavity, the first bearing cooling structure, and the second bearing cooling structure are simultaneously connected in parallel between the cooling medium inlet channel and the cooling medium outlet channel.

[0022] In some embodiments, a self-lubricating sealing ring is provided between the front bearing and the shaft core.

[0023] In some embodiments, the front bearing is provided with a first temperature sensor for detecting its real-time temperature; and / or, the housing is further provided with a second temperature sensor for detecting the real-time temperature of the stator core.

[0024] This utility model also provides a machine tool, including the above-mentioned electric spindle.

[0025] The electric spindle and machine tool provided by this utility model have the following beneficial effects: The electric spindle is equipped with both a first cooling channel and an annular cooling cavity. The first cooling channel provides efficient cooling to the radially outer region of the stator core, while the annular cooling cavity provides efficient cooling to the spindle core. This achieves comprehensive cooling of both the inner and outer layers of the electric spindle, effectively improving the cooling effect. More importantly, the annular cooling cavity is located between the front bearing and the motor rotor, enabling efficient cooling of both the spindle core and the front bearing simultaneously. It also effectively reduces the conduction of frictional heat generated by the cutting tool at the front of the spindle during machining (e.g., cutting) along the spindle core to its rear end, further reducing the overall temperature rise of the electric spindle. This, in turn, reduces thermal deformation of components such as the spindle core, improving the machining accuracy and service life of the electric spindle. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. The drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the internal structure of the electric spindle in an embodiment of the present invention (on a axial section), and the arrows in the figure indicate the flow direction of the cooling medium; Figure 2 yes Figure 1 A magnified view of a section at point A in the middle; Figure 3 yes Figure 1 A magnified view of section B in the image; Figure 4 This is a schematic diagram of the internal structure of the electric spindle in an embodiment of the present invention (on another axial section), and the arrows in the figure indicate the flow direction of the pressurized airflow; Figure 5 yes Figure 1 A schematic diagram of the front bearing (axial section); Figure 6 yes Figure 1A schematic diagram of the rear bearing structure (axial section).

[0028] The attached figures are labeled as follows: 1. Shaft core; 11. Thrust disc; 21. Motor stator; 22. Motor rotor; 3. Front bearing; 31. First cooling ring groove; 32. Second airflow ring groove; 33. Third airflow ring groove; 4. Rear bearing; 41. Second cooling ring groove; 42. Adjusting ring; 43. Bearing cover; 441. First branch cooling channel; 442. Second branch cooling channel; 451. First airflow ring groove; 452. Air pressure equalization ring cavity; 453. Vent hole; 51. First cooling channel; 52. Annular cooling cavity; 521. Spacer ring; 522, Annular groove; 531, Cooling sleeve; 532, Outer sleeve; 533, Front end cover; 534, Rear end cover; 541, Cooling medium inlet channel; 542, Cooling medium outlet channel; 551, Exhaust channel; 552, Inlet channel; 61, First sealing ring; 62, Second sealing ring; 63, Third sealing ring; 64, Fourth sealing ring; 71, Self-lubricating sealing ring; 72, Labyrinth seal assembly; 81, First temperature sensor mounting cavity; 82, Second temperature sensor mounting cavity; 100, Sealed accommodating space. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0030] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0031] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0032] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0033] See also Figures 1 to 6 As shown, according to an embodiment of the present invention, an electric spindle is provided, including a spindle core 1 and a housing (not indicated in the figure) fitted on the radially outer side of the spindle core 1. A drive motor (not indicated in the figure) is provided in the annular space (not indicated in the figure) between the spindle core 1 and the housing. The drive motor is used to drive the spindle core 1 to rotate. The drive motor includes a motor stator 21 and a motor rotor 22. The stator core (not indicated in the figure) of the motor stator 21 is connected (generally by interference fit) to the inner annular wall of the housing. The motor rotor 22 is located on the outer circular wall of the spindle core 1 (generally by interference fit). The shaft core 1 is fitted onto the shaft core 1. The shaft core 1 is supported in the housing by a front bearing 3 and a rear bearing 4. The front bearing 3 is the bearing at the end of the shaft core 1 that corresponds to the end where the tool is connected, and the rear bearing 4 is the bearing at the other end of the shaft core 1. A first cooling channel 51 is formed in the housing. The first cooling channel 51 has a portion located on the radial outer side of the stator core. An annular cooling cavity 52 is also provided on the inner ring wall of the housing. The annular cooling cavity 52 is arranged around the shaft core 1 and is located between the front bearing 3 and the motor rotor 22.

[0034] In this technical solution, a first cooling channel 51 and an annular cooling cavity 52 are simultaneously provided inside the electric spindle. The first cooling channel 51 can form efficient cooling and heat dissipation for the radially outer region of the stator core, while the annular cooling cavity 52 can form efficient cooling and heat dissipation for the spindle core 1. This achieves comprehensive cooling and heat dissipation for both the inner and outer layers of the electric spindle, effectively improving the cooling and heat dissipation effect of the electric spindle. More importantly, the annular cooling cavity 52 is located between the front bearing 3 and the motor rotor 22, thus achieving efficient cooling and heat dissipation for both the spindle core 1 and the front bearing 3. At the same time, it can also effectively reduce the conduction of frictional heat generated by the front tool of the spindle core 1 during machining (such as cutting) along the spindle core 1 to its rear end, further reducing the overall temperature rise of the electric spindle, thereby reducing the thermal deformation of components such as the spindle core 1, and improving the machining accuracy and service life of the electric spindle.

[0035] In some embodiments, the first cooling channel 51 is a double-helix cross structure. That is, objectively, the first cooling channel 51 is specifically two spiral channels that intersect each other. The two intersecting spiral channels will form a mesh-like cooling channel. The mesh structure provides a large heat exchange area. When the cooling medium flows through the connection point of the mesh structure, the cooling medium is continuously divided and merged and the flow direction changes, generating extremely strong eddies and turbulence, thereby maximizing the heat exchange efficiency.

[0036] It should be noted that the aforementioned first cooling channel 51 preferably covers the entire axial and circumferential directions of the housing, so that the cooling medium can flow across the entire surface of the housing as much as possible, so as to quickly and evenly remove the heat from the housing and control the thermal deformation of the electric spindle to a minimum.

[0037] In one specific embodiment, the housing includes a cooling sleeve 531 and an outer sleeve 532 fitted onto the outer circular wall of the cooling sleeve 531. In this case, the first cooling channel 51 is formed on the outer circular wall of the cooling sleeve 531. Specifically, the first cooling channel 51 is formed on the outer circular wall of the cooling sleeve 531 in the form of a spiral opening groove, simplifying the manufacturing process. The stator core is assembled on the inner annular wall of the cooling sleeve 531, and the annular cooling cavity 52 is formed on the inner annular wall of the cooling sleeve 531. It is understood that... (See also...) Figure 1 As shown, the aforementioned housing also includes a front end cap 533 and a rear end cap 534 that are sealed at the front and rear ends of the aforementioned outer sleeve 532.

[0038] In some embodiments, the annular cooling cavity 52 has at least one spacer ring 521 extending radially toward the shaft core 1, the spacer ring 521 dividing the annular cooling cavity 52 into a plurality of cooling sub-cavities (not shown in the figure) spaced axially along the shaft core 1. See also Figure 1As shown, in a specific embodiment, two spacer rings 521 are specifically provided. The two spacer rings 521 divide the annular cooling cavity 52 into three interconnected cooling sub-cavities along the axial direction of the shaft core 1. An annular flow gap is formed between the spacer rings 521 and the shaft core 1 between adjacent cooling sub-cavities. The aforementioned annular flow gap should generally not be too large, with the basic principle being to avoid radial collision with the shaft core 1. It can be understood that the radial gap between the aforementioned spacer rings 521 and the shaft core 1 is much smaller than the cavity diameter of the annular cooling cavity 52.

[0039] In this technical solution, multiple spacer rings 521 are arranged axially along the shaft core 1 within the annular cooling cavity 52, thereby dividing the large-volume annular cooling cavity 52 into multiple cooling sub-cavities connected by smaller annular flow gaps. This increases the fluid resistance of the cooling medium within the annular cooling cavity 52, making it easier for the cooling medium fluid to form turbulence, thus enabling the cooling medium to carry away more heat and improve the cooling and heat dissipation effect at that location. At the same time, the increased fluid resistance also helps to increase the fluid pressure of the cooling medium fluid within the annular cooling cavity 52, thereby ensuring stable support for the shaft core 1 corresponding to that area and reducing the risk of shaft core 1 instability caused by using annular cooling cavities 52 with larger axial spacing.

[0040] In some embodiments, annular grooves 522 are formed on the inner annular surface of each spacer ring 521. In some embodiments, there are multiple annular grooves 522, and each annular groove 522 is spaced apart on the inner annular surface of each spacer ring 521 in the axial direction of the shaft core 1.

[0041] In this technical solution, annular grooves 522 are further provided on the inner ring surface of each spacer ring 521 to store part of the cooling medium. This can increase the amount of cooling medium fluid stored in the annular flow gap between the shaft core 1 and the spacer ring 521, improve the compressive strength of the cooling medium in the annular flow gap, reduce the risk of contact and collision between the shaft core 1 and the spacer ring 521, and objectively improve the support stiffness of the housing for the shaft core 1.

[0042] Specifically, see Figure 2As shown, each spacer ring 521 divides the aforementioned annular cooling chamber 52 into multiple axially spaced cooling sub-chambers. Furthermore, multiple annular grooves 522 are further provided on each spacer ring 521, thus forming alternating large-volume and small-volume liquid storage areas along the axial direction of the shaft core 1. When cooling (lubricating) water is used as the cooling fluid, the larger-volume liquid storage areas can also be called large water tanks (also known as macroscopic water storage areas). Their main function is to store and distribute the cooling and lubricating medium (water) and serve as the macroscopic starting point for the hydrodynamic effect. Their large volume ensures sufficient water supply. The water is carried into the bearing clearance, which also helps to distribute the water flow evenly across the entire bearing surface, enhancing the heat exchange and cooling effect. The smaller liquid storage area can also be called a small annular groove (also known as a micro dynamic pressure generator). Its main function is to generate fluid dynamic pressure accurately and at high frequency. They are numerous and small in size, which can divide a large water film into a series of smaller and more controllable dynamic pressure regions. When the spindle rotates, water is continuously carried from one large groove into multiple subsequent small grooves. A local pressure peak can be generated in the inlet area (converging wedge region) of each small groove, thereby improving the support stiffness.

[0043] The axially spaced cooling sub-cavities and annular grooves 522 on the shaft core 1 will have the following significant advantages: (1) Multi-stage pressure boosting effect: When the spindle rotates, the fluid passes through the "large groove -> small groove -> large groove" cycle in sequence. In the transition area between each "large groove to the first small groove" and "the previous small groove to the next small groove", a convergence gap will be formed, thereby generating fluid dynamic pressure. This design is equivalent to setting up a multi-stage "dynamic pressure pump", which connects and superimposes the overall dynamic pressure effect, and can generate higher and more stable fluid dynamic pressure than a single groove type, thereby significantly improving the bearing capacity.

[0044] (2) Continuous and uniform lubricating water film and cooling effect: The presence of multiple small grooves ensures that the lubricating film can be frequently "refreshed" and "rebuilt" on the entire bearing contact surface. This avoids the risk of the lubricating film becoming thin or breaking in groove-free areas, ensuring the continuity and reliability of lubrication; the large water tank, as the main heat storage unit, holds the water heated by friction between the spindle and other parts, while the dense small groove structure greatly increases the contact area (heat exchange area) between the water and the cooling water jacket, and the flow rate and turbulence of the water increase when it flows through these small grooves, which greatly enhances the heat exchange process and enhances the cooling effect of the electric spindle; (3) Strong adaptability to changes in working conditions: Under low and medium speed and heavy load conditions, the large water tank can ensure that enough lubricating water is brought into the spindle to provide basic lubrication and cooling; under high speed conditions, the dynamic pressure effect of the small ring groove is fully utilized to provide the main load capacity. Therefore, this design can maintain good performance in a wide range of speeds and loads.

[0045] In some embodiments, both the front bearing 3 and the rear bearing 4 are sliding bearings. The front bearing 3 has a first bearing cooling structure that communicates with the first cooling channel 51, and the rear bearing 4 has a second bearing cooling structure that communicates with the first cooling channel 51. In this case, it can be understood that the aforementioned cooling medium fluid serves as the flow medium for the aforementioned first bearing cooling structure and the second bearing cooling structure, and also as the fluid film medium for the aforementioned sliding bearing. For example, when the cooling medium fluid is liquid, a liquid film is formed, and when the cooling medium is gas, a gas film is formed. The sliding bearing has less friction and a certain vibration damping capability.

[0046] In this technical solution, by setting corresponding bearing cooling structures connected to the first cooling channel 51 in the front bearing 3 and the rear bearing 4 respectively, the temperature rise of the front bearing 3 and the rear bearing 4 can be further reduced, achieving more comprehensive cooling of the electric spindle and further reducing the overall temperature rise of the electric spindle. At this time, when the film layer of the sliding bearing is a liquid film, such as lubricating oil or water, the reduction of the temperature rise of the electric spindle can also prevent the viscosity of oil or water from decreasing due to excessive temperature rise, which is beneficial to improving the bearing capacity and rigidity of the sliding bearing on the shaft core 1.

[0047] In some embodiments, the front bearing 3 is a radial bearing, and the first bearing cooling structure includes regions extending from the central region of the length of the front bearing 3 to both sides of its length (i.e., Figure 5 Multiple first cooling ring grooves 31 are arranged at intervals from the middle to both ends in the indicated orientation. Each first cooling ring groove 31 surrounds the shaft core 1, and the groove opening of each first cooling ring groove 31 faces one side of the shaft core 1, thereby achieving efficient cooling of the front bearing 3.

[0048] In some embodiments, the inlet (not labeled) and outlet (not labeled) of the first bearing cooling structure are on the same first radial plane (not labeled) of the shaft core 1. Each of the first cooling ring grooves 31 is located on opposite sides of the first radial plane, and the volume of each first cooling ring groove 31 increases along the direction away from the first radial plane. This increases the flow area of ​​the cooling medium in each first cooling ring groove 31, reducing the flow resistance (i.e., pressure drop) of the cooling medium in the later stages. Under the premise of the same fluid pumping power, a larger cooling medium flow rate can be obtained, ensuring heat exchange efficiency and improving the overall heat dissipation capacity. In a specific embodiment, each of the first cooling ring grooves 31 is symmetrically arranged about the first radial plane, which can eliminate gradient temperature difference, suppress thermal deformation to the maximum extent, and ensure high radial and axial accuracy of the electric spindle under long-term operation.

[0049] In some embodiments, the rear bearing 4 is a radial bearing, and the second bearing cooling structure includes a second cooling ring groove 41. The second cooling ring groove 41 is arranged around the shaft core 1 and the groove opening of the second cooling ring groove 41 faces the shaft core 1. The arrangement of the second cooling ring groove 41 around the shaft core 1 in the rear bearing 4 can achieve efficient cooling of the rear bearing 4 while forming a sliding bearing film.

[0050] In some embodiments, the rear bearing 4 has an adjusting ring 42 (in a specific embodiment, an elastic adjusting ring) and a bearing cover 43 on the end face away from the motor rotor 22. The adjusting ring 42 is clamped between the bearing cover 43 and the rear bearing 4 to form an annular positioning space between the rear bearing 4 and the bearing cover 43. A thrust disk 11 is fitted on the shaft core 1, and the thrust disk 11 is located within the annular positioning space. This achieves the integration of axial support function for the shaft core 1 on the radial bearing. The rear bearing 4 has both radial and axial support functions, has a compact structure, and reduces improper occupation of the shaft length of the shaft core 1. The second bearing cooling structure also includes a first branch cooling channel 441 formed in the rear bearing 4 and communicating with the annular positioning space and / or a second branch cooling channel 442 communicating with the annular positioning space via the rear bearing 4, the adjusting ring 42 and the bearing cover 43 in sequence. The aforementioned first branch cooling channel 441 and second branch cooling channel 442 can achieve all-round cooling of the rear bearing 4.

[0051] In some embodiments, the cooling medium flowing through the first cooling channel 51 and the annular cooling cavity 52 is cooling water. A first sealing ring 61 is provided between the inner annular wall of the housing and the shaft core 1, and a second sealing ring 62 is provided between the rear bearing 4 and the shaft core 1. A sealed accommodating space 100 is formed between the first sealing ring 61 and the second sealing ring 62. The drive motor is assembled within the sealed accommodating space 100. This prevents the aforementioned cooling water from entering the sealed accommodating space 100, ensuring the normal operation of the drive motor. The sealed accommodating space 100 is controllably connected to pressurized gas, and the pressurized gas entering the sealed accommodating space 100 can enter the annular cooling cavity 52 via the first sealing ring 61 and / or enter the second cooling ring groove 41 via the second sealing ring 62. The aforementioned pressurized gas can be generated, for example, by an air pump externally mounted on the electric spindle. Specifically, the aforementioned pressurized gas can be filtered air.

[0052] In this technical solution, pressurized gas is introduced into the sealed accommodating space 100 where the drive motor is located. The pressurized gas can enter the annular cooling chamber 52 and the second cooling ring groove 41 through the first sealing ring 61 and the second sealing ring 62, forming a flow of pressurized gas. On the one hand, it can carry the heat inside the drive motor to the cooling medium fluid, and further transfer it with the cooling medium fluid to the heat dissipation components outside the electric spindle (such as water chiller, air-cooled radiator, etc.) for efficient dissipation, further reducing the temperature rise of the electric spindle. On the other hand, the pressurized gas enters the cooling medium fluid and forms a mixture, increasing the turbulence of the cooling medium and improving the heat exchange effect of the cooling medium fluid.

[0053] In some embodiments, both the first sealing ring 61 and the second sealing ring 62 are unidirectional flexible sealing rings. Specifically, the unidirectional flow direction of the first sealing ring 61 is from the motor rotor 22 to the annular cooling cavity 52, and the unidirectional flow direction of the second sealing ring 62 is from the motor rotor 22 to the rear bearing 4. See details... Figure 1 As shown, the flexible sealing ring has an installation ring (not labeled in the figure) and a deformation ring (not labeled in the figure) located on the inner ring wall of the installation ring and extending toward the shaft core 1, and the deformation ring is inclined toward its unidirectional flow direction.

[0054] In this technical solution, the deformation ring of the flexible sealing ring is tilted towards its unidirectional flow direction. This effectively prevents the cooling medium fluid from leaking into the assembly space of the drive motor, i.e., the aforementioned sealed accommodating space 100. At the same time, it can easily be biased and deformed towards its unidirectional flow direction under the action of pressurized gas, thereby allowing the pressurized gas to enter the cooling medium fluid. This process achieves unidirectional gas sealing of the flexible sealing ring. At the same time, due to the unidirectional flow of pressurized gas in the annular gap between the flexible sealing ring and the shaft core 1, the flexible sealing ring and the shaft core 1 are also disengaged, effectively reducing frictional heat generation and wear between the shaft core 1 and the sealing ring, and improving the service life of the flexible sealing ring.

[0055] In some embodiments, the second sealing ring 62 is assembled on the rear bearing 4, and the rear bearing 4 is provided with a first airflow annular groove 451. The first airflow annular groove 451 and the second cooling annular groove 41 are respectively located on both sides of the second sealing ring 62. The first airflow annular groove 451 is located on the second sealing ring 62 near the motor rotor 22, and the groove opening of the first airflow annular groove 451 faces the shaft core 1.

[0056] In this technical solution, the rear bearing 4 has a first airflow ring groove 451, a second cooling ring groove 41, and a second sealing ring 62, which can significantly simplify the number of parts, reduce the installation difficulty, eliminate the influence of installation errors on the sealing effect, and improve the performance and service life of the bearing and electric spindle under high-speed operation.

[0057] In some embodiments, the rear bearing 4 is provided with a pressure equalization annular cavity 452. The pressure equalization annular cavity 452 is concentrically arranged with the first airflow annular groove 451 and communicates with it through a plurality of vent holes 453. Each of the vent holes 453 is evenly spaced along the circumferential direction of the first airflow annular groove 451. The pressurized gas is controllably connected to the pressure equalization annular cavity 452, so that the pressure of the pressurized gas entering the first airflow annular groove 451 is more even in the circumferential direction of the shaft core 1, ensuring reliable unidirectional flow control of the flexible sealing ring.

[0058] In some embodiments, a second airflow annular groove 32 is also formed within the front bearing 3. The second airflow annular groove 32 is arranged around the shaft core 1 and is located on the side of each of the first cooling annular grooves 31 near the annular cooling cavity 52. ​​A third sealing ring 63 and a fourth sealing ring 64 are respectively provided on both sides of the length of the shaft core 1. The third sealing ring 63 is located between the second airflow annular groove 32 and the first cooling annular groove 31, and the fourth sealing ring 64 is located between the second airflow annular groove 32 and the annular cooling cavity 52. ​​Both the third sealing ring 63 and the fourth sealing ring 64 are unidirectional flexible sealing rings. The unidirectional flow direction of the third sealing ring 63 is from the second airflow annular groove 32 to the first cooling annular groove 31, and the unidirectional flow direction of the fourth sealing ring 64 is from the second airflow annular groove 32 to the annular cooling cavity 52.

[0059] In this technical solution, on the one hand, by introducing pressurized gas into the second airflow annular groove 32, some of the heat from the front bearing 3 can be carried into the first cooling annular groove 31 and the annular cooling chamber 52 via the third sealing ring 63 and the fourth sealing ring 64, thereby improving the efficient cooling of the front bearing 3. On the other hand, the pressurized gas entering the cooling medium fluid forms turbulence, which can promote the cooling effect of the cooling medium fluid.

[0060] It should be noted that, in order to reduce the cavitation and noise of the water pump (when the cooling medium is cooling water) caused by the pressurized gas entering the cooling medium fluid circulation, a corresponding vent valve should be installed on the pipeline before the cooling medium fluid enters the water pump to allow the pressurized gas carried in the cooling medium circulation to be discharged in a timely manner. Ideally, the aforementioned vent valve should be installed on the pipeline between the cooling medium fluid flowing out from the electric spindle and the heat exchanger (for example, it can be a component of the chiller unit), thereby improving the heat exchange efficiency of the cooling medium in the heat exchanger.

[0061] In some embodiments, a sealed third airflow annular groove 33 is formed between the radially outer side of the front bearing 3 and the inner annular wall of the housing, and the third airflow annular groove 33 is connected to the second airflow annular groove 32.

[0062] In this technical solution, a third airflow annular groove 33 is further provided around the radial outer side of the front bearing 3, and the third airflow annular groove 33 is connected to the second airflow annular groove 32. That is, pressurized gas can enter the third airflow annular groove 33 and form air cooling on the front bearing 3 from the radial outer side of the front bearing 3, further reducing the temperature rise and deformation of the front bearing 3 caused by frictional heat generated during tool cutting and other operations, and further improving the running accuracy of the electric spindle.

[0063] In some embodiments, an exhaust channel 551 is formed inside the housing. The exhaust channel 551 is connected to the third airflow annular groove 33 and to the external environment of the electric spindle. The pressurized gas entering the third airflow annular groove 33 can be further vented through the exhaust channel 551. In this way, the heat of the front bearing 3 can be carried by the pressurized gas and discharged to the outside of the electric spindle, further reducing the temperature rise and deformation of the front bearing 3.

[0064] In some embodiments, an air intake channel 552 is formed inside the housing, and the inlet of the sealed accommodating space 100 and the second airflow annular groove 32 is controllably connected to the air intake channel 552, making the design of the airflow channel more reasonable and the electric spindle structure more compact.

[0065] In some embodiments, a cooling medium inlet channel 541 and a cooling medium outlet channel 542 are formed within the housing. The first cooling channel 51, the annular cooling chamber 52, the first bearing cooling structure, and the second bearing cooling structure are simultaneously connected in parallel between the cooling medium inlet channel 541 and the cooling medium outlet channel 542. Specifically, the aforementioned cooling medium inlet channel 541 is controllably connected to the pump outlet of a water pump (not shown in the figure, not labeled), and the aforementioned cooling medium outlet channel 542 is controllably connected to the pump inlet of the water pump through a corresponding external cooling structure (such as a chiller or heat exchanger), thereby utilizing the pumping action of the water pump to achieve a closed-loop circulation of the cooling medium fluid (such as cooling water).

[0066] In some embodiments, a self-lubricating sealing ring 71 is provided between the front bearing 3 and the spindle core 1 to reliably seal the head of the spindle core 1, preventing lubricating water (i.e., cooling water) from leaking out and external impurities from entering the electric spindle. At the same time, the aforementioned self-lubricating sealing ring 71 can also buffer the spindle core 1 and prevent the offset from continuing to increase when the electric spindle causes radial displacement due to accidents (such as excessive machine tool vibration, sudden interruption of cooling water, etc.), thereby ensuring machining accuracy.

[0067] In some embodiments, a labyrinth seal assembly 72 is provided between the bearing cap 43 and the shaft core 1 to achieve a reliable seal on the tail end of the shaft core 1 and prevent the cooling medium fluid from leaking from the tail end of the shaft core 1.

[0068] In some embodiments, the front bearing 3 is provided with a first temperature sensor (not shown in the figure) for detecting its real-time temperature. Specifically, a corresponding first temperature sensor mounting cavity 81 is formed on one end face of the front bearing 3, and the aforementioned first temperature sensor is assembled in the first temperature sensor mounting cavity 81. And / or, the housing is also provided with a second temperature sensor (not shown in the figure) for detecting the real-time temperature of the stator core. Specifically, a corresponding second temperature sensor mounting cavity 82 is provided on the end face of the cooling sleeve 531 near the stator core, and the aforementioned second temperature sensor is assembled in the second temperature sensor mounting cavity 82. By setting the first temperature sensor and the second temperature sensor to detect the real-time temperature of the front bearing 3 and the stator core, the speed of the corresponding water pump and air pump can be adjusted in a timely manner according to the real-time temperature, thereby adjusting the flow rate of the cooling medium fluid and the pressurized gas, ensuring a highly efficient cooling effect on the electric spindle.

[0069] The flow direction of the cooling medium fluid (such as cooling water, also known as lubricating water) and the pressurized gas in this utility model is further explained below with reference to the corresponding accompanying drawings: like Figure 1As shown, pressurized lubricating water (i.e., the aforementioned cooling medium fluid) enters the water channels of the front radial bearing (i.e., the aforementioned front end bearing 3), the cooling water jacket (i.e., the aforementioned housing), and the rear radial bearing (i.e., the aforementioned rear end bearing 4) through the water supply channel (i.e., the aforementioned cooling medium inlet channel 541). The lubricating water reaching the front radial bearing flows through the gap between the front radial bearing and the main shaft (i.e., the aforementioned shaft core 1) into the front and rear symmetrical annular return water grooves (i.e., the aforementioned first cooling ring groove 31) of the front radial bearing, and then flows out through the drainage channel (i.e., the aforementioned cooling medium outlet channel 542) to form a lubricating water circuit. The lubricating water reaching the cooling water jacket is divided into two paths, an outer path and an inner path. The outer path directly enters the double spiral mesh cross annular groove of the cooling water jacket (i.e., the inner path). The aforementioned first cooling channel 51 flows out through the drainage channel, while the internal water channel reaches the middle of the main shaft, passes through the internal return water groove (i.e., the aforementioned annular cooling chamber 52), and then flows into the drainage channel. The lubricating water reaching the rear radial bearing is also divided into two paths: one path passes through the rear radial bearing, the adjusting ring (i.e., the aforementioned adjusting ring 42), and the rear bearing cover (i.e., the aforementioned bearing cover 43) to the gap between the thrust bearing (i.e., the aforementioned thrust disc 11) and the rear bearing cover, and then flows out through the middle annular return water groove of the rear radial bearing and the rear annular return water groove of the rear bearing (i.e., the second cooling ring groove 41) into the drainage channel; the other path directly enters the rear radial bearing, passes through the gap between the rear radial bearing and the main shaft, enters the front annular return water groove of the rear radial bearing, and then flows out through the drainage channel.

[0070] like Figure 2 As shown, compressed air (i.e., the aforementioned pressurized gas) enters the air passages (i.e., the aforementioned second airflow annular groove 32 and the aforementioned first airflow annular groove 451) of the front radial bearing and the rear radial bearing respectively through the main air supply passage (i.e., the aforementioned air intake passage 552). After entering the front radial bearing air supply passage in the front radial bearing, the compressed air is divided into two paths: one path enters the exhaust passage (i.e., the aforementioned exhaust flow passage 551) through the cavity between the cooling water jacket and the front bearing housing, and is finally discharged into the external environment; the other path blows up the flexible sealing ring through the annular sealing groove at the rear of the front radial bearing and enters the interior of the cooling water jacket, and exits with the water lubrication circuit.

[0071] Compressed air enters the rear radial bearing air supply channel through the main air supply channel, and then enters the front annular pressure equalization chamber of the rear radial bearing (i.e., the aforementioned pressure equalization annular chamber 452). It then enters the front annular pressure sealing groove of the rear radial bearing (i.e., the aforementioned first airflow annular groove 451) through several through holes (i.e., the aforementioned vent holes 453). The gas in the annular pressure sealing groove of the rear radial bearing is divided into two paths. One path passes through the gap between the rear radial bearing and the main shaft, enters the internal cavity of the main shaft (i.e., the aforementioned sealing accommodating space 100), and then passes through the air passage between the motor stator 21 and the motor rotor 22, and gathers in the internal water circuit of the cooling water jacket (i.e., the aforementioned annular cooling chamber 52), and is discharged with the water channel. The other path passes through the gap between the rear radial bearing and the main shaft, enters the front annular sealing groove of the rear radial bearing, and blows up the flexible sealing ring installed in the front annular sealing groove of the rear radial bearing. A layer of flowing gas is formed between the flexible sealing ring and the main shaft. This part of the sealing gas enters the front annular return water groove of the rear radial bearing and flows out with the lubricating water through the drainage channel.

[0072] According to an embodiment of the present invention, a machine tool is also provided, including the electric spindle described above.

[0073] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0074] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model. The above description is only a preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. An electric spindle, comprising a spindle core (1) and a housing fitted radially outward of the spindle core (1), wherein a drive motor is disposed within an annular space between the spindle core (1) and the housing, the drive motor comprising a motor stator (21) and a motor rotor (22), wherein, The stator core of the motor stator (21) is connected to the inner ring wall of the housing, and the motor rotor (22) is located on the outer ring wall of the shaft core (1). The shaft core (1) is supported in the housing via a front bearing (3) and a rear bearing (4). The housing is characterized by having a first cooling channel (51) formed inside the housing. The first cooling channel (51) has a portion located on the radially outer side of the stator core. The inner ring wall of the housing is also provided with an annular cooling cavity (52). The annular cooling cavity (52) is arranged around the shaft core (1) and is located between the front bearing (3) and the motor rotor (22).

2. The electric spindle according to claim 1, characterized in that, The first cooling channel (51) is a double-helix cross structure; and / or, the housing includes a cooling sleeve (531) and an outer sleeve (532) fitted on the outer circular wall of the cooling sleeve (531), the first cooling channel (51) is formed on the outer circular wall of the cooling sleeve (531), the stator core is assembled on the inner ring wall of the cooling sleeve (531), and the annular cooling cavity (52) is formed on the inner ring wall of the cooling sleeve (531).

3. The electric spindle according to claim 1, characterized in that, The annular cooling cavity (52) has at least one spacer ring (521) extending radially close to the shaft core (1) within it. The spacer ring (521) divides the annular cooling cavity (52) into a plurality of cooling sub-cavities spaced axially along the shaft core (1). An annular flow gap is formed between the spacer ring (521) and the shaft core (1) between two adjacent cooling sub-cavities.

4. The electric spindle according to claim 3, characterized in that, An annular groove (522) is formed on the inner annular surface of each of the spacer rings (521).

5. The electric spindle according to claim 1, characterized in that, Both the front bearing (3) and the rear bearing (4) are sliding bearings. The front bearing (3) has a first bearing cooling structure that communicates with the first cooling channel (51), and the rear bearing (4) has a second bearing cooling structure that communicates with the first cooling channel (51).

6. The electric spindle according to claim 5, characterized in that, The front bearing (3) is a radial bearing. The first bearing cooling structure includes a plurality of first cooling ring grooves (31) arranged sequentially from the middle region of the length of the front bearing (3) to the two sides of the length. Each first cooling ring groove (31) is arranged around the shaft core (1) and the groove opening of each first cooling ring groove (31) faces the shaft core (1).

7. The electric spindle according to claim 6, characterized in that, On the same first radial plane of the shaft core (1) at the inlet and outlet of the first bearing cooling structure, each of the first cooling ring grooves (31) is located on opposite sides of the first radial plane, and the volume of each of the first cooling ring grooves (31) increases along the direction away from the first radial plane, and / or each of the first cooling ring grooves (31) is symmetrically arranged about the first radial plane.

8. The electric spindle according to claim 6, characterized in that, The rear bearing (4) is a radial bearing, and the second bearing cooling structure includes a second cooling ring groove (41). The second cooling ring groove (41) is arranged around the shaft core (1) and the opening of the second cooling ring groove (41) faces the shaft core (1).

9. The electric spindle according to claim 8, characterized in that, The rear bearing (4) has an adjusting ring (42) and a bearing cover (43) on the side of the rear bearing (4) away from the motor rotor (22). The adjusting ring (42) is clamped between the bearing cover (43) and the rear bearing (4) to form an annular space between the rear bearing (4) and the bearing cover (43). A thrust disk (11) is fitted on the shaft core (1). The thrust disk (11) is located in the annular space. The second bearing cooling structure also includes a first branch cooling channel (441) formed in the rear bearing (4) and communicating with the annular space and / or a second branch cooling channel (442) communicating with the annular space in sequence via the rear bearing (4), the adjusting ring (42) and the bearing cover (43).

10. The electric spindle according to claim 8, characterized in that, The cooling medium flowing in the first cooling channel (51) and the annular cooling cavity (52) is cooling water. A first sealing ring (61) is provided between the inner ring wall of the housing and the shaft core (1), and a second sealing ring (62) is provided between the rear bearing (4) and the shaft core (1). A sealed accommodating space (100) is formed between the first sealing ring (61) and the second sealing ring (62). The drive motor is assembled in the sealed accommodating space (100), and the sealed accommodating space (100) is controllably connected to the pressurized gas. The pressurized gas entering the sealed accommodating space (100) can enter the annular cooling cavity (52) through the first sealing ring (61) and / or enter the second cooling ring groove (41) through the second sealing ring (62).

11. The electric spindle according to claim 10, characterized in that, Both the first sealing ring (61) and the second sealing ring (62) are unidirectional flexible sealing rings. The unidirectional flow direction of the first sealing ring (61) is from the motor rotor (22) to the annular cooling cavity (52), and the unidirectional flow direction of the second sealing ring (62) is from the motor rotor (22) to the rear bearing (4).

12. The electric spindle according to claim 11, characterized in that, The second sealing ring (62) is assembled on the rear bearing (4), and the rear bearing (4) is provided with a first airflow ring groove (451). The first airflow ring groove (451) and the second cooling ring groove (41) are respectively located on both sides of the second sealing ring (62). The first airflow ring groove (451) is located on the second sealing ring (62) near the motor rotor (22), and the groove opening of the first airflow ring groove (451) faces the shaft core (1) side; and / or, the flexible sealing ring has a mounting ring and a deformation ring located on the inner ring wall of the mounting ring and extending toward the shaft core (1) side, and the deformation ring is inclined toward its unidirectional flow direction side.

13. The electric spindle according to claim 12, characterized in that, The rear bearing (4) is provided with a uniform air pressure annular cavity (452). The uniform air pressure annular cavity (452) is concentrically arranged with the first airflow annular groove (451) and connected through a plurality of vent holes (453). Each of the vent holes (453) is evenly spaced along the circumferential direction of the first airflow annular groove (451). The pressurized gas is controllably connected to the uniform air pressure annular cavity (452).

14. The electric spindle according to claim 10, characterized in that, A second airflow annular groove (32) is also formed inside the front bearing (3). The second airflow annular groove (32) is arranged around the shaft core (1) and is located on the side of each of the first cooling annular grooves (31) close to the annular cooling cavity (52). The second airflow annular groove (32) is provided with a third sealing ring (63) and a fourth sealing ring (64) on both sides of the length of the shaft core (1). The third sealing ring (63) is located between the second airflow annular groove (32) and the first cooling annular groove (31), and the fourth sealing ring (64) is located between the second airflow annular groove (32) and the annular cooling cavity (52). Both the third sealing ring (63) and the fourth sealing ring (64) are unidirectional flexible sealing rings. The unidirectional flow direction of the third sealing ring (63) is from the second airflow annular groove (32) to the first cooling annular groove (31), and the unidirectional flow direction of the fourth sealing ring (64) is from the second airflow annular groove (32) to the annular cooling cavity (52).

15. The electric spindle according to claim 14, characterized in that, A sealed third airflow annular groove (33) is formed between the radial outer side of the front bearing (3) and the inner annular wall of the housing, and the third airflow annular groove (33) is connected to the second airflow annular groove (32).

16. The electric spindle according to claim 15, characterized in that, An exhaust channel (551) is formed inside the housing, and the exhaust channel (551) is connected to the third airflow annular groove (33); and / or, an inlet channel (552) is formed inside the housing, and the inlet of the sealed accommodating space (100) and the second airflow annular groove (32) is controllably connected to the inlet channel (552).

17. The electric spindle according to claim 5, characterized in that, The housing contains a cooling medium inlet channel (541) and a cooling medium outlet channel (542). The first cooling channel (51), the annular cooling cavity (52), the first bearing cooling structure and the second bearing cooling structure are connected in parallel between the cooling medium inlet channel (541) and the cooling medium outlet channel (542).

18. The electric spindle according to claim 1, characterized in that, A self-lubricating sealing ring (71) is provided between the front bearing (3) and the shaft core (1).

19. The electric spindle according to claim 1, characterized in that, The front bearing (3) is provided with a first temperature sensor for detecting its real-time temperature; and / or, the housing is also provided with a second temperature sensor for detecting the real-time temperature of the stator core.

20. A machine tool, characterized in that, The electric spindle includes any one of claims 1 to 19.

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