CN113000868A

CN113000868A - Assembly with hydraulic cylinder and center cooling for electric spindle

Info

Publication number: CN113000868A
Application number: CN202110271248.1A
Authority: CN
Inventors: 戴野; 王刚; 毛鑫涛; 李兆龙; 曲文印
Original assignee: Ningbo Tiankong Five Axis Cnc Technology Co ltd
Current assignee: Ningbo Tiankong Five Axis Cnc Technology Co ltd
Priority date: 2021-03-12
Filing date: 2021-03-12
Publication date: 2021-06-22
Anticipated expiration: 2041-03-12
Also published as: CN113000868B

Abstract

The invention discloses an electric spindle assembly with a hydraulic cylinder and central cooling, which comprises a first channel, wherein an end cover is provided with the first channel communicated with an accommodating cavity, an outer shell is provided with a second channel communicated with the accommodating cavity, a piston of the hydraulic cylinder can move along the axial direction of the inner shell by introducing hydraulic oil from the first channel or the second channel, a third channel is sequentially communicated with a fourth channel, a fifth channel and a seventh channel to form a liquid inlet passage, an eighth channel is sequentially communicated with a sixth channel, a ninth channel and a tenth channel to form a liquid outlet passage, a twelfth channel is communicated with the liquid outlet passage through a gap which is in contact with a spacing sleeve, and a thirteenth channel is communicated with the liquid inlet passage through a gap which is in contact with a top end gland. According to the invention, the hydraulic cylinder piston for controlling the broach device is combined with the central cooling structure for cooling the interior of the electric spindle, so that the integrated structure is more compact, single-channel inlet and multi-channel outlet of cooling liquid can be realized, and the cooling efficiency is further improved.

Description

Assembly with hydraulic cylinder and center cooling for electric spindle

Technical Field

The invention relates to the technical field of electric spindles, in particular to an electric spindle assembly with a hydraulic cylinder and center cooling.

Background

In the prior art, a hydraulic device for controlling a pull rod of an electric spindle and a cooling device of the electric spindle are complex in structure, are respectively assembled with the electric spindle, occupy large space and are inconvenient to install; meanwhile, the electric spindle cooling device can only cool the spindle shell but cannot cool the inside of the electric spindle rotating at a high speed, so that the temperature rise inside the electric spindle is large when the electric spindle works at a high speed, the overall performance of the spindle is reduced, and the service life of the electric spindle is short.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the above-mentioned problems in the prior art. Therefore, the invention provides the assembly for the electric spindle with the hydraulic cylinder and the central cooling function, which can save the occupied space of the assembly, make the whole structure more compact, and simultaneously can cool the internal structure of the assembly, thereby prolonging the service life and improving the reliability of the electric spindle using the assembly.

In order to achieve the purpose, the invention adopts the following technical scheme:

an electric spindle assembly with a hydraulic cylinder and center cooling, comprising: the end cover is provided with a protruding part, the end face of the protruding part is provided with a concave part, the outer shell is provided with a first cavity, the inner shell is provided with a second cavity, the inner shell is arranged in the outer shell, the inner shell and the outer shell are coaxially arranged to form a containing cavity used for containing the hydraulic cylinder piston, one end, provided with the protruding part, of the end cover extends into the second cavity, the end cover is fixedly connected with the end faces of the inner shell and the outer shell respectively, a first channel communicated with the containing cavity is arranged at a position, opposite to the hydraulic cylinder piston, of the end cover, a first shaft shoulder facing one side of the end cover is arranged on the inner wall of the outer shell, a protruding block is arranged at one end, close to the end cover, of the hydraulic cylinder piston, and the protruding block and the hydraulic cylinder piston are integrally formed, the two sides of the protruding block are respectively in sliding fit with the inner wall of the outer shell and the outer wall of the inner shell, the length of the protruding block is smaller than the distance between the first shaft shoulder and the end cover, a second channel communicated with the containing cavity is formed in the outer shell, the second channel is located on one side, close to the end cover, of the shaft shoulder, and hydraulic oil is introduced from the first channel or the second channel to enable the hydraulic cylinder piston to move along the axial direction of the inner shell;

the top end gland, the sealing disc, the limiting sleeve, the spacer bush, the rotary connecting piece, the supporting ring and the rotating shaft are sequentially arranged in the second cavity from one end fixed with the end cover to the other end, the top end gland is fixedly connected to the concave part, the sealing disc is fixedly connected to the convex part, the limiting sleeve is fixedly connected with the sealing disc, the spacer bush is abutted against the limiting sleeve, the protruding shaft is arranged at the middle shaft position of the rotary connecting piece, the protruding shaft is abutted against the top end gland, the rotary connecting piece is fixedly connected with the spacer bush, and the supporting ring used for limiting the movement of the rotary connecting piece far away from one end of the end cover is sleeved between the rotary connecting piece and the; one end of the rotating shaft extends into the second cavity from the end, opposite to the end cover fixed on the inner shell, and is fixedly connected with the rotating connecting piece, the outer wall of the rotating shaft is rotatably connected with the inner wall of the inner shell through a rotating device, and the rotating device plays a role in axially limiting the rotating shaft;

the end cover is provided with a third channel, the top end gland is provided with a fourth channel, the rotary connecting piece is provided with a fifth channel and a sixth channel which are mutually independent, the rotary shaft is provided with a seventh channel and an eighth channel which are mutually independent, the spacer bush is sleeved on the boss shaft and forms a ninth channel, the limiting bush is sleeved on the rotary connecting piece and forms a tenth channel, the end cover is also provided with an eleventh channel, the inner shell is also provided with a twelfth channel and a thirteenth channel which are used for communicating the eleventh channel and the second cavity, the third channel is sequentially communicated with the fourth channel, the fifth channel and the seventh channel and forms a liquid inlet passage, the eighth channel is sequentially communicated with the sixth channel, the ninth channel and the tenth channel to form a liquid outlet passage, and the twelfth channel is communicated with the liquid outlet passage through a gap which is mutually contacted between the limiting bush and the spacer bush, and the thirteenth channel is communicated with the liquid inlet passage through a gap which is pressed against the top end gland by the protruding shaft.

Further, be equipped with the first spacing post of threaded on the top gland, the depressed part has the first screw hole with first spacing post adaptation, first spacing post and first screw hole threaded connection, between top gland and the end cover the cover is equipped with first spring on the first spacing post.

Further, be equipped with the spacing post of threaded second on the stop collar, sealed have on the dish with the second screw hole of the spacing post adaptation of second, spacing post of second and second screw hole threaded connection, between stop collar and the sealed dish the cover is equipped with the second spring on the spacing post of second.

Further, be equipped with first compound sealing member between bellying axle that swivel connected coupler has and the top gland, first compound sealing member divide into two-layer body, two-layer body of first compound sealing member respectively with bellying axle and top gland fixed connection, and two-layer body is inconsistent.

Further, a second composite sealing element is arranged between the limiting sleeve and the spacer bush and is divided into two layers of bodies, the two layers of bodies of the second composite sealing element are fixedly connected with the limiting sleeve and the spacer bush respectively, and the two layers of bodies are abutted.

Furthermore, the first composite sealing element and the second composite sealing element are both made of ceramic materials.

Further, rotating device is including keeping off ring, gland, first bearing, annular retaining ring and second bearing, first bearing all locates with the second bearing between rotation axis and the interior shell inner wall, be provided with between first bearing and the second bearing annular retaining ring, first bearing with the shaft shoulder that rotation axis outer wall has is inconsistent, keep off the ring with the inner wall threaded connection of interior shell, the gland with the outer wall threaded connection of rotation axis, keep off ring and gland all be used for with second bearing, annular retaining ring and first bearing to the rotation axis is close to the end cover direction suppression.

Further, still include first wear ring and second wear ring, first wear ring sets up in between interior shell and the pneumatic cylinder piston, the second wear ring is located between shell body and the pneumatic cylinder piston.

Further, still include first oil blanket, second oil blanket and third oil blanket, first oil blanket is located between protruding piece and the interior shell body outer wall, the second oil blanket is located between protruding piece and the shell body inner wall, the third oil blanket is located between shell body inner wall and the pneumatic cylinder piston, and be located the first shoulder and keep away from one side of end cover.

Further, the sixth passageway is equipped with a plurality ofly, and is a plurality of the sixth passageway is that the annular array sets up around the fifth passageway, the eighth passageway also is equipped with a plurality ofly, and the eighth passageway equals with the sixth passageway quantity, and a plurality of sixth passageways correspond the intercommunication with a plurality of eighth passageways.

According to the technical scheme, compared with the prior art, the assembly for the electric spindle, which is provided with the hydraulic cylinder and has center cooling function, has the characteristic of integration, and the hydraulic cylinder piston for controlling the broach device and the center cooling structure for cooling the interior of the electric spindle are combined together, so that the integrated structure is more compact, the occupied space is small, the integrated structure is simple, the assembly is convenient, and the structural complexity is low; meanwhile, due to the arrangement of the plurality of sixth channels and the plurality of eighth channels, the cooling liquid can enter and exit from the single channel and multiple channels, so that the cooling efficiency is improved, the interior of the electric spindle is cooled aiming at two heat source motors and bearings in the electric spindle, the heating condition in the electric spindle is greatly improved, and the service life of the electric spindle is prolonged; and all adopt ceramic material to make through first compound sealing member and second compound sealing member, when the part of first compound sealing member and second compound sealing member both sides takes place relative rotation, can reduce the friction, reduce the wearing and tearing of part, make the leakproofness obtain guaranteeing.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic structural view of an electric spindle with a hydraulic cylinder and a center cooling module according to the present invention connected to the electric spindle;

FIG. 2 is an enlarged view of a portion of A of FIG. 1 in accordance with the present invention;

FIG. 3 is a schematic structural view of an inner housing provided in the present invention;

FIG. 4 is a schematic structural view of an end cap provided by the present invention;

FIG. 5 is a schematic structural view of a rotating shaft according to the present invention;

FIG. 6 is a schematic structural diagram of an outer casing according to the present invention;

fig. 7 is a schematic structural diagram of an electric spindle provided in the present invention.

Wherein: 1 is an end cover; 2 is a top end gland; 3 is a first limit column; 4 is a first spring; 5 is an inner shell; 6 is a first composite seal; 7 is a sealing disc; 8 is a limit sleeve; 9 is a second spring; 10 is a second limit column; 11 is a second composite seal; 12 is a spacer bush; 13 is a rotary connecting piece; 14 is a support ring; 15 is a rotating shaft; 16 is a first bearing; 17 is an annular retainer ring; 18 is a second bearing; 19 is a baffle ring; 20 is a gland; 21 is an outer shell; 22 is a second wear ring; 23 is a third oil sealing ring; 24 is a first wear ring; 25 is a hydraulic cylinder piston; 26 is a second oil seal ring; 27 is a first oil seal ring; 28 is a convex part; 29 is a recessed portion; 30 is a second cavity; 31 is a first channel; 32 is a second channel; a third channel 33; 34 is a fourth channel; 35 is a fifth channel; 36 is a sixth channel; 37 is a seventh channel; 38 is an eighth channel; 39 is a ninth channel; 40 is a tenth channel; 41 is an eleventh channel; 42 is a twelfth channel; 43 is a thirteenth channel; 44 is a fourteenth channel; 45 is a fifteenth channel; 46 is a sixteenth channel; 47 is a seventeenth channel; an eighteenth channel at 48; 49 is a sliding shaft; 50 is an electric spindle; 51 is a water diversion sleeve; and 52 is a spindle sealing cover.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-7, an embodiment of the invention discloses an electric spindle assembly with a hydraulic cylinder and center cooling, comprising: the end cover 1, an inner shell 5, an outer shell 21, a hydraulic cylinder piston 25, a top end gland 2, a sealing disc 7, a limiting sleeve 8, a spacer 12, a rotary connecting piece 13, a supporting ring 14 and a rotary shaft 15, wherein one end of the end cover 1 is provided with a convex part 28, the end surface of the convex part 28 is provided with a concave part 29, the outer shell 21 is provided with a first cavity, the inner shell 5 is provided with a second cavity 30, the inner shell 5 is arranged in the outer shell 21 and coaxially arranged with the outer shell 21 to form a containing cavity for containing the hydraulic cylinder piston 25, one end of the end cover 1 provided with the convex part 28 extends into the second cavity 30, the end cover 1 is respectively fixedly connected with the end surfaces of the inner shell 5 and the outer shell 21, a first channel 31 communicated with the containing cavity is arranged on the end cover 1 opposite to the hydraulic cylinder piston 25, a first shaft shoulder facing one side of the end cover 1 is arranged, protruding piece and pneumatic cylinder piston 25 integrated into one piece, the both sides of protruding piece respectively with the inner wall of shell body 21 and the 5 outer wall sliding fit in the shell body, the length of protruding piece is less than the distance between first shaft shoulder and the end cover 1, have on the shell body 21 with hold the second passageway 32 of chamber intercommunication, second passageway 32 is located the one side that the shaft shoulder is close to end cover 1, let in hydraulic oil through letting in from first passageway 31 or second passageway 32 and can make pneumatic cylinder piston 25 along the axial motion of interior casing 5.

A top end gland 2, a sealing disc 7, a limiting sleeve 8, a spacer 12, a rotary connecting piece 13, a supporting ring 14 and a rotating shaft 15 are sequentially arranged in the second cavity 30 from one end fixed with the end cover 1 to the other end, the top end gland 2 is fixedly connected to the concave part 29, the sealing disc 7 is fixedly connected to the convex part 28, the limiting sleeve 8 is fixedly connected with the sealing disc 7, the spacer 12 is abutted against the limiting sleeve 8, a convex shaft is arranged at the middle shaft position of the rotary connecting piece 13 and abutted against the top end gland 2, the rotary connecting piece 13 is fixedly connected with the spacer 12, and the supporting ring 14 used for limiting the rotary connecting piece 13 to move towards one end far away from the end cover 1 is sleeved between the rotary connecting piece 13 and the inner; one end of the rotating shaft 15 extends into the second cavity 30 from the end, opposite to the end cover 1, fixed on the inner shell 5 and is fixedly connected with the rotating connecting piece 13, the other end of the rotating shaft 15 is connected with a sliding shaft 49, the other end of the sliding shaft 49 extends into the cavity of the electric spindle 50, one end, far away from the rotating shaft 15, of the sliding shaft 49 is connected with the inner wall of the electric spindle 50 through a water distribution sleeve 51, one end, close to the rotating shaft 15, of the electric spindle 50 is sealed through a spindle sealing cover 52, the outer wall of the rotating shaft 15 is rotatably connected with the inner wall of the inner shell 5 through a rotating device, the rotating device has an axial limiting effect on the rotating shaft 15, wherein the rotating device comprises a retaining ring 19, a pressing cover 20, a first bearing 16, an annular retaining ring 17 and a second bearing 18, the first bearing 16 and the second bearing 18 are both arranged between the rotating shaft 15, the first bearing 16 is abutted against a shaft shoulder arranged on the outer wall of the rotating shaft 15, the baffle ring 19 is in threaded connection with the inner wall of the inner shell 5, the gland 20 is in threaded connection with the outer wall of the rotating shaft 15, and the baffle ring 19 and the gland 20 are used for pressing the second bearing 18, the annular retainer ring 17 and the first bearing 16 towards the direction that the rotating shaft 15 is close to the end cover 1.

The end cover 1 is provided with a third channel 33, the top end gland 2 is provided with a fourth channel 34, the rotary connecting piece 13 is provided with a fifth channel 35 and a sixth channel 36 which are mutually independent, the rotary shaft 15 is provided with a seventh channel 37 and an eighth channel 38 which are mutually independent, the spacer 12 is sleeved on the projection shaft and forms a ninth channel 39, the limiting sleeve 8 is sleeved on the rotary connecting piece 13 and forms a tenth channel 40, the end cover 1 is further provided with an eleventh channel 41, the inner shell 5 is further provided with a twelfth channel 42 and a thirteenth channel 43 which are used for communicating the eleventh channel 41 and the second cavity 30, the third channel 33 is sequentially communicated with the fourth channel 34, the fifth channel 35 and the seventh channel 37 and forms a liquid inlet passage, the eighth channel 38 is sequentially communicated with the sixth channel 36, the ninth channel 39 and the tenth channel 40 to form a liquid outlet passage, the twelfth channel 42 is communicated with the liquid outlet passage through a gap which is abutted between the limiting sleeve 8 and the spacer 12, the thirteenth channel 43 is communicated with the liquid inlet channel through the gap between the protruding shaft and the top end gland 2, specifically, a part of the cooling liquid in the liquid inlet channel flows out through the gap between the top end gland 2 and the rotary connecting piece 13, flows out through the gap between the top end gland 2 and the protruding part 28 of the end cover 1, flows to the thirteenth channel 43 on the inner shell 5 through the gap between the end cover 1 and the inner shell 5, finally flows out through the eleventh channel 41 on the end cover 1, the cooling liquid on the liquid outlet channel is divided into two channels, one channel flows out through the gap between the limiting sleeve 8 and the spacer 12, finally flows to the eleventh channel 41 on the end cover 1 through the twelfth channel 42 on the inner shell 5, and finally flows out, the other channel flows to the gap between the end cover 1 and the inner shell 5 through the tenth channel 40 and through the gap between the sealing disk 7 and the end cover 1, and flows from the thirteenth channel 43 to the eleventh channel 41 and finally flows out, meanwhile, the sliding shaft 49 is provided with a fourteenth channel 44, a fifteenth channel 45 and a sixteenth channel 46, the water dividing sleeve 51 is provided with a seventeenth channel 47, the electric spindle 50 is provided with an eighteenth channel 48, wherein, one end of the fourteenth channel 44 is communicated with the seventh channel 37 on the rotating shaft 15, the other end of the fourteenth channel 44 is communicated with the seventeenth channel 47 on the water dividing sleeve 51 through the fifteenth channel 45, the eighteenth channel 48 on the electric spindle 50 is used for communicating the seventeenth channel 47 on the water dividing sleeve 51 with one end of the sixteenth channel 46 on the sliding shaft 49, the other end of the sixteenth channel 46 is used for communicating with the eighth channel 38 on the rotating shaft 15, namely, the liquid inlet passage is communicated with the liquid outlet passage through the fourteenth passage 44, the fifteenth passage 45, the seventeenth passage 47, the eighteenth passage 48 and the sixteenth passage 46 in sequence to form a circulation loop.

In the present embodiment, there are four sixth channels 36, four fifth channels 35 are disposed at the central axis position of the rotating connecting member 13, four sixth channels 36 are disposed around the fifth channel 35 in an annular array, four eighth channels 38 are also disposed, and four sixth channels 36 are correspondingly communicated with four eighth channels 38, and similarly, there are four sixteenth channels 46 and eighteenth channels 48, and each sixteenth channel 46 is used for communicating the corresponding eighth channel 38 on the rotating shaft 15 with the corresponding eighteenth channel 48 on the electric spindle 50. In other embodiments, the sixth channel 36, the eighth channel 38, the sixteenth channel 46 and the eighteenth channel 48 may be provided with other numbers according to actual requirements, and the specific number is not specifically limited herein.

In the above embodiment, the top end gland 2 is provided with the first limiting column 3 with threads, the recessed portion 29 is provided with the first threaded hole matched with the first limiting column 3, the first limiting column 3 is in threaded connection with the first threaded hole, the first limiting column 3 between the top end gland 2 and the end cover 1 is sleeved with the first spring 4, the first limiting column 3 can relatively fix the positions of the top end gland 2 and the end cover 1, the first spring 4 can buffer the vibration generated in the rotation process of the rotating connecting piece 13, the rotating shaft 15 and the like, and meanwhile, the top end gland 2 tends to the elastic force in the direction of the rotating connecting piece 13; threaded second spacing post 10 is equipped with on the stop collar 8, have on the sealed dish 7 with the second screw hole of the spacing post 10 adaptation of second, spacing post 10 of second and second screw hole threaded connection, the cover is equipped with second spring 9 on the spacing post 10 of second between stop collar 8 and the sealed dish 7, the position relatively fixed of sealed dish 7 and stop collar 8 can be realized to the spacing post 10 of second, second spring 9's effect can be to rotation axis 15, the produced vibration of rotation piece rotation in-process such as swivelling joint spare 13 plays cushioning effect, have an elasticity that tends to the 12 directions of spacer simultaneously to stop collar 8.

Specifically, a first composite sealing element 6 is arranged between a protruding shaft and a top end gland 2 which are arranged on a rotary connecting piece 13, the first composite sealing element 6 is divided into two layers of bodies, the two layers of bodies of the first composite sealing element 6 are respectively and fixedly connected with the protruding shaft and the top end gland 2 and are abutted against each other, a second composite sealing element 11 is arranged between a limiting sleeve 8 and a spacer 12, the second composite sealing element 11 is divided into two layers of bodies, the two layers of bodies of the second composite sealing element 11 are respectively and fixedly connected with the limiting sleeve 8 and the spacer 12 and are abutted against each other, the first composite sealing element 6 and the second composite sealing element 11 are both made of ceramic materials, because the first composite sealing element 6 and the second composite sealing element 11 are both formed by two layers of bodies which are respectively fixed on two opposite rotating pieces which are abutted against each other, namely the top end gland 2, the rotary connecting piece 13, the limiting sleeve 8 and the spacer 12, in the rotating process of the components such as the rotating connecting piece 13, the rotating shaft 15 and the like, an oil film can be formed between the two layers of bodies, the lubricating effect is achieved, the high-speed rotating efficiency of the rotating part is guaranteed, the sealing effect is achieved, and the cooling liquid is prevented from leaking to a large extent.

The assembly for the electric spindle 50 with the hydraulic cylinder and the center cooling disclosed in the above embodiment further includes the first wear ring 24 and the second wear ring 22, the first wear ring 24 is disposed between the inner housing 5 and the cylinder piston 25, and the second wear ring 22 is disposed between the outer housing 21 and the cylinder piston 25.

The assembly for the electric spindle 50 with the hydraulic cylinder and the center cooling disclosed in the above embodiment further includes a first oil seal ring 27, a second oil seal ring 26, and a third oil seal ring 23, the first oil seal ring 27 is disposed between the bump and the outer wall of the inner housing 5, the second oil seal ring 26 is disposed between the bump and the inner wall of the outer housing 21, and the third oil seal ring 23 is disposed between the inner wall of the outer housing 21 and the hydraulic cylinder piston 25 and is located on one side of the first shoulder away from the end cap 1.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electric spindle assembly with a hydraulic cylinder and center cooling, comprising: the end cover is provided with a protruding part, the end face of the protruding part is provided with a concave part, the outer shell is provided with a first cavity, the inner shell is provided with a second cavity, the inner shell is arranged in the outer shell, the inner shell and the outer shell are coaxially arranged to form a containing cavity used for containing the hydraulic cylinder piston, one end, provided with the protruding part, of the end cover extends into the second cavity, the end cover is fixedly connected with the end faces of the inner shell and the outer shell respectively, a first channel communicated with the containing cavity is arranged at a position, opposite to the hydraulic cylinder piston, of the end cover, a first shaft shoulder facing one side of the end cover is arranged on the inner wall of the outer shell, a protruding block is arranged at one end, close to the end cover, of the hydraulic cylinder piston, and the protruding block and the hydraulic cylinder piston are integrally formed, the two sides of the protruding block are respectively in sliding fit with the inner wall of the outer shell and the outer wall of the inner shell, the length of the protruding block is smaller than the distance between the first shaft shoulder and the end cover, a second channel communicated with the containing cavity is formed in the outer shell, the second channel is located on one side, close to the end cover, of the shaft shoulder, and hydraulic oil is introduced from the first channel or the second channel to enable the hydraulic cylinder piston to move along the axial direction of the inner shell;

2. The assembly of claim 1, wherein the top end cap has a first threaded stop post, the recess has a first threaded hole adapted to the first stop post, the first stop post is in threaded connection with the first threaded hole, and a first spring is sleeved on the first stop post between the top end cap and the end cap.

3. The assembly for the electric spindle with the hydraulic cylinder and the center cooling function according to claim 1, wherein a second limiting column with threads is mounted on the limiting sleeve, a second threaded hole matched with the second limiting column is formed in the sealing disc, the second limiting column is in threaded connection with the second threaded hole, and a second spring is sleeved on the second limiting column between the limiting sleeve and the sealing disc.

4. The assembly of claim 1, wherein a first composite sealing element is arranged between the protruding shaft and the top end gland of the rotating connecting piece, the first composite sealing element is divided into two layers of bodies, the two layers of bodies of the first composite sealing element are fixedly connected with the protruding shaft and the top end gland respectively, and the two layers of bodies are in contact with each other.

5. The assembly for the electric spindle with the hydraulic cylinder and the central cooling function according to claim 4, wherein a second composite sealing element is arranged between the limiting sleeve and the spacer sleeve, the second composite sealing element is divided into two layers of bodies, the two layers of bodies of the second composite sealing element are fixedly connected with the limiting sleeve and the spacer sleeve respectively, and the two layers of bodies are abutted against each other.

6. The assembly of claim 5, wherein the first and second composite seals are made of a ceramic material.

7. The assembly for the electric spindle with the hydraulic cylinder and the center cooling function according to claim 1, wherein the rotating device comprises a retaining ring, a gland, a first bearing, an annular retaining ring and a second bearing, the first bearing and the second bearing are both arranged between the rotating shaft and the inner wall of the inner shell, the annular retaining ring is arranged between the first bearing and the second bearing, the first bearing is abutted against a shaft shoulder on the outer wall of the rotating shaft, the retaining ring is in threaded connection with the inner wall of the inner shell, the gland is in threaded connection with the outer wall of the rotating shaft, and the retaining ring and the gland are used for pressing the second bearing, the annular retaining ring and the first bearing towards the direction that the rotating shaft is close to the end cover.

8. The assembly for an electric spindle with a hydraulic cylinder and center cooling of claim 1, further comprising a first wear ring and a second wear ring, wherein the first wear ring is disposed between the inner housing and the cylinder piston, and the second wear ring is disposed between the outer housing and the cylinder piston.

9. The assembly for the electric spindle with the hydraulic cylinder and the center cooling function according to claim 1, further comprising a first oil seal ring, a second oil seal ring and a third oil seal ring, wherein the first oil seal ring is arranged between the bulge block and the outer wall of the inner shell, the second oil seal ring is arranged between the bulge block and the inner wall of the outer shell, and the third oil seal ring is arranged between the inner wall of the outer shell and the piston of the hydraulic cylinder and is located on one side, away from the end cover, of the first shaft shoulder.

10. The assembly for an electric spindle with a hydraulic cylinder and center cooling according to claim 1, wherein the sixth channel is provided in plurality, the sixth channels are arranged around the fifth channel in an annular array, the eighth channel is provided in plurality, the number of the eighth channels is equal to the number of the sixth channels, and the sixth channels are correspondingly communicated with the eighth channels.