A spindle for CNC machine tools

Abstract

The invention discloses a CNC machine tool spindle, comprising a hollow spindle, a spindle sleeve, a motor, a first front bearing, a second front bearing, a first rear bearing, a second rear bearing and a knife-beating cylinder unit, a plurality of preload springs are arranged between the first sliding sleeve and the front bearing seat, a cooling sleeve is connected to the inner side of the rear bearing seat, a motor heat insulation sleeve is connected to the inner side of the spindle sleeve, a first cooling ring groove on the outer wall of the cooling sleeve is connected to the second cooling ring groove on the outer wall of the motor heat insulation sleeve through a plurality of cooling pipelines, a plurality of first oil-gas lubrication branches are respectively arranged on the front and rear sides of each first front bearing and each second front bearing, and a plurality of second oil-gas lubrication branches are respectively arranged on the front and rear sides of each first rear bearing and each second rear bearing. The CNC machine tool spindle of the invention can greatly alleviate the temperature rise problem of the bearing, thereby extending the bearing life, improving the parts processing efficiency and processing accuracy, and ensuring the performance and life of the bearing under high speed and high load conditions.

Description

Technical Field

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

[0002] As an important functional component in CNC machine tools, the spindle plays a key role in parts processing. During the installation of the spindle, the front and rear bearings installed on the spindle need to be preloaded. At present, the spindles on the market are mainly divided into two types: positioning preload and constant pressure preload, according to the different bearing preload methods. Among them, the oil-gas lubrication constant pressure preload spindle is a representative of high-speed and high-performance spindles. The domestic market mainly relies on imports and lacks independent production capabilities. In order to meet the structural requirements of oil-gas lubrication and constant pressure preload, the existing constant pressure preload spindles usually design cooling structures for the outer ring of the front bearing. Some front bearings even have no cooling structure and only cool the bearings through oil-gas lubricating oil, resulting in a reduction in bearing life and affecting part processing efficiency. The existing constant pressure preload spindle only considers the external heat dissipation of the motor (that is, only the heat is dissipated on the periphery of the spindle sleeve), ignoring the heat transfer between the motor and the bearing. When the spindle is in a high-speed rotating working state, the stator of the motor will also generate a lot of heat, resulting in a temperature rise of the front and rear bearings on the spindle, affecting the bearing life and part processing efficiency. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a CNC machine tool spindle, which can alleviate the temperature rise problem of the spindle bearings to a great extent, thereby extending the bearing life, improving the parts processing efficiency and processing accuracy, and ensuring the performance and life of the bearings under high speed and high load conditions.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: a CNC machine tool spindle, including a hollow spindle, a spindle sleeve, a motor, a first front bearing, a second front bearing, a first rear bearing, a second rear bearing and a knife-beating cylinder unit, wherein the first front bearing and the second front bearing are installed at a front section of the spindle at a front-to-back interval, and the first rear bearing and the second rear bearing are installed at a front-to-back interval on the rear section of the spindle, a front bearing seat is installed on the outer side of the first front bearing and the second front bearing, and a rear bearing seat is installed on the outer side of the first rear bearing and the second rear bearing, and the A first sliding sleeve is fixed to the outer side of the second front bearing, the front end surface of the first sliding sleeve is in contact with the front bearing seat, and a second sliding sleeve is fixed to the outer side of the first rear bearing and the second rear bearing. The motor is installed in the middle and rear section of the spindle. The motor includes a stator and a rotor. The rotor is connected to the outer side of the spindle by interference fit. The spindle sleeve is connected to the outer side of the stator by interference fit. The front and rear ends of the spindle sleeve are respectively connected to the front bearing seat and the rear bearing seat for centering. The knife-beating cylinder unit is arranged on the rear side of the spindle. , the knife-beating cylinder unit is used to realize the knife-releasing and clamping function of the spindle, a plurality of preload springs are evenly arranged between the front end surface of the first sliding sleeve and the front bearing seat, a cooling sleeve is centrally connected to the inner side of the front bearing seat, the cooling sleeve is arranged between the first front bearing and the second front bearing, a motor heat-insulating sleeve is centrally connected to the inner side of the spindle sleeve, the motor heat-insulating sleeve is arranged on the outer side of the spindle and located on the front side of the motor, a first cooling ring groove is arranged on the outer wall of the cooling sleeve, a second cooling ring groove is arranged on the outer wall of the motor heat-insulating sleeve, the The first cooling ring groove is connected with the second cooling ring groove via a plurality of cooling pipes, the plurality of cooling pipes are opened in the front bearing seat and the main shaft sleeve, the plurality of cooling pipes are connected with an external cooling water supply mechanism, the front and rear sides of each of the first front bearings and each of the second front bearings are respectively provided with a plurality of first oil-gas lubrication branches, the front and rear sides of each of the first rear bearings and each of the second rear bearings are respectively provided with a plurality of second oil-gas lubrication branches, the plurality of first oil-gas lubrication branches and the plurality of second oil-gas lubrication branches are both connected with an external air extraction mechanism.

[0005] The CNC machine tool spindle of the present invention is designed with a cooling sleeve and a motor insulation sleeve, a first cooling ring groove is designed on the outer wall of the cooling sleeve, a second cooling ring groove is designed on the outer wall of the motor insulation sleeve, and a plurality of cooling pipelines are designed to connect the first cooling ring groove with the second cooling ring groove to form a water-cooled circulating cooling loop, which can effectively absorb the heat of the first front bearing and the second front bearing which generate relatively large heat when the spindle is working and the heat of the motor stator, control the heating of the bearings, and greatly alleviate the temperature rise problem of the spindle bearings, thereby extending the bearing life and improving the parts processing efficiency and processing accuracy. At the same time, based on the good cooling effect of the water-cooled circulation cooling circuit formed by the first cooling ring groove, several cooling pipes and the second cooling ring groove, several first oil-gas lubrication branches and several second oil-gas lubrication branches can smoothly discharge the oil and gas in the first front bearing, the second front bearing, the first rear bearing and the second rear bearing, and take away the heat of the first front bearing, the second front bearing, the first rear bearing and the second rear bearing, avoiding abnormal temperature rise due to excessive oil accumulation in the bearing raceway, thereby further enhancing the cooling effect of the bearings and ensuring the performance and life of the first front bearing, the second front bearing, the first rear bearing and the second rear bearing under high speed and high load conditions.

[0006] The CNC machine tool spindle of the present invention is a constant-pressure preloaded spindle. Different from the conventional constant-pressure preloaded spindle in which the preloaded spring acts directly on the bearing, the present invention provides the preloaded force through a plurality of preloaded springs. In order to stabilize the preloaded force, the present invention makes the preloaded spring act evenly on the first sliding sleeve, so that the preloaded force can act evenly on the outer ring of the second front bearing, and can also minimize the error influence caused by a single preloaded spring, so that the working state of the spindle is more stable when running at high speed.

[0007] Preferably, the first front bearing, the second front bearing, the first rear bearing and the second rear bearing are respectively interference fit with the outer circle of the main shaft, the outer circles of the front section and the rear section of the main shaft are respectively provided with a first step shoulder and a second step shoulder, the rear end face of the inner ring of the second front bearing contacts with the first step shoulder, the front end and the rear end of the outer ring of the second front bearing are respectively pressed by the first sliding sleeve and the first rear pressure cover, the first sliding sleeve and the second front bearing are clearance-centered fit, the front bearing seat and the outer circle of the first sliding sleeve are clearance-centered fit, the first rear pressure cover is centeringly connected to the rear end of the first sliding sleeve, a first spacer sleeve is pressed between the inner ring of the first front bearing and the inner ring of the second front bearing, the first spacer sleeve is clearance-matched with the outer circle of the main shaft, and the cooling sleeve is arranged on the outside of the first spacer sleeve The front end of the inner ring of the first front bearing is pressed by the inner pressure cover, which is fixed to the front end of the main shaft by threads. The front end and rear end of the outer ring of the first front bearing are pressed by the outer pressure cover and the front bearing seat respectively. The outer pressure cover is fixed to the front bearing seat. The front end of the outer pressure cover is pressed by the front cover. The front cover and the outer pressure cover are fixedly connected to the front bearing seat. The front end surface of the inner ring of the first rear bearing is in contact with the second step shoulder. A second spacer is pressed between the inner ring of the first rear bearing and the inner ring of the second rear bearing. The second spacer is matched with the outer circle clearance of the main shaft. The rear end of the inner ring of the second rear bearing is pressed by the second rear pressure cover, which is fixed to the rear end of the main shaft and matched with the outer circle of the main shaft. The rear bearing seat is matched with the outer circle of the second sliding sleeve. The above technical scheme can ensure the installation accuracy of key parts such as the first front bearing, the second front bearing, the first rear bearing, and the second rear bearing, and ensure the stability of the structure and performance of the main shaft.

[0008] Preferably, a plurality of first angular locating pins are connected between the cooling sleeve and the front bearing seat, a plurality of second angular locating pins are connected between the motor heat insulation sleeve and the main shaft sleeve, a plurality of third angular locating pins are connected between the outer pressure cover and the front bearing seat, a plurality of fourth angular locating pins are connected between the first sliding sleeve and the first rear pressure cover, and a plurality of fifth angular locating pins are connected between the second sliding sleeve and the rear bearing seat. The plurality of first angular locating pins, the plurality of second angular locating pins, the plurality of third angular locating pins, the plurality of fourth angular locating pins and the plurality of fifth angular locating pins can limit the axial freedom between the above-mentioned related parts and ensure the assembly accuracy of the parts.

[0009] Preferably, a first labyrinth gap is provided between the front end cover, the outer pressure cover and the inner pressure cover, a second labyrinth gap is provided between the outer pressure cover and the inner pressure cover, the front end of the second labyrinth gap is communicated with the radial middle part of the first labyrinth gap, the rear end of the second labyrinth gap is opposite to the front side of the first front bearing, the radial outer edge of the first labyrinth gap is connected with a first reflow groove, the radial inner edge of the first labyrinth gap is connected with a second reflow groove, the second reflow groove is communicated with the outside atmosphere, a nose end air seal channel is opened in the outer pressure cover, one end of the nose end air seal channel is communicated with the second labyrinth gap, and the other end of the nose end air seal channel is communicated with an external air source. The front end cover, the outer pressure cover and the inner pressure cover form a spindle nose end air sealing structure with a reflux groove. The first reflux groove and the second reflux groove reduce the speed at which the cutting fluid invades the spindle. At the same time, an external air source introduces positive pressure into the interior of the spindle through the nose end air sealing channel to supplement the vacuum area generated when the spindle rotates at high speed. The pressurized gas introduced into the nose end air sealing channel eventually passes through the second reflux groove to the outside of the spindle, preventing external impurities from entering the interior of the spindle, thereby ensuring the airtightness, reliability and stability of the spindle.

[0010] Preferably, the several first oil-gas lubrication branches are connected to an external air pumping mechanism, the several second oil-gas lubrication branches are connected to an external air pumping mechanism, the first oil-gas lubrication branch on the front side of the first front bearing is opened in the external pressure cover, the first oil-gas lubrication branch on the rear side of the first front bearing is opened in the front bearing seat, the first oil-gas lubrication branch on the front side of the second front bearing is opened in the first sliding sleeve, the first oil-gas lubrication branch on the rear side of the second front bearing is opened in the first rear pressure cover, the second oil-gas lubrication branch on the front side of the first rear bearing is opened in the rear bearing seat, the second oil-gas lubrication branch on the rear side of the first rear bearing, the second oil-gas lubrication branch on the front side of the second rear bearing and the second oil-gas lubrication branch on the rear side of the second rear bearing are all opened in the second sliding sleeve.

[0011] Preferably, an outer spacer is provided on the outer side of the second spacer, and a communicating radial guide groove and an axial guide groove are provided in the outer spacer, the front end and the rear end of the axial guide groove are respectively opposite to the rear side of the first rear bearing and the front side of the second rear bearing, and the second oil and gas lubrication branch on the rear side of the first rear bearing and the second oil and gas lubrication branch on the front side of the second rear bearing are merged into a common branch, which is communicated with the radial guide groove.

[0012] Preferably, the knife beating cylinder unit comprises a knife beating cylinder, a knife pulling rod, a knife pulling claw and a knife loosening spring. A plurality of connecting rods are fixed to the front end of the piston of the knife beating cylinder. The plurality of connecting rods pass through the second rear pressure cover and are connected to the knife pulling rod. The knife pulling rod is arranged on the inner side of the spindle. A limiting boss is radially provided at the rear end of the knife pulling rod. A third step shoulder is provided at the inner circle of the front section of the spindle. A transition sleeve and a spring spacer are provided for centering at the front and rear ends of the knife pulling rod. The transition sleeve is centering with the inner circle of the spindle. A radial through hole is provided in the transition sleeve. A conical handle blowing hole is provided at the front end of the spindle. When the spindle performs the knife loosening action, the knife pulling rod moves toward the After the front end of the main shaft moves into place, the radial through hole is connected with the blowing hole of the tapered handle, the front end face of the spring spacer is in contact with the shoulder of the third step, the loosening knife spring sleeve is arranged on the broaching rod, the rear end of the loosening knife spring is in contact with the front end face of the limiting boss, the front end of the loosening knife spring is in contact with the rear end face of the spring spacer, the front end of the broaching rod is threadedly connected with the limiting nut, the limiting nut is located between the transition sleeve and the spring spacer, a gap is reserved between the rear end face of the limiting nut and the front end face of the spring spacer, the broaching claw is threadedly connected with the front end of the broaching rod, and the front end of the broaching claw is used for installing the tool.

[0013] Preferably, the knife pulling rod is a hollow knife pulling rod, the rear end of the knife hitting cylinder is installed with a central water outlet rotating joint, the middle part of the second rear pressure cover is integrally provided with a central water outlet connecting pipe, the rear end of the central water outlet connecting pipe is sealed and connected to the water outlet of the central water outlet rotating joint, and the front end of the central water outlet connecting pipe is communicated with the inner hole of the knife pulling rod. The traditional main shaft with center water outlet function has a center water outlet connecting pipe and a rear bearing pressure cover as a split structure. The center water outlet connecting pipe is fixed to the tool pulling rod by threads and moves with the tool pulling rod. With the increase in the number of times the tool is loosened and clamped, the center water outlet connecting pipe moves frequently relative to the center water outlet rotating joint. The connection between the center water outlet connecting pipe and the center water outlet rotating joint may cause damage to the bearings and seals built into the center water outlet rotating joint due to frequent wear caused by loosening and clamping the tool. To avoid this phenomenon, the present invention integrates the center water outlet connecting pipe and the second rear pressure cover into one part. When the main shaft loosens and clamps the tool, the tool pulling rod follows the piston action of the tool hitting cylinder, and the second rear pressure cover and the center water outlet connecting pipe remain stationary. There is no relative movement between the two, thereby effectively avoiding damage to the bearings and seals built into the center water outlet rotating joint, preventing water from entering the main shaft, and effectively improving the service life of the center water outlet rotating joint and the stability of the main shaft.

[0014] Compared with the prior art, the present invention has the following advantages: the CNC machine tool spindle of the present invention is designed with a cooling sleeve and a motor heat insulation sleeve, a first cooling ring groove is designed on the outer wall of the cooling sleeve, a second cooling ring groove is designed on the outer wall of the motor heat insulation sleeve, and a plurality of cooling pipelines are designed to connect the first cooling ring groove with the second cooling ring groove to form a water-cooled circulation cooling circuit, which can effectively absorb the heat of the first front bearing and the second front bearing, which generate relatively large heat when the spindle is working, and the heat of the motor stator, control the heating of the bearings, and greatly alleviate the temperature rise problem of the spindle bearings, thereby extending the bearing life and improving the processing efficiency and processing accuracy of parts. At the same time, the plurality of first oil-gas lubrication branches and the plurality of second oil-gas lubrication branches can smoothly discharge the oil and gas in the first front bearing, the second front bearing, the first rear bearing, and the second rear bearing, take away the heat, and avoid abnormal temperature rise due to excessive oil accumulation in the bearing raceway, thereby further strengthening the bearing cooling effect and ensuring the performance and life of the first front bearing, the second front bearing, the first rear bearing, and the second rear bearing under high speed and high load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the spindle of the CNC machine tool in the embodiment;

[0016] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0017] Figure 3 for Figure 1 Enlarged view of point B in the middle;

[0018] Figure 4 for Figure 1 Enlarged view of point C in the middle;

[0019] Figure 5 Schematic diagram of the first oil-gas lubrication branches at the front and rear sides of the first front bearing and the second front bearing in the embodiment;

[0020] Figure 6 Schematic diagram of the appearance of the second rear pressure cover and the knife-beating cylinder in the embodiment;

[0021] The specific reference numerals in the figure are as follows:

[0022] 1-spindle, 11-spindle sleeve, 12-motor insulation sleeve, 13-second cooling ring groove, 14-cooling pipeline, 15-first step shoulder, 16-second step shoulder, 17-third step shoulder, 18-inner pressure cover, 19-outer pressure cover, 191-nose end gas seal channel, 10-front end cover, 21-stator, 22-rotor, 31-first front bearing, 32-second front bearing, 33-front bearing seat, 34-first sliding sleeve, 35-preload spring, 36-cooling sleeve, 37-first cooling ring groove, 38-first oil and gas lubrication branch, 39-first rear pressure cover, 30-first spacer, 41-first rear bearing, 42-second rear bearing, 43-rear bearing seat, 44-second sliding sleeve, 45-second oil and gas lubrication branch, 46- The second spacer, 47-the second rear pressure cover, 471-the central water outlet connecting pipe, 48-the outer spacer, 49-the radial guide groove, 40-the axial guide groove, 401-the common branch, 51-the first labyrinth gap, 52-the second labyrinth gap, 53-the first reflow groove, 54-the second reflow groove, 6-the knife-beating cylinder, 61-the knife-pulling rod, 62-the knife-pulling claw, 63-the knife-loosening spring, 64-the connecting rod, 65-the limiting boss, 66-the transition sleeve, 67-the spring spacer, 68-the radial through hole, 69-the cone handle blowing hole, 60-the limiting nut, 71-the first angular positioning pin, 72-the second angular positioning pin, 73-the third angular positioning pin, 74-the fourth angular positioning pin, 75-the fifth angular positioning pin, 81-the central water outlet rotary joint, 82-the tool. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the embodiments of the drawings. All structures or components not limited in the present invention adopt conventional technical means in the art.

[0024] The CNC machine tool spindle of the embodiment is a constant pressure preloaded spindle with a central water outlet function, as shown in the figure, comprising a hollow spindle 1, a spindle sleeve 11, a motor, a first front bearing 31, a second front bearing 32, a first rear bearing 41, a second rear bearing 42 and a knife-beating cylinder unit, the first front bearing 31 and the second front bearing 32 are installed at a front section of the spindle 1 at a front-to-back interval, the first rear bearing 41 and the second rear bearing 42 are installed at a front-to-back interval on the rear section of the spindle 1, the front bearing seat 33 is installed on the outer side of the first front bearing 31 and the second front bearing 32, the rear bearing seat 43 is installed on the outer side of the first rear bearing 41 and the second rear bearing 42, and the outer side of the second front bearing 32 is fixed A first sliding sleeve 34 is fixed, the front end face of the first sliding sleeve 34 contacts the front bearing seat 33, the outer sides of the first rear bearing 41 and the second rear bearing 42 are fixed with a second sliding sleeve 44, the motor is installed in the middle and rear section of the main shaft 1, the motor includes a stator 21 and a rotor 22, the rotor 22 is connected to the outer side of the main shaft 1 by interference fit, the main shaft sleeve 11 is connected to the outer side of the stator 21 by interference fit, the front end and rear end of the main shaft sleeve 11 are respectively connected to the front bearing seat 33 and the rear bearing seat 43 for centering, the knife-breaking cylinder unit is arranged on the rear side of the main shaft 1, the knife-breaking cylinder unit is used to realize the knife-loosening function of the main shaft 1, the front end face of the first sliding sleeve 34 and the front bearing seat 33 are evenly distributed. A plurality of preload springs 35 are arranged, a cooling sleeve 36 is connected to the inner side of the front bearing seat 33 in a centering manner, a plurality of first angular positioning pins 71 are connected between the cooling sleeve 36 and the front bearing seat 33, the cooling sleeve 36 is arranged between the first front bearing 31 and the second front bearing 32, a motor heat insulation sleeve 12 is connected to the inner side of the main shaft sleeve 11 in a centering manner, a plurality of second angular positioning pins 72 are connected between the motor heat insulation sleeve 12 and the main shaft sleeve 11, the motor heat insulation sleeve 12 is arranged on the outer side of the main shaft 1 and is located on the front side of the motor, and only a small gap of 1 mm is left between the motor heat insulation sleeve 12 and the stator 21 of the motor, a first cooling ring groove 37 is arranged on the outer wall of the cooling sleeve 36, and the motor A second cooling ring groove 13 is provided on the outer wall of the machine insulation sleeve 12, and the first cooling ring groove 37 is connected with the second cooling ring groove 13 via a plurality of cooling pipes 14, and the plurality of cooling pipes 14 are opened in the front bearing seat 33 and the main shaft sleeve 11, and the plurality of cooling pipes 14 are connected with an external cooling water supply mechanism, and a plurality of first oil-gas lubrication branches 38 are respectively provided on the front and rear sides of each first front bearing 31 and each second front bearing 32, and a plurality of second oil-gas lubrication branches 45 are respectively provided on the front and rear sides of each first rear bearing 41 and each second rear bearing 42, and the plurality of first oil-gas lubrication branches 38 and the plurality of second oil-gas lubrication branches 45 are all connected with an external air extraction mechanism.

[0025] In this embodiment, the first front bearing 31, the second front bearing 32, the first rear bearing 41 and the second rear bearing 42 adopt a DB combination method to ensure that the main shaft 1 can still obtain greater rigidity when working at a high speed, and the first front bearing 31, the second front bearing 32, the first rear bearing 41 and the second rear bearing 42 are respectively interference fit with the outer circle of the main shaft 1, and the outer circles of the front section and the rear section of the main shaft 1 are respectively provided with a first step shoulder 15 and a second step shoulder 16, the rear end face of the inner ring of the second front bearing 32 is in contact with the first step shoulder 15, and the front end of the outer ring of the second front bearing 32 is in contact with the first step shoulder 15. The first and rear ends are respectively pressed by the first sliding sleeve 34 and the first rear pressure cover 39, the first sliding sleeve 34 and the second front bearing 32 are clearance-centered, the front bearing seat 33 and the outer circle of the first sliding sleeve 34 are clearance-centered, the first rear pressure cover 39 is connected to the rear end of the first sliding sleeve 34 by screws, and a plurality of fourth angular locating pins 74 are connected between the first sliding sleeve 34 and the first rear pressure cover 39. The first spacer sleeve 30 is clamped between the inner ring of the first front bearing 31 and the inner ring of the second front bearing 32, and the first spacer sleeve 30 is clearance-matched with the outer circle of the main shaft 1. The cooling sleeve 36 is provided On the outside of the first spacer 30, the front end of the inner ring of the first front bearing 31 is pressed by the inner pressure cover 18, and the inner pressure cover 18 is fixed to the front end of the main shaft 1 by threads. The front and rear ends of the outer ring of the first front bearing 31 are pressed by the outer pressure cover 19 and the front bearing seat 33 respectively, and the outer pressure cover 19 is fixed to the front bearing seat 33 by screws. A plurality of third angular locating pins 73 are connected between the outer pressure cover 19 and the front bearing seat 33. The front end of the outer pressure cover 19 is pressed by the front end cover 10, and the front end cover 10 is fixed to the outer pressure cover 19 by screws. The outer pressure cover 19 is fixed to the front bearing seat 33 by screws. 3. The front end surface of the inner ring of the first rear bearing 41 contacts the second step shoulder 16. A second spacer sleeve 46 is tightly arranged between the inner ring of the first rear bearing 41 and the inner ring of the second rear bearing 42. The second spacer sleeve 46 is clearance-matched with the outer circle of the main shaft 1. The rear end of the inner ring of the second rear bearing 42 is pressed by the second rear pressure cover 47. The second rear pressure cover 47 is fixed to the rear end of the main shaft 1 and is centeringly matched with the outer circle of the main shaft 1. The rear bearing seat 43 is centeringly matched with the outer circle of the second sliding sleeve 44. A plurality of fifth angular locating pins 75 are connected between the second sliding sleeve 44 and the rear bearing seat 43.

[0026] In this embodiment, a first labyrinth gap 51 is provided between the front end cover 10, the outer pressure cover 19 and the inner pressure cover 18, a second labyrinth gap 52 is provided between the outer pressure cover 19 and the inner pressure cover 18, the front end of the second labyrinth gap 52 is communicated with the radial middle part of the first labyrinth gap 51, the rear end of the second labyrinth gap 52 is directly opposite to the front side of the first front bearing 31, the radial outer edge of the first labyrinth gap 51 is connected with the first reflow groove 53, the radial inner edge of the first labyrinth gap 51 is connected with the second reflow groove 54, the second reflow groove 54 is communicated with the outside atmosphere, a nose end air seal channel 191 is provided in the outer pressure cover 19, one end of the nose end air seal channel 191 is communicated with the second labyrinth gap 52, and the other end of the nose end air seal channel 191 is communicated with the external air source. The inner pressure cover 18 is fixed to the main shaft 1, and both belong to the rotating parts, and the front end cover 10, the outer pressure cover 19, and the front bearing seat 33 are fixed as non-rotating parts. A gap must be left between the rotating part and the non-rotating part. Therefore, the present invention designs a spindle nose end air sealing structure with a reflux groove at this gap. The speed at which the cutting fluid invades the spindle 1 is reduced through the first reflux groove 53 and the second reflux groove 54. At the same time, an external air source introduces positive pressure into the interior of the spindle 1 through the nose end air sealing channel 191 to supplement the vacuum area generated when the spindle 1 rotates at high speed. The pressurized gas introduced into the nose end air sealing channel 191 eventually passes through the second reflux groove 54 to the outside of the spindle, preventing external impurities from entering the interior of the spindle 1, thereby ensuring the airtightness, reliability and stability of the spindle 1.

[0027] In this embodiment, a plurality of first oil-gas lubrication branches 38 are connected to the external air extraction mechanism, a plurality of second oil-gas lubrication branches 45 are connected to the external air extraction mechanism, the first oil-gas lubrication branch 38 on the front side of the first front bearing 31 is opened in the outer pressure cover 19, the first oil-gas lubrication branch 38 on the rear side of the first front bearing 31 is opened in the front bearing seat 33, the first oil-gas lubrication branch 38 on the front side of the second front bearing 32 is opened in the first sliding sleeve 34, the first oil-gas lubrication branch 38 on the rear side of the second front bearing 32 is opened in the first rear pressure cover 39, the second oil-gas lubrication branch 45 on the front side of the first rear bearing 41 is opened in the rear bearing seat 43, and the second oil-gas lubrication branch 45 on the rear side of the first rear bearing 41 is opened in the rear bearing seat 43. The branch 45, the second oil-gas lubrication branch 45 on the front side of the second rear bearing 42, and the second oil-gas lubrication branch 45 on the rear side of the second rear bearing 42 are all opened in the second sliding sleeve 44. In a specific implementation scheme, an outer sleeve 48 is arranged on the outer side of the second sleeve 46, and the outer sleeve 48 is provided with interconnected radial guide grooves 49 and axial guide grooves 40. The front and rear ends of the axial guide grooves 40 are respectively opposite to the rear side of the first rear bearing 41 and the front side of the second rear bearing 42. The second oil-gas lubrication branch 45 on the rear side of the first rear bearing 41 and the second oil-gas lubrication branch 45 on the front side of the second rear bearing 42 are merged into a common branch 401, and the common branch 401 is connected to the radial guide groove 49.

[0028] In this embodiment, the knife-beating cylinder unit includes a knife-beating cylinder 6, a hollow knife-pulling rod 61, a knife-pulling claw 62 and a knife-releasing spring 63. Four connecting rods 64 are fixed to the front end of the piston of the knife-beating cylinder 6. The four connecting rods 64 pass through the second rear pressure cover 47 to be connected with the knife-pulling rod 61. The knife-pulling rod 61 is arranged on the inner side of the main shaft 1. A limiting boss 65 is radially arranged at the rear end of the knife-pulling rod 61. The inner circle of the front section of the main shaft 1 is provided with a third step shoulder 17. The front and rear centering of the front end of the knife-pulling rod 61 is matched with a transition sleeve 66 and a spring spacer sleeve 67. The transition sleeve 66 is matched with the inner circle of the main shaft 1 for centering. A radial through hole 68 is opened in the transition sleeve 66. The front of the main shaft 1 A cone handle blowing hole 69 is opened at the end, and the relative displacement between the transition sleeve 66 and the broaching rod 61 is controlled to form an air path switching structure for cone handle blowing, so that an air seal is formed between the tool 82 and the cone hole of the spindle 1. Specifically, when the spindle 1 is performing a tool loosening action, the piston of the tool-beating cylinder 6 moves, driving the broaching rod 61 to move. After the broaching rod 61 moves to the front end of the spindle 1, the radial through hole 68 is connected with the cone handle blowing hole 69. At this time, the pressurized gas introduced from the external air source will pass along the air path to between the front end cone hole of the spindle 1 and the tool 82, blowing away the chips remaining between the tool 82 and the spindle 1 during the processing, and preventing the chips from entering the spindle 1 The tapered hole scratches the spindle 1 and affects the machining accuracy of the spindle 1; the front end face of the spring spacer 67 contacts the third step shoulder 17, the clamping knife spring 63 is sleeved on the broaching rod 61, the rear end of the clamping knife spring 63 contacts the front end face of the limiting boss 65, and the front end of the clamping knife spring 63 contacts the rear end face of the spring spacer 67; the front end of the broaching rod 61 is threadedly connected to the limiting nut 60, the limiting nut 60 is located between the transition sleeve 66 and the spring spacer 67, and a gap is reserved between the rear end face of the limiting nut 60 and the front end face of the spring spacer 67, and the limiting nut 60 is used to limit the length of the clamping knife spring 63 in a free state, so that the clamping knife The spring 63 maintains a relatively short free length; the broaching claw 62 is threadedly connected to the front end of the broaching rod 61, and the front end of the broaching claw 62 is used to install the tool 82. The rear end of the knife-beating cylinder 6 is installed with a central water outlet rotating joint 81, and the middle part of the second rear pressure cover 47 is integrally provided with a central water outlet connecting pipe 471. The rear end of the central water outlet connecting pipe 471 is sealed and connected to the water outlet of the central water outlet rotating joint 81, and the front end of the central water outlet connecting pipe 471 is communicated with the inner hole of the broaching rod 61. The cooling water enters the central water outlet connecting pipe 471 through the central water outlet rotating joint 81, enters the inner hole of the broaching rod 61, and finally enters the cooling port of the tool 82.

[0029] During the operation of the main shaft 1, a plurality of cooling pipes 14 connect the first cooling ring groove 37 with the second cooling ring groove 13 to form a water-cooled circulating cooling circuit, which can effectively absorb the heat of the first front bearing 31 and the second front bearing 32 which generate relatively large amounts of heat when the main shaft 1 is operating, as well as the heat of the motor stator 21, control the heating of the bearings, and alleviate the temperature rise problem of the main shaft 1 bearings to a great extent, thereby extending the bearing life and improving the parts processing efficiency and processing accuracy. At the same time, based on the good cooling effect of the water-cooled circulation cooling circuit formed by the first cooling ring groove 37, the plurality of cooling pipes 14 and the second cooling ring groove 13, the plurality of first oil-gas lubrication branches 38 and the plurality of second oil-gas lubrication branches 45 can smoothly discharge the oil and gas in the first front bearing 31, the second front bearing 32, the first rear bearing 41 and the second rear bearing 42, and take away the heat of the first front bearing 31, the second front bearing 32, the first rear bearing 41 and the second rear bearing 42, thereby avoiding abnormal temperature rise due to excessive oil accumulation in the bearing raceway, thereby further enhancing the bearing cooling effect and ensuring the performance and life of the first front bearing 31, the second front bearing 32, the first rear bearing 41 and the second rear bearing 42 under high speed and high load conditions.

Claims

1. A spindle for a CNC machine tool, comprising a hollow spindle, a spindle sleeve, a motor, a first front bearing, a second front bearing, a first rear bearing, a second rear bearing and a knife-beating cylinder unit, wherein the first front bearing and the second front bearing are installed at a front section of the spindle at a front-to-back interval, the first rear bearing and the second rear bearing are installed at a front-to-back interval on the rear section of the spindle, a front bearing seat is installed on the outer side of the first front bearing and the second front bearing, a rear bearing seat is installed on the outer side of the first rear bearing and the second rear bearing, a first sliding sleeve is fixed on the outer side of the second front bearing, and the first sliding sleeve is fixed on the outer side of the second front bearing. The front end surface of the sleeve contacts the front bearing seat, and the outer sides of the first rear bearing and the second rear bearing are fixed with a second sliding sleeve. The motor is installed in the middle and rear section of the main shaft. The motor includes a stator and a rotor. The rotor is connected to the outer side of the main shaft by interference fit. The main shaft sleeve is connected to the outer side of the stator by interference fit. The front end and rear end of the main shaft sleeve are respectively connected to the front bearing seat and the rear bearing seat for centering. The knife-beating cylinder unit is arranged on the rear side of the main shaft. The knife-beating cylinder unit is used to realize the knife loosening and clamping function of the main shaft, and is characterized in that: A plurality of preload springs are evenly arranged between the front end surface of the first sliding sleeve and the front bearing seat, a cooling sleeve is centrally connected to the inner side of the front bearing seat, the cooling sleeve is arranged between the first front bearing and the second front bearing, a motor heat insulation sleeve is centrally connected to the inner side of the main shaft sleeve, the motor heat insulation sleeve is arranged on the outer side of the main shaft and located on the front side of the motor, a first cooling ring groove is arranged on the outer wall of the cooling sleeve, a second cooling ring groove is arranged on the outer wall of the motor heat insulation sleeve, the first cooling ring groove and the second cooling ring groove are connected through a plurality of cooling pipelines, the plurality of cooling pipelines are opened in the front bearing seat and the main shaft sleeve, the plurality of cooling pipelines are connected to an external cooling water supply mechanism, a plurality of first oil-gas lubrication branches are respectively arranged on the front and rear sides of each of the first front bearing and each of the second front bearing, a plurality of second oil-gas lubrication branches are respectively arranged on the front and rear sides of each of the first rear bearing and each of the second rear bearing, the plurality of first oil-gas lubrication branches and the plurality of second oil-gas lubrication branches are both connected to an external air extraction mechanism; The first front bearing, the second front bearing, the first rear bearing and the second rear bearing are respectively interference fit with the outer circle of the main shaft, the outer circles of the front section and the rear section of the main shaft are respectively provided with a first step shoulder and a second step shoulder, the rear end face of the inner ring of the second front bearing contacts with the first step shoulder, the front end and the rear end of the outer ring of the second front bearing are respectively pressed by the first sliding sleeve and the first rear pressure cover, the first sliding sleeve and the second front bearing are clearance-centered fit, the front bearing seat and the outer circle of the first sliding sleeve are clearance-centered fit, the first rear pressure cover is centeringly connected to the rear end of the first sliding sleeve, a first spacer is tightly arranged between the inner ring of the first front bearing and the inner ring of the second front bearing, the first spacer is clearance-matched with the outer circle of the main shaft, the cooling sleeve is arranged on the outside of the first spacer, the The front end of the inner ring of the first front bearing is pressed by the inner pressure cover, and the inner pressure cover is fixed to the front end of the main shaft by threads, and the front end and rear end of the outer ring of the first front bearing are pressed by the outer pressure cover and the front bearing seat respectively, and the outer pressure cover is fixed to the front bearing seat, and the front end of the outer pressure cover is pressed by the front end cover, and the front end cover and the outer pressure cover are fixedly connected to the front bearing seat, and the front end surface of the inner ring of the first rear bearing is in contact with the second step shoulder, and a second spacer is pressed between the inner ring of the first rear bearing and the inner ring of the second rear bearing, and the second spacer is clearance-matched with the outer circle of the main shaft, and the rear end of the inner ring of the second rear bearing is pressed by the second rear pressure cover, and the second rear pressure cover is fixed to the rear end of the main shaft and is centeringly matched with the outer circle of the main shaft, and the rear bearing seat is centeringly matched with the outer circle of the second sliding sleeve; The plurality of first oil-gas lubrication branches are connected to an external air extraction mechanism, and the plurality of second oil-gas lubrication branches are connected to an external air extraction mechanism. The first oil-gas lubrication branch on the front side of the first front bearing is arranged in the external pressure cover, the first oil-gas lubrication branch on the rear side of the first front bearing is arranged in the front bearing seat, the first oil-gas lubrication branch on the front side of the second front bearing is arranged in the first sliding sleeve, the first oil-gas lubrication branch on the rear side of the second front bearing is arranged in the first rear pressure cover, the second oil-gas lubrication branch on the front side of the first rear bearing is arranged in the rear bearing seat, the second oil-gas lubrication branch on the rear side of the first rear bearing, the second oil-gas lubrication branch on the front side of the second rear bearing, and the second oil-gas lubrication branch on the rear side of the second rear bearing are all arranged in the second sliding sleeve.

2. A CNC machine tool spindle according to claim 1, characterized in that: A plurality of first angular locating pins are connected between the cooling sleeve and the front bearing seat, a plurality of second angular locating pins are connected between the motor heat insulation sleeve and the main shaft sleeve, a plurality of third angular locating pins are connected between the outer pressure cover and the front bearing seat, a plurality of fourth angular locating pins are connected between the first sliding sleeve and the first rear pressure cover, and a plurality of fifth angular locating pins are connected between the second sliding sleeve and the rear bearing seat.

3. A CNC machine tool spindle according to claim 1, characterized in that: A first labyrinth gap is provided between the front end cover, the outer pressure cover and the inner pressure cover, a second labyrinth gap is provided between the outer pressure cover and the inner pressure cover, the front end of the second labyrinth gap is communicated with the radial middle part of the first labyrinth gap, the rear end of the second labyrinth gap is opposite to the front side of the first front bearing, the radial outer edge of the first labyrinth gap is connected with a first reflow groove, the radial inner edge of the first labyrinth gap is connected with a second reflow groove, the second reflow groove is communicated with the outside atmosphere, a nose end air seal channel is opened in the outer pressure cover, one end of the nose end air seal channel is communicated with the second labyrinth gap, and the other end of the nose end air seal channel is communicated with an external air source.

4. A CNC machine tool spindle according to claim 1, characterized in that: An outer spacer is arranged on the outer side of the second spacer, and a radial guide groove and an axial guide groove which are connected to each other are opened in the outer spacer, and the front end and the rear end of the axial guide groove are respectively opposite to the rear side of the first rear bearing and the front side of the second rear bearing, and the second oil and gas lubrication branch on the rear side of the first rear bearing and the second oil and gas lubrication branch on the front side of the second rear bearing are merged into a common branch, and the common branch is connected to the radial guide groove.

5. The CNC machine tool spindle according to claim 1, characterized in that: The knife beating cylinder unit includes a knife beating cylinder, a knife pulling rod, a knife pulling claw and a knife loosening spring. A plurality of connecting rods are fixed to the front end of the piston of the knife beating cylinder. The plurality of connecting rods pass through the second rear pressure cover and are connected to the knife pulling rod. The knife pulling rod is arranged on the inner side of the spindle. A limiting boss is radially provided at the rear end of the knife pulling rod. The inner circle of the front section of the spindle is provided with a third step shoulder. A transition sleeve and a spring spacer are provided for the front and rear centering of the front end of the knife pulling rod. The transition sleeve is matched with the inner circle of the spindle for centering. A radial through hole is provided in the transition sleeve. A conical handle blowing hole is provided at the front end of the spindle. When the spindle performs the knife loosening action, the knife pulling rod moves toward the spindle. After the front end of the shaft moves into place, the radial through hole is connected with the blowing hole of the tapered handle, the front end face of the spring spacer is in contact with the shoulder of the third step, the loosening knife spring sleeve is arranged on the broaching rod, the rear end of the loosening knife spring is in contact with the front end face of the limiting boss, the front end of the loosening knife spring is in contact with the rear end face of the spring spacer, the front end of the broaching rod is threadedly connected with a limiting nut, the limiting nut is located between the transition sleeve and the spring spacer, a gap is reserved between the rear end face of the limiting nut and the front end face of the spring spacer, the broaching claw is threadedly connected with the front end of the broaching rod, and the front end of the broaching claw is used for installing the tool.

6. A CNC machine tool spindle according to claim 5, characterized in that: The knife pulling rod is a hollow knife pulling rod, and a central water outlet rotating joint is installed at the rear end of the knife hitting cylinder. A central water outlet connecting pipe is integrally provided in the middle part of the second rear pressure cover. The rear end of the central water outlet connecting pipe is sealed and connected to the water outlet of the central water outlet rotating joint, and the front end of the central water outlet connecting pipe is communicated with the inner hole of the knife pulling rod.

Images