Electric spindle and numerical control machine tool

Abstract

The utility model relates to the field of working spindles, in particular to an electric spindle and a numerical control machine tool. The motorized spindle and the numerical control machine tool are used for solving the problems that the rotating speed of a motorized spindle in the prior art needs to be monitored through external monitoring equipment during use, and the monitoring precision is low. The electric spindle comprises a shell and a spindle, a stator is mounted in the shell, a front bearing seat and a rear bearing seat are mounted in front of and behind the stator respectively, the rear bearing seat is movably mounted in the shell, a front bearing and a rear bearing are mounted in the front bearing seat and the rear bearing seat respectively, and a spring seat is mounted on the rear portion of the rear bearing seat and provided with a spring. A hollow containing cavity is defined by the rear bearing seat and the wall face of the spring seat, the rear end of the main shaft extends into the containing cavity, an encoder used for monitoring the rotating state of the main shaft is installed in the containing cavity, and an encoder lead backwards penetrates through the spring seat and the rear cover to be led out. Therefore, the encoder can directly monitor the rotating position and the rotating speed of the main shaft in the electric main shaft, and the monitoring precision of the main shaft is improved.

Description

Technical Field

[0001] This utility model relates to the field of spindles, specifically to an electric spindle and a CNC machine tool. Background Technology

[0002] High-speed electric spindles integrate the functions of a motor and a spindle, eliminating the traditional power system driven by belts or gears. This simplifies the mechanical structure, reduces energy loss, and improves the rigidity and reliability of the system. They can operate stably at extremely high speeds (typically tens of thousands of revolutions per minute), significantly improving processing speed and surface quality.

[0003] Chinese invention patent application CN106735335A discloses a high-speed electric spindle with precise oil supply and air lubrication. The electric spindle includes a housing and a spindle. A rear cover is installed at the rear end of the housing. A stator is fixedly installed inside the housing. A front bearing seat is installed in front of the stator, and a rear bearing seat is installed behind the stator. The rear bearing seat is slidably installed in the housing via a sliding bearing. Front and rear bearings for rotating and supporting the spindle are installed in the front and rear bearing seats. A spring seat is located at the rear end of the rear bearing seat, and a spring is installed between the rear bearing seat and the spring seat to provide preload force to the rear bearing. After installation, the walls of the rear bearing seat and the spring seat form a hollow cavity, into which the rear end of the spindle extends. The electric spindle operates at extremely high speeds, but it lacks a monitoring device for the spindle's rotational speed and position. During use, its rotational speed needs to be monitored by external monitoring equipment, which has low monitoring accuracy. Utility Model Content

[0004] The purpose of this invention is to provide an electric spindle that solves the problem of low accuracy in monitoring the spindle speed of existing electric spindles, which require external monitoring equipment. Another purpose of this invention is to provide a CNC machine tool that solves the problem of low accuracy in monitoring the spindle speed of existing CNC machine tools, which also require external monitoring equipment.

[0005] To solve the above-mentioned technical problems, the electric spindle of this utility model adopts the following technical solution:

[0006] An electric spindle includes a housing and a spindle. A rear cover is installed at the rear end of the housing. A stator is fixedly installed inside the housing. A front bearing housing is installed in front of the stator, and a rear bearing housing is installed behind the stator. The rear bearing housing is movably installed in the housing in a front-rear direction. Front and rear bearings for rotatably supporting the spindle are respectively installed in the front and rear bearing housings. A spring seat is installed at the rear of the rear bearing housing. The spring seat is equipped with a spring to provide preload force to the rear bearing. After the rear bearing housing and the spring seat are installed, their walls form a hollow receiving cavity. The rear end of the spindle extends into the receiving cavity. An encoder for monitoring the rotation state of the spindle is installed in the receiving cavity. The encoder lead passes through the spring seat and the rear cover in sequence and exits.

[0007] Furthermore, the rear bearing housing includes an end face portion and a rearwardly extending cylindrical body portion, the end face portion being provided with a mounting groove for mounting the rear bearing, the rear bearing being mounted in the mounting groove.

[0008] Furthermore, a protruding ring is provided on the front side of the end face portion, and the mounting groove is provided on the inner side of the protruding ring.

[0009] Furthermore, the inner wall of the cylindrical part of the rear bearing housing is provided with a receiving groove that opens towards the inner cavity of the receiving cavity. The fixed part of the encoder is installed in the receiving groove, and the rotating part is installed on the main shaft.

[0010] Furthermore, each of the front and rear bearings is provided in a single configuration, and the front and rear bearings are paired together.

[0011] Furthermore, the front and rear bearings are installed face-to-face.

[0012] Furthermore, both the spring seat and the rear cover are provided with encoder lead wire exit channels, which are set independently of the stator lead wire exit channels.

[0013] Furthermore, one of the rear cover and the rear bearing housing is provided with a guide pin, and the other is provided with a guide hole. The rear bearing housing and the rear cover are guided and fitted in the axial direction through the guide pin and the guide hole.

[0014] Furthermore, the spring is disposed between the spring seat and the rear cover to provide a forward clamping force to the spring seat.

[0015] This invention proposes an improved technical solution by installing an encoder for monitoring the spindle's rotational state within the housing cavity. In this way, the encoder can directly monitor the spindle's rotational position and speed inside the electric spindle, improving the accuracy of spindle speed monitoring and avoiding monitoring errors and signal delays caused by external monitoring. This effectively enhances the control accuracy and system response speed of the electric spindle. Furthermore, integrating the encoder inside the electric spindle results in high integration and a more compact structure.

[0016] Another aspect of this utility model provides a CNC machine tool, which includes an electric spindle. The electric spindle includes a housing and a spindle. A rear cover is installed at the rear end of the housing. A stator is fixedly installed inside the housing. A front bearing seat is installed in front of the stator, and a rear bearing seat is installed behind the stator. The rear bearing seat is movably installed in the housing in a front-rear direction. Front and rear bearings for rotating and supporting the spindle are respectively installed in the front and rear bearing seats. A spring seat is installed at the rear of the rear bearing seat. The spring seat is equipped with a spring to provide preload force to the rear bearing. After the rear bearing seat and the spring seat are installed, their walls form a hollow cavity. The rear end of the spindle extends into the cavity. An encoder for monitoring the spindle rotation state is installed in the cavity. The encoder lead passes through the spring seat and the rear cover in sequence and exits.

[0017] Furthermore, the rear bearing housing includes an end face portion and a rearwardly extending cylindrical body portion, the end face portion being provided with a mounting groove for mounting the rear bearing, the rear bearing being mounted in the mounting groove.

[0018] Furthermore, a protruding ring is provided on the front side of the end face portion, and the mounting groove is provided on the inner side of the protruding ring.

[0019] Furthermore, the inner wall of the cylindrical part of the rear bearing housing is provided with a receiving groove that opens towards the inner cavity of the receiving cavity. The fixed part of the encoder is installed in the receiving groove, and the rotating part is installed on the main shaft.

[0020] Furthermore, each of the front and rear bearings is provided in a single configuration, and the front and rear bearings are paired together.

[0021] Furthermore, the front and rear bearings are installed face-to-face.

[0022] Furthermore, both the spring seat and the rear cover are provided with encoder lead wire exit channels, which are set independently of the stator lead wire exit channels.

[0023] Furthermore, one of the rear cover and the rear bearing housing is provided with a guide pin, and the other is provided with a guide hole. The rear bearing housing and the rear cover are guided and fitted in the axial direction through the guide pin and the guide hole.

[0024] Furthermore, the spring is disposed between the spring seat and the rear cover to provide a forward clamping force to the spring seat.

[0025] This invention proposes an improved technical solution by installing an encoder for monitoring the spindle's rotational state within the housing cavity. In this way, the encoder can directly monitor the spindle's rotational position and speed inside the electric spindle, improving the accuracy of spindle speed monitoring and avoiding monitoring errors and signal delays caused by external monitoring. This effectively enhances the control accuracy and system response speed of the CNC machine tool's electric spindle. Furthermore, integrating the encoder inside the electric spindle results in high integration and a more compact structure. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the rear end face of an electric spindle according to the present invention;

[0027] Figure 2 For electric spindle in Figure 1 A cross-sectional view of surface AA;

[0028] Figure 3 for Figure 2 A magnified view of a portion of point A in the middle;

[0029] Figure 4 A schematic diagram showing the structure through which the motor leads and encoder signal lines pass through the back cover;

[0030] Figure 5 This is a front view of the spring seat;

[0031] Figure 6 for Figure 5 A cross-sectional view on the BB side;

[0032] Figure 7 This is a front view of the rear bearing housing;

[0033] Figure 8 for Figure 7 Sectional view on the C-plane.

[0034] In the diagram: 1. Main shaft; 2. Front bearing; 3. Front bearing housing; 4. Housing; 5. Stator; 6. Rotor; 7. Rear bearing; 8. Sliding bearing; 9. Rear bearing housing; 91. End face; 911. Convex ring; 92. Cylinder body; 921. Receiving groove; 10. Encoder reading head; 11. Rear cover; 12. Rear pressure cap; 13. Encoder gear plate; 14. Spring; 15. Spring seat; 16. Stator lead wire; 17. Encoder lead wire; 18. Encoder lead wire exit channel; 19. Stator lead wire exit channel. Detailed Implementation

[0035] This invention addresses the problems existing in the above-mentioned technical solutions by proposing an improved technical solution. The core concept of this invention is to install an encoder for monitoring the spindle rotation state within the receiving cavity. In this way, the encoder can directly monitor the spindle's rotational position and speed inside the electric spindle, improving the monitoring accuracy of the spindle speed and avoiding monitoring errors and signal delays caused by external monitoring. This effectively improves the control accuracy and system response speed of the CNC machine tool's electric spindle. Furthermore, integrating the encoder inside the electric spindle results in high integration and a more compact structure.

[0036] Based on the above-described inventive concept, an electric spindle of this utility model includes as follows: Figure 2The housing 4 and main shaft 1 are shown. A rear cover 11 is installed at the rear end of the housing 4. A stator 5 is fixedly installed inside the housing 4. A front bearing seat 3 is installed in front of the stator 5, and a rear bearing seat 9 is installed behind the stator 5. The rear bearing seat 9 is movably installed inside the housing 4 in a front-rear direction. In this embodiment, the rear bearing seat 9 is installed inside the housing 4 by a sliding bearing 8 so that the rear bearing seat 9 can move relatively backward to compensate for the elongation of the main shaft 1 when the main shaft 1 rotates at high speed and undergoes thermal expansion. Front and rear bearings for rotatably supporting the main shaft are respectively installed in the front and rear bearing seats 9. A rotor 6 is also provided on the main shaft corresponding to the position of the stator 5. A spring seat 15 is installed at the rear of the rear bearing seat 9. The spring seat 15 is equipped with a spring 14 to provide preload force to the rear bearing 7. After the rear bearing seat 9 and the spring seat 15 are installed, their walls form a hollow receiving cavity. The rear end of the main shaft 1 extends into the receiving cavity. The receiving cavity is equipped with a bearing seat 14, and a bearing seat 15 is installed in the housing 4. Figure 2 , Figure 3 The encoder shown is used to monitor the rotational state of the spindle 1. The encoder lead 17 passes backward through the spring seat 15 and the rear cover 11 in sequence. The encoder lead 17 passes through... Figure 1 The rear cover 11 shown is connected to the signal plug at the rear end of the rear cover 11. The encoder can directly monitor the rotational position and speed of the spindle 1 inside the electric spindle, which improves the monitoring accuracy of the spindle 1, avoids monitoring errors and signal delays caused by external monitoring, and effectively improves the control accuracy of the electric spindle and the system response speed.

[0037] In this embodiment, the rear bearing housing 9 includes as follows: Figure 8 The end face portion 91 and the rearwardly extending cylindrical body portion 92 are shown. The cylindrical body portion 92 has a certain axial length, and the rear bearing seat 9 is guided and movably mounted to the housing 4 through its cylindrical body portion 92. The spring seat 15 in this embodiment is as follows... Figure 6The diagram shows a plate-like structure, with the cylindrical body 92 of the rear bearing housing 9 and the plate-like spring seat 15 forming the receiving cavity. A mounting groove for installing the rear bearing 7 is provided on the end face 91, and the rear bearing 7 is installed within the mounting groove. If the rear bearing 7 is installed within the cylindrical body 92 of the rear bearing housing 9, the end face 91 of the rear bearing housing 9 will occupy a certain axial length of the spindle 1, and a pressure member also needs to be installed at the rear of the rear bearing 9. This necessitates increasing the axial dimension of the spindle 1 to accommodate the bearing and pressure member. A larger axial dimension reduces the rigidity of the spindle 1, increasing vibration and thermal deformation during use, thus affecting the machining effect and efficiency of the electric spindle. Therefore, in this invention, the rear bearing 7 is mounted on the end face portion 91 of the rear bearing housing 9. The spring 14 at the rear of the spring seat 15 can apply a certain preload to the rear bearing 7. The interior of the cylindrical body portion 92 can also be directly used to mount the encoder, saving the axial length occupied by the rear bearing 7 and the encoder on the spindle 1. In this way, the length of the spindle 1 can be shortened to improve the rigidity of the spindle 1, so that the spindle 1 can more effectively resist the cutting forces, vibrations and deformations generated during machining. In addition, in other embodiments, the rear bearing can also be set in the cylindrical body portion of the rear bearing housing, and the encoder can be mounted at the rear of the rear bearing.

[0038] In this embodiment, a convex ring 911 is provided on the front side of the end face portion 91, and the mounting groove is provided on the inner surface of the convex ring 911. The convex ring 911 shortens the distance between the front and rear bearings, which can further reduce the axial dimension of the spindle 1. This is especially important for machine tools with a compact layout. Reducing the axial dimension of the spindle 1 can improve the rigidity of the spindle 1, so that the spindle 1 can more effectively resist the cutting forces, vibrations, and deformations generated during machining. In addition, in other embodiments, the convex ring may not be provided in front of the end face portion, the thickness of the end face portion may be increased to a certain extent, and the mounting groove may be directly provided on the inner circumferential surface of the end face portion.

[0039] In this embodiment, as Figure 7 , Figure 8 As shown, the inner wall of the cylindrical portion 92 of the rear bearing housing 9 is provided with a receiving groove 921 that opens towards the inner cavity of the receiving chamber. The fixed part of the encoder is installed in the receiving groove 921, and the rotating part is installed on the main shaft 1. The encoder in this embodiment is an incremental magnetic ring encoder. The shape of the receiving groove 921 is adapted to the shape of the fixed part of the encoder (encoder reading head 10), and the rotating part of the encoder (encoder gear disk 13) is installed on the main shaft 1 through the rear pressure cap 12. By providing the receiving groove 921, the installation of the encoder reading head 10 is facilitated, and the positioning of the encoder reading head 10 is also convenient. In addition, in other embodiments, the receiving groove 921 may not be provided, and the fixed part of the encoder may be directly fixedly installed in the rear bearing housing 9.

[0040] In this embodiment, one front and one rear bearing are provided, and the front and rear bearings are paired. If multiple front and rear bearings are provided, the length of the main shaft 1 needs to be increased to accommodate the installation of multiple bearings. Therefore, in this embodiment, one front and one rear bearing are provided, and the front and rear bearings are paired, which ensures the bearing load capacity and also reduces the axial dimension of the main shaft 1. In addition, in other embodiments, the front and rear bearings can be paired, with the front bearings paired and the rear bearings paired. In this embodiment, the front and rear bearings are angular contact ball bearings. Of course, in other embodiments, the front and rear bearings can also be tapered roller bearings, and the front and rear bearings can be paired.

[0041] In this embodiment, the front and rear bearings are installed face-to-face. Face-to-face installation of the front and rear bearings forms a stable support structure and ensures even pressure distribution between them, improving the bearing's load-bearing capacity. Simultaneously, the face-to-face installation of the bearings is relatively compact, which increases the rigidity of the spindle 1 and more effectively resists cutting forces, vibrations, and deformations generated during machining, ensuring machining accuracy. Furthermore, in other embodiments, the front and rear bearings can also be installed back-to-back.

[0042] In this embodiment, as Figure 4 , Figure 5 As shown, both the spring seat 15 and the rear cover 11 are provided with encoder lead wire exit channels 18, which are set independently of the stator lead wire exit channels 19. The stator lead 16 has a high voltage rating; if the encoder lead 17 and the stator lead 16 use the same exit channel, the stator lead 16 may interfere with the encoder lead 17. Therefore, in this embodiment, the encoder lead wire exit channel 18 is set independently of the stator lead wire exit channel 19, ensuring that the two exit wires do not interfere with each other. Furthermore, in other embodiments, the spring seat 15 and the rear cover 11 may also have only one exit channel, with the encoder lead and stator lead wire passing through the same exit channel, and good shielding provided between them.

[0043] In this embodiment, one of the rear cover 11 and the rear bearing seat 9 is provided with a guide pin, and the other is provided with a guide hole. The rear cover 11 and the rear bearing seat 9 are guided and engaged axially through the guide pin and the guide hole. This ensures the stability of the rear bearing seat 9 during its forward and backward movement.

[0044] In this embodiment, the spring 14 is disposed between the spring seat 15 and the rear cover 11 to provide a forward clamping force to the spring seat 15. The spring 14 is a compression spring, and the rear bearing seat 9 is movably mounted in the housing 4 in the front-rear direction. When the rear bearing seat 9 moves backward, the compression spring located between the spring seat 15 and the rear cover 11 can apply a forward force to the spring seat 15. At this time, the spring seat 15 can pre-tighten the rear bearing 7 located in the front convex ring 911 of the rear bearing seat 9, ensuring the reliability of the rotational support of the rear bearing 7. In addition, in other embodiments, the connection relationship of the rear bearing seat, the rear bearing, the spring seat, and the rear cover can also be consistent with the connection relationship in the oil-air lubricated high-speed main electric spindle of application publication number CN106735335A. In this case, the spring can be disposed between the rear bearing seat 9 and the spring seat 15.

[0045] Another aspect of this utility model provides a CNC machine tool, which includes an electric spindle. Since the electric spindle is the same as the embodiment of the electric spindle described above, it will not be described again here.

[0046] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. The patent protection scope of the present utility model shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present utility model shall also be included within the protection scope of the present utility model.

Claims

1. An electric spindle, comprising a housing and a spindle, a rear cover mounted on the rear end of the housing, a stator fixedly mounted inside the housing, a front bearing housing mounted in front of the stator, and a rear bearing housing mounted behind the stator, the rear bearing housing being movably mounted in the housing in a front-rear direction, front and rear bearings for rotatably supporting the spindle being respectively mounted in the front and rear bearing housings, a spring seat mounted on the rear part of the rear bearing housing, the spring seat being equipped with a spring to provide preload force to the rear bearing, the rear bearing housing and the spring seat, after installation, their walls form a hollow receiving cavity, the rear end of the spindle extending into the receiving cavity, characterized in that: An encoder for monitoring the spindle rotation is installed inside the cavity, and the encoder leads pass through the spring seat and the rear cover in sequence.

2. The electric spindle according to claim 1, characterized in that: The rear bearing housing includes an end face portion and a rearwardly extending cylindrical body portion. The end face portion is provided with a mounting groove for installing the rear bearing, and the rear bearing is installed in the mounting groove.

3. The electric spindle according to claim 2, characterized in that: A protruding ring is provided on the front side of the end face portion, and the mounting groove is provided on the inner side of the protruding ring.

4. The electric spindle according to claim 2, characterized in that: The inner wall of the cylindrical part of the rear bearing housing is provided with a receiving groove that opens towards the inner cavity of the receiving cavity. The fixed part of the encoder is installed in the receiving groove, and the rotating part is installed on the main shaft.

5. The electric spindle according to claim 3, characterized in that: Each of the front and rear bearings is provided, and the front and rear bearings are paired.

6. The electric spindle according to claim 5, characterized in that: The front and rear bearings are installed face-to-face.

7. The electric spindle according to any one of claims 1-6, characterized in that: Both the spring seat and the rear cover are equipped with encoder lead wire exit channels, which are set independently of the stator lead wire exit channels.

8. The electric spindle according to any one of claims 1-6, characterized in that: One of the rear cover and the rear bearing housing is provided with a guide pin, and the other is provided with a guide hole. The rear bearing housing and the rear cover are guided and fitted in the axial direction by the guide pin and the guide hole.

9. The electric spindle according to any one of claims 1-6, characterized in that: The spring is positioned between the spring seat and the rear cover to provide a forward clamping force to the spring seat.

10. A CNC machine tool, comprising an electric spindle, characterized in that: The electric spindle includes the electric spindle according to any one of claims 1-9.

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