High-speed motorized spindle integrating electromagnetic actuator and magnetofluid bearing and use method of high-speed motorized spindle

Abstract

The invention discloses a high-speed motorized spindle integrating an electromagnetic actuator and a magnetofluid bearing and a using method. The high-speed motorized spindle comprises a spindle body, and a spindle body of the spindle body is supported through the arranged magnetofluid bearing; an electromagnetic actuator system used for detecting and controlling fluttering of the main shaft is arranged at the end of the main shaft and comprises a displacement detection mechanism used for detecting fluttering displacement of the main shaft and an electromagnetic vibration suppression mechanism used for applying electromagnetic force to suppress fluttering of the main shaft according to the detection result of the displacement detection mechanism. According to the magnetofluid bearing, stable and high-rigidity support is provided for a shaft by using a magnetofluid medium and utilizing the characteristic that the viscosity of the magnetofluid can be changed under an external magnetic field; and meanwhile, the electromagnetic actuator actively controls vibration generated in the machining process through accurate magnetic field control, and the stability of the main shaft in the machining process can be effectively improved. Through the combination of the two, the overall stability and the dynamic response capability of the system are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-speed electric spindle vibration control, and particularly to a high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing and a usage method thereof. Background Art

[0002] A high-speed electric spindle is a new technology that integrates a machine tool spindle and a spindle motor. It eliminates the belt drive and gear drive of the traditional spindle, combining the spindle motor and the machine tool spindle into one. Compared with the traditional spindle, the high-speed electric spindle has a more compact structure, with the advantages of high rotational speed and high precision, meeting the requirements of high-speed cutting and precision machining. However, chatter is likely to occur during the high-speed cutting process, which will seriously affect the service life of the machine tool spindle parts and the surface quality of the machined parts. Therefore, it is necessary to suppress this phenomenon. For a high-speed electric spindle of a machine tool supported by a magnetic suspension bearing, the support stiffness and damping of this structure are controllable, and the active vibration suppression advantage of the active magnetic suspension bearing can be utilized for the active control of milling chatter. However, due to the relatively low radial support stiffness of the magnetic suspension bearing, this device is only applicable to the machining process with high speed and small radial force, and the existing spindle vibration displacement detection method has a low detection frequency and cannot effectively suppress micro-amplitude high-frequency vibration. Summary of the Invention

[0003] Technical Objectives: Aiming at the deficiencies of the existing high-speed electric spindle, the present invention discloses a high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing and a usage method thereof.

[0004] Technical Solutions: To achieve the above technical objectives, the present invention adopts the following technical solutions: A high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing, including a spindle, and the shaft body of the spindle is supported by a magnetic fluid bearing provided; an electromagnetic actuator system for detecting and controlling the spindle chatter is arranged at the end of the spindle. The electromagnetic actuator system includes a displacement detection mechanism for detecting the spindle chatter displacement and an electromagnetic vibration suppression mechanism for suppressing the spindle chatter by applying an electromagnetic force according to the detection result of the displacement detection mechanism. The electromagnetic vibration suppression mechanism includes an actuator mover iron core ring fixedly relative to the spindle and an actuator stator magnetic pole concentrically arranged on the outer periphery of the actuator mover iron core ring. The actuator stator magnetic pole applies a magnetic force to the actuator mover iron core ring to suppress the spindle chatter.

[0005] Preferably, the actuator stator magnetic pole of the present invention includes a stator main body and magnetic poles arranged radially along the stator main body. Actuator coils are wound around the magnetic poles to form control magnetic poles, and the electromagnetic force generated at the corresponding magnetic poles by energizing the actuator coils is used to suppress the spindle chatter.

[0006] Preferably, in the magnetic poles of the present invention, part of the magnetic poles are embedded with the actuator stator permanent magnets to form bias magnetic poles, and the spindle vibration is controlled through the cooperation of the bias magnetic poles and the control magnetic poles.

[0007] Preferably, along the circumferential direction of the stator body of the present invention, the control magnetic poles and the bias magnetic poles are arranged at intervals.

[0008] Preferably, the actuator stator permanent magnet of the present invention has a six-pole structure, among which, three poles are bias magnetic poles and three poles are control magnetic poles.

[0009] Preferably, the displacement detection mechanism of the present invention includes a sensor pressure plate concentrically arranged with the spindle. A displacement sensor for detecting the displacement of the spindle is embedded in the sensor pressure plate, and the displacement sensors are evenly distributed along the circumferential direction of the spindle.

[0010] Preferably, the displacement sensor of the present invention adopts an eddy current sensor. A sensor detection ring is arranged on the spindle, and the sensor detection ring is relatively fixed with the spindle and rotates synchronously with the spindle. The eddy current sensor detects the flutter displacement of the spindle by detecting the displacement of the sensor detection ring.

[0011] Preferably, the sensor detection ring of the present invention adopts a cast copper alloy material.

[0012] The present invention discloses a usage method based on the above high-speed electric spindle. The spindle is supported by the magnetic fluid bearings arranged at both ends, and the motor rotor arranged on the spindle is driven to rotate by the motor stator to drive the rotation of the spindle; during the operation of the spindle, the displacement detection mechanism acquires the flutter displacement direction and displacement distance of the spindle, and an electromagnetic vibration suppression mechanism applies an electromagnetic force to the spindle to suppress the spindle vibration.

[0013] Preferably, when suppressing the spindle flutter of the present invention, first, the magnetic force generated by the polarized magnetic poles of the electromagnetic vibration suppression mechanism is used to suppress the spindle flutter. When the spindle vibration exceeds the suppression range of the bias magnetic poles, the control magnetic poles are then energized, and the magnitude and direction of the electromagnetic force of the control magnetic poles are changed by using the current to actively suppress the spindle.

[0014] Beneficial effects: A high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing and a usage method disclosed by the present invention have the following beneficial effects: 1. The present invention supports the spindle through a magnetic fluid bearing. Since nano-sized magnetic particles are added to the magnetic fluid bearing, the friction with the bearing surface is low; moreover, the viscosity of the magnetic fluid is much greater than that of ordinary lubricating oil under the action of an external magnetic field. The change in the viscosity of the lubricant will significantly affect the pressure distribution of the fluid film bearing, thereby affecting the bearing capacity; in addition, by designing a suitable external magnetic field, the magnetic fluid can be maintained at the position where lubrication is required, enabling the magnetic fluid to have self-sealing while overcoming the effects of gravity and centrifugal force caused by shaft rotation, and keeping the state of the friction area stable. The combination of this dynamic and static support enables the entire spindle system to exhibit better performance in a high-speed and high-precision machining environment.

[0015] 2. The present invention sets an actuator mover core ring on the spindle. When suppressing spindle chatter, the electromagnetic force directly acts on the actuator mover core ring, which can efficiently transmit the magnetic force and ensure the effect of suppressing spindle vibration.

[0016] 3. The present invention forms a control magnetic force by winding coils around the magnetic poles, and can flexibly control the magnitude of the generated electromagnetic force by controlling the current. The offset magnetic poles embedded with the actuator stator magnetic steel can directly utilize the principle of the minimum magnetic resistance of the offset magnetic poles to suppress the vibration during the operation of the spindle when the vibration is small, without the need for additional current control.

[0017] 4. The actuator stator magnetic pole of the present invention has a six-pole structure, and controls the vibration during the operation of the spindle by combining the offset magnetic flux and the control magnetic flux, which can reduce power consumption, and the force can be decoupled in the radial direction, with simple control, and has the advantages of non-contact friction, long life, low power consumption, good linearity, low time delay, active suppression, etc., and has broad application prospects in the field of vibration control.

[0018] 5. The displacement detection mechanism of the present invention directly detects the radial displacement of the spindle end using an eddy current sensor and directly transmits it to the controller for vibration suppression, without the need for complex filtering and parameter calculation.

[0019] 6. The present invention sets a sensor detection ring on the spindle. The eddy current sensor directly detects the displacement of the copper ring, and uses the high conductivity of copper to increase the upper limit of the detection frequency to 20 kHz, which can capture the micro-amplitude high-frequency vibration easily overlooked by ordinary sensors, realize high-precision control of spindle vibration, and meet the high-precision machining requirements of the machine tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0021] Figure 1 It is a schematic diagram of the overall structure of the high-speed electric spindle of the present invention; Figure 2 Schematic structural diagram of the electromagnetic actuator system of the present invention; Figure 3 Schematic structural diagram of the stator pole of the actuator of the present invention; Figure 4 Schematic structural diagram of the magnetic fluid bearing of the present invention; Among them, 1 - main shaft, 2 - actuator rotor iron core ring, 3 - actuator stator pole, 4 - stator main body, 5 - pole, 6 - actuator coil, 7 - sensor pressure plate, 8 - displacement sensor, 9 - sensor detection ring, 10 - outer housing, 11 - motor rotor, 12 - motor stator, 13 - stator coil, 14 - angular contact ball bearing, 15 - angular contact bearing base, 16 - actuator housing, 17 - inner stator retaining ring, 18 - outer stator retaining ring, 19 - magnetic fluid bearing, 20 - bearing base, 21 - actuator stator magnet, 101 - upper shaft sleeve, 102 - upper end cover, 103 - semi-circular permanent magnet, 104 - lower shaft sleeve, 105 - lower end cover, 106 - magnetic isolation sheet. Detailed implementation manners

[0022] Now, reference will be made in detail to the embodiments of the present disclosure, one or more examples of which are set forth below. Each embodiment and example is provided by way of explanation of the apparatus, components, and materials of the present disclosure, and not by way of limitation. On the contrary, the following description provides a convenient illustration for implementing the exemplary embodiments of the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the teachings of the present disclosure without departing from the scope or spirit of the present disclosure.

[0023] As Figures 1 - 4 shown, the present invention discloses a high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing, including a main shaft 1, and the shaft body of the main shaft 1 is supported by a magnetic fluid bearing 19 provided; an electromagnetic actuator system for detecting and controlling the chatter of the main shaft is provided at the end of the main shaft 1, the electromagnetic actuator system includes a displacement detection mechanism for detecting the chatter displacement of the main shaft and an electromagnetic vibration suppression mechanism for suppressing the chatter of the main shaft by applying an electromagnetic force according to the detection result of the displacement detection mechanism, the electromagnetic vibration suppression mechanism includes an actuator rotor iron core ring 2 fixedly relative to the main shaft 1 and an actuator stator pole 3 concentrically arranged on the outer periphery of the actuator rotor iron core ring 2, both of which are made of silicon steel sheet material, and the actuator stator pole 3 applies a magnetic force to the actuator rotor iron core ring 2 to suppress the chatter of the main shaft.

[0024] An outer housing 10 is provided outside the main shaft 1, and the magnetic fluid bearing 19 and the electromagnetic actuator system are both provided on the outer housing 10, as Figure 1As shown in the figure, the magnetic fluid bearing 19 is arranged at the end positions near both ends of the main shaft 1, and is assembled through a bearing base 20 arranged inside the outer housing 10 to support the main shaft; a motor rotor 11 and a motor stator 12 for driving the main shaft 1 to rotate are arranged in the middle of the main shaft 1. The motor rotor 11 is fixed to the main shaft 1. A stator coil 13 is provided on the motor stator 12. Torque is provided by the stator coil 13 to drive the main shaft 1 to rotate at a high speed so that the main shaft 1 can be used for machine tool processing operations; an angular contact ball bearing 14 capable of withstanding a large axial force can also be arranged at the other end of the main shaft 1 away from the processing end. The angular contact ball bearing 14 is installed inside the outer housing 10 through an angular contact ball bearing base 15.

[0025] As Figure 4 shown, the magnetic fluid bearing structure provided by the present invention changes the viscosity and load-bearing capacity of the magnetic fluid through the magnetic field generated by the permanent magnet inside the bearing to provide support stiffness for the main shaft; the magnetic fluid bearing includes an upper bushing 101, an upper end cover 102, a semi-circular permanent magnet 103, a lower bushing 104, a lower end cover 105, and a magnetic isolation sheet 106. The upper bushing 101 and the lower bushing 104 are connected by bolts. The semi-circular permanent magnet 103 is placed in the cavity of the bushing and is sealed and fixed by the upper end cover 102 and the lower end cover 105. The magnetic isolation sheet is installed on both sides of the connection surface between the upper bushing 101 and the lower bushing 104. The upper bushing 101, the lower bushing 104, the upper end cover 102, and the lower end cover 105 are made of a magnetic conductive material. The material of the semi-circular permanent magnet 103 is an aluminum-nickel-cobalt-based permanent magnet alloy, and the magnetic isolation sheet 106 is a non-magnetic conductive material such as stainless steel, brass, bronze, etc.

[0026] When the main shaft is running, the motor stator 12 and the motor rotor 11 are used to drive the main shaft to rotate at a high speed, and the displacement detection mechanism is used to detect the chatter displacement of the main shaft. The magnetic force generated by the actuator stator pole 3 is used to suppress the chatter.

[0027] As Figure 2 and Figure 3As shown in the figure, the actuator stator pole 3 of the present invention includes a stator main body 4 and magnetic poles 5 arranged radially along the stator main body 4. An actuator coil 6 is wound around the magnetic pole 5 to form a control magnetic pole. The electromagnetic force generated at the corresponding magnetic pole 5 by energizing the actuator coil 6 is used to suppress the spindle chatter. The control magnetic pole formed by the actuator coil 6 can adjust the current based on the spindle vibration condition to actively suppress the spindle vibration. In some cases where the vibration amplitude is small, if the power is frequently turned on and off for vibration suppression, it is easy to increase the energy consumption. Therefore, in the magnetic pole 5 of the present invention, some magnetic poles are embedded with actuator stator magnets 21 to form bias magnetic poles. The actuator stator magnets 21 are made of neodymium iron boron material. The spindle vibration is controlled by the cooperation of the bias magnetic pole and the control magnetic pole. When the vibration is small, the spindle chatter can be suppressed by using the magnetic field formed by the bias magnetic pole itself, reducing the required energy consumption. Moreover, the combined vibration suppression form of the bias magnetic pole and the control magnetic pole can decouple the force in the radial direction, reducing the difficulty of vibration suppression control.

[0028] Preferably, along the circumferential direction of the stator main body 4 of the present invention, the control magnetic poles and the bias magnetic poles are arranged at intervals. In the embodiment of the present invention, the actuator stator pole 3 is a six-pole structure, among which, three are bias magnetic poles and three are control magnetic poles. During active vibration suppression, the magnetic field generated by the bias magnetic poles provides the main bearing force, and the electromagnetic force for vibration control is generated by the cooperation of the three groups of control magnetic poles.

[0029] The displacement detection mechanism of the present invention includes a sensor pressure plate 7 concentrically arranged with the spindle 1. A displacement sensor 8 for detecting the displacement of the spindle 1 is embedded in the sensor pressure plate 7. The displacement sensors 8 are evenly distributed along the circumferential direction of the spindle 1. The number of displacement sensors 8 is preferably 4 groups. Four eddy current displacement sensors are used to detect the radial displacement of the front end of the rotor in real time and directly transmit it to the controller for vibration suppression, without complex filtering and parameter calculation. In addition, the present invention is provided with a sensor detection ring 9 on the spindle 1. The sensor detection ring 9 is relatively fixed with the spindle 1 and rotates synchronously with the spindle 1. The eddy current sensor detects the vibration displacement of the spindle 1 by detecting the displacement of the sensor detection ring 9.

[0030] The sensor detection ring 9 of the present invention is made of cast copper alloy material. When detecting the displacement, the eddy current sensor directly detects the displacement of the copper ring. By using the high conductivity of copper, the upper limit of the detection frequency is increased to 20 kHz, so that the micro-amplitude high-frequency vibration of the spindle can be detected. Compared with the conventional displacement detection method, the present invention can improve the vibration detection accuracy and provide a strong guarantee for high-precision machining of the spindle.

[0031] For the convenience of the assembly of the electromagnetic actuator system, such as Figure 2As shown in the figure, the actuator stator pole 3 of the present invention is arranged inside the actuator housing 16 and fixed by the inner stator retaining ring 17 and the outer stator retaining ring 18 on both sides of the actuator stator pole 3. The sensor pressure plate 7 is fixed to the actuator housing 16 by bolts, and the outer stator retaining ring 18 is pressed tightly inside the actuator housing 16 by using the sensor pressure plate 7; through the integrated assembly of the displacement detection mechanism and the electromagnetic vibration suppression mechanism, the assembly accuracy can be effectively guaranteed, thereby reducing the cooperative matching accuracy between detection and vibration suppression affected by assembly errors; the sensor pressure plate 7, the outer stator retaining ring 18, the inner stator retaining ring 17, and the actuator housing 16 are made of aluminum alloy 7050 bar material.

[0032] The present invention also discloses a usage method based on the above high-speed electric spindle. The spindle is supported by magnetic fluid bearings arranged at both ends, and the motor rotor arranged on the spindle is driven to rotate by the motor stator to drive the spindle to rotate; during the operation of the spindle, the displacement detection mechanism obtains the flutter displacement direction and displacement distance of the spindle, and the electromagnetic vibration suppression mechanism applies an electromagnetic force to the spindle to suppress the spindle vibration; when suppressing the spindle flutter, the present invention first suppresses the spindle flutter by the magnetic force generated by the polarized poles of the electromagnetic vibration suppression mechanism. When the spindle vibration exceeds the suppression range of the bias poles, the control poles are then energized, and the magnitude and direction of the electromagnetic force of the control poles are changed by using the current to actively suppress the spindle.

[0033] The content not described in detail in the specification of the present invention belongs to the prior art well-known to those skilled in the art.

Claims

1. A high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing, characterized in that, It includes a main shaft (1), and the shaft body of the main shaft (1) is supported by a magnetic fluid bearing (19) provided; an electromagnetic actuator system for detecting and controlling the chatter of the main shaft is provided at the end of the main shaft (1). The electromagnetic actuator system includes a displacement detection mechanism for detecting the chatter displacement of the main shaft and an electromagnetic chatter suppression mechanism for applying an electromagnetic force to suppress the chatter of the main shaft according to the detection result of the displacement detection mechanism. The electromagnetic chatter suppression mechanism includes an actuator mover iron core ring (2) fixedly relative to the main shaft (1) and an actuator stator magnetic pole (3) concentrically arranged on the outer periphery of the actuator mover iron core ring (2). The magnetic force is applied to the actuator mover iron core ring (2) by the actuator stator magnetic pole (3) to suppress the chatter of the main shaft.

2. The high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing according to claim 1, characterized in that, The actuator stator magnetic pole (3) includes a stator main body (4) and magnetic poles (5) arranged radially along the stator main body (4). An actuator coil (6) is wound around the magnetic pole (5) to form a control magnetic pole, and the chatter of the main shaft is suppressed by the electromagnetic force generated at the corresponding magnetic pole (5) when the actuator coil (6) is energized.

3. The high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing according to claim 2, characterized in that, Among the magnetic poles (5), some magnetic poles are embedded with actuator stator magnets (21) to form bias magnetic poles, and the main shaft vibration is controlled by the cooperation of the bias magnetic poles and the control magnetic poles.

4. The high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing according to claim 3, wherein Along the circumferential direction of the stator main body (4), the control magnetic poles and the bias magnetic poles are arranged at intervals.

5. The high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing according to claim 4, wherein, The actuator stator magnetic pole (3) has a six-pole structure, among which, three are bias magnetic poles and three are control magnetic poles.

6. The high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing according to any one of claims 1-5, characterized in that, The displacement detection mechanism includes a sensor pressure plate (7) arranged concentrically with the main shaft (1). A displacement sensor (8) for detecting the displacement of the main shaft (1) is embedded in the sensor pressure plate (7), and the displacement sensors (8) are uniformly distributed along the circumferential direction of the main shaft (1).

7. The high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing according to claim 6, characterized in that, The displacement sensor (8) adopts an eddy current sensor. A sensor detection ring (9) is arranged on the main shaft (1). The sensor detection ring (9) remains relatively fixed with the main shaft (1) and rotates synchronously with the main shaft (1). The eddy current sensor detects the chatter displacement of the main shaft (1) by detecting the displacement of the sensor detection ring (9).

8. The high-speed electric spindle integrating an electromagnetic actuator and a magnetic fluid bearing according to claim 7, characterized in that The sensor detection ring (9) adopts a cast copper alloy material.

9. A method for using a high-speed electric spindle according to any one of claims 1-8, characterized in that, The main shaft is supported by magnetic fluid bearings provided at both ends, and the motor rotor arranged on the main shaft is driven to rotate by the motor stator to drive the rotation of the main shaft; during the operation of the main shaft, the displacement detection mechanism obtains the chatter displacement direction and displacement distance of the main shaft, and an electromagnetic force is applied to the main shaft by the electromagnetic chatter suppression mechanism to suppress the vibration of the main shaft.

10. The method for using a high-speed electric spindle according to claim 9, characterized in that, When suppressing the chatter of the main shaft, first, the magnetic force generated by the polarized magnetic poles of the electromagnetic chatter suppression mechanism is used to suppress the chatter of the main shaft. When the vibration of the main shaft exceeds the suppression range of the bias magnetic poles, the control magnetic poles are then energized, and the magnitude and direction of the electromagnetic force of the control magnetic poles are changed by the current to actively suppress the main shaft.

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