A radial-thrust pressure floating ring and magnetic suspension support electric spindle system

Abstract

This invention discloses a radial-impact thrust-supported electric spindle system with a floating ring and magnetic levitation support. Structurally, it comprises an electric spindle, end caps, bearing housings, a motor housing, an encoder, a thrust plate, a thrust plate nut, a radial-impact thrust-supported floating ring, a hydrodynamic gas bearing, a radial magnetic levitation bearing, a cooling jacket, a motor stator, permanent magnet plates, and a protective sleeve. The front and rear ends of the electric spindle are supported by a combination of radial magnetic levitation bearings, hydrodynamic gas bearings, and radial-impact thrust-supported floating rings. The hydrodynamic gas bearing has a herringbone groove machined on its inner side and a bearing gas groove machined on its end face near the radial-impact thrust-supported floating ring; the end face of the radial-impact thrust-supported floating ring has a floating ring gas groove machined on its end face near the thrust plate. This invention provides a radial-impact thrust-supported floating ring and magnetic levitation support system for the electric spindle, which can stably and effectively support the electric spindle under various operating conditions. The support method is contactless and frictionless, greatly improving the lifespan of the electric spindle and bearing system.

Description

Technical Field

[0001] The invention belongs to the technical field of bearing preparation, in particular to a radial-thrust pressure floating ring and a magnetic suspension support electric spindle system. Background Art

[0002] The electric spindle is a high-speed, precision unit that bears large radial and axial cutting loads. It integrates variable frequency speed regulation technology, high-speed bearing technology, and key manufacturing and assembly technology, among which high-speed bearing technology is the key technology in the electric spindle. The application of high-speed electric spindle bearings requires bearings with excellent performance. Improving speed performance, operating accuracy, and system stiffness are several major challenges facing the bearing industry. At present, the bearings used in high-speed electric spindles are mostly ceramic rolling bearings, magnetic bearings, and gas bearings. Ceramic rolling bearings have a very high temperature rise when running at high speed, and the centrifugal force of the rolling elements is large, which will cause bearing failure; magnetic levitation bearings use magnetic field force to support the rotor, and have the advantages of no contact, no friction, and no lubrication; in addition, the more notable feature is that the rotor can be actively controlled; dynamic pressure gas floating ring bearings have the advantages of high precision, compact structure, and low friction power consumption. The most notable feature is that they can increase the rotation speed of the shaft and are widely used in high-speed rotating machinery such as turbines and turbines; but dynamic pressure gas floating ring bearings have poor controllability. The most prominent disadvantage is that when the electric spindle is started, stopped or slowed down, the dynamic pressure effect is small, and a supporting air film cannot be formed, causing friction between the electric spindle and the bearing. Summary of the invention

[0003] The purpose of the present invention is to provide a radial-thrust pressure floating ring and magnetic levitation support electric spindle system, which aims to improve the stiffness and load-bearing capacity of the entire bearing system by addressing the problems of low load-bearing capacity and poor controllability of dynamic pressure gas bearings and friction between the electric spindle and the bearings when the electric spindle is started or slowed down.

[0004] The technical solution to achieve the purpose of the present invention is:

[0005] A radial-thrust pressure floating ring and magnetic suspension support electric spindle system, comprising a motor housing, bearing seats fixed at both ends of the motor housing, and an electric spindle, wherein a permanent magnet sheet and a motor stator are arranged between the electric spindle and the motor housing;

[0006] The electric spindle and the bearing seats on both sides are supported by radial magnetic bearings and hydrodynamic gas bearings; a radial-thrust floating ring is provided between the hydrodynamic gas bearing and the electric spindle, and a thrust plate is provided on the outside; the thrust plate is fastened to the electric spindle by a thrust plate nut; when the electric spindle rotates, the hydrodynamic gas bearing and the radial-thrust floating ring form an air film to act on the thrust plate, so that the electric spindle can achieve axial stillness;

[0007] The radial magnetic bearing and the hydrodynamic gas bearing work interactively; the radial magnetic bearing is used to generate electromagnetic force on the electric spindle when the electric spindle is started or slowed down; the hydrodynamic gas bearing is used to form a double-layer air film between the radial-thrust floating ring and the electric spindle when the electric spindle is working normally, so as to suspend the electric spindle.

[0008] Compared with the prior art, the present invention has the following significant advantages:

[0009] The radial-thrust floating ring and magnetic suspension support electric spindle system proposed in the present invention can stably and effectively support the electric spindle under different high and low working conditions. Under high-speed working conditions, the dynamic pressure effect of the dynamic pressure gas bearing is used to form a double-layer air film between the dynamic pressure gas bearing, the radial-thrust floating ring and the electric spindle, thereby improving the load-bearing capacity and rigidity of the entire bearing system; under low-speed working conditions or when the spindle is started and stopped, the controllability of the magnetic suspension bearing is used to detect the deflection information of the rotor through the displacement sensor, change the size of the coil current, adjust the position of the rotor, and avoid friction between the electric spindle and the bearing; at the same time, the thrust floating ring can not only bear radial loads, but also bear axial loads, thereby improving the stability of the bearing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the three-dimensional structure of the device of the present invention.

[0011] Figure 2 It is a schematic diagram of the overall cross-sectional structure of the device of the present invention.

[0012] Figure 3 This is a diagram showing the distribution of sensors in the device of the present invention.

[0013] Figure 4 (ab) are respectively the end view and cross-sectional view of the radial-thrust floating ring in the device of the present invention.

[0014] Figure 5 (ab) are respectively the end view and cross-sectional view of the dynamic pressure gas bearing in the device of the present invention.

[0015] In the figure: 1-electric spindle, 2-front end cover, 3-front bearing seat, 4-motor housing, 5-rear bearing seat, 6-rear end cover, 7-encoder, 8-thrust plate, 9-thrust floating ring, 10-front dynamic pressure gas bearing, 11-front radial magnetic bearing, 12-front sensor housing, 13-cooling jacket, 14-motor stator, 15-rear sensor housing, 16-rear radial magnetic bearing, 17-rear dynamic pressure gas bearing, 18-rear thrust floating ring, 19-magnetic bearing coil, 20-motor coil, 21-permanent magnet sheet, 22-protective cover, 23-thrust plate nut, 24-sensor, 25-floating ring air groove, 26-bearing air groove, 27-herringbone groove, A-water inlet, B-water outlet. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] like Figure 1-5 As shown, a radial-thrust floating ring and magnetic suspension support electric spindle system includes an electric spindle 1 connected to a motor, a front end cover 2, a front bearing seat 3, a motor housing 4, a rear bearing seat 5, a rear end cover 6, an encoder 7, a thrust plate 8, a front radial-thrust floating ring 9, a front dynamic pressure gas bearing 10, a front radial magnetic suspension bearing 11, a front sensor housing 12, a cooling sleeve 13, a motor stator 14, a rear sensor housing 15, a rear radial magnetic suspension bearing 16, a rear dynamic pressure gas bearing 17, a rear radial-thrust floating ring 18, a magnetic suspension bearing coil 19, a motor coil 20, a permanent magnet sheet 21, a protective sleeve 22, a thrust plate nut 23, a sensor 24, a floating ring air groove 25, a bearing air groove 26, and a herringbone groove 27.

[0018] The front end of the electric spindle 1 is supported by a front radial magnetic bearing 11, a front dynamic pressure gas bearing 10 and a front radial-thrust floating ring 9, and the rear end is supported by a rear radial magnetic bearing 16, a rear dynamic pressure gas bearing 17 and a rear radial-thrust floating ring 18.

[0019] The permanent magnet sheet 21 is nested on the electric spindle 1, and a protective sleeve 22 is provided on the outside, which is an interference fit; the motor stator 14 is installed on the outside of the protective sleeve 22, and the motor stator 14 and the cooling sleeve 13 are fastened and nested on the motor housing 4. The motor housing 4 is processed with a water inlet A and a water outlet B, and the front and rear bearing seats 3 and the rear bearing seats 5 are connected to the motor housing 4 by screws; the front bearing seat 3 is fixedly connected to the front cover 2 by screws; the rear bearing seat 5 is connected to the rear cover 6 by screws; the rear cover 6 is fixedly connected to the encoder 7.

[0020] like Figure 3 As shown, the front and rear radial magnetic suspension bearings (11, 16) are fixedly connected to the front and rear sensor housings (12, 15) respectively by screws; the front and rear radial magnetic suspension bearings (11, 16) are both wound with magnetic suspension bearing coils 19; and two vertically distributed sensors 24 are installed in the front and rear sensor housings (12, 15).

[0021] like Figure 4-5As shown, the inner sides of the front dynamic pressure gas bearing 10 and the rear dynamic pressure gas bearing 17 are processed with herringbone grooves 27, and the front radial-thrust floating ring 9 and the rear radial-thrust floating ring 18 are respectively arranged between the front dynamic pressure gas bearing 10, the rear dynamic pressure gas bearing 17 and the electric spindle 1; the outer sides of the front radial-thrust floating ring 9 and the rear radial-thrust floating ring 18 are provided with thrust discs 8, and the thrust discs 8 are fastened to the electric spindle 1 through thrust disc nuts 23, and are axially limited by the upper shoulder of the electric spindle 1. The end face of the front dynamic pressure gas bearing 10 close to the front radial-thrust floating ring 9 and the end face of the rear dynamic pressure gas bearing 17 close to the rear radial-thrust floating ring 18 are processed with bearing air grooves 26; the end faces of the front radial-thrust floating ring 9 and the rear radial-thrust floating ring 18 are processed with floating ring air grooves 25, and the floating ring air grooves 25 are processed only on the end faces close to the thrust disc 8. When the main shaft runs at high speed, the front and rear radial magnetic suspension bearings (11, 16), the front and rear radial-thrust floating rings (9, 18) and the electric main shaft 1 form a double-layer air film to support the radial load of the main shaft; the thrust surfaces of the front and rear dynamic pressure gas bearings (10, 17) are processed with bearing air grooves 26 and the thrust surfaces of the front and rear radial-thrust floating rings (9, 18) are processed with floating ring air grooves 25 to form a dynamic pressure effect to bear the axial load of the electric main shaft 1.

[0022] like Figure 1-5 As shown, a radial-thrust pressure-absorbing floating ring and magnetic suspension support electric spindle system has the following working principle: when the electric spindle is started or decelerated, the speed is relatively low, the radial magnetic suspension bearing starts to work, and the electric spindle is stably suspended under the action of electromagnetic force, thereby avoiding friction between the electric spindle and the bearing when the electric spindle is started or decelerated; when the speed of the electric spindle is relatively high, gas enters the bearing from both sides, and due to the viscosity of the lubricating gas, the radial-thrust floating ring rotates with the electric spindle, and the gas forms a double-layer gas film between the dynamic pressure gas bearing, the radial-thrust floating ring and the electric spindle, so that the electric spindle is stably suspended, and at this time the radial magnetic suspension bearing quits working; at the same time, the end faces of the radial-thrust floating ring and the dynamic pressure gas bearing are machined with gas grooves, and an gas film is formed between the radial-thrust floating ring and the thrust plate, and the dynamic pressure gas bearing and the radial-thrust floating ring form an gas film, and the gas film force acts evenly on the radial-thrust floating ring and the thrust plate, so that the electric spindle can achieve axial stillness. When the electric spindle is subject to external interference and its radial position deviates, the sensor receives a signal and calculates the deflection displacement of the spindle, thereby changing the current on a specific radial bearing coil accordingly, thereby changing the magnetic field generated by the bearing matrix, thereby generating a radial force on the spindle, causing the spindle to move radially, thereby achieving radial position adjustment.

Claims

1. A radial-thrust pressure floating ring and magnetic suspension support electric spindle system, comprising a motor housing, a bearing seat fixed at both ends of the motor housing, and an electric spindle, wherein a permanent magnet sheet and a motor stator are arranged between the electric spindle and the motor housing; characterized in that: The electric spindle and the bearing seats on both sides are supported by radial magnetic bearings and hydrodynamic gas bearings; a radial-thrust floating ring is provided between the hydrodynamic gas bearing and the electric spindle, and a thrust plate is provided outside the radial-thrust floating ring; the thrust plate is fastened to the electric spindle; when the electric spindle rotates, the hydrodynamic gas bearing and the radial-thrust floating ring form an air film to act on the thrust plate, so that the electric spindle can achieve axial stillness; The radial magnetic bearing and the hydrodynamic gas bearing work interactively; the radial magnetic bearing is used to generate electromagnetic force on the electric spindle when the electric spindle is started or decelerated; the hydrodynamic gas bearing is used to form a double-layer air film between the radial-thrust floating ring and the electric spindle when the electric spindle is working normally, so that the electric spindle is suspended; The dynamic pressure gas bearing has a herringbone groove on the radial inner side; the dynamic pressure gas bearing has a bearing air groove on the axial end face close to the radial-thrust floating ring; and the radial-thrust floating ring has a floating ring air groove on the end face close to the thrust plate.

2. The radial-thrust pressure floating ring and magnetic suspension support electric spindle system according to claim 1 is characterized in that: It also includes a displacement detection unit for detecting the radial position of the electric spindle. When the radial position of the electric spindle deviates, the current on the radial magnetic bearing coil changes, generating a radial force on the spindle to achieve radial position adjustment.

3. The radial-thrust pressure floating ring and magnetic suspension support electric spindle system according to claim 1 is characterized in that: It is characterized in that A cooling module is provided between the motor housing and the motor stator for cooling the motor.

4. The radial-thrust pressure floating ring and magnetic suspension support electric spindle system according to claim 3 is characterized in that: A cooling jacket is nested on the outside of the motor stator, and the cooling jacket is nested in the motor housing; a water inlet and a water outlet are processed on the motor housing, and a cooling module is formed with the cooling jacket.

5. The radial-thrust pressure floating ring and magnetic suspension support electric spindle system according to claim 1 is characterized in that: It is characterized in that An encoder is also provided on the rear end cover of the bearing seat.

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