CN118748485A - A high-speed and high-precision spindle motor - Google Patents

Abstract

The present invention relates to the technical field of high-speed motors, specifically a high-speed and high-precision spindle motor, comprising a housing, a stator fixed in the housing, a front cover and a rear cover respectively fixed at the front and rear of the housing, and a rotor rotatably connected between the front cover and the rear cover; the front cover and the rear cover are respectively fixedly connected with a front metal sleeve and a rear metal sleeve, the inner holes of the front metal sleeve and the rear metal sleeve are equipped with bearings, and the two ends of the rotor mandrel are respectively connected to the bearings; the end of the rotor mandrel extending out of the rear cover is fixedly connected with a balancing ring, and the balancing ring is evenly distributed with a plurality of counterweight holes along the circumference, and the counterweight screws can be threadedly connected in the counterweight holes. The present invention is conducive to quickly, conveniently and accurately adjusting the dynamic balance of the rotor, reducing the vibration value of the motor at high speed, and can make the motor speed reach 24,000 rpm, breaking through the current domestic motor speed bottleneck, and raising the motor speed improvement technology to a new height.

Description

A high-speed and high-precision spindle motor

Technical Field

The invention relates to the technical field of high-speed motors, and in particular to a high-speed and high-precision spindle motor.

Background Art

Spindle motors, also called high-speed motors, usually refer to AC motors with speeds exceeding 10,000 rpm. They usually have significant characteristics such as high speed, high response speed, high precision, and low vibration. They are widely used in CNC machine tools, building materials, plastic machinery, textiles, light industrial machinery, metallurgy, conveyor lines, and other occasions that require speed regulation.

At present, the maximum speed of domestic spindle motors can reach 23,000 rpm. The higher the motor speed, the higher the transmission efficiency and the higher the output power. At the same time, the high-speed motor has a faster response speed and can start and stop quickly within milliseconds or even microseconds, achieving more flexible control and adapting to various rapidly changing application scenarios.

During the research and development process, the inventor discovered that as the motor speed increases, the motor vibration value will gradually increase; and excessive motor vibration will accelerate the wear of core components such as the motor shaft and bearings, shorten the service life of bearings and core components, and increase maintenance costs. Long-term vibration will also cause the insulation material between the stator windings to be impacted and squeezed, resulting in reduced insulation performance and causing short-circuit failures; or excessive vibration may cause parts to loosen, causing collisions between the rotor and the stator, causing serious damage to the motor. The inventor used conventional methods to find the cause of the motor vibration, correct the dynamic balance of the rotor, check the motor structural defects, and detect the locking of the motor components, but still did not solve the problem of the motor's large vibration value at high speeds. Therefore, the market urgently needs a motor structure to solve the above problems and break through the speed bottleneck of existing high-speed motors.

Summary of the invention

The present invention provides a high-speed and high-precision spindle motor, which can solve the problem that the motor is easily damaged due to excessively large vibration value when the motor is running at high speed.

The present application provides the following technical solution: A high-speed and high-precision spindle motor, comprising a housing, a stator fixed in the housing, a front end cover and a rear end cover respectively fixed at the front and rear parts of the housing, and a rotor rotatably connected between the front end cover and the rear end cover;

The front cover and the rear cover are respectively fixedly connected with a front metal sleeve and a rear metal sleeve, each of which has an inner hole, and a bearing is installed in the inner hole, and the two ends of the core shaft of the rotor are respectively rotatably connected to the bearings;

A balancing ring is fixedly connected to the end of the rotor's core shaft extending out of the rear end cover. A plurality of balancing weight holes are evenly distributed along the circumference of the balancing ring, and balancing weight screws can be threadedly connected in the balancing weight holes.

Invention concept:

During the research and development process, the inventor discovered that as the motor speed increases, the motor vibration value will gradually increase. In order to avoid motor failure caused by excessive vibration values, the inventor performed troubleshooting according to conventional methods. The most likely cause of motor vibration is usually because the dynamic balance of the rotor is large, causing the motor to vibrate when the rotor rotates at high speed. Therefore, the inventor disassembled the rotor and performed a dynamic balance test. It was found that the dynamic balance value of the rotor was still within the qualified range. However, after the rotor was put back into the motor, the vibration value of the motor as a whole would still exceed the tolerance at high speed. Therefore, the inventor conducted routine inspections on the structural defects and locking conditions of other motor components except the rotor, and no problems were found. Therefore, the inventor suspected that the problem might be caused by the installation position of the rotor on the motor as a whole. The two ends of the rotor are rotatably connected to the front cover and the rear cover respectively through bearings, and the front cover and The rear end cover is usually formed in one piece by a casting process, and the bearing mounting holes are machined after casting. However, there will inevitably be errors in the processing. The errors will cause the centers of the bearing mounting holes on the front and rear covers to not be guaranteed to be on the same center line. At the same time, there will be processing errors in the rotor itself. In addition, the internal quality of the rotor raw materials is uneven, and the mass of some parts is too large, so the center of mass will deviate when the rotor rotates. Although the dynamic balance value of the rotor is detected separately or the bearing mounting hole accuracy is measured separately, the detection values are all within the qualified range, but after the rotor is installed on the bearing, the processing error and the installation error will be superimposed, thereby amplifying the dynamic balance value of the rotor when it rotates. This is why the parameters of the components are normal when they are detected separately, but after installation, the vibration value will exceed the standard when the speed is increased; therefore, the focus is on how to solve the dynamic balance adjustment of the rotor after installation, and how to adjust the position of the bearing mounting hole.

There are two difficulties in solving the above problems:

First, the uniformity of the internal mass distribution of the rotor is related to the molding of the raw materials, and there will inevitably be an eccentricity error of the center of mass. In addition, the outer dimensions of the rotor have been finalized and the rotor cannot be further processed. Therefore, the conventional method is to add a counterweight block to the end face of the rotor, and the location of the counterweight block is usually selected on the rotor core outside the rotor shaft. The reason is that the rotor core accounts for the largest proportion of the mass of the entire rotor. At the same time, the rotor core is shorter than the rotor shaft and the mass is more concentrated. It is more appropriate to set the counterweight block on the rotor core, which can more effectively adjust the mass distribution of the rotor and achieve a better balancing effect; but the rotor is installed inside the motor. If the conventional motor needs to adjust the rotor counterweight block, the end cover and bearing must be removed to expose the end face of the rotor core to facilitate the addition of the counterweight block. During dynamic balancing adjustment, it is necessary to try and change the position of the counterweight block multiple times to achieve the optimal balancing effect, which requires frequent disassembly and assembly of the motor end cover and bearing, which will cause changes in the installation errors of the rotor ends and the bearings, making the dynamic balancing adjustment inaccurate, and ultimately greatly slowing down the adjustment time.

Second, in order to ensure strength and rigidity, the front and rear covers of traditional motors are usually formed in one piece using a casting process, and the bearing mounting holes are directly machined into a groove on the front and rear covers for installing bearings. Once the bearing installation is completed, its position basically cannot be adjusted; if it needs to be adjusted, the end cover needs to be replaced as a whole, which will greatly increase the R&D cost.

Therefore, based on the above two difficulties, the inventor proposed a new motor structure, which uses a technical development idea different from the conventional one. A balancing ring is added to the end of the rotor core shaft extending out of the rear end cover (instead of on the iron core of the rotor); at the same time, a front metal sleeve and a rear metal sleeve are arranged on the front end cover and the rear end cover (without adopting the traditional one-piece casting process) to solve the above problems.

Beneficial effects:

1. A balancing ring is added to the end of the rotor's core shaft that extends out of the rear end cover. When the vibration value of the whole machine is detected, if the dynamic balance of the rotor needs to be adjusted, there is no need to remove the rear end cover and the bearing. Instead, the fan cover connected to the rear end cover screws only need to be removed, and the counterweight screws can be added or removed on the balancing ring to adjust the dynamic balance of the rotor. This avoids the disadvantage that the traditional motor has a counterweight structure on the rotor core, and the motor end cover and bearing need to be removed to adjust the counterweight, resulting in repeated installation of the rotor and bearing, which causes errors in the dynamic balance detection accuracy. When the motor is tested as a whole, the dynamic balance of the rotor can be adjusted quickly, conveniently and accurately, reducing the vibration value of the motor at high speed, and enabling the motor speed to reach 24,000 rpm, breaking through the current domestic motor speed bottleneck and bringing the speed enhancement technology of high-speed motors to a new level.

2. A front metal sleeve and a rear metal sleeve are respectively provided on the front cover and the rear cover, and bearing holes are opened on the front metal sleeve and the rear metal sleeve. When the bearing installation centering position of the front cover and the rear cover needs to be adjusted, the front metal sleeve and the rear metal sleeve can be removed and replaced from the front cover and the rear cover, and the bearing installation holes on the metal sleeves can be re-machined to correct the bearing installation hole reference to the same center line, thereby avoiding the disadvantage that when adjusting the bearing installation centering position of the traditional motor, the end cover needs to be replaced as a whole, resulting in additional cost increase. Since the volume of the front metal sleeve and the rear metal sleeve is greatly reduced compared to the end cover, replacing the metal sleeve alone can not only reduce the processing and manufacturing cost, but also the volume of the metal sleeve is smaller, it is easier to ensure the processing accuracy during processing, and the bearing installation centering position is more accurate, thereby reducing the installation error of the rotor core shaft to the bearing, improving the stability of the rotor during rotation, and is beneficial to the operation stability when the motor speed is increased.

Furthermore, a shaft end retaining ring is fixedly provided inside the front end cover, and the shaft end retaining ring and the front metal sleeve are arranged in sequence toward the direction of the rotor, and the shaft end retaining ring is used to clamp the bearing; the shaft end retaining ring and the front metal sleeve are both stepped structures, both of which include a large diameter end and a small diameter end, and the small diameter end of the shaft end retaining ring extends into the hole of the small diameter end of the front metal sleeve.

Beneficial effect: Since the side where the front end cover is located is the side where the motor rotor core shaft is connected to the load machine, the bearing on this side is more prone to damage. This structure can directly remove the shaft end retaining ring on the front end cover without removing the entire front end cover, and the use of the bearing can be observed from the inner hole of the front metal sleeve, which is helpful for replacing the bearing and improving the convenience of disassembly and assembly of parts; at the same time, the inner hole of the small diameter end of the front metal sleeve circumferentially centers the outer circle of the small diameter end of the bearing retaining ring, so that when installing the shaft end retaining ring, it is more convenient and quick to fix it on the front end cover.

Furthermore, the inner hole of the rear metal sleeve is coaxially provided with a stepped hole, the diameter of the stepped hole is larger than the inner hole diameter of the rear metal sleeve, the bearing is installed in the stepped hole, and a wave spring is provided between the end face of the bearing and the bottom face of the stepped hole.

Beneficial effect: The side where the rear end cover is located is the side where the motor is connected to the fan. The end of the rotor core shaft on this side is subject to less load, and the bearing does not need to be replaced frequently. Therefore, a stepped hole is set in the rear metal sleeve. The stepped hole can limit the bearing axially, which can enhance the axial stability of the bearing. At the same time, the elastic force of the wave spring can also form an axial buffer for the bearing, which can protect the bearing end face when the rotor moves axially.

Furthermore, a magnetic ring encoder and a locking nut are fixed to one end of the rotor core shaft close to the rear end cover, and the locking nut is used to axially press and fix the balance ring on the magnetic ring end face of the magnetic ring encoder.

Beneficial effect: The locking nut presses the balancing ring against the end face of the magnetic ring. When the rotor core shaft rotates, the magnetic ring and the balancing ring can rotate along with the rotor core shaft, so that the magnetic ring encoder can measure the position and speed of the motor rotor in real time. At the same time, it is also convenient to add a counterweight screw to the balancing ring to adjust the dynamic balance of the rotor core shaft.

Furthermore, annular grooves are provided on the inner hole wall of the front metal sleeve and the stepped hole wall of the rear metal sleeve, and sealing rings are filled in the annular grooves.

Beneficial effect: The sealing ring can seal the bearing and the front metal sleeve and the rear metal sleeve, preventing dust and other impurities from entering the inner holes of the front metal sleeve and the rear metal sleeve.

Furthermore, a dust cover is fixedly connected to the rear end cover, and the magnetic ring encoder, the balance ring and the locking nut are all located in the space formed by the rear end cover and the dust cover.

Beneficial effect: The dust cover can prevent dust and impurities from entering the counterweight hole of the balance ring and the bearing in the rear end cover, affecting the installation of the counterweight screw or preventing dust and impurities from clogging the rolling clearance of the bearing ball and avoiding the bearing from rotating and jamming.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view of the present invention.

FIG. 2 is an enlarged view of the front end cover portion in FIG. 1 .

FIG. 3 is an enlarged view of the rear end cover portion in FIG. 1 .

DETAILED DESCRIPTION

The following is further described in detail through specific implementation methods:

The marks in the drawings in the specification include: rotor 1, sleeve 2, sealing ring 3, front metal sleeve 4, front bearing 401, rear bearing 402, stator 5, magnetic ring encoder 6, magnetic ring 601, rear end cover 7, dust cover 8, cable clamping connector 9, junction box 10, fan cover 11, locking nut 12, balancing ring 13, wave spring 14, rear metal sleeve 15, front end cover 16, shaft end retaining ring 17.

Embodiment 1

As shown in Figures 1 to 3, a high-speed and high-precision spindle motor includes a housing, a stator 5 fixed in the housing, a front end cover 16 and a rear end cover 7 fixed to the front and rear parts of the housing respectively, and a rotor 1 penetrating the front end cover 16 and the rear end cover 7 and rotatably connected thereto; a fan cover 11 is fixed to the rear part of the housing.

A fan assembly for cooling the motor is installed in the fan cover 11, and a junction box 10 is fixed on the upper rear of the housing. The junction box 10 is used to connect the internal wires of the motor with the power supply outside the motor.

The front cover 16 and the rear cover 7 are provided with mounting holes, and the front metal sleeve 4 and the rear metal sleeve 15 are respectively interference-fitted in the mounting holes. The front metal sleeve 4 and the rear metal sleeve 15 are both made of cast iron, which has good castability, wear resistance and shock absorption. It can not only withstand high compression loads, but also has good shock absorption ability and can reduce mechanical vibration. Bearings are installed in the inner holes of the front metal sleeve 4 and the rear metal sleeve 15. The bearings include a front bearing 401 and a rear bearing 402. The front bearing 401 and the rear bearing 402 are both angular contact ball bearings. The angular contact ball bearings can withstand higher axial and radial loads, which is conducive to the increase of the motor speed. The two ends of the core shaft of the rotor 1 are rotatably connected to the front bearing 401 and the rear bearing 402 respectively.

As shown in Figure 2, a shaft end retaining ring 17 is also fixedly provided inside the front end cover 16, and the shaft end retaining ring 17 and the front metal sleeve are arranged in sequence toward the direction of the rotor, and an outer step is provided on the outer circle of the front metal sleeve 4, and the outer step is used to limit the installation position of the front metal sleeve 4 on the front end cover 16; the shaft end retaining ring 17 and the front metal sleeve 4 are both stepped structures, both of which include a large diameter end and a small diameter end, and the small diameter end of the shaft end retaining ring 17 extends into the hole at the small diameter end of the front metal sleeve 4, and presses against the outer ring end face of the front bearing 401, thereby axially limiting the front bearing 401, and at the same time, a plurality of screw holes are circumferentially provided on the large diameter end of the shaft end retaining ring 17, and is connected to the outer end face of the front end cover 16 by screws, and the inner hole of the small diameter end of the front metal sleeve 4 circumferentially centers the outer circle of the small diameter end of the bearing retaining ring 17, so that when installing the shaft end retaining ring 17, it is more convenient and quick to fix it on the front end cover 16. A sleeve hole is opened on the axis of the metal sleeve shaft end retaining ring 17, and a sleeve 2 is fixed in the sleeve hole. The inner hole of the sleeve 2 is sleeved on the core shaft of the rotor 1. The sleeve 2 can reduce the wear between the core shaft of the rotor 1 and the shaft end retaining ring 17 and reduce noise. The shaft end retaining ring 17 and the sleeve 2 can prevent dust and impurities outside the motor from entering the front end cover 16 to avoid affecting the rotation of the front bearing 401, thereby improving the service life of the bearing.

As shown in FIG3 , the rear metal sleeve 15 is also provided with a stepped hole coaxially with its inner hole, and the diameter of the stepped hole is larger than the inner hole diameter of the rear metal sleeve (the opening of the stepped hole in FIG3 is to the left), and the rear bearing 402 is installed in the stepped hole, and a wave spring 14 is provided between the end face of the rear bearing 402 and the bottom face of the stepped hole, and the elastic force of the wave spring 14 can form an axial buffer for the bearing, and can protect the end face of the bearing when the rotor 1 moves axially. An annular groove is provided on the inner hole wall of the front metal sleeve 4 and the stepped hole wall of the rear metal sleeve 15, and the annular groove is filled with a sealing ring 3.

The rear part of the core shaft of the rotor 1 axially extends out from the inner hole of the rear end cover 7, and the upper part of the extended rod is axially provided with a magnetic ring encoder 6, a balancing ring 13 and a locking nut 12 in sequence. The magnetic head at the upper part of the magnetic ring encoder 6 is fixed to the end face of the rear end cover 7 by screws. The lower part of the magnetic ring encoder 6 is a magnetic ring 601, which is sleeved on the core shaft of the rotor 1 and can rotate with the core shaft of the rotor 1; the locking nut 12 is threadedly connected to the end part of the core shaft of the rotor 1, and the balancing ring 13 and the core shaft of the rotor 1 are clearance-fitted. Tightening the locking nut 12 can press the balancing ring 13 against the end face of the magnetic ring 601, so that the balancing ring 13 can also rotate with the core shaft of the rotor 1. There are multiple axially opened counterweight holes evenly distributed along the circumference of the balancing ring 13, and the counterweight holes are threaded holes for easy connection of counterweight screws. The rear end cover 7 is also screwed with a dust cover 8, which can cover the magnetic ring encoder 6, the balance ring 13 and the locking nut 12, and can prevent dust and impurities in the fan cover 11 from entering, and avoid blocking the counterweight hole in the balance ring 13 or the rotation gap of the rear bearing 402. A cable clamping connector 9 is also installed above the dust cover 8, and the connecting wires of the magnetic ring encoder 6 located in the dust cover 8 can pass through the cable clamping connector 9 to access the junction box 10 above the shell.

The dynamic balance adjustment method of the rotor 1 of this motor structure is as follows:

After removing the fan cover 11 and the dust cover 8 and inspecting the whole machine with testing equipment, if it is necessary to adjust the dynamic balance of the rotor 1, the dynamic balance of the motor can be adjusted multiple times by adding or removing the counterweight screws on the counterweight holes in appropriate positions on the balancing ring 13 according to the dynamic balance test results. This avoids the disadvantage of traditional motors that require opening the end cover or removing the bearings to complete the dynamic balance adjustment, improves the adjustment accuracy and speed, and thus can increase the motor speed to a maximum of 24,000 rpm, and the motor shaft end temperature value and motor vibration value can be within a controllable range.

The following is a record of the inventor's experiment on high-speed operation of the motor during the research and development process:

As can be seen from the table, as the motor speed increases, the shaft end temperature of the motor rotor and the motor vibration value gradually increase. When the maximum is 24,000 rpm, according to the actual detection requirements, the motor is stopped after running from a low speed to a high speed for a period of time, so that the internal temperature is reduced to the ambient temperature or close to the ambient temperature, and the vibration measurement data is obtained in the cold start state. This vibration value is an important parameter for evaluating the mechanical state of the equipment before the initial startup, which can reflect the potential problems such as the balance, mechanical failure, bearing condition, and alignment problems of the equipment without the influence of thermal effects. For a high-speed motor of 20,000 rpm, the vibration value standard after running the machine should not be higher than 1.5 mm/s. In this application, the motor speed has reached 24,000 rpm, and the motor vibration value is 0.421 mm/s, which is still within the standard range and far less than the standard value, proving that the motor structure of the present invention can effectively improve the stability of the motor at high speeds, which is of great significance for breaking through the bottleneck of high motor speeds.

The above are only embodiments of the present invention. The invention is not limited to the field involved in this implementation case. The common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims (6)

1. The utility model provides a high-speed high accuracy spindle motor, includes the shell, fixes the stator in the shell, fixes front end housing and rear end cap at shell front portion and rear portion respectively to and wear to locate on front end housing and the rear end cap and rotate the rotor of being connected with it, its characterized in that:

The front end cover and the rear end cover are respectively fixedly connected with a front metal sleeve and a rear metal sleeve, bearings are respectively arranged on the front metal sleeve and the rear metal sleeve, and two ends of a mandrel of the rotor are respectively connected to the bearings;

The end part of the central spindle of the rotor, which extends out of the rear end cover, is fixedly connected with a balance ring, a plurality of balance weight holes are uniformly distributed on the balance ring along the circumference, and the balance weight holes can be connected with balance weight screws in a threaded manner.

2. A high-speed high-precision spindle motor as claimed in claim 1, wherein: the front end cover is internally and fixedly provided with a shaft end check ring, the shaft end check ring and the front metal sleeve are sequentially arranged towards the direction of the rotor, and the shaft end check ring is used for compressing the bearing; the shaft end check ring and the front metal sleeve are of stepped structures, each of the shaft end check ring and the front metal sleeve comprises a large-diameter end and a small-diameter end, and the small-diameter end of the shaft end check ring extends into a hole of the small-diameter end of the front metal sleeve.

3. A high-speed high-precision spindle motor as claimed in claim 2, wherein: the inner hole of the rear metal sleeve is also coaxially provided with a stepped hole, the diameter of the stepped hole is larger than that of the inner hole of the rear metal sleeve, the bearing is arranged in the stepped hole, and a wave spring is arranged between the end face of the bearing and the bottom face of the stepped hole.

4. A high-speed high-precision spindle motor as claimed in claim 3, wherein: and one end, close to the rear end cover, of the core shaft of the rotor is respectively fixed with a magnetic ring encoder and a locking nut, and the locking nut is used for axially pressing and fixing the balance ring on the magnetic ring end face of the magnetic ring encoder.

5. A high speed high precision spindle motor as defined in claim 4, wherein: the inner hole wall of the front metal sleeve and the stepped hole wall of the rear metal sleeve are provided with annular grooves, and sealing rings are filled in the annular grooves.

6. A high speed high precision spindle motor as defined in claim 5, wherein: and the rear end cover is fixedly connected with a dust cover, and the magnetic ring encoder, the balance ring and the locking nut are all positioned in a space formed by the rear end cover and the dust cover.