CN219403854U - A High Precision Internal Grinding Electric Spindle - Google Patents

Abstract

The utility model discloses a high-precision internal grinding electric main shaft, which comprises a main shaft shell, a main shaft body, bearing group parts, a rotor, a stator, a cooling system and a lubricating system. There is a rotor in the middle of the main shaft, and a corresponding stator is installed outside the rotor. The stator is installed inside the housing. A cooling water jacket is installed in the cavity between the stator and the housing. A tail cover is installed on the rear end of the housing. The front and rear ends of the main shaft body are respectively supported by the front and rear bearing group components. The utility model has the beneficial effects that: the electric spindle is equipped with a cooling system, the coolant is water, and a cooling cycle is formed in the electric spindle, which effectively reduces the heat generation of the synchronous motor composed of the rotor and the stator; the electric spindle is lubricated by oil and gas, which effectively reduces the heat generation of the bearing friction, reduces the thermal deformation of the main shaft, and reduces the wear of the main shaft;

Description

A High Precision Internal Grinding Electric Spindle

technical field

The utility model relates to the technical field of electric spindles, in particular to a high-precision internal grinding electric spindle.

Background technique

The high-speed precision internal grinding electric spindle is the core component of high-speed grinding, which integrates a variety of technical units. With the development of high-speed grinding technology, modern society has higher and higher requirements for workpiece grinding quality. The accuracy of the electric spindle is directly related to the grinding accuracy, which affects the processing accuracy, processing efficiency and processing stability of CNC machine tools. Therefore, it is very important to design an electric spindle structure with high machining accuracy.

Bearings are the core supporting components of the motorized spindle system. The stiffness and precision of the high-speed motorized spindle are closely related to the type, size and precision grade of the selected bearings, the level of assembly skills, the configuration method, and the size of the preload. Angular contact ball bearings can bear radial load and axial load at the same time, and can meet the requirements of speed limit, load capacity, rigidity, precision and other requirements at higher speeds. However, ordinary all-steel ball angular contactor bearings will increase the friction and heat of the bearing due to the increase of centrifugal force and gyro torque, and reduce the life of the bearing. Selecting the appropriate bearing material is very important for the performance of the electric spindle.

The preloading methods of the bearing mainly include constant position preloading and constant force preloading. The preloading of the bearing can improve the rigidity of the bearing, suppress vibration, and have a great influence on the rotation accuracy of the electric spindle. However, in the positioning preload mode, as the speed increases, the frictional heat of the bearing increases, the centrifugal force of the rolling elements increases the pressure on the outer ring channel of the bearing, and the dynamic stiffness of the bearing will continue to increase, which will affect the life of the bearing.

As the speed of the high-speed electric spindle increases, the heat generated by the friction of the bearing increases, and the heat generated will be transmitted to the spindle, resulting in a certain amount of thermal deformation of the spindle in the axial and radial directions, and the temperature difference caused by the different heat generation of the front and rear bearings will cause thermal deformation of the spindle and affect the machining accuracy of the machine tool.

Bearing raceway parameters and axial preload are important factors affecting the rotation accuracy of the spindle. The size of the bearing preload and the selection of bearing channel parameters will have a coupling effect on the spindle rotation accuracy. Matching reasonable preload and bearing channel parameters can effectively improve the spindle accuracy;

The influence of these factors on the performance of the electric spindle is seldom considered comprehensively in the design of the existing electric spindle, which leads to the limitation of the machining accuracy, production efficiency and equipment performance of the spindle. It is very necessary to adjust and optimize the spindle structure and select appropriate parameters to improve the precision and production efficiency of the electric spindle.

Utility model content

The purpose of this utility model is to overcome the deficiencies in the prior art and provide a high-precision internal grinding electric spindle; the electric spindle is equipped with a cooling system, the coolant is water, and a cooling cycle is formed in the electric spindle, which can effectively reduce the heat generation of the synchronous motor composed of the rotor and the stator; the electric spindle is lubricated by oil and gas, which can effectively reduce the heat generation of the bearing friction, reduce the thermal deformation of the main shaft, and reduce the wear of the main shaft;

The technical scheme of the utility model is specifically introduced as follows.

A high-precision internal grinding electric spindle, which includes a shell, a main shaft body, a rotor, a stator, a front bearing assembly, a rear bearing assembly, a spring preload assembly, a cooling system, and a lubrication system; wherein:

There is a rotor in the middle of the main shaft body, a stator is arranged outside the rotor, and the stator is installed inside the housing. The front and rear ends of the main shaft body are respectively supported by the front bearing group parts and the rear bearing group parts. The front bearing group parts and the rear bearing group parts respectively include bearing groups, flanges and spacers. Set at the rear end of the dense ball bearing;

The cooling system includes a cooling water jacket, a water tank, a cooling liquid inlet and a cooling liquid outlet. The cooling water jacket is arranged in the cavity between the stator and the housing, the water tank is arranged in the cooling water jacket, the cooling liquid inlet and the cooling liquid outlet are arranged on the tail cover provided on the rear end of the housing, and the water tank is connected to the cooling liquid inlet and the cooling liquid outlet;

The lubrication system includes an oil delivery pipe, an oil-air lubrication inlet, an air-seal air inlet, an air-seal skeleton and an oil inlet hole. The oil delivery pipe is arranged in the casing, the oil-air lubrication inlet is arranged on the tail cover, the oil inlet hole is arranged on the septa of the front bearing assembly and the rear bearing assembly, the oil delivery pipe is connected to the oil-air lubrication inlet, the oil inlet hole and the air seal skeleton, and the air seal skeleton is set on the bearing lock nut at the front end of the main shaft body.

In the utility model, the two bearings in the bearing group are configured in series DT mode, and the bearings are angular contact ball bearings.

In the utility model, the spacer includes an inner spacer and an outer spacer, the inner spacer is arranged on the inner side of the two bearings, and the outer spacer is arranged on the outer side of the two bearings.

In the utility model, the oil inlet hole includes an axial oil inlet hole and a radial oil inlet hole, and the oil inlet hole is arranged on the outer spacer.

In the utility model, the spring pre-tightening assembly includes a washer and a pre-tightening spring, the washer is arranged at the rear end of the dense ball bearing, and the pre-tightening spring presses against the end surface of the washer.

In the utility model, the front end of the flange at the front end of the main shaft body is provided with a front bearing gland, the front end of the front bearing gland is equipped with an air-tight gland, and the rear end of the flange at the rear end of the main shaft body is equipped with a tail baffle.

Compared with the prior art, the beneficial effects of the utility model are as follows:

1. The high-precision internal grinding electric spindle adopts angular contact ball bearings. The bearing balls of the bearings are made of ceramic materials, which are resistant to high temperature and have a small friction coefficient, so that the electric spindle has the advantages of high speed, high rigidity and long life. The angular contact ball bearings at the front and rear ends of the electric spindle adopt a series DT configuration, which can withstand large axial loads and improve the axial rigidity of the spindle.

2. The preloading method of the high-precision internal grinding electric spindle is constant pressure preloading, and the constant pressure is applied to the bearing through the preloading spring. Under this preloading method, the bearing preloading force is constant, and it is not easy to be affected by temperature and speed. By applying appropriate preload to match the bearing raceway, the spindle can achieve high precision requirements.

3. The high-precision internal grinding electric spindle is lubricated by oil and air, which can effectively reduce the wear of the bearing and the heat generated by friction, reduce the thermal deformation of the spindle, and thus improve the machining accuracy of the spindle.

4. The cooling system of the high-precision internal grinding electric spindle adopts a water-cooling method, forming a circulating cooling circuit inside the spindle, which can effectively take away the heat generated by the motor and reduce the influence of the motor heating on the spindle unit.

Description of drawings

Figure 1 is a schematic diagram of the structure of the utility model's high-precision internal grinding electric spindle.

Figure 2 is the tail cover diagram of the high-precision internal grinding electric spindle.

Fig. 3 is a schematic cross-sectional view of the structure of the utility model's high-precision internal grinding electric spindle.

Fig. 4 is a structural section A-A diagram of the utility model's high-precision internal grinding electric spindle.

Fig. 5 is a B-B diagram of the structural section of the high-precision internal grinding electric spindle of the utility model.

Fig. 6 is a C-C diagram of the structural section of the high-precision internal grinding electric spindle of the utility model.

Fig. 7 is a D-D diagram of the structural section of the high-precision internal grinding electric spindle of the utility model.

Notes on drawings:

1-housing; 2-main shaft; 3-rotor; 4-stator; 5-cooling water jacket; 6-tail cover; 7-oil and air lubrication inlet; 8-coolant inlet; 9-coolant outlet; 10-gas seal air inlet; 0-ball bearing; 21-inner septum; 22-outer septum; 23-washer; 24-preload spring; 25-air seal skeleton; 26-front bearing gland; 27-air seal gland;

Detailed ways

Below in conjunction with accompanying drawing, the specific embodiment of the present utility model is described in further detail.

Example 1

The utility model provides a high-precision internal grinding electric spindle, which grinds various internal holes of workpieces, including cylindrical through holes, blind holes, stepped holes and conical holes, etc.

As shown in Figure 1-7, a high-precision internal grinding electric spindle mainly includes a housing 1, a spindle body 2, bearing assembly components, a rotor 3, a stator 4, a cooling system and a lubrication system. The rotor 3 is sleeved in the middle of the main shaft body 2, and the rotor 3 is provided with a corresponding stator 4, and the stator 4 is installed inside the housing 1; the rotor 3 and the stator 4 constitute a synchronous motor, the stator 4 is a coil, and the rotor 3 is a magnet. A tail cover 6 is installed on the rear end of the housing 1, and an oil-air lubrication inlet 7, a coolant inlet 8, a coolant outlet 9, an air-tight air inlet 10 and an oil return hole 11 are arranged on the outer end of the tail cover 6.

The front and rear ends of the spindle body 2 are respectively supported by front and rear bearing components; the internal grinding electric spindle is equipped with a cooling system, and a cooling water jacket 5 is installed on the outside of the stator 4, and a water tank 12 is arranged on the outside, and the water tank 12 is connected with the coolant inlet 8 and the coolant outlet 9 installed on the tail cover 6 of the housing 1; The bearing is lubricated with oil and air; the internal grinding electric spindle is equipped with a spring preload assembly at the rear end of the rear bearing part.

The bearing group components include bearing groups installed at the front and rear ends of the main shaft body 2 respectively. The front and rear end bearing groups have two bearings 15 respectively. The front and rear bearing groups are respectively fitted with a front bearing flange 16 and a rear bearing flange 17. The front bearing group is positioned and locked by the front bearing lock nut 18 pressed on the front end of the bearing 15. The front and rear end bearings 15 are angular contact ball bearings. The bearing balls of the bearings 15 are made of ceramic materials, which are high temperature resistant, have a small friction coefficient, have a high rotational speed, and have a lifespan 2-3 times that of ordinary bearings, making the electric spindle have the advantages of high speed, high rigidity, and long life. Both the front and rear end angular contact ball bearing sets adopt DT configuration, under this configuration, the bearing 15 can bear relatively large axial load and has high axial rigidity. A spacer is arranged between each bearing 15 of the front and rear end bearing groups, including an inner spacer 21 and an outer spacer 22. The inner spacer 21 is pressed against the inner side of the adjacent bearing 15, and the inner spacer 21 is used to adjust the clearance and preload of the bearing 15; the outer spacer 22 is pressed against the outer side of the adjacent bearing 15. The outer spacer 22 is provided with radial and axial oil inlet holes 14, which are connected to the oil delivery pipe 13 to lubricate the bearings.

The spring preload assembly includes a washer 23 and a preload spring 24 . The outer side of the rear bearing flange 17 of the main shaft is provided with a dense ball bearing 20, and the rear end of the dense ball bearing 20 is provided with a washer 23. The preload spring 24 is pressed against the end face of the washer 23, and the spring is in a compressed state to realize the preload of the bearing at a constant pressure. In this preload mode, the bearing preload is constant and is not easily affected by temperature, speed, etc.

The lubrication system adopts oil-air lubrication. An oil delivery pipe 13 is installed inside the electric spindle housing 1, which is connected to the oil-air lubrication inlet 7 at the rear of the shaft housing. The front bearing lock nut 18 is covered with an air seal frame 25, which is located at the front end of the front bearing 15 and connected to the oil delivery pipe 13. The air seal skeleton 25 plays the role of high-pressure gas diversion; the outer spacers 22 outside the adjacent bearings of the front and rear bearing groups are provided with radial and axial oil inlet holes 14 . The lubricating oil and compressed air are mixed in the oil delivery pipe 13 through the oil-air lubrication inlet 7 to form an oil flow, and the compressed air is used to drive the lubricating oil to flow along the wall of the oil delivery pipe, and the oil-air mixture in the oil delivery pipe 13 is sprayed onto the bearing 15 through the oil inlet hole 14 on the outer septum 22 to realize the lubrication of the bearing 15.

The coolant of the cooling system is water, and a cooling water jacket 5 is installed on the outside of the stator 4, and a water tank 12 is arranged on the outside, and the water tank 12 is connected with the coolant inlet and the coolant outlet 9 installed on the shaft housing tail cover 6. Water enters from the coolant inlet, flows into the water tank 12 on the cooling water jacket 5 outside the motor stator 4 to cool the motor, and then flows out through the coolant outlet 9, forming a circulation loop, taking away the heat generated by the motor, and reducing the temperature rise of the electric spindle and the temperature difference between the front and rear.

The front end of the front bearing flange 16 of the electric spindle is provided with a front bearing gland 26, the front end of the front bearing gland 26 is equipped with an air-tight gland 27, and the rear end of the rear bearing flange 17 is equipped with a tail baffle 28, which can effectively prevent dust from entering the front and rear bearing groups and ensure the accuracy of the front and rear bearings 15.

In the utility model, the air-sealed air inlet 10, the air-sealed skeleton 25, and the air-sealed gland 27 are the components of the air-sealed structure of the main shaft; the air-sealed structure increases the air pressure in the main shaft box through high-pressure air, so that the air in the gap of the sealing area always keeps flowing from the box to the outside of the box, preventing dust and other sundries from entering the box. Wherein, the air-sealed air inlet 10 is an air intake channel for high-pressure air, the air-sealed frame 25 plays the role of diverting the high-pressure air, and the air-sealed gland 27 can prevent dust from entering and ensure the sealing of the spindle.

Based on the high-precision internal grinding electric spindle of the present invention, by determining the raceway parameters of the bearings 15 at the front and rear ends of the spindle and the best matching parameters of the pre-tightening force, selecting bearings 15 with different channel parameters, and matching the corresponding pre-tightening force, the electric spindle can meet the high-precision requirements. The specific steps are as follows:

(1) Establish the finite element model of the main shaft-bearing rotor system;

(2) Considering the influence of bearing 15 channel parameters and preload on the rotation accuracy of the spindle, establish a simulation model for the accuracy of the electric spindle, determine the preload, the surface roundness error of the bearing 15, and the harmonic order as input conditions, and use Abaqus and Romax dynamic simulation software to calculate the radial displacement of the spindle under the simulation conditions;

(3) Establish the spindle precision optimization model, with the minimum radial displacement of the shaft end as the goal, use the optimization algorithm to match the parameters affecting the accuracy, and obtain the optimal combination of preload force, roundness error and harmonic times when the radial displacement of the spindle shaft end is minimum;

(4) Equip the electric spindle with a bearing 15 of corresponding parameters, and apply a preload of corresponding magnitude by using a preload assembly.

The above descriptions are only illustrative specific implementations of the utility model, and are not intended to limit the scope of the utility model. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the utility model shall all belong to the scope of protection of the utility model.

Claims (6)

1. A high-precision internal grinding electric spindle, characterized in that it includes a housing, a main shaft body, a rotor, a stator, a front bearing assembly, a rear bearing assembly, a spring preload assembly, a cooling system, and a lubrication system; wherein: There is a rotor in the middle of the main shaft body, a stator is arranged outside the rotor, and the stator is installed inside the housing. The front and rear ends of the main shaft body are respectively supported by the front bearing group parts and the rear bearing group parts. The front bearing group parts and the rear bearing group parts respectively include bearing groups, flanges and spacers. Set at the rear end of the dense ball bearing; The cooling system includes a cooling water jacket, a water tank, a cooling liquid inlet and a cooling liquid outlet. The cooling water jacket is arranged in the cavity between the stator and the housing, the water tank is arranged in the cooling water jacket, the cooling liquid inlet and the cooling liquid outlet are arranged on the tail cover provided on the rear end of the housing, and the water tank is connected to the cooling liquid inlet and the cooling liquid outlet; The lubrication system includes an oil delivery pipe, an oil-air lubrication inlet, an air-seal air inlet, an air-seal skeleton and an oil inlet hole. The oil delivery pipe is arranged in the casing, the oil-air lubrication inlet is arranged on the tail cover, the oil inlet hole is arranged on the septa of the front bearing assembly and the rear bearing assembly, the oil delivery pipe is connected to the oil-air lubrication inlet, the oil inlet hole and the air seal skeleton, and the air seal skeleton is set on the bearing lock nut at the front end of the main shaft body. 2. The high-precision internal grinding electric spindle according to claim 1, characterized in that: the two bearings in the bearing group are arranged in series DT, and the bearings are angular contact ball bearings. 3. The high-precision internal grinding electric spindle according to claim 1, characterized in that the spacer includes an inner spacer and an outer spacer, the inner spacer is arranged on the inner side of the two bearings, and the outer spacer is arranged on the outer side of the two bearings. 4. The high-precision internal grinding electric spindle according to claim 3, wherein the oil inlet hole includes an axial oil inlet hole and a radial oil inlet hole, and the oil inlet hole is arranged on the outer spacer. 5. The high-precision internal grinding electric spindle according to claim 1, wherein the spring preloading assembly includes a washer and a preloading spring, the washer is arranged at the rear end of the dense ball bearing, and the preloading spring presses against the end surface of the washer. 6. The high-precision internal grinding electric spindle according to claim 1, characterized in that: the front end of the flange at the front end of the main shaft body is provided with a front bearing gland, the front end of the front bearing gland is equipped with an air-tight gland, and the rear end of the flange at the rear end of the main shaft body is equipped with a tail baffle.