A permanent magnet synchronous motorized spindle

Abstract

The present application provides a permanent magnet synchronous electric spindle, which relates to the technical field of electric spindles and includes a rotor, a stator, a rotor shaft, a spindle housing and an air compressor. The rotor is mounted on the rotor shaft, and the rotor shaft is mounted inside the spindle housing. The spindle housing is a double-layer sleeve structure, including a heat-conducting inner shell and an outer shell arranged on the outer layer of the heat-conducting inner shell, and a hollow interlayer is formed between the heat-conducting inner shell and the outer shell; the side of the outer shell is provided with an air inlet that docks with the air compressor, and the inner hole of the heat-conducting inner shell is used to install the stator; the rear end of the spindle housing is provided with a guide tube for sealing the rear end of the hollow interlayer and conducting air diversion; the front end of the spindle housing is provided with a front cover, and the front cover is provided with an air outlet for discharging air in the hollow interlayer. The electric spindle provided by the present invention has high heat dissipation efficiency, can further improve the speed and processing accuracy of the electric spindle, and can adjust the heat dissipation efficiency to stabilize the working temperature of the electric spindle and increase the service life of the electric spindle.

Description

Technical Field

[0001] The present invention relates to the technical field of electric spindles, and in particular to a permanent magnet synchronous electric spindle. Background Art

[0002] The electric spindle is a new technology that has emerged in the field of CNC machine tools. It combines the machine tool spindle and spindle motor into one. It is one of the most important core components of CNC machine tools. Compared with the traditional combination of spindle motor and mechanical spindle, the electric spindle has the advantages of compact structure, light weight, small inertia, low noise, and fast response. It also has high speed, high power, simplified machine tool design, easy spindle positioning, and zero transmission of the machine tool. It is more stable during operation, and has longer precision and life. It is an ideal structure for high-speed spindle units.

[0003] Existing electric spindles are generally driven by induction motors, which have problems such as large moment of inertia, low torque density, and low control accuracy. Generally, the above problems are solved by replacing the induction motor drive in the electric spindle with a permanent magnet synchronous motor. However, electric spindles using permanent magnet synchronous motors all have the problem of heat dissipation difficulties. Permanent magnet synchronous motors generate a large amount of heat energy when working. If they cannot be cooled in time, it may cause the permanent magnet to demagnetize. Existing heat dissipation technologies include water cooling and air cooling. Electric spindles using water cooling require the installation of heat dissipation pipes in the electric spindle and external water pumps and cooling pools and other facilities. The structure is too complicated, and there is a risk of cutting fluid leakage. In addition, it is difficult to repair after the cutting fluid leaks. Electric spindles using air cooling generally install fan blades at the tail of the rotor shaft. The fan blades rotate simultaneously with the rotor shaft to cool the entire electric spindle. However, this method is less efficient and has a poor cooling effect on the front end of the electric spindle. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of heat dissipation difficulty of the electric spindle using a permanent magnet synchronous motor in the prior art, and to use a permanent magnet synchronous motor in the electric spindle, thereby reducing the rotational inertia of the electric spindle and improving the torque density and control accuracy of the electric spindle.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A permanent magnet synchronous electric spindle comprises a rotor, a stator, a rotor shaft, a spindle housing and an air compressor. The rotor is mounted on the rotor shaft, and the rotor shaft is mounted inside the spindle housing.

[0007] The main shaft housing is a double-layer sleeve structure, including a heat-conducting inner shell and an outer shell arranged on the outer layer of the heat-conducting inner shell, and a hollow interlayer is formed between the heat-conducting inner shell and the outer shell; the side of the outer shell is provided with an air inlet that docks with the air compressor, and the inner hole of the heat-conducting inner shell is used to install the stator; the rear end of the main shaft housing is provided with a guide tube for sealing the rear end of the hollow interlayer and guiding the air; the front end of the main shaft housing is provided with a front cover, and the front end cover is provided with an air outlet for discharging the air in the hollow interlayer.

[0008] The inventive principle of the present invention is as follows: In the permanent magnet synchronous electric spindle provided herein, the stator is mounted within the inner bore of a heat-conducting inner shell. The heat generated by the stator is transferred to the heat-conducting inner shell through heat exchange, which in turn transfers the heat to the air within the hollow interlayer. An air compressor compresses and pumps cold air into the hollow interlayer through an air inlet provided on the outer shell. A guide tube seals the rear end of the hollow interlayer, allowing air to exit only through the air outlet on the front cover, thereby controlling the directional flow of cold air within the hollow interlayer.

[0009] The beneficial effects of the present invention are:

[0010] (1) The present invention provides air-cooling power through an air compressor, which can dissipate heat for the entire electric spindle, and can adjust the heat dissipation efficiency by controlling the air compressor, thereby adapting to different working powers of the electric spindle, stabilizing the working temperature of the electric spindle, and improving the service life of the electric spindle.

[0011] (2) The present invention can dissipate heat and cool the entire electric spindle. The outer peripheral surface of the heat-conducting inner shell can also exchange heat for heat dissipation, resulting in a large heat dissipation contact area and high heat dissipation efficiency. The good heat dissipation performance enables the electric spindle to further increase its speed and improve machining accuracy while maintaining good temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the appearance of a permanent magnet synchronous electric spindle in one embodiment of the present invention;

[0013] Figure 2 A partial cross-sectional view of a permanent magnet synchronous electric spindle according to an embodiment of the present invention;

[0014] Figure 3 is a cross-sectional view of a spindle housing according to one embodiment of the present invention;

[0015] Figure 4 A schematic structural diagram of a spindle housing according to an embodiment of the present invention;

[0016] Figure 5 This is a schematic structural diagram of a guide tube in one embodiment of the present invention;

[0017] Figure 6This is a schematic cross-sectional installation diagram of a guide tube according to one embodiment of the present invention;

[0018] Figure 7 A front view of a front end cover according to an embodiment of the present invention;

[0019] Figure 8 For the present invention Figure 7 Cross-sectional view of section AA.

[0020] Among them, 1: rotor; 2: stator; 3: rotor shaft; 4: spindle housing; 5: air compressor; 6: guide tube; 7: front end cover; 8: tool; 9: support seat; 41: heat-conducting inner shell; 42: outer shell; 43: air inlet; 44: ribs; 45: heat dissipation fins; 61: wind shield; 71: air outlet. Implementation Method

[0021] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, and back) in the embodiments of the present invention are intended only to illustrate the relative positional relationships and movement of components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly. The connection described may be direct or indirect. In this application, the front end generally refers to the end of the electric spindle closest to the tool.

[0024] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0025] like Figures 1 to 3 As shown, in one embodiment of the present invention, a permanent magnet synchronous electric spindle is provided, including a rotor 1, a stator 2, a rotor shaft 3, a spindle housing 4 and an air compressor 5. The rotor 1 is installed on the rotor shaft 3, and the rotor shaft 3 is installed inside the spindle housing 4.

[0026] The electric spindle adjusts various speeds and torques by changing the frequency and excitation voltage of the input stator 2 winding current. The stator 2 and the rotor 1 cooperate with each other. The rotor 1 is cylindrical and has a magnet embedded therein. The inner hole of the rotor 1 is sleeved on the rotor shaft 3. Two pairs of angular contact bearings are installed at both ends of the rotor shaft 3. One pair of angular contact bearings is installed at the front end of the spindle housing 4, and the other pair of angular contact bearings is installed at the rear end of the spindle housing 4. Both ends of the rotor shaft 3 extend to the outer end of the spindle housing 4. An encoder is installed at the rear end of the rotor shaft 3 for control feedback. The front end of the rotor shaft 3 can be installed with a tool 8. The outer contour of the rear of the spindle housing 4 is fixedly connected to the support base 9 of the machine tool. The stator 2 is fixedly connected to the spindle housing 4. The three-phase wiring harness extends to the rear end of the spindle housing 4 and is connected to the cable on the support base 9 of the machine tool. The permanent magnet synchronous motor composed of the rotor 1, stator 2 and other components in this embodiment can provide high-power drive for the main shaft, has extremely strong torque and extremely high speed, and the permanent magnet synchronous motor can customize different output performance curves according to the operating conditions, such as high-speed constant power, low-speed constant power, constant torque, etc.

[0027] The spindle housing 4 is a double-layer sleeve structure, including a heat-conducting inner shell 41 and an outer shell 42 arranged on the outer layer of the heat-conducting inner shell 41, and a hollow interlayer is formed between the heat-conducting inner shell 41 and the outer shell 42; the side of the outer shell 42 is provided with an air inlet 43 connected to the air compressor 5, and the inner hole of the heat-conducting inner shell 41 is used to install the stator 2; the rear end of the spindle housing 4 is provided with a guide tube 6 for sealing the rear end of the hollow interlayer and guiding the flow; the front end of the spindle housing 4 is provided with a front cover 7, and the front cover 7 is provided with an air outlet 71 for discharging the air in the hollow interlayer.

[0028] The air compressor 5 is preferably a micro air compressor 5, and the air compressor 5, the spindle housing 4, the guide tube 6 and the front end cover 7 constitute an air-cooling heat dissipation system. The air compressor 5 provides air-cooling power, the guide tube 6 guides the fluid, the hollow interlayer of the spindle housing 4 is the place for heat exchange, and the air is finally discharged from the front end cover 7. Heat sinks can be provided in the hollow interlayer to increase the heat dissipation contact area, so that the heat dissipation efficiency is increased when the cooling air flows through. The front dust cover flow channel is preferably a converging flow channel, and the cross-section of the outlet gradually decreases, thereby increasing the air pressure in the hollow interlayer, thereby increasing the flow rate of the cooling air and improving the heat dissipation efficiency. The heat dissipation intensity of the air-cooling heat dissipation system can be controlled by the rotation speed of the air compressor 5. The micro air compressor 5 can be directly installed on one side of the electric spindle without the need for an external cooling air supply device and pipeline, which can reduce the disturbance of multiple electric spindles and improve the positioning accuracy of the electric spindle.

[0029] The stator 2 is fixed in the spindle housing 4 and in contact with the heat-conducting inner shell 41. The heat generated by the stator 2 during operation is directly transferred to the heat-conducting inner shell 41. The heat diffuses from the inside out of the heat-conducting inner shell 41, exchanging heat with the cooling air in the hollow interlayer and dissipating the heat. The cooling air then carries the heat out of the spindle housing 4. The guide tube 6 is tightly connected to the heat-conducting inner shell 41, and a sealing ring is provided at the end of the guide tube 6. The sealing ring is tightly connected to the outer shell 42, thereby sealing one end of the hollow interlayer of the spindle housing 4 and restricting the cooling air to the air outlet 71 of the front cover 7, thus completing the air diversion.

[0030] This embodiment uses air compressor 5 to provide air cooling power, which can actively dissipate heat from the entire electric spindle. The heat dissipation efficiency can be adjusted by controlling the air compressor 5 to adapt to the different operating powers of the electric spindle, stabilize the operating temperature of the electric spindle, and increase the service life of the electric spindle. The outer peripheral surface of the heat-conducting inner shell 41 of this embodiment is capable of heat exchange and heat dissipation, resulting in a large heat dissipation contact area and high heat dissipation efficiency. This excellent heat dissipation performance enables the electric spindle to further increase its speed and improve machining accuracy while maintaining good temperature control.

[0031] Furthermore, if Figure 4 As shown, in this embodiment, a plurality of ribs 44 are evenly arranged on the outer circumference of the heat-conducting inner shell 41 around its axis. The ribs 44 have an interference fit with the outer shell 42 and are used to position the outer shell 42. The outer circumference of the heat-conducting inner shell 41 is also provided with a plurality of heat dissipation fins 45. The heat dissipation fins 45 are elongated and evenly distributed between the ribs 44 and are parallel to the ribs 44.

[0032] The ribs 44, heat sink fins 45, and heat-conducting inner shell 41 are preferably integrally formed from a metal material with excellent thermal conductivity. The heat sink fins 45 increase the heat dissipation contact area, thereby increasing heat dissipation efficiency when cooling air flows through them. The ribs 44 divide the hollow interlayer into several parallel cavities. The cooling air flows in a fixed direction within each cavity, flowing from the cavity inlet to the cavity outlet parallel to the axis of the heat-conducting inner shell 41. This allows for uniform heat exchange with the four sidewalls of the cavity, improving heat dissipation uniformity.

[0033] In one embodiment, grooves equal in number to the number of ribs 44 can be machined into the inner wall of the outer shell 42, and the ribs 44 can be stuck in the corresponding grooves, thereby improving the accuracy of circumferential positioning. The number of ribs 44 can be 5, 6, 7, 8, 9, 10, 11, or 12, and the number of ribs 44 includes but is not limited to the above examples. The thickness of the ribs 44 is preferably 5-8 mm. If the width of the ribs 44 is too narrow, the support strength of the outer shell 42 will be insufficient. If the thickness of the ribs 44 is too wide, the heat dissipation area will be reduced, resulting in reduced heat dissipation efficiency. When the number of ribs 44 is large, a narrower rib 44 thickness can be selected.

[0034] like Figure 5 and Figure 6 As shown, in this embodiment, the guide tube 6 is a truncated cylindrical sleeve with a true circular front end, tightly connected to the heat-conducting inner shell 41. Specifically, the guide tube 6 engages with the heat-conducting inner shell 41 via a shoulder, and then bolts are installed in a pair of bolt holes on the guide tube 6. When the bolts are tightened, the guide tube 6 is tightly connected to the heat-conducting inner shell 41. The oblique cross-section of the guide tube 6 is elliptical, perpendicular to the axis of the guide tube 6, and extends outward to form a windshield 61. The windshield 61 has an interference fit with the inner wall of the outer shell 42. The air inlet 43 is opposite the side of the guide tube 6 where the longest generatrix is located.

[0035] Among them, the air inlet 43 is set on the outer shell 42 of the main shaft housing 4, that is, on the side of the main shaft housing 4, and the hollow interlayer is cylindrical. After the cooling air enters the hollow interlayer, it will diffuse along the hollow interlayer. The air pressure on the side of the hollow interlayer close to the air inlet 43 is relatively high, while the air pressure on the side away from the air inlet 43 is relatively low. When the flow rate of the cooling air is too fast, the above-mentioned unevenness of the air pressure will be further aggravated. If the guide tube 6 is a perfect cylindrical shape and the wind shield ring 61 is a perfect circular ring shape, the airflow in the hollow interlayer will be turbulent, and the cooling air will be unevenly distributed in the hollow interlayer, and the cooling of the surface of the heat-conducting inner shell 41 will also be uneven, which will easily lead to the problem of short service life of the heat-conducting inner shell 41. In addition, the ribs 44 evenly divide the hollow interlayer into several parallel cavities, which will aggravate the imbalance of air pressure in the hollow interlayer and cause the problem of uneven heat dissipation of the heat-conducting inner shell 41 in each cavity.

[0036] In this embodiment, a guide tube 6 is formed in the shape of a truncated cylindrical sleeve, and a windshield 61 is also elliptical. The guide tube 6 is truncated cylindrical, with each generatrix having different lengths. The side of the guide tube 6 with the longest generatrix faces the air inlet 43. This reduces the volume of the hollow interlayer away from the air inlet 43, ensuring uniform pressure of the cooling air throughout the hollow interlayer. Furthermore, the inclined windshield 61 guides the cooling air, preventing airflow disturbance within the hollow interlayer and ensuring uniform flow of cooling air into the parallel cavities within the hollow interlayer. This uniformly cools the heat-conducting inner shell 41 and improves its service life.

[0037] The outer periphery of the windshield 61 needs to contact the inner wall of the outer shell 42. To ensure a sealing effect and prevent cooling air from escaping through the gap between the windshield 61 and the outer shell 42, the outer periphery of the windshield 61 preferably needs to form an interference fit with the inner wall of the outer shell 42. To prevent the outer shell 42 from expanding due to heat during operation of the electric spindle and creating a gap between the windshield 61 and the outer shell 42, in a preferred embodiment, the outer shell 42 can be made of a material with a low thermal expansion coefficient, and the thermal expansion coefficient of the material making up the windshield 61 is greater than the thermal expansion coefficient of the outer shell 42. The windshield 61 is preferably integrally molded with the guide tube 6 to reduce air leakage between the two.

[0038] like Figure 6 As shown, in this embodiment, the included angle a between the oblique cross section 62 of the guide tube 6 and its axis is 30-60 degrees.

[0039] The angle between the oblique cross-section of the guide tube 6 and its axis can be 30 degrees, 31 degrees, 32 degrees, 33 degrees, 34 degrees, 35 degrees, 36 degrees, 37 degrees, 38 degrees, 39 degrees, 40 degrees, 41 degrees, 42 degrees, 43 degrees, 44 degrees, 45 degrees, 46 degrees, 47 degrees, 48 degrees, 49 degrees, 50 degrees, 51 degrees, 52 degrees, 53 degrees, 54 degrees, 55 degrees, 56 degrees, 57 degrees, 58 degrees, 59 degrees, or 60 degrees. Further preferably, the angle between the oblique cross-section of the guide tube 6 and its axis is 35-50 degrees. If the angle between the oblique cross-section of the guide tube 6 and its axis is too small, the overall length of the guide tube 6 is too long. If the angle between the oblique cross-section of the guide tube 6 and its axis is too large, the windshield ring 61 cannot effectively guide and stabilize the flow.

[0040] In a preferred embodiment, the cross-section of the windshield ring 61 is arc-shaped, which is any cross-section passing through the axis of the guide tube 6. The concave surface of the cross-section of the windshield ring 61 faces the direction of the heat-conducting inner shell 41, and the windshield ring 61 is made of elastic material.

[0041] Compared to the windshield 61 with an elongated cross-section, the windshield 61 in this embodiment has an arc-shaped cross-section, which allows for greater deformation margin. During operation, the air pressure in the hollow interlayer increases, exerting pressure on the windshield 61 from the heat-conducting inner shell 41 toward the rear end of the electric spindle. The greater deformation margin of the windshield 61 can reduce the possibility of air leakage. Furthermore, the concave surface of the windshield 61 faces the heat-conducting inner shell 41. During operation, the concave surface of the windshield 61 is subjected to force. Under the pressure of the cooling air, the windshield 61 undergoes a certain elastic deformation, reducing the curvature of its cross-section. The windshield 61 expands outward, increasing the extrusion force between the windshield 61 and the outer shell 42, further improving the airtightness of the windshield 61.

[0042] In this embodiment, cooling air is input into the hollow interlayer of the spindle housing 4 by the air compressor 5, and is prevented from flowing back or entering the interior of the heat-conducting inner shell 41 by the guide tube 6, so that the channel of the cooling air in the electric spindle is completely separated from the rotor, stator, bearings and other parts of the electric spindle, which can prevent the cooling air from bringing dust and other impurities in the air into the gaps between the above-mentioned parts, reduce the damage of particulate impurities to the above-mentioned parts, and improve the service life of the electric spindle.

[0043] like Figure 7 and Figure 8 As shown, in this embodiment, the rotor shaft 3 has a hollow mounting hole for mounting the tool 8 , and the air outlet 71 on the front end cover 7 is directed toward the tip cutting edge of the tool 8 .

[0044] The rotor shaft 3 is a hollow shaft, in which a tool clamping and tool changing mechanism can be installed in the hollow hole for clamping the tool 8 and quickly changing the tool. After the cooling air exchanges heat with the heat-conducting inner shell 41 in the hollow interlayer, its temperature is still much lower than the temperature of the cutting edge of the tool 8, so the cooling air can be further used to cool the cutting edge. The angle of the air outlet 71 of the front cover 7 can be determined according to the installation position of the tool 8, and the cooling air is guided to flow out of the hollow interlayer to dissipate heat from the cutting edge of the tool 8. The flow channel of the air outlet 71 of the front cover 7 is a converging type, that is, the flow channel of the air outlet 71 narrows along the direction of the air outlet, thereby increasing the flow rate of the cooling air, so that the cooling air contacts the cutting edge of the tool 8 at a higher speed, and can take away the debris generated by the processing.

[0045] In the prior art, the tool 8 of a machine tool is generally cooled by cutting fluid, which causes significant environmental pollution and is expensive. However, this embodiment cools the tool 8 by cooling air, which can reduce the environmental pollution caused by machining and also reduce machining costs.

[0046] In this embodiment, there are several air outlets 71 on the front end cover 7, which are evenly arranged around the axis of the rotor shaft 3. The rotor shaft 3 is coaxial with the spindle housing 4, and the air outlets 71 are evenly arranged around the axis of the rotor shaft 3. The cooling air flows out evenly from each air outlet 71, and does not generate radial force on the spindle housing 4 and the rotor shaft 3, thereby improving the overall stress condition of the electric spindle. The cooling air flowing out of the several air outlets 71 simultaneously generates an airflow impact on the cutting edge of the tool 8. The radial force of the impact on the tool 8 can offset each other, and will not cause radial vibration of the tool 8 due to uneven radial force, thereby improving the processing accuracy and the service life of the tool 8. In addition, the air outlets 71 are arranged around the axis of the rotor shaft 3, and no dead angle is generated, thereby promoting chip removal.

[0047] In this embodiment, the air compressor 5 is a miniature axial flow compressor. When the axial flow compressor is working, the gas is sucked in from the axial direction and discharged from the axial direction after being compressed. It is a turbine compressor. It is mainly composed of an impeller, a guide vane and a casing. The gas is sucked in from the axial direction by the high-speed rotating impeller, and the gas is discharged into the guide vane after gaining speed, and then discharged in the axial direction after being expanded. The axial flow compressor has the advantages of short airflow path, small resistance loss, large flow rate, small volume and higher efficiency than centrifugal compressors. The miniature axial flow compressor is small in size and can be directly installed on the spindle housing 4 of the electric spindle without the need to install a pipe connecting the electric spindle. In addition, the miniature axial flow compressor can provide sufficient power for the heat dissipation of the electric spindle, and the heat dissipation effect is good.

[0048] In this embodiment, the operating speed of the micro axial compressor is 0-110000RPM, the operating pressure of the axial compressor is 0-0.4Mpa, and the volume flow rate is 1-50m 3 / h.

[0049] Among them, the working pressure of the axial flow compressor can be, and the volume flow rate can be, when the working pressure of the axial flow compressor is less than 0.1Mpa, and the volume flow rate is less than 1m 3 / h, the cooling air flow rate is too slow and the heat dissipation effect is poor. When the working pressure of the axial flow compressor is greater than 0.4Mpa, or the volume flow rate is greater than 50m 3 When the cooling air flows out of the air outlet 71 at a rate of 100 rpm / h, the pressure in the hollow interlayer is too high, and the cooling air flows out of the air outlet 71 at a high speed, which easily generates a large airflow noise and affects the user experience. Compared to electric spindles that use fans or air pumps as the cooling air power source, the axial flow compressor in this embodiment can provide higher air pressure, increase the flow rate and flow rate of the cooling air, and thus improve cooling efficiency.

[0050] In this embodiment, the rotor shaft 3 is installed in the inner hole of the heat-conducting inner shell 41 through two pairs of angular contact bearings. In the axial direction of the heat-conducting inner shell 41, the two pairs of angular contact bearings are both arranged at the front end of the air inlet 43.

[0051] Heat generated by bearing friction is one of the main causes of heat generation in the electric spindle. In this embodiment, two pairs of angular contact bearings are positioned in front of the air inlet 43. This position corresponds to the hollow interlayer, which provides for more efficient heat exchange. The angular contact bearings contact the heat-conducting inner shell 41, directly transferring heat to it. In this position, the heat-conducting inner shell 41 can directly transmit heat to the hollow interlayer, where it exchanges heat with the cooling air, achieving higher heat dissipation efficiency.

[0052] Next, the heat dissipation performance of the permanent magnet synchronous electric spindle in this embodiment is verified through experiments. The parameters of the permanent magnet synchronous electric spindle used in the experiments are as follows:

[0053] The oblique cross-section of the guide tube 6 forms an angle of 45 degrees with its axis. The outer circumference of the heat-conducting inner shell 41 is evenly distributed around its axis, along with 8 ribs 44 and 40 cooling fins 45. The cooling fins 45 are evenly distributed between the ribs 44, with five cooling fins 45 positioned between every two ribs 44. The front cover 7 has eight air outlets 71, evenly spaced around the axis of the rotor shaft 3. During installation, each air outlet 71 mates with the space between two ribs 44. The electric spindle in this embodiment is mounted on the machine tool's support base 9 and electrically connected.

[0054] An encoder is installed at the rear end of the electric spindle. The encoder code disk is installed at the rear end of the rotor shaft 3 and is fixed to the rear end of the rotor shaft 3 by a top screw. It rotates with the rotor shaft 3. The encoder control board is installed on the support base 9 of the machine tool. The encoder control board reads the position of the rotor 1 when it is working. The speed and rotation angle of the electric spindle can be accurately controlled. In this embodiment, the air compressor 5 is arranged on one side of the electric spindle. Compared with the equipment in the prior art that installs the fan and the like at the rear end of the electronic shaft, the air compressor 5 in this embodiment will not affect the encoder, which can improve the control accuracy of the electric spindle.

[0055] A temperature sensor is installed in the hollow interlayer to detect the temperature of the middle section of the heat-conducting inner shell 41, and the temperature there is used to evaluate the heat dissipation performance of the permanent magnet synchronous electric spindle.

[0056] The machine tool was started without the axial-flow compressor. The electric spindle was controlled to machine a piece of aluminum alloy under different operating conditions, while the temperature of the tool tip cutting edge was monitored using an infrared thermal imager. Under high-speed, constant-power conditions, the electric spindle speed was 25,000 RPM, the middle section of the heat-conducting inner housing 41 was 83°C, and the tool tip cutting edge was 92°C.

[0057] Under the low-speed constant-power working condition, the electric spindle speed is 15000 RPM, the temperature of the middle section of the heat-conducting inner shell 41 is 80°C, and the temperature of the cutting edge of the tool tip is 125°C.

[0058] Under the condition of constant torque, the speed of the electric spindle is 8000RPM, the temperature of the middle section of the heat-conducting inner shell 41 is 72°C, and the temperature of the cutting edge of the tool tip is 86°C.

[0059] The machine tool and axial flow compressor were started simultaneously, and the electric spindle was controlled to process a piece of aluminum alloy under different working conditions. The aluminum alloy was from the same batch of aluminum alloy as the above test. At the same time, an infrared thermal imager was used to monitor the temperature of the cutting edge. Under high-speed constant power conditions, the electric spindle speed was 25,000 RPM. At this time, the machine tool adjusted the operating pressure of the axial flow compressor to 0.3 MPa and the volume flow rate to 50 m3 / s. 3 The temperature of the middle section of the heat-conducting inner shell 41 was detected to be 40°C, and the temperature of the cutting edge of the tool tip was detected to be 62°C.

[0060] Under the low-speed constant power working condition, the electric spindle speed is 15000RPM. At this time, the machine tool adjusts the working pressure of the axial flow compressor to 0.3Mpa and the volume flow rate to 50m 3 The temperature of the middle section of the heat-conducting inner shell 41 was detected to be 43°C, and the temperature of the cutting edge of the tool tip was 71°C.

[0061] Under the condition of constant torque, the electric spindle speed is 8000. At this time, the machine tool adjusts the working pressure of the axial flow compressor to 0.1Mpa and the volume flow rate to 25m 3 The temperature of the middle section of the heat-conducting inner shell 41 was detected to be 41°C, and the temperature of the cutting edge of the tool tip was 52°C.

[0062] The test results above demonstrate that, under the commonly used power-up conditions of the electric spindle, the axial-flow compressor is activated to cool the spindle. The control system adjusts the compressor's operating parameters to stabilize the temperature of the middle section of the heat-conducting inner shell 41 at around 40°C. Furthermore, after the axial-flow compressor is activated, the temperature of the tool tip cutting edge decreases significantly under all operating conditions.

[0063] In summary, this application has the following beneficial effects:

[0064] (1) The present invention provides air cooling power through the air compressor 5, which can dissipate heat for the entire electric spindle, and can adjust the heat dissipation efficiency by controlling the air compressor 5, thereby adapting to different working powers of the electric spindle, stabilizing the working temperature of the electric spindle, and improving the service life of the electric spindle.

[0065] (2) The present invention can dissipate heat and cool the entire electric spindle. The outer peripheral surface of the heat-conducting inner shell 41 can also exchange heat for heat dissipation, resulting in a large heat dissipation contact area and high heat dissipation efficiency. The good heat dissipation performance enables the electric spindle to further increase its speed and improve machining accuracy while maintaining good temperature control.

[0066] (3) In the present invention, heat dissipation fins 45 are provided on the heat-conducting inner shell 41. The heat dissipation fins 45 can increase the heat dissipation contact area and improve the heat dissipation efficiency when the cooling air flows through.

[0067] (4) The permanent magnet synchronous electric spindle provided by the present invention uses a guide tube 6 in the shape of an oblique cylindrical sleeve, and the wind shield ring 61 is also elliptical ring-shaped, which can reduce the volume of the hollow interlayer away from the air inlet 43, so that the pressure of the cooling air is uniform throughout the hollow interlayer. In addition, the inclined wind shield ring 61 can also guide the cooling air to prevent airflow turbulence in the hollow interlayer, thereby uniformly cooling the surface of the heat-conducting inner shell 41 and improving the service life of the heat-conducting inner shell 41.

[0068] (5) In the present invention, the air outlet 71 on the front end cover 7 is directed toward the cutting edge of the tool 8. The tool 8 is cooled by cooling air, which can reduce the pollution to the environment caused by mechanical processing and reduce processing costs.

[0069] (6) The micro axial flow compressor of the present invention is small in size and can be directly installed on the spindle housing 4 of the electric spindle without installing a pipe connecting the electric spindle. In addition, the micro axial flow compressor can provide sufficient power for the heat dissipation of the electric spindle, and has a good heat dissipation effect.

[0070] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A permanent magnet synchronous electric spindle, characterized in that: It comprises a rotor (1), a stator (2), a rotor shaft (3), a main shaft housing (4) and an air compressor (5), wherein the rotor (1) is mounted on the rotor shaft (3), and the rotor shaft (3) is mounted inside the main shaft housing (4) via a bearing; The spindle housing (4) is a double-layer sleeve structure, comprising a heat-conducting inner shell (41) and an outer shell (42) arranged on the outer layer of the heat-conducting inner shell (41), wherein a hollow interlayer is formed between the heat-conducting inner shell (41) and the outer shell (42); an air inlet (43) for docking with the air compressor (5) is provided on the side of the outer shell (42), and the inner hole of the heat-conducting inner shell (41) is used to install the stator (2); a guide tube (6) is provided at the rear end of the spindle housing (4) for sealing the rear end of the hollow interlayer and conducting air diversion; a front end cover (7) is provided at the front end of the spindle housing (4), and an air outlet (71) is provided on the front end cover (7) for discharging air in the hollow interlayer; The guide tube (6) is a truncated cylindrical sleeve, and the front end of the guide tube (6) is a perfect circular ring, which is tightly connected to the heat-conducting inner shell (41); the oblique cross-section of the guide tube (6) is an elliptical ring, and the oblique cross-section is perpendicular to the axis of the guide tube (6) and extends a wind shield ring (61) in all directions, and the wind shield ring (61) is interference-fitted with the inner wall of the outer shell (42); the air inlet (43) is opposite to the side where the longest busbar of the guide tube (6) is located.

2. The permanent magnet synchronous electric spindle according to claim 1, characterized in that: A plurality of ribs (44) are evenly arranged on the outer peripheral surface of the heat-conducting inner shell (41) around its axis. The ribs (44) are interference-fitted with the outer shell (42) and are used to position the outer shell (42). A plurality of heat dissipation fins (45) are also arranged on the outer peripheral surface of the heat-conducting inner shell (41). The heat dissipation fins (45) are long strips and evenly distributed between the ribs (44) and are parallel to the ribs (44).

3. The permanent magnet synchronous electric spindle according to claim 1, characterized in that: The included angle between the oblique cross section of the guide tube (6) and its axis is 30-60 degrees.

4. The permanent magnet synchronous electric spindle according to claim 1, characterized in that: The cross section of the windshield ring (61) is arc-shaped, and the cross section is any cross section passing through the axis of the guide tube (6). The concave surface of the cross section of the windshield ring (61) faces the direction of the heat-conducting inner shell (41). The windshield ring (61) is made of elastic material.

5. The permanent magnet synchronous electric spindle according to claim 1, characterized in that: The rotor shaft (3) has a hollow mounting hole for mounting a tool (8), and the air outlet (71) on the front end cover (7) is oriented toward the tip cutting edge of the tool (8).

6. The permanent magnet synchronous electric spindle according to claim 5, characterized in that: There are a plurality of air outlets (71) on the front end cover (7), which are evenly arranged around the axis of the rotor shaft (3).

7. The permanent magnet synchronous electric spindle according to claim 1, characterized in that: The air compressor (5) is a miniature axial flow compressor.

8. The permanent magnet synchronous electric spindle according to claim 7, characterized in that: The operating speed of the micro axial compressor is 0-110000RPM, the pressure is 0-0.4Mpa, and the volume flow rate is 1-50m 3 / h.

9. The permanent magnet synchronous electric spindle according to claim 1, characterized in that: The rotor shaft (3) is mounted in the inner hole of the heat-conducting inner shell (41) via two pairs of angular contact bearings, and the two pairs of angular contact bearings are both arranged at the downwind position of the air inlet (43).

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