A radial-axial composite magnetic loading device for online testing of mechanical parameters of high-speed electric spindles.

Abstract

A radial-axial composite magnetic loading device for online testing of the mechanical parameters of high-speed electric spindles solves the problem of existing technologies that can only test torque and cannot test radial and axial forces. It includes an upper connecting body housing connected to the end of the electric spindle, a radial loading housing at one end of the upper connecting body housing, and an axial loading housing at the other end of the radial loading housing. Inside the housing, one end of a test rod is connected to the electric spindle, and the other end of the test rod has a lower axial loading section and an axial displacement sensor. A middle radial loading section is located in the middle of the test rod, and upper and lower radial displacement detection components are respectively located at both ends of the test rod. Its design is reasonable and compact, enabling dynamic load simulation of high-speed electric spindles, online testing of the mechanical parameters of high-speed electric spindles, and stable loading over long periods during testing, providing an experimental method for dynamic performance testing of machine tool electric spindles.

Description

Technical Field

[0001] This invention belongs to the field of high-speed electric spindle performance testing technology, specifically relating to a radial-axial composite magnetic loading device for online testing of the mechanical parameters of a high-speed electric spindle. Background Technology

[0002] Currently, the requirements for machining accuracy, efficiency, and stability of machine tools, which serve as the mother machines of industry, are gradually increasing, making CNC machine tools a key tool in my country's equipment manufacturing industry. As a core component of CNC machine tools, the performance of the high-speed electric spindle directly determines the accuracy, performance, and machining quality of the entire system. During actual operation, the electric spindle drives the tool holder to cut the workpiece. The forces acting on the electric spindle include radial and axial forces from the tool holder feed. However, existing electric spindle testing systems, including motor-related testing systems, mostly only test torque and cannot test radial and axial force performance. Therefore, it is necessary to improve the existing performance testing devices for high-speed electric spindles. Summary of the Invention

[0003] This invention addresses the aforementioned problems by providing a radial-axial composite magnetic loading device for online testing of the mechanical parameters of high-speed electric spindles. This device enables dynamic load simulation of high-speed electric spindles and allows for online testing of their radial loading working stiffness, axial loading working stiffness, static stiffness, dynamic stiffness, modal parameters, rotational characteristics, and other mechanical parameters. It also provides an experimental means for testing the dynamic performance of machine tool electric spindles by ensuring stable loading over extended periods.

[0004] The technical solution adopted in this invention is as follows: the radial-axial composite magnetic loading device for online testing of the mechanical parameters of a high-speed electric spindle includes an upper connecting body housing connected to the spindle end cap at the end of the electric spindle. The upper connecting body housing has a radial loading housing at one end and an axial loading housing at the other end. A test rod is also provided inside the upper connecting body housing, the radial loading housing, and the axial loading housing. One end of the test rod is connected to a pull claw structure inside the electric spindle via a pull stud. The other end of the test rod has a lower axial loading part and an axial displacement sensor. A middle radial loading part is provided in the middle of the test rod. An upper radial displacement detection component is provided inside the upper connecting body housing, and a lower radial displacement detection component is provided at the lower end inside the radial loading housing. The test rod, the lower axial loading part, and the middle radial loading part are all arranged coaxially with the electric spindle.

[0005] The lower axial loading section includes an axial loading disk disposed at the lower end of the test bar. An axial electromagnet is disposed between the axial loading disk and the lower end of the radial loading housing. The axial electromagnet is non-contactly sleeved on the outside of the lower end of the test bar, and there is a gap between the axial electromagnet and the axial loading disk. A hollow shaft incremental encoder is also disposed between the axial loading disk and the lower end of the axial loading housing, and the axial displacement sensor is disposed at the lower end of the axial loading housing, with the probe of the axial displacement sensor close to the end face of the axial loading disk. When the coil of the axial electromagnet is energized, a closed magnetic field is formed between the axial electromagnet, the gap, and the axial loading disk, thereby generating an axial magnetic force Fa between the axial electromagnet and the axial loading disk, simulating the axial cutting force experienced by the machine tool spindle in actual cutting.

[0006] The intermediate radial loading section includes a silicon steel sleeve fitted around the outer side of the middle part of the test rod. A radial electromagnet is also fitted around the outside of the silicon steel sleeve, and there is a uniform gap between the inner ring of the radial electromagnet and the outer wall of the silicon steel sleeve. When the coil of the radial electromagnet is energized, a closed magnetic field is formed between the radial electromagnet, the gap, and the silicon steel sleeve, thereby generating a radial magnetic force Fr between the radial electromagnet and the test rod, simulating the radial cutting force experienced by the machine tool spindle during actual cutting.

[0007] A cooling water jacket is provided between the outer ring of the radial electromagnet and the inner wall of the radial loading housing. A cooling water channel is formed between the cooling water tank on the outer side of the cooling water jacket and the inner wall of the radial loading housing, and a sealing ring is provided between the cooling water jacket and the radial loading housing. A cooling water inlet and a cooling water outlet are provided on the outer wall of the radial loading housing, and the cooling water inlet and outlet are respectively connected to the cooling water channel. This allows cooling water to flow into the cooling water channel through the cooling water inlet and out through the cooling water outlet, thereby using the circulating cooling water to cool the entire device. This achieves long-term stable loading of the device without introducing other heat sources, ensuring the testing accuracy of the electric spindle.

[0008] The upper radial displacement detection assembly includes an upper radial displacement detection annular base with a socket hole in the middle, and several sets of upper radial displacement sensors are arranged on the outer circumference of the upper radial displacement detection annular base. The lower radial displacement detection assembly includes a lower radial displacement detection annular base with a socket hole in the middle, and several sets of lower radial displacement sensors are arranged on the outer circumference of the lower radial displacement detection annular base. The upper and lower radial displacement detection assemblies are respectively fitted onto the corresponding detection positions at the upper and lower ends of the test rod through the socket hole in the middle.

[0009] The upper radial displacement detection annular base and the lower radial displacement detection annular base have the same structure, both including an annular base body. A socket hole is provided in the middle of the annular base body, and several sets of equally spaced displacement sensor mounting slots are provided on the outer circumference of the annular base body. The upper and lower radial displacement sensors are respectively installed in the displacement sensor mounting slots. The annular base body also has several base fixing holes arranged along the same circumference. This allows the upper and lower radial displacement sensors to be arranged in their respective displacement sensor mounting slots, and the base fixing holes facilitate the installation and connection of the radial displacement detection annular base.

[0010] The bottom of the displacement sensor mounting slot is provided with a sensor base insertion hole, into which a sensor mounting base is inserted. The sensor mounting base includes a mounting base body, with a positioning flange at the upper end and an eccentric mounting hole in the middle. An auxiliary mounting countersunk hole is located at the upper end of the eccentric mounting hole. Mounting plates are also provided on both sides of the sensor mounting base, and these plates are connected to the fixing screw holes at the bottom of the displacement sensor mounting slot via connecting bolts. This allows an upper radial displacement sensor or a lower radial displacement sensor to be installed in the eccentric mounting hole of the sensor mounting base. By rotating the sensor mounting base with the eccentric mounting hole within the sensor base insertion hole, the radial displacement sensor can be moved a certain distance in the Z direction, thereby precisely adjusting the position of the displacement sensor.

[0011] The upper radial displacement detection assembly is equipped with two sets of upper radial displacement sensors, arranged at a 90-degree angle on the outer circumference of the upper radial displacement detection annular base. The probes of the upper radial displacement sensors are close to the cylindrical surface on the outer side of the upper end of the test rod, ensuring that the direction of displacement measurement is consistent with the direction of the radial force acting on the test rod. The upper end of the test rod is measured using the two sets of upper radial displacement sensors arranged at a 90-degree angle on the upper radial displacement detection annular base. The measured signal is the displacement or vibration signal of the electric spindle at that measurement position under radial force or sinusoidal excitation, thereby measuring the tilt angle of the test rod.

[0012] The lower radial displacement detection assembly is equipped with four sets of lower radial displacement sensors. Two sets of sensors are arranged at a 90-degree angle on the outer circumference of the lower radial displacement detection annular base, ensuring that the direction of displacement measurement is consistent with the direction of the radial force on the test rod. The other two sets of sensors are installed at angles selected according to weights. The probes of the lower radial displacement sensors are close to the cylindrical surface on the outer side of the lower end of the test rod. The lower end of the test rod is measured by the four sets of lower radial displacement sensors on the lower radial displacement detection annular base. The measured signal is the displacement or vibration signal of the electric spindle at the measurement position under radial force or sinusoidal excitation. Thus, the roundness error, rotation error, and eccentricity error of the test rod can be separated using the principle of Fourier transform.

[0013] The displacement sensors of the upper radial displacement detection component, the lower radial displacement detection component, and the axial displacement sensor are electrically connected to a charge amplifier. The charge amplifier is electrically connected to a data acquisition module, which is electrically connected to a mobile workstation. The mobile workstation is also electrically connected to a signal output module, which is electrically connected to a pulse width modulation amplifier. The pulse width modulation amplifier is electrically connected to the electromagnets of the intermediate radial loading section and the lower axial loading section, respectively. Furthermore, the mobile workstation is electrically connected to the signal input terminal of the frequency converter via an A / D converter, and the signal output terminal of the frequency converter is electrically connected to the control terminal of the electric spindle. This allows the mobile workstation to analyze and process the displacement signals collected from the displacement sensors of the upper radial displacement detection component, the lower radial displacement detection component, and the axial displacement sensor, thereby enabling online simulation of the dynamic load of the high-speed electric spindle and testing of mechanical parameters such as radial loading working stiffness, axial loading working stiffness, static stiffness, dynamic stiffness, modal parameters, and rotational characteristics of the high-speed electric spindle.

[0014] The beneficial effects of this invention are as follows: This invention employs an upper connecting body housing connected to the spindle end cap at the end of the electric spindle. The upper connecting body housing has a radial loading housing at one end, and an axial loading housing at the other end. A test rod is also provided inside the upper connecting body housing, the radial loading housing, and the axial loading housing. One end of the test rod is connected to a pull claw structure inside the electric spindle, and the other end of the test rod has a lower axial loading part and an axial displacement sensor. A middle radial loading part is provided in the middle of the test rod. An upper radial displacement detection assembly is provided inside the upper connecting body housing. The radial loading housing contains… The structure, with a lower radial displacement detection component at the bottom, is rationally designed and compact. It can simulate the actual cutting process of a machine tool, applying a controllable radial / axial / composite non-contact loading force to the electric spindle. This enables dynamic load simulation of the high-speed electric spindle and allows for online testing of mechanical parameters such as radial loading working stiffness, axial loading working stiffness, static stiffness, dynamic stiffness, modal parameters, and rotational characteristics. Furthermore, it can maintain stable loading for extended periods during testing, providing an experimental method for testing the dynamic performance of machine tool electric spindles. It exhibits high versatility across various machine tools and offers significant economic benefits. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of one structure of the present invention.

[0016] Figure 2 yes Figure 1 A schematic diagram of the structure of the upper radial displacement detection component.

[0017] Figure 3 yes Figure 1 A schematic diagram of a lower radial displacement detection component.

[0018] Figure 4 yes Figure 3 A bottom view.

[0019] Figure 5 yes Figure 2 The upper radial displacement detection ring base (or Figure 3 A schematic diagram of a structure of a ring base for detecting lower radial displacement.

[0020] Figure 6 yes Figure 5 Top view.

[0021] Figure 7 yes Figure 2 and Figure 3 A schematic diagram of a sensor mounting base.

[0022] Figure 8 yes Figure 7 Top view.

[0023] Figure 9 yes Figure 1 A schematic diagram of a connection structure between a radially loaded housing and a cooling water jacket.

[0024] Figure 10 This is a schematic block diagram showing a connection between the radial electromagnet of the intermediate radial loading section of the present invention and the pulse width modulation amplifier, the signal output module, and the mobile workstation.

[0025] Figure 11 This is a schematic block diagram showing a connection between the axial electromagnet of the lower axial loading part of the present invention and the pulse width modulation amplifier, signal output module and mobile workstation.

[0026] Figure 12 This is a control principle block diagram of the present invention.

[0027] Explanation of the numbers in the diagram: 1. Housing; 2. Electric spindle; 3. Spindle end cover; 4. Upper connecting body housing; 5. Upper radial displacement detection assembly; 6. Test bar; 7. Intermediate radial loading part; 8. Radial loading housing; 9. Lower radial displacement detection assembly; 10. Axial loading housing; 11. Lower axial loading part; 12. Axial displacement sensor; 13. Hollow shaft incremental encoder; 14. Axial loading disk; 15. Axial electromagnet; 16. Protective sleeve; 17. Silicon steel sleeve; 18. Cooling water jacket; 19. Radial electromagnet; 20. Intermediate body spacer ring; 21. Intermediate body end cover; 22. Upper connecting body end cover; 23. Upper connecting body spacer ring; 24. Pull stud; 25. Upper radial displacement detection ring base; 2 6. Socket hole, 27. Sensor mounting base, 28. Upper radial displacement sensor, 29. Mounting base pressure plate, 30. Lower radial displacement detection ring base, 31. Lower radial displacement sensor, 32. Ring base body, 33. Displacement sensor mounting slot, 34. Base fixing hole, 35. Sensor seat insertion through hole, 36. Pressure plate fixing screw hole, 37. Mounting mating stop, 38. Mounting base body, 39. Positioning flange, 40. Eccentric mounting hole, 41. Auxiliary mounting countersunk hole, 42. Cooling water inlet, 43. Lock nut straight connector, 44. Cooling water channel, 45. Cooling water outlet, 46. Sealing ring, 47. Mobile workstation, 48. Signal output module, 49. Pulse width modulation amplifier. Detailed Implementation

[0028] according to Figures 1-11The specific structure of this invention is described in detail below. This online testing device for the mechanical parameters of a high-speed electric spindle, comprising a radial and axial composite magnetic loading mechanism, includes an upper connecting housing 4, which is connected to the spindle end cap 3 at the lower end of the electric spindle 2. The electric spindle 2 is connected to the machine tool via a housing 1. A radial loading housing 8 is located at the lower end of the upper connecting housing 4, and an axial loading housing 10 is also located at the lower end of the radial loading housing 8. A columnar test rod 6 is disposed inside the coaxially arranged upper connecting housing 4, radial loading housing 8, and axial loading housing 10. One end of the test rod 6 is connected to a pull claw structure inside the electric spindle 2 via a pull stud 24. The other end of the test rod 6, inside the axial loading housing 10, is provided with a lower axial loading part 11 and an axial displacement sensor 12.

[0029] The lower axial loading part 11 includes an axial loading disk 14 disposed at the lower end of the test rod 6. An axial electromagnet 15 is disposed between the axial loading disk 14 and the lower end of the radial loading housing 8. The loading surface of the axial electromagnet 15 is flat. The axial electromagnet 15 is non-contactly sleeved on the outside of the lower end of the test rod 6, and there is a certain gap (e.g., 0.5 mm) between the axial loading disk 14 and the lower end of the axial loading housing 10. A hollow shaft incremental encoder 13 for counting is also disposed between the axial loading disk 14 and the lower end of the axial loading housing 10 to record the total number of points collected by the sensor. An axial displacement sensor 12 is disposed at the lower end of the axial loading housing 10, and the probe of the axial displacement sensor 12 is close to the end face of the axial loading disk 14. Therefore, when the coil of the axial electromagnet 15 is energized, a closed magnetic field is formed between the axial electromagnet 15, the gap, and the axial loading disk 14, thereby generating an axial magnetic force Fa between the axial electromagnet 15 and the axial loading disk 14, simulating the axial cutting force experienced by the machine tool spindle in actual cutting.

[0030] A central radial loading section 7 is provided inside the radial loading housing 8 at the middle of the test rod 6. The test rod 6, the lower axial loading section 11, and the central radial loading section 7 are all arranged coaxially with the electric spindle 2. The central radial loading section 7 includes a silicon steel sleeve 17 fitted on the outer side of the middle of the test rod 6, and a protective sleeve 16 fitted on the lower side of the test rod 6 below the silicon steel sleeve 17. Furthermore, a radial electromagnet 19 is fitted on the outside of the silicon steel sleeve 17. The loading surface of the radial electromagnet 19 is an inner arc surface with a certain curvature, and there is a uniform gap (e.g., a spacing of 0.4 mm) between the inner ring of the radial electromagnet 19 and the outer wall of the silicon steel sleeve 17. An intermediate end cap 21 is provided above the radial electromagnet 19 at the upper end of the radial loading housing 8, and an intermediate spacer ring 20 is also provided between the intermediate end cap 21 and the radial electromagnet 19. When the coil of the radial electromagnet 19 is energized, a closed magnetic field is formed between the radial electromagnet 19, the gap, and the silicon steel sleeve 17, thereby generating a radial magnetic force Fr between the radial electromagnet 19 and the test rod 6, simulating the radial cutting force experienced by the machine tool spindle during actual cutting. Due to the eddy current effect generated within the changing magnetic field, eddy currents will form on the force-bearing surface of the radial electromagnet 19. The magnetic field formed by the eddy currents not only weakens the original magnetic field, but its thermal effect also limits the rotational speed of the radial electromagnet 19. Furthermore, the magnetic field becomes unstable in high-temperature environments, and the magnetic material may suddenly lose its magnetism. Considering all these reasons, the force-bearing surface of the radial electromagnet 19 core is made of stacked silicon steel sheets, with the steel sheets insulated from each other.

[0031] A cooling water jacket 18 is provided between the outer ring of the radial electromagnet 19 and the inner wall of the radial loading housing 8. A cooling water channel 44 is formed between the cooling water tank on the outside of the cooling water jacket 18 and the inner wall of the radial loading housing 8, and a sealing ring 46 is provided between the cooling water jacket 18 and the radial loading housing 8. A cooling water inlet 42 and a cooling water outlet 45 are provided on the outer wall of the radial loading housing 8, and the cooling water inlet 42 and the cooling water outlet 45 are respectively connected to the cooling water channel 44; and a lock nut straight-through connector 43 is also provided on the cooling water inlet 42 and the cooling water outlet 45 respectively. Thus, cooling water flows into the cooling water channel 44 through the cooling water inlet 42 and flows out from the cooling water outlet 45, thereby using the circulating cooling water to cool the entire device, so as to achieve long-term stable loading of the device without introducing other heat sources and ensuring the testing accuracy of the electric spindle 2.

[0032] An upper radial displacement detection assembly 5 is disposed inside the upper connecting body housing 4, and an upper connecting body end cap 22 is disposed at the lower end of the upper connecting body housing 4. An upper connecting body spacer ring 23 is also disposed between the upper radial displacement detection assembly 5 and the upper connecting body end cap 22. A lower radial displacement detection assembly 9 is disposed at the lower end of the interior of the radial loading housing 8. The upper radial displacement detection assembly 5 includes an upper radial displacement detection annular base 25, a socket hole 26 is disposed in the middle of the upper radial displacement detection annular base 25, and several sets of upper radial displacement sensors 28 are disposed on the outer circumference of the upper radial displacement detection annular base 25. At the same time, the lower radial displacement detection assembly 9 includes a lower radial displacement detection annular base 30, a socket hole 26 is disposed in the middle of the lower radial displacement detection annular base 30, and several sets of lower radial displacement sensors 31 are disposed on the outer circumference of the lower radial displacement detection annular base 30. Then, the upper radial displacement detection component 5 and the lower radial displacement detection component 9 are respectively fitted onto the corresponding detection positions at the upper and lower ends of the test rod 6 through the central socket 26.

[0033] The upper radial displacement detection annular base 25 of the upper radial displacement detection assembly 5 and the lower radial displacement detection annular base 30 of the lower radial displacement detection assembly 9 have the same structure, both including an annular base body 32. The annular base body 32 has a socket hole 26 in the middle, and the upper and lower sides of the annular base body 32 are respectively provided with mounting fit stop 37 for interconnection with the upper and lower structures. The outer circumference of the annular base body 32 is provided with several sets of displacement sensor mounting slots 33 arranged at equal intervals. The upper radial displacement sensor 28 and the lower radial displacement sensor 31 are respectively installed in the displacement sensor mounting slots 33. The annular base body 32 is also provided with several base fixing holes 34 arranged along the same circumference to arrange the upper radial displacement sensor 28 and the lower radial displacement sensor 31 in the corresponding displacement sensor mounting slots 33, and to facilitate the installation and connection of the radial displacement detection annular base using the base fixing holes 34.

[0034] In addition, a sensor mounting groove 33 is provided at the bottom of the displacement sensor mounting groove 33 on the outer circumference of the annular base body 32, and a sensor mounting base 27 is inserted into the sensor mounting groove 35. The sensor mounting base 27 includes a mounting base body 38, a positioning flange 39 is provided at the upper end of the mounting base body 38, an eccentric mounting hole 40 is provided in the middle of the mounting base body 38, and an auxiliary mounting countersunk hole 41 is provided at the upper end of the eccentric mounting hole 40. Mounting base pressure plates 29 are provided on both sides of the sensor mounting base 27, and the mounting base pressure plates 29 are connected to the pressure plate fixing screw holes 36 provided at the bottom of the displacement sensor mounting groove 33 by connecting bolts. Thus, the upper radial displacement sensor 28 or the lower radial displacement sensor 31 is installed in the eccentric mounting hole 40 of the sensor mounting base 27, and the sensor mounting base 27 with the eccentric mounting hole 40 is rotated in the sensor seat insertion through hole 35 so that the radial displacement sensor on it can move a certain distance in the Z direction (for example, move a distance of 3mm in the Z direction) to precisely adjust the position of the displacement sensor.

[0035] The upper radial displacement detection assembly 5 has two sets of upper radial displacement sensors 28 installed on the upper radial displacement detection annular base 25. The two sets of upper radial displacement sensors 28 are arranged at a 90-degree angle on the outer circumference of the upper radial displacement detection annular base 25. The probes of the upper radial displacement sensors 28 are close to the cylindrical surface on the outer side of the upper end of the test rod 6, and the direction of displacement measurement is consistent with the direction of the radial force on the test rod 6. The upper end of the test rod 6 is measured by using the two sets of upper radial displacement sensors 28 arranged at a 90-degree angle on the upper radial displacement detection annular base 25. The measured signal is the displacement or vibration signal of the electric spindle 2 at the measurement position under the action of radial force or sinusoidal excitation, and then the tilt angle of the test rod 6 is measured.

[0036] The lower radial displacement detection assembly 9 has four sets of lower radial displacement sensors 31 mounted on its lower radial displacement detection annular base 30. Two sets of sensors 31 are arranged at a 90-degree angle on the outer circumference of the base 30, ensuring that the direction of displacement measurement is consistent with the direction of the radial force on the test rod 6. The other two sets of sensors 31 are installed at angles selected according to weights; that is, two sets of sensors 31 are at the same angular position as the two sets of upper radial displacement sensors 28 above them, while the other two sets are set at 180° and 270° respectively. The probes of the lower radial displacement sensors 31 are close to the cylindrical surface of the outer protective sleeve 16 at the lower end of the test rod 6. Therefore, the protective sleeve 16 on the lower outer side of the test rod 6 is measured by four sets of lower radial displacement sensors 31 set on the lower radial displacement detection ring base 30. The measured signal is the displacement or vibration signal of the electric spindle 2 at the measurement position under radial force or sinusoidal excitation. Then, the roundness error, rotation error and eccentricity error of the test rod 6 are separated by the principle of Fourier transform.

[0037] The two sets of upper radial displacement sensors 28 on the upper radial displacement detection assembly 5, the four sets of lower radial displacement sensors 31 on the lower radial displacement detection assembly 9, and the axial displacement sensor 12 are electrically connected to a charge amplifier. The charge amplifier is electrically connected to a data acquisition module, which is electrically connected to a mobile workstation 47. The mobile workstation 47 is also electrically connected to a signal output module 48, which is electrically connected to a pulse width modulation amplifier 49. The pulse width modulation amplifier 49 is electrically connected to the radial electromagnet 19 of the intermediate radial loading section 7 and the axial electromagnet 15 of the lower axial loading section 11. Furthermore, the mobile workstation 47 is electrically connected to the signal input terminal of the frequency converter via an A / D converter, and the signal output terminal of the frequency converter is electrically connected to the control terminal of the electric spindle 2. Thus, the mobile workstation 47 analyzes and processes the displacement signals collected from the displacement sensors of the upper radial displacement detection component 5, the lower radial displacement detection component 9, and the axial displacement sensor 12, thereby realizing online simulation of the dynamic load of the high-speed electric spindle 2, as well as testing of the mechanical parameters of the high-speed electric spindle 2, such as radial loading working stiffness, axial loading working stiffness, static stiffness, dynamic stiffness, modal parameters, and rotational characteristics.

[0038] When using this online testing device for the mechanical parameters of a high-speed electric spindle, the power supply to the electric spindle 2 is first turned on, allowing the electric spindle 2 to enter a high-speed rotation state. The signal output module 48 is controlled by the moving workstation 47 to output a loading signal. The loading signal is amplified by the pulse width modulation amplifier 49 and then input to the excitation coils of the radial electromagnet 19 and the axial electromagnet 15. Furthermore, during the high-speed rotation of the electric spindle 2, the magnetic field strength in the silicon steel sleeve 17 of the intermediate radial loading part 7 and the axial loading disk 14 of the lower axial loading part 11 will change periodically. The changing magnetic field causes eddy current magnetic fields to be generated inside the silicon steel sleeve 17 and the axial loading disk 14, which in turn affects the magnetic field in the air gap (gap), thereby causing the test rod 6 to bear a certain magnitude of radial force, axial force, or sinusoidal excitation force of a certain frequency according to the control signal. Subsequently, the upper radial displacement sensor 28, the lower radial displacement sensor 31, and the axial displacement sensor 12 transmit the displacement / vibration signals of the electric spindle 2 under certain radial force, axial force, or sinusoidal excitation conditions to the mobile workstation 47 via a charge amplifier and a data acquisition module. The mobile workstation 47 analyzes and processes the received force and displacement / vibration signals to obtain parameters such as the radial loading working stiffness curve, axial stiffness curve, modal parameters, and rotational characteristics of the electric spindle 2 under high-speed rotation.

[0039] Meanwhile, to enable the test rod 6 to generate magnetic force between itself and the various magnetic loading devices, the test rod 6 can be made of ferromagnetic materials such as iron, cobalt, nickel, or their alloys. Furthermore, a standard inspection mandrel, i.e., the test rod 6, can be selected according to different spindle types. Common types include BT, HSK, and SK; for example, a BT40 inspection mandrel can be used. The test rod 6 is required to have high roundness and concentricity. In actual use, the test rod 6 cannot be a perfect cylinder; it will always have a certain degree of surface unevenness, and there will always be a certain rotational error during actual rotation. The unique structure designed in this invention can effectively solve these problems that cause measurement errors during the testing process.

[0040] Furthermore, to reduce the impact of machine tool spindle thermal stress on the experimental results, the machine tool spindle needs to be preheated by idling for about 30 minutes before data measurement. In static mode, the device can generate a radial force of ±1000N and an axial force of 600N, while in dynamic mode at a frequency of 1000Hz, it can generate a dynamic load of ±300N, enabling high-frequency loading of the high-speed electric spindle 2 under relatively large loading forces.

Claims

1. A radial-axial composite magnetic loading device for online testing of mechanical parameters of a high-speed electric spindle, comprising an upper connecting body housing (4) connected to the spindle end cap (3) at the end of the electric spindle (2), characterized in that: The upper connecting body housing (4) is provided with a radial loading housing (8) at one end, and an axial loading housing (10) is provided at the other end of the radial loading housing (8). A test rod (6) is also provided inside the upper connecting body housing (4), the radial loading housing (8) and the axial loading housing (10). One end of the test rod (6) is connected to the pull claw structure inside the electric spindle (2) through a pull stud (24). The other end of the test rod (6) is provided with a lower axial loading part (11) and an axial displacement sensor (12). A middle radial loading part (7) is provided in the middle of the test rod (6). An upper radial displacement detection component (5) is provided inside the upper connecting body housing (4). A lower radial displacement detection component (9) is provided at the lower end inside the radial loading housing (8). The test rod (6), the lower axial loading part (11) and the middle radial loading part (7) are all arranged coaxially with the electric spindle (2). The lower axial loading part (11) includes an axial loading disk (14) disposed at the lower end of the test rod (6). An axial electromagnet (15) is disposed between the axial loading disk (14) and the lower end of the radial loading housing (8). The axial electromagnet (15) is non-contactly sleeved on the outside of the lower end of the test rod (6). There is a gap between the axial electromagnet (15) and the axial loading disk (14). A hollow shaft incremental encoder (13) is also disposed between the axial loading disk (14) and the lower end of the axial loading housing (10). The axial displacement sensor (12) is disposed at the lower end of the axial loading housing (10). The probe of the axial displacement sensor (12) is close to the end face of the axial loading disk (14). The intermediate radial loading part (7) includes a silicon steel sleeve (17) sleeved on the outer side of the middle part of the test rod (6). A radial electromagnet (19) is also sleeved on the outside of the silicon steel sleeve (17). There is a uniform gap between the inner ring of the radial electromagnet (19) and the outer wall of the silicon steel sleeve (17). The upper radial displacement detection assembly (5) includes an upper radial displacement detection annular base (25), with a socket hole (26) in the middle of the upper radial displacement detection annular base (25), and several sets of upper radial displacement sensors (28) are arranged on the outer circumference of the upper radial displacement detection annular base (25); the lower radial displacement detection assembly (9) includes a lower radial displacement detection annular base (30), with a socket hole (26) in the middle of the lower radial displacement detection annular base (30), and several sets of lower radial displacement sensors (31) are arranged on the outer circumference of the lower radial displacement detection annular base (30).

2. The radial-axial composite magnetic loading device for online testing of mechanical parameters of high-speed electric spindles according to claim 1, characterized in that: A cooling water jacket (18) is provided between the outer ring of the radial electromagnet (19) and the inner wall of the radial loading housing (8). A cooling water channel (44) is formed between the cooling water tank on the outside of the cooling water jacket (18) and the inner wall of the radial loading housing (8). A sealing ring (46) is provided between the cooling water jacket (18) and the radial loading housing (8). A cooling water inlet (42) and a cooling water outlet (45) are provided on the outer wall of the radial loading housing (8). The cooling water inlet (42) and the cooling water outlet (45) are respectively connected to the cooling water channel (44).

3. The radial-axial composite magnetic loading device for online testing of mechanical parameters of high-speed electric spindles according to claim 1, characterized in that: The upper radial displacement detection annular base (25) and the lower radial displacement detection annular base (30) have the same structure, both including an annular base body (32). A socket hole (26) is provided in the middle of the annular base body (32), and several groups of equally spaced displacement sensor mounting slots (33) are provided on the outer circumference of the annular base body (32). The upper radial displacement sensor (28) and the lower radial displacement sensor (31) are respectively installed in the displacement sensor mounting slots (33). Several base fixing holes (34) arranged along the same circumference are also provided on the annular base body (32).

4. The radial-axial composite magnetic loading device for online testing of mechanical parameters of high-speed electric spindles according to claim 3, characterized in that: The bottom of the displacement sensor mounting groove (33) is provided with a sensor seat insertion through hole (35), and a sensor mounting base (27) is inserted into the sensor seat insertion through hole (35). The sensor mounting base (27) includes a mounting base body (38), the upper end of the mounting base body (38) is provided with a positioning flange (39), the middle part of the mounting base body (38) is provided with an eccentric mounting hole (40), and the upper end of the eccentric mounting hole (40) is provided with an auxiliary mounting countersunk hole (41). Mounting base pressure plates (29) are also provided on both sides of the sensor mounting base (27), and the mounting base pressure plates (29) are connected to the pressure plate fixing screw holes (36) provided at the bottom of the displacement sensor mounting groove (33) by connecting bolts.

5. The radial-axial composite magnetic loading device for online testing of mechanical parameters of high-speed electric spindles according to claim 1, characterized in that: The upper radial displacement detection assembly (5) is equipped with two sets of upper radial displacement sensors (28). The two sets of upper radial displacement sensors (28) are arranged at a 90-degree angle on the outer circumference of the upper radial displacement detection ring base (25). The probe of the upper radial displacement sensor (28) is close to the cylindrical surface on the outer side of the upper end of the test rod (6), and the direction of displacement measurement is consistent with the direction of the radial force on the test rod (6).

6. The radial-axial composite magnetic loading device for online testing of mechanical parameters of high-speed electric spindles according to claim 1, characterized in that: The lower radial displacement detection assembly (9) is equipped with four sets of lower radial displacement sensors (31). Two sets of lower radial displacement sensors (31) are arranged at a 90-degree angle on the outer circumference of the lower radial displacement detection ring base (30), ensuring that the direction of displacement measurement is consistent with the direction of the radial force on the test rod (6). The other two sets of lower radial displacement sensors (31) are installed at the angle selected according to the weight. The probe of the lower radial displacement sensor (31) is close to the cylindrical surface on the outer side of the lower end of the test rod (6).

7. The radial-axial composite magnetic loading device for online testing of mechanical parameters of high-speed electric spindles according to claim 1, characterized in that: The displacement sensor of the upper radial displacement detection component (5), the displacement sensor of the lower radial displacement detection component (9), and the axial displacement sensor (12) are electrically connected to the charge amplifier, the charge amplifier is electrically connected to the data acquisition module, the data acquisition module is electrically connected to the mobile workstation (47), and the mobile workstation (47) is also electrically connected to the signal output module (48), the signal output module (48) is electrically connected to the pulse width modulation amplifier (49), the pulse width modulation amplifier (49) is electrically connected to the electromagnet of the middle radial loading part (7) and the electromagnet of the lower axial loading part (11), respectively; and the mobile workstation (47) is also electrically connected to the signal input terminal of the frequency converter through the A / D converter, and the signal output terminal of the frequency converter is electrically connected to the control terminal of the electric spindle (2).

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