Dynamic response measurement device and evaluation method for motorized spindle under multiple working conditions

Abstract

The invention provides a dynamic response measurement device and evaluation method for an electric spindle under multiple working conditions, and relates to the technical field of electric spindle dynamic performance evaluation. The method comprises the following steps: simulating a plurality of preset working conditions based on the dynamic response measurement device for the motorized spindle under multiple working conditions, and obtaining electromagnetic forces measured by a force sensor and displacements measured by a displacement sensor under the plurality of preset working conditions; based on the electromagnetic force and the displacement, the dynamic stiffness of the motorized spindle under the multiple preset working conditions is determined; based on a Kriging response surface method, modeling the dynamic stiffness of the motorized spindle under a plurality of preset working conditions to obtain the dynamic stiffness of the motorized spindle under all working conditions; and N times of simulation and modeling are repeated, the dynamic stiffness under all the working conditions after N times of modeling is obtained, and the performance margin of the dynamic stiffness of the motorized spindle under the to-be-tested working condition is determined based on the dynamic stiffness under all the working conditions after N times of modeling and the uncertainty theory. According to the invention, quantitative evaluation of the dynamic response of the motorized spindle under different working conditions is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamic performance evaluation of electric spindles, and in particular to a dynamic response measurement device and evaluation method of an electric spindle under multiple working conditions. Background Art

[0002] Machine tools are important basic mechanical equipment and machine tools in the manufacturing industry, and are an indispensable pillar in the development of the national economy. As the core components of CNC machine tools, precision spindle components are in direct contact with the workpiece being processed, so the performance of the spindle directly affects the processing efficiency of the machine tool and the accuracy and reliability of the processed workpiece.

[0003] The dynamic performance of machine tool systems is critical to achieving the required quality and productivity during machining. During machining, the forces generated by material removal apply dynamic excitation to the machine tool spindle, resulting in relative vibrations between the workpiece and the tool tip. These vibrations affect the quality of the workpiece (surface roughness, dimensional accuracy) and productivity (machining instability, catastrophic failure). Therefore, the dynamic performance of the spindle under high-speed rotation must be well characterized, especially the dynamic behavior of the tool tip position. However, due to the nonlinear characteristics of the electric spindle structure and the fact that the bearings inside the electric spindle need to withstand mechanical clearance, local contact stress, lubrication and other factors during machining, the dynamic behavior of the spindle under different working conditions (i.e., workload) can vary greatly. At the same time, due to differences in machining parameters and inconsistencies in tools and materials, the workload during machining is not a definite value, which complicates the measurement of the dynamic response of the spindle tool tip, thus causing trouble for engineers in their decision-making. Summary of the invention

[0004] The embodiment of the present invention provides a device for measuring the dynamic response of an electric spindle under multiple working conditions and an evaluation method, so as to realize the measurement of the dynamic response of the electric spindle under multiple working conditions.

[0005] In the first aspect, an embodiment of the present invention provides a dynamic response measurement device for an electric spindle under multiple working conditions, comprising: an electric spindle, a virtual tool, an electromagnetic excitation module, a force sensor and a displacement sensor; wherein the virtual tool is connected to the electric spindle, and the axis of the electromagnetic excitation module coincides with the axis of the virtual tool; the electromagnetic excitation module is used to provide electromagnetic force for the virtual tool, and the virtual tool is used to simulate different working conditions based on the electromagnetic force provided by the electromagnetic excitation module; the force sensor is connected to the electromagnetic excitation module, and is used to measure the electromagnetic force applied by the electromagnetic excitation module; the displacement sensor is used to measure the displacement of the virtual tool under the action of the electromagnetic force.

[0006] In some embodiments, the virtual tool includes a rotor core, a connecting rod and a pressure block; wherein the connecting rod is used to connect to the electric spindle, the rotor core is the action position of the electromagnetic excitation module, and the pressure block is used to fix the rotor core; the rotor core, the connecting rod and the pressure block are connected by pressing.

[0007] In some embodiments, the rotor core is made of silicon steel sheets.

[0008] In some embodiments, the device also includes a spindle seat, a base plate, a displacement sensor support and an integrated bracket; wherein the electric spindle is fixed on the spindle seat, and the spindle seat is fixed on the base plate; the electromagnetic excitation module and the force sensor are both fixed on the base plate, the displacement sensor support is connected to the integrated bracket and then fixed on the base plate, and the displacement sensor is fixed on the integrated bracket.

[0009] In some embodiments, the displacement sensor is a non-contact eddy current displacement sensor, and the displacement sensor is installed in a split manner.

[0010] In the device for measuring the dynamic response of an electric spindle under multiple working conditions of an embodiment of the present invention, a virtual tool is connected to the electric spindle, and the axis of the electromagnetic excitation module coincides with the axis of the virtual tool; the electromagnetic excitation module is used to provide electromagnetic force for the virtual tool, and the virtual tool is used to simulate different working conditions based on the electromagnetic force provided by the electromagnetic excitation module; the force sensor is connected to the electromagnetic excitation module to measure the electromagnetic force applied by the electromagnetic excitation module; and the displacement sensor is used to measure the displacement of the virtual tool under the action of the electromagnetic force. The present invention can simulate the operation of the electric spindle under different working conditions more realistically based on the electromagnetic excitation module and the virtual tool, and realize the measurement of the dynamic response of the electric spindle under different working conditions through the force sensor and the displacement sensor.

[0011] In a second aspect, an embodiment of the present invention provides a method for evaluating the dynamic response of an electric spindle under multiple working conditions, comprising: simulating multiple preset working conditions based on the dynamic response measurement device for an electric spindle under multiple working conditions described in the first aspect above, and obtaining the electromagnetic force measured by a force sensor and the displacement measured by a displacement sensor under the multiple preset working conditions; determining the dynamic stiffness of the electric spindle under the multiple preset working conditions based on the electromagnetic force and the displacement; modeling the dynamic stiffness of the electric spindle under the multiple preset working conditions based on the Kriging response surface method, and obtaining the dynamic stiffness of the electric spindle under all working conditions; repeating the simulation and modeling N times, obtaining the dynamic stiffness under all working conditions after the N-times modeling, and determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness under all working conditions after the N-times modeling and uncertainty theory.

[0012] In some embodiments, the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested is determined based on the dynamic stiffness and uncertainty theory under all working conditions after the N-times modeling, including: determining a first cumulative distribution function of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness under all working conditions after the N-times modeling; determining multiple related working conditions corresponding to the working condition to be tested based on preset speed uncertainty ranges and force uncertainty ranges; determining a second cumulative distribution function of the dynamic stiffness of the electric spindle under each of the related working conditions based on the dynamic stiffness under all working conditions after the N-times modeling; and determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the first cumulative distribution function and multiple second cumulative distribution functions.

[0013] In some embodiments, determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the first cumulative distribution function and multiple second cumulative distribution functions includes: determining a first target cumulative distribution function with a maximum dynamic stiffness value and a second target cumulative distribution function with a minimum dynamic stiffness value from the first cumulative distribution function and the multiple second cumulative distribution functions; determining the dynamic stiffness margin of the electric spindle under the working condition to be tested based on a dynamic stiffness threshold and the first target cumulative distribution function; determining the uncertainty value of the electric spindle under the working condition to be tested based on the first target cumulative distribution function and the second target cumulative distribution function; determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness margin and the uncertainty value.

[0014] As an example, determining the dynamic stiffness margin of the electric spindle under the working condition to be tested based on the dynamic stiffness threshold and the first target cumulative distribution function includes: determining the first dynamic stiffness corresponding to the first probability value in the first target cumulative distribution function; and determining the difference between the dynamic stiffness threshold and the first dynamic stiffness as the dynamic stiffness margin.

[0015] As an example, the uncertainty value of the electric spindle under the working condition to be tested is determined based on the first target cumulative distribution function and the second target cumulative distribution function, including: determining the second dynamic stiffness corresponding to the first probability value in the second target cumulative distribution function; determining the third dynamic stiffness corresponding to the second probability value in the first target cumulative distribution function; the second probability value is greater than the first probability value; and determining the difference between the third dynamic stiffness and the second dynamic stiffness as the uncertainty value.

[0016] The dynamic response evaluation method of the electric spindle under multiple working conditions of the embodiment of the present invention simulates multiple preset working conditions based on the dynamic response measurement device of the electric spindle under multiple working conditions, obtains the electromagnetic force measured by the force sensor and the displacement measured by the displacement sensor under multiple preset working conditions; based on the electromagnetic force and displacement, the dynamic stiffness of the electric spindle under multiple preset working conditions is determined; based on the Kriging response surface method, the dynamic stiffness of the electric spindle under multiple preset working conditions is modeled to obtain the dynamic stiffness of the electric spindle under all working conditions; repeats the simulation and modeling N times, obtains the dynamic stiffness under all working conditions after N modeling, and based on the dynamic stiffness under all working conditions after N modeling and uncertainty theory, determines the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested. The present invention simultaneously considers the comprehensive influence of cutting force and rotation speed on the dynamic response of the electric spindle, and can more truly reflect the dynamic performance of the machine tool in the actual processing process. And by combining the Kriging response surface method and uncertainty to theoretically calculate the performance margin of dynamic flexibility under different working conditions, the quantitative evaluation of the dynamic response of the electric spindle under different working conditions is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of a device for measuring the dynamic response of an electric spindle under multiple working conditions provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a virtual tool in an embodiment of the present invention; Figure 3 One of the flow charts of the method for evaluating the dynamic response of an electric spindle under multiple working conditions provided by an embodiment of the present invention; Figure 4 A second flow chart of a method for evaluating the dynamic response of an electric spindle under multiple working conditions provided by an embodiment of the present invention; Figure 5 The third flowchart of the method for evaluating the dynamic response of an electric spindle under multiple working conditions provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Machine tools are important basic mechanical equipment and machine tools in the manufacturing industry, and are an indispensable pillar in the development of the national economy. As the core components of high-end CNC machine tools, precision spindle components are in direct contact with the workpiece being processed, so the performance of the spindle directly affects the processing efficiency of the machine tool and the accuracy and reliability of the workpiece being processed. Therefore, how to further improve the dynamic performance of precision spindles has become one of the main bottlenecks restricting the improvement of the core performance indicators of high-end CNC machine tools in my country.

[0021] The dynamic performance of a machine tool system (including spindle, tool, workpiece, and motion table) is critical to achieving the desired quality and productivity during machining. During machining, the forces generated by material removal exert dynamic excitation on the machine tool spindle, resulting in relative vibrations between the workpiece and the tool tip. These vibrations affect the quality of the workpiece (surface roughness, dimensional accuracy) and productivity (machining instability, catastrophic failure). Therefore, the dynamic performance of the spindle under high-speed rotation, especially the dynamic behavior of the tool tip position, must be well characterized and evaluated. However, due to the nonlinear characteristics of the electric spindle structure and the fact that the bearings inside the electric spindle need to withstand mechanical clearance, local contact stress, lubrication and other factors during machining, the dynamic behavior of the spindle under different working conditions (i.e., workload) can vary greatly. At the same time, due to differences in machining parameters and inconsistencies in tools and materials, the workload during machining is not a definite value, but is within a certain range. This uncertainty is called workload uncertainty. The uncertainty in the machining process complicates the evaluation of the dynamic response of the spindle tool tip, which causes confusion for engineers in their decision-making.

[0022] In order to solve the above problems, the present invention provides a dynamic response measurement device and evaluation method of an electric spindle under multiple working conditions.

[0023] Figure 1 The schematic diagram of the structure of the dynamic response measurement device of the electric spindle under multiple working conditions provided by the embodiment of the present invention. Figure 1 As shown, the device includes: an electric spindle 1, a virtual tool 2, an electromagnetic excitation module 3, a force sensor 4 and a displacement sensor 5. Among them, the virtual tool 2 is connected to the electric spindle 1, and the axis of the electromagnetic excitation module 3 coincides with the axis of the virtual tool 2; the electromagnetic excitation module 3 is used to provide electromagnetic force for the virtual tool 2, and the virtual tool 2 is used to simulate different working conditions based on the electromagnetic force provided by the electromagnetic excitation module 3; the force sensor 4 is connected to the electromagnetic excitation module 3, and is used to measure the electromagnetic force applied by the electromagnetic excitation module 3; the displacement sensor 5 is used to measure the displacement of the virtual tool 2 under the action of the electromagnetic force.

[0024] The virtual tool 2 is connected to the electric spindle 1 through a spindle thread interface, and the electromagnetic excitation module 3 is connected to the force sensor 4 through bolts.

[0025] In some embodiments, the electromagnetic force applied by the electromagnetic excitation module includes a static component and a dynamic component. The electromagnetic force control process includes: setting the currents in the two pairs of opposite magnetic poles to and . Bias Current is a constant DC signal, controlling the current The constant DC signal and the sinusoidal dynamic signal with a certain frequency and amplitude are set to accumulate signals to realize the simulation of milling force. The direction of the electromagnetic force can be perpendicular to the axial direction, such as the horizontal direction and vertical direction of the main axis.

[0026] It should be noted that the working conditions in the embodiments of the present invention refer to cutting working conditions, and each working condition corresponds to a specific spindle speed and cutting force. The spindle speed can be directly controlled by the spindle frequency converter, and the cutting force can be simulated by the electromagnetic force applied by the electromagnetic excitation module to the virtual tool to achieve simulation of different working conditions.

[0027] In some embodiments, Figure 1 As shown, the device also includes a spindle seat 6, a base plate 7, a displacement sensor support 8 and an integrated bracket 9. The electric spindle 1 is fixed on the spindle seat 6, and the spindle seat 6 is fixed on the base plate 7; the electromagnetic excitation module 3 and the force sensor 4 are both fixed on the base plate 7, the displacement sensor support 8 is connected to the integrated bracket 9 and then fixed on the base plate 7, and the displacement sensor 5 is fixed on the integrated bracket 9. The displacement sensor support 8 is used to connect with the integrated bracket 9 to fix the integrated bracket 9 on the base plate 7.

[0028] As a possible implementation, the electric spindle 1 is fixed to the spindle seat 6 by bolt connection, the spindle seat 6 is fixed to the base plate 7 by bolt connection, the electromagnetic excitation module 3 and the force sensor 4 are connected together by bolts and then fixed to the base plate 7 by bolt connection. The displacement sensor support 8 and the integrated bracket 9 are connected together by bolts and then fixed to the base plate 7 by bolt connection, and the displacement sensor 5 is fixed to the integrated bracket 9 by bolt connection. There are installation holes for displacement sensors on the top and left and right sides of the integrated bracket 9, which are used for installing displacement sensors in the horizontal and vertical directions of the spindle to realize the displacement measurement of the spindle in the horizontal and vertical directions.

[0029] In some embodiments, the displacement sensor 5 is a non-contact eddy current displacement sensor, and the displacement sensor 5 is installed in a split manner to avoid inaccurate measurements caused by housing vibration when the sensor is installed on the housing of the electromagnetic excitation module.

[0030] In some embodiments, Figure 2As shown, the virtual tool includes a connecting rod 10, a rotor core 11, and a pressure block 12. The connecting rod 10 is used to connect with the electric spindle 1, the rotor core 11 is the action position of the electromagnetic excitation module 3, and the pressure block 12 is used to fix the rotor core 11; the rotor core 11, the connecting rod 10 and the pressure block 12 are connected by press-fitting to form an integral structure. Among them, the rotor core 11 can be made of silicon steel sheets. The rotor core 11, the connecting rod 10 and the pressure block 12 are formed into a stable mechanical connection by press-fitting, so that the virtual tool has efficient mechanical properties and stability during operation.

[0031] In the device for measuring the dynamic response of an electric spindle under multiple working conditions of an embodiment of the present invention, a virtual tool is connected to the electric spindle, and the axis of the electromagnetic excitation module coincides with the axis of the virtual tool; the electromagnetic excitation module is used to provide electromagnetic force for the virtual tool, and the virtual tool is used to simulate different working conditions based on the electromagnetic force provided by the electromagnetic excitation module; the force sensor is connected to the electromagnetic excitation module to measure the electromagnetic force applied by the electromagnetic excitation module; and the displacement sensor is used to measure the displacement of the virtual tool under the action of the electromagnetic force. The present invention can simulate the operation of the electric spindle under different working conditions more realistically based on the electromagnetic excitation module and the virtual tool, and realize the measurement of the dynamic response of the electric spindle under different working conditions through the force sensor and the displacement sensor.

[0032] Figure 3 This is one of the flow charts of the method for evaluating the dynamic response of the electric spindle under multiple working conditions provided by the embodiment of the present invention. It should be noted that the method needs to use the dynamic response measurement device for the electric spindle under multiple working conditions in the above embodiment to simulate different working conditions, and perform evaluation based on the measurement data of the force sensor and the displacement sensor. Figure 3 As shown, the method may include the following steps.

[0033] Step 301 , simulating multiple preset working conditions based on a dynamic response measurement device for an electric spindle under multiple working conditions, and obtaining electromagnetic forces measured by force sensors and displacements measured by displacement sensors under the multiple preset working conditions.

[0034] It should be noted that the preset working conditions in the embodiments of the present invention may be typical cutting working conditions in the art, or may be working conditions set based on actual needs. Each working condition corresponds to a specific electric spindle speed and milling force.

[0035] In some embodiments, the required current signal can be set through the current signal setting module on the equipment according to the dynamic force demand under each preset working condition, and then the converted voltage signal is output to two pulse width modulated amplifiers through the acquisition card. The amplifier converts the output voltage into output current according to a specific amplification factor, and applies it to the electromagnetic excitation module of the dynamic response measurement device of the electric spindle under multiple working conditions, thereby generating radial electromagnetic force. Then the acquisition card stores the displacement and electromagnetic force collected by the displacement sensor and the force sensor in the target storage area.

[0036] Since the signal collected by the displacement sensor contains unnecessary error signals caused by the spindle rotation, the collected signal can be converted into the frequency domain through Fourier transform to identify and determine the unnecessary motion frequency, and then the frequency can be filtered out through Fourier interpolation to obtain the displacement of the electric spindle under the action of electromagnetic force.

[0037] In some embodiments, before performing step 301, a dynamic response measurement device for the electric spindle under multiple working conditions can be installed at a fixed position at the front end of the electric spindle to be tested to ensure the alignment of the electromagnetic excitation module and the electric spindle to be tested. Start the spindle frequency converter to make the electric spindle rotate at a stable speed, and clear and calibrate the displacement sensor and force sensor to prepare for the work. When executing step 301, the different cutting forces applied to the electric spindle during machining are simulated by setting the magnitude of the static force amplitude of the control current, and the magnitude of the electric spindle speed is adjusted to simulate the machining state of the electric spindle under different preset working conditions, and obtain the electromagnetic force measured by the force sensor and the displacement measured by the displacement sensor under each preset working condition.

[0038] Step 302: determining the dynamic stiffness of the electric spindle under a plurality of preset working conditions based on the electromagnetic force and the displacement.

[0039] It can be understood that the electromagnetic force measured by the force sensor under each preset working condition is equivalent to the cutting force exerted on the electric spindle during the cutting process, and the displacement measured by the displacement sensor is equivalent to the radial displacement of the tool tip during the cutting process.

[0040] In some embodiments, each time a preset working condition is simulated, the electromagnetic force and displacement under the working condition can be obtained. For each preset working condition, the ratio of the displacement and the electromagnetic force under the working condition is used as the dynamic stiffness of the electric spindle under the preset working condition.

[0041] Step 303 , based on the Kriging response surface method, the dynamic stiffness of the electric spindle under multiple preset working conditions is modeled to obtain the dynamic stiffness of the electric spindle under all working conditions.

[0042] In some embodiments, the process of modeling the dynamic stiffness of the electric spindle under multiple preset working conditions based on the Kriging response surface method is equivalent to the process of predicting the dynamic stiffness under other working conditions based on the Kriging response surface method according to the dynamic stiffness under multiple preset working conditions, and the prediction process is directly implemented by the Kriging response surface model in the relevant technology. As an example, a dynamic stiffness data set under different working conditions can be obtained based on a large amount of simulation data; the Kriging response surface model is trained based on the data set to continuously adjust the model parameters to obtain a trained Kriging response surface model; the dynamic stiffness of the electric spindle under multiple preset working conditions is input into the trained Kriging response surface model to obtain the dynamic stiffness of the electric spindle under all working conditions.

[0043] Step 304, repeating simulation and modeling N times, obtaining the dynamic stiffness under all working conditions after N times of modeling, and determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness under all working conditions after N times of modeling and uncertainty theory.

[0044] That is to say, steps 301 to 303 are repeated N times, and the dynamic stiffness under all working conditions after N modeling. The dynamic stiffness under all working conditions can be understood as the corresponding relationship between the dynamic stiffness under different loads and speeds, and can be expressed as a surface, and each point in the surface corresponds to a dynamic stiffness under a specific working condition. The dynamic stiffness under all working conditions after N modeling can be N surfaces, each of which is used to express the corresponding relationship between the dynamic stiffness under different cutting forces and speeds.

[0045] Due to the differences in machining parameters and the inconsistency of tools and materials, the workload in the machining process is not a definite value. Within a certain range, this uncertainty is called workload uncertainty. In different machining scenarios, the speed of the electric spindle may also have a certain uncertainty. In order to combine these uncertainties, the dynamic performance of the electric spindle is evaluated, such as Figure 4 As shown, based on the dynamic stiffness and uncertainty theory under all working conditions after N-times modeling, the implementation process of determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested may include the following steps: Step 401 : determining a first cumulative distribution function of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness under all working conditions after N times of modeling.

[0046] The working condition to be tested refers to the working condition to be evaluated, and the number of working conditions to be tested may be one or more. The working condition to be tested corresponds to a specific cutting force (load) and rotation speed.

[0047] In some embodiments, the dynamic stiffness under all working conditions after N times of modeling is equivalent to the corresponding relationship between the dynamic stiffness under N cutting forces and rotation speeds, that is, N data surfaces, so the dynamic stiffness under a working condition to be tested can be determined based on each data surface, so the dynamic stiffness of the electric spindle under the working condition to be tested can have N values, and the first cumulative distribution function can be obtained based on the N dynamic stiffness of the electric spindle under the working condition to be tested.

[0048] The abscissa of the first cumulative distribution function of the dynamic stiffness of the electric spindle under the working condition to be tested is the dynamic stiffness, and the ordinate is the cumulative probability value of the occurrence of the dynamic stiffness.

[0049] Step 402: determining a plurality of related working conditions corresponding to the working condition to be measured based on a preset rotation speed uncertainty range and a preset force uncertainty range.

[0050] The speed uncertainty range and the force uncertainty range can be set based on actual needs. For example, the speed uncertainty range can be set to 5000 rpm, and the force uncertainty range can be set to 500N. The relevant working conditions refer to the working conditions after the uncertainty is introduced into the working conditions to be tested. For example, if the rotational speed under the working conditions to be tested is 10000rpm and the cutting force is 1500N, the relevant working conditions include relevant working condition 1 (rotational speed is 5000rpm, cutting force is 1500N), relevant working condition 2 (rotational speed is 5000rpm, cutting force is 1000N), relevant working condition 3 (rotational speed is 5000rpm, cutting force is 2000N), relevant working condition 4 (rotational speed is 10000rpm, cutting force is 1000N), relevant working condition 5 (rotational speed is 10000rpm, cutting force is 2000N), relevant working condition 6 (rotational speed is 15000rpm, cutting force is 1500N), relevant working condition 7 (rotational speed is 15000rpm, cutting force is 1000N), and relevant working condition 8 (rotational speed is 15000rpm, cutting force is 2000N).

[0051] Step 403 : Based on the dynamic stiffness of all working conditions after N times of modeling, determine a second cumulative distribution function of the dynamic stiffness of the electric spindle under each relevant working condition.

[0052] For each relevant working condition, based on the dynamic stiffness under all working conditions after N times of modeling, the N dynamic stiffnesses of the electric spindle under the relevant working condition can be determined, and based on the N dynamic stiffnesses under the relevant working condition, the second cumulative distribution function of the dynamic stiffness under the relevant working condition can be determined.

[0053] The abscissa of the second cumulative distribution function is the dynamic stiffness under relevant working conditions, and the ordinate is the cumulative probability value of the occurrence of the dynamic stiffness.

[0054] Step 404 : determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the first cumulative distribution function and the plurality of second cumulative distribution functions.

[0055] Among them, the first cumulative distribution function can characterize the random uncertainty caused by measurement errors in different simulation processes, and the second cumulative distribution function can characterize the cognitive uncertainty, so that the performance margin of the obtained dynamic stiffness introduces the uncertainty in the real scene, so that the obtained performance margin more truly reflects the dynamic performance of the electric spindle in the actual machining process.

[0056] In some embodiments, based on the first cumulative distribution function and multiple second cumulative distribution functions, multiple dynamic stiffnesses with a cumulative probability equal to the cumulative probability threshold are determined, and the maximum dynamic stiffness is determined from these multiple dynamic stiffnesses, and the difference between the preset dynamic stiffness threshold and the obtained maximum dynamic stiffness is determined as the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested.

[0057] In some embodiments, Figure 5 As shown, based on the first cumulative distribution function and the plurality of second cumulative distribution functions, the method for determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested may include the following steps.

[0058] Step 501: Determine a first target cumulative distribution function with the maximum dynamic stiffness value and a second target cumulative distribution function with the minimum dynamic stiffness value from a first cumulative distribution function and a plurality of second cumulative distribution functions.

[0059] In some embodiments, the minimum dynamic stiffness and the maximum dynamic stiffness in the dynamic stiffness value range corresponding to the first cumulative distribution function and the multiple second cumulative distribution functions are determined respectively, that is, the minimum dynamic stiffness and the maximum dynamic stiffness corresponding to the first cumulative distribution function, as well as the minimum dynamic stiffness and the maximum dynamic stiffness corresponding to each second cumulative distribution function are obtained, and the cumulative distribution function corresponding to the maximum value of these maximum dynamic stiffnesses is determined as the first target cumulative distribution function, and the cumulative distribution function corresponding to the minimum value of these minimum dynamic stiffnesses is determined as the second target cumulative distribution function.

[0060] Step 502 : determining the dynamic stiffness margin of the electric spindle under the working condition to be tested based on the dynamic stiffness threshold and the first target cumulative distribution function.

[0061] In some embodiments, based on the dynamic stiffness threshold and the first target cumulative distribution function, the implementation process of determining the dynamic stiffness margin of the electric spindle under the working condition to be tested includes: determining the first dynamic stiffness corresponding to the first probability value in the first target cumulative distribution function; and determining the difference between the dynamic stiffness threshold and the first dynamic stiffness as the dynamic stiffness margin. The first probability value may be 0.5, as shown in the following formula (1).

[0062] (1); in, is the dynamic stiffness margin of the electric spindle under the working condition to be tested; is the corresponding electric spindle speed under the working condition to be tested; is the corresponding cutting force under the working condition to be tested; is the first target cumulative distribution function under the working condition to be tested; is the inverse cumulative distribution function corresponding to the first target cumulative distribution function; is the dynamic stiffness threshold.

[0063] Step 503: Determine the uncertainty value of the electric spindle under the working condition to be tested based on the first target cumulative distribution function and the second target cumulative distribution function.

[0064] In some embodiments, based on the first target cumulative distribution function and the second target cumulative distribution function, the implementation process of determining the uncertainty value of the electric spindle under the working condition to be tested may include: determining the second dynamic stiffness corresponding to the first probability value in the second target cumulative distribution function; determining the third dynamic stiffness corresponding to the second probability value in the first target cumulative distribution function; the second probability value is greater than the first probability value; and determining the difference between the third dynamic stiffness and the second dynamic stiffness as the uncertainty value. The first probability value may be 0.5, and the second probability value may be a preset confidence level, such as 0.95, as shown in the following formula (2).

[0065] (2); in, is the uncertainty value of the electric spindle under the working condition to be tested; is the corresponding electric spindle speed under the working condition to be tested; is the corresponding cutting force under the working condition to be tested; is the speed uncertainty range; is the force uncertainty range; is the first target cumulative distribution function under the working condition to be tested; is the second target cumulative distribution function under the working condition to be tested; is the inverse cumulative distribution function corresponding to the first target cumulative distribution function; is the inverse cumulative distribution function corresponding to the second target cumulative distribution function; For confidence.

[0066] Step 504 : determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness margin and the uncertainty value.

[0067] In some embodiments, the ratio of the dynamic stiffness margin to the uncertainty value can be determined as the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested, as shown in the following formula (3).

[0068] (3); in, It is the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested.

[0069] According to the method for evaluating the dynamic response of an electric spindle under multiple working conditions of an embodiment of the present invention, a plurality of preset working conditions are simulated based on the dynamic response measuring device of the electric spindle under multiple working conditions, and the electromagnetic force measured by the force sensor and the displacement measured by the displacement sensor under multiple preset working conditions are measured; based on the electromagnetic force and displacement, the dynamic stiffness of the electric spindle under multiple preset working conditions is determined; based on the Kriging response surface method, the dynamic stiffness of the electric spindle under multiple preset working conditions is modeled to obtain the dynamic stiffness of the electric spindle under all working conditions; the simulation and modeling are repeated N times to obtain the dynamic stiffness under all working conditions after N modeling, and based on the dynamic stiffness under all working conditions after N modeling and uncertainty theory, the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested is determined. The present invention simultaneously considers the comprehensive influence of cutting force and rotation speed on the dynamic response of the electric spindle, and can more truly reflect the dynamic performance of the machine tool in the actual processing process. And by combining the Kriging response surface method and uncertainty to theoretically calculate the performance margin of dynamic flexibility under different working conditions, the quantitative evaluation of the dynamic response of the electric spindle under different working conditions is realized.

[0070] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0071] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for measuring the dynamic response of an electric spindle under multiple working conditions, characterized in that: include: Electric spindle, virtual tool, electromagnetic excitation module, force sensor and displacement sensor; among them, The virtual tool is connected to the electric spindle, and the axis of the electromagnetic excitation module coincides with the axis of the virtual tool; The electromagnetic excitation module is used to provide electromagnetic force for the virtual tool, and the virtual tool is used to simulate different working conditions based on the electromagnetic force provided by the electromagnetic excitation module; The force sensor is connected to the electromagnetic excitation module and is used to measure the electromagnetic force applied by the electromagnetic excitation module; The displacement sensor is used to measure the displacement of the virtual tool under the action of the electromagnetic force.

2. The device according to claim 1, characterized in that The virtual tool includes a rotor core, a connecting rod and a pressing block; wherein, The connecting rod is used to connect with the electric spindle, the rotor core is the action position of the electromagnetic excitation module, and the pressing block is used to fix the rotor core; The rotor core, the connecting rod and the pressing block are connected by press-fitting.

3. The device according to claim 1, characterized in that The rotor core is made of silicon steel sheets.

4. The device according to claim 1, characterized in that The device also includes a spindle seat, a base plate, a displacement sensor support and an integrated bracket; wherein the electric spindle is fixed on the spindle seat, and the spindle seat is fixed on the base plate; the electromagnetic excitation module and the force sensor are both fixed on the base plate, the displacement sensor support is connected to the integrated bracket and then fixed on the base plate, and the displacement sensor is fixed on the integrated bracket.

5. The device according to claim 1, characterized in that The displacement sensor is a non-contact eddy current displacement sensor, and the displacement sensor is installed in a split manner.

6. A method for evaluating the dynamic response of an electric spindle under multiple working conditions, characterized in that: include: Based on the dynamic response measurement device for the electric spindle under multiple working conditions described in any one of claims 1 to 5 above, a plurality of preset working conditions are simulated to obtain the electromagnetic force measured by the force sensor and the displacement measured by the displacement sensor under the plurality of preset working conditions; Based on the electromagnetic force and the displacement, determining the dynamic stiffness of the electric spindle under the plurality of preset working conditions; Based on the Kriging response surface method, the dynamic stiffness of the electric spindle under the plurality of preset working conditions is modeled to obtain the dynamic stiffness of the electric spindle under all working conditions; Repeat the simulation and modeling N times to obtain the dynamic stiffness under all working conditions after the N times of modeling, and determine the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness under all working conditions after the N times of modeling and uncertainty theory.

7. The method according to claim 6, characterized in that The method of determining the performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested based on the dynamic stiffness and uncertainty theory under all working conditions after the N-times modeling comprises: Based on the dynamic stiffness under all working conditions after the N-times modeling, determining a first cumulative distribution function of the dynamic stiffness of the electric spindle under the working condition to be tested; Determining a plurality of related working conditions corresponding to the working condition to be tested based on a preset speed uncertainty range and a force uncertainty range; Determine a second cumulative distribution function of the dynamic stiffness of the electric spindle under each of the relevant working conditions based on the dynamic stiffness under all working conditions after the N-times modeling; Based on the first cumulative distribution function and a plurality of second cumulative distribution functions, a performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested is determined.

8. The method according to claim 7, characterized in that The determining, based on the first cumulative distribution function and a plurality of second cumulative distribution functions, a performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested comprises: Determine, from the first cumulative distribution function and the plurality of second cumulative distribution functions, a first target cumulative distribution function with the maximum dynamic stiffness value and a second target cumulative distribution function with the minimum dynamic stiffness value; Determining the dynamic stiffness margin of the electric spindle under the working condition to be tested based on the dynamic stiffness threshold and the first target cumulative distribution function; Determining an uncertainty value of the electric spindle under the working condition to be tested based on the first target cumulative distribution function and the second target cumulative distribution function; Based on the dynamic stiffness margin and the uncertainty value, a performance margin of the dynamic stiffness of the electric spindle under the working condition to be tested is determined.

9. The method according to claim 8, characterized in that Determining the dynamic stiffness margin of the electric spindle under the working condition to be tested based on the dynamic stiffness threshold and the first target cumulative distribution function includes: Determining a first dynamic stiffness corresponding to a first probability value in the first target cumulative distribution function; The difference between the dynamic stiffness threshold and the first dynamic stiffness is determined as the dynamic stiffness margin.

10. The method according to claim 8, characterized in that The step of determining the uncertainty value of the electric spindle under the working condition to be tested based on the first target cumulative distribution function and the second target cumulative distribution function includes: Determining a second dynamic stiffness corresponding to a first probability value in the second target cumulative distribution function; Determining a third dynamic stiffness corresponding to a second probability value in the first target cumulative distribution function; the second probability value is greater than the first probability value; A difference between the third dynamic stiffness and the second dynamic stiffness is determined as the uncertainty value.

Images