Method for detecting damping and load mass of a numerically controlled machine tool

Abstract

The embodiment of the application discloses a damping and load quality detection method of a numerical control machine tool, and the damping detection method of the numerical control machine tool comprises the following steps: c According to the stress state of the main shaft motor, a first thrust equation F=F N +M*a+K*v+F is established. c According to the relationship between the machine tool thrust and the main shaft working current, a second thrust equation F=K *I is established. In the state that the machine tool main shaft keeps uniform speed, the current-speed model is established by combining the first thrust equation and the second thrust equation, the speed of the main shaft in the model is changed for multiple tests, and according to the speed and working current measured in each test, the damping of the main shaft is fitted and calculated. The damping and load quality detection method of the numerical control machine tool in the embodiment of the application is simple in steps, convenient to operate, can save a large amount of detection cost and human resources, and can accurately calculate the damping and load quality of the machine tool main shaft.

Description

Technical Field

[0001] This invention belongs to the field of CNC machine tool technology, specifically relating to a method for detecting the damping and load quality of a CNC machine tool. Background Technology

[0002] In modern manufacturing, machine tools are core equipment, and their performance directly affects product quality and production efficiency. Damping and load capacity, as key performance parameters of machine tools, play a crucial role in their machining accuracy, stability, and service life. Therefore, regular testing and evaluation of machine tool damping and load capacity are essential for ensuring normal machine tool operation and improving production efficiency.

[0003] Traditional damping and load mass testing primarily relies on vibration and noise testing. Vibration testing involves installing vibration sensors at different locations on the machine tool to collect vibration data under various operating conditions. The collected data is then processed using data analysis software to assess the machine tool's damping and load mass. However, this method requires significant manual operation, and the accuracy of the test results is limited by the installation location and number of sensors. Furthermore, for some high-precision machine tools, the test results may be affected by factors such as temperature and humidity, making it difficult for traditional vibration testing methods to accurately assess their damping and load mass. Summary of the Invention

[0004] The purpose of this invention is to provide a method for detecting the damping and load mass of CNC machine tools that is simple in steps, easy to operate, can save a lot of detection costs and manpower, and accurately calculate the damping and load mass of the machine tool spindle.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides a damping detection method for a CNC machine tool, comprising:

[0006] Based on the force state of the spindle motor, the first thrust equation is established: F = F c +M*a+K*v+F N Where F is the machine tool thrust, F c Let M be the friction force, a be the load mass, a be the acceleration of the principal axis, K be the damping of the principal axis, v be the velocity of the principal axis, and F be the velocity of the principal axis. N For wave thrust;

[0007] Based on the relationship between machine tool thrust and spindle operating current, a second thrust equation F = K is established. c *I, where F is the machine tool thrust, K c I is the thrust constant, and I is the operating current of the main shaft.

[0008] With the machine tool spindle maintaining a constant speed, a current-velocity model is established by simultaneously applying the first and second thrust equations. The spindle speed v in this model is changed and tested multiple times. Based on the speed and working current measured in each test, the spindle damping K is fitted and calculated.

[0009] In the current-velocity model, F v (I)=K c *I=K*v(I)+C1, where F v (I) represents the thrust of the test machine tool, v(I) represents the test speed in the model, and C1 represents the first constant.

[0010] In one or more embodiments of the present invention, the damping of the spindle is calculated by least squares fitting based on the speed and operating current measured in each test using the current-velocity model.

[0011] In one or more embodiments of the present invention, the thrust constant K c = Rated thrust / Rated current.

[0012] Another specific embodiment of the present invention provides a method for detecting the load quality of a CNC machine tool, comprising:

[0013] Based on the force state of the spindle motor, the first thrust equation is established: F = F c +M*a+K*v+F N Where F is the machine tool thrust, F c Let M be the friction force, a be the load mass, a be the acceleration of the principal axis, K be the damping of the principal axis, v be the velocity of the principal axis, and F be the velocity of the principal axis. N For wave thrust;

[0014] Based on the relationship between machine tool thrust and spindle operating current, a second thrust equation F = K is established. c *I, where F is the machine tool thrust, K c I is the thrust constant, and I is the operating current of the main shaft.

[0015] With the machine tool spindle under uniform acceleration, a current-acceleration model is established by combining the first and second thrust equations. The acceleration in this model is changed and tested multiple times. Based on the acceleration difference and working current difference obtained from each test, the load mass of the spindle is fitted and calculated.

[0016] In the current-acceleration model, ΔF a (I)=K c *△I=M*△a(I)+C2,△F a (I) represents the difference in the thrust of the test machine tool, ΔI represents the difference in the test operating current, Δa(I) represents the difference in the test acceleration, and C2 represents the second constant.

[0017] In one or more embodiments of the present invention, the load mass of the spindle is calculated by least squares fitting based on the acceleration difference and operating current difference obtained from each test and calculation using the current-acceleration model.

[0018] In one or more embodiments of the present invention, the thrust constant K c = Rated thrust / Rated current.

[0019] In one or more embodiments of the present invention, the average speed of the spindle is kept consistent during each test of the control current-acceleration model.

[0020] In one or more embodiments of the present invention, the trajectory of the main axis in the current-acceleration model is the uniform acceleration segment of the seven-segment S-shaped velocity curve trajectory. The seven-segment S-shaped velocity curve trajectory includes an acceleration segment, a uniform acceleration segment, a deceleration segment, a uniform speed segment, an acceleration-deceleration segment, a uniform deceleration segment, and a deceleration-deceleration segment.

[0021] In one or more embodiments of the present invention, the current-acceleration model has a uniform velocity segment in each of the seven S-shaped velocity curve trajectories during each test.

[0022] In one or more embodiments of the present invention, the length L1 of the uniform velocity segment in the seven-segment S-shaped velocity curve trajectory is set to be at least 1 mm, and the maximum acceleration that the uniform acceleration segment can reach is set to A. max The time for acceleration and deceleration is T1, the time for uniform acceleration is T2, and the maximum velocity is v. max =A max *(T1+T2), according to Calculate the minimum acceleration A that can be achieved during the uniform acceleration segment. min Where L is the total length of the seven S-shaped velocity curve trajectories, and the acceleration of the uniform acceleration segment during each test is controlled at a maximum acceleration of A. max and minimum acceleration A min between.

[0023] Compared with the prior art, the damping and load mass detection method for CNC machine tools according to the embodiments of the present invention has simple steps, is easy to operate, can save a lot of detection costs and manpower, and accurately calculate the damping and load mass of the machine tool spindle. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a flowchart of a method for detecting the damping and load quality of a CNC machine tool according to an embodiment of the present invention;

[0026] Figure 2 The force diagram of the spindle motor;

[0027] Figure 3 This is a velocity curve diagram of a current-acceleration model in one embodiment of the present invention;

[0028] Figure 4 This is an acceleration curve of the current-acceleration model in one embodiment of the present invention. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0030] like Figure 1 and Figure 2 The figure shows a damping detection method for a CNC machine tool according to an embodiment of the present invention, which includes steps one to three.

[0031] In step one, as Figure 2 As shown, the first thrust equation F = F is established based on the force state of the spindle motor. c +F 惯 +F 粘 +F N =F c +M*a+K*v+F N Where F is the machine tool thrust, F c Let M be the friction force, a be the load mass, a be the acceleration of the principal axis, K be the damping of the principal axis, v be the velocity of the principal axis, and F be the velocity of the principal axis. N It is a wave thrust.

[0032] In step two, a second thrust equation F = K is established based on the relationship between the machine tool thrust and the spindle operating current. c*I, where K c Let K be the thrust constant. c I is the operating current of the spindle, which can be calculated from the rated current and rated thrust of the machine tool.

[0033] In step three, the first and second thrust equations are solved simultaneously. Since the left-hand sides of both equations are machine tool thrust F, the equation K relating spindle operating current, spindle speed, and spindle acceleration can be obtained. c *I=F c +M*a+K*v+F N .

[0034] To facilitate the calculation of damping K, the influence of acceleration *a* on thrust *F* needs to be eliminated to make solving the above equations easier. Therefore, the test calculation is performed with the machine tool spindle maintaining a constant speed. Since acceleration *a* is zero under constant speed conditions, a current-velocity model is established based on the above simultaneous equations. In the current-velocity model, F... v (I)=K c *I=K*v(I)+C1, where F v (I) represents the thrust of the test machine tool, v(I) represents the test speed in this model, and C1 is the first constant (i.e., C1 = F). C +F N This first constant is independent of damping.

[0035] Based on the current-velocity model described above, the spindle speed in the model can be changed for multiple tests. The damping of the spindle can be calculated by fitting the measured speed and operating current from each test.

[0036] In this process, after measuring the speed and operating current data of the current-velocity model each time, the damping of the spindle can be calculated by fitting using the least squares method.

[0037] In the above equation, the thrust constant K c The thrust constant is calculated from the rated current and rated thrust of the machine tool. The rated current and rated thrust can be obtained by referring to the rated parameters of the machine tool.

[0038] like Figures 1 to 4 The figure shows another embodiment of the load quality detection method for CNC machine tools, which includes steps one to three.

[0039] In step one, as Figure 2 As shown, the first thrust equation F = F is established based on the force state of the spindle motor. c +F 惯 +F 粘 +F N =F c+M*a+K*v+F N Where F is the machine tool thrust, F c Let M be the friction force, a be the load mass, a be the acceleration of the principal axis, K be the damping of the principal axis, v be the velocity of the principal axis, and F be the velocity of the principal axis. N It is a wave thrust.

[0040] In step two, a second thrust equation F = K is established based on the relationship between the machine tool thrust and the spindle operating current. c *I, where K c Let K be the thrust constant. c I is the operating current of the spindle, which can be calculated from the rated current and rated thrust of the machine tool.

[0041] In step three, since the left-hand side of both the first and second thrust equations is the machine tool thrust F, by simultaneously solving the first and second thrust equations, we can obtain the equation K between the spindle operating current, spindle speed, and spindle acceleration. c *I=F c +M*a+K*v+F N .

[0042] To facilitate the calculation of the spindle load mass based on the spindle operating current and acceleration, it is necessary to eliminate the influence of speed. However, since the acceleration is also zero when the speed is zero, the machine tool spindle is in a stationary state, making it impossible to calculate the load mass. Therefore, the difference method is used to eliminate the influence of speed. In this difference method, the average speed of the spindle is controlled to be consistent in each test process, so that the average viscous resistance F in each test process is consistent. Z Since K*v remains consistent, the influence of viscous resistance on machine tool thrust can be eliminated by subtracting the two sets of test results.

[0043] Based on the above difference method, a current-acceleration model ΔF can be established. a (I)=K c *△I=M*△a(I)+C2, where △F a (I) represents the difference in thrust of the test machine tool, ΔI represents the difference in test operating current, Δa(I) represents the difference in test acceleration, and C2 is the second constant (C2 = F). C +F N This second constant is independent of the load mass.

[0044] Based on the above current-acceleration model, the spindle acceleration in the model can be adjusted for multiple tests. Based on the acceleration difference and working current difference obtained from each test, the load mass of the spindle can be fitted and calculated.

[0045] Similarly, after measuring multiple sets of acceleration differences and operating current differences in the current-velocity model, the load mass of the spindle can be calculated using the least squares method. Furthermore, the thrust constant K... c The thrust constant is calculated from the rated current and rated thrust of the machine tool. The rated current and rated thrust can be obtained by referring to the rated parameters of the machine tool.

[0046] In the current-acceleration model, subtracting the two sets of test results can also reduce the influence of irrelevant parameters such as frictional resistance on the machine tool thrust.

[0047] In this process, the trajectory of the principal axis in the current-acceleration model can be referenced from the uniform acceleration segment of the seven-segment S-shaped velocity curve trajectory. The seven-segment S-shaped velocity curve trajectory includes an acceleration segment, a uniform acceleration segment, a deceleration segment, a constant velocity segment, an acceleration / deceleration segment, a uniform deceleration segment, and a deceleration / deceleration segment. Figure 3 and Figure 4 This refers to the velocity and acceleration curves of the acceleration, uniform acceleration, and deceleration segments within the seven-segment S-shaped velocity trajectory.

[0048] To ensure the validity of the seven-segment S-shaped velocity curve trajectory, it is necessary to ensure that the spindle speed of the current-acceleration model reaches its maximum value during each test, so that there is a uniform speed segment after the deceleration segment ends.

[0049] To calculate the key parameters (range of acceleration a) for the uniform velocity segment of the seven S-shaped velocity curve trajectory, the length L1 of the uniform velocity segment in the seven S-shaped velocity curve trajectory is set to be at least 1 mm, and the maximum acceleration that can be achieved in the uniform acceleration segment is set to A. max The time for acceleration and deceleration is T1, the time for uniform acceleration is T2, and the maximum velocity is v. max =A max *(T1+T2), according to Calculate the minimum acceleration A that can be achieved during the uniform acceleration segment. min L is the total length of the seven S-shaped velocity curve trajectories.

[0050] The calculated maximum acceleration value is A. max and minimum value A min During each test, the acceleration of the uniform acceleration phase is controlled at a maximum acceleration of A. max and minimum acceleration A min This is done to ensure that the spindle speed of the current-acceleration model reaches its maximum value during each test.

[0051] In the above embodiments, collecting data on the spindle's operating current, speed, and acceleration is extremely convenient and requires no large number of operators. Therefore, the damping and load mass detection method for CNC machine tools in the embodiments of the present invention is simple in steps, easy to operate, saves a lot of detection costs and human resources, and accurately calculates the damping and load mass of the machine tool spindle.

[0052] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0053] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for detecting the damping of a CNC machine tool, characterized in that, include: Based on the force state of the spindle motor, the first thrust equation is established as F=Fc+M*a+K*v+FN, where F is the machine tool thrust, Fc is the friction force, M is the load mass, a is the acceleration of the spindle, K is the damping of the spindle, v is the velocity of the spindle, and FN is the wave thrust. Based on the relationship between machine tool thrust and spindle operating current, a second thrust equation is established: F = Kc * I, where F is the machine tool thrust, Kc is the thrust constant, and I is the spindle operating current. With the machine tool spindle maintaining a constant speed, a current-velocity model is established by simultaneously applying the first and second thrust equations. The spindle speed v in this model is changed and tested multiple times. Based on the speed and working current measured in each test, the spindle damping K is fitted and calculated. In the current-velocity model, FvI = Kc*I = K*vI + C1, where FvI is the thrust of the test machine tool, vI is the test speed in the model, and C1 is the first constant. Based on the speed and operating current measured in each test using the current-velocity model, the damping of the spindle is calculated by fitting using the least squares method. Thrust constant Kc = rated thrust / rated current.

2. A method for detecting the load quality of a CNC machine tool, characterized in that, include: Based on the force state of the spindle motor, the first thrust equation is established as F=Fc+M*a+K*v+FN, where F is the machine tool thrust, Fc is the friction force, M is the load mass, a is the acceleration of the spindle, K is the damping of the spindle, v is the velocity of the spindle, and FN is the wave thrust. Based on the relationship between machine tool thrust and spindle operating current, a second thrust equation is established: F = Kc * I, where F is the machine tool thrust, Kc is the thrust constant, and I is the spindle operating current. With the machine tool spindle under uniform acceleration, a current-acceleration model is established by combining the first and second thrust equations. The acceleration in this model is changed and tested multiple times. Based on the acceleration difference and working current difference obtained from each test, the load mass of the spindle is fitted and calculated. In the current-acceleration model, △FaI=Kc*△I=M*△aI+C2, where △FaI is the difference in thrust of the test machine tool, △I is the difference in test operating current, △aI is the difference in test acceleration, and C2 is the second constant. Based on the acceleration difference and operating current difference obtained from each test and calculation using the current-acceleration model, the load mass of the spindle is calculated by fitting using the least squares method. Thrust constant Kc = rated thrust / rated current; The average speed of the spindle is kept constant during each test using the control current-acceleration model.

3. The method for detecting the load quality of a CNC machine tool according to claim 2, characterized in that, In the current-acceleration model, the trajectory of the main axis is the uniform acceleration segment of the seven-segment S-shaped velocity curve trajectory. The seven-segment S-shaped velocity curve trajectory includes the acceleration segment, uniform acceleration segment, deceleration segment, uniform speed segment, acceleration-deceleration segment, uniform deceleration segment, and deceleration-deceleration segment.

4. The method for detecting the load quality of a CNC machine tool according to claim 3, characterized in that, In each test, the current-acceleration model showed that all seven S-shaped velocity curve trajectories had a uniform velocity segment.

5. The method for detecting the load quality of a CNC machine tool according to claim 4, characterized in that, The length L1 of the uniform velocity segment in the seven-segment S-shaped velocity curve trajectory is set to be at least 1 mm. The maximum acceleration that can be achieved in the uniform acceleration segment is set to Amax. The time for acceleration and deceleration is T1, and the time for uniform acceleration is T2. The maximum velocity vmax = Amax * (T1 + T2). The minimum acceleration that can be achieved in the uniform acceleration segment is calculated according to L1 = L - v0 * (T1 + (V0Amin)). Where L is the total length of the seven-segment S-shaped velocity curve trajectory. The acceleration of the uniform acceleration segment is controlled between the maximum acceleration Amax and the minimum acceleration Amin during each test.

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