A coupling-free method and system for measuring mechanical loss of electric spindle

Abstract

The present invention discloses a non-coupling method and system for measuring the mechanical loss of an electric spindle. The method of the present invention comprises collecting the mechanical angular velocity of the electric spindle at each sampling moment after the electric spindle is suddenly powered off when idling at a target measurement speed until the temperature rise is stable; determining the corresponding electric spindle rotation friction factor according to the mechanical angular velocity at each sampling moment; and calculating the corresponding electric spindle mechanical loss at each sampling moment according to the electric spindle rotation friction factor and the mechanical angular velocity at each sampling moment. The present invention can realize the non-coupling measurement of the mechanical loss of high-speed and ultra-high-speed asynchronous electric spindles. The test object only needs one electric spindle, and the test system does not need a coupling and a power meter. The test system is relatively simple, the measurement cost is low, the measurement process is simple and efficient, the measurement speed range is wide, and the measurement results are reliable.

Description

Technical Field

[0001] The invention relates to electric spindle technology, and in particular to a non-coupling method and system for measuring mechanical loss of an electric spindle. Background Art

[0002] The electric spindle is a new core functional component of machine tools that integrates the functions of the machine tool spindle and the motor in structure. Since the intermediate transmission chain such as belts and gears is omitted in the structure, direct drive is realized. It has outstanding technical advantages such as high speed, high precision, low vibration and noise, small inertia, and fast dynamic response. It can achieve rapid start and stop, accurate stop, accurate positioning, and precise control. It has been more and more widely used in the field of high-speed precision machining. The performance of the electric spindle directly determines the machining accuracy and efficiency of the machine tool. Compared with the permanent magnet synchronous electric spindle, the asynchronous electric spindle has a simple, solid and reliable rotor structure, no demagnetization problem, stable performance, high cost performance, and relatively simple constant power weak magnetic speed control, which is easy to achieve high speed. The application of it in high-speed precision machine tools has reached more than 80%, which has an absolute advantage.

[0003] With the continuous improvement of machining accuracy and machining efficiency, the requirements for the stiffness, precision and speed of electric spindles are getting higher and higher. In order to obtain higher machining efficiency, the high speed and ultra-high speed of electric spindles have become the development direction of electric spindle technology. Mechanical loss is caused by the frictional heat generated by the rotation of the spindle. As the main component of the loss of high-speed and ultra-high-speed electric spindles, it has an important influence on the heating, thermal deformation and machining accuracy of the electric spindle. The existing measurement methods can no longer meet the needs. It is urgent to explore new methods to provide experimental support for the development and design of high-performance high-speed and ultra-high-speed electric spindles, improve the design and propose new design methods.

[0004] The existing method for measuring the mechanical loss of an electric spindle is the coupling method. This method measures the mechanical loss of an electric spindle by coupling two identical electric spindles, any of which can be used as a drive electric spindle or a load electric spindle. The specific implementation process of this method is as follows: ① The load electric spindle is always in a power-off state during the mechanical loss measurement process; ② The coupling is connected to the drive electric spindle (the coupling must always be connected to the drive electric spindle to eliminate the influence of the coupling wind friction loss), but is disconnected from the load electric spindle, and the input active power of the drive electric spindle running at a given speed without load is measured; ③ The coupling is connected to the drive electric spindle and the load electric spindle at the same speed (the same as the no-load measurement speed in step ②) and the input active power of the drive electric spindle running with load is measured; ④ The difference between the measurement results of step ③ and ② is the measured value of the mechanical loss of the electric spindle under the given speed operation condition. By changing the measurement speed and repeating steps ①, ②, ③ and ④, the mechanical loss curve of the electric spindle can be measured.

[0005] The existing coupling method has small measurement error and high accuracy, but it also has obvious shortcomings: ① The test system is relatively complex and the measurement cost is high. The test system not only needs to be equipped with a frequency converter, a test bench, two identical electric spindles, and a coupling, but also needs to be equipped with a speed meter and a power meter. The system is relatively complex, which increases the measurement cost. ② The measurement process is cumbersome and inefficient. The measurement process includes the measurement of the input active power of the driving electric spindle when the coupling is only connected to the driving electric spindle, and the measurement of the input active power of the driving electric spindle when the coupling is connected to the driving electric spindle and the load electric spindle at the same time. In addition, to change the measurement speed, it is necessary to repeatedly remove the load electric spindle from the coupling and repeatedly install the load electric spindle on the coupling. The process is cumbersome, time-consuming and labor-intensive. ③ The measurable speed range is limited. Two identical electric spindles are connected through a coupling to form a new rotor system, which will change the inherent characteristics of the electric spindle itself and cause rotor misalignment. During the speed regulation process, the speed of the electric spindle cannot rise to the maximum operating speed due to resonance or excessive vibration. It is especially not suitable for measuring the mechanical loss of high-speed and ultra-high-speed electric spindles. Summary of the invention

[0006] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, a non-coupling method and system for measuring the mechanical loss of an electric spindle are provided. The present invention can realize the non-coupling measurement of the mechanical loss of high-speed and ultra-high-speed asynchronous electric spindles. The test object only needs one electric spindle, and the test system does not need a coupling and a power meter. The test system is relatively simple and the measurement cost is low. The measurement process is simple and efficient, the measurement speed range is wide, and the measurement results are reliable.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A coupling-free method for measuring mechanical loss of an electric spindle, comprising:

[0009] 1) Collect the mechanical angular velocity of the electric spindle at each sampling time after it is suddenly powered off when it is idling at the target measurement speed until the temperature rise stabilizes;

[0010] 2) Determine the corresponding electric spindle rotation friction factor according to the mechanical angular velocity at each sampling moment;

[0011] 3) According to the rotation friction factor of the electric spindle and the mechanical angular velocity at each sampling moment, the mechanical loss of the electric spindle corresponding to each sampling moment is calculated respectively.

[0012] Optionally, the calculation function expression of the electric spindle rotation friction factor in step 2) is:

[0013]

[0014] In the above formula, cf is the friction factor of the electric spindle, J is the moment of inertia of the electric spindle, ω m2 For any sampling time t m2 The corresponding mechanical angular velocity, ω m1 For any sampling time t m1 The corresponding mechanical angular velocity, T2 is the sampling time t m2 The timing time, T1 is the sampling time t m1 The timing time, n is the highest degree of the polynomial, a j is the jth term of the polynomial t j The coefficient of , t is the time-integrated variable.

[0015] Optionally, the calculation of the electric spindle rotation friction factor in step 2) includes: for different groups of sampling moments t m1 and sampling time t m2 The electric spindle rotation friction factor is calculated, and then the weighted average value of the calculated multiple electric spindle rotation friction factors is taken as the final electric spindle rotation friction factor value.

[0016] Optionally, step 2) further includes the step of determining polynomial coefficients:

[0017] S1) Establish the functional relationship between the speed of the electric spindle and the time after the power is suddenly cut off:

[0018]

[0019] In the above formula, n is the highest degree of the polynomial, a j is the jth term of the polynomial t j The coefficient of m (t) is the mechanical angular velocity corresponding to any time t after the electric spindle is suddenly powered off, and m is the number of intervals of the speed change measurement sampling time after the electric spindle is suddenly powered off;

[0020] S2) The functional relationship between the speed of the electric spindle and time after a sudden power failure is converted into:

[0021]

[0022] S3) curve fitting is performed using the least squares approximation method and the mechanical angular velocity at each sampling moment, and the condition for the minimum value of the curve fitting cumulative error or the sum of squares of the errors is:

[0023]

[0024] In the above formula, is the jth column and kth row element of the coefficient matrix A of the equation system, a j is the jth term of the polynomial t jThe coefficient of k is the kth polynomial coefficient a in the system of equations j The equation constant on the right side of the equation equal sign corresponds to:

[0025]

[0026]

[0027] In the above formula, The i-th sampling time t in the j-th column of the coefficient matrix A of the system of equations i The corresponding function value t i j , The kth row of the coefficient matrix A of the system of equations and the i-th sampling time t i The corresponding function value t i k ,ω i is the i-th sampling time t after the electric spindle suddenly loses power i The corresponding mechanical angular velocity, m is the time interval of the speed change measurement sampling after the electric spindle is suddenly powered off;

[0028] S4) writing the condition for the curve fitting cumulative error or the sum of squares of the errors to obtain the minimum value into a matrix form:

[0029] Aa=d,(7)

[0030] In the above formula, A is the coefficient matrix of the system of equations, a is the column vector composed of the polynomial coefficients of the system of equations, d is the column vector composed of the constants of the system of equations, and:

[0031]

[0032] a=(a0,a1,…,a n ) T , (9)

[0033] d=(d0,d1,…,d n ) T , (10)

[0034] In the above formula, for and The first term is 1 and the common ratio is t i , a geometric sequence with n+1 terms, a0~a n are the unknown numbers to be solved for the polynomial coefficients or the equations, d0~d n The equation constants corresponding to the right side of the equal sign of the 1st to the n+1th equations in the system of equations;

[0035] S5) Substitute the mechanical angular velocity of each sampling time after the electric spindle is suddenly powered off while idling at the target measurement speed until the temperature rise stabilizes into equations (5), (6) and (7), so as to obtain the polynomial coefficients a0~a n The value of .

[0036] Optionally, when calculating the mechanical loss of the electric spindle corresponding to each sampling moment in step 3), any sampling moment t m Corresponding motor spindle mechanical loss P m The calculation formula is:

[0037]

[0038] In the above formula, c f is the friction factor of the electric spindle rotation, ω m For any sampling time t m The corresponding mechanical angular velocity.

[0039] Optionally, in step 1), the electric spindle runs idle at the target speed until the temperature rise stabilizes, which includes: ① starting the auxiliary system of the electric spindle, the auxiliary system including a cooling system and a lubrication system; ② performing a soft start of the electric spindle with reduced voltage and frequency under inverter power supply conditions; ③ increasing the speed of the electric spindle to the target measurement speed by adjusting the power supply frequency of the inverter; ④ the electric spindle runs idle at the target measurement speed until the temperature rise stabilizes to eliminate the influence of temperature on the measurement result.

[0040] Optionally, after calculating the electric spindle mechanical loss corresponding to each sampling moment in step 3), the step further includes generating an electric spindle mechanical loss curve corresponding to the target speed according to the electric spindle mechanical loss corresponding to each sampling moment.

[0041] Optionally, after step 3), it also includes generating a new target speed according to the update, and re-executing steps 1) to 3) for the new target speed to obtain the mechanical loss of the electric spindle corresponding to each sampling time at different target speeds.

[0042] In addition, the present invention also provides a non-coupling system for measuring the mechanical loss of an electric spindle, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the steps of the non-coupling method for measuring the mechanical loss of an electric spindle.

[0043] In addition, the present invention also provides a computer-readable storage medium, in which a computer program is stored. The computer program is used to be executed by a microprocessor to implement the steps of the above-mentioned non-coupling method for measuring the mechanical loss of an electric spindle.

[0044] Compared with the prior art, the present invention mainly has the following advantages:

[0045] 1. The method of the present invention includes collecting the mechanical angular velocity of the electric spindle at each sampling time after the electric spindle is idling at the target measurement speed until the temperature rise is stable and then suddenly powered off; determining the corresponding electric spindle rotation friction factor according to the mechanical angular velocity at each sampling time; and calculating the electric spindle mechanical loss corresponding to each sampling time according to the electric spindle rotation friction factor and the mechanical angular velocity at each sampling time. The test system required by the present invention is relatively simple and has low measurement cost. Compared with the existing coupling method, the non-coupling method of the present invention only requires one electric spindle as the test object, does not require a coupling and a power meter, and the test system is relatively simple, which effectively reduces the measurement cost.

[0046] 2. The measurement process of the present invention is simple and efficient. Compared with the existing coupling method, the non-coupling method of the present invention only needs to measure the speed change of the electric spindle after it is fully idling at a certain speed until the temperature rise is stable and then suddenly powered off. It is not necessary to measure the change in input active power of the driving electric spindle when it is running without load (the measurement speed of the driving electric spindle running without load should be kept the same) before and after the driving electric spindle and the load electric spindle are connected through the coupling. It is not necessary to repeatedly remove the load electric spindle from the coupling and repeatedly install the load electric spindle on the coupling. The measurement process is greatly simplified and the measurement efficiency is high.

[0047] 3. The measurement speed range of the present invention is wide, and can cover the full speed range of the electric spindle. Compared with the existing coupling method, the invented non-coupling method test object only needs one electric spindle, and does not need to connect two completely identical electric spindles through a coupling, which will not change the original dynamic characteristics of the electric spindle. The measurement speed range is wide, and can cover the full speed range of the electric spindle, whether it is low speed, medium speed, high speed, or ultra-high speed. It is particularly suitable for the measurement of mechanical loss of high-speed and ultra-high-speed asynchronous electric spindles. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The figure is a basic flow chart of a method according to a first embodiment of the present invention.

[0049] Figure 2 It is a schematic diagram of the structure of the test system in the first embodiment of the present invention.

[0050] Figure 3 Detailed flowchart of the test method in Embodiment 1 of the present invention.

[0051] Figure 4 Detailed flowchart of the testing method in Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0052] Embodiment 1:

[0053] like Figure 1 As shown, the coupling-free method for measuring the mechanical loss of the electric spindle in this embodiment includes:

[0054] 1) Collect the mechanical angular velocity of the electric spindle at each sampling time after it is suddenly powered off when it is idling at the target measurement speed until the temperature rise stabilizes;

[0055] 2) Determine the corresponding electric spindle rotation friction factor according to the mechanical angular velocity at each sampling moment;

[0056] 3) According to the rotation friction factor of the electric spindle and the mechanical angular velocity at each sampling moment, the mechanical loss of the electric spindle corresponding to each sampling moment is calculated respectively.

[0057] In this embodiment, in step 1), the electric spindle runs idly at the target speed until the temperature rise stabilizes, which includes: ① starting the auxiliary system of the electric spindle, the auxiliary system including a cooling system and a lubrication system, so as to prepare for the start-up, frequency conversion speed regulation and no-load operation of the electric spindle, and mechanical loss separation and measurement; ② performing a voltage and frequency reduction soft start on the electric spindle under the condition of inverter power supply; ③ increasing the speed of the electric spindle to the target measurement speed by adjusting the power supply frequency of the inverter; ④ fully idling the electric spindle at the target measurement speed until the temperature rise stabilizes to eliminate the influence of temperature on the measurement result.

[0058] As a common example of an electric spindle, the electric spindle in this embodiment is specifically a high-speed liquid suspension electric spindle, such as Figure 2 As shown. The test system in this embodiment is mainly composed of an inverter, a tested electric spindle, an infrared speed meter and a stopwatch. The method of this embodiment is an improvement on the existing coupling method. The existing coupling method requires two completely identical electric spindles, any of which can be used as a driving electric spindle or a load electric spindle, which are clutched through a coupling to achieve separation and measurement of mechanical losses. The non-coupling method of this embodiment only requires one electric spindle as the test object during the entire test process. There is no coupling or coupling. The separation and measurement of mechanical losses are achieved by running a single electric spindle at a certain speed without load and combining sudden power failure to eliminate the electric spindle's braking torque and electromagnetic losses. See Figure 2 In step 1), when the electric spindle is running at the target measurement speed and the temperature rise is stable, the power switch S or the power supply of the electric spindle can be suddenly cut off, thereby eliminating the electric spindle braking torque and electromagnetic loss, and completely separating the mechanical loss component from the total loss of the electric spindle. After the electric spindle is suddenly powered off, due to the energy storage effect of inertia, the speed will not drop to zero immediately. Under the combined effect of bearing mechanical friction and rotor wind friction, the speed will show a gradual decline process; see Figure 2 In this embodiment, an infrared speed measuring instrument is used to measure the change in the speed ω of the electric spindle after a sudden power failure, and a stopwatch is used to record the time corresponding to each measured speed. Finally, the mechanical angular velocity at each sampling time is obtained as shown in Table 1.

[0059] Table 1: Original experimental data of mechanical angular velocity at each sampling moment

[0060]

[0061] In Table 1, i+1 is the number of measuring points (i=0, 1, 2, 3, ..., m). In order to accurately reflect the change law of the speed of the electric spindle after a sudden power failure, the number of measuring points i+1 ≥ 5.

[0062] The calculation function expression of the electric spindle rotation friction factor in step 2) of this embodiment is:

[0063]

[0064] In the above formula, c f is the friction factor of the electric spindle, J is the moment of inertia of the electric spindle, ω m2 For any sampling time t m2 The corresponding mechanical angular velocity, ω m1 For any sampling time t m1 The corresponding mechanical angular velocity, T2 is the sampling time t m2 The timing time, T1 is the sampling time t m1 The timing time, n is the highest degree of the polynomial, a j is the jth term of the polynomial t j The coefficient of , t is the time-integrated variable.

[0065] As an optional implementation, in order to reduce the accidental error of measurement, the calculation of the electric spindle rotation friction factor in step 2) of this embodiment includes: for different groups of sampling moments t m1 and sampling time t m2 The electric spindle rotation friction factor is calculated, and then the weighted average value of the calculated multiple electric spindle rotation friction factors is taken as the final electric spindle rotation friction factor value.

[0066] See also Figure 3 In this embodiment, before step 2), the step of determining polynomial coefficients is also included:

[0067] S1) Establish the functional relationship between the speed of the electric spindle and the time after the power is suddenly cut off:

[0068]

[0069] In the above formula, n is the highest degree of the polynomial, a j is the jth term of the polynomial t j The coefficient of m (t) is the mechanical angular velocity corresponding to any time t after the electric spindle is suddenly powered off, and m is the number of intervals of the speed change measurement sampling time after the electric spindle is suddenly powered off;

[0070] S2) The functional relationship between the speed of the electric spindle and time after a sudden power failure is converted into:

[0071]

[0072] S3) curve fitting is performed using the least squares approximation method and the mechanical angular velocity at each sampling moment, and the condition for the minimum value of the curve fitting cumulative error or the sum of squares of the errors is:

[0073]

[0074] In the above formula, is the jth column and kth row element of the coefficient matrix A of the equation system, a j is the jth term of the polynomial t j The coefficient of k is the kth polynomial coefficient a in the system of equations j The equation constant on the right side of the equation equal sign corresponds to:

[0075]

[0076]

[0077] In the above formula, The i-th sampling time t in the j-th column of the coefficient matrix A of the system of equations i The corresponding function value t i j , The kth row of the coefficient matrix A of the system of equations and the i-th sampling time t i The corresponding function value t i k ,ω i is the i-th sampling time t after the electric spindle suddenly loses power i The corresponding mechanical angular velocity, m is the time interval of the speed change measurement sampling after the electric spindle is suddenly powered off;

[0078] S4) writing the condition for the curve fitting cumulative error or the sum of squares of the errors to obtain the minimum value into a matrix form:

[0079] Aa=d,(7)

[0080] In the above formula, A is the coefficient matrix of the system of equations, a is the column vector composed of the polynomial coefficients of the system of equations, d is the column vector composed of the constants of the system of equations, and:

[0081]

[0082] a=(a0,a1,…,a n ) T, (9)

[0083] d=(d0,d1,…,d n ) T , (10)

[0084] In the above formula, for and The first term is 1 and the common ratio is t i , a geometric sequence with n+1 terms, a0~a n are the unknown numbers to be solved for the polynomial coefficients or the equations, d0~d n The equation constants corresponding to the right side of the equal sign of the 1st to the n+1th equations in the system of equations;

[0085] S5) Substitute the mechanical angular velocity of each sampling time after the electric spindle is suddenly powered off while idling at the target measurement speed until the temperature rise stabilizes into equations (5), (6) and (7), so as to obtain the polynomial coefficients a0~a n The value of .

[0086] In this embodiment, when calculating the mechanical loss of the electric spindle corresponding to each sampling time in step 3), any sampling time t m Corresponding motor spindle mechanical loss P m The calculation formula is:

[0087]

[0088] In the above formula, c f is the friction factor of the electric spindle rotation, ω m For any sampling time t m The corresponding mechanical angular velocity.

[0089] See also Figure 3 The process of determining the calculation function expression of the electric spindle rotation friction factor shown in formula (1) in step 2) of this embodiment is as follows: According to the law of conservation of energy, the reduction in its kinetic energy in any time interval after the electric spindle is suddenly powered off is equal to the work done to overcome the friction force including bearing friction and rotor wind resistance in the time interval. The mathematical expression of the energy conservation equation is:

[0090]

[0091] In the above formula, T2 is the sampling time t m2 The timing time (which can be measured by a stopwatch), T1 is the sampling time t m1 The timing time (which can be measured by a stopwatch), P m For any sampling time t m Corresponding mechanical loss of the electric spindle, E k2 and E k1They are respectively the electric spindle at the sampling time t m2 , sampling time t m1 The kinetic energy of the electric spindle, J is the moment of inertia of the electric spindle (a known parameter that can be calculated based on the electric spindle rotor shaft structure, geometric parameters and material density), ω m2 For any sampling time t m2 The corresponding mechanical angular velocity (which can be measured by a tachometer), ω m1 For any sampling time t m1 The corresponding mechanical angular velocity (which can be measured by a tachometer). Substituting equations (2) and (11) into equation (12), the mathematical expression of the electric spindle rotation friction factor is obtained after sorting as shown in equation (1).

[0092] In summary, the non-coupling method for measuring the mechanical loss of the electric spindle in this embodiment mainly has the following advantages: 1. The test system required by this embodiment is relatively simple, and the measurement cost is low. Compared with the existing coupling method, the non-coupling method of the invention only requires one electric spindle as the test object, and does not require a coupling and a power meter. The test system is relatively simple, which effectively reduces the measurement cost. 2. The non-coupling method for measuring mechanical losses by creatively proposing a single electric spindle running at no load and combining sudden power failure to eliminate the braking torque and electromagnetic loss of the electric spindle and realize mechanical loss separation, as well as the non-coupling mechanical loss measurement method in this embodiment have a simple measurement process and high efficiency. Compared with the existing coupling method, the non-coupling method of this embodiment only needs to measure the speed change of the electric spindle after it is fully idling at a certain speed until the temperature rise is stable and then suddenly powered off. It is not necessary to measure the change in the input active power of the driving electric spindle when it is running without load (the measurement speed of the driving electric spindle running without load should be kept the same) before and after the driving electric spindle and the load electric spindle are connected through the coupling. It is not necessary to repeatedly remove the load electric spindle from the coupling and repeatedly install the load electric spindle on the coupling. The measurement process is greatly simplified and the measurement efficiency is high. 3. The measurement speed range of this embodiment is wide, which can cover the full speed regulation range of the electric spindle. Compared with the existing coupling method, the invented non-coupling method test object only needs one electric spindle, and there is no need to connect two completely identical electric spindles through a coupling, which will not change the original dynamic characteristics of the electric spindle. The measurement speed range is wide, which can cover the full speed regulation range of the electric spindle. Whether it is low speed, medium speed, high speed or ultra-high speed, it can be measured, which is particularly suitable for the measurement of mechanical losses of high-speed and ultra-high-speed asynchronous electric spindles. 4. The measurement results of this embodiment are reliable. The law of conservation of energy is used to establish the energy conservation equation after the electric spindle is suddenly powered off. At the same time, the experimental data (the law of change of the speed after the electric spindle is suddenly powered off) is fitted by least squares to ensure the credibility of the measurement results of the mechanical loss of the electric spindle.

[0093] In addition, this embodiment also provides a non-coupling system for measuring the mechanical loss of an electric spindle, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the steps of the non-coupling method for measuring the mechanical loss of an electric spindle.

[0094] In addition, this embodiment further provides a computer-readable storage medium, in which a computer program is stored. The computer program is used to be executed by a microprocessor to implement the steps of the aforementioned non-coupling method for measuring the mechanical loss of an electric spindle.

[0095] Embodiment 2:

[0096] This embodiment is a further improvement on the first embodiment. Figure 4 In step 3) of this embodiment, after calculating the electric spindle mechanical loss corresponding to each sampling moment, it also includes generating an electric spindle mechanical loss curve corresponding to the target speed according to the electric spindle mechanical loss corresponding to each sampling moment.

[0097] In addition, this embodiment also provides a non-coupling system for measuring the mechanical loss of an electric spindle, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the steps of the non-coupling method for measuring the mechanical loss of an electric spindle.

[0098] In addition, this embodiment further provides a computer-readable storage medium, in which a computer program is stored. The computer program is used to be executed by a microprocessor to implement the steps of the aforementioned non-coupling method for measuring the mechanical loss of an electric spindle.

[0099] Embodiment three:

[0100] This embodiment is a further improvement of the embodiment 1. In this embodiment, after step 3), it also includes generating a new target speed according to the update, and re-executing steps 1) to 3) for the new target speed to obtain the mechanical loss of the electric spindle corresponding to each sampling time at different target speeds.

[0101] In addition, this embodiment also provides a non-coupling system for measuring the mechanical loss of an electric spindle, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the steps of the non-coupling method for measuring the mechanical loss of an electric spindle.

[0102] In addition, this embodiment further provides a computer-readable storage medium, in which a computer program is stored. The computer program is used to be executed by a microprocessor to implement the steps of the aforementioned non-coupling method for measuring the mechanical loss of an electric spindle.

[0103] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the functions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0104] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A coupling-free method for measuring the mechanical loss of an electric spindle, characterized in that: include: 1) Collect the mechanical angular velocity of the electric spindle at each sampling time after it is suddenly powered off when it is idling at the target measurement speed until the temperature rise stabilizes; 2) Determine the corresponding electric spindle rotation friction factor according to the mechanical angular velocity at each sampling moment; 3) According to the rotation friction factor of the electric spindle and the mechanical angular velocity at each sampling moment, the mechanical loss of the electric spindle corresponding to each sampling moment is calculated respectively.

2. The coupling-free method for measuring the mechanical loss of an electric spindle according to claim 1, characterized in that: The calculation function expression of the electric spindle rotation friction factor in step 2) is: In the above formula, c f is the friction factor of the electric spindle, J is the moment of inertia of the electric spindle, ω m2 For any sampling time t m2 The corresponding mechanical angular velocity, ω m1 For any sampling time t m1 The corresponding mechanical angular velocity, T2 is the sampling time t m2 The timing time, T1 is the sampling time t m1 The timing time, n is the highest degree of the polynomial, a j is the jth term of the polynomial t j The coefficient of , t is the time-integrated variable.

3. The coupling-free method for measuring the mechanical loss of an electric spindle according to claim 2, characterized in that: The calculation of the electric spindle rotation friction factor in step 2) includes: for different groups of sampling moments t m1 and sampling time t m2 The electric spindle rotation friction factor is calculated, and then the weighted average value of the calculated multiple electric spindle rotation friction factors is taken as the final electric spindle rotation friction factor value.

4. The coupling-free method for measuring the mechanical loss of an electric spindle according to claim 2, characterized in that: Step 2) also includes the step of determining the polynomial coefficients: S1) Establish the functional relationship between the speed of the electric spindle and the time after the power is suddenly cut off: In the above formula, n is the highest degree of the polynomial, a j is the jth term of the polynomial t j The coefficient of m (t) is the mechanical angular velocity corresponding to any time t after the electric spindle is suddenly powered off, and m is the number of intervals of the speed change measurement sampling time after the electric spindle is suddenly powered off; S2) The functional relationship between the speed of the electric spindle and time after a sudden power failure is converted into: S3) curve fitting is performed using the least squares approximation method and the mechanical angular velocity at each sampling moment, and the condition for the minimum value of the curve fitting cumulative error or the sum of squares of the errors is: In the above formula, is the jth column and kth row element of the coefficient matrix A of the equation system, a j is the jth term of the polynomial t j The polynomial coefficients, d k is the kth polynomial coefficient a in the system of equations j The equation constant on the right side of the equation equal sign corresponds to: In the above formula, The i-th sampling time t in the j-th column of the coefficient matrix A of the system of equations i The corresponding function value t i j , The kth row of the coefficient matrix A of the system of equations and the i-th sampling time t i The corresponding function value t i k ,ω i is the i-th sampling time t after the electric spindle suddenly loses power i The corresponding mechanical angular velocity, m is the time interval of the speed change measurement sampling after the electric spindle is suddenly powered off; S4) writing the condition for the curve fitting cumulative error or the sum of squares of the errors to obtain the minimum value into a matrix form: Aa=d,(7) In the above formula, A is the coefficient matrix of the system of equations, a is the column vector composed of the polynomial coefficients of the system of equations, d is the column vector composed of the constants of the system of equations, and: a=(a0,a1,…,a n ) T , (9) d=(d0,d1,…,d n ) T , (10) In the above formula, for and The first term is 1 and the common ratio is t i , a geometric sequence with n+1 terms, a0~a n are the unknown numbers to be solved for the polynomial coefficients or the equations, d0~d n The equation constants corresponding to the right side of the equal sign of the 1st to the n+1th equations in the system of equations; S5) Substitute the mechanical angular velocity of each sampling time after the electric spindle is suddenly powered off while idling at the target measurement speed until the temperature rise stabilizes into equations (5), (6) and (7), so as to obtain the polynomial coefficients a0~a n The value of .

5. The coupling-free method for measuring the mechanical loss of an electric spindle according to claim 1, characterized in that: When calculating the mechanical loss of the electric spindle corresponding to each sampling time in step 3), any sampling time t m Corresponding motor spindle mechanical loss P m The calculation formula is: In the above formula, c f is the friction factor of the electric spindle rotation, ω m For any sampling time t m The corresponding mechanical angular velocity.

6. The coupling-free method for measuring the mechanical loss of an electric spindle according to claim 1, characterized in that: In step 1), the electric spindle runs idle at the target speed until the temperature rise stabilizes, which includes: ① starting the auxiliary system of the electric spindle, the auxiliary system including the cooling system and the lubrication system; ② performing a voltage and frequency reduction soft start on the electric spindle under the condition of inverter power supply; ③ increasing the speed of the electric spindle to the target measurement speed by adjusting the power supply frequency of the inverter; ④ the electric spindle runs idle at the target measurement speed until the temperature rise stabilizes to eliminate the influence of temperature on the measurement result.

7. The non-coupling method for measuring the mechanical loss of an electric spindle according to claim 1, characterized in that: After calculating the electric spindle mechanical loss corresponding to each sampling moment in step 3), the method further includes generating an electric spindle mechanical loss curve corresponding to the target speed according to the electric spindle mechanical loss corresponding to each sampling moment.

8. The non-coupling method for measuring the mechanical loss of an electric spindle according to claim 1, characterized in that: After step 3), it also includes generating a new target speed according to the update, and re-executing steps 1) to 3) for the new target speed to obtain the mechanical loss of the electric spindle corresponding to each sampling time at different target speeds.

9. A coupling-free system for measuring mechanical loss of an electric spindle, comprising a microprocessor and a memory connected to each other, characterized in that: The microprocessor is programmed or configured to execute the steps of the coupling-free method for measuring the mechanical loss of an electric spindle as recited in any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored therein, characterized in that: The computer program is used to be executed by a microprocessor to implement the steps of the non-coupling method for measuring the mechanical loss of an electric spindle as claimed in any one of claims 1 to 8.

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