Grinding system and method for controlling grinding system

Abstract

To provide a better control method of a grinding system that grinds a tooth surface of a work-piece in a gear-wheel shape, using a spiral grinding tooth surface of a grinding tool, by engaging the work-piece with the grinding tool to rotate the work-piece.SOLUTION: A grinding system 10 is provided with: a signal obtaining part 90 that obtains a first signal and a second signal; a synchronization signal generating part 92 that generates a synchronization signal for synchronously rotating a first rotating body 106 with respect to a second rotating body 108, on the basis of the first signal and the second signal; a command signal generating part 96 that generates a command signal, on the basis of a predetermined cancelling signal for suppressing variation in rotation speed of the first rotating body due to cogging of a motor that rotates the first rotating body and the synchronization signal; and a signal output part 98 that outputs the command signal generated by the command signal generating part to control the motor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to a grinding system and a method for controlling a grinding system. [Background technology]

[0002] Patent Document 1 discloses a grinding system in which a gear-shaped workpiece and a grinding tool are meshed and rotated to grind the workpiece tooth surface with the spiral grinding tooth surface of the grinding tool. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5467833 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need for better grinding systems and methods of controlling grinding systems.

[0005] The present disclosure aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] A first aspect of the present disclosure is a grinding system that grinds a gear-shaped workpiece with a grinding tool by rotating the workpiece in mesh with the grinding tool and grinding the workpiece tooth surface with the spiral grinding tooth surface of the grinding tool, wherein one of the workpiece and the grinding tool is a first rotating body, and the other of the workpiece and the grinding tool is a second rotating body, and the grinding system includes: a signal acquisition unit that acquires a first signal indicating the rotational speed of the first rotating body and a second signal indicating the rotational speed of the second rotating body; a synchronization signal generation unit that generates a synchronization signal for rotating the first rotating body synchronously with the second rotating body based on the first signal and the second signal; a command signal generation unit that generates a command signal based on the synchronization signal and a predetermined canceling signal for suppressing fluctuations in the rotational speed of the first rotating body due to cogging of a motor that rotates the first rotating body; and a signal output unit that outputs the command signal generated by the command signal generation unit to control the motor.

[0007] A second aspect of the present disclosure is a control method for a grinding system in which a gear-shaped workpiece and a grinding tool are meshed and rotated to grind the workpiece tooth surface of the workpiece with the spiral grinding tooth surface of the grinding tool, wherein one of the workpiece and the grinding tool is a first rotating body, and the other of the workpiece and the grinding tool is a second rotating body, the control method for a grinding system comprising: a signal acquisition step for acquiring a first signal indicating the rotational speed of the first rotating body and a second signal indicating the rotational speed of the second rotating body; a synchronization signal generation step for generating a synchronization signal for rotating the first rotating body synchronously with the second rotating body based on the first signal and the second signal; a command signal generation step for generating a command signal based on the synchronization signal and a predetermined canceling signal for suppressing fluctuations in the rotational speed of the first rotating body due to cogging of a motor that rotates the first rotating body; and a signal output step for outputting the command signal generated in the command signal generation step to control the motor. [Effects of the Invention]

[0008] According to the present disclosure, a better grinding system and a method for controlling the grinding system may be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a grinding system according to an embodiment. [Figure 2] FIG. 2 is a control block diagram of the grinding system. [Figure 3] FIG. 3 is a flowchart showing an example of a method for controlling the grinding system. [Figure 4] FIG. 4 is a flowchart illustrating the canceling signal determination step. [Figure 5] FIG. 5 is a flowchart illustrating the grinding step. DETAILED DESCRIPTION OF THE INVENTION

[0010] In recent years, efforts to realize a low-carbon or carbon-free society have become more active, and research and development of electric vehicles (e.g., hybrid vehicles, fuel cell vehicles) has been conducted to reduce CO2 emissions and improve energy efficiency. Such electric vehicles generate less noise when driven than conventional gasoline-fueled vehicles. Therefore, electric vehicles are required to reduce the noise generated by gear rotation more than gasoline-fueled vehicles. In a grinding system, the rotational speed of a workpiece fluctuates due to the cogging of the motor that rotates the workpiece. Specifically, the rotational speed of the workpiece fluctuates by an amount corresponding to the number of pairs of north and south poles of the motor per rotation of the workpiece. Such fluctuations in the rotational speed of the workpiece may prevent the workpiece tooth flank from being ground accurately. Grinding errors on the workpiece tooth flank caused by the cogging of the motor may cause abnormal noise when the product gear obtained by grinding the workpiece tooth flank is used. The present disclosure may provide a grinding system and a grinding system control method that can reduce grinding errors on the workpiece tooth flank caused by the cogging of the motor.

[0011] Fig. 1 is a perspective view of a grinding system 10 according to an embodiment. As shown in Fig. 1, the grinding system 10 is a system for grinding a gear-shaped workpiece 12 using a grinding tool 14. The grinding system 10 includes a bed 16, a gear support mechanism 18, a gear rotation mechanism 20, a tool support mechanism 22, a tool rotation mechanism 24, and a control device 26.

[0012] The bed 16 is placed on a horizontal surface, for example, in a factory. The gear support mechanism 18 is disposed on the flat upper surface of the bed 16. The gear support mechanism 18 has a cutting table 28, a cutting motor 30, a traverse table 32, and a traverse motor 34.

[0013] The cutting table 28 moves in the direction A relative to the bed 16. The direction A is a horizontal direction perpendicular to the height direction of the bed 16. The cutting table 28 is connected to a cutting motor 30 via a ball screw shaft 36. The cutting motor 30 moves the cutting table 28 in the direction A by rotating the ball screw shaft 36.

[0014] The traverse table 32 is disposed on the upper surface of the cutting table 28. The traverse table 32 moves in the direction B relative to the cutting table 28. The direction B is perpendicular to the height direction of the bed 16 and the direction A. The traverse table 32 is connected to a traverse motor 34 via a ball screw shaft (not shown). The traverse motor 34 moves the traverse table 32 in the direction B by rotating the ball screw shaft.

[0015] The gear rotation mechanism 20 is disposed on the upper surface of the traverse table 32. The gear rotation mechanism 20 has a gear mounting shaft 38 and a first motor 40. The gear mounting shaft 38 extends in the direction B. The workpiece 12 is detachably attached to the gear mounting shaft 38. The first motor 40 rotates the gear mounting shaft 38.

[0016] The tool support mechanism 22 has a column 42, a swivel table 44, a shift table 46, and a shift motor 48. The column 42 is disposed on the upper surface of the bed 16 so as to face the gear support mechanism 18. The column 42 extends upward from the bed 16. The swivel table 44 is attached to the surface of the column 42 facing the gear support mechanism 18.

[0017] The swivel table 44 extends in one direction. A swivel motor (not shown) swivels the swivel table 44 in direction C relative to the column 42. A shift table 46 is provided on the surface of the swivel table 44 facing the gear support mechanism 18. The shift table 46 is connected to a shift motor 48 via a ball screw shaft 50. The shift motor 48 is attached to the swivel table 44. The shift motor 48 moves the shift table 46 in direction D relative to the swivel table 44.

[0018] The tool rotation mechanism 24 has a base portion 54, a tool mounting shaft 56, and a second motor 58. The base portion 54 is attached to the surface of the shift table 46 that faces the gear support mechanism 18. The base portion 54 extends in the extension direction of the swivel table 44. The tool mounting shaft 56 is inserted through the base portion 54 in the extension direction of the base portion 54. The grinding tool 14 is detachably attached to the tool mounting shaft 56. The second motor 58 rotates the tool mounting shaft 56.

[0019] As shown in Figure 2, the workpiece 12 is attached to the gear mounting shaft 38. The workpiece 12 can be rotated in the R1 direction and the R2 direction by the driving force of the first motor 40. The workpiece 12 has a plurality of teeth 60. Each of the plurality of teeth 60 is formed with a workpiece tooth surface 62. The workpiece tooth surface 62 includes a left workpiece tooth surface 62a and a right workpiece tooth surface 62b.

[0020] The grinding tool 14 is attached to the tool mounting shaft 56. The grinding tool 14 can rotate in the R3 direction and the R4 direction by the driving force of the second motor 58. The grinding tool 14 is a tool for grinding the workpiece 12. The grinding tool 14 has a spiral grinding tooth 64. The grinding tooth 64 is formed with a grinding tooth surface 66. The grinding tooth surface 66 includes a first grinding tooth surface 66a and a second grinding tooth surface 66b. For example, a single layer of CBN (cubic boron nitride) abrasive grains or the like is electrodeposited on the grinding tooth surface 66 via a nickel plating layer.

[0021] When grinding the workpiece 12 with the grinding tool 14, the workpiece 12 and the grinding tool 14 are engaged. With the workpiece 12 and the grinding tool 14 engaged, the left workpiece tooth flank 62a faces the first grinding tooth flank 66a, and the right workpiece tooth flank 62b faces the second grinding tooth flank 66b. With the workpiece 12 and the grinding tool 14 engaged, for example, by rotating the workpiece 12 in the R1 direction and rotating the grinding tool 14 in the R3 direction, the left workpiece tooth flank 62a can be ground by the first grinding tooth flank 66a, and the right workpiece tooth flank 62b can be ground by the second grinding tooth flank 66b. In addition, with the workpiece 12 and the grinding tool 14 engaged, for example, by rotating the workpiece 12 in the R2 direction and rotating the grinding tool 14 in the R4 direction, the left workpiece tooth surface 62a can be ground by the first grinding tooth surface 66a and the right workpiece tooth surface 62b can be ground by the second grinding tooth surface 66b.

[0022] The grinding system 10 further includes a first encoder 68 and a second encoder 70. The first encoder 68 is provided on the first motor 40. The first encoder 68 outputs information (e.g., a pulse signal) relating to the rotational phase (rotational speed, rotation angle, rotational position, and rotation amount) of the workpiece 12 to the control device 26.

[0023] The second encoder 70 is provided on the second motor 58. The second encoder 70 outputs information (for example, a pulse signal) relating to the rotational phase (rotational speed, rotational angle, rotational position, and rotation amount) of the grinding tool 14 to the control device 26.

[0024] The control device 26 includes a first servo amplifier 74, a second servo amplifier 76, and a control main body 78. The first servo amplifier 74 controls the rotation of the first motor 40 based on a command signal output from the control main body 78. The second servo amplifier 76 controls the rotation of the second motor 58 based on a command signal output from the control main body 78.

[0025] The control main body 78 includes a calculation unit 80, a storage unit 82, an operation unit 84, and a display unit 86. The calculation unit 80 is configured by a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the calculation unit 80 is configured by processing circuitry.

[0026] The calculation unit 80 includes a control unit 88, a signal acquisition unit 90, a synchronization signal generation unit 92, a canceling signal determination unit 94, a command signal generation unit 96, a signal output unit 98, a determination unit 100, a phase search unit 102, and an amplitude search unit 104. The control unit 88 controls the cutting motor 30, the traverse motor 34, a swing motor (not shown), and the shift motor 48. The signal acquisition unit 90 acquires a first signal indicating the rotational speed of the workpiece 12 and a second signal indicating the rotational speed of the grinding tool 14. The signal acquisition unit 90 acquires the first signal based on information output from the first encoder 68. The signal acquisition unit 90 acquires the second signal based on information output from the second encoder 70.

[0027] The synchronization signal generation unit 92 generates a synchronization signal (workpiece axis speed command signal) for rotating the workpiece 12 synchronously with the grinding tool 14 based on the first signal and the second signal. The synchronization signal is a voltage signal corresponding to the rotational speed of the workpiece 12. The synchronization signal may be a digital signal. The canceling signal determination unit 94 determines a canceling signal for suppressing fluctuations in the rotational speed of the workpiece 12 due to cogging of the first motor 40. The command signal generation unit 96 generates a command signal based on the canceling signal and the synchronization signal. The signal output unit 98 outputs the command signal generated by the command signal generation unit 96 to the first servo amplifier 74 to control the rotation of the first motor 40. The command signal is an analog signal. If the first servo amplifier 74 supports digital signals, the command signal may be a digital signal. The determination unit 100 performs a determination process, which will be described later. The phase search unit 102 searches for an optimal phase of a candidate signal that serves as a candidate for the canceling signal. The amplitude search unit 104 searches for the optimum amplitude of the candidate signal.

[0028] The control unit 88, the signal acquiring unit 90, the synchronization signal generating unit 92, the canceling signal determining unit 94, the command signal generating unit 96, the signal output unit 98, the determining unit 100, the phase searching unit 102, and the amplitude searching unit 104 can be realized by the calculation unit 80 executing a program stored in the storage unit 82. Note that at least a portion of the control unit 88, the signal acquiring unit 90, the synchronization signal generating unit 92, the canceling signal determining unit 94, the command signal generating unit 96, the signal output unit 98, the determining unit 100, the phase searching unit 102, and the amplitude searching unit 104 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). In addition, at least a portion of the control unit 88, signal acquisition unit 90, synchronization signal generation unit 92, canceling signal determination unit 94, command signal generation unit 96, signal output unit 98, judgment unit 100, phase search unit 102, and amplitude search unit 104 may be configured by electronic circuits including discrete devices.

[0029] The storage unit 82 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). An example of the volatile memory is a random access memory (RAM). The volatile memory is used as a working memory for the processor, and temporarily stores data necessary for processing or calculation. An example of the non-volatile memory is a read-only memory (ROM) or a flash memory. The non-volatile memory is used as a storage memory, and stores programs, tables, maps, etc. At least a part of the storage unit 82 may be provided in the processor, integrated circuit, etc. described above.

[0030] The operation unit 84 is used when the user operates the control device 26. The operation unit 84 may include a keyboard, a mouse, etc. The display unit 86 is provided with a display element (not shown). For example, a liquid crystal display element, an organic electroluminescence display element, etc. may be used as the display element. The operation unit 84 and the display unit 86 may be configured by a touch panel (not shown) provided with such a display element.

[0031] Next, an example of a control method for the grinding system 10 will be described. Fig. 3 is a flowchart showing an example of a control method for the grinding system 10. Fig. 4 is a flowchart explaining a canceling signal determination step. Fig. 5 is a flowchart explaining a grinding step. In this embodiment, an example in which a plurality of workpieces 12 are ground will be described.

[0032] 3, a canceling signal determination step is performed in step S1. In the canceling signal determination step, the workpiece 12 is attached to the gear mounting shaft 38, and the grinding tool 14 is attached to the tool mounting shaft 56. Thereafter, in the canceling signal determination step, while the workpiece 12 (first rotating body 106) and the grinding tool 14 (second rotating body 108) are rotating without being meshed with each other, the phase and amplitude of a candidate signal that is a canceling signal are adjusted, and the candidate signal that minimizes the amount of fluctuation in the rotational speed of the workpiece 12 caused by cogging of the first motor 40 (motor that rotates the first rotating body 106) is determined as the canceling signal.

[0033] That is, in the canceling signal determination step, a phase search step is performed in step S10 as shown in FIG. 4. In the phase search step, the phase search unit 102 searches for the optimal phase of the candidate signal that minimizes the amount of fluctuation in the rotational speed of the workpiece 12 by rotating the workpiece 12 while changing the phase of the candidate signal while keeping the amplitude of the candidate signal constant. The candidate signal is a sine wave having a frequency corresponding to the frequency of the fluctuation in the rotational speed of the workpiece 12 caused by cogging. In other words, the frequency of the candidate signal is the same as the frequency of the fluctuation in the rotational speed of the workpiece 12 caused by cogging.

[0034] Specifically, in the phase search step, while the workpiece 12 and the grinding tool 14 are rotating without being meshed with each other, the synchronization signal generation unit 92 generates a synchronization signal for rotating the workpiece 12 synchronously with the grinding tool 14 based on the first signal and the second signal. The canceling signal determination unit 94 generates a candidate signal. The command signal generation unit 96 generates a command signal based on the synchronization signal generated by the synchronization signal generation unit 92 and the candidate signal generated by the canceling signal determination unit 94. The signal output unit 98 outputs the command signal generated by the command signal generation unit 96 to the first servo amplifier 74. The signal acquisition unit 90 acquires a first signal indicating the rotational speed of the workpiece 12 and a second signal indicating the rotational speed of the grinding tool 14.

[0035] In the phase search step, the amplitude of the candidate signal is maintained constant until the phase search step is completed. In the phase search step, the phase of the candidate signal is updated (changed) each time the workpiece 12 rotates through the candidate signal maintenance angle. In other words, in the phase search step, the workpiece 12 is rotated through a predetermined candidate signal maintenance angle while maintaining the phase of the candidate signal constant. The candidate signal maintenance angle is determined based on the period at which cogging of the first motor 40 occurs. In other words, the candidate signal maintenance angle is determined to be a rotation angle of the workpiece 12 at which cogging of the first motor 40 may occur. The canceling signal determination unit 94 performs frequency analysis (Fourier transform) on data of the rotation speed of the workpiece 12 in a range corresponding to the candidate signal maintenance angle, and obtains an amplitude component with the same frequency as the cogging frequency of the first motor 40. This amplitude component indicates fluctuations in the rotation speed of the workpiece 12 due to cogging of the first motor 40. In the phase search step, the phase of the candidate signal at which fluctuations in the rotation speed of the workpiece 12 due to cogging of the first motor 40 are minimized is determined as the optimal phase. After this, the process proceeds to step S11.

[0036] In step S11, an amplitude search step is performed. In the amplitude search step, the amplitude search unit 104 searches for the optimal amplitude of the candidate signal that minimizes the amount of fluctuation in the rotation speed of the first motor 40 by rotating the workpiece 12 while changing the amplitude of the candidate signal while maintaining the phase of the candidate signal at the optimal signal.

[0037] Specifically, in the amplitude search step, while the workpiece 12 and the grinding tool 14 are rotating without being meshed with each other, the synchronization signal generation unit 92 generates a synchronization signal for rotating the workpiece 12 synchronously with the grinding tool 14 based on the first signal and the second signal. The canceling signal determination unit 94 generates a candidate signal. The command signal generation unit 96 generates a command signal based on the synchronization signal generated by the synchronization signal generation unit 92 and the candidate signal generated by the canceling signal determination unit 94. The signal output unit 98 outputs the command signal generated by the command signal generation unit 96 to the first servo amplifier 74. The signal acquisition unit 90 acquires a first signal indicating the rotational speed of the workpiece 12 and a second signal indicating the rotational speed of the grinding tool 14.

[0038] In the amplitude search step, the phase of the candidate signal is maintained at the optimal phase found in the phase search step until the amplitude search step is completed. In the amplitude search step, the amplitude of the candidate signal is updated (changed) each time the workpiece 12 rotates through the candidate signal maintaining angle. In other words, in the amplitude search step, the workpiece 12 is rotated through the candidate signal maintaining angle while maintaining the amplitude of the candidate signal constant. The canceling signal determination unit 94 performs frequency analysis (Fourier transform) on data of the rotational speed of the workpiece 12 in a range corresponding to the candidate signal maintaining angle, and obtains an amplitude component with the same frequency as the cogging frequency of the first motor 40. In the amplitude search step, the amplitude of the candidate signal that minimizes fluctuations in the rotational speed of the workpiece 12 due to cogging of the first motor 40 is determined as the optimal amplitude. The canceling signal determination unit 94 determines the candidate signal having the optimal phase and optimal amplitude as the canceling signal. After this, the process proceeds to step S2.

[0039] As shown in Fig. 3, a grinding step is performed in step S2. In the grinding step, the workpiece 12 and the grinding tool 14 are meshed with each other and rotated, so that the workpiece tooth surface 62 of the workpiece 12 is ground by the grinding tooth surface 66 of the grinding tool 14. In this case, as shown in Fig. 5, in step S20, the workpiece 12 and the grinding tool 14 are meshed with each other. In step S20, a signal acquisition step is performed. In the signal acquisition step, the signal acquisition unit 90 acquires a first signal indicating the rotation speed of the workpiece 12 and a second signal indicating the rotation speed of the grinding tool 14. After this, the process proceeds to step S21.

[0040] In step S21, a synchronization signal generation step is performed. In the synchronization signal generation step, the synchronization signal generation unit 92 generates a synchronization signal for synchronously rotating the workpiece 12 with respect to the grinding tool 14 based on the first signal and the second signal. In other words, the synchronization signal generation unit 92 obtains the phase difference (pulse difference) between the first signal output from the first encoder 68 and the second signal output from the second encoder 70, and generates a synchronization signal that reduces the phase difference. After this, the process proceeds to step S22.

[0041] In step S22, a command signal generation step is performed. In the command signal generation step, the command signal generation unit 96 generates a command signal based on a predetermined canceling signal for suppressing fluctuations in the rotational speed of the workpiece 12 due to cogging of the first motor 40 that rotates the workpiece 12, and a synchronization signal. In other words, the command signal generation unit 96 generates a command signal based on the canceling signal determined in the canceling signal determination step and the synchronization signal generated in the synchronization signal generation step. After this, the process proceeds to step S23.

[0042] In step S23, a signal output step is performed. In the signal output step, the signal output unit 98 outputs the command signal generated by the command signal generation unit 96 to control the first motor 40. In other words, the signal output unit 98 outputs the command signal to the first servo amplifier 74. The first servo amplifier 74 controls the rotation speed of the first motor 40 based on the command signal output from the signal output unit 98. In this case, since the command signal is generated based on the synchronization signal and the canceling signal, it is possible to suppress fluctuations in the rotation speed caused by cogging of the first motor 40 when the workpiece 12 rotates.

[0043] This allows the workpiece tooth surface 62 of the workpiece 12 to be ground with high precision by the grinding tooth surface 66 of the grinding tool 14. In this embodiment, the workpiece tooth surface 62 is ground over the entire circumference of the workpiece 12. After the grinding step is completed, the product gear obtained by grinding the workpiece 12 is removed from the gear mounting shaft 38. Then, the process proceeds to step S3.

[0044] In step S3, the determination unit 100 determines whether grinding has been completed for all of the workpieces 12. If the determination unit 100 determines that grinding has not been completed for all of the workpieces 12 (NO in step S3), the determination unit 100 determines whether the grinding conditions have been changed. Here, the grinding conditions refer to the size of the workpiece 12, the shape of the workpiece 12, the rotational speed of the workpiece 12 in the grinding step, the size of the grinding tool 14, the shape of the grinding tool 14, the rotational speed of the grinding tool 14 in the grinding step, etc.

[0045] If the determination unit 100 determines that the grinding conditions have not been changed (NO in step S4), the workpiece 12 is mounted on the gear mounting shaft 38, and then the process proceeds to step S2. That is, in this case, the canceling signal determination step is not performed. This is because, if the grinding conditions have not been changed, the workpiece 12 can be ground with high precision using the canceling signal that has already been determined.

[0046] If the determination unit 100 determines that the grinding conditions have been changed (YES in step S4), for example, a workpiece having a different shape from the workpiece 12 ground previously is attached to the gear mounting shaft 38. In some cases, the grinding tool 14 may be replaced. After this, the process proceeds to step S1. That is, in this case, a canceling signal determination step is performed to determine a new canceling signal corresponding to the current grinding conditions.

[0047] If the determining unit 100 determines that grinding of all the workpieces 12 has been completed (YES in step S3), the process shown in FIG. 3 ends.

[0048] According to this embodiment, the first motor 40 is controlled by a command signal generated based on the canceling signal and the synchronization signal. Therefore, it is possible to suppress fluctuations in the rotation speed of the workpiece 12 caused by cogging of the first motor 40 when grinding the workpiece tooth surface 62. This reduces grinding errors in the workpiece tooth surface 62, thereby suppressing the generation of abnormal noise when using the product gear obtained by grinding the workpiece tooth surface 62. Therefore, it is possible to provide a better grinding system 10 and a control method for the grinding system 10.

[0049] In the above-described embodiment, an example has been described in which the workpiece 12 is the first rotating body 106 and the grinding tool 14 is the second rotating body 108. The present disclosure is not limited to such an example, and for example, the grinding tool 14 may be the first rotating body 106 and the workpiece 12 may be the second rotating body 108. In this case, in the canceling signal determination step, the canceling signal determination unit 94 adjusts the phase and amplitude of candidate signals that are candidates for the canceling signal while the grinding tool 14 and the workpiece 12 are rotating without meshing with each other, and determines, as the canceling signal, a candidate signal that minimizes the amount of fluctuation in the rotational speed of the grinding tool 14 due to cogging. Furthermore, in the synchronization signal generation step, the synchronization signal generation unit 92 generates a synchronization signal for synchronously rotating the grinding tool 14 with respect to the workpiece 12 based on the first signal and the second signal. Furthermore, in a command signal generating step, the command signal generating unit 96 generates a command signal based on a predetermined canceling signal and a synchronization signal for suppressing fluctuations in the rotational speed of the grinding tool 14 caused by cogging of the second motor 58 that rotates the grinding tool 14. Furthermore, in a signal output step, the signal output unit 98 outputs the command signal generated by the command signal generating unit 96 to control the second motor 58.

[0050] The following additional notes are further disclosed regarding the above embodiment.

[0051] (Appendix 1) The grinding system (10) of the present disclosure is a grinding system that rotates a gear-shaped workpiece (12) and a grinding tool (14) in mesh with each other to grind a workpiece tooth surface (62) of the workpiece with a spiral grinding tooth surface (66) of the grinding tool, wherein one of the workpiece and the grinding tool is a first rotating body (106), and the other of the workpiece and the grinding tool is a second rotating body (108), and includes a signal acquisition unit (90) that acquires a first signal indicating the rotational speed of the first rotating body and a second signal indicating the rotational speed of the second rotating body; The motor control system includes a synchronization signal generating unit (92) that generates a synchronization signal for rotating the first rotating body synchronously with the second rotating body based on the first signal and the second signal, a command signal generating unit (96) that generates a command signal based on a predetermined canceling signal for suppressing fluctuations in the rotational speed of the first rotating body due to cogging of a motor (40, 58) that rotates the first rotating body, and the synchronization signal, and a signal output unit (98) that outputs the command signal generated by the command signal generating unit to control the motor.

[0052] With this configuration, the motor that rotates the first rotating body is controlled by a command signal generated based on the canceling signal and the synchronization signal. This reduces fluctuations in the rotational speed of the first rotating body due to cogging of the motor when grinding the workpiece tooth surface. This reduces grinding errors on the workpiece tooth surface, thereby suppressing the generation of abnormal noise when using the product gear obtained by grinding the workpiece tooth surface. This provides a better grinding system.

[0053] (Appendix 2) The grinding system described in Appendix 1 may further include a canceling signal determination unit (94) that adjusts the amplitude and phase of a candidate signal that is a candidate for the canceling signal while the first rotating body and the second rotating body are rotating without meshing with each other, and determines, as the canceling signal, the candidate signal that minimizes the amount of fluctuation in the rotational speed of the first rotating body caused by the cogging.

[0054] With this configuration, the canceling signal can be determined easily.

[0055] (Appendix 3) In the grinding system according to Supplementary Note 2, the candidate signal may be a sine wave having a frequency corresponding to a frequency of fluctuations in the rotational speed of the first rotating body caused by the cogging.

[0056] With this configuration, fluctuations in the rotation speed of the first rotor caused by cogging can be further reduced.

[0057] (Appendix 4) In the grinding system described in Supplementary Note 2 or 3, the canceling signal determination unit may include a phase search unit (102) that searches for an optimal phase of the candidate signal that minimizes the amount of variation by rotating the first rotating body while changing the phase of the candidate signal while keeping the amplitude of the candidate signal constant, and an amplitude search unit (104) that searches for an optimal amplitude of the candidate signal that minimizes the amount of variation by rotating the first rotating body while changing the amplitude of the candidate signal while keeping the phase of the candidate signal at the optimal phase.

[0058] With this configuration, it is possible to efficiently find a candidate signal that minimizes the amount of fluctuation in the rotation speed of the first rotating body caused by cogging.

[0059] (Appendix 5) In the grinding system according to any one of Supplementary Notes 1 to 4, the first rotating body may be the workpiece, and the second rotating body may be the grinding tool.

[0060] With this configuration, fluctuations in the rotation speed of the workpiece caused by cogging of the motor that rotates the workpiece can be suppressed.

[0061] (Appendix 6) The grinding system control method disclosed herein is a grinding system control method that grinds a gear-shaped workpiece by rotating the workpiece in mesh with a grinding tool and grinding the workpiece tooth surface with the spiral grinding tooth surface of the grinding tool, wherein one of the workpiece and the grinding tool is a first rotating body, and the other of the workpiece and the grinding tool is a second rotating body, and the method includes a signal acquisition step of acquiring a first signal indicating the rotational speed of the first rotating body and a second signal indicating the rotational speed of the second rotating body, a synchronization signal generation step of generating a synchronization signal for rotating the first rotating body synchronously with the second rotating body based on the first signal and the second signal, a command signal generation step of generating a command signal based on the synchronization signal and a predetermined canceling signal for suppressing fluctuations in the rotational speed of the first rotating body due to cogging of the motor that rotates the first rotating body, and a signal output step of outputting the command signal generated in the command signal generation step to control the motor.

[0062] According to this method, the same effect as that of Supplementary Note 1 can be achieved, and therefore a better method for controlling the grinding system can be provided.

[0063] (Appendix 7) The grinding system control method described in Appendix 6 may further include a canceling signal determination step of adjusting the amplitude and phase of a candidate signal that is a candidate for the canceling signal while the first rotating body and the second rotating body are rotating without meshing with each other, and determining, as the canceling signal, the candidate signal that minimizes the amount of fluctuation in the rotational speed of the first rotating body caused by the cogging.

[0064] According to this method, the same effect as that of Supplementary Note 2 can be achieved.

[0065] (Appendix 8) In the grinding system control method described in Supplementary Note 7, the candidate signal may be a sine wave having a frequency corresponding to a frequency of fluctuations in the rotational speed of the first rotating body caused by the cogging.

[0066] According to this configuration, the same effect as that of Supplementary Note 3 can be achieved.

[0067] (Appendix 9) In the method for controlling a grinding system according to Supplementary Note 7 or 8, the canceling signal determination step may include a phase search step of searching for an optimal phase of the candidate signal at which the amount of variation is minimized by rotating the first rotating body while changing the phase of the candidate signal while keeping the amplitude of the candidate signal constant, and an amplitude search step of searching for an optimal amplitude of the candidate signal at which the amount of variation is minimized by rotating the first rotating body while changing the amplitude of the candidate signal while keeping the phase of the candidate signal at the optimal phase.

[0068] According to this method, the same effect as that of Supplementary Note 4 can be achieved.

[0069] (Appendix 10) In the method for controlling a grinding system according to any one of Supplementary Notes 6 to 9, the first rotating body may be the workpiece, and the second rotating body may be the grinding tool.

[0070] According to this method, the same effect as that of Supplementary Note 5 can be achieved.

[0071] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0072] 10...Grinding system 12...Workpiece 14... Grinding tool 40... First motor 58... Second motor 62... Work tooth surface 66...Grounded tooth surface 90...Signal acquisition unit 92... Synchronization signal generating unit 94... Canceling signal determining unit 96...Command signal generating section 98...Signal output section 106...First rotating body 108...Second rotating body

Claims

1. A grinding system that grinds a gear-shaped workpiece with a grinding tool by rotating the workpiece while meshing the workpiece with a spiral grinding tooth surface of the grinding tool, one of the workpiece and the grinding tool is a first rotating body; the other of the workpiece and the grinding tool is a second rotating body, a signal acquiring unit that acquires a first signal indicating a rotation speed of the first rotating body and a second signal indicating a rotation speed of the second rotating body; a synchronization signal generating unit that generates a synchronization signal for rotating the first rotating body synchronously with the second rotating body based on the first signal and the second signal; a command signal generating unit that generates a command signal based on a predetermined canceling signal for suppressing fluctuations in the rotational speed of the first rotor due to cogging of a motor that rotates the first rotor, and the synchronization signal; a signal output unit that outputs the command signal generated by the command signal generation unit to control the motor; Equipped with a canceling signal determiner that adjusts the phase and amplitude of a candidate signal that is a candidate for the canceling signal while the first rotating body and the second rotating body are rotating without meshing with each other, and acquires the first signal that indicates the rotational speed of the first rotating body, and determines, as the canceling signal, the candidate signal that minimizes the amount of fluctuation in the rotational speed of the first rotating body due to cogging while the first rotating body and the second rotating body are rotating without meshing with each other.

2. 10. The grinding system of claim 1, A grinding system, wherein the candidate signal is a sine wave having a frequency corresponding to a frequency of fluctuations in the rotational speed of the first rotating body due to the cogging.

3. 10. The grinding system of claim 1, The canceling signal determination unit a phase search unit that searches for an optimal phase of the candidate signal that minimizes the amount of variation by rotating the first rotor while changing the phase of the candidate signal while keeping the amplitude of the candidate signal constant; an amplitude search unit that searches for an optimal amplitude of the candidate signal that minimizes the amount of variation by rotating the first rotor while changing the amplitude of the candidate signal while maintaining the phase of the candidate signal at the optimal phase; A grinding system comprising:

4. The grinding system according to any one of claims 1 to 3, the first rotating body is the workpiece, The second rotating body is the grinding tool.

5. 1. A control method for a grinding system in which a gear-shaped workpiece and a grinding tool are meshed and rotated to grind a workpiece tooth surface of the workpiece with a spiral grinding tooth surface of the grinding tool, comprising: one of the workpiece and the grinding tool is a first rotating body; the other of the workpiece and the grinding tool is a second rotating body, a signal acquiring step of acquiring a first signal indicating a rotation speed of the first rotating body and a second signal indicating a rotation speed of the second rotating body; a synchronization signal generating step of generating a synchronization signal for rotating the first rotating body synchronously with the second rotating body based on the first signal and the second signal; a command signal generating step of generating a command signal based on the synchronization signal and a predetermined canceling signal for suppressing fluctuations in the rotational speed of the first rotor due to cogging of a motor that rotates the first rotor; a signal output step of outputting the command signal generated in the command signal generation step to control the motor; Equipped with a canceling signal determination step of adjusting a phase and amplitude of a candidate signal that is a candidate for the canceling signal while the first rotating body and the second rotating body are rotating without meshing with each other, and acquiring the first signal that indicates the rotational speed of the first rotating body, and determining, as the canceling signal, the candidate signal that minimizes the amount of fluctuation in the rotational speed of the first rotating body due to cogging while the first rotating body and the second rotating body are rotating without meshing with each other.

6. 6. A method for controlling a grinding system according to claim 5, comprising: A method for controlling a grinding system, wherein the candidate signal is a sine wave having a frequency corresponding to a frequency of fluctuations in the rotational speed of the first rotating body caused by the cogging.

7. 7. A method for controlling a grinding system according to claim 6, comprising: The canceling signal determining step includes: a phase search step of searching for an optimal phase of the candidate signal that minimizes the amount of variation by rotating the first rotor while changing the phase of the candidate signal while keeping the amplitude of the candidate signal constant; an amplitude search step of searching for an optimal amplitude of the candidate signal that minimizes the amount of variation by rotating the first rotor while changing the amplitude of the candidate signal while maintaining the phase of the candidate signal at the optimal phase; A method for controlling a grinding system, comprising:

8. A method for controlling a grinding system according to any one of claims 5 to 7, comprising: the first rotating body is the workpiece, The second rotating body is the grinding tool.

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