JP5219600B2 - Grinding wheel molding state determination device and grinding wheel molding state determination method - Google Patents

Description

  The present invention relates to a tool dresser that performs dressing by bringing a dresser into contact with a grindstone. The present invention relates to a method for determining a grinding wheel forming state.

  In a tool dresser that performs dressing by bringing a dresser into contact with a grindstone, an AE (Acoustic Emission) sensor is used for detecting contact between the grindstone and the dresser or detecting completion of dressing. There are various types of AE sensors depending on the target frequency, but AE sensors used in processing devices such as grinding machines and dressing devices target piezoelectric regions of several tens of kHz to several hundreds of MHz. It is composed of elements.

  For AE sensors, NDIS No. Since the grinding machines using the AE sensor, such as 2106-79 and 2106-91, are widely known as described in Patent Document 1 and the like, the detailed explanation of the AE sensor and the dressing device is here. Only the portions directly related to the present invention will be described.

JP-A-6-114692 JP 7-164319 A JP-A-9-216158 Japanese Patent Laid-Open No. 11-235665

  By monitoring the AE signal generated during the dressing operation, it is possible to determine the suitability of the grindstone shape. When the rotating grindstone is brought into contact with the dresser, the peripheral speed of the contact portion increases as the cross-sectional diameter of the portion of the grindstone in contact with the dresser increases. For this reason, the AE signal is strong when the dresser is in contact with a portion having a large cross-sectional diameter of the grindstone, and the AE signal is weak when the dresser is in contact with a portion having a small cross-sectional diameter of the grindstone. Therefore, if the AE signal is detected while moving the dresser in the direction of the rotation axis of the grindstone along the circumferential shape of the grindstone, the strength of the AE signal changes according to the cross-sectional diameter of the grindstone.

In a conventional dressing operation, an AE signal output from an AE sensor is displayed on a monitor, and a person monitors the grinding wheel shape determined from the AE signal appearing on the monitor, thereby determining whether dressing is complete or whether there is a dresser abnormality. Had gone. For this reason, skill is required for the dressing operation, and the dressing accuracy of the grindstone varies depending on the operator, and as a result, the quality of products processed using the grindstone may be deteriorated.
In view of the above circumstances, an object of the present invention is to enable an expert to dress a grindstone appropriately.

  In order to achieve the above object, according to the present invention, an elastic wave generated when a reference grindstone is dressed by performing a predetermined relative motion using a reference dresser is detected by the AE sensor, and at this time, it is output from the AE sensor. Is stored as a master signal waveform. Next, a measurement signal waveform is acquired by detecting an elastic wave generated by dressing the target grindstone and the target dresser for determining the grinding wheel forming state while performing the same motion as the predetermined relative motion. Then, by determining whether or not the difference between the measurement signal waveform and the master signal waveform stored in advance is within a predetermined threshold range, the grindstone forming state of the target grindstone is determined.

  When the difference between the measurement signal waveform and the master signal waveform is compared with the threshold range, a plurality of grinding wheel forming states may be detected by comparing whether or not the difference is within the plurality of threshold ranges.

By comparing the difference between the master signal stored in advance and the measurement signal waveform with the threshold range, it is possible to easily determine the grinding wheel molding state even when the strength of the AE signal changes due to the difference in the cross-sectional diameter of the grinding wheel. .
By comparing with a plurality of threshold ranges, for example, dressing completion determination and dresser wear detection can be performed simultaneously.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing an overall configuration of a dressing apparatus according to an embodiment of the present invention. The dressing apparatus 1 relatively moves the grindstone rotating section 11 that rotates the grindstone 10 about the axis A1, the dresser rotating section 13 that rotates the dresser 12 about the axis A2 as the rotation axis, and the dresser 12 relative to the grindstone 10. A dresser moving unit 14 is provided.

FIG. 2 is an enlarged view of portions of the grindstone 10 and the dresser 12 in FIG. In the grindstone 10 illustrated in FIG. 2, the dressing surface 10a has a conical shape. When performing dressing, the dresser 12 moves in the direction of the axis of rotation A1 of the grindstone along the dressing surface 10a by the dresser moving portion 14 shown in FIG. 1 while contacting the grindstone 10.
Note that the determination of the grinding wheel forming state between the grinding wheel and the dresser according to the present invention can be applied to the grinding stone 10 having various shapes, and is not specified to the grinding stone 10 having a specific shape. However, in the present specification, for the sake of simplicity, the following description will be given by exemplifying the grindstone 10 in which the dressing surface 10a has a conical shape.

The dressing apparatus 1 also includes a control unit 15 that controls operations of the grindstone rotating unit 11, the dresser rotating unit 13, and the dresser moving unit 14. The control unit 15 may be a numerical control (NC) device, for example.
An AE (Acoustic Emission) sensor 21 is attached to the casing of the dresser rotating unit 13, and AE waves generated by grinding of the grindstone 10 and the dresser 12 are transmitted to the AE sensor 21 through the casing, and the AE sensor 21 is AE. Generate a signal. The dressing apparatus 1 includes a grindstone forming state determination unit 20 that processes the AE signal to determine whether dressing of the grindstone 10 is complete or whether the dresser 12 is in good or bad condition.
The display unit 16 is used to display an operation screen for operation of the control unit 15, a device state of the dressing apparatus 1, and a quality of the dressing state of the grindstone 10.

  FIG. 3 is a block diagram illustrating a schematic configuration of the grindstone molding state determination unit 20 illustrated in FIG. 1. The grinding wheel molding state determination unit 20 includes an amplifier 22 that amplifies the AE signal input from the AE sensor 21 to a predetermined intensity, an A / D converter 23 that converts the analog signal output from the amplifier 22 into a digital AE signal, A storage unit 25 for storing the signal waveform digitized by the A / D converter 23 as a master signal waveform, a measurement signal waveform that is an AE signal waveform detected during actual dressing, and a storage unit 25 stored in advance. A waveform comparison unit 26 for comparing the master signal waveform, and a determination result indicating signal indicating the result of determining the grinding wheel forming state between the grindstone 10 and the dresser 12 according to the comparison result by the waveform comparison unit 26 and the control unit. 15 has a determination unit 27 that outputs the data to 15.

  Further, the grinding wheel molding state determination unit 20 operates whether the grinding wheel molding state determination unit 20 operates in the “determination mode” in which the determination unit 27 determines the grinding wheel molding state, or stores a master signal waveform in the memory 25 “master storage”. A mode determination unit 28 that determines whether the grinding wheel molding state determination unit 20 operates in the “mode” is provided. For example, the mode determination unit 28 may determine the operation mode according to the state of a switch provided in the grindstone molding state determination unit 20, or may determine the operation mode according to the control from the control unit 15.

  The grinding wheel molding state determination unit 20 controls which of the memory 25 and the waveform comparison unit 26 outputs the digital AE signal output from the A / D converter 23 in accordance with the operation mode determined by the mode determination unit 28. A signal processing unit 24 is provided. The signal processing unit 24 stores the digital AE signal in the memory 25 when in the “master storage mode”, and outputs the digital AE signal to the waveform comparison unit 26 when in the “determination mode”.

  FIG. 4 is an explanatory diagram of dressing of a grindstone having a conical shape. At the time of dressing, first, the dresser 12 is brought close to the dressing surface 10a of the grindstone 10 to some extent, then from point a to point b, from point b to point c, from point c to point d, from point d. The cycle of moving the dresser 12 to the point a is repeated.

First, the dresser 12 is fed by a predetermined amount in a direction from the point a to the point b, that is, in a direction orthogonal to the dressing surface 10a and approaching the dressing surface 10a of the grindstone 10. Next, the dresser 12 is fed at a constant speed from the tip of the grindstone toward the base end in the direction from the point b to the point c along the dressing surface 10a. When the dresser 12 reaches the base end, the direction from the point a to the point b is reached. The dresser 12 is sent in the direction from the point c to the point d opposite to the point d, and the direction from the point d to the point a opposite to the direction from the point b to the point c is sent.
Here, by setting the feed amount of the dresser from the point a to the point b longer by the predetermined length Δd than the feed amount from the point c to the point d, the grindstone 10 by the predetermined length Δd by one cycle (dressing cycle). The dressing 10a is dressed.

FIG. 5 is a diagram showing a waveform of an AE signal output during one-cycle dressing shown in FIG. When the dresser 12 at the point a shown in FIG. 4 at the time ta1 reaches the point b at the time tb1, the dresser 12 and the grindstone 10 come into contact with each other, so that an AE signal is generated. Thereafter, as the dresser 12 is sent from the tip of the grindstone toward the base end in the direction from the point b to the point c, the cross-sectional diameter of the grindstone 10 at the contact portion between the dresser 12 and the grindstone 10 increases, so the AE signal also increases.
When the dresser 12 reaches the point c at time tc1, the generation of the AE signal is stopped because the dresser 12 and the grindstone 10 are separated from each other. Thereafter, the dresser 12 reaches the point d at the time td1, and the dresser 12 reaches the point a at the time ta2. Therefore, the times ta1 to ta2 correspond to one dressing cycle.

  If the speed at which the dresser 12 is fed is the same during each cycle, the time ΔTc required for one cycle is equal in each cycle. Therefore, when the control unit 15 controls the dresser moving unit 14 to move the dresser 12 on the path passing through the point abcda, the control unit 15 is at the time tr when the dresser 12 reaches the same point on the path. When the timing signal is output, the interval ΔT between the output time tr of the timing signal and the rising time tb1 of the AE signal is always equal.

The signal processing unit 24 shown in FIG. 3 can synchronize the master signal waveform stored in the memory 25 and the AE signal waveform measured during dressing by the timing signal output from the control unit 15.
For example, the signal processing unit 24 uses the timing signal as a reference to collect a master signal waveform in one cycle for dressing the grindstone 10 to collect the master signal waveform, and in each cycle in the actual dressing operation of the grindstone 10. By matching the sampling period of the measurement signal waveform in FIG. 5, synchronization between the master signal waveform compared with the waveform comparison unit 26 and the measurement signal waveform can be performed.

Alternatively, the signal processing unit 24 inputs a feed amount signal indicating the feed amount of the dresser 12 instructed from the control unit 15 to the dresser moving unit 14 from the control unit 15, and the master signal waveform stored in the memory 25 and the waveform comparison unit Synchronization between the master signal waveform compared at 26 and the measured signal waveform compared may be performed.
Alternatively, the signal processing unit 24 inputs a measurement signal waveform of a certain length period, and then performs pattern matching between the measurement signal waveform and the master signal waveform of this period, whereby the master signal to be compared in the waveform comparison unit 26 You may synchronize between a waveform and a measurement signal waveform.

FIG. 6 is a flowchart showing a first example of the dressing completion determination method according to the embodiment of the present invention. In step S <b> 1, the signal processing unit 24 illustrated in FIG. 3 stores the master signal waveform of the AE signal output from the AE sensor 21 in the memory 25.
When the operation mode of the grinding wheel molding state determination unit 20 is designated as “master storage mode” by an operation from the operator or control from the control unit 15, the mode determination unit 28 sets the current operation mode to “master storage mode”. Is output to the signal processing unit 24. The signal processing unit 24 that has received the mode setting signal stores the digitized AE signal waveform input from the A / D converter 23 in the memory 25.

  At this time, the grindstone rotating part 11 is equipped with a grindstone 10 having already been dressed and having a desired shape as a reference grindstone. The dresser rotating unit 13 is also equipped with a dresser 12 in a desired state as a reference dresser. Then, the same processing as the dressing is performed on the reference grindstone 10 using the reference dresser 12, and the AE signal generated at this time is stored in the memory 25. FIG. 7A shows an example of a master signal waveform.

  When the operation mode of the grinding wheel molding state determination unit 20 is designated as “determination mode” by an operation from the operator or control from the processing machine control device 12, the mode determination unit 28 determines that the current operation mode is “determination”. A mode setting signal indicating “mode” is output to the signal processing unit 24. In addition, after receiving this mode setting signal, the signal processing unit 24 outputs the digitized AE signal waveform input from the A / D converter 23 to the waveform comparison unit 26.

  In step S2 of FIG. 6, an actual dressing process is performed on the grindstone 10 using the dresser 12, and an elastic wave generated at that time is detected by the AE sensor 21, and an AE signal is generated. A measurement signal waveform digitized by the D converter 23 is acquired. The acquired measurement signal waveform is output from the signal processing unit 24 to the waveform comparison unit 26. FIG. 7B shows an example of a measurement signal waveform.

  In step S <b> 3, the waveform comparison unit 26 reads the master signal waveform stored in step S <b> 1 from the memory 25 and generates a difference signal from the measurement signal waveform input from the signal processing unit 24. The measurement signal waveform output from the signal processing unit 24 to the waveform comparison unit 26 is synchronized with the master signal waveform read from the memory 25 to the waveform comparison unit 26 in accordance with the method described above by the signal processing unit 24. Yes. FIG. 7C shows a difference signal between FIG. 7A and FIG. 7B.

  In step S4, it is determined whether or not the difference signal between the master signal waveform and the measurement signal waveform is within a predetermined threshold range R1 (T1l ≦ x ≦ T1h). When the value of the difference signal is not within the threshold range R1, in step S5, the grinding wheel forming state of the grindstone 10 and the dresser 12 is abnormal, the wear of the dresser 12, the abnormal shape of the grindstone, the dressing device 1, etc. It is determined that there is some abnormality, and a determination result instruction signal indicating an abnormal state is output to the control unit 15.

  In step S6, it is determined whether or not the difference signal is within a predetermined threshold range R2 (T2l ≦ x ≦ T2h) that is narrower than R1 within the threshold range R1. When all the difference signal values calculated within one dressing cycle are within the threshold range R2, in step S7, the grindstone forming state of the grindstone 10 and the dresser 12 is good, and the dressing of the grindstone 10 is completed. A determination result instruction signal indicating completion of dressing is output to the control unit 15. When the value of the difference signal does not fall within the threshold range R2, it is determined that the dressing of the grindstone 10 has not been completed, and the process returns to step S2.

FIG. 8 is a flowchart showing a second example of the dressing completion determination method according to the embodiment of the present invention. In step S1, the master signal waveform is stored in the memory 25 as in step S1 shown in FIG. FIG. 9A shows an example of a master signal waveform.
In step S10, the grindstone 10 is dressed by repeating a cycle of moving the dresser 12 along the path abcda shown in FIG. 4 a predetermined number of times. Here, the predetermined number of times, that is, the number of cycles for performing dressing is, for example, the number of dressing cycles expected to be required for completion of dressing of the grindstone 10 when the grindstone 10 is usually dressed at a normal frequency. Good.
In step S2, a measurement signal waveform is acquired as in step S2 shown in FIG. FIG. 9B shows an example of a measurement signal waveform.

In step S3, the waveform comparison unit 26 reads the master signal waveform stored in step S1 from the memory 25 and outputs a difference signal from the measurement signal waveform input from the signal processing unit 24, as in step S2 shown in FIG. Generate. FIG. 9C shows a difference signal between FIG. 9A and FIG. 9B.
In step S4, it is determined whether or not the difference signal between the master signal waveform and the measurement signal waveform is within a predetermined threshold range R1. When the value of the difference signal is not within the threshold range R1, it is determined that there is some abnormality between the grindstone 10 and the dresser 12, as in step S5 shown in FIG. 6, and a determination result instruction signal indicating an abnormal state is provided. Output to the control unit 15.

  In step S6, it is determined whether or not the difference signal is within a predetermined threshold range R2 that is narrower than R1 within the threshold range R1. When all the difference signal values calculated within one dressing cycle are within the threshold range R2, it is determined that the dressing of the grindstone 10 is completed as in step S7 shown in FIG. The result instruction signal is output to the control unit 15. When the value of the difference signal does not fall within the threshold range R2, it is determined that the grindstone 10 is dressed in a prescribed shape, but the dresser 12 is worn, and it is time to replace the dresser 12. The result instruction signal is output to the control unit 15.

  INDUSTRIAL APPLICABILITY The present invention can be used for a tool dresser that performs dressing by bringing a dresser into contact with a grindstone.

It is a figure which shows the whole structure of the dressing apparatus by the Example of this invention. It is an enlarged view of the part of the grindstone and dresser in FIG. It is a block diagram which shows schematic structure of the grindstone shaping | molding state determination part shown in FIG. It is explanatory drawing of dressing of the grindstone which has a cone shape. It is a figure which shows the waveform of the AE signal output in the case of dressing of 1 cycle shown in FIG. It is a flowchart which shows the 1st example of the dressing completion determination method by the Example of this invention. (A) is a waveform diagram showing an example of a master signal waveform, (B) is a waveform diagram showing an example of a measurement signal waveform, and (C) is (A) and (B) in the determination method shown in FIG. It is a figure explaining the comparison with the difference signal and threshold value range. It is a flowchart which shows the 2nd example of the dressing completion determination method by the Example of this invention. (A) is a waveform diagram showing an example of a master signal waveform, (B) is a waveform diagram showing an example of a measurement signal waveform, and (C) is (A) and (B) in the determination method shown in FIG. It is a figure explaining the comparison with the difference signal and threshold value range.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dressing apparatus 10 Grinding wheel 10a Dressing surface 11 Grinding wheel rotating part 12 Dresser 13 Dresser rotating part 14 Dresser moving part 21 AE sensor

Claims (2)

A grindstone molding state determination device that determines a grindstone molding state between the grindstone and the dresser while performing dressing by bringing a dresser into contact with the grindstone,
An AE sensor that detects an elastic wave generated when the grindstone and the dresser are formed into a grindstone;
A storage unit for storing a signal waveform output from the AE sensor as a master signal waveform when dressing by performing a predetermined relative motion while contacting a reference grindstone and a reference dresser;
The measurement signal waveform output from the AE sensor and the master signal waveform stored in advance when dressing the target grindstone and the target dresser to be subjected to the same motion as the predetermined relative motion to determine the grinding wheel forming state A determination unit for determining a grinding wheel molding state between the target grindstone and the target dresser by determining whether or not the magnitude of the signal intensity difference is within a predetermined threshold range;
Bei to give a,
The determination unit determines that dressing is completed when the magnitude of the signal intensity difference is smaller than a first threshold, and the target grindstone when the magnitude of the signal intensity difference is larger than a second threshold. It is determined that the shape of the object is abnormal or that the target dresser is worn . A grindstone molding state determination method for determining a grindstone molding state between the grindstone and the dresser while performing dressing by bringing a dresser into contact with a grindstone,
A first detection step of detecting, with an AE sensor, an elastic wave generated when dressing by performing a predetermined relative motion while grinding a reference grindstone and a reference dresser;
Storing a signal waveform output from the AE sensor in the first detection step as a master signal waveform;
A second detection step of detecting, by the AE sensor, an elastic wave that is generated when dressing the target grindstone and the target dresser to be subjected to the same motion as the predetermined relative motion to determine the grinding wheel forming state;
Whether or not the difference in magnitude of the signal intensity difference between the measurement signal waveform output from the AE sensor in the second detection step and the master signal waveform stored in advance is within a predetermined threshold range. by determining, seen including and a judgment step of judging grindstone molded state between the target grinding wheel and the object dresser,
In the determination step, it is determined that dressing is completed when the magnitude of the signal intensity difference is smaller than a first threshold, and when the magnitude of the signal intensity difference is larger than a second threshold, the target grindstone A method for determining a grindstone molding state, wherein the shape of the wheel is abnormal or the target dresser is determined to be worn .

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