JP2002066879A - Acoustic emission detecting device for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the execution of high precise detection through comparative ly simple constitution. SOLUTION: When a dresser tool 3 makes contact with a grinding wheel 6, a voltage is generated at a ultrasonic sensor 13. A voltage is induced to a receiving coil 14 by a magnetic field and the generation of a ultrasonic wave can be detected thereby. Different from a conventional type, there is no need for delicate distance regulation between a transmission coil 11 and a receiving coil 14 and reliable detection of a ultrasonic wave is practicable through comparatively simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting acoustic emission (ultrasonic waves) generated at the time of contact between a processing tool and a work in a machine tool and contact between a processing tool and a dresser. The present invention relates to a device which is suitable for a grinding machine or a dresser device and which improves detection accuracy and the like.

[0002]

2. Description of the Related Art Conventionally, as this type of apparatus, for example,
As disclosed in Japanese Patent Publication No. 1-23273, a liquid film for transmitting an ultrasonic signal is formed between a dresser and a housing on which the dresser shaft is supported, and the dresser is acoustically coupled. That can surely catch the contact between the wheel and the grindstone is disclosed.

[0003]

However, in the above-described conventional apparatus, by transmitting the ultrasonic wave through the liquid film, the attenuation of the ultrasonic wave at the time of transmission can be reduced, and the detection with high sensitivity can be performed. Although it is possible, it becomes necessary to control the flow rate of the detection liquid used for forming the liquid film, to set the gap for forming the liquid film, and to use a filter for the detection liquid and an auxiliary device such as a flow meter. Therefore, simpler and less expensive detectors have been desired. The present invention has been made in view of the above circumstances, has a relatively simple configuration, and
An object of the present invention is to provide an acoustic emission detection device for a machine tool which does not require various operations and auxiliary equipments when used. Another object of the present invention is to provide an acoustic emission detection device for a machine tool capable of performing highly accurate detection.

[0004]

In order to achieve the object of the present invention, an acoustic emission detecting device for a machine tool according to the present invention has a tool which is rotated.
Acoustic emission for a machine tool configured to be able to determine the contact between the tool and the workpiece in a machine tool that processes the workpiece with the tool by detecting ultrasonic waves generated by the contact. A detection device, wherein an ultrasonic sensor is provided on the tool or a rotating shaft for rotating the tool, and a transmission coil connected in series with the ultrasonic sensor is provided, while fixing the machine tool facing the transmission coil. A receiving coil is provided in the portion thus set, and a voltage induced in the receiving coil can be output to the outside.

In such a configuration, a voltage is generated in the ultrasonic sensor due to the contact between the tool and the workpiece, and a current flows through a transmitting coil connected to the ultrasonic sensor to generate a magnetic field. Since a voltage is induced in the receiving coil, it is possible to know the generation of the ultrasonic wave. Since the transmission of the signal obtained by the ultrasonic sensor utilizes the electromagnetic coupling between the transmitting coil and the receiving coil, unlike the conventional method, fine adjustment of the distance between the two is not required, and No special tools are required, and the ultrasonic wave can be reliably detected with a relatively simple configuration.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The members, arrangements, and the like described below do not limit the present invention, and can be variously modified within the scope of the present invention. First, an acoustic emission detecting device S for a machine tool according to an embodiment of the first invention is described.
1 will be described with reference to FIGS. 1 and 2. The configuration example shown in FIGS. 1 and 2 is an example in the case where it is provided in a so-called dressing device. That is, a spindle 2 is accommodated in a housing 1 fixedly mounted on a fixed base (not shown), and a part of the spindle 2 projects from the housing 1. Has a dresser tool 3 fixed thereto (see FIG. 1). A fixed portion 4 is provided between the housing 1 and the dresser tool 3 so as to be fixed to the housing 1 so that the spindle 2 passes through the center of the fixed portion 4 (see FIG. 1).

The fixing portion 4 is made of a member formed in a cylindrical shape with a short bottom in the axial direction, and the spindle 2 penetrates the center of the bottom portion. The part side is provided so as to face the dresser tool 3 with an appropriate gap therebetween (see FIG. 1). A receiving unit 102 is provided in the opening of the fixing portion 4 as described later (see FIG. 1). The dresser tool 3 according to the embodiment of the present invention has a known / well-known configuration in that, for example, a dresser body 3a made of diamond or the like is formed in an annular shape on the outer peripheral surface of a disk member 3b. Is the same as In the embodiment of the present invention, a concave portion 5 is further formed on one surface side of the disk member 3b, that is, on a surface side facing the fixed portion 4, and the transmitting unit 101 is provided in the concave portion 5 as described later. (See FIGS. 1 and 2). And
In the vicinity of the dresser tool 3, a grindstone 6 as a workpiece is attached to a support shaft 7 and is rotatably supported, and moves in the axial direction of the support shaft 7 and in a direction orthogonal to the support shaft 7. It is provided as possible.
The moving mechanism of the grindstone 6 is not an essential part of the present invention, so that illustration and detailed description thereof are omitted.

A transmitting unit 101 provided on the dresser tool 3 and a receiving unit 102 provided on the fixed part 4 constitute an acoustic emission detecting device S1 for a machine tool. First, the transmitting unit 101 provided in the concave portion 5 of the disk member 3b of the dresser tool 3 includes a transmitting coil 11 wound around a transmitting ferrite core 12, and a closed circuit electrically connected to the transmitting coil 11. An AE (acoustic emission) sensor 13 to be formed is configured as a main component (see FIGS. 1 and 2). The transmitting ferrite core 12 is formed in an annular member having a through hole formed in the center portion, and the diameter of the through hole 12 a is set to be larger than that of the spindle 2. The transmission ferrite core 12 is joined and fixed to the bottom of the recess 5 of the dresser tool 3 with the spindle 2 loosely inserted into the through hole 12a. In the embodiment of the present invention, the center of the transmission ferrite core 12 formed on the annular member is disposed so as to substantially coincide with the center axis of the spindle 2 (FIG. 1). And FIG. 2).

The transmitting coil 11 is wound around the outer peripheral surface of the transmitting ferrite core 12. The transmission coil 11 shown in FIGS.
Is wound a plurality of times, but the number of turns need not be limited to a specific number of turns.
That is, in order to obtain high electromagnetic coupling with the receiving coil 14 as described later, it is preferable that the number of turns be larger. A
The E sensor (ultrasonic sensor) 13 has a known / well-known configuration using, for example, a piezoelectric element or the like. In the embodiment of the present invention, the concave portion 5 of the disk member 3b is used.
, Is provided at an appropriate position on the peripheral wall surface (see FIGS. 1 and 2). In other words, the location where the AE sensor 13 is disposed is preferably a location as close as possible to the location where the ultrasonic wave is generated, that is, a location as close as possible to the contact point between the dresser tool 3 and the grindstone 6. And the transmission coil 1
The AE sensor 1 and the AE sensor 13 are connected in series to form a series circuit like the equivalent circuit shown in FIG.

On the other hand, the receiving unit 102 provided on the fixed part 4 has a receiving coil 14 wound around a ferrite core 15 for reception. The ferrite core 15 for reception uses an annular member like the ferrite core 12 for transmission, and the spindle 2 is loosely inserted into the through-hole 15a, and is fixed to the fixing part 4 at a portion (not shown). , Only the spindle 2 is rotatable. The connection coil 16 is connected to the reception coil 14 wound around the reception ferrite core 15, so that a signal obtained by the reception coil 14 can be output to the outside as described later. . Actually, the connection wiring 16 is connected to a signal processing circuit 103 described later (see FIG. 3). The receiving coil 14 is wound a plurality of times in the same manner as the transmitting coil 11, but the number of turns need not be limited to a specific number.

FIG. 4 shows an example of the configuration of the signal processing circuit 103. The signal processing circuit 103 will be described below with reference to FIG. First, the signal processing circuit 1
Numeral 03 denotes a preamplifier 21, a first amplifier (expressed as “AMP (1)” in FIG. 4) 22, a high-pass filter (expressed as “HPF” in FIG. 4) 23, and a low-pass filter (In FIG. 4, it is described as “LPF”) 24
, A rectifier circuit 25, a second amplifier (denoted as “AMP (2)” in FIG. 4) 26, and a determination circuit 27. The preamplifier 21 is an amplifier circuit having a well-known and well-known circuit configuration for improving the S / N of the input signal and amplifying the input signal to a signal level suitable for amplification by the first amplifier 22. is there.
The first amplifier 22 is an amplifier circuit having a known / well-known circuit configuration for amplifying a signal from the preamplifier 21 to a level suitable for processing in a subsequent circuit and outputting the amplified signal.

The high-pass filter 23 is a filter having a well-known and well-known circuit configuration for removing unnecessary predetermined high-frequency components.
Is a filter having a well-known and well-known circuit configuration for removing unnecessary predetermined low-frequency components. The reason for using the high-pass filter 23 and the low-pass filter 24 in the signal processing circuit 103 is that the signal output from the AE sensor 13 includes, in addition to the AE wave generated by the contact between the dresser tool 3 and the grindstone 6, a dressing device. In this case, since a signal caused by mechanical vibration due to rotation or the like may be superimposed, such an unnecessary signal is removed. The rectifier circuit 25 is used to rectify the signal that has passed through the preamplifier 21, the first amplifier 22, the high-pass filter 23, and the low-pass filter 24 to suppress unnecessary fluctuation components, and to smooth the signal. It has a circuit configuration of The second amplifier 26 is for amplifying a signal output from the rectifier circuit 25 to an appropriate level, and is an amplifier circuit having a known / well-known circuit configuration. The discrimination circuit 27 compares the signal from the second amplifier 26 with a predetermined reference value.
6 is configured to output a predetermined signal assuming that an AE wave has been detected when the signal from 6 exceeds a reference value.

Next, the operation of the above configuration will be described. First, when the rotation of the dresser tool 3 is started for dressing, the grindstone 6 is gradually approached to the dresser tool 3 by a moving mechanism (not shown). When the dresser body 3a and the grindstone 6 come into contact with each other, an AE wave is generated at the contact point, which is transmitted to the disk member 3b of the dresser tool 3 and transmitted to the AE sensor 13 (black arrow in FIG. 1). In the sensor 13, a voltage corresponding to the intensity of the AE wave transmitted via the disk member 3b is generated. As a result, a current flows through the transmission coil 11 connected to the AE sensor 13, so that a magnetic field is generated near the transmission coil 11. Then, due to the electromagnetic coupling between the receiving coil 14 and the transmitting coil 11 provided in the fixed unit 4, a voltage is induced in the receiving coil 14 according to the magnitude of the magnetic field generated in the transmitting coil 11.
That is, a voltage corresponding to the AE wave is induced in the receiving coil 14, and a voltage signal corresponding to the AE wave is obtained in the receiving coil 14. In FIG. 1, the arrow between the fixed part 4 and the dresser tool 3 indicates the transmission coil 11.
4 schematically shows a state in which electromagnetic coupling has occurred between the receiving coil 14 and the receiving coil 14.

The voltage signal induced in the receiving coil 14 is
Unnecessary signals other than AE waves are input to the signal processing circuit 103 and removed and amplified to improve the S / N ratio.
A predetermined signal is output assuming that the generation of a wave, in other words, the contact between the dresser tool 3 and the grindstone 6 has occurred. The output of the predetermined signal from the determination circuit 27 is
By using it for the position control of the grindstone 6, the dressing start point can be accurately determined, and the position control can be further improved in accuracy. FIG. 5 shows an example of a voltage signal corresponding to the AE wave obtained by the second amplifier 26. The noise level is extremely low, approximately 0.08 V, whereas the noise level is very low. The level of the applied voltage signal is approximately 2.67 V at the peak, and it can be confirmed that a signal having a high S / N can be obtained.

Next, another example of the coil arrangement will be described with reference to FIG.
This will be described with reference to FIG. The same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. Hereinafter, different points will be mainly described. FIG. 6 shows a state in which the dresser tool 3 is viewed in a cross section taken along line AA of FIG. In the configuration examples shown in FIGS. 1 and 2 described above, the transmission coil 11 and the reception coil 14 have a configuration in which one coil is provided. In the case where space cannot be secured, a configuration in which a number of relatively small coils are provided may be adopted. Less than,
More specifically, FIG. 6 shows an example of the arrangement of a plurality of coils in the recess 5 of the dresser tool 3.
In this example, first to fourth transmission coils 11a to 11d are arranged on the peripheral portion of the concave portion 5.

That is, the first to fourth transmission ferrite cores 31a to 31d formed on the annular member are provided at appropriate intervals in the circumferential direction at the peripheral portion of the concave portion 5. The first to fourth transmission ferrite cores 31a to 31d are provided on the outer peripheral surfaces thereof.
Are wound and attached, respectively. AE sensor 13
1 is joined to an appropriate position on the peripheral wall surface of the concave portion 5 similarly to the case of the configuration example shown in FIGS. 1 and 2. In this configuration example, the first to fourth transmission coils 11a to 11d are connected in series, connected to the AE sensor 13, and a series circuit of the first to fourth transmission coils 11a to 11d and the AE sensor 13 is formed. It is configured.

On the other hand, in this case, it is preferable that the fixed portion 4 side (see FIG. 1) also has a configuration in which a plurality of receiving coils (not shown) are arranged, similarly to the configuration shown in FIG. In that case, the number of coils does not necessarily need to match that of the transmitting unit 101A. The plurality of receiving coils may be connected in series or in parallel as in the case of the first to fourth transmitting coils 11a to 11d. The plurality of receiving coils are connected to the signal processing circuit 103 (see FIG. 4) in the same manner as in the configuration examples shown in FIGS. The operation of detecting the AE signal in such a configuration is basically the same as that described in the configuration examples shown in FIGS. 1 to 4, and thus the description thereof will not be repeated here. .

Next, an acoustic emission detecting device S2 for a machine tool according to the second embodiment of the present invention.
Will be described with reference to FIG. In addition,
The same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.
Hereinafter, different points will be mainly described. In the configuration examples shown in FIGS. 1 and 2 described above, the space for storing the transmission coil 11 and the like in the dresser tool 3 and the space for storing the reception coil 14 and the like in the fixed portion 4 are respectively the original. It can be said that it is formed so that the external dimensions are not changed. On the other hand, in the configuration example according to the second embodiment of the present invention, the storage space is provided in the dresser tool 3. The transmitting unit 101B is externally attached without performing any processing for forming the receiving unit 102B so as to face the transmitting unit 101B.
Is provided.

That is, the disk member 3b of the dresser tool 3
, A transmission unit 101B is provided substantially at the center of a plane side opposite to the plane side facing the housing 1. In this configuration example, the transmission unit 101B has a transmission storage body 41 formed in a cylindrical shape.
The transmission coil 42, the AE sensor 13, and the like are housed inside. The transmitting housing 41 has one end joined and fixed to the dresser tool 3. The AE sensor 13 is fixed so as to be directly joined to the surface of the dresser tool 3 inside the housing 41 for transmission. On the other hand, the transmission coil 42 is
It is wound around 3. That is, the transmission ferrite core 43 has a relatively short columnar portion 43a and disk portions 43b and 43c formed on both end surfaces thereof, respectively.
The transmission coil 42 is wound around the cylindrical portion 43a. In this configuration example, the transmission ferrite core 43 is fixed to the transmission housing 41 by a support member (not shown) such that the center axis of the cylindrical portion 43a and the center axis of the spindle 2 substantially coincide with each other. It has become. In other words, the transmission coil 42 is arranged concentrically around the center axis of the spindle 2. Note that the transmission coil 42 and the AE sensor 13 are
2 and are connected in series similarly to the configuration example shown in FIG. 2 to form a series circuit.

On the other hand, the receiving unit 102B is provided on the fixed bracket 47 so as to face the above-mentioned transmitting unit 101B at an appropriate interval.
That is, first, the fixing bracket 47 is made of a member having a flat portion, and is fixed to an appropriate fixed portion (not shown) of the dressing device so that the flat portion is parallel to the dresser tool 3. It is provided by. The receiving unit 102B has a receiving housing 44 formed in a bottomed cylindrical shape, the center axis of which is substantially coincident with the center axis of the spindle 2 which rotates the dresser tool 3, and the bottom side is a fixed bracket. It is joined and fixed to a flat portion 47. As in the case of the transmission ferrite core 43, the disk portions 46a are provided at both ends of the cylindrical portion 46a.
b, 46c, the receiving ferrite core 46
The column 46a is fixed to the receiving container 44 by a support member (not shown) so that the center axis of the column portion 46a and the center axis of the spindle 2 substantially coincide with each other.

The receiving coil 45 is wound around a cylindrical portion 46a of a receiving ferrite core 46, and connection wires 16A are connected to both ends thereof.
5 is input to the signal processing circuit 103 (see FIG. 4) via the connection wiring 16A. With such an arrangement, the transmission coil 42 and the reception coil 45 face each other with an appropriate gap therebetween, and electromagnetic coupling occurs between the two. In the case of this configuration example, since the transmission unit 101B is attached to the dresser tool 3 facing outward, and the reception unit 102B is provided to face the transmission unit 101B, the fixing bracket 4
7 is newly provided, and a new space L between the fixing bracket 47 and the dresser tool 3 is secured.
(See FIG. 7), which is relatively suitable when there is room in the arrangement and structure of each part of the dresser device. Note that the operation of detecting the AE signal in the configuration shown in FIG. 7 is basically the same as that described in the configuration examples shown in FIGS. 1 to 4, and thus the description thereof will not be repeated here. It shall be.

In each of the above-described configuration examples, the contact between the dresser tool 3 and the grindstone 6 in the dressing device is performed by AE.
AE generated by the contact between the grindstone and the grinding object (work) in the grinding machine
The same applies to the case of detecting a wave. That is, in the configuration example shown in FIGS. 1 and 2, when the grindstone 6 is provided on a grinding machine, the grindstone 6 is attached to the support shaft 7 via a not-shown base. The transmission coils 11 and A are provided at appropriate portions of the base metal portion or at appropriate portions of the support shaft 7 which is a rotating shaft in the same manner as provided on the dresser tool 3 shown in FIGS.
An E sensor 13 and the like are provided. On the other hand, a receiving coil 14 may be provided at an appropriate portion to which a ground object (not shown) is fixed in the same manner as provided on the fixing portion 4 in FIG. Of course, even in the case of a grindstone and a grinding object (work) in a grinding machine, it is not necessary to be limited to the above-described configuration, as in the case of the above-mentioned dressing apparatus, and as shown in FIG. The configuration and the configuration as shown in FIG. 7 may be appropriately applied.

Further, by appropriately adjusting the number of turns and the size of the transmission coil 11 and the reception coil 14 so as to tune to a predetermined frequency, that is, a main frequency component of the ultrasonic wave desired to be detected, It is possible to increase the detection accuracy. This is because the other transmission coils 11a to 11a
The same applies to d and 42 and the receiving coil 45.

[0024]

As described above, according to the present invention, a signal obtained by an ultrasonic sensor in response to generation of an ultrasonic wave can be transmitted using electromagnetic coupling between two coils. With this configuration, unlike conventional devices that transmit ultrasonic waves themselves through a liquid film, there is no need for fine adjustment of the distance between the two coils as in the past, and no need for auxiliary tools. In addition, the present invention has an effect that the ultrasonic wave can be detected reliably and accurately with a relatively simple configuration. Further, unlike the conventional apparatus using a liquid film, transmission of so-called idling noise is hardly performed, so that detection with less noise is possible. Furthermore, since it is easy to improve the sensitivity to a specific frequency by adjusting the number of turns and the size of the coil, the detection accuracy can be improved by matching the frequency characteristics of the coil with the main frequency components of ultrasonic waves. Therefore, it is possible to provide an apparatus having a high performance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram including a partial vertical cross section showing a configuration example of an acoustic emission detection device for a machine tool according to an embodiment of the first invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a circuit diagram showing an electrical equivalent circuit in the configuration shown in FIGS. 1 and 2;

FIG. 4 is a configuration diagram illustrating a circuit configuration example of a signal processing circuit.

5 is a waveform chart showing an example of a waveform of an AE signal obtained from a second amplifier of the signal processing circuit having the configuration shown in FIG. 4;

FIG. 6 is a front view showing another configuration example of the transmission coil of the acoustic emission detection device for a machine tool according to the embodiment of the first invention.

FIG. 7 is a configuration diagram including a partial vertical cross section showing a configuration example of an acoustic emission detection device for a machine tool according to an embodiment of the second invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Spindle 3 ... Dresser tool 4 ... Fixed part 5 ... Recess 6 ... Grindstone 11 ... Transmission coil 13 ... AE sensor 14 ... Receiving coil

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Chiaki Hirota 3-13-26 Yayumicho, Higashimatsuyama-shi, Saitama Prefecture Bosch Automotive System Higashimatsuyama Plant (72) Inventor Toshihisa Kanakubo 3 Yayumicho, Higashimatsuyama-shi, Saitama −13−26 Inside the Bosch Automotive System Higashimatsuyama Plant (72) Inventor Osamu Kubota 3-13-26 Inside the Bosch Automotive System Higashimatsuyama Plant, Higashimatsuyama City, Saitama Prefecture (72) Inventor Haruhiko Ueno Saitama (13) Inventor Yasuhiro Arimura 3-13-26 Yaumicho, Higashimatsuyama-shi, Higashimatsuyama-shi Term (reference) 3C029 DD16 3C034 CA14 CB12 CB14 DD14 3C047 AA06 AA10 AA15

Claims (4)

[Claims] A contact between the tool and the workpiece in a machine tool having a tool that is rotated and processing the workpiece by the tool is detected by an ultrasonic wave generated by the contact. Acoustic emission detection device for a machine tool, which is configured to be able to determine the transmission coil, wherein an ultrasonic sensor is provided on the tool or a rotating shaft for rotating the tool, and a transmission coil connected in series with the ultrasonic sensor. On the other hand, a receiving coil is provided at a fixed portion of the machine tool facing the transmitting coil, and a voltage induced in the receiving coil can be output to the outside.・ Emission detection device. 2. A dressing device configured to perform dressing of a grindstone for rotating a dresser tool, so that contact between the dresser tool and the grindstone can be determined by detecting ultrasonic waves generated by the contact. Acoustic machine tool
An emission detection device, wherein an ultrasonic sensor is provided on the dressing tool or a spindle for rotating the dressing tool,
While providing a transmission coil connected in series with the ultrasonic sensor, a fixed portion is fixed to a housing in which the spindle is housed, and a reception coil is provided on the fixed portion so as to face the transmission coil, and the reception coil is provided. An acoustic emission detection device for a machine tool, wherein an induced voltage can be output to the outside. 3. A dresser tool, wherein a dresser body formed in an annular shape is provided on an outer peripheral surface of a disk member formed in a disk shape, and a dresser tool is provided on a flat portion of the disk member opposed to a fixed portion. A concave portion is formed, and the transmitting coil and the ultrasonic sensor are housed in the concave portion. On the other hand, the fixed portion is formed in a bottomed cylindrical shape, and is fixed to the housing so that the opening side faces the dresser tool. The acoustic emission detecting device for a machine tool according to claim 2, wherein a receiving coil is housed inside the cylinder. 4. A dressing device configured to rotate a dresser tool and dress a grindstone so that a contact between the dresser tool and the grindstone can be determined by detecting an ultrasonic wave generated by the contact. An acoustic emission detection device for a machine tool, comprising: an ultrasonic sensor provided at a portion opposite to a plane portion of the dresser tool facing a housing in which a spindle for rotating the dresser tool is housed; While providing a transmission coil connected in series with the ultrasonic sensor, a reception coil is provided on a fixed member so as to face the transmission coil, and a voltage induced in the reception coil can be output to the outside. An acoustic emission detection device for a machine tool.