JPH02279258A - Detecting device for tool damage in machine tool - Google Patents

Abstract

PURPOSE:To almost eliminate the attenuation of an AE wave by fitting a sensor for detecting AE wave direct detecting the AE wave generated at the tool damaged time to a main shaft. CONSTITUTION:In either case of working a work W fitted to a main shaft 4 and driven by its rotation by a cutting tool 6 or working the work W by the cutting tool 6 fitted to the main shaft 4 and driven by rotation, AE wave generated at the time when the cutting tool 6 is damaged during cutting is transmitted to the sensor 17 for detecting the AE wave fitted to the main shaft 4 via the work W fitted to the main shaft 4 and the main shaft 4 or via the main shaft 4 only. This AE wave detected electric signal is transmitted in a noncontact state to the secondary side which is nonrotating member 15 side from the primary side which is a rotating main shaft side via the electromagnetic induction action, etc., of between the primary side and secondary side of a noncontact electric bonding means 19, the AE wave detected signal reproduced at the secondary side is processed in a detection signal processing circuit 26 and the automatic stoppage of the main shaft and the operation of an alarm are performed.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention aims to prevent damage to tools during machining operations in machine tools such as various lathes and drill presses by acoustic emission waves (hereinafter referred to as , AE wave).

(Prior art and its problems) When a cutting tool in a machine tool is damaged during machining,
Generally, ultrasonic waves called AE waves of 200 KHz or higher are generated, and a tool damage detection device is known that automatically detects damage to a tool by utilizing the generation of these AE waves.

However, in conventional tool damage detection devices of this kind, the sensor for detecting the AE wave peak was attached to the headstock that supports the spindle that rotates the tool or workpiece, so tool damage could occur at the bearing between the spindle and the headstock. The accompanying AE waves are significantly attenuated, and in order to perform highly accurate detection without malfunction, it is necessary to sufficiently improve the accuracy of the detection signal processing circuit, which has the disadvantage of increasing costs.

In addition, as described in the specification and drawings of Japanese Utility Model Application No. 62-78249, a liquid-filled chamber is formed around the main shaft, and the AE waves caused by damage to the tool are transmitted to the main shaft through the liquid filled in this liquid-filled chamber. It has been considered to transmit data from the AE wave crest output sensor on the stand side, but the formation of the above-mentioned liquid-integrated filling chamber and the filling of liquid into the liquid-filling chamber would inevitably result in a significant cost increase, making it impractical. Not.

(Means for solving the problem) In order to solve the conventional problems as mentioned above, the present invention
A sensor that detects acoustic emission waves when the tool is damaged is attached to the main shaft that rotates the workpiece or tool of the machine tool, and the sensor and the detection signal processing circuit are connected via non-contact electrical coupling means such as electromagnetic induction. , the primary side and the secondary side of the non-contact electrical coupling means are divided into the rear end of the main shaft and a non-rotating member opposing thereto, in a state of non-contact with each other and concentrically with the center of rotation of the main shaft. This paper proposes a tool damage detection device for a machine tool equipped with this tool.

(Function of the invention) In either case, when processing a workpiece that is attached to the main spindle and driven to rotate, using a cutting tool, or when processing a workpiece using a cutting tool that is attached to the main spindle and is rotationally driven, , the AE wave generated when the cutting tool is damaged during cutting is transmitted via the workpiece attached to the spindle and the spindle, or via only the spindle, The signal is transmitted to the AE wave detection sensor located at the sensor, and converted into an electrical signal in the sensor. This AE wave detection electric signal is transmitted from the primary side, which is the rotating main shaft side, to the non-rotating member side through electromagnetic induction between the primary side and the secondary side of the non-contact electrical coupling means. The AE wave detection signal transmitted to the secondary side in a non-contact state and reproduced on the secondary side is processed in the detection signal processing circuit, and necessary measures accompanying the AE wave detection, such as automatic stop of the spindle, etc. It is possible to activate the alarm.

(Example) An example of the present invention will be described below based on the attached illustrative drawings.

In FIG. 1, numeral 2 is a headstock in a turret lathe, which rotatably supports a main shaft 4 equipped with an automatic chuck 3 for gripping a workpiece 2 at its tip. Reference numeral 5 denotes a turret around which a plurality of tools are attached at equal intervals, and the figure shows only one cutting tool 6 for cutting the workpiece 2 attached to the turret 5, and the other tools are Not shown.

The main spindle 4 consists of a main spindle body 4a that is rotatably supported on the headstock 1, and a sleeve portion 4b that slides in the axial direction within the main spindle body 4a to open and close the automatic chuck 3, 7 is a hydraulic cylinder unit that opens and closes the automatic chuck 3 via the sleeve portion 4b. Said sleeve part 4b
The hydraulic cylinder unit 7 rotates together with the main shaft body 4a, and an AE wave detection unit 8 is attached to the rear end of the cylinder shaft portion 4b.

As shown in FIGS. 2 and 3, the AE wave detection unit 8 utilizes a male threaded portion 9 formed on the outer periphery of the rear end of the cylindrical shaft portion 4b of the main shaft 4 to detect the cylindrical shaft portion 4b. A base member 10 screw-fitted to the rear end, and a male threaded portion 12 formed on the outer periphery of the rear end small diameter cylindrical portion Il of the base member 10.
A cap-shaped member 13 is screw-fitted to the rear end of the base member IO by using a screw, and a bearing I4 is provided inside the cap-shaped member 13 to allow only relative rotation in a concentric state with the main shaft 4 (cylindrical shaft portion 4b). An AE wave detection sensor (piezoelectric element) is mounted on the bottom surface 11a of the small-diameter cylindrical portion 11 at the rear end of the base member 10 via a hard insulating plate 16 such as a ceramic plate. ) 17 is fixed, and a plastic material such as Duracon, which is fitted and fixed inside the small-diameter cylindrical portion 11 at the rear end of the base member 10 so as to cover the sensor 17, is attached to the seat 18 for induction as a non-contact electrical coupling means. A ferrite core 20b incorporating a primary coil 20a of the transformer 19 is connected to the main shaft 4 so that the primary coil 20a is connected to the main shaft 4.
(The tube-sleeve portion 4b) and the receiver is buried so as to be flush with the rear end surface of the seat 18. Further, at the front end of the non-rotating member 15, a ferrite core 21b having a built-in secondary coil 21a of the induction transformer I9 is arranged such that the secondary coil 21a is concentric with the main shaft 4 (cylindrical sleeve portion 4b) and It is buried so as to face the primary coil 20a with a small gap therebetween.

Reference numeral 22 denotes a rotation preventing means for the non-rotating member 15, and a rotation preventing ring 24 is fixed to the rear end of the non-rotating member 15 in an externally fitted state, and is fixed to the non-rotating member 15 by a screw 23; A rotation prevention rod 2 whose one end is screwed into the rotation prevention ring 24 and whose other end is fixed to the headstock 1 etc.
It consists of 5. Note that the fixing screw 23 can be omitted by fixing the rotation prevention ring 24 to the non-rotating member 15 at the tip of the rotation prevention rod 25.

As shown in FIG. 4, the primary coil 20a of the induction transformer 19 is connected to the AE wave peak output sensor 7, and the secondary coil 21a is connected to the band amplifier 27 constituting the detection signal processing circuit 26. has been done. The detection signal processing circuit 26 is basically a conventionally known circuit, and includes a detector 28 for detecting the output signal of the band amplifier 27, and a detector 28 for detecting whether the detected output signal is larger than a preset threshold value. The tool damage detection signal 30 is composed of a comparator 29 and the like that determines whether the The signal is input to the controller 31 that numerically controls the turret lathe, and the main spindle 4 is automatically stopped and an alarm is activated.

The workpiece 2 is gripped by the automatic chuck 3 at the tip of the main spindle 4,
A cutting tool 6 set on a turret 5 is used to rotate the workpiece 2 through the main shaft 4.
is cut, and by the rotation of the main shaft 4,
In the AE wave detection unit 8, the base member IO, the cap-shaped member 13, and the AE wave peak output sensor 1 are mounted on the seat 18.
, and the primary coil 20a of the induction transformer 19 is connected to the main shaft 4.
rotates as one. However, since the non-rotating member 15 inside the cap-shaped member 13 is fixed by the rotation preventing means 22, the secondary coil 21a of the induction coil 19 held by the non-rotating member 15 is not integrated with the main shaft 4. The primary coil 20 rotates integrally with the main shaft 4 without rotating.
It faces A with a small gap in between. Also, both coils 20
Since a and 21a are concentric with the main shaft 4, both coils 20
The relative positional relationship of a21a remains unchanged, so both coils 2
The electromagnetic induction effect between 0a and 21a is performed without any problem.

The cutting tool 6 cuts the workpiece 2 which is rotationally driven as described above.
If damage such as breakage occurs to the cutting tool 6 during machining, the generated AE waves will be transmitted from the workpiece 2 in contact with the tool 6 to the main shaft 4 (cylindrical sleeve portion 4b) and the AE wave detection unit 8. Base member IO1 and hard insulating plate I in
6, the AE wave is transmitted to the wave crest output sensor 1, and an electric signal corresponding to the AE wave is generated at the sensor 17.

This electric signal is transmitted to the primary coil 20 of the induction transformer 19.
Due to the non-contact electromagnetic induction between a and the secondary coil 21a, the electrical signal is transmitted to the circuit of the non-rotating secondary coil 21a, and the electric signal reproduced in the circuit of the secondary coil 21a is the detection signal. The processing circuit 26 processes the data in a conventional manner. That is, of the electric signal reproduced in the circuit of the secondary coil 21a, only a predetermined frequency band portion is amplified by the band amplifier 27 and detected by the wave detector 28. A comparator 29 compares whether this detection output signal is larger than a preset threshold, and if it is larger than the threshold, a tool damage detection signal 30 is output, and the controller 31 controls the spindle 4. Automatically stops and activates an alarm.

The AE wave detection unit 8 can also be attached to the rear end of the main shaft for rotating a tool in a machine tool such as a drilling machine, which rotates a tool. Further, although the induction transformer 19 that electrically couples in a non-contact manner by electromagnetic induction is used as the non-contact electrical coupling means, it is also possible to use non-contact electrical coupling means that utilizes electrostatic induction. Furthermore, AE for the main axis
The mounting of the sensor 1 for wave crest output depends on the position and the structure, or the mounting of the primary side of the non-contact electric coupling means to the rear end of the spindle depends on the structure, or the non-rotation that holds the secondary side of the non-contact electric coupling means. The support structure of the members, etc. are not limited to the above embodiments.

(Effects of the invention) As described above, according to the tool damage detection device according to the invention,
Direct detection of A and E waves generated when a tool is damaged, AE wave crest output sensor attached to the main shaft, 18...Plastic wheat making seat, 19...Induction transformer as non-contact electrical coupling means, 20a ...Primary coil, 21a
. . . Secondary coil, 22 .
Bandwidth amplifier, 28...Detector, 29...Comparator, 3
0... Tool damage detection signal, 31... Controller utility model registration applicant Daishowa Seiki Co., Ltd. No. 31 Figure 2 gE 4 Figure Procedure Nexi? Official document (method) August 21, 1989 1. Indication of the case 1999 Patent Application No. 89165 2. Name of the invention Tool damage detection device for machine tools 3. Person making the amendment Relationship to the case Application Personal Name 2 Daishowa Seiki Co., Ltd. 44 Agent 〒660 (1) "Name of the invention J" in the second line of page 1 of the specification is corrected to ``Name of the invention 1.

(2) "Scope of Claims for Utility Model Registration" on the 4th line of the same page
The text should be corrected to read "Claims."

(3) The phrase "detailed explanation of the invention" in line 14 of the same page is corrected to read "detailed explanation of the invention."

Above 6゜ Title of the invention subject to amendment, scope of claims, detailed description of the invention Procedures for amendment Written on August 21, 1989 (1) Indication of the incident Patent Application No. 89165, 1999 (2) Title of the invention Tool Damage Detection Device in Machine Tools 3゜ Person who makes the correction Relationship to the case Name of applicant - Daishowa Seiki Co., Ltd. 4, Agent 〒660 Full text of the specification 6. Full text of the details of the amendment as attached. correct.

Description 1. Title of the invention: Tool damage detection device in a machine tool 2. Claims: A sensor for detecting acoustic emission waves when a tool is damaged is attached to a main shaft that rotationally drives a workpiece or tool of a machine tool, The sensor and the detection signal processing circuit are connected through a non-contact electrical coupling means using electromagnetic induction, etc., and the primary side and the secondary side of the non-contact electrical coupling means are connected to the rear end of the main shaft and opposite thereto. A tool damage detection device for a machine tool, which is separately mounted on a non-rotating member in a non-contact state and concentrically with the rotation center of the main shaft.

3. Detailed Description of the Invention (Field of Industrial Application) The present invention aims to reduce damage to tools during machining operations in machine tools such as various lathes and drill presses by acoustic emission waves (hereinafter referred to as , AE wave).

(Prior art and its problems) When a cutting tool in a machine tool is damaged during machining,
Generally, ultrasonic waves called AE waves of 200 KHz or higher are generated, and a tool damage detection device is known that automatically detects damage to a tool by utilizing the generation of these AE waves.

However, in conventional tool damage detection devices of this kind, the sensor for detecting the AE wave peak was attached to the headstock that supports the spindle that rotates the tool or workpiece, so tool damage could occur at the bearing between the spindle and the headstock. The accompanying AE waves are greatly attenuated, and in order to perform highly accurate detection without malfunction, it is necessary to sufficiently improve the accuracy of the detection signal processing circuit, which has the disadvantage of increasing costs.

In addition, as described in the specification and drawings of Japanese Utility Model Application No. 62-78249, a liquid-filled chamber is formed around the main shaft, and the AE waves caused by damage to the tool are transmitted to the main shaft through the liquid filled in this liquid-filled chamber. It has been considered to transmit data from the AE wave peak output sensor on the stand side, but this is not practical as it would inevitably increase the cost significantly due to the formation of the liquid filling chamber and filling the liquid into the liquid filling chamber. .

(Means for Solving the Problems) In order to solve the conventional problems as described above, the present invention has the following features:
A sensor that detects acoustic emission waves when the tool is damaged is attached to the main shaft that rotates the workpiece or tool of the machine tool, and the sensor and the detection signal processing circuit are connected via non-contact electrical coupling means such as electromagnetic induction. , the primary side and the secondary side of the non-contact electrical coupling means are divided into the rear end of the main shaft and a non-rotating member opposing thereto, in a state of non-contact with each other and concentrically with the center of rotation of the main shaft. This paper proposes a tool damage detection device for a machine tool equipped with this tool.

(Operation of the invention) In either case, when processing a workpiece that is attached to the main shaft and driven to rotate with a cutting tool, or when processing a workpiece using a cutting tool that is attached to the main spindle and is rotationally driven. , the AE wave generated when the cutting tool is damaged during cutting is transmitted via the workpiece attached to the spindle and the spindle, or via only the spindle, The AE wave is transmitted to the wave crest output sensor and converted into an electrical signal at the sensor. This AE wave detection electric signal is transmitted from the primary side, which is the rotating main shaft side, to the non-rotating member side through electromagnetic induction between the primary side and the secondary side of the non-contact electrical coupling means. The AE wave detection signal transmitted to the secondary side in a non-contact state and reproduced on the secondary side is processed in the detection signal processing circuit, and necessary measures accompanying the AE wave detection, such as automatic stop of the spindle, etc. It is possible to activate the alarm.

(Example) An example of the present invention will be described below based on the attached illustrative drawings.

In FIG. 1, reference numeral 1 denotes a headstock in a turret lathe, which rotatably supports a main shaft 4 equipped with an automatic chuck 3 for gripping a workpiece 2 at its tip. Reference numeral 5 denotes a turret around which a plurality of tools are attached at equal intervals, and the figure shows only one cutting tool 6 for cutting the workpiece 2 attached to the turret 5, and the other tools are Not shown.

The main spindle 4 consists of a main spindle body 4a that is rotatably supported on a headstock l, and a cylindrical shaft portion 4b that slides in the axial direction within the main spindle body 4a to open and close the automatic chuck 3. , 7 is a hydraulic cylinder unit that opens and closes the automatic chuck 3 via the cylinder shaft portion 4b. The cylinder shaft portion 4b
The hydraulic cylinder unit 7 rotates together with the main shaft body 4a, and an AE wave detection unit 8 is attached to the rear end of the cylinder shaft portion 4b.

As shown in FIGS. 2 and 3, the AE wave detection unit 8 utilizes a male threaded portion 9 formed on the outer periphery of the rear end of the sleeve portion 4b of the main shaft 4 to detect the rear end of the sleeve portion 4b. A base member 10 screw-fitted at the end, and a male threaded portion 12 formed on the outer periphery of a small diameter cylindrical portion 11 at the rear end of the base member 10.
A cap-shaped member 13 is screw-fitted to the rear end of the base member 10 using a screw, and a bearing 14 is provided inside the cap-shaped member 13 to allow only relative rotation in a concentric state with the main shaft 4 (cylindrical shaft portion 4b). A sensor piezoelectric element for AE wave crest output is mounted on the bottom surface 11a of the small-diameter cylindrical portion 11 at the rear end of the base member 10 via a hard insulating plate 16 such as a ceramic plate. ) 17 is fixed, and a plastic material such as Duracon, which is fitted and fixed in the rear end small-diameter cylindrical portion 11 of the base member IO so as to cover this sensor 17, is attached to the seat 18 for induction as a non-contact electric coupling means. A ferrite core 20b incorporating a primary coil 20a of the transformer 19 is connected to the main shaft 4 so that the primary coil 20a is connected to the main shaft 4.
(Cylinder shaft portion 4b) and the receiver is buried so as to be flush with the rear end surface of the seat 18. Further, at the front end of the non-rotating member 15, a ferrite core 21b having a built-in secondary coil 21a of the induction transformer 19 is arranged such that the secondary coil 21a is concentric with the main shaft 4 (cylindrical sleeve portion 4b) and It is buried so as to face the primary coil 20a with a small gap therebetween.

Reference numeral 22 denotes a rotation preventing means for the non-rotating member 15, and the fixing screw 2 is fitted externally to the rear end of the non-rotating member 15.
3, a rotation stopper ring 24 is fixed to the non-rotating member 15 by a rotation stopper ring 24, and a rotation stopper rod 25 has one end screwed into the rotation stopper ring 24 and the other end fixed to the headstock 1 etc.
It is composed of. Note that the fixing screw 23 can be omitted by fixing the rotation prevention ring 24 to the non-rotating member 15 at the tip of the rotation prevention rod 25.

As shown in FIG. 4, the primary coil 20a of the induction transformer 19 is connected to the AE wave peak output sensor 7, and the secondary coil 21a is connected to the band amplifier 27 constituting the detection signal processing circuit 26. has been done. The detection signal processing circuit 26 is basically a conventionally known circuit, and includes a detector 28 for detecting the output signal of the band amplifier 27, and a detector 28 for detecting whether the detected output signal is larger than a preset threshold value. The tool damage detection signal 30 is composed of a comparator 29 and the like that determines whether the The signal is input to the controller 31 that numerically controls the turret lathe, and the main spindle 4 is automatically stopped and an alarm is activated.

The workpiece 2 is gripped by the automatic chuck 3 at the tip of the main spindle 4,
A cutting tool 6 set on a turret 5 is used to rotate the workpiece 2 through the main shaft 4.
is cut, and by the rotation of the main shaft 4,
In the AE wave detection unit 8, the base member 10, the cap-shaped member 13, and the AE wave crest output sensor 1 are mounted on the seat 18.
, and the primary coil 20a of the induction transformer 19 is connected to the main shaft 4.
rotates as one. However, since the non-rotating member 15 inside the cap-shaped member 13 is fixed by the rotation preventing means 22, the secondary coil 21a of the induction coil 19 held by the non-rotating member 15 is not integrated with the main shaft 4. The primary coil 20 rotates integrally with the main shaft 4 without rotating.
It faces A with a small gap in between. Also, both coils 20
a, 2] Since a is concentric with the main shaft 4, both coils 20
The relative positional relationship of a21a remains unchanged, so both coils 2
The electromagnetic induction effect between 0a and 21a is performed without any problem.

The cutting tool 6 cuts the workpiece 2 which is rotationally driven as described above.
If damage such as breakage occurs to the cutting tool 6 during machining, the generated AE waves will be transmitted from the workpiece 2 in contact with the tool 6 to the main shaft 4 (cylindrical sleeve portion 4b) and the AE wave detection unit 8. Base member 10 and hard insulating plate 1 in
6, the AE wave is transmitted to the wave crest output sensor 1, and an electric signal corresponding to the AE wave is generated at the sensor 17.

This electric signal is transmitted to the primary coil 20 of the induction transformer 19.
Due to the non-contact electromagnetic induction between a and the secondary coil 21a, the electrical signal is transmitted to the circuit of the non-rotating secondary coil 21a, and the electric signal reproduced in the circuit of the secondary coil 21a is the detection signal. The processing circuit 26 processes the data in a conventional manner. That is, of the electric signal reproduced in the circuit of the secondary coil 21a, only a predetermined frequency band portion is amplified by the band amplifier 27 and detected by the wave detector 28. A comparator 29 compares whether this detection output signal is larger than a preset threshold, and if it is larger than the threshold, a tool damage detection signal 30 is output, and the controller 31 controls the spindle 4. Automatically stops and activates an alarm.

The AE wave detection unit 8 can also be attached to the rear end of the main shaft for rotating a tool in a machine tool such as a drilling machine, which rotates a tool. Further, although the induction transformer 19 that electrically couples in a non-contact manner by electromagnetic induction is used as the non-contact electrical coupling means, it is also possible to use non-contact electrical coupling means that utilizes electrostatic induction. Furthermore, AE for the main axis
The mounting of the sensor 1 for wave crest output depends on the position and the structure, or the mounting of the primary side of the non-contact electric coupling means to the rear end of the spindle depends on the structure, or the non-rotation that holds the secondary side of the non-contact electric coupling means. The support structure of the members, etc. are not limited to the above embodiments.

(Effects of the Invention) As described above, according to the tool damage detection device according to the present invention,
Since the AE wave generated when the tool is damaged can be directly detected by the AE wave peak output sensor attached to the main shaft, the AE wave is much smaller than when a bearing is involved in the AE wave propagation system up to the sensor. There is almost no attenuation, and damage to the tool can be detected with high precision without malfunction even with a detection signal processing circuit with relatively low precision.

In addition, since only a non-contact electric coupling means such as an induction transformer is interposed between the rear end of the main shaft and the non-rotating member facing the main shaft, compared to the case where a liquid-filled chamber must be formed around the main shaft. Therefore, the structure is simple and can be implemented at low cost.

[Brief explanation of drawings]

Fig. 1 is a schematic plan view showing the main parts of a turret lathe equipped with an AE wave detection unit according to the present invention, Fig. 2 is an enlarged sectional view of the AE wave detection unit, and Fig. 3 is an exploded perspective view of the main parts. , FIG. 4 is a block diagram illustrating the configuration of the detection signal processing circuit. 4... Main spindle, 4a... Main spindle body, 4b... Cylindrical shaft portion, 6... Cutting tool, 8... AE wave detection unit, I
O... Pace member, 13... Cap-shaped member, 15
...Non-rotating member, 17...Sensor piezoelectric element for AE wave peak output), 18...Plastic malting seat, IO
...Induction transformer as non-contact electrical coupling means, 20
a...Primary side coil, 21a...Secondary side coil, 2
2... Stopping means for the non-rotating member 15, 24... Stopping ring, 25... Stopping rod, 26...
Detection signal processing circuit, 27... Bandwidth amplifier, 28...
Detector, 29...Comparator, 30...Tool damage detection signal, 31...Controller patent applicant Daishowa Seiki Co., Ltd.

Claims (1)

[Claims] A sensor that detects acoustic emission waves when the tool is damaged is attached to the main shaft that rotates the workpiece or tool of the machine tool, and the sensor and the detection signal processing circuit are connected via non-contact electrical coupling means such as electromagnetic induction. , the primary side and the secondary side of the non-contact electrical coupling means are divided into the rear end of the main shaft and a non-rotating member opposing thereto, in a state of non-contact with each other and concentrically with the center of rotation of the main shaft. A tool damage detection device in a machine tool equipped with the tool.