JP2003334743A - Tool state detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool state detecting device for surely detecting the state of a tool even in process of machining, and even when a load is small. <P>SOLUTION: A tool side electrode 17 is installed via an insulator 16 in a tool part 15 having the tool 12 rotatably driven in a state of being installed at the tip of a spindle 3. A diode 18 is connected between the tool side electrode 17 and the tool part 15. A high frequency signal is outputted between the tool side electrode 17 and a workpiece 54 by a high frequency signal output device 20. The breakage of the tool 12 is detected on the basis of the state of a high frequency signal when the tool 12 is displaced to a position for contacting with the workpiece 54. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool state detection device for detecting the state of a tool that is rotationally driven while being attached to the tip of a spindle.

[0002]

A machine tool such as a so-called machining center for processing a work piece is often operated unmanned. Therefore, for example, when a tool used for machining is broken, it is necessary to automatically detect the state and replace the tool.

Conventionally, there are various methods for detecting breakage as a tool state. For example, after processing is completed,
When the tool is stored in the tool magazine, a machine detection type that uses a swing bar type limit switch to detect it, or a spindle (spindle) with no load due to breakage of the tool causes power consumption to change. There is a power detection type that is detected based on.

However, in the machine detection type, the detection is performed after all the processing steps are completed. Therefore, if the tool is broken during the processing, the workpiece may be processed in that state. There is. In that case, the broken state of the tool may be deteriorated, or the processing failure of the workpiece may occur.

In the power detection type, when the load on the spindle during machining is small and the power consumption is small,
Since the amount of change in power when the tool breaks is small, detection cannot be performed. For example, when a φ2 drill hole is drilled with a spindle rated at 22 kW, there is no difference in power change due to tool breakage.

The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to reliably detect the state of a tool even during machining and when the load is small. It is to provide a detection device.

[0007]

In order to achieve the above object, a tool state detecting device according to a first aspect of the present invention is a tool portion including a tool which is rotationally driven in a state of being attached to a tip portion of a spindle. , A tool-side electrode that is mounted via an insulator, a fixed-side electrode that is disposed so as to be electrostatically coupled to the tool-side electrode with a predetermined gap, and one end of the output terminal is the fixed-side electrode. Of the high-frequency signal output means for outputting a high-frequency signal between the output terminals, which are connected to each other, and the other end of which is connected to the workpiece side made of a conductive material to be processed by the tool, A rectifying element connected between them is provided, and the state of the tool is detected based on the displacement state of the tool and the state of the high frequency signal output by the high frequency signal output means.

That is, when the high frequency signal output from the high frequency signal output means is supplied from the fixed side electrode to the tool side electrode by electrostatic coupling, the high frequency signal is rectified into a DC signal by the rectifying element and applied to the tool portion. When the rotation of the main shaft is stopped, the main shaft and the head (housing) supporting the main shaft are in conductive contact with each other via bearings, so that the resistance of the DC signal, that is, the tool (part). → Spindle →
The DC resistance in the path of bearing → head → column (supporting pillar) → bed (base) → table → workpiece is close to 0Ω.

On the other hand, when the main shaft rotates, the ball or roller of the bearing is covered with an oil film, so that the oil film forms a capacitance and the resistance of the DC signal becomes extremely large. When and are in contact with each other, that part is short-circuited.

As described above, the impedance of the measurement system changes depending on whether or not the tool and the workpiece are in contact with each other. Therefore, under the influence of the change, the high frequency signal output means outputs a high frequency signal. The state changes. Therefore, the state of the tool can be detected by referring to the change of the high frequency signal accompanying the displacement of the tool. The state can be detected even while the workpiece is being processed by the tool, and even when the load applied to the tool is small.

Further, since the fixed side electrode and the tool side electrode are electrostatically coupled to each other, a high frequency signal can be supplied to the tool side in a non-contact state, so that the tool side is worn as it rotates. It is possible to supply in a stable state without any member that does.

In this case, as described in claim 2, it is preferable to detect breakage of the tool as the state of the tool. That is, if the workpiece is machined in a state where the tool is broken, a machining defect is likely to occur, and therefore, according to the present invention, the breakage of the tool can be quickly detected and dealt with.

Further, as described in claim 3, it is preferable that an impedance adjusting means for adjusting the impedance of the transmission line of the high frequency signal is arranged on the fixed electrode side. That is, if the impedance of the transmission line is adjusted to achieve matching, the high-frequency signal can be transmitted to the tool side without reflection, so that the change state can be easily observed.

In this case, as described in claim 4, the state of the tool may be detected by measuring the voltage standing wave ratio on the high frequency signal output means side. That is, if the impedance of the measurement system in a state where the tool and the workpiece are in contact with each other is matched in advance, for example, when the state of the tool changes and the workpiece is no longer in contact with the workpiece, The impedance deviates from the matched state and a reflected wave is generated. Therefore, if the occurrence of the reflected wave is detected by measuring the voltage standing wave ratio, the state of the tool can be easily detected.

Further, as described in claim 5, it is preferable that the rectifying element is arranged in a state of being embedded in the inside of the insulator. According to this structure, the rectifying element is connected to the tool side electrode and the tool portion. Can be easily connected between. In addition, it is possible to prevent the rectifying element from falling off due to vibration or the like when machining is performed by rotating the main shaft.

In addition, as described in claim 6, it is preferable to provide a compressed air delivery means for delivering compressed air between the fixed side electrode and the tool side electrode. That is, since the fixed side electrode and the tool side electrode are arranged with a predetermined interval so as to be electrostatically coupled, a short circuit occurs if a coolant liquid or cutting waste generated by machining enters the gap between them. There is a possibility that the impedance of the measurement system may change and the state detection may not be performed accurately. Therefore,
By sending compressed air between the electrodes by the compressed air sending means, it is possible to prevent cutting chips from entering.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows the structure of a machine tool and also shows the structure of a tool state detection device of the present invention. The spindle device 1 of the machine tool 50 is, for example, a built-in type in which a spindle (spindle) 3 and an induction motor 4 that rotationally drives the spindle 3 are built in a hollow cylindrical head (housing) 2. . The tip portion and the intermediate portion of the spindle 3 are rotatably supported on the head 2 by ball bearings 5 and 6. The head 2 and the spindle 3 are both made of iron-based material.

A rotor 7 composed of a core and a squirrel-cage winding (end ring) is arranged on the spindle 3 side of a portion located approximately in the middle of the portions supported by the ball bearings 5 and 6, and the head 2 of the head 2 is disposed. The induction motor 4 is configured by disposing a stator 8 composed of a core and a winding (coil end) facing the core with a predetermined gap in the inner peripheral portion.

Inside the spindle 3, there are provided a drawbar 9, which is a known mechanism, a chuck mechanism arranged on the tip side of the drawbar 9, a drawbar spring (not shown), and the like. On the other hand, the cutting tool 12 is attached to a tool holder 13, and the tool holder 13 has a pull stud 14 at its upper end. Then, the draw bar 9 on the spindle 3 side is axially displaced by a drive mechanism (not shown), so that the spindle 3
Inside, the chuck mechanism grips the pull stud 14 of the tool holder 13 via a steel ball, so that the tool 12 is attached to the tip portion of the spindle 3.
The tool 12 and the tool holder 13 form a tool unit 15.

The machine tool 50 has a saddle 5 on a bed 51.
2 and the table 53 are arranged, and the workpiece 54 made of a conductive material is placed on the table 53. A column 55 is erected on the bed 51,
The column 55 supports the spindle device 1.

There is a drive mechanism (not shown) between the column 55 and the spindle device 1, and the spindle device 1 is displaced in the vertical direction so that the workpiece 12 can be machined by the tool 12. Has become. The bed 51, saddle 52, table 53, and column 55 are also made of iron-based material.

By the way, the saddle 52 on the bed 51 and the table 53 are electrically non-contact with each other through the oil film, but their contact area is relatively large, and the table Since the moving speed of 53 with respect to the saddle 52 is small, the DC resistance value is small (it depends on the equipment, but it is about 1 kΩ or less).

FIG. 2A shows an enlarged view of the tool section 15. A ring-shaped tool-side electrode 17 is arranged on the outer peripheral portion of the tool holder 13 with a ring-shaped insulator 16 interposed therebetween. Then, inside the insulator 16, the anode is connected to the tool-side electrode 17 and the cathode is connected to the tool holder 1.
A diode (rectifying element) 18 connected to 3 is embedded. Incidentally, in FIG. 1, the diode 18 is shown outside for easy understanding.

On the outside of the tool-side electrode 17, fixed-side electrodes 19 having an arc shape are arranged with a predetermined interval. The fixed electrode 19 is fixedly supported by the head 2, for example. In addition, in FIG.
The positional relationship between the two electrodes 17 and 19 is shown in a sectional view.

One end of the output terminal of the high-frequency signal output device (high-frequency signal output means) 20 has an SWR (Standing Wafer).
ve Ratio) is connected to the fixed side electrode 19 via a meter 21, and the other end is a table 53 (machine side ground) of the spindle device 1.
It is connected to the. The high frequency signal output device 20 outputs a high frequency signal of 100 MHz, for example. That is, 100M
A high frequency signal of Hz can be transmitted even by a capacitance of about 2 or 3 pF by electrostatic coupling, and since it is not used even in the FM band, it has little noise.

On the fixed electrode 19 side, an impedance adjusting section (impedance adjusting means) 22 for adjusting the impedance of the line of the measurement system is provided. That is, as shown by an equivalent circuit in FIG. 3, one end of the output terminal of the high-frequency signal output device 20 is connected to the fixed-side electrode 19 via the coil 23 and the trimmer capacitor 24, and between both output terminals. A trimmer capacitor 25 is also connected. The coil 23 and the capacitors 24 and 25 constitute the impedance adjusting section 22. The impedance adjusting unit 22 may be partially or wholly attached to the fixed-side electrode 19 to be integrally configured, or may be arranged between the output terminal of the high-frequency signal output device 20 and the fixed-side electrode 19. May be.

Compressed air delivery device (compressed air delivery means) 2
6 is for delivering dry compressed air from the fixed side electrode 19 side to between the two electrodes 17, 19. That is, the tool 12
When the workpiece 54 is processed by the above, cutting chips are generated, or a coolant liquid for cooling is supplied by a supply means (not shown). If they enter between the electrodes 17 and 19, there is a possibility that they will short-circuit, so dry compressed air is sent out to prevent this.

That is, as shown in FIG.
Is attached to the fixed side electrode portion 27 made of resin, for example. The fixed electrode portion 27 is formed in an arc shape having a thickness in the radial direction, and a groove 28 having a depth of, for example, about 1 mm is formed on the surface side facing the tool side electrode 17.
The fixed electrode 19 is attached to the groove 28.

A through hole 29 is provided on the left side of the fixed electrode section 27 in FIG. 4 (b), and the compressed air sent from the compressed air sending device 26 passes through this through hole 29. And is supplied between the tool-side electrode 17 and the fixed-side electrode 19. The clearance between the tool-side electrode 17 and the fixed-side electrode portion 27 is, for example, about 0.5 mm. Also, the groove 28
The through hole 29 also constitutes a compressed air delivery means.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 5 (a) shows the configuration of the measurement system centering on the electrical connection relationship, and FIG. 5 (b) shows its equivalent circuit. The capacitor C1 is a capacitive component of electrostatic coupling between the fixed-side electrode 19 and the tool-side electrode 17, and has a resistance R on the cathode side of the diode 18.
1 is a resistance component of the tool unit 15. The switch SW corresponds to a contact / non-contact state between the tool 12 and the workpiece 54.

The resistance R2 is the resistance of the ball bearings 5 and 6 when the rotation of the spindle 3 is stopped, and the capacitor C2 is equivalent to the resistance of the spindle 3 when the spindle 3 is rotating. This is the capacity between the head 2 and the head 2.

That is, the DC resistance when the rotation of the spindle 3 is stopped is a value close to 0Ω, but the spindle 3
When is rotated, the balls of the bearings in the ball bearings 5 and 6 are covered with the oil film, and the oil film forms the capacitance C2. The DC resistance in this case is, for example, about 20 k to 30 kΩ, although it depends on the equipment. The resistance R3 is a resistance component included in the head 2, the bed 51, the saddle 52, the table 53, the column 55, and the like. still,
A high frequency choke coil (smoothing means) 30 is inserted on the cathode side of the diode 18, and the choke coil 30 is provided for the purpose of smoothing the signal rectified by the diode 18.

In FIG. 5 (b), the switch SW is open with the tool 12 and the workpiece 54 in a non-contact state,
In addition, when the rotation of the spindle 3 is stopped, the high frequency signal output by the high frequency signal output device 20 flows through the path indicated by the solid line of the capacitor C1, the diode 18, the resistors R2 and R3, and when the spindle 3 rotates, The resistor R2 in the above path replaces the capacitor C2.

Then, from that state, the tool 12 and the workpiece 54 come into contact with each other, and when the switch SW is closed, the high-frequency signal is transferred to the capacitor C1, the diode 18, and the like.
It flows in the path shown by the broken line of the resistor R1 and the switch SW. Therefore, in this state, the impedance adjustment unit 22 performs adjustment in advance so that the line impedance of the measurement system matches.

That is, if the tool 12 is sound, the tip of the tool 12 contacts the workpiece 54 when the spindle 1 is lowered to a predetermined position, and the two are electrically connected to each other.
Will be closed. On the other hand, if the tool 12 breaks,
Even if the spindle 1 is lowered to a predetermined position, the tip of the tool 12 does not come into contact with the workpiece 54, so the two are not electrically connected. Therefore, since the switch SW remains open, the impedances of the transmission lines are not matched and the reflection occurs. Then, the reflected wave causes a standing wave to be generated in the transmission line, and the state thereof can be observed by the SWR meter 21.

Considering the actual usage, the work piece 5
When the spindle device 1 is pulled up after the processing of 4 is completed,
The breakage may be detected depending on whether or not there is contact when the tip of the tool 12 reaches the predetermined position.

As described above, according to this embodiment, the tool 1 that is rotationally driven while being mounted on the tip of the spindle 3 is used.
The tool side electrode 17 is attached to the tool part 15 having 2 through the insulator 16, the diode 18 is connected between the tool side electrode 17 and the tool part 15, and the tool side electrode 17 and the workpiece are processed. The high-frequency signal output device 20 outputs a high-frequency signal to the object 54. Then, the breakage of the tool 12 is detected based on the state of the high-frequency signal when the tool 12 is displaced to the position where it contacts the workpiece 54.

That is, when the tool 12 is broken, even if the tool 12 is displaced to the position where it contacts the workpiece, the two do not contact each other and the impedance of the measurement system changes.
Under the influence of the change, the output state of the high frequency signal changes. Therefore, the breakage of the tool 12 can be detected based on the change state at that time. The breakage can be quickly detected even while the workpiece 54 is being processed, and the breakage can be detected even when the load applied to the tool 12 is small.

Since the fixed side electrode 19 is provided so as to be electrostatically coupled to the tool side electrode 17 with a predetermined gap, a high frequency signal is supplied to the tool 12 side in a non-contact state. Therefore, there is no member that wears as the tool 12 rotates, and the supply can be performed in a stable state.

Further, since the impedance adjusting unit 22 for adjusting the impedance of the transmission line of the high frequency signal is arranged on the fixed electrode 19 side, the impedance of the transmission line is matched so that the high frequency signal is not reflected. Since it can be transmitted to the tool 12 side, the change state can be easily observed. And the SWR meter 2
1, the breakage of the tool 12 can be easily detected by measuring the voltage standing wave ratio on the high frequency signal output device 20 side.

Furthermore, since the diode 18 is arranged so as to be embedded inside the insulator 16, the diode 18 can be easily connected between the tool-side electrode 17 and the tool portion 15. In addition, it is possible to prevent the diode 18 from falling off due to vibration when the spindle 3 is rotated for processing.

In addition, the fixed side electrode 19 and the tool side electrode 17
Compressed air delivery device 2 for delivering compressed air between
Since 3 is provided, it is possible to prevent a short circuit from occurring due to the coolant liquid or cutting chips generated by processing entering the gap between the two.

The present invention is not limited to the embodiments described above and shown in the drawings, but the following modifications and expansions are possible. The cathode of the diode 18 may be directly connected to the tool 12. The rectifying element does not necessarily have to be embedded inside the insulator if the rectifying element is securely fixed and there is no risk of falling off. The breakage does not necessarily have to be detected by detecting the voltage standing wave ratio, but may be detected by, for example, observing a change in voltage amplitude, a change in transmission power amount, or the like. If there is no risk that coolant, cutting dust, or the like will enter between the fixed-side electrode 19 and the tool-side electrode 17 due to other measures, the compressed air delivery device 23 may not be provided. Not limited to the built-in type spindle device, the motor may be arranged outside the spindle device.

The state of the tool is not limited to the one that detects breakage, but it is also possible to detect the length and width of the tool, or the deflection of the tool, for example, as follows. The length of the tool can be detected by the amount of displacement of the spindle device at the time when its tip comes into contact with the workpiece, and the width of the tool can be similarly detected when the tool is displaced in the width direction. In addition, if the conductor plate electrically connected to the workpiece is placed at a position corresponding to the allowable range of the runout width, the runout width of the tool will be reduced by the tool contacting the conductor plate. It can be detected that the allowable range is full.
Further, it may be applied to measure the state of the workpiece, for example, the dimension after processing. That is, this can also be detected by the amount of displacement of the spindle device when the tool contacts the workpiece.

[0045]

The present invention is as described above, and has the following effects. According to the tool state detection device of claim 1, the tool-side electrode is attached via an insulator to a tool portion including a tool that is rotationally driven in a state of being attached to a tip end portion of a spindle. A high frequency signal is output between the fixed side electrode disposed so as to be electrostatically coupled to the side electrode and the workpiece side, and based on the displacement state of the tool and the state of the high frequency signal output by the high frequency signal output means. To detect the tool condition.

That is, since the impedance of the measurement system changes depending on whether the tool and the workpiece are in contact with each other,
The output state of the high frequency signal changes on the side of the high frequency signal output means under the influence of the change, so that the state of the tool can be detected. Then, it can be detected even while the workpiece is being processed or even when the load applied to the tool is small. Further, since the high-frequency signal can be supplied to the tool side in a non-contact state, it is possible to supply the high-frequency signal in a stable state without any member that wears as the tool side rotates.

According to the tool state detecting device of the second aspect, since the breakage of the tool is detected as the state of the tool, the breakage can be quickly detected and dealt with. Claim 3
According to the tool state detecting device described above, the impedance adjusting means for adjusting the impedance of the transmission line of the high frequency signal is arranged on the fixed electrode side, so that the impedance of the transmission line should be adjusted to achieve matching. For example, the high frequency signal can be transmitted to the tool side in a state where reflection does not occur, and the change state can be easily observed.

According to the tool state detecting device of the fourth aspect, since the state of the tool is detected by measuring the voltage standing wave ratio on the high frequency signal output means side, the transmission line is changed when the state of the tool changes. The tool state can be easily detected by detecting that the reflected wave is generated when the impedance of the is out of the matched state.

According to the tool state detecting device of the fifth aspect, since the rectifying element is arranged so as to be embedded in the insulator, the rectifying element is easily connected between the tool side electrode and the tool portion. be able to. In addition, it is possible to prevent the rectifying element from falling off due to vibration or the like when machining is performed by rotating the main shaft.

According to the tool state detecting device of the sixth aspect, since the compressed air delivery means for delivering the compressed air is provided between the fixed side electrode and the tool side electrode, the coolant liquid or the machining is provided in the gap between the two. It is possible to prevent the occurrence of a short circuit due to the inclusion of cutting chips and the like generated by.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a machine tool and a configuration of a tool state detection device, which is an embodiment of the present invention.

FIG. 2A is an enlarged view of a tool portion, and FIG. 2B is a cross-sectional view showing a positional relationship between two electrodes.

FIG. 3 is an equivalent circuit diagram showing a configuration of an impedance adjusting unit.

FIG. 4A is a perspective view showing a configuration of a fixed-side electrode portion,
FIG. 3B is a plan view showing the same portion as seen through.

5A is a diagram showing the configuration of a measurement system, focusing on electrical connection relationships, and FIG. 5B is an equivalent circuit diagram thereof.

[Explanation of symbols]

3 is a spindle (spindle), 12 is a tool, 15 is a tool part,
Reference numeral 16 is an insulator, 17 is a tool side electrode, 18 is a diode (rectifying element), 19 is a fixed side electrode, 20 is a high frequency signal output device (high frequency signal output means), 21 is a SWR meter,
22 is an impedance adjusting unit (impedance adjusting means), 27 is a compressed air delivery device (compressed air delivery means),
Reference numeral 28 is a groove (compressed air delivery means), 29 is a through hole (compressed air delivery means), and 54 is a workpiece.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinobu Shimizu             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Kenichi Sato             Aichi Prefecture, Nagoya City Chikusa-ku, Shinjukucho 3-2 (72) Inventor Hajime Mizutani             26 Hirako Yoshiwara-cho, Toyota-shi, Aichi Fuji Seiko             Within the corporation F-term (reference) 3C029 DD04

Claims (6)

[Claims] 1. A tool-side electrode mounted via an insulator on a tool part having a tool that is rotationally driven in the state of being mounted on the tip of a spindle, and a predetermined distance from this tool-side electrode. A fixed-side electrode disposed so as to be electrostatically coupled to the fixed-side electrode, one end of the output terminal is connected to the fixed-side electrode, and the other end is connected to the workpiece side made of a conductive material processed by the tool. A high-frequency signal output unit that is connected and outputs a high-frequency signal between output terminals; and a rectifying element that is connected between the tool-side electrode and the tool unit, the displacement state of the tool, and the high-frequency signal output A tool state detection device for detecting the state of the tool based on the state of the high frequency signal output by the means. 2. The tool state detection device according to claim 1, wherein breakage of the tool is detected as the state of the tool. 3. The tool state detecting device according to claim 2, wherein impedance adjusting means for adjusting the impedance of the transmission line of the high frequency signal is arranged on the fixed electrode side. 4. The tool state detection device according to claim 3, wherein the state of the tool is detected by measuring a voltage standing wave ratio on the high frequency signal output means side. 5. The tool state detection device according to claim 1, wherein the rectifying element is arranged in a state of being embedded inside the insulator. 6. The tool according to claim 1, further comprising compressed air delivery means for delivering compressed air between the fixed side electrode and the tool side electrode. State detection device.