JP4831984B2 - Non-contact wear detection system for rotary cutting blade, wear detection method for throw-away tip, and milling tool - Google Patents

Description

  The present invention relates to a non-contact wear detection system for a rotary cutting blade, a wear detection method for a throw-away tip, and a milling tool, and in particular, during cutting (in-process) without stopping the rotation of the rotary cutting blade. The present invention relates to a contact-type non-contact type wear detection system for a rotary cutting blade that can detect wear of the rotary cutting blade, a wear detection method for a throw-away tip, and a milling tool.

  Rotating cutting blades with throwaway inserts attached to the cutting part are used in various machining processes. However, wear of this throwaway insert is a direct cause of defects in processed products, so it is early and reliable. A detection system is needed. However, it is not easy to examine how much the edge of the throw-away tip during wear is worn. In particular, it is very difficult in the working environment to detect the wear amount of the cutting edge ridge without interrupting the cutting process during the cutting process.

  As conventional methods for detecting the amount of wear on the cutting edge, (1) cutting is interrupted, the throw-away tip is removed from the holder, etc., and the cutting edge is observed with a tool microscope, etc. (2) cutting edge Phenomena that accompany wear, such as a decrease in cutting force, an increase in vibration, and the generation of abnormal noise, are detected by a sensor installed in the vicinity of the machined part on the machine tool, and the cutting edge ridge is determined based on the detection signal. There was a way to estimate the amount of wear.

  However, the above method (1) has to be performed by interrupting the cutting process, and further, there is a problem that the amount of wear of the cutting edge cannot be quantitatively detected and the accuracy is not good. Further, the method (2) has a problem that a complicated detection device is required, and that the wear amount detection sensitivity is poor and the reliability is insufficient.

In order to solve such a problem, a sensor portion of a conductive film extending along the above-mentioned cutting edge ridge is provided in the vicinity of the cutting edge ridge of the throw-away tip, specifically, the flank of the throw-away tip, and this sensor When both ends of the part are connected to an external detection circuit, the electrical resistance value of the sensor part is measured, and when the cutting edge is worn and the sensor part is disconnected, the cutting edge is worn out from the change in resistance value There is disclosed a throw-away tip with a wear sensor that makes it possible to know the above. (For example, see Patent Document 1)
In the case of detecting the wear state of the cutting edge ridge using the throwaway tip with a wear sensor as disclosed in Patent Document 1, it is assumed that the sensor portion of the throwaway tip is connected to an external detection circuit. It becomes. For this reason, the throw-away tip with a wear sensor is applied to a tool (for example, a lathe) in which the work material is rotated and the work material is cut without rotating the tool itself.

  However, for example, in the case of a milling tool in which the tool itself rotates, the throw-away tip is held at the tip of the milling cutter and rotates at a high speed, so the sensor unit provided on the throw-away tip is electrically connected to an external detection circuit. I can't connect. For this reason, with conventional milling tools, in order to detect the wear state, the cutting process is usually interrupted, the throw-away tip is removed from the milling cutter, and the degree of wear on the cutting edge and the presence or absence of defects are observed with a tool microscope or the like. However, there is a problem that the efficiency of the cutting work is reduced and complicated, and the accuracy is low because the amount of wear cannot be detected quantitatively.

As a method for solving such a problem, when the tool itself rotates like a milling tool, the sensor unit provided near the cutting edge ridge of the throw-away tip cannot be connected to an external detection circuit. There is known a non-contact type wear detection system that can detect wear of a wear member such as a throw-away tip in a non-contact manner using a switch as a non-contact type detection means. (For example, see Patent Document 2)
In the above-mentioned Patent Document 2, a sensor unit 200 (for example, a sensor line) made of a conductive film provided on a worn part as shown in FIG. A resonance circuit 100 formed of a tuning capacitor 300 and a high-frequency coil 400 is formed. The high frequency coil 400 of the resonance circuit 100 is disposed in the proximity of the oscillation coil 600 in the high frequency oscillation type proximity switch 500. The oscillation coil 600 is connected to the oscillation circuit 700, and the output of the oscillation circuit 700 is detected by the detection circuit 800. With this configuration, when the sensor unit 200 is in a normal state with no wear, a high-frequency current flows through the resonance circuit 100, and oscillation of the oscillation circuit 700 is reduced or stopped. On the other hand, when the sensor unit 200 is worn and disconnected, the high frequency current does not flow through the resonance circuit 100 and the oscillation circuit 700 oscillates. Thereby, the wear of the worn part is detected in a non-contact manner.
JP 2001-121308 A JP 2004-74393 A

  However, in the thing of the said patent document 2, the detection accuracy which distinguishes and detects the state which is in the position which the oscillation coil 600 and the high frequency coil 400 of the high frequency oscillation type proximity switch 500 are in the position which opposes is not enough. Therefore, there is a defect that cannot be detected when the rotary cutting blade to which the throw-away tip is attached is rotating at a high speed. Actually, the rotational speed of the rotary cutting blade can be practically used only up to about 500 rpm, and when the rotary cutting blade rotates at 1000 rpm or more, it does not face the state where the oscillation coil 600 and the high frequency coil 400 face each other. It was not possible to detect the state in a completely different manner.

  The present invention has been made in view of such a point, and an object of the present invention is to be able to accurately and easily detect wear of a worn portion of a rotary cutting blade in a non-contact manner and at high speed rotation. Another object of the present invention is to provide a non-contact wear detection system for a rotary cutting blade, a wear detection method for a throw-away tip, and a milling tool.

  In order to achieve the above object, the present inventors have conducted extensive experimental studies. As a result, for example, a conductive sensor portion made of a conductive film is provided on a cutting edge portion (a worn portion) of a throw-away tip or the like. A conductive coil is provided on a rotating body to which a chip is attached, and the conductive sensor unit and the conductive coil are connected in series to form a conductive circuit. The conductive coil is periodically close to the conductive coil by the rotation of the rotating body. When the high-frequency oscillation coil is disposed in a non-contact position, when the conductive coil is close to the high-frequency oscillation coil, the conductive circuit is in a conductive state or in a non-conductive state. It has been found that the self-inductance changes slightly, and in the present invention, focusing on this point, the difference in self-inductance of such a high-frequency oscillation coil is effectively generated. And it was set to provide a resonant circuit can be detected.

Specifically, the invention of claim 1 includes an RC circuit in which a capacitor and a resistor are connected in parallel, a high-frequency oscillation coil, a resonance circuit in which a high-frequency oscillation source is connected in series, and a worn part of the rotary cutting blade. And a conductive circuit in which a conductive coil provided on a rotating body to which the rotary cutting blade is attached is connected in series, and the high-frequency oscillation coil of the resonance circuit is configured to rotate the rotating circuit. It is arranged in close contact with the outside of the body in a non-contact manner, and by the rotation of the rotating body, the high-frequency oscillation coil of the resonance circuit and the conductive coil of the conductive circuit are periodically positioned so as to face each other and not to face each other. is arranged to vary the oscillation frequency range of the resonant circuit, 308～311KHz or is set in a range of 356～370KHz,, further a detecting unit detecting an output of said RC circuit It is obtain configuration.

  According to a second aspect of the present invention, in the non-contact type wear detection system for the rotary cutting blade according to the first aspect, the conductive circuit is provided with a tuning capacitor connected in series with the conductive sensor unit and the conductive coil. It is the composition which is.

  According to a third aspect of the present invention, in the non-contact wear detection system for the rotary cutting blade according to the first or second aspect, the detection unit is configured to detect a voltage value or a current value of the RC circuit. It is.

The invention of claim 4 is an invention of a method for detecting wear of a throwaway tip, wherein a conductive sensor portion made of a conductive film is provided in the vicinity of the cutting edge portion of the throwaway tip attached to the rotary cutting blade. Are connected in series with a conductive coil to form a conductive circuit, and the conductive circuit is attached to a rotating body including the rotary cutting blade and rotates together with a throw-away tip, and the conductive coil is rotated by rotation of the rotating body. A non-contact type high-frequency oscillation coil is disposed close to the outside of the rotation path , and the high-frequency oscillation coil is periodically moved to a position where the conductive coil of the conductive circuit is opposed to the position where the high-frequency oscillation coil is not opposed to the rotation circuit. It is arranged to vary, the high-frequency oscillation coil, a high frequency oscillation source, and distributing the resonant circuit capacitor and a resistor are connected to an RC circuit connected in parallel to the series And, close oscillation frequency region of the resonance circuit, 308～311KHz, or is set in a range of 340～370KHz, the conductive coil is the high-frequency oscillation coil in each of the time and non-conductive when conduction of the conductive circuit When the self-inductance of the high-frequency oscillation coil is detected and the conductive sensor portion is disconnected due to wear of the cutting edge portion of the throw-away tip, and the conductive circuit becomes non-conductive, the high-frequency oscillation coil The wear is detected based on the amount of change of the self-inductance with respect to the conduction time.

  According to a fifth aspect of the present invention, in the method for detecting wear of a throw-away tip according to the fourth aspect, a difference occurs depending on a change in self-inductance of the high-frequency oscillation coil of the resonance circuit between when the conductive circuit is conductive and when the conductive circuit is conductive. By detecting the voltage value or current value of the RC circuit, the amount of change in the self-inductance is detected.

Invention of Claim 6 is invention of a milling tool, Comprising: The milling cutter by which the throwaway tip which provided the conductive sensor part which consists of an electroconductive film in the cutting-blade part vicinity was mounted | worn with the front-end | tip part, and this milling cutter is attached And a drive key for positioning the milling arbor with respect to the rotation axis of the milling tool, and a conductive coil is installed in the milling arbor at a position spaced circumferentially from the drive key. And the conductive sensor unit are connected in series to form a conductive circuit , and a high-frequency oscillation coil is disposed in a non-contact manner outside the rotation path of the conductive coil, and the high-frequency oscillation coil is connected to the milling arbor. arranged by the rotation so that periodically changes in the position not located facing opposite to each other with the conductive coil, wherein Frequency oscillation coil, a high frequency oscillation source, and RC circuit with a resistor and a capacitor connected in parallel to form a resonant circuit connected in series, transmission frequency region of the resonance circuit, 308～311KHz or 340~370kHz of The detection unit is set to a range and includes a detection unit that detects a voltage value or a current value of the RC circuit of the resonance circuit.

  A seventh aspect of the present invention is the milling tool according to the sixth aspect, wherein the conductive circuit is provided with a tuning capacitor connected in series with the conductive sensor section and the conductive coil.

  According to the first aspect of the present invention, when the conductive coil is close to the high frequency oscillation coil, the conductive sensor portion is disconnected due to the conductive circuit being in a conductive state and the worn portion being worn, and the conductive circuit is in a non-conductive state. When this happens, the self-inductance of the high-frequency oscillation coil changes, and as a result, the output (voltage value or current value) of the RC circuit also changes. It becomes possible to detect wear of a worn part in a non-contact manner. Further, even when the rotating body rotates at high speed, it is possible to reliably detect the wear of the worn part. Therefore, even if the rotating body is rotating at high speed, it is possible to detect the wear of the damaged part with a reliable and simple configuration, and even when the rotation is stopped, the output of the RC circuit at the time of rotation immediately before the stop By detecting this, wear can be detected.

  According to the second aspect of the present invention, the disconnection of the conductive sensor portion provided at the worn part of the rotary cutting blade (that is, the worn part) is more clearly and reliably detected at both the high speed rotation and the low speed rotation of the rotating body. Can be detected.

  According to invention of Claim 3, the structure of a detection part becomes simple and the cost reduction of a detection part can be achieved.

  According to the invention of claim 4, as in the invention of claim 1, even if the rotating body rotates at a high speed, the wear of the cutting edge portion of the throw-away tip can be detected with a reliable and simple configuration. .

  According to the invention of claim 5, the self-inductance of the high-frequency oscillation coil can be detected by a simple method, and the disconnection of the conductive sensor part (that is, the wear of the cutting edge part) can be detected clearly and reliably. it can.

  According to the invention of claim 6, as in the invention of claim 1, the wear of the cutting edge portion of the throw-away tip in the milling tool can be detected with a simple configuration during the rotation of the milling tool rotating shaft.

  According to the seventh aspect of the present invention, it is possible to more accurately detect the wear of the cutting edge portion of the throw-away tip in the milling tool.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing a milling tool including a non-contact type wear detection system according to an embodiment of the present invention. As shown in FIG. 2, this milling tool has a milling cutter 31 (rotary cutting blade) having a plurality of throw-away tips 30 attached to the tip portion at predetermined intervals in the circumferential direction as shown in FIG. 3. The taper portion 32a of the milling arbor 32 is attached to a spindle 33 (milling tool rotating shaft) that rotates with respect to the milling machine body 37. At the time of cutting, the milling cutter 31 rotates at high speed about the axis A of the spindle 33 together with the milling arbor 32. Thus, the milling arbor 32 constitutes a rotating body.

  In the milling arbor 32, a columnar portion 34 protruding in the radial direction from the tapered portion 32 a is integrally formed near the base of the tapered portion 32 a. A coil embedded portion 36 is provided on the outer peripheral portion of the cylindrical portion 34. The coil burying portion 36 is obtained by embedding a ferrite core 21 a around which the conductive coil 21 is wound into a hole from the outside and integrating it with the milling arbor 32. A notch groove 38 for balancing the rotation is provided at a position symmetrical to the coil embedding portion 36 with respect to the central axis of the milling arbor 32 (axial center A of the spindle 33) on the outer peripheral portion of the cylindrical portion 34. Yes.

The spindle 33 has two drive keys 39 for positioning against and spindle 33 transmitted to the milling arbor 32 the rotational force of the spindle 33 is provided at mutually symmetrical positions with respect to the axis A of the spindle 33 ing. Then, as shown in FIG. 2, the recesses 35 into which the drive keys 39 are fitted are respectively located at substantially central positions (two places) between the coil embedding part 36 and the notch groove 38 on the outer peripheral part of the cylindrical part 34. Provided (only one recess 35 is visible in FIG. 2). The conductive coil 21, the cutout groove 38, and the drive key 39 (recess 35) are located at substantially the same distance from the central axis of the milling arbor 32 at the outer peripheral portion of the cylindrical portion 34.

  The conductive coil 21 is disposed such that its core 21a extends in the radial direction of the milling arbor 32 (that is, one end surface of the core 21a faces the radial outer side of the milling arbor 32). The conductive circuit 20 is formed together with the conductive sensor portion 23 of the chip 30 and the tuning capacitor 22.

  In the vicinity of the rotation path of the conductive coil 21 due to the rotation of the milling arbor 32, the high-frequency oscillation coil 12 is disposed. The high-frequency oscillation coil 12 is attached to the milling machine body 37 such that one end surface of the ferrite core 12 a faces the outer peripheral surface of the cylindrical portion 34 of the milling arbor 32, and the conductive coil 21 is rotated by the rotation of the milling arbor 32. Are disposed at positions that are periodically close to each other (for example, a position having an interval of 0.5 mm to 3 mm). That is, every time the milling arbor 32 makes one rotation, the outer end surface of the core 21a of the conductive coil 21 and the end surface on the milling arbor side of the core 12a of the high-frequency oscillation coil 12 face each other in a state of being close to each other.

  An example of the throw-away tip 30 is shown in FIG. The throw-away tip 30 has a base material 40 having a trapezoidal cross section. The upper surface of the base material 40 is a rake surface 40a, and the side surface is a flank 40b. A ridge line part between the rake face 40a and the flank face 40b is a cutting edge ridge 41 (cutting edge part) for performing cutting, and the cutting edge ridge 41 or its vicinity corresponds to a worn part.

A screw insertion hole 42 penetrating from the upper surface to the lower surface is formed at the center of the base material 40. When the throw-away tip 30 is mounted in a tip pocket such as a holder, a clamp screw is inserted into the screw insertion hole 42 and screwed into a screw hole formed in the tip pocket to fix the throw-away tip 30. In the state where the throw-away tip 30 is fixed, for example, the corner portion 43 is used for cutting. The tip 30 shown in this embodiment can use another corner portion 43 for cutting by loosening the clamp screw and rotating it 90 °. Therefore, the four corner portions 43 can sequentially cut by rotating by 90 °.

  Conductive sensor portions 23 each made of a conductive film extending along the cutting edge ridge 41 are formed on the flank 40 b in the vicinity of the four corner portions 43 (near the cutting edge ridge 41). That is, the conductive sensor portion 23 extends along the cutting edge ridge 41 across two adjacent flank faces 40 b and 40 b forming the corner portion 43. The conductive sensor unit 23 is formed in an electrically insulated state with respect to the base material 40.

  As shown in FIG. 5, the distance W from the cutting edge ridge 41 to the lower side of the conductive sensor portion 23 matches the life reference amount of the corner portion 43 (the wear limit of the flank 40 b). The life reference amount of the corner portion 43 in the throw-away tip 30 used for a milling tool or the like is usually within a range of 0.05 to 0.7 mm from the cutting edge ridge 41. Accordingly, the width t of the conductive sensor unit 23 is set to a value equal to or smaller than the distance W from the cutting edge 41 to the lower side of the conductive sensor unit 23 (that is, t ≦ W). Note that the life reference amount and the wear limit are not constant, and may vary depending on the cutting purpose such as preliminary cutting (rough cutting), standard cutting, and finishing cutting.

  Preferably, as shown in FIG. 6, the conductive sensor portion 23 ′ is formed across the rake face 40 a and the relief surface 40 b via the cutting edge ridge 41, and the upper side of the conductive sensor section 23 ′ is from the cutting edge ridge 41. It is preferable to be formed on the rake face 40a side. This is because, as will be described later, it is necessary to irradiate the cutting edge ridge 41 with a laser when forming a pattern of the conductive sensor portion 23 by removing an unnecessary conductive film by laser processing or the like. This is to prevent the ridge 41 from being once melted and re-solidified into a rough surface state.

  When cutting is performed at the corner 43, wear of the cutting edge ridge 41 or the flank 40b in the vicinity thereof progresses with time. As the wear of the flank 40b progresses and reaches the conductive sensor portion 23, and further wear progresses, the life reference amount is finally reached and the conductive sensor portion 23 is disconnected.

  As shown in FIG. 4, one end of the conductive sensor unit 23 is connected to the contact region 25 via the connection line 24. In addition, the other end of the conductive sensor unit 23 is connected to the contact region 29 via the folded part 26, the folded line 27, and the connection line 28. The two contact areas 25 and 29 are arranged in a pair and are electrically connected to an external circuit of the chip 30. The connection lines 24 and 28, the folded portion 26, the folded line 27, and the contact areas 25 and 29 are formed of a conductive film integrally with the conductive sensor portion 23 and are in an insulated state with respect to the base material 40. Further, the connection lines 24 and 28, the folded portion 26 and the folded line 27 are sufficiently larger than the width t of the conductive sensor portion 23 so as not to affect the detection of the change in the resistance value of the conductive sensor portion 23. Have a large width. The two contact regions 25 and 29 also have a sufficiently large area so as not to interfere with the connection with the external circuit. In addition, it is preferable that the space | interval (D shown in FIG. 5) of the conductive sensor part 23 and the folding | turning line 27 is 0.05 mm or more.

As the base material 40 of the throw-away tip 30, for example, an alumina sintered body, a silicon nitride sintered body, a cermet, a cemented carbide, a cubic boron nitride sintered body (cBN), a diamond sintered body (PCD), etc. can be used. It is. Further, the conductive film such as the conductive sensor unit 23 is composed of a periodic table 4a, 5a, 6a group metal such as Ti, Zr, V, Nb, Ta, Cr, Mo, W, or an iron group metal such as Co, Ni, Fe, or the like. Metal materials such as Al, and periodic tables 4a, 5a, such as TiC, VC, NbC, TaC, Cr3C2, Mo2C, WC, W2C, TiN, VN, NbN, TaN, CrN, TiCN, NbCN, TaCN, CrCN, etc. It is formed of carbide, nitride, carbonitride, (Ti, Al) N, or the like of a 6a group metal. Of these, it is particularly preferable to use TiN.

  In order to manufacture the conductive sensor portion 23, first, a conductive film is formed on the surface of the chip relief surface 40b by a CVD method, a PVD method such as ion plating, sputtering, or vapor deposition, or a plating method. Next, the conductive film is processed into a predetermined pattern including the connection lines 24 and 28, the return part 26, the return line 27, and the contact areas 25 and 29 in addition to the conductive sensor part 23 by laser processing, etching, or the like. The thickness of the conductive film such as the conductive sensor unit 23 is about 0.05 to 20 μm, preferably 0.1 to 5 μm.

  When the base material 40 of the throw-away chip 30 is formed of an insulator such as an alumina sintered body, a silicon nitride sintered body, or cBN, the conductive sensor unit 23 and the like are directly formed on the surface thereof. When the base material is formed of a conductive material such as cermet or cemented carbide, an intermediate layer made of an insulator such as alumina is interposed. The intermediate layer made of an insulator such as alumina has an effect of electrically separating the conductive sensor unit 23. Such an intermediate layer is formed between the surface of the base material 40 and the conductive sensor portion 23 or the like (conductive film) by employing a method such as a CVD method. The intermediate layer may have a thickness of about 1 to 10 μm.

  FIG. 7 is a schematic explanatory view showing a state in which the above throwaway tip 30 is mounted on the milling cutter 31. A plurality of (usually, 2 to 20) chip mounting pockets 51 are provided at predetermined intervals on the periphery of the lower surface of the milling cutter 31, and the throw-away chip 30 is mounted in each pocket 51. That is, the clamp screw 44 is inserted into the screw insertion hole 42 provided in the throw-away tip 30 and screwed into the screw hole provided in the side surface of the pocket 51 to fix the throw-away tip 30 in a predetermined position. The throw-away tip 30 is not limited to being fixed with the clamp screw 44, and may be fixed by, for example, screwing a clamper.

  As shown in FIG. 8, an area 50 in which a pair of probes 52 and 53 protrudes is formed on one side surface of the pocket 51 facing the pair of contact areas 25 and 29 provided on the seating surface of the throw-away tip 30. Is provided. The probes 52 and 53 are elastically biased by a spring or the like, and the tips protrude from the surface of the region 50. For this reason, when the chip 30 is mounted, the probes 52 and 53 are pushed down, and the tips of the probes 52 and 53 come into contact with the pair of contact regions 25 and 29 to be in an electrically contact state. In the throw-away tip 30 shown in FIG. 4, the pair of contact areas 25 and 29 are formed on the seating surface opposite to the rake face 40a, but this is formed on the side surface in the pocket 51 as shown in FIG. This is because the probes 52 and 53 are brought into contact with each other. Therefore, at least one of the pair of contact areas 25 and 29 can be formed on the other surface, for example, the flank 40b, according to the installation positions of the probes 52 and 53.

  As shown in FIGS. 7 and 8, one end of two lead wires 54 is connected to the probes 52 and 53, respectively. The other ends of the two lead wires 54 are respectively connected to the conductive coil 21 and the tuning capacitor 22 to form a conductive circuit 20 described later.

In FIG. 1, in order to explain the resonance circuit 10 and the conductive circuit 20 in an easy-to-understand manner, they are simply described in the structure of the milling tool. As shown in FIG. 9, the resonance circuit 10 includes an RC circuit 11 in which a capacitor 11a and a resistor 11b are connected in parallel, a high-frequency oscillation coil 12, and a high-frequency oscillation source 13 (AC power supply) for high-frequency oscillation. It is connected. In this embodiment, the resonance circuit 10 performs oscillation and detection simultaneously. As described above, the high-frequency oscillation coil 12 is positioned close to the outer peripheral surface of the cylindrical portion 34 of the milling arbor 32, and the conductive coil 21 wound around the core 21 a is disposed on the outer peripheral portion of the cylindrical portion 34. ing. The conductive coil 21, the tuning capacitor 22, and the conductive sensor unit 23 are connected in series to form a closed circuit, thereby forming the conductive circuit 20.

  The relationship between the voltages applied to each element in the resonance circuit 10, that is, the high-frequency oscillation coil 12, the capacitor 11a, and the resistor 11b is shown in the following equations (1) and (2). In equations (1) and (2), L is the inductance (unit: H) of the high-frequency oscillation coil 12, C is the capacitance (unit: F) of the capacitor 11a, and R is the resistance value (unit) of the resistor 11b. : Ω), Em is the amplitude of the AC power supply voltage, ω is the angular frequency of the AC power supply voltage (unit: rad / s), θ is the phase difference (unit: rad) due to circuit components, and t is the time (unit: s). ).

  The voltage VL (unit: V) across the high-frequency oscillation coil 12 is

となる。

It becomes.

  The voltage Vr (unit: V) across the resistor 11b and the voltage Vc (unit: V) across the capacitor 11a are:

となる。

It becomes.

  The resonance frequency f (unit: Hz) is expressed by the following equation (3). That is,

となる。

It becomes.

  The resonance circuit 10 has a large output compared to a resonance circuit composed of an LC series circuit or an LC parallel circuit, so that the resonance circuit 10 is used in a noisy machine tool or a factory where a plurality of machine tools are installed. However, accurate detection can be performed. In particular, since the resonance circuit is made to resonate, detection is easy from the viewpoint of noise countermeasures. Further, in order to detect a small change in inductance as described later, it is required that the change amount of the output voltage or current is larger than the change amount of the inductance near the resonance point. Usually, the inductance is smaller than 1H and mH. Or, considering that it is on the order of μH, in order to capture a small inductance change, it is preferable to include a low-order L term. In that respect, the voltage VL across the high-frequency oscillation coil 12, the voltage Vr across the resistor 11b, and the voltage Vc across the capacitor 11a shown in the equations (1) and (2) 12 is represented by a linear function of the inductance L, which is excellent in capturing a small change in inductance, and is an RC circuit 11 in which a capacitor 11a and a resistor 11b are arranged in parallel.

  A detection unit 14 for detecting a voltage (Vr or Vc) as an output of the RC circuit 11 is connected to both ends of the RC circuit 11 of the resonance circuit 10. The detection unit 14 has a configuration as shown in FIG. 10, for example. That is, the voltage waveform detection unit 15 of the detection unit 14 detects the voltage waveform across the RC circuit 11, rectifies the result by the rectification unit 16, and sends the output value to the comparison unit 18. The comparison unit 18 compares the threshold set by the threshold setting unit 17 with the output value from the rectification unit 16. By setting this threshold value to a value obtained when the conductive sensor unit 23 of the conductive circuit 20 is disconnected due to wear, when the output value exceeds the threshold value, the conductive sensor unit 23 of the conductive circuit 20 The notification unit 19 notifies that the disconnection has occurred due to wear. Examples of such notification forms include generally known notifications such as voice notification and lighting display.

  In the present embodiment, the voltage waveform detection unit 15 detects the voltage (Vr or Vc) between both ends of the RC circuit 11, but does not detect the voltage value but corresponds to the voltage. For example, the current value of the RC circuit 11 may be detected.

  Further, as another configuration of the detection unit 14, a change amount of the voltage value or current value of the RC circuit 11 corresponding to an inductance change amount between when the conductive sensor unit 23 is disconnected and when it is not disconnected is detected, and the change amount is detected. When the value is larger than the predetermined threshold value, the notification unit 19 may notify that the conductive sensor unit 23 is disconnected due to wear.

  Next, the operation state of the milling cutter 31 shown in FIG. 1 will be described in detail. Due to the rotation of the milling arbor 32, the coil arbor side end surface of the core 12 of the high-frequency oscillation coil 12 has a coil-embedded portion 36 (conductive coil 21) on the outer peripheral surface of the cylindrical portion 34, a notch groove 38, a drive key 39, and The other parts (hereinafter referred to as arbor main bodies) face each other periodically. The self-inductance for the high-frequency oscillation signal from the high-frequency oscillation coil 12 is detected as a result of being different depending on the facing portion. In particular, when the conductive sensor portion 23 of the conductive circuit 20 is disconnected and the conductive circuit 20 becomes non-conductive, when the conductive coil 21 faces the high-frequency oscillation coil 12, the high-frequency oscillation coil 12 has a core 21a of the conductive coil 21. A self-inductance corresponding to is detected.

  Thus, the inductance of the high-frequency oscillation coil 12 changes according to the portion of the outer peripheral surface of the cylindrical portion 34 facing the high-frequency oscillation coil 12, and the frequency characteristics of the resonance circuit 10 in each case change.

  Specifically, in order to determine the oscillation frequency of the resonance circuit 10, the RC of the resonance circuit 10 when the conductive coil 21, the arbor body (made of metal), and the drive key 39 face the high-frequency oscillation coil 12. The frequency characteristic of the output voltage of the circuit 11 was examined. When the conductive coil 21 was opposed, both when the conductive sensor unit 23 was disconnected (when the conductive circuit 20 was not conductive) and when it was not disconnected (when the conductive circuit 20 was conductive) were examined. Then, the output voltage between both ends of the resistor 11b (R = 50 kΩ) in the RC circuit 11 was measured by variously changing the capacitance of the capacitor 11a in the RC circuit 11 and the oscillation frequency in the resonance circuit 10.

  FIG. 11 and FIG. 12 show frequency characteristics when the capacitance C of the capacitor 11a of the RC circuit 11 is set to 440 pF. In FIG. 11 showing the frequency characteristics near the resonance point, when the conductive sensor portion 23 is disconnected, the frequency curve when the conductive coil 21 faces the high frequency oscillation coil 12 is X1, and when the conductive sensor portion 23 is not disconnected. The frequency curve when the conductive coil 21 faces the high-frequency oscillation coil 12 is X2, the frequency curve when the arbor body faces the high-frequency oscillation coil 12, X3, and the frequency curve when the drive key 39 faces the high-frequency oscillation coil 12 Are indicated by X4. In either case, the resonance frequency exists between 307 and 317 kHz, and it can be seen that the inductance change of the high-frequency oscillation coil 12 is extremely small. Moreover, the kurtosis of the curve changes reflecting the Q value in each case, and the order of the magnitude of the output voltage differs for each frequency region. Since the output voltage at the time of disconnection of the conductive sensor unit 23 is the highest at 308 to 311 kHz, if the oscillation frequency of the resonance circuit 10 is set within this range, a signal can be output to the notification unit 19 only at the time of disconnection. However, since the frequency width is as small as 3 kHz, there is a concern about malfunction due to the influence of noise or the like.

  FIG. 12 shows frequency characteristics at 340 to 370 kHz, which is larger than the frequency range shown in FIG. In the frequency range of 356 kHz or more, the output voltage at the time of disconnection of the conductive sensor unit 23 is the smallest, and it is understood that the disconnection of the conductive sensor unit 23 can be identified in a wider frequency range than the above-described 308 to 311 kHz. .

  Therefore, the output signal waveform of the RC circuit 11 when the oscillation frequency was 363 kHz and the milling arbor 32 was rotating was measured. FIG. 13 shows an example of the output signal waveform when the rotational speed of the milling arbor 32 is 600 rpm. In this test, the same milling arbor 32 as in FIGS. 1 and 2 was used. However, the conductive coil 21 was embedded in the outer peripheral portion of the cylindrical portion 34 of the milling arbor 32 in a state where two pieces connected in series were close to each other (coil interval 25 mm). In the outer peripheral portion of the cylindrical portion 34, at a position symmetrical to the conductive coil 21 with respect to the central axis of the milling arbor 32 (axial center A of the spindle 33), a length of 30 mm in the circumferential direction is provided to balance the movement of the milling arbor 32. A notch groove 38 is provided. A recess 35 for a drive key 39 is provided at approximately the center position (two locations) between the conductive coil 21 and the notch groove 38 on the outer periphery of the cylindrical portion 34, and the drive key 39 is fitted into the recess 35. ing. Under the influence of the respective portions of the cylindrical portion 34, the waveform shown in FIG. 13 increases or decreases in a complicated manner, but the output voltage when the conductive sensor portion 23 is disconnected (see the broken line) and the output voltage when not disconnected There is a clear difference (see solid line). For example, by setting the output voltage threshold to 0.43 V, it is possible to construct a system that outputs a signal to the notification unit 19 only at the time of disconnection.

  Further, the output voltage between both ends of the resistor 11b of the RC circuit 11 in the resonance circuit 10 is changed by changing the rotational speed and the oscillation frequency of the milling arbor 32 by using only one conductive coil 21 of the milling arbor 32 used in the test. Was measured. In addition, the drive key 39 used the concave shape and the convex shape simultaneously.

  The measurement results are shown in FIGS. 14 to 17, an output voltage waveform when the conductive sensor unit 23 is not disconnected is indicated by T (see the solid line), and an output voltage waveform when the conductive sensor unit 23 is disconnected is indicated by D (see the broken line). The output voltage when the conductive coil 21 faces the high-frequency oscillation coil 12 is such that the concave and convex drive keys 39 and the notch groove 38 face the high-frequency oscillation coil 12 when the conductive sensor portion 23 is not disconnected. The voltage level is the same as that at the time, but when the wire is disconnected, the output voltage is significantly different from the others. This difference in output voltage is the same regardless of whether the rotational speed is 300 rpm, 2000 rpm, or 6000 rpm, and it was possible to clearly distinguish between the time of disconnection and the time of no disconnection, and to detect this. 14 to 17, the arbor metal portion refers to a metal portion of the arbor body.

  In this way, the oscillation frequency is a predetermined value that can clearly distinguish the output voltage of the RC circuit 11 when the conductive coil 21 is in close proximity to the high-frequency oscillation coil 12 between when the conductive sensor unit 23 is disconnected and when it is not disconnected. In the above example, the frequency is set to 308 to 311 kHz, or a frequency of 356 kHz or higher), and when the conductive circuit 20 is conductive (when the conductive sensor unit 23 is not disconnected) and non-conductive (when the conductive sensor unit 23 is disconnected). If the self-inductance of the high-frequency oscillation coil 12 (that is, the output voltage of the RC circuit 11) when the conductive coil 21 is in close proximity to the high-frequency oscillation coil 12 is detected, the conductive sensor unit 23 is disconnected. The amount of change of the self-inductance of the high-frequency oscillation coil 12 when the conductive circuit 20 becomes non-conductive (ie, the RC circuit) The amount of change) in the first output voltage, it is possible to detect the wear of the cutting edge 41 of the throw-away tip 30.

  Therefore, in the present embodiment, by detecting the output voltage of the RC circuit 11 of the resonant circuit 10, the state of the entire circumference of the cylindrical portion 34 of the milling arbor 32 can be detected with respect to the rotation of the milling arbor 32, and It is possible to detect clearly and accurately when the conductive sensor unit 23 is disconnected and when the conductive sensor unit 23 is not disconnected. Accordingly, during the rotation of the milling arbor 32, the disconnection of the conductive sensor unit 23, that is, the milling cutter 31. The wear of the cutting edge 41 of the throw-away tip 30 can be detected in a non-contact manner. Further, even when the milling arbor 32 is rotating at a high speed of 6000 rpm, the wear of the cutting edge ridge 41 can be easily detected. In addition, even when the rotation is stopped, wear can be detected by detecting the output of the RC circuit 11 at the time of rotation immediately before the stop.

  In the above-described embodiment, the conductive circuit 20 is provided with the tuning capacitor 22 connected in series with the conductive sensor unit 23 and the conductive coil 21. However, the conductive circuit 20 eliminates the tuning capacitor 22, and the conductive sensor The part 23 and the conductive coil 21 may be connected in series to form a closed circuit. When a test was performed with such a circuit without the tuning capacitor 22, it was possible to detect the distinction between disconnection and non-disconnection, as in FIGS. 14 to 17.

  In the above embodiment, the conductive coil 21 is embedded in the cylindrical portion 34 of the milling arbor 32. Instead, a flange is attached to the outer periphery of the milling arbor 32 with a bolt or the like, and the conductive coil is attached to the flange. Anyway. In this case, the flange is preferably made of a metal or a magnetic material, but a nonmagnetic material may be used as long as it does not adversely affect the detection of wear.

  Furthermore, in the said embodiment, only one coil embedding part 36 (conductive coil 21) is provided with respect to several throwaway chips 30, and the conductive sensor part 32 of all the throwaway chips 30 and one conductive coil are provided. All the parts 21 are connected in series to form one conductive circuit 20. In this case, the conductive sensor portion 32 of any one of the throwaway tips 30 is disconnected, and the throwaway tip 30 disconnected from the conductive sensor portion 32 is replaced with a new one (or is replaced with a new cutting edge 41). The result is different from the worn state of the cutting edge ridge 41 of the other throw-away tip 30. When the wear state of the cutting edge ridge 41 of all the throwaway tips 30 is desired to be the same, it is preferable to replace the entire throwaway tip 30 with a new one (or switch to the new cutting edge 41). In this way, since it is not necessary to distinguish and detect which of the throwaway chips 30 the conductive sensor portion 32 is disconnected, such a distinction is not made in the embodiment. However, even if all the throwaway tips 30 are replaced, if it is desired to distinguish and detect which one of the throwaway tips 30 is worn out, the conductive sensor unit 23 in any one throwaway tip 30 is detected. What is necessary is just to make it possible to detect this disconnection separately from others. The distinction method is simple and will not be described here.

  A plurality of conductive coils 21 may be provided on the outer peripheral portion of the cylindrical portion 34 of the milling arbor 32 with a predetermined interval in the circumferential direction. For example, simply, the notch groove 38 of the above embodiment may be used as a new coil embedded portion 36, and the conductive coil 21 may be embedded in the new coil embedded portion 36. Then, a plurality of throwaway chips 30 may be grouped and connected for each conductive coil 21. As a result, a plurality of throw-away tips 30 attached to the milling cutter 31 are grouped, and a plurality of conductive circuits 20 are configured separately in each group, so that the throw-away tip 30 belonging to which group is worn out May be determined.

  In this way, when the number of the conductive coils 21 (coil embedding part 36) is plural, the number may be two or more, and even if the number is the same as the throw-away tip 30, It may be a number that can be grouped as follows. Thereby, it can be determined that the plurality of throwaway tips 30 are worn out, for example, two adjacent throwaway tips 30 are worn out.

  In addition, in the above embodiment, the non-contact type wear detection system of the present invention is applied to a milling tool. However, the non-contact type wear detection system of the present invention is not limited to application to a milling tool, and rotates. The present invention can be applied to other tools in the same manner, and can also be applied to detect wear of a worn portion of the rotary cutting blade in various apparatuses including a rotating cutting blade.

  The non-contact type wear detection system of the present invention is useful for a machine equipped with a rotary cutting blade having a worn part that is worn by use, such as a milling tool.

It is a front view which shows the milling tool provided with the non-contact-type wear detection system which concerns on embodiment of this invention. It is a perspective view of the milling arbor attached to the main axis | shaft of the milling tool shown in FIG. It is a perspective view of the milling cutter attached to the milling arbor shown in FIG. It is a perspective view which shows an example of a throw away tip. It is the elements on larger scale which expand and show the conductive sensor part of the throw away tip shown in FIG. It is a partial expansion perspective view which shows the other structure of the conductive sensor part of a throw away chip. It is a schematic explanatory drawing which shows the mounting method to the milling cutter of a throw away tip. It is a partial expansion perspective view of the pocket for chip | tip mounting | wearing of a milling cutter. It is a circuit diagram which shows a high frequency oscillation circuit. It is a block diagram which shows an example of the detection part of FIG. It is a frequency characteristic figure of RC circuit output of a resonance circuit when each of a conductive coil, an arbor body, and a drive key opposes a high frequency oscillation coil. FIG. 12 is a diagram corresponding to FIG. 11 illustrating frequency characteristics in a frequency region different from FIG. 11. It is a figure which shows the output signal waveform of RC circuit of a resonance circuit when a milling arbor is rotating in the case where there are two conductive coils. It is a figure which shows the output signal waveform of RC circuit of a resonance circuit when a milling arbor is rotating in the case where there is one conductive coil. FIG. 15 is a diagram corresponding to FIG. 14 when the transmission frequency is changed. FIG. 15 is a diagram corresponding to FIG. 14 when the rotation speed of the milling arbor is changed with respect to FIG. FIG. 15 is a view corresponding to FIG. 14 when the rotation speed of the milling arbor is further changed with respect to FIG. 14. It is a circuit block diagram which shows the conventional non-contact-type wear detection system.

DESCRIPTION OF SYMBOLS 10 Resonant circuit 11 RC circuit 11a Capacitor 11b Resistance 12 High frequency oscillation coil 13 High frequency oscillation source 14 Detection part 20 Conductive circuit 21 Conductive coil 22 Tuning capacitor 23 Conductive sensor part 30 Throw away tip 31 Milling cutter (rotary cutting blade)
32 Milling arbor (rotating body)
33 Spindle (Rotating axis of milling tool)
38 Notch 39 Drive Key 41 Cutting Edge (Cutting Edge) (Worn Part)

Claims (7)

An RC circuit in which a capacitor and a resistor are connected in parallel, a high-frequency oscillation coil, and a resonance circuit in which a high-frequency oscillation source is connected in series;
A conductive sensor part comprising a conductive film provided on a worn part of the rotary cutting blade and a conductive circuit provided in series with a conductive coil provided on a rotary body to which the rotary cutting blade is attached;
The high-frequency oscillation coil of the resonance circuit is disposed in a non-contact proximity to the outside of the rotating body, and the rotation of the rotating body causes the high-frequency oscillation coil of the resonance circuit and the conductive coil of the conductive circuit to face each other. It is arranged so that it periodically changes to a position that does not oppose and
The oscillation frequency region of the resonance circuit is set to a range of 308 to 311 kHz, or 356 to 370 kHz,
A non-contact type wear detection system for a rotary cutting blade, further comprising a detection unit for detecting an output of the RC circuit. In the non-contact type wear detection system of the rotary cutting blade according to claim 1,
A non-contact type wear detection system for a rotary cutting blade, wherein the conductive circuit is provided with a tuning capacitor connected in series with the conductive sensor unit and the conductive coil. In the non-contact type wear detection system of the rotary cutting blade according to claim 1 or 2,
The said detection part is comprised so that the voltage value or current value of the said RC circuit may be detected, The non-contact-type wear detection system of the rotary cutting blade characterized by the above-mentioned. A conductive sensor portion made of a conductive film is provided near the cutting edge portion of the throw-away tip attached to the rotary cutting blade, and this conductive sensor portion is connected in series with a conductive coil to form a conductive circuit. Attached to a rotating body including the rotary cutting blade and rotated with a throw-away tip,
A high-frequency oscillation coil is arranged close to the outside of the rotation path of the conductive coil by the rotation of the rotating body , and the high-frequency oscillation coil faces the conductive coil of the conductive circuit by the rotation of the rotating body. It is arranged to change periodically to a position that does not face the position,
A high-frequency oscillation coil, a high-frequency oscillation source, and a resonance circuit in which an RC circuit in which a capacitor and a resistor are connected in parallel are connected in series;
The oscillation frequency region of the resonance circuit is set to a range of 308 to 311 kHz, or 340 to 370 kHz,
Detecting the self-inductance of the high-frequency oscillation coil when the conductive coil is close to the high-frequency oscillation coil in each of the conductive circuit conduction and non-conduction states;
The wear is detected by the amount of change in the self-inductance of the high-frequency oscillation coil when the conductive sensor part is disconnected due to wear of the cutting edge part of the throw-away tip and the conductive circuit becomes non-conductive. A method for detecting wear of a throw-away tip, characterized in that: In the method for detecting wear of a throw-away tip according to claim 4,
By detecting a voltage value or a current value of the RC circuit that causes a difference due to a change in the self-inductance of the high-frequency oscillation coil of the resonant circuit between when the conductive circuit is conductive and non-conductive, the amount of change in the self-inductance A method for detecting the wear of a throw-away tip, characterized in that: A milling cutter in which a throwaway tip provided with a conductive sensor portion made of a conductive film in the vicinity of the cutting edge is attached to the tip, a milling arbor for mounting this milling cutter, and this milling arbor as a milling tool rotating shaft Drive key for positioning with respect to,
In the milling arbor, a conductive coil is installed at a position away from the drive key in the circumferential direction, and the conductive coil and the conductive sensor unit are connected in series to form a conductive circuit,
A non-contact type high-frequency oscillation coil is disposed close to the outside of the rotation path of the conductive coil, and the high-frequency oscillation coil is periodically positioned at a position where the high-frequency oscillation coil faces the conductive coil and a position where the high-frequency oscillation coil does not face each other. A resonant circuit in which an RC circuit that is arranged so as to change and an RC circuit in which a resistor and a capacitor are connected in parallel is connected in series is configured, and an oscillation frequency region of the resonant circuit is 308 A milling tool , which is set in a range of ˜311 kHz or 340 to 370 kHz and includes a detection unit that detects a voltage value or a current value of an RC circuit of the resonance circuit. The milling tool according to claim 6, wherein
A milling tool, wherein the conductive circuit is provided with a tuning capacitor connected in series with the conductive sensor unit and the conductive coil.

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