JP2006281353A - Tool tip position detecting method, work machining method and abrasion state detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the tool tip position with high accuracy in machining a workpiece. <P>SOLUTION: According to the tool tip position detecting method, a reference block 1 having an inclined surface 1a and a reference surface 1b is mounted on a table of a machine tool through a chuck 2, for example. A cutting tool 3 is scanned parallel to the reference surface 1b and at a fixed speed (v). By this scanning, the tip of the knife edge 4 of the cutting tool 3 is abutted on a certain point of the inclined surface 1a, and after that, the inclined surface 1a is continuously cut to the end of the reference block 1, and the upper part thereof is cut and removed. Simultaneously with scanning, the time varying electric characteristic between the cutting tool 3 and the reference block 1 is measured. By the above operation, the tool tip position is detected with high accuracy. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for detecting an accurate separation distance between a workpiece (workpiece) and a tool, and more specifically, a tool tip position detection method and a workpiece for positioning a tool with high accuracy on a workpiece to be machined. It relates to the processing method.

2. Description of the Related Art Conventionally, in machining a workpiece made of a metal material or the like, a machine tool that performs machining by using a linear motion or rotational motion relative to a workpiece of a tool such as a milling cutter, an end mill, or a drill has been widely used.
In this processing, it is important to accurately grasp the separation distance of the tool from the workpiece surface. In particular, in an NC machine tool that numerically controls various movements of a machine tool using a servo motor, for example, it is essential to detect the distance with high accuracy. When the cutting edge of the tool is replaced as a throw-away tip, it is necessary to accurately adjust the position of the newly attached tip at the tool tip when the worn tip is replaced with a new tip.

The distance of the tool tip from the workpiece surface can be easily measured with a digital height gauge when the workpiece is placed horizontally on a table of a machine tool via a chuck, for example. This is a contact-type measuring method, using a digital height gauge attached to the head holding part of the machining head that supports the tool and moves vertically and vertically, and the height when the cutting edge comes into contact with the workpiece surface. Using the height as a reference point, reading is performed from the height gauge.
As another method for measuring the relative position or displacement in a non-contact manner, a method using a laser beam is known (see, for example, Patent Document 1).
JP 11-300581 A

However, in the method using the height gauge in the contact type, the measurement accuracy of the distance between the tool and the workpiece is at most about 1 μm even if the accuracy is improved by a dial type height gauge or the like. For this reason, there is a problem that it is very difficult to control the processing accuracy to 0.1 μm or less in general.
In the method using the optical interference of the laser beam, the measurement accuracy is improved if a laser beam having a short wavelength and a single wavelength is used. The separation distance can be accurately measured up to about the laser wavelength, and an accuracy of 0.1 μm or less can be sufficiently obtained. However, in this case, there has been a problem that optical equipment such as a laser oscillator and a sensor becomes expensive, and the measurement system at the tip of the tool becomes complicated and difficult to put into practical use.

  The present invention has been made in view of the above circumstances, and provides a tool tip position detection method and a workpiece machining method capable of detecting the relative separation distance between the workpiece and the tool with high accuracy. For the purpose.

  In order to achieve the above object, a tool tip position detection method according to the present invention includes a first plane and a second plane that face each other in machining a workpiece, and the first plane is the second plane. A reference block having a fixed inclination angle with respect to a plane is used, a tool used for the machining is arranged on the first plane, and the tip of the tool is at least in contact with the first plane from a non-contact state. Scanning the tool horizontally with respect to the second plane at a constant speed, and measuring the change in electrical characteristics between the tool and the reference block together with the scanning. The tip position of the tool is detected from the change in the electrical characteristics.

  In the above invention, in the step of horizontally scanning the tool on the second plane, a plurality of scans having different arrangement positions on the first plane are performed at the same constant speed, and measurement is performed in each scan. The relative difference in the tip position of the tool in the plurality of scans is detected from the difference in the change in the electrical characteristics.

  In a preferred aspect of the invention, the electrical characteristic is a capacitance, electrical resistance, or impedance between the tool and the reference block made of a conductive material.

  According to the above invention, the absolute or relative tip position detection of the tool can be performed with high accuracy and in a simple manner. And when exchanging the cutting edge of a tool as a throw-away tip, accurate position adjustment at the tool tip of a newly attached tip can be easily performed.

  In the workpiece machining method of the present invention, the tool tip position detection method detects the tool tip position, and then feeds back the detected value to a numerical control device of a machine tool. The workpiece surface is processed by correcting the distance.

  According to the above invention, a fine and highly accurate processed surface can be easily formed on the workpiece surface.

The method for detecting a wear state of a tool according to the present invention includes a first plane and a second plane that are opposed to each other, and the first plane has a constant inclination angle with respect to the second plane. Using blocks,
A tool to be used for the machining is arranged on the first plane, and the tool is placed horizontally with respect to the second plane until the tip of the tool comes into contact with the first plane at least from a non-contact state. Scanning in a direction at a constant speed;
A step of measuring a change in electrical characteristics between the tool and the reference block together with the scanning, and a first step of detecting a tip position of the tool from the change in the electrical characteristics;
A second step of machining the workpiece using the tool;
Using the reference block used in the first step, the tool is arranged at a position separated from the position in the first step on the first plane of the reference block, and the tip of the tool is the first block. The tool is scanned in a horizontal direction with respect to the second plane at a constant speed from a non-contact state to at least a contact plane, and a change in electrical characteristics between the tool and the reference block is performed together with the scan. A third step of detecting a tip position of the tool from the change in the electrical characteristics and inspecting a wear state of the tool in comparison with the tip position of the tool measured in the first step. And a step.
That is, the tip position of a new tool is detected using a reference block, the tool is actually used, and the tip position of the tool is measured again in a different area using the same reference block. By comparing these, the wear state of the tool can be detected.

  According to the configuration of the present invention, it is possible to detect the tip position of the tool with respect to the workpiece with high accuracy in the processing of the workpiece, and it is possible to easily process the workpiece with high accuracy.

Several preferred embodiments of the present invention will be described below with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.
(Embodiment 1)
The tool tip position detection method according to the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a reference block 1 for height measurement, which is a feature of the present invention, and a diagram showing scanning of a tool. Here, the tool is not particularly limited, and examples thereof include a bite type tool, a milling type tool, and a grindstone type tool. In the following embodiment, an example in which a bite type tool is used as a tool will be described.

  As shown in FIG. 1, the upper surface 1a of the reference block 1 is a flat inclined surface having a constant inclination angle θ with respect to the reference surface 1b, where the reference block 1b is the bottom surface of the reference block. . Here, the inclination angle θ is formed at a minute angle of, for example, tan θ = 0.2 or less. The reference block 1 is preferably composed of a conductor material as will be described later.

The reference block 1 is attached via a chuck 2 on a table of a normal machine tool. Then, the cutting tool 3 is lowered on the reference block 1, and the cutting edge 4 is set at a predetermined height position where the cutting edge 4 is not in contact with the inclined surface 1 a of the reference block 1. Here, the cutting edge 4 is made of cemented carbide, diamond, ceramics, or the like.
Next, after the cutting tool is set at a predetermined height as described above, the cutting tool 3 is scanned so as to be parallel to the reference plane 1b and at a constant speed v. By this scanning, as shown in FIG. 1, the tip of the cutting edge 4 of the cutting tool 3 comes into contact with the inclined surface 1a, and thereafter, the inclined surface 1a is cut to the end of the reference block 1, Will be removed by cutting.

  Then, along with the scanning of the byte 3, the time change of the electrical characteristics between the byte 3 and the reference block 1 is measured. For this electrical characteristic, a coupling capacitance (capacitance) between the bit 3 and the reference block 1 is suitable. Alternatively, it may be an electrical resistance or impedance between the bit 3 and the reference block 1.

Next, an equivalent circuit in the measurement of the electrical characteristics will be described with reference to FIG. Here, FIG. 2A is an equivalent circuit diagram in the case of measuring the time variation of the capacitance, and FIG. 2B is an equivalent circuit diagram in the case of measuring the time variation of the electric resistance or impedance. is there. When measuring a change in capacitance with time, a fixed capacitor 6 may be connected in series with the capacitance 5 between the bit 3 and the reference block 1. Then, for example, a 10 kHz AC power supply 7 is connected to the series capacitance, and the capacitance value obtained by connecting the capacitance 5 and the fixed capacitance in series is monitored by the measuring unit 8.
Alternatively, as shown in FIG. 2B, a fixed resistor 10 is connected in series with the resistor 9 between the bit 3 and the reference block 1. Then, for example, an AC power supply 7 of 10 kHz is connected between them, and the resistance value or impedance in which the resistor 9 and the fixed resistor 10 are connected in series is monitored by the measuring unit 8a.

FIG. 3 shows an example in which the time variation of the capacitance is measured simultaneously with the scanning of the cutting tool 3 shown in FIG. 1 using the equivalent circuit of FIG. In FIG. 3, the horizontal axis represents the scanning time, and the vertical axis represents the output value (capacitance value) in the measurement unit 8. Here, the scanning speed (feed speed) of the cutting tool 3 is set to 300 mm / min.
As shown in FIG. 3, the output value is a signal that changes over time in a substantially rectangular shape. In other words, the signal rises substantially stepwise at a certain point and falls again stepwise after a certain time interval T has elapsed. The time-varying signal of this capacitance value is generated as follows.
As described above, when the cutting edge 4 of the cutting tool 3 is not in contact with the inclined surface 1a of the reference block 1, the capacitance value gradually increases in the scanning at the constant speed v shown in FIG. And if the front-end | tip of the blade edge | tip 4 contacts a light touch in the place with the inclined surface 1a, the said front-end | tip and the inclined surface 1a will be electrically connected. When the cutting edge 4 is a conductive material, the capacitance value increases rapidly to near infinity. Here, as described with reference to FIG. 2A, the variable capacitance 5 is connected in series with the fixed capacitance 6, so that the capacitance value of the measurement unit 8 increases rapidly to near infinity. In response, it rises in a stepped manner up to the capacitance value of the fixed capacitor 6. In FIG. 1, since the electrical connection continues while the cutting edge 4 is cutting the inclined surface 1a, the capacitance value remains close to infinity and becomes the rectangular capacitance value. When the cutting edge 4 passes the end of the reference block 1, the cutting edge 4 of the cutting tool 3 again comes into non-contact with the reference block 1, and the capacitance value suddenly decreases.

From the above, it can be seen that the time interval T shown in FIG. 3 indicates the time interval at which the cutting edge 4 of the cutting tool 3 abuts against the inclined surface 1a of the reference block 1 and cuts the upper part thereof. Here, the cutting tool 3 is always scanned horizontally with respect to the reference plane 1b. Further, even when the cutting edge 4 is made of an insulating material such as ceramics or coated with an insulating material, a signal with a capacity that changes with time can be obtained as in FIG.
As shown in FIG. 1, the distance from the point where the tip of the blade edge 4 contacts the inclined surface 1a to the end of the reference block 1 is X, and the distance from the reference surface 1b at the end of the reference block 1 is X. The height is H ₀ and the height position of the tip of the blade edge 4 is Y. In this way, X = vT. From FIG. 1, since H ₀ −Y = X tan θ, the following equation (1) is obtained.

Y = H ₀ −vTtanθ (1)

In this way, the absolute position of the cutting tool tip from the reference surface 1b can be detected. For example, as described above, when tan θ = 0.2 and v = 300 mm / min, if T = 0.1 msec, vT tan θ = 0.1 μm. From the expression (1), it is detected that the tip height of the cutting edge 4 of the cutting tool 3 is at a position of (H ₀ -0.1 μm) from the reference surface 1b.

  The measurement results shown in FIG. 3 are obtained when the capacitance is measured by the equivalent circuit shown in FIG. 2A, but the electrical resistance is measured as in the equivalent circuit of FIG. 2B. However, it has been confirmed that similar results can be obtained. However, in the case of measuring the electrical resistance, the time-varying signal of the output value shown in FIG. 3 falls in a substantially step shape when the tip of the blade edge 4 comes into contact with the inclined surface 1a, and The signal rises stepwise after a certain time interval T has elapsed.

In any case, in the byte tip position detection method using such a reference block 1, the accuracy depends on the resolution of the signal time interval T as shown in FIG. That is, it greatly depends on the time resolution when measuring the time change of the electrical characteristics. Further, it also depends on the inclination angle θ of the reference block 1 and the surface roughness of the inclined surface 1a described later. Normally, the accuracy is improved as θ or the surface roughness is reduced.
In the examination so far, it has been confirmed that the accuracy of detecting the tip position of the cutting tool is possible up to about 0.01 μm (10 nm).

  In the embodiment described above, the byte 3 is scanned with respect to the reference block 1, but conversely, the byte 3 is fixed, the movable table is moved, and the reference block 1 above is scanned. Is the same.

  Next, the reference block 1 will be described with reference to FIG. FIG. 4 is a perspective view of the reference block 1. The reference block 1 is formed of a conductive material that is relatively easy to cut, such as oxygen-free copper. Alternatively, a nickel-plated surface is also suitable. The size of the reference surface 1b, which is the bottom surface, is, for example, a square, its size is 20 mm square, and its height is about 10 mm. And inclination angle (theta) with respect to the reference plane of inclined surface 1a should just be an angle which becomes tan (theta) = 0.1-0.2.

  In such a reference block 1, the smoothness of the inclined surface 1a is important as described above. Therefore, the inclined surface 1a is mirror-polished so that the surface roughness is 10 nm or less. The reference surface 1b is preferably mirror-polished in the same manner. By polishing the bottom surface in this way, the inclination angle θ can be formed with high accuracy.

  Next, another example of the present embodiment will be described with reference to FIG. This example shows a case where the relative tip position of the cutting tool is detected with high accuracy. FIG. 5A is a cross-sectional view similar to FIG. 1 and shows a state in which the cutting edge 4 of the cutting tool 3 scans on the inclined surface 1a. Here, a first scanning position 11, a second scanning position 12, and a third scanning position 13 that are horizontal to the reference plane 1b are shown. The scanning speed (feeding speed) v of the cutting tool 3 at the scanning position (11, 12, 13) is the same. FIG. 5B shows the rising area of the rectangular signal that occurs in the measurement of the capacitance between the byte 3 and the reference block 1 as described in FIG.

From the rise time difference, the relative tip position of the byte is detected with high accuracy as follows. That is, if the rise time difference is t, the relative difference in height position between the scans can be detected by v × t (tan θ).
As shown in FIG. 5B, the capacitance rise time at the second scan position 12 is delayed by t1 with respect to the capacitance rise time at the third scan position 13, and the first scan position. 11, the rise time of the capacitance is delayed by t2. In this case, the height of the second scanning position 12 is detected as being relatively higher than the third scanning position 13 by v × t1 (tan θ). Similarly, the height of the first scanning position 11 is detected as being relatively higher than the third scanning position 13 by v × t2 (tan θ).

  Here, even if the height position of the third scanning position 13 is not detected, the relative position detection between the scans can be performed with high accuracy. Also in this case, the accuracy of relative position detection is the same as in the case of absolute position detection as described above. And it has been confirmed that the accuracy can be about 10 nm.

  As described above, the reference block 1 having the inclined surface 1a having a constant angle is used, and the cutting tool is moved at a constant speed in the horizontal direction until the cutting edge 4 which is the tip of the cutting tool 3, for example, contacts at least the inclined surface 1a as a tool. Scan. By measuring the temporal change in electrical characteristics between the cutting tool and the reference block 1 along with the scanning, it becomes possible to detect the absolute or relative tip position of the cutting tool with high accuracy and simplicity.

  Here, when measuring the time change of the electrical characteristics, a method of measuring the time change of the impedance using a resonance circuit by electromagnetic coupling can be used. In this case, the resistance against external noise in the machine tool is very high. This will be described later in the specific example of the second embodiment.

  Further, in the above embodiment, even when the tool is a tool other than the cutting tool, such as a milling tool, a grindstone tool, or a drill, the tip position can be detected in the same manner. Then, using the tool, for example, turning, milling, grinding, drilling, and the like can be performed with high accuracy.

For example, as shown in FIG. 6A, the work 15 fixedly held by the rotary chuck 14 is rotated. Then, the cutting edge 4 of the cutting tool 3 whose tip position is detected with high accuracy by the above-described method is brought into contact with the rotating work 15 and the surface thereof is cut.
Alternatively, as shown in FIG. 6 (b), the tip position of the milling cutter 16 which is a multi-blade tool is detected with high accuracy by the same method as that for the cutting tool 3 described above, and then the rotating milling cutter 16 is moved to the workpiece. 15 is contacted and the surface is processed.
Alternatively, as shown in FIG. 6C, for example, a grindstone 17 is used as a tool, the tip position is detected with high accuracy by the same method as in the above-described tool 3, and then the grindstone 17 that rotates is moved to a work 15 The surface is ground and the surface is ground. Here, the workpiece 15 may perform a linear motion.

  In the tool tip position detection method according to the above-described embodiment, the detection accuracy becomes 10 times or more in each conventional tool position detection, and greatly improves. In addition, when the cutting edge of the tool is replaced as a throw-away tip, it is possible to easily perform accurate position adjustment at the tip of the newly attached tip.

(Embodiment 2)
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the tool tip position detection method described in the first embodiment will be described together with a workpiece machining method based on a specific example of a machine tool operated by a numerical control (NC) device. Here, FIG. 7 and FIG. 8 are schematic configuration diagrams of different machine tools. In the drawing, the components described in the first embodiment are denoted by the same reference numerals, and will be specifically described in accordance with the operation of the machine tool. Here, the description thereof is the same as that described with reference to FIGS.

First, a schematic configuration of the machine tool 21 will be described. As shown in FIG. 7, the machine tool 21 has a base 23 provided at the lower portion of the main body 22 and a head holding portion 24 fixed to the upper portion of the main body 22 so as to face each other. On the base 23 is provided a table 25 that air slides by, for example, a linear guide, and the reference block 1 is fixedly held on the table 25 via the chuck 2. Similarly, the workpiece 15 is placed via the chuck 2.
In addition, a machining head 27 including a cutting tool support 26, a cutting tool 3, and a cutting edge 4 is attached to the head holding unit 24. Here, the machining head 78 has a structure capable of linearly moving vertically.

An electrical characteristic measuring unit 28, an arithmetic processing unit 29, and an NC device 30 for measuring the electrical characteristics between the bit 3 and the reference block 1 are provided. Here, the electrical characteristic measuring unit 28 has the circuit configuration as described with reference to FIG. 2, and measures the time change of the capacitance, electrical resistance, or impedance between the bit 3 and the reference block 1 as described above. To do. And the arithmetic processing part 29 receives the said electrical characteristic from the electrical characteristic measurement part 28, for example, receives the feed speed v of the table 25 from NC apparatus, performs a calculation which was demonstrated in 1st Embodiment, and was mentioned above. Calculate absolute absolute or relative tool tip height position. Although not shown in FIG. 7, data such as the inclination angle θ of the reference block 1 and the height H ₀ of its end can be generated from an input unit connected to the arithmetic processing unit 29.

Next, the operation of the machine tool 21 will be described. Before processing the surface of the workpiece 15, the height position of the cutting edge 4 of the cutting tool 4 from the reference surface 1b is detected by the method described in FIGS. 1 to 3, and that position is set as the zero point in the height direction. Then, after detecting the tip position of the cutting tool, the surface of the workpiece 15 having a predetermined thickness is processed. Here, the thickness of the workpiece is measured in advance and input to the NC device 30 or the arithmetic processing unit 29. Then, the NC device 30 adjusts the height of the bite support portion 26 of the machining head 27 from this thickness and the above H ₀ value, and processes the surface of the workpiece 15 to an appropriate depth.

Alternatively, before processing the surface of the workpiece 15, the height position of the cutting edge 4 of the cutting tool 3 from the reference surface 1b is detected by the method described in FIG. In this case, the heights of the plurality of byte scans are relatively detected. Here, the height of the cutting tool is set by a digital height gauge attached to the head holding unit 24. Therefore, the height gauge can be corrected based on the detected relative height. The NC device 30 drives the main body 22 based on the value corrected in this manner, and processes the surface of the workpiece 15.
Alternatively, the relative height difference is processed and transferred to the surface of the work 15 as it is to form a processed surface having the height difference.

  Next, a schematic configuration of the machine tool 31 will be described. This example is another specific example in the case of machining a workpiece by rotating the tool. As shown in FIG. 8, the machine tool 31 includes a base 23 provided at the lower portion of the main body 32, a main shaft 34 that is rotated by a motor unit 33 provided at the upper portion of the main body 32, and a bearing 35. Here, the main shaft 34 is rotationally driven with high precision by an air bearing. For example, an end mill 36, which is a tool, is attached to the main shaft 34 so as to rotate. An air sliding table 25 is provided on the base 23, and the reference block 1 is fixedly held on the table 25 via the chuck 2. Similarly, the workpiece 15 is placed via the chuck 2.

  Here, the above-described resonance circuit 38 for measuring the time change of the electrical characteristics includes the counter electrode 37 disposed on the outer peripheral portion of the main shaft 34, the annular circuit coil 39, the end mill 36, the reference block 1, and the table 25. Etc.

  The counter electrode 37 is, for example, a ring-shaped conductor, and has an inner diameter slightly larger than the outer diameter of the main shaft 34. The outer surface of the main shaft 34 and the inner surface of the counter electrode 37 constitute an air capacitor and are capacitively coupled. The center of the counter electrode 37 is held so as to coincide with the axis of the main shaft 34, and the coupling capacity is substantially constant regardless of the stationary state and the rotating state of the main shaft.

  A transmitting coil 40 that weakly electromagnetically couples (loosely couples) to the annular circuit coil 39 is disposed and connected to the transmitting circuit 41. In this way, an electromotive force is generated in the resonance circuit 38 through the mutual inductance M. The detection circuit 42 measures the impedance of the resonance circuit 38 or the transmission circuit 41.

Here, the resonance frequency of the resonance circuit 38 is set to a high frequency range of, for example, several tens of kHz to several hundreds of kHz. When the tip of the end mill 36 changes from a non-contact state to a contact state with respect to the inclined surface 1a of the reference block 1 by scanning the base 25, the impedance to be measured is It is configured to change stepwise. For this purpose, for example, when the tip of the end mill 36 changes from a non-contact state to a contact state, the coupling capacitance between the main shaft 34 and the counter electrode 37, an annular shape so that the resonance circuit 38 changes from non-resonance to resonance. The inductance of the circuit coil 39, the frequency of the power source of the transmission circuit 41, etc. are set. Or conversely, it is set to change from resonance to non-resonance. Thus, the time change of the impedance is measured.
The above-described change from non-resonance to resonance or vice versa occurs when the coupling capacity changes during the transition from the non-contact state to the contact state between the tip of the end mill 36 and the inclined surface 1a of the reference block 1. It is. From this, it can be said that the above method is basically the same method as in FIG.
According to the above method, it is possible to select a frequency that avoids the natural frequency of the external noise generated around the machine tool as the frequency of the power source of the transmission circuit, and the resistance of the external noise is greatly improved.

  An arithmetic processing unit 29 and an NC device 30 are provided together with an electric characteristic measuring unit 28a for measuring electric characteristics including the transmission circuit 41, the detection circuit 42, and the like. Here, the arithmetic processing unit 29 receives the change in the electric characteristics from the electric characteristic measuring unit 28a, receives the feed speed v of the table 25 from the NC device, for example, and performs the calculation as described in the first embodiment. The absolute or relative end mill tip height position as described above is calculated.

  Next, the operation of the machine tool 31 will be described. Before processing the surface of the work 15 with the end mill 36, the height position from the reference surface 1b of the end mill 36 is detected as described above, and the position is set as the zero point in the height direction. Then, after detecting the tip position of the end mill 36, the surface of the workpiece 15 having a predetermined thickness is processed. Here, the thickness of the workpiece is measured in advance and input to the NC device 30 or the arithmetic processing unit 29. Then, the NC device 30 adjusts the relative position between the end mill 36 and the surface of the work 15 based on the thickness and the zero point, and processes the surface of the work 15 to an appropriate depth.

Alternatively, before processing the surface of the workpiece 15, the height position of the end mill 36 from the reference surface 1b is detected by the same method as described in FIG. In this case, the height of the scanning position of the plurality of end mills 36 is relatively detected. Here, the height of the end mill 36 is set by the spindle 34 or the table 25. Therefore, based on the detected relative height, the spindle 34 or the table 25 can be adjusted to correct the height of the end mill 36. Based on the corrected value, the NC device 30 drives the main body 32 to process the surface of the workpiece 15.
Alternatively, the relative height difference is processed and transferred to the surface of the work 15 as it is to form a processed surface having the height difference.

  In this example, the tip position of the tool can be detected even in the case of the end mill 36 in which the tool rotates. In this case, as described above, the resistance against external noise in the machine tool is very high.

  In the second embodiment, in machining a workpiece using a tool, by detecting the tip position with high accuracy, a machining surface with an accuracy of, for example, 0.1 μm or less on the surface of the workpiece 15 can be easily obtained. .

(Embodiment 3)
Next, a third embodiment of the present invention will be described.
In this embodiment, the tip position is detected for the tip position obtained by the tip position detection method and the tool after the workpiece has been machined a plurality of times using the tool. The present invention relates to a method for detecting the wear state.
Here, FIG. 9 is a diagram for explaining the method of the present embodiment. In the figure, the same reference numerals are given to those described in the first and second embodiments, and a detailed description thereof is given. Is omitted.
In FIG. 9, a region A is a first cutting region of the reference block 1, and a region 2 is a second cutting region of the same reference block. As can be seen in the figure, the height difference Hw between the bottom of the region A and the bottom of the region B corresponds to the amount of wear of the tool. Actually, the graph shown in FIG. 3 is obtained in the detection of the tip position twice. In these graphs, the wear amount can be estimated by the difference in the scanning time T.

The form of Mr. Honji will be described in more detail.
In the first step of this embodiment, a reference block having a first plane and a second plane facing each other, the first plane having a constant inclination angle with respect to the second plane is provided. A tool used for the machining is disposed on the first plane, and the tool is moved relative to the second plane until the tip of the tool is at least in contact with the first plane from a non-contact state. A step of scanning at a constant speed in a horizontal direction, and a step of detecting a tip position of the tool from the change in the electrical characteristics by the step of measuring the change in electrical characteristics between the tool and the reference block together with the scanning. .

  Next, the second step is a step of machining the workpiece using the tool. In this step, the tool is actually used, resulting in wear of the tip.

  Subsequently, in the third step, the reference block used in the first step is used, and the tool whose tip is worn is shifted from the position in the first step on the first plane of the reference block. The tool is scanned at a constant speed in a horizontal direction relative to the second plane until the tip of the tool is at least in contact with the first plane from the non-contact state; And measuring a change in electrical characteristics between the tool and the reference block, and detecting a tip position of the tool from the change in electrical characteristics. It is a step of inspecting the wear state of the tool from information on the tip position of the tool measured in the first step and the tip position detected in this step.

  In the present embodiment composed of these steps, the tip position can be detected in the same manner as in the first embodiment.

(Other variations)
Although the preferred embodiments of the present invention have been described above, the above-described embodiments do not limit the present invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

  Specifically, various other configurations are conceivable in the measurement of the temporal change in electrical characteristics between the tool and the reference block described in the above embodiment. However, the basic configuration is to measure a change in impedance using a change in induced current between the tip of the tool and the inclined surface of the reference block.

  In the above-described embodiment, an example of measuring the temporal change in electrical characteristics between the tool and the reference block has been described. However, an ultrasonic wave is applied between the tool and the reference block, and the ultrasonic wave is transmitted along with the scanning of the tool. You may measure a time change. Alternatively, an audio signal may be applied and a time change in the transmission may be measured.

  Further, the reference block used in the present invention is not limited to the one described in FIG. 4, and may be a finer structure having a dimension of, for example, 1 mm or less. And the place which fixes and hold | maintains a reference | standard block is not limited to the place demonstrated in 2nd Embodiment, For example, the workpiece | work surface may be sufficient.

In addition, it should be noted that the present invention can be similarly applied to other finishing processes such as polishing, lapping, and polishing.
This lapping is a method of precisely polishing the surface using abrasive grains, but the tool portion can be measured by adopting the method of the above embodiment except for abrasive grains. Polishing is performed by attaching a buff to a tool and polishing. However, in this method, it is preferable to apply the method of the above embodiment when the buff is wound around the tool. .

It is sectional drawing which shows the scanning of the reference | standard block and byte for describing Embodiment 1 of this invention. It is an equivalent circuit diagram which measures the electrical property between a reference | standard block and a byte with the said scan of a byte. It is a graph which shows an example of the time change of the said electrical property. It is a perspective view which shows an example of the said reference | standard block. It is a figure which shows the scanning position of the byte | cutting | tool on the inclined surface of the reference | standard block for demonstrating Embodiment 1 of this invention, and the difference in the electrical property. It is sectional drawing which shows the example of a process of the tool in embodiment of this invention, and a workpiece | work using the same. It is a block diagram of the machine tool for demonstrating Embodiment 2 of this invention. It is a block diagram of another machine tool for demonstrating Embodiment 2 of this invention. It is the schematic for demonstrating Embodiment 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reference block, 1a ... Inclined surface, 1b ... Reference surface, 2 ... Chuck, 3 ... Bite, 4 ... Blade edge, 5 ... Capacitance, 6 ... Fixed capacity, 7 ... AC power supply, 8, 8a ... Measurement part, DESCRIPTION OF SYMBOLS 9 ... Resistance, 10 ... Fixed resistance, 11 ... 1st scanning position, 12 ... 2nd scanning position, 13 ... 3rd scanning position, 14 ... Rotary chuck, 15 ... Workpiece, 16 ... Milling, 17 ... Grinding wheel, DESCRIPTION OF SYMBOLS 21, 31 ... Machine tool, 22, 32 ... Main body, 23 ... Base, 24 ... Head holding part, 25 ... Table, 26 ... Tooling support part, 27 ... Processing head, 28, 28a ... Electrical property measuring part, 29 ... Calculation Processing unit, 30 ... NC device, 33 ... Motor unit, 34 ... Main shaft, 35 ... Bearing, 36 ... End mill, 37 ... Counter electrode, 38 ... Resonant circuit, 39 ... Coil for annular circuit, 40 ... Transmitting coil, 41 ... Transmission Circuit, 42 ... detection circuit

Claims (5)

In machining the workpiece,
Using a reference block having a first plane and a second plane facing each other, the first plane having a constant inclination angle with respect to the second plane;
A tool to be used for the machining is arranged on the first plane, and the tool is placed horizontally with respect to the second plane until the tip of the tool comes into contact with the first plane at least from a non-contact state. Scanning in a direction at a constant speed;
And measuring the change in electrical characteristics between the tool and the reference block along with the scanning,
A tool tip position detection method, wherein the tool tip position is detected from a change in the electrical characteristics. In the step of scanning the tool horizontally on the second plane,
A plurality of scans having different arrangement positions on the first plane are performed at the same constant speed, and the tip position of the tool in the plurality of scans is determined from the difference in change in the electrical characteristics measured in each scan. The tool tip position detecting method according to claim 1, wherein a relative difference between the two is detected.   3. The tool tip position detection method according to claim 1, wherein the electrical characteristic is a capacitance, an electrical resistance, or an impedance between the tool and the reference block made of a conductive material. After detecting the tip position of the tool by the tool tip position detection method according to claim 1, 2, or 3,
A workpiece machining method, wherein the detected value is fed back to a numerical control device of a machine tool, the distance between the tool and the workpiece is corrected, and the workpiece surface is machined. Using a reference block having a first plane and a second plane facing each other, the first plane having a constant inclination angle with respect to the second plane;
A tool to be used for the machining is arranged on the first plane, and the tool is placed horizontally with respect to the second plane until the tip of the tool comes into contact with the first plane at least from a non-contact state. Scanning in a direction at a constant speed;
A step of measuring a change in electrical characteristics between the tool and the reference block together with the scanning, and a first step of detecting a tip position of the tool from the change in the electrical characteristics;
A second step of machining the workpiece using the tool;
Using the reference block used in the first step, the tool is arranged at a position separated from the position in the first step on the first plane of the reference block, and the tip of the tool is the first block. The tool is scanned in a horizontal direction with respect to the second plane at a constant speed from a non-contact state to at least a contact plane, and a change in electrical characteristics between the tool and the reference block is performed together with the scan. A third step of detecting a tip position of the tool from the change in the electrical characteristics and inspecting a wear state of the tool in comparison with the tip position of the tool measured in the first step. And a tool wear state detecting method comprising the steps of:

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