JPH0223300B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic measuring device that is inserted into the main shaft of a machine tool, particularly a machining center, and measures the dimensions of an object to be measured.

BACKGROUND ART Conventionally, with measurement tools that are used by being inserted into a tool insertion hole of a spindle that rotates like a tool, there has been a problem in how to extract a measurement signal.

For example, in a contact detection automatic measuring device that uses the object to be measured, that is, the workpiece, as a conductor, the condition of the column after sliding is affected by the state of the oil film that forms on the sliding surface between the bed and the column that supports the contact. The posture changed, and the contact position of the contactor on the workpiece was unstable, and there was a limit to accuracy.

In addition, there was a delay in the contact signal due to contact, and the time required to read the scale was long, making accurate measurement impossible.

In addition, the sliding column still had a certain amount of flow even after the stop command was issued, and there was no provision to correct this, resulting in a discrepancy between the actual value and the read value. Therefore, there is a problem that there is a certain limit to the accuracy of workpiece measurement.

Furthermore, in a type of measuring tool that has a built-in battery, it is time-consuming to replace the battery every time the battery reaches its lifespan, and a battery-depletion alarm circuit is also required.

In addition, as a non-contact type device, the light from a lamp installed on the measuring tool is detected by a light receiving element installed at the front end of the spindle head, but the detection may be hindered by disturbances such as lighting. The problem was that the transmission and reception of signals became unstable and lacked reliability.

The present invention solves the above-mentioned problems of the conventional automatic measuring device, and in the above-mentioned spindle-mounted measuring tool, when the probe of the measuring tool comes into contact with the object to be measured, an electric signal is generated. A displacement detector that generates the electric signal, a light emitter that emits light in response to this electric signal,
Provided is an automatic measuring device for a machine tool, which is equipped with a solar cell that supplies power to the displacement detector and the light emitter, and a light receiving section provided on the spindle head to detect the modulated light of the light emitter. It is something to do.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic measuring device for a machine tool according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is an overall side view of a horizontal machining center having an automatic measuring device according to the present invention. bed 1
A table 2 is slidably placed on the top, and a workpiece W is attached to an indexing table 3 placed on the table 2. A column 5 is placed on a bed 4 connected to the bed 1 so as to be slidable in a horizontal direction perpendicular to the sliding direction of the table 2. A spindle head 6 is supported on the side surface of the column 5 so as to be movable in the vertical direction.
The tool storage magazine 7 that can be rotated and indexed is mounted, and the tool socket into which the required tools are inserted is removed from the tool storage magazine 7 by the intermediate transfer device 8 and positioned parallel to the spindle axis, and then the tools are replaced. By means of the arm 9, the tool in the spindle and the intermediate conveyor device 8
Replace with the tool.

The measuring tool 10 used in the present invention has almost the same external structure as a normal cutting tool, is stored in a tool storage magazine 7, and is stored in a tool storage magazine 7 as needed.
It is inserted into the main spindle by means of the intermediate conveyance device 8 and tool exchange arm 9. In order to detect the position where the probe 11 at the tip of the measuring tool 10 contacts the workpiece W, a linear scale 12 is fixed to the lower rear surface of the column 5, and a slider 13 paired with the linear scale 12 is mounted on the bed 4. Fixed on the side. Further, a linear scale 14 is fixed to the side surface of the column 5, and a slider (not shown) paired with the linear scale 14 is fixed to the spindle head 6 side. Similarly, although not shown, a pair of linear scales and sliders are also fixed to the bed 1 and the table 2.

2 and 3 are longitudinal sectional views of the spindle head 6. FIG. In the spindle head 6, the spindle 15 has bearings 16A to 16.
A tool insertion hole 17 for receiving a cutting tool and a measuring tool 10 is formed at the tip of the main shaft 15. Main shaft 1
A tension rod 19 is inserted into a through hole 18 formed at the axis of the main shaft 15 so as to be able to reciprocate and slide parallel to the axis of the main shaft 15, and is constantly pulled rearward by a disc spring 20. Three steel balls 21 are incorporated into the tip of the pull rod 19 so as to be movable in the radial direction, and cooperate with the inner cam surface of the cam sleeve 22 into which the tip of the pull rod 19 is slidably fitted. The action moves the steel ball 21 in and out. i.e. pull rod 1
As the tool 9 reciprocates, the steel ball 21 is moved in and out in the radial direction, and engaged with and disengaged from the pull stud 23 at the rear end of the tool. Pull rod 19
A rod 25 that is always urged forward by a spring 24 is inserted into the front part of the tool, and when the tool is taken out from the tool insertion hole 17, it moves forward and attaches to the steel ball 21.
prevents it from falling.

As shown in FIG. 3, a cylinder 26 is fixed to the rear of the spindle head 6, and the cylinder 26 has a large diameter cylinder chamber 26A on the front side and a small diameter cylinder chamber 26B on the rear side. . cylinder chamber 2
A hollow piston 27 is fitted into 6A so as to be slidable in the axial direction. Further, a piston 28 is inserted into the cylinder cavity 26B so as to be able to slide in the axial direction, and a piston rod 28A integral with the piston 28 is inserted into the cylinder cavity 26B.
is slidably fitted into the hollow portion of the piston 27. The cylinder 26 includes a pressure oil passage 29A communicating with the front cylinder chamber of the piston 27, a pressure oil passage 29B communicating with the cylinder chamber between the pistons 27 and 28, and a pressure oil passage communicating with the rear cylinder chamber of the piston 28. 29C are perforated, and by selectively supplying pressure oil to each pressure oil passage 29A, 29B, and 29C, the stop position of the piston 28 can be controlled in three stages.

A pressing rod 30 is screwed onto the tip of the piston rod 28A, and the tip of the pressing rod 30 has a
A sleeve-shaped bearing metal 31 is slidably fitted, and is always urged forward by a spring 32. Furthermore, a bearing metal 33 is fixed to the rear end of the above-mentioned tension rod 19, with which a bearing metal 31 comes into contact. In order to confirm the three stop positions of the piston 28, dogs D-1 and D-2 are screwed into the rear threaded part of the push rod 30, and limit switches LS-1, LS-2, and LS-3 are stepped on. The operation is confirmed by

The unclamping cylinder 26 described above performs different operations depending on whether it is a cutting tool used in normal machining operations or when it is used as a measuring tool 10.
That is, when a normal cutting tool is also inserted into the tool insertion hole 17 of the spindle, if pressure oil is supplied to the pressure oil passage 29C and the pressure oil passages 29A and 29B are connected to the tank side, the piston 28 moves to the most advanced position and pushes the pull rod 19 against the disc spring 20 with the front end face of the push rod 30, releasing the steel ball 21 from the pull stud 23. When the cutting tool is inserted again, the pressure oil passage 29A remains connected to the tank side, pressure oil is supplied to the pressure oil passage 29B, and the pressure oil passage C is connected to the tank side, so that the piston 28 is moved to the most retracted position shown in FIGS. 2 and 3, and the pull rod 19
is retracted by the disk spring 20 to clamp a new cutting tool into the tool insertion hole 17. At this time, a gap is created between the bearing metals 33 and 31, so even if the main shaft 15 rotates and machining starts, there is no fear of heat generation or the like.

When the measuring tool 10 is inserted into the tool insertion hole 17, the pressure oil passage B remains on the tank side, the pressure oil passage C remains supplied with pressure oil, and the pressure oil passage 29
Since pressure oil is supplied to A, pistons 27 and 28
The piston 28 is retracted to an intermediate position due to the difference in pressure receiving area. This allows the pull rod 19
is retracted by the disk spring 20, and the measuring tool 10
is clamped into the tool insertion hole 17.

Next, the internal structure of the measuring tool 10 shown in FIGS. 4 and 5 will be explained in detail. Measuring tool 10
is composed of a head 37, a body 38 and a shank 39, and the head 37 has a lever mechanism 4.
0 is set. This lever mechanism 40 has a front lever 41 to which the probe 11 is attached at the tip.
and a rear lever 42 that comes into contact with a differential transformer to be described later.
The center portion of the front lever 41 is rotatably supported by the head 37 by a pin or the like, and a pin 43 is provided protruding from the middle portion of the front lever 41 near the other end. One end of the rear lever 42 is rotatably supported by the head 37 by a pin or the like, and the tip in front of the pivot pin is supported by the pin so that its downward movement in the figure is linked with the front lever 41. It is in contact with 43. A pin 44 is protruded from the middle part of the rear lever 42 near the other end, and the rear end of the front lever 41 is brought into contact with this pin 44 so that its downward movement in the figure is linked with the rear lever 42. are in contact with each other. Furthermore, one end of a leaf spring 45 fixed to the head 37 is in contact with the pin 44 so as to oppose the rear end of the front lever 41. 46 is a differential transformer as a displacement detector fixed to the head 37, and a slidable slider 47 is provided protruding from the differential transformer 46. The tip of this slider 47 is in contact with the rear end of the rear lever 42, and the slider 47 is in contact with the rear end of the rear lever 42.
7 is constantly urged toward the rear lever 42 by a coil spring 48.

As shown in FIG. 5, if a/b=c/d, the slider 47 moves in both directions (the fifth Both arrows A and B in the figure move the same amount in one direction. Twelve solar cells 49 are mounted on the surface of the body 38, and a light emitter 50 consisting of an infrared light emitting diode or the like is mounted.
There are four at equal intervals of 90 degrees. The body 38 is made of rechargeable Ni-
A CD battery 51 and other circuits are configured and built-in, and a pull stud 23 is screwed into the rear end of the shank 39. A power switch 52 is protruded from the middle part of the shank 39, and this shank part 39 has almost the same shape as the shank of a tool in a machining center, and can be exchanged from the magazine 7 to the tool spindle 15 by the intermediate transfer device 8. ing.

6 and 7 show an example of an electronic circuit built into the body 38 and a block diagram.
53 is a power supply circuit, and the solar cell 49 forming a part of the power supply circuit 53 is connected to a vibrator 54. The output of this vibrator 54 is connected to the primary side of a step-up transformer 55, and the Ni-Cd battery 51 is connected to its secondary side via one circuit of a rectifier transistor 56 and a power switch 52. . An oscillation circuit 57 is connected to the primary coil of the differential transformer 46, and a rectifying and smoothing circuit 58 is connected to the secondary coil, so that the slider 47 slides between the primary and secondary coils. It's getting old. The output side of this rectifying and smoothing circuit 58 is connected to a voltage controlled oscillator 59, and this output is input to a pulse amplifier 60. Pulse amplifier 6
The output of 0 is connected to the four light emitters 50, for example, infrared light emitting diodes (LEDs), and the power supply circuit 53 is connected to the differential transformer 46, the voltage controlled oscillator 59, and the pulse amplifier via the other circuit of the power switch 52. 60 and the light emitting body 50 (hereinafter referred to as the transmitting circuit 6
1). The main shaft 15
When the measuring tool 11 is inserted into the power switch 52, one circuit of the power switch 52 is opened and the other circuit is closed. When the measuring tool 10 is waiting in the magazine 7, one circuit of the power switch 52 is closed, the other circuit is open, and no power is supplied to the transmitting circuit 61. However, the solar cell 49 generates power using irradiation and other lighting in the factory, and in this embodiment, 12 elements are installed in series, and the generated voltage of each element is 0.5V, so the total number is approximately 0.5×12=6.0V
It generates a voltage of After this voltage is generated by a vibrator 54 and boosted by a transformer 55, it is passed through one circuit of the power switch 52, which is rectified by a rectifying transistor 56.
The CD battery is constantly charged.

As shown in FIG. 8, a receiving circuit 62 is attached to the spindle head 6 facing the spindle 15, and this receiving circuit 62 transmits signals from the light emitter 50 to the photoreceptor 6.
3 has, for example, a phototransistor (this photoreceptor 63 also includes a predetermined amplifier) and a waveform shaping circuit 64 to which the output thereof is input. The output of this waveform shaping circuit 64 is connected to an F/V converter 65 via a cable line, etc., and part of the output is input to an AD converter 66, and the other part is input to a threshold setting circuit 67. ing.

68 is an AND circuit, to which the output side of the A/D converter and the output side of the confirmation circuit 69 connected to the setting circuit 67 are respectively connected. The output side of the AND circuit 68 is connected to a data latch circuit 70 that temporarily stores signals, and its output is input to a relay drive circuit 71. The output of the relay drive circuit 71 is input to a reed relay 72 that generates a relay contact signal, and the confirmation circuit 69 is input to a relay drive circuit 73 for generating a squib signal, which will be described later. The output of this relay drive circuit 73 is input to a reed relay 74 that generates a relay contact signal. The outputs of the reed relays 72 are 16-bit binary signals, which are respectively input to the arithmetic units 82. In addition, the output of the reed relay 74 is
5 is connected to the NC squirt signal input circuit. The F/V converter 65, A/D converter 66, AND circuit 68, data latch circuit 70,
Relay drive circuit 71, reed relay 72 and setting circuit 67, confirmation circuit 69, relay drive circuit 73,
The reed relay 74 as a whole is configured as a machine-side control device.

FIG. 9 is an overall block diagram of the automatic measuring device of the present invention, in which the linear scale 12 and the slider 1
The relative position of 3 is input to a scale reader 77 and its value is stored in a memory 78. Reference numeral 79 is a diameter setting section of the measuring head 11, which is used to preset the spherical diameter dimension D ₀ of the measuring head 11. There is. The displacement digital signal that is the output of the reed relay 72 is also connected to the data calculation section 80 via the Di/Do interface 81 and the memory 78, and the data calculation section 80 is equipped with a printer or CRT display 83 for display. In addition to being connected, an NC device 85 that controls the machining center is also connected.

Next, the effect when the measuring element 11 contacts the measurement surface of the workpiece W will be explained. The movement of the probe 11 is transmitted to the slider 47 of the differential transformer 46 via the front lever 41 and the rear lever 42. Therefore,
A DC analog voltage corresponding to the displacement of the slider 47 is output from the DC-operated differential transformer 46 .
This voltage signal is subjected to pulse frequency modulation (PFM) by a voltage controlled oscillator 59, and this PFM signal is amplified by an amplifier 60 to cause the four light emitters 50 to emit light simultaneously. Since this light is infrared, it is invisible to the naked eye, but it is not easily disturbed by lighting inside the factory. The infrared rays of the PFM signal emitted from the light emitter 50 propagate in the air and are received by the light receiver 63 on the spindle head 6 side, which is disposed at an opposing position (the light emitter 5
0 and photoreceptor 60 are an unmatched pair of elements). The received PFM signal is corrected by a waveform shaper 64 to correct the waveform that was distorted during propagation, and is sent to the NC machine side control device 75 through a cable line or the like. The PFM signal is demodulated by the F/V converter 65 and converted into an analog voltage signal similar to the output of the original differential transformer 46. A part of this analog voltage signal is used for subsequent calculation processing.
The signal is converted into a digital signal by the D converter 66 and input to the AND circuit 68, and a portion is further input to the threshold setting circuit 67.

When the measuring element 11 comes into contact with the wall of the work W, the slider 47 is displaced and a corresponding voltage signal is generated. However, this generated voltage signal is not immediately taken into the data calculating section 80, but a predetermined voltage is generated. In other words, when the voltage exceeds the threshold voltage, the data is taken in, and when the voltage exceeds the desired threshold, the NC device 85
This is to enable a skip signal to be sent.

In FIG. 10, the horizontal axis is the displacement (moving distance) of the slider 47 of the differential transformer 46, and the
1 does not come into contact with the workpiece W and the front lever 41 and rear lever 42 do not rotate at the neutral point shown in Fig. 10 n.
(mechanical neutral point). When the measuring stylus 11 comes into contact with the workpiece W and there is a flow of the spindle head 6, the measuring stylus 11 is continuously displaced, for example, in the direction of arrow A in FIG. Accordingly, the front lever 41 and the rear lever 42 rotate, and the slider 47 is displaced by the coil spring 48 in the direction of arrow A in the figure. This displacement moves toward the upper right in graph Q of FIG. Here, the vertical axis represents the output voltage of the differential transformer 46, and an output voltage corresponding to the displacement of the slider 47 is obtained.

The differential transformer 46 is adjusted in advance so that it is equidistant from a position O where the output voltage becomes 0 on a straight line between displacement and output voltage, and is set as a measurement range S. In this way, the mechanical neutral point n of the slider 47 will be on the negative output side far beyond the measurement range.
A threshold setting range Y is set at a location slightly closer to the measurement range S than the neutral point n, and when the threshold setting range is below, that is, from point n on the graph Q to p
Up to this point, the command to stop the column 5, that is, the stop of the spindle head 6 and the probe 11, and the skip signal are not generated from the reed relay 74, and the A/
The displacement digital signal of the D converter 66 does not pass through the AND circuit 68. Therefore, no displacement data signal is read into the data calculation section 80.

In FIG. 12, for example, the measuring element 11 is set at the center of the hole of the workpiece W, and then the measuring element 11 is moved to the right. For example, if the hole diameter is about 10 mm, an additional travel distance of about 12 mm should be programmed into the input tape of the machine tool. If there is no skip signal, the 12mm gauge stylus 11 should move as programmed, but when the skip signal is sent to the NC device 85, the machine tool cancels the remaining programmed movement amount, that is, the 12mm gauge stylus 11 moves as programmed. Stops moving and moves to the next program. At this time, the spindle head 6 supporting the gauge head 11 moves slightly to the right due to inertia. This sliding distance (in units of several microns) is detected as the displacement of the slider 47. Point p in FIG. 10 represents the threshold voltage (displacement) that gives a skip signal to the NC device 85, and this value can be set arbitrarily (set variably using a volume or potentiometer, etc.). This set threshold voltage and the output voltage signal of the F/V converter 65 are compared in a confirmation circuit 69, and when the voltage signal exceeds the threshold voltage point p, a confirmation signal h
is input to the AND circuit 68. At this time, the digital signal passes through the AND circuit 68 and is temporarily stored in the data latch circuit 70. The confirmation signal is amplified by a relay drive circuit 73 and then input to a reed relay 74 to generate a skip signal. This skip signal is input to the skip signal input circuit of the NC device 85, and the spindle head 6 is stopped. However, as described above, the probe 11 is sliding as shown by the arrow u in FIG. 11, and the displacement voltage digital signal is amplified by the relay drive circuit 71 and becomes a relay contact signal.
The data is input to the memory 78 via the interface 81. This displacement voltage digital signal is
At the same time, while the spindle head 6 is sliding, it is read into the memory 78 as a digital signal, and the data calculation section 80 calculates the sliding distance of the spindle head 6 based on this digital signal.

The scale value from the scale reading device 77 is not read until the sliding distance is corrected. The first method of correction is to input a value corresponding to the return distance of the spindle head 6 on the program tape in advance, since the overshoot distance, that is, the slip distance, can be known empirically for each machine tool. The measuring element 11 and the spindle head 6 can be returned a predetermined distance (k in FIG. 11). Thereafter, the values of the linear scale 12 and slider 13 are read into the memory 78. As a second method of correction, the skip signal is sent to the NC device 85.
Since the data calculation unit 80 calculates the amount of overshoot after receiving the movement, it is also possible to determine how far the machine tool should be returned. For example, it is possible to create a user macro program. In this way, any method can be selected for correcting the slipping distance. After returning the probe 11 along the arrow w in Fig. 11, scale 1
2. Read the value of slider 13. Now work W
To describe the case of measuring the diameter of a hole provided in a hole, the measuring stylus 11 is moved in the direction of arrow a in Fig. 12 and comes into contact with the inner wall on the right side of the figure. Since the spindle head 6 has been moving for a while, the measuring head 11, front lever 41, and rear lever 42
The slider 47 is displaced and generates a voltage. In FIG. 11, the displacement p corresponding to the threshold voltage
When passing the point, a skip signal is sent to the reed relay 74.
The signal is then sent to the NC device 85, and the spindle head 6 is stopped. However, the spindle head 6 slides due to inertia, moves a predetermined distance, and then stops. At the same time, the displacement of the slider 47 after passing the displacement point p corresponding to the threshold voltage is read as a digital signal from the reed relay 72 to the data calculation unit 80, and the finally stopped displacement (digital signal) _M1 is detected. be done. Based on this data _M1 , the data calculation unit 80 moves in the direction of correcting the excess.
A return command is sent to the machine tool, and the spindle head 6 is returned using the second method. As a result, the spindle head 6 stops within the measurement range S, and the displacement M ₂ of the slider 47 at that position is read from the memory 78 into the data calculation circuit 80 . At the same time linear scale 1
2. Read the position L ₁ of the spindle head 6 on the slider 13 from the scale reading device 77 to the data calculation unit 80 via the memory 78 . The amount of return of the spindle head 6 is such that the residual displacement M ₂ a of the slider 47 falls within the measurement range S.
0 will be calculated based on M ₁ and will be commanded to the NC device 85.

Next, in the direction of arrow b in Fig. 12, the measuring element is brought into contact with the opposite side of the hole diameter in the direction a, and the displacement M ₂ b of the slider 47 and the scale coordinate value L ₂ in this case are
is obtained. Therefore, the inner diameter of this hole is D=L−(M ₂ a+M ₂ b)+du.

Here, L=L ₁ −L ₂ and du is a value given as follows. That is, in FIG.
do is the spherical diameter of the measuring head 11, and if the displacements of the measuring head 11 from the neutral point in both directions of the radius of the sphere and until the output of the differential transformer 46 becomes 0 are respectively δ ₁ and δ ₂ , the measurement The apparent diameter of the probe 11 required for this is du=do−(δ ₁ +δ ₂ ).

du can be determined in advance by measuring a hole with a known diameter. Also, by adjusting each part, du≒
It is also possible to set it to 0.

In addition, when determining the hole center position accurately, such as during centering measurement or hole pitch measurement, the center position of the measuring stylus 11 can be determined by rotating the main shaft 15 by 180 degrees during movement in the direction of the arrow b. can absorb the discrepancy. The above-described operation can also be applied to measure the position of the reference plane.

In addition, in FIG. 11, it is also possible to return the measuring stylus 11 excessively to the opposite side and then move it again in the opposite direction to bring it closer to the measurement range. By doing this, for example, when measuring the hole diameter, when the probe 11 comes into contact with the walls on both sides, the positioning direction can be set in the same direction when obtaining the final measurement value (M ₂ a, M ₂ b). Therefore, the positioning accuracy of the machine tool is improved and, as a result, the measurement accuracy is improved.

In FIG. 12, the vertical position of the hole can be measured by rotating and positioning the main shaft 15 by 90 degrees. When the measuring tool 10 is rotated 90 degrees, one of the four light emitters 5
0 is fixed, and the infrared PFM signal is transmitted between them.

The solar cell 49 has a sufficiently large area so that sufficient output can be obtained under normal indoor light, and is charged while the measuring tool 10 is inserted into the magazine 7. If the Ni-Cd battery is frequently used and the Ni-Cd battery is depleted, it is advisable to turn on a light near the spindle head 6 or the magazine 7.

In the above explanation, only the measurement in the direction of the linear scale 12 and slider 13 was explained.
Similarly, it is also possible to measure scales and sliders in other directions, and to correct minute displacements using the same slider displacement.

As explained above, according to the present invention, a measuring tool equipped with a solar cell is provided with a displacement detector that detects minute displacements, and a machine tool is provided that accurately returns the spindle head based on this displacement. Since it is an automatic measuring device, it is possible to significantly reduce the occurrence of measurement errors due to oil films such as lubricating oil present on the slide part, and it is possible to achieve the effect of enabling highly accurate automatic measurement. Furthermore, measurement errors due to running out of battery in the measuring tool can be almost eliminated. Furthermore, since it uses an infrared PFM signal propagation method in the air, cables and other obstructions to machining work are removed, improving machining center work efficiency and eliminating machine malfunctions caused by factory lighting.

[Brief explanation of drawings]

Fig. 1 is an overall side view of a machining center equipped with the automatic measuring device of the present invention, Figs. 2 and 3 are partial longitudinal sectional views of the spindle head, and Figs. 4 and 5 are measuring tools of the present invention. FIGS. 6 and 7 are block diagrams of the transmitting circuit of the present invention, FIG. 8 is a block diagram of the receiving circuit and machine side control device of the present invention, and FIG. 9 is a block diagram of the transmitting circuit of the present invention.
The figure is an overall control block diagram of the automatic measuring device of the present invention, Figures 10 and 11 are graphs for explaining the displacement correction of the present invention, and Figures 12 and 13 illustrate one of the measurement methods. FIG. 6... Spindle head, 10... Measuring tool, 11...
Gauge head, 15... Main shaft, 17... Tool insertion hole, 4
6...Differential transformer (displacement detector), 49...Solar cell, 50...Light emitter, 63...Light receiving section, 65
...F/V converter, 66...A/D converter, 67...Threshold setting circuit, 68...AND
Circuit, 69... Confirmation circuit, 70... Data latch circuit.

Claims (1)

[Scope of Claims] 1. A main spindle rotatably provided on a spindle head and having a tool insertion hole at its tip; a measuring tool that is insertable into the tool insertion hole and has a measuring tip at its tip; A displacement detector installed in a measuring tool and generating an electric signal when the probe comes into contact with an object to be measured; a transmitter that receives a signal from the displacement detector and transmits the signal; and the displacement detector and the transmitter. An automatic measuring device for a machine tool comprising: a solar cell that supplies power to the transmitter; a receiver provided on the spindle head to detect a signal from the transmitter; and a control device that processes the signal from the receiver. 2. The automatic measuring device for a machine tool according to claim 1, wherein the displacement detector is constituted by a differential transformer. 3. The automatic measuring device for a machine tool according to claim 1, wherein the transmitter emits frequency-modulated infrared rays. 4. The automatic measuring device for a machine tool according to claim 1, wherein the transmitter generates a frequency-modulated electromagnetic wave. 5. The automatic measuring device for a machine tool according to claim 1, wherein the control device includes a data processing circuit and a threshold setting circuit.