JPH07190866A - Magnetostrictive torque sensor and measuring device, and cutting tool condition monitoring device using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a magnetostrictive torque sensor having high detection sensitivity and capable of detecting torque generated in two directions orthogonal to each other at the same location. [Configuration] Four square pillar-shaped Adjacent legs 11a and 11b of the core 10 having high magnetic permeability having the legs 11a to 11d.
The first winding 21 is wound around the
Then, the exciting coil 20 is mounted by winding the second winding 22 continuous with the first winding in the opposite direction. In addition, the first winding 31 is wound around the legs 11a and 11d, and the second winding 32 is wound continuously in the opposite direction around the legs 11b and 11c. Coil 3
Wear 0 as well. The sensor is arranged close to the side surface of the rotary shaft 50 so as to face it, and the long sides of both windings of the exciting coil are arranged parallel to the axial direction of the rotary shaft. The core is formed by cutting a cross-shaped groove on one surface of a rectangular parallelepiped block body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostrictive torque sensor and measuring device, and a cutting tool condition monitoring device using them.

[0002]

2. Description of the Related Art A magnetostrictive stress (torque) sensor utilizes a phenomenon in which magnetic permeability changes when mechanical strain is applied to a ferromagnetic material, which is one of magnetostrictive phenomena. The rotating shaft is made of a ferromagnetic material such as iron, and two U-shaped coils (a coil is wound around the open end legs of the U-shaped core to form a bridge so as to face the side surface of the shaft). It is configured to be arranged in a cross shape.

Then, one core is arranged in parallel with the axial direction of the rotating shaft, and the other core is arranged in a direction orthogonal to the axial direction. In other words, the legs of the two cores are located at the vertices of a square, but the sides of the square are located at a 45-degree inclination direction with respect to the axial direction of the rotation axis.

When torque is applied to the rotating shaft in this state, the rotating shaft is twisted to generate tensile stress and compressive stress in the direction of ± 45 degrees with respect to the center line of the shaft, which changes the magnetic permeability of the rotating shaft. To do. This change in permeability is excited by applying an alternating current to one of the two U-shaped coils, and the change in permeability is detected by extracting the signal from the other coil, and based on the detection result, the torque is changed. Is to ask.

[0005]

However, the above-mentioned conventional sensor has the following problems. That is, the magnetic pole portion is the open end of the exciting core, the measured shaft, the open end of the detecting core, the detecting core, the other open end of the detecting core, the measured shaft, the other open end of the exciting core. Has a magnetic path such as. Since the exciting core and the detecting core are arranged in a cross shape, there are two magnetic paths, and the magnetic permeability of each magnetic path is differential with respect to the direction of the torque applied to the shaft to be measured. The torque is detected by changing to.

However, there are four different magnetic paths passing through the measured shaft between the exciting core open end and the detecting core open end. Therefore, it is inevitable that the magnetic permeability of different locations adjacent to each other is measured, and due to the non-uniformity of the magnetic permeability of the shaft to be measured, a large zero point fluctuation occurs due to the shaft rotation.

Moreover, with this method, although the torque in one direction can be detected with high sensitivity, the detection sensitivity with respect to the torque twisted in the opposite direction is low. Therefore, in order to increase the detection sensitivity of the torque in both directions, it is necessary to provide two sensors having the above configuration and dispose them at different positions in the axial direction. Not only becomes more prominent, but also causes an increase in the size of the device.

The magnetic poles formed by the coils are
There is also a problem that the open end face of each core is formed, the magnetic pole area is small, and the sensitivity is low.

The present invention has been made in view of the above background, and its object is to have high detection sensitivity and to detect torque generated in two orthogonal directions at the same location. Further, it is an object of the present invention to provide a magnetostrictive torque sensor and a measuring device capable of performing accurate torque measurement by performing a predetermined correction process even if there is unevenness in the mounting accuracy of each coil or the mounting accuracy of a sensor with respect to a measured object. . Further, by using a torque sensor or the like that achieves the above object, it is possible to accurately detect the torque applied to the cutting tool with a small and simple configuration, whether or not there is a breakage in the cutting tool, prediction of the breakage, and cutting such as wear. It is an object of the present invention to provide a state monitoring device for a cutting tool that can detect the state of the tool.

[0010]

In order to achieve the above-mentioned object, in the magnetostrictive torque sensor according to the present invention, the shape of a figure 8 is formed by the first and second windings wound in opposite directions. The exciting coil formed in the above, a detecting coil having substantially the same shape as that of the exciting coil, and a core having four columnar magnetic cores for mounting the both coils, The direction of arrangement of the second winding and the direction of arrangement of the first and second windings of the detection coil are arranged so as to be orthogonal to each other, and each winding of each coil is arranged among the four magnetic cores. It is wound around a predetermined two adjacent magnetic cores, and the arrangement direction of the two adjacent magnetic cores is made parallel or orthogonal to the axial direction of the rotating body to be measured.

Preferably, when mounting the both coils on the magnetic core, the exciting coil is arranged on the open side of the magnetic core, and at that time, the exciting coil and the detecting coil are arranged on the axis of the magnetic core. It is more preferable to displace them by a predetermined distance along the direction. Furthermore, it is preferable to use the core integrally formed by forming a cross-shaped groove on one surface of a block body having a predetermined shape, because it can be easily manufactured.

As another solution for achieving the above-mentioned object, the first to fourth exciting windings forming the exciting coil are arranged at each apex of the virtual quadrangle, and two adjacent exciting coils are provided. The wires were connected so that currents would flow in the same direction in the windings and currents in the opposite directions would flow in the remaining two excitation windings. And the 1st-4th detection winding which comprises a detection coil so that it may overlap with the said 1st-4th excitation winding was arrange | positioned. Further, the arrangement direction of the pair of excitation windings in which the current flows in the same direction may be parallel or orthogonal to the axial direction of the rotating shaft to be measured.

In such a case, it is more preferable to further include a core having four columnar magnetic cores, and to attach the excitation windings and the detection windings to the magnetic cores.

More preferably, on the premise of the magnetostrictive torque sensor having the various configurations described above, a search coil is further provided so as to measure the total amount of magnetic flux generated by the exciting coil, and the detection coil is output by using the output of the search coil. Is to be able to correct the output of.

Further, in the magnetostrictive torque measuring device according to the present invention, the magnetostrictive torque sensor with a search coil having the above-mentioned structure and the above-mentioned search which is obtained when the rotating body of the torque detection target is rotated without applying torque. Storage means for storing zero point correction value data generated based on the output of the coil and the detection coil, and a zero point stored in the storage means from the output of the search coil when torque is applied to the rotating body. The correction value is read, and the output of the detection coil is corrected based on the read zero point correction value.

Further, in the cutting tool condition monitoring device according to the present invention, the shank portion of the cutting tool that is attached to and detached from the machine tool body or the outside of the spindle that rotates together with the cutting tool has a predetermined relative positional relationship with the axial direction. Arranged magnetostrictive torque sensor or magnetostrictive torque measuring device consisting of any of the above configurations, and the presence or absence of breakage of the cutting tool that is attached to or detached from the machine tool body by receiving the output of the magnetostrictive torque sensor or measuring device, Judgment means for predicting a breakage or a desired state of the cutting tool such as wear, and a predetermined result such as a deceleration command for a drive device to which the cutting tool is mounted, in response to a judgment result of the judgment means. The control signal generating means outputs a control signal.

[0017]

According to the present invention, when a predetermined alternating current is applied to the exciting coil, magnetic flux is generated from one winding of the exciting coil to the other winding of the alternating current. Then, the magnetic flux concentrates on each magnetic core of the core having a small magnetic resistance.
Since the magnetic flux passes through a path having a small magnetic resistance, if no torque is applied to the rotating shaft, the magnetic flux travels straight from one magnetic core to the other magnetic core, that is, in a direction parallel or orthogonal to the axial center. Then, since the exciting coil and the detection coil are arranged orthogonally, the magnetic flux does not cross each winding of the detection coil, and no induced electromotive force is generated on the detection coil side.

On the other hand, if a predetermined torque T is applied to the rotating shaft, stress is applied along the direction of ± 45 degrees with respect to the axial direction. Then, the magnetic permeability of this portion changes due to the inverse magnetostrictive effect. Therefore, since the magnetic flux easily passes through the direction of 45 degrees with respect to the axial direction, the generated magnetic flux travels obliquely and interlinks with each winding of the detection coil, so that an induced electromotive force is generated. The electromotive force increases as the torque increases.

Furthermore, by mounting the excitation and detection coils on a core (magnetic core) made of a material having a high magnetic permeability, the generated magnetic flux is increased even when the number of turns of each winding and the excitation current are small, and when a torque is applied. The interlinkage magnetic flux across each of the coils becomes large. Therefore, the sensor has high sensitivity.

Further, in the inventions of claims 5 and 6, the same is basically the case as described above, and when a predetermined alternating current is applied to the exciting coil when no torque is applied, it is output from one exciting winding pair. The magnetic flux travels straight with respect to the other exciting winding pair adjacent thereto, that is, in the direction parallel or orthogonal to the axis. Then, the magnetic fluxes generated by the respective excitation windings are equal, and therefore the induced electromotive forces generated by the respective detection windings constituting the detection coil are also equal.

On the other hand, if a predetermined torque T is applied to the rotating shaft, stress is applied along the direction of ± 45 ° with respect to the axial direction as described above, and the magnetic flux is directed in the direction of 45 ° with respect to the axial direction. Easy to pass. Therefore, the generated magnetic flux advances obliquely, and the induced electromotive force of the detection winding located in the oblique direction increases. Then, the increased amount increases as the torque increases. Therefore, by monitoring the state of the induced electromotive force of each detection winding, it is possible to know the presence / absence and direction of the torque.

Furthermore, in the magnetostrictive torque sensor and measuring device according to the seventh and eighth aspects, the output of the search coil is constant regardless of the magnitude of the torque. Therefore, the DUT (rotating body) is rotated in a state where a predetermined AC signal is applied to the exciting coil and no torque is applied. Then, the output of the detection coil at that time is caused by variations in characteristics between windings forming each coil, gaps, etc.
It becomes an offset value, that is, a zero point correction value. Furthermore, the output of the detection coil at this time basically corresponds (in principle) to the output of the search coil on a one-to-one basis. Therefore, a table in which both outputs are paired is created and stored in the storage means. Then, at the time of actual measurement in which torque is applied to the rotating body, the outputs of the detection coil and the search coil are simultaneously extracted,
Based on the output of the search coil, the storage means is accessed to read the corresponding zero point correction value. Then, by subtracting the read zero point correction value from the output of the detection coil,
The true output of the detection coil corresponding to the magnitude of torque can be obtained. Then, the torque is calculated from the output (after correction) by a usual method.

Further, in the cutting tool state monitoring device of the present invention, the state of the cutting tool is detected by detecting the torque related to the cutting tool. That is, if the cutting tool falls, the load is removed and the torque sharply decreases. Immediately before it falls, the torque increases. Further, when the tip processed surface of the tool becomes worn, the contact resistance between the tool and the object to be cut increases, so the torque also increases. Therefore, based on the output of the torque sensor,
The current state of the cutting tool is judged, and if necessary, the control signal generating means outputs a predetermined control signal to the driving device of the drill to decelerate the rotation speed and the descending speed, and further stop and reverse rotation. Drive to ensure stable operation.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the magnetostrictive torque sensor according to the present invention will be described in detail below with reference to the accompanying drawings. As shown in FIG. 1, a core 10 having a high magnetic permeability, such as ferrite, having four square pole-shaped magnetic core legs 11a to 11d arranged on the apexes of a square has an exciting coil 20 and a detection coil of the same shape. 30 are arranged so as to overlap with each other with their relative positional relationship shifted by 90 degrees.

The exciting coil 20 includes a first winding 21 and a second winding 21, which are wound in opposite directions by the same number of turns.
The first winding 21 is wound around the legs 11a and 11b, and the second winding 22 is wound around the legs 11c and 11d. As a result, both windings 1
The planar shapes of 1 and 12 are substantially rectangular, and their arrangement directions are parallel. As a result, the exciting coil 20
When a current is made to flow from the first winding 21 side, a current will flow in each winding in the direction shown in FIG.

Similarly, the detection coil 30 includes a first winding 31 configured to be wound around the legs 11a and 11d of the core 10 by a predetermined number of turns, and the first winding 31 of the first winding 31. The second winding 32 is formed by winding a predetermined number of turns around the legs 11b and 11c in the opposite direction to the winding direction. And these both windings 31, 32
Also, the plane shape is substantially rectangular and the arrangement directions are parallel.

As a result, the arrangement direction of the excitation coil 20 and the arrangement direction of the detection coil 30 are orthogonal to each other. The coils 20 and 30 are each formed by winding one wire in a predetermined direction. In addition, as a method of forming each winding, after winding one winding (for example, the first windings 21 and 31) a predetermined number of times, the other winding (for example, the second windings 22 and 32) is wound. The same winding number may be applied in the opposite direction, or both windings may be alternately wound, and the winding method is arbitrary.

Further, in this example, the exciting coil 20 is arranged on the open side of the legs 11a to 11d, and the exciting coil 20 is positioned on the open side tip. On the other hand, the detection coil 30 is located on the base side of the legs 11a to 11d.
As a result, the distance between the legs of the coils 20 and 30 in the axial direction is increased. Note that the present invention does not necessarily have to be arranged in such an order, but the reverse (the detection coil 30 is connected to the leg portions 11a to
11d) (disposed on the open side of 11d), or in any arrangement, both coils 20 and 30 may be arranged close to each other.

In order to manufacture the core 10 having the above predetermined shape, a rectangular parallelepiped block body is manufactured, and then,
It can be easily formed by cutting one surface and cutting a groove in a cross shape.

Further, in order to mount the sensor having such a structure, as shown in FIG. 2, the rotary shaft 50 made of a magnetic material.
Of the windings 21 and 22 of the exciting coil 20.
Both windings 31 and 3 of the detection coil 30 are orthogonal to the axial direction of 0.
The long side of 2 is arranged so that the arrangement direction of the long side is parallel to the axial direction of the rotating shaft 50. The positional relationship of this arrangement may be reversed (the arrangement direction of the long sides of both windings 21 and 22 of the exciting coil 20 is parallel to the axial direction of the rotary shaft 50).

Then, as shown in FIG. 3, the exciting coil 2
0 is connected to an AC power supply 51 so that an AC signal (excitation current) can be supplied. Further, the detection coil 30 is
A synchronous rectifier 52 is connected between both terminals so that the output voltage can be detected.

Here, the principle of detection (operation) of the torque sensor will be described. First, when a predetermined alternating current is passed through the exciting coil 20 using the alternating current power source 51,
One winding of the exciting coil 20 (for example, the first winding 21)
Magnetic flux is generated from the other winding toward the other winding (for example, the second winding 22). Then, the magnetic flux concentrates on each of the legs 11a to 11d of the core 10 having a small magnetic resistance.

At this time, in the magnetic field generated by the current flowing in the exciting coil 20, the magnetic flux flows through a path having a low magnetic resistance, so that it is assumed that no torque is applied to the rotary shaft 50, and at a certain time, as shown in FIG. As shown in A), the leg 1
The magnetic flux emitted from 1a passes through the rotary shaft 50 having a small magnetic resistance, and moves along the axial direction of the rotary shaft 50 so as to enter the leg portion 11d having a short distance. Similarly, the legs 11b
The magnetic flux emitted from the inside of the rotary shaft 50 moves along the axial direction and enters the leg portion 11c. Although not shown, since the exciting current supplied to the exciting coil 20 is an AC signal, when the flowing direction of the current is reversed, the magnetic flux direction is also reversed.

Since both of these magnetic fluxes do not traverse the windings 31 and 32 of the detection coil 30, respectively,
No induced electromotive force is generated on the detection coil 30 side. Therefore, the output of the synchronous rectifier 52 also becomes zero.

On the other hand, as shown in FIG.
When a predetermined torque T is applied to 0, stress (indicated by a double-headed arrow in the ± σ diagram) is applied along the direction of ± 45 degrees with respect to the axial direction. Then, the magnetic permeability of this portion changes due to the inverse magnetostrictive effect. The change in the magnetic permeability increases as the torque increases, and the magnetic permeability in the tension direction (+ σ direction) increases when the magnetostriction constant of the shaft is positive. Therefore, since the magnetic flux easily passes in the lower left direction as shown by the arrow in the figure, the generated magnetic flux links with the windings 31 and 32 of the detection coil 30 and an induced electromotive force is generated. The electromotive force increases as the torque increases. Therefore, the magnitude of the torque can be detected by measuring the electromotive force generated at both ends of the detection coil 30.

Moreover, the torque in the opposite direction to that shown in the drawing is applied to the rotary shaft 5.
When it reaches 0, the magnetic flux tends to flow in the upper right direction contrary to the illustration. Therefore, the phase of the flux linkage is reversed,
By detecting the phase by the synchronous rectifier 52,
The direction of the torque applied to the rotary shaft 50 can also be detected.

In this example, the excitation / detection coil 2
0 and 30 are cores 10 (leg parts 1) made of a material having high magnetic permeability.
1a to 11d), the generated magnetic flux can be increased even when the number of turns of each winding and the exciting current are small, and the interlinkage magnetic flux across the coils 20 and 30 when torque is applied is increased. . Therefore, the sensor has high sensitivity.

Further, in this example, since the exciting coil 20 is arranged at the open end of each leg 11a to 11d, the distance from the outer peripheral surface of the rotary shaft 50 can be shortened, and as a result, the leakage magnetic flux is small. The magnetic flux generated by the excitation current is effective for torque detection (efficiently)
It can be used and the sensitivity is improved.

Further, the exciting coil 20 and the detecting coil 30
The relationship with can be expressed by the equivalent circuit shown in FIG.
A line-to-line capacitance is generated between the coils 20 and 30 due to capacitive coupling. When the line capacitance increases, a leak current flows from the exciting coil 20 side to the detecting coil 30 side, wasting power consumption, and the efficiency of converting the exciting current into magnetic flux decreases. However, in this example, as described above, the excitation coil 20 and the detection coil 30 are connected to each leg portion 1.
Since the electrodes 1a to 11d are arranged apart from each other by a predetermined distance along the axial direction, the line capacitance can be reduced, the conversion efficiency of the exciting current to the magnetic flux can be improved, and the magnetic flux crossing the detection coil 30 can be increased. It can be efficiently converted into a voltage, and the detection sensitivity can be further improved and the loss can be reduced.

Furthermore, the non-grooved substrate portion 12 (see FIG. 1, etc.) which is continuous with the four leg portions 11a to 11d functions as a yoke, which also suppresses the generation of leakage magnetic flux. However, the detection sensitivity is improved.

In the above-mentioned embodiment, the core 10 is formed by cutting the cross-shaped groove of a rectangular parallelepiped block body made of a material having a high magnetic permeability such as ferrite, but the present invention is not limited to this. Without any, as shown in FIG.
A core 10 in which the four legs 11a to 11d are cylindrical
However, the shape is arbitrary. In this case, although not specifically shown, the planar shape of each winding corresponds to the outer peripheral surface of the leg portions 11a to 11d and is substantially elliptical.
Also, in the manufacturing process, a predetermined mold may be formed in advance and the mold may be used instead of cutting the leg portion having a predetermined shape, and the manufacturing process is arbitrary.

Further, as shown in FIG. 7, the leg portion 11a
11d and the substrate 13 for mounting them may be separately formed, and they may be bonded and integrated. In this case, at least the legs 11a to 11d are made of a material having a high magnetic permeability, but if the substrate 13 is made of a material having a high magnetic permeability (which may be the same as or different from the material of the legs), as described above. Demonstrate the function of the yoke.

Furthermore, as shown in FIG.
R may be attached so that the open side end surface 11 ′ of each leg 11 is along the outer peripheral surface of the rotary shaft 50. With such a configuration, the leakage magnetic flux emitted from the open side end face 11 'can be suppressed as much as possible, and the sensitivity of the sensor can be further improved.

Furthermore, in the above-mentioned embodiment and modification, the leg portion 11 as a magnetic core is relatively long, and both coils 2
The coils 0 and 30 are separated by a predetermined distance in the axial direction, and the planar shape of each winding is rectangular and oval. However, as shown in FIG. 9A, the core 10 has a planar shape with a central angle of 90 degrees. It may be a flat shape having four fan-shaped legs 11a to 11d and a short protruding length.

Then, as shown in FIG. 6B, the exciting coil 20 is provided with semi-circular first and second windings 21 and 22. Straight part 21
The coils a and 22a are arranged so as to coincide with each other on the same line (may be arranged parallel to each other in a close state), and the windings 21 and 22 are arranged to form one circle. The windings 21 and 22 are formed by winding a single wire in a semicircular shape by a predetermined number of turns, and in the final arrangement state, the windings 21 and 22 have the same turns in opposite directions. It will be wound by the number of times. Then, the first winding 21
Is wound around the legs 11a and 11b, and the second winding 2
2 is wound around the legs 11c and 11d.

Similarly, the detection coil 30 includes cores 11a,
A first winding 31 configured to be wound a predetermined number of turns around 11d and a second winding 31 configured to be wound a predetermined number of turns around the leg portions 11b and 11c.
Windings 32 of the first and second windings 31, 3
The two straight line portions 31a and 32a are arranged so as to coincide with each other on the same line (may be arranged in parallel in a close state).

As a result, the linear portion 21 of the exciting coil 20 is
a, 22a and the linear portions 31a, 33a of the detection coil 30.
Are orthogonally arranged, and the coils 20 and 30 are arranged at positions displaced by 90 degrees.

According to this structure, since both coils 20 and 30 are arranged close to each other, the above-described leakage magnetic flux has an effect, but the height is suppressed and the size is reduced. Further, the magnetic pole area with respect to the outer peripheral shape (length) increases. In addition, when the influence of the leakage magnetic flux is large, the lengths of the leg portions 11a to 11d may be appropriately extended. Note that the other configurations and effects are the same as those of the above-described embodiment, and thus the description thereof will be omitted.

FIG. 10 shows a second embodiment of the magnetostrictive torque sensor according to the present invention. As shown in the figure, four columnar magnetic core legs 1 arranged on the vertices of a square.
An exciting coil 20 and a detecting coil 30 are arranged in a predetermined positional relationship on a core 10 having a high magnetic permeability such as ferrite having 1a to 11d.

In the present embodiment, each leg 11a-1
The first method is to wind each coil 20, 30 around 1d.
This is different from the embodiment. That is, the exciting coil 20 is
The first to fourth exciting windings 23a to 23d having the same number of turns are wound around the leg portions 11a to 11d, respectively, and the windings 23a to 23d are connected in a predetermined order to form one continuous electric wire. There is. Specifically, as shown in FIG. 11, when a current is applied to the one electric wire, the first and second excitation windings 23a and 23b mounted on the two adjacent leg portions 11a and 11b are Current flows in the same direction (clockwise in this example), and the other two adjacent leg portions 1
3rd and 4th exciting windings 23c mounted on 1c and 11d,
Reference numeral 23d appropriately connects the excitation windings 23a to 23d so that a current flows in the opposite direction (counterclockwise in this example).

As a result, by connecting both ends of one continuous line to the AC power source 40 as shown in the figure, at a certain moment, the current flows as described above, and the leg portions 11a to 11d have a predetermined current. Magnetic flux is generated in the direction.
Since it is an alternating current, at a different moment, a current flows in the opposite direction to that shown in FIG. 11, and the generated magnetic flux also becomes in the opposite direction.

The method of connecting the windings to each other is not limited to the above-described embodiment. In short, the current flows in the two adjacent exciting windings in the same direction, and the remaining two exciting windings are connected. The current may flow in the opposite direction to the line. Further, in order to actually attach the coils (windings) to the leg portions 11a to 11d, one long wire is used, and the exciting coil 20 and the detection coil 30 are wound around the leg portions in order in a predetermined direction. Each winding may be separately wound around each leg and the ends of each winding may be appropriately connected to each other to form the exciting coil 20 and the detecting coil 30.
May be formed respectively. Especially according to the latter method,
The winding process becomes very easy.

On the other hand, the detection coil 30 is also the excitation coil 2 described above.
Like each winding constituting 0, the first to fourth detection windings 3 each having the same number of turns in each leg 11a to 11d.
3a to 33d are wound and formed. As a result, in each of the detection windings 33a to 33d, an induced electromotive force is generated by the magnetic flux generated by the current flowing in the corresponding excitation windings 23a to 23d (see FIG. 12). And
The respective detection windings 33 a to 33 d are connected to the torque detection device 45.

This torque detecting device 45, as shown in FIG. 13, has a first detecting winding 33a and a fourth detecting winding 33d.
Connected to the first adder 45a, and the induced electromotive force of the second detection winding 33b and the third detection winding 33c
It is connected to the adder 45b, and both adders 45a and 45b are further connected.
Is connected to the subtractor 45c.

Further, in this example, the exciting coil 20 is arranged on the open side of the legs 11a to 11d, and the exciting coil 20 is located at the open end, and the detection coil 30 is located on the legs 11a to 11d. It is located on the root side. As a result, the distance between the legs of both coils 20, 30 in the axial direction is increased.

To mount the sensor having such a structure, as shown in FIG. 14, the rotary shaft 5 made of a magnetic material is used.
The magnetic fluxes generated from the exciting coil 20 are arranged so as to be parallel or orthogonal to the axial direction of the rotary shaft 50 at this time. That is, core 1
The virtual squares formed by connecting the leg portions 11a to 11d of 0 are arranged so that each side (a line connecting the adjacent leg portions) is parallel or orthogonal to the axial direction. In this example, the generated magnetic flux is arranged so as to pass in parallel.

Here, the principle of detection (operation) of the torque sensor will be described. First, when a predetermined AC current is passed through the exciting coil 20 using the AC power supply 40, the
From the pair of exciting windings (for example, the first and second exciting windings 23a and 23b) that are the same as the energization direction of the exciting coil 20, to the other exciting winding (for example, the third and fourth exciting windings 23c and 23c).
A magnetic flux is generated toward d). Then, the magnetic flux concentrates on each of the legs 11a to 11d of the core 10 having a small magnetic resistance.

At this time, the magnetic field generated by the current flowing through the exciting coil 20 is a magnetic flux flowing through a path having a low magnetic resistance, so that it is assumed that no torque is applied to the rotating shaft 50 at a certain time. As shown in A), the magnetic flux emitted from the leg portion 11a passes through the rotary shaft 50 having a small magnetic resistance and moves along the axial direction of the rotary shaft 50 to enter the leg portion 11c having a short distance. . Similarly, the legs 11
The magnetic flux emitted from b moves in the rotating shaft 50 along the axial direction and enters the leg portion 11d. Although not shown, since the exciting current supplied to the exciting coil 20 is an AC signal,
When the direction of the current flow is reversed, the direction of the magnetic flux is also reversed.

Then, the induced electromotive voltages V1 to V4 generated in the respective detection windings 33a to 33d are V1 = V2 = V3 = V4.
(Because of the same number of turns), the output of the first adder 45a is V1 + V4 and the output of the second adder 45b is V2 + V3, both of which have the same value. Therefore, the output of the subtractor 45c becomes zero.

On the other hand, as shown in FIG.
When a predetermined torque T is applied to 0, stress (indicated by a double-headed arrow in the ± σ diagram) is applied along the direction of ± 45 degrees with respect to the axial direction. Then, the magnetic permeability of this portion changes due to the inverse magnetostrictive effect. The change in the magnetic permeability increases as the torque increases, and the magnetic permeability in the tension direction (+ σ direction) increases when the magnetostriction constant of the shaft is positive.

Therefore, the magnetic flux is, as shown by the arrow in the figure,
Since it becomes easier to pass in the lower right direction, the magnetic flux that crosses the first and fourth detection windings 33a and 33d increases, and V1 and V4 increase. Therefore, the output of the subtractor 45c ((V1 + V
4)-(V2 + V3)) becomes positive. Further, the magnitude thereof increases as the torque increases. Therefore, the subtractor 45
By detecting the presence / absence of the output voltage of c, the presence / absence of torque can be detected, and the magnitude of the torque can be detected from the voltage value.

Moreover, the torque in the opposite direction to that shown in the drawing is applied to the rotary shaft 5.
When 0 is applied, the magnetic flux tends to flow in the upper left direction contrary to the illustration. Therefore, in the above example, the voltage values of V2 and V3 become large, and the output of the subtractor 45c becomes negative. Therefore, the direction of the torque applied to the rotary shaft 50 can also be detected.

The detection of the output voltage according to the torque of the detection coil is not limited to the above-mentioned embodiment,
For example, as shown in FIG. 16, each of the detection windings 33a to 33d
May be connected in a predetermined order to form one continuous wiring, so that the voltage Vout (having the same meaning as the output of the subtractor) at both ends thereof may be detected (equivalent circuit at that time). Is as shown in FIG. 17). In such a case, it is sufficient to simply connect the wires, which simplifies the configuration.

Further, in the torque detecting device 45 of the above-mentioned embodiment and the wiring system shown in FIG. 16, both are installed so that Vout = (V1 + V4)-(V2 + V3), but the present invention is not limited to this. Instead, for example, Vout = (V1-V2) + (V4-V3) or Vout = (V1-V3) + (V4-V2) may be installed. In addition, the shape of the core is not limited to the above-described embodiment, and the shape of the leg portion (magnetic core) is a square pole, or the leg portion and the substrate for connecting the leg portion are formed as separate members, and the connection is integrated. (For example, the structure shown in FIG. 7) may be used. Further, as shown in FIG. 8, the tip of the leg is rounded to match the circumference of the rotating body, or as a flat core as shown in FIG. However, the shape is arbitrary.

In the above embodiment, the number of turns of the excitation winding and the number of turns of the detection winding are the same for each winding, but the present invention is not limited to this, and the point is that the detection coil side when the torque is zero. It suffices if the output of is adjusted to zero.

Although not shown in the drawings, in the present invention, the core (magnetic core) does not necessarily have to be provided as in the above embodiment. That is, an air core coil may be used. As a result, the thickness is almost eliminated, and the torque sensor becomes a microminiature. In practice, in order to maintain the positional relationship between the windings of each coil, for example, the windings are formed on both sides of one film sheet or on a plurality of film sheets, and the films are predetermined as necessary. It is configured by stacking in the positional relationship of. And
If the film sheet is formed of a flexible member, the film can be curved to an arbitrary radius of curvature and can be arranged in proximity to the rotation axis of the detection target. The other configurations and effects are the same as those of the above-described first embodiment and modifications thereof, and therefore description thereof will be omitted.

FIG. 18 shows a magnetostrictive torque sensor according to a third embodiment of the present invention. This embodiment is based on the above-described first embodiment, and further improves / improves the detection accuracy. That is, in each of the above-mentioned embodiments and modified examples, ideally, the output of the detection coil is zero when the torque is zero, but in reality, the balance between the windings is caused by an error in mounting / winding the windings. Is not taken, or because the gap between the tip of each leg of the core and the surface of the rotating shaft is not constant due to problems in mounting accuracy when the magnetostrictive torque sensor is placed facing the rotating shaft, Even when the voltage is not applied, there is a magnetic flux that crosses the detection coil, and an output voltage may be generated in the detection coil.

Therefore, in the present embodiment, in addition to the exciting coil 20 and the detecting coil 30, a search coil 60 is mounted around the leg portions 11a to 11d of the core 10 in a predetermined manner.
The total amount of magnetic flux generated by is measured, and a predetermined correction process is performed based on the measured total amount.

This counter-coil coil 60 is composed of two counter-coil windings 61 and 62, and the first and second counter-coil coils 61 and 62 constitute the exciting coil 20 as shown in FIGS. 2 corresponding 2 as well as windings 21 and 22
It is wound around the legs of a book and formed into a figure 8 shape as a whole.

Further, as another winding method of the search coil 60, for example, as shown in FIG. 20, each leg portion 11a to 11d of the core 10 is similar to the idea of each winding in the second embodiment.
The windings 23a to 23d may be wound around each of them, and they may be appropriately connected in series.
The order of connecting in series is the search coil 60.
The amount of magnetic flux traversing the shaft is not affected by the amount of torque applied to the shaft, but is affected only by the gap between the tips of the legs 11a to 11d and the rotary shaft 50. That is, the winding may be performed so as to detect the total amount of magnetic flux generated by the exciting coil 20. In addition, the sensor (core 10) for the rotating shaft 50
Since various basic configurations such as the relative positions of the above and the principle of torque detection are the same as those of the above-described first embodiment, the description thereof will be omitted.

FIG. 21 shows an embodiment of the magnetostrictive torque measuring device according to the present invention. That is, FIGS.
Each coil 20, 30, 60 in the magnetostrictive torque sensor with the search coil 60 shown in FIG. 0 has an equivalent circuit as shown in FIG. Then, the sine wave generation circuit 7
When an output of 0 is applied to the exciting coil 20 and an AC signal is applied, an induction force corresponding to the total amount of magnetic flux generated by the exciting coil 20 is applied to both ends of the search coil 60 regardless of the magnitude of the torque applied to the rotating shaft. Electricity is generated. On the other hand, an induced electromotive force corresponding to the magnitude of the torque applied to the rotating shaft is generated at both ends of the detection coil 30. Further, for the reason described above, the detection coil 3 is used even when no torque is applied.
A predetermined induced electromotive force is generated at 0.

Therefore, in this example, the outputs of the search coil 60 and the detection coil 30 are input to the multipliers 71a and 71b, respectively, and are multiplied by the outputs of the sine wave generating circuit 70, and then the low-pass filters 72a and 72b are connected. By passing it, synchronous detection is performed and a DC output is obtained. Then, the DC output is converted into an A / D converter 73
After being converted into a digital value by being input to each of a and 73b, it is input to the CPU 74, and based on both data (output of the detection coil 30 and the search coil 60) given by the CPU 74 and the correction data stored in the RAM 75. The true output corresponding to the normal magnitude of the torque (which is not affected by the gap variation or the like) is obtained.

The specific processing function of the CPU 74 is the correction table (FIG. 23) stored in the RAM 75 shown in FIG.
24) and a correction function at the time of actual torque measurement shown in FIG. 24.

First, the correction table generating function will be described. A predetermined alternating current is applied to the exciting coil 20 and the rotary shaft 50 is rotated without applying torque to the rotary shaft 50 (ST1). In this state, the synchronously detected output of the search coil 60 and the synchronously detected output of the detection coil 30 are read (ST2, ST3). A table in which the output of the search coil 60 and the output of the detection coil 30 read at the same timing is paired is created and stored in the RAM 75 (ST4, ST5). The output of the detection coil when the torque is zero is caused by a gap or other imbalance in the balance and can be regarded as constant regardless of the value of the torque, so that the value can be regarded as an offset value. Therefore, as also shown in FIG. 23, the output of the detection coil 30 is stored as a zero point correction value. Then, the above processing is performed until the rotation of the rotary shaft is stopped (ST6).

Further, at the time of actual torque measurement, a predetermined AC current is applied to the exciting coil 20 and the search coil 60 and the detection coil 30 in a state where torque is applied to the rotating shaft.
Is read (ST11, ST12). Then, based on the read output of the search coil 60, the RAM 75
The corresponding zero point correction value is acquired by referring to the table stored in (ST13).

Then, the zero point correction value is subtracted from the output of the detection coil 30 (ST14). This eliminates fluctuations in the detection coil output due to factors other than torque,
A true output corresponding to the torque applied to the rotary shaft 50 is obtained. Then, the calculation result is output and the correction detection process is ended (ST15).

Although the output device of the torque value (corrected) obtained by the CPU 74 is not shown in FIG. 21, various output devices such as a display device such as a display, a printer and a voice output device are actually used. Can be used.

It should be noted that the search coil output and the detection coil output should correspond one-to-one, but the output of the detection coil corresponding to the output of the same search coil due to measurement error, error in A / D conversion, or the like. May occur more than once. However, even if multiple values occur, these values are approximate, so any value (for example, the center value) among them, or the value obtained by performing a predetermined numerical calculation process such as the average value is corrected to the zero point. It can be handled by setting the value.

Further, in the above-described embodiment, an example in which the search coil is mounted at a predetermined position of the first embodiment is basically described, but the present invention is not limited to this, and the first embodiment is not limited to this. The present invention can be applied to the modified example and the magnetostrictive torque sensor having various configurations shown in the second embodiment.

FIG. 25 shows an embodiment of the cutting tool condition monitoring apparatus according to the present invention. As shown in the figure, in this example, a drill for drilling is used as a cutting tool that is detachably attached to a machine tool. That is,
The drill 80 is gripped by the chuck 81a of the machine tool main body 81, rotates by receiving the rotational force of the drive motor built in the machine tool main body 81, and cuts the work (workpiece) 82 arranged at the lower end. It is designed to be processed to make a predetermined hole.

Then, at a predetermined position of the drill 80, a mounting jig 85 incorporating the magnetostrictive torque sensor 84 having the structure described in each of the above-described embodiments is set. By this mounting jig 85, the torque sensor 84 is arranged to face the outer peripheral surface of the drill 80 in a non-contact manner. Further, at the time of this attachment, it should not interfere with the rotation and the vertical movement of the drill 80. The torque sensor 84 may be moved up and down by following up and down movements of the drill 80.
Is preferably fixed in the direction of rotation.

The specific mounting position of the sensor 84 is as shown in FIG. As shown, the drill 80 is composed of a blade portion 80a and a shank (handle portion) 80b in which no groove is formed. It should be noted that various cutting tools other than a drill have a grindstone or other processing member instead of the blade portion, and the shank is arranged at the base end side, which is common in flow rotation.

And the shank 80b of the drill 80
A torque sensor 84 is arranged opposite to the outside of the portion. At this time, the open side of the leg portion 11 of the core 10 is close to the outer peripheral surface of the shank 80b, and moreover, the arrangement direction of the exciting coil 20 and the detection coil 30 mounted on the leg portion 11 is parallel to the axial direction of the drill 80 or Arrange them so that they are orthogonal. It should be noted that this specific arrangement is the same as in the above-described embodiments and modifications of the sensor, and the illustrated rotating shaft 50 may be replaced with a shank 80b.

Then, as shown in FIG. 27, the exciting coil 20 is connected to the AC power source 90, and the detecting coil 30 is connected to the synchronous rectifier 91. Then, according to the above-described operating principle of the torque sensor, when an AC signal is applied to the exciting coil 20 by the AC power source 90 under a torque, an induction voltage is induced on the detection coil 30 side by electromagnetic induction, and a predetermined AC voltage is applied. The signal is output. It should be noted that the outputs of the detection coil 30 and the synchronous rectifier 91 are zero when there is no load (no torque is applied). Although not shown in FIG. 25, an AC signal is applied to the exciting coil 20 from the outside of the torque sensor 84 in the mounting jig 85.

Further, as shown in FIG. 25, the output of the torque sensor 84 (output of the synchronous rectifier 91) is sent to the control circuit 87 which is the control signal generating means through the comparator 86 which is the determining means. The control circuit 87 is configured to perform feedback control or the like on the machine tool main body 81 based on the output (L / H) of the comparator 86, or to perform a predetermined display or the like.

That is, in the case of the cutting process for making a hole in the work 82, the change of the torque with respect to the change of the time t is normal as shown in FIG. 28A and abnormal (broken).
In that case, it becomes as shown in FIG. Therefore, the torque (sensor output) that cannot be obtained if normal is set as the threshold value in the reference voltage of the comparator 86. Then,
If it is normal, the output is L because the reference voltage is always higher, but in the case of breakage, the output of the comparator 86 changes to H because the sensor output exceeds the threshold value in the middle.

In the control circuit 87, an abnormality is output to a display device 88 such as a display, a lamp (warning, etc.) is turned on, or a voice is output via a voice output unit 89. At the same time, an abnormal signal is issued to the machine tool body 81. Based on the abnormal signal, the machine tool main body 81 lowers the output of the drive motor or stops or reversely drives it to perform a predetermined process such as pulling up the drill.

29 and 30 show another embodiment of the cutting tool condition monitoring apparatus. In the embodiment shown in FIG. 25, the ON / OFF binary control is used, but in this embodiment, continuous control is possible with respect to the magnitude of the torque. That is, as shown in FIG. 29, the machine tool body is
A spindle motor 92 for rotating the drill 80 forward and backward,
A feed motor 93 for moving the drill 80 up and down is provided, and the rotations of both motors 92, 93 are controlled by drivers 95, 96 receiving a speed command from the cutting control device 94. As a result, the spindle motor 9
In 2 the cutting (drilling) processing is performed by operating the feed motor 93 while moving the drill 80 forward at a predetermined speed and moving the drill 80 downward to bring it into contact with the work 82 at a predetermined pressure. Become.

At this time, if the rotation output of the feed motor 93 is increased, the machining time is shortened, but the reaction force received by the drill 80 from the work 82 is strong and a large torque is applied, which may cause breakage, and conversely the feed motor 93. If the output of the drill 80 is reduced, the risk of breakage of the drill 80 is reduced as much as possible, but the processing time is extended. That is, when the rotation speed of the drill 80 is constant, the torque applied to the drill depends on the feed amount (down speed).

Therefore, in this example, the torque sensor 84 according to the present invention is provided outside the shank portion of the drill 80 (see FIG. 2).
5 to 27), the output of the torque sensor 84 is sent to the cutting control device 94, and the drill 8 is controlled by feedback control.
The cutting process is performed in such a state that the torque above 0 is not applied to a certain value.

That is, as shown in FIG. 30, the cutting control device 94 includes a PID controller 94a as a judging means,
The PID controller 9 is composed of a feed speed calculation unit 94b as a control signal generation unit and a spindle rotation control unit 94c.
The difference between the signal based on the torque applied to the drill 80 detected by the torque sensor 84 and the signal based on the set load is input to 4a. Here, the set load is a value with a predetermined margin for the torque that breaks the drill 80. The spindle rotation control section 94c issues a control signal to the spindle motor driver 95 to rotate the spindle motor 92 at a constant speed.

In this state, the PID controller 94a determines the descending speed of the drill 80, that is, the feed amount from the positive / negative of the input signal and its absolute value. In other words, when the input signal is negative, the torque applied to the drill 80 exceeds the set load and there is a high risk of breakage, so it is necessary to reduce the feed amount or revert (raise the drill). On the other hand, when the input signal is positive, the torque applied to the drill 80 is smaller than the set load, so even if the torque applied to the drill 80 is increased a little, the drill is unlikely to break. Increase processing efficiency by increasing the number. Then, the increase / decrease amount is PI
It is determined by the absolute value of the input signal to the D controller 94a. Then, the determined feed amount is sent to the next-stage feed speed calculation unit 94b, the speed of the feed motor 93 required to obtain the feed amount is obtained, and the decided speed is output to the motor driver 96 as a control signal.

With such a structure, the torque (load) applied to the drill 80 during cutting can be kept below the breakage level. Further, since the drill is not unduly loaded, the life of the drill can be extended. Also, by detecting the torque value, it is possible to know the degree of wear of the drill, and it becomes easy to set a reference for replacement.

Further, in each of the above-described embodiments, an example in which a drill is used as a cutting tool has been described, but the present invention is not limited to this, and it is possible to use a grindstone other than a drill and one of various types. it can. In other words, as a machine tool using such a cutting tool, there is a machine tool that performs various machining with a rotating cutting tool such as a drill, a milling machine, a drilling machine or a honing machine.

Further, in each of the above-described embodiments, the torque sensor is arranged opposite to the shank of the cutting tool so as to directly measure the torque applied to the cutting tool. As shown, chuck 81
A main shaft 96 for transmitting the rotational force of the drive motor is provided at the upper end of a. This spindle 96 and chuck 81
a Furthermore, the drill 80 (cutting tool) integrally rotates and moves. Therefore, the torque applied to the drill 80 is
It will be added to the main shaft 96 as it is. Therefore, the magnetostrictive torque sensor of the present invention may be arranged at a predetermined position outside the main shaft 96 while maintaining a predetermined relative positional relationship.

[0096]

As described above, in the magnetostrictive torque sensor according to the present invention (claims 1 to 4), when the torque is not applied to the rotating shaft, there is no output on the detection coil side and the torque is applied. And an output corresponding to the magnitude of the torque is generated on the detection coil side. Moreover, the phase of the output signal generated on the detection coil side with respect to the AC signal applied to the excitation coil side differs depending on the torque direction. Therefore, the torque generated in two orthogonal directions at the same location can be detected by measuring the magnitude of the output (including the presence or absence) and its phase. Moreover, the area of each magnetic pole is almost half of the entire sensor (coil) and each coil is wound around the magnetic core, so that the detection sensitivity is improved.

Further, in the magnetostrictive torque sensor according to the fifth and sixth aspects, similarly to the above, when no torque is applied to the rotary shaft, the induced electromotive forces generated in the detection windings become substantially equal to each other, and As a result, the induced electromotive force of the detection windings located on one diagonal line increases according to the magnitude of the torque. Therefore, the torque generated in two orthogonal directions at the same location can be detected by measuring the magnitude of the output (including the presence or absence) and its phase. Moreover, since the area of each magnetic pole is almost the entire surface of the sensor (coil), the detection sensitivity is improved. When each winding is wound around the magnetic core, the torque sensor has higher sensitivity.

Further, in the magnetostrictive torque sensor and the torque measuring device according to the seventh and eighth aspects, the zero point correction is performed by using the output of the search coil, and the output corresponding to the true torque applied to the measuring object is obtained. Obtainable. As a result, accurate torque measurement can be performed by performing the above-described predetermined correction process even if there is unevenness in the mounting accuracy of each coil or the mounting accuracy of the sensor with respect to the measured object.

Furthermore, in the cutting tool condition monitoring device according to the present invention (claim 9), since the torque applied to the cutting tool can be detected with a non-contact and simple structure, the magnitude and change of the torque can be detected. It is possible to determine whether or not there is a breakage, determine whether there is a high possibility of breakage, and detect the state of the cutting tool such as chipping or wear of the blade, based on the degree of. Further, since it is detected magnetically, it is less likely to be affected by the environment at the time of cutting and can be detected regardless of the diameter of the cutting tool.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a magnetostrictive torque sensor according to the present invention.

FIG. 2 is a diagram showing a usage state of the embodiment shown in FIG.

FIG. 3 is a diagram showing a measurement system.

FIG. 4 is a diagram illustrating an operation principle.

5 is a diagram showing an equivalent circuit of the embodiment shown in FIG.

FIG. 6 is a diagram showing a modified example.

FIG. 7 is a diagram showing another modification.

FIG. 8 is a diagram showing still another modified example.

FIG. 9 is a diagram showing still another modified example.

FIG. 10 is a diagram showing another embodiment of the magnetostrictive torque sensor according to the present invention.

FIG. 11 is a diagram showing an example of a method of connecting exciting coils.

FIG. 12 is a diagram showing an example of a detection coil.

FIG. 13 is a diagram showing an example of torque detection means.

FIG. 14 is a diagram showing an example of a usage mode.

FIG. 15 is a diagram illustrating an operation.

FIG. 16 is a diagram showing an example of another torque detection means.

FIG. 17 is an equivalent circuit diagram for the connection of each winding shown in FIG.

FIG. 18 is a diagram showing still another embodiment of the magnetostrictive torque sensor according to the present invention.

FIG. 19 is a diagram showing a winding state of each coil of the torque sensor shown in FIG. 18.

FIG. 20 is a diagram showing an example of a winding method of the search coil different from that in FIG. 18;

FIG. 21 is a diagram showing an example of a magnetostrictive torque measuring device according to the present invention.

FIG. 22 is a flowchart showing a part of the function of the CPU as a correction means.

FIG. 23 is a diagram showing an example of a table stored in a RAM.

FIG. 24 is a flowchart showing a part of the function of the CPU as a correction means.

FIG. 25 is a diagram showing an embodiment of a cutting tool condition monitoring device according to the present invention.

FIG. 26 is a diagram showing a mounting position of a magnetostrictive mounting sensor with respect to a cutting tool.

FIG. 27 is a diagram showing a mounting position of a magnetostrictive mounting sensor with respect to a cutting tool.

FIG. 28 is a diagram illustrating the operating principle of the control device shown in FIG. 25.

FIG. 29 is a diagram showing another embodiment of the cutting tool condition monitoring device according to the present invention.

FIG. 30 is a diagram showing a main part of the control device shown in FIG. 29.

[Explanation of symbols]

 10 cores 11 and 11a to 11d leg (magnetic core) 20 excitation coil 21 first winding 22 second winding 23a to 23d first to fourth excitation winding 30 detection coil 31 first winding 32th Two windings 33a to 33d First to fourth detection windings 50 Rotating shaft 80 Drill (cutting tool) 80b Shank 86 Comparator (determining means) 87 Control circuit (control signal generating means) 94 Cutting control device 94a PID controller ( Judgment means) 94b Feed speed calculation section (control signal generation means) 96 Spindle

Claims (9)

[Claims] 1. An exciting coil formed in a substantially eight shape by first and second windings wound in opposite directions, a detecting coil having substantially the same shape as the exciting coil, and both coils. A core having four pillar-shaped magnetic cores for mounting the coil, and the arrangement direction of the first and second windings forming the excitation coil, and the first and second windings of the detection coil. The windings of the coils are wound around the predetermined two adjacent magnetic cores, and the two adjacent magnetic cores are arranged while being overlapped with each other in a direction orthogonal to the arrangement direction. A magnetostrictive torque sensor characterized in that the direction is parallel or orthogonal to the axial direction of the rotating body to be measured. 2. The magnetostrictive torque sensor according to claim 1, wherein when the both coils are attached to the magnetic core, the exciting coil is arranged on the open side of the magnetic core. 3. The excitation coil and the detection coil,
3. The magnetostrictive torque sensor according to claim 2, wherein the magnetostrictive torque sensors are arranged apart from each other by a predetermined distance in the axial direction of the magnetic core. 4. The magnetostriction according to claim 1, wherein the core is integrally formed by forming a cross-shaped groove on one surface of a block body having a predetermined shape. Torque sensor. 5. The first to fourth exciting windings forming an exciting coil are arranged at each apex of a virtual quadrangle, and a current flows in the same direction in two adjacent exciting windings, and the remaining two windings are provided.
Arranging first to fourth detection windings, which are connected to the excitation winding of the book so that a current flows in the opposite direction, and which constitute a detection coil so as to overlap with the first to fourth excitation windings. The magnetostrictive torque sensor is characterized in that the direction of arrangement of the pair of excitation windings in which current flows in the same direction is parallel or orthogonal to the axial direction of the rotating body to be measured. 6. The magnetostrictive torque sensor according to claim 5, further comprising a core having four columnar magnetic cores, wherein each of the excitation windings and the detection windings is mounted on each of the magnetic cores. 7. The detection coil is further provided so as to measure the total amount of magnetic flux generated by the exciting coil, and the output of the detection coil is used to correct the output of the detection coil. The magnetostrictive torque sensor according to any one of 1 to 6. 8. The magnetostrictive torque sensor according to claim 7, and the magnetostrictive torque sensor, which is generated based on the outputs of the search coil and the detection coil obtained when rotating the torque detection target rotating body without applying torque. Storage means for storing the zero-point correction value data, and the zero-point correction value stored in the storage means is read from the output of the search coil when torque is applied to the rotating body, and the read zero-point correction value is read. A magnetostrictive torque measuring device further comprising a correction means for correcting the output of the detection coil based on the value. 9. The method according to claim 1, which is arranged outside the shank portion of the cutting tool that is attached to and detached from the machine tool main body or the spindle that rotates together with the cutting tool in a predetermined relative positional relationship with the axial direction. A magnetostrictive torque sensor according to claim 1 or a magnetostrictive torque measuring device according to claim 8, and an output of the magnetostrictive torque sensor or measuring device,
Judgment means for judging the presence or absence of breakage of the cutting tool attached to and detached from the machine tool main body, prediction of breakage, or desired state of the cutting tool such as wear, and the cutting tool based on the judgment result of the judgment means. A state detecting device for a cutting tool, comprising: a control signal generating means for outputting a predetermined control signal such as a deceleration command to a mounted drive device.