JPH10185709A - Detecting method for change state of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a detecting method for the change, the stress, the strain, the fatigue or the like of a substrate by a method wherein a fatigue degree based on an instantaneous stress value and a long-term stress value which are detected by a change in the electric resistance value of a magnetic-substance detecting piece is detected on the basis of a change in a magnetic characteristic. SOLUTION: A magnetic substance has a property that it is highly hard, that it is fragile, that it is highly corrosive and that it is broken down easily by a repetitive stress. A detecting piece detects the pressurization force, the fatigue or the like of a substrate on the basis of the coercive force, the magnetic flux density, the magnetoresistance or the like of a magnetic-characteristic detection value. The detecting piece is arranged directly with reference to a stress generating body, a position which generates the fatigue is grasped, or a change in a magnetization interval is measured, and the generation of the fatigue is estimated. For example, in a magnetism detecting structure by a detecting piece, a magnetic-flux detecting element 3 is bonded and fixed to an element-material central high-strain receiving part 2 which detects fatigue magnetically, and strain application grip parts 5, 6 are formed of a corrosion-resistant material. Members which receive a strain are coupled to external bonded parts 9, 9', and a connection part 8 is screwed and then brazed. Thereby, the fatigue can be estimated in a wide range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for detecting stress, strain, fatigue and the like of various members.

[0002]

2. Description of the Related Art Conventionally, as a strain gauge, there is a strain measurement method and the like for measuring the stress based on a resistance change due to expansion and contraction of a sensing piece due to a stress, and there is no method for measuring fatigue. Recently, a method of determining a change in magnetic properties of a structural member by a detector has been proposed. This results in a large-scale measuring device, which is difficult to use directly on site. For example,
1988, J. Appl. Phys 63 (8) 15 April DCJiles Iowa Stat
e Univ. and J.Appl.Phys75 (10) 15 May 1994
Estimation o by ZJ Chen, DC Jiles &, J. Kameda, etc.
f fatigue exposure from magnetic coercivity etc.

[0003]

The above-mentioned known paper J. Ap
As a gist of pl.Phys75 (10) 15 May 1994, regarding the structural material of the magnetic material, the relation H∽ln (N) in relation between the number N of stress repetitions and the coercive force H was announced. That is, the number of stress repetitions and the coercive force have a certain linearity. However, this is for structural steel materials, and magnetic materials as steel materials have extremely low corrosion resistance, and are also measured by attaching a magnetometer to the structural material itself. It is a similar method.

Generally speaking, a magnetic material is a material having high hardness, being brittle and difficult to be formed, and is also extremely corrosive and unstable. Since it is brittle and easily breaks due to repeated stress, it requires corrosion resistance and a stabilizer. In addition, since the device is small and easily detachable, or the destruction phenomenon due to fatigue requires a long time,
It is necessary to have a structure that can maintain various characteristics stably over a period of more than one year.

[0005] Therefore, the characteristic required as an element as a detecting piece is the development of a corrosion-resistant and highly stable magnetic material (more than 10 years). Development of a compact, vibration-resistant, inexpensive, and low power consumption system that allows easy attachment and detachment of the sensing magnetic material to and from the fatigue measurement object. Development of magnetic material with high fatigue resistance (10 ⁸ or more). Development of easy detection method with high S / N ratio for magnetic detection. The challenge is to simultaneously satisfy the above items.

The present invention does not detect changes directly,
Its magnetic characteristic detection values (coercive force, magnetic flux density, susceptibility,
(Magnetic resistance, magnetic permeability, impedance, etc.) to test for creep, pressure, fatigue, etc. of the material of the base material. , So as to be stable against vibration. The detection piece is an extremely small-sized device that can be easily attached directly to the actual product on site, and can easily determine the overall state. Further, the sensing piece can be made of a sufficiently stable crystalline or amorphous material.

[0007]

SUMMARY OF THE INVENTION The present invention can be set directly on the site where stress is generated, and can be detached as necessary.
Alternatively, by continuously arranging the sensing piece directly on the stress-generating body, the sensing piece is moved at the time of measurement so that the position where the magnetic change is caused by the encoder or the like can be accurately grasped. In order to detect the position of the change, the magnetism is arranged so that it can be detected. The value can be detected, and the change in the magnetization interval can be measured to predict the occurrence of fatigue.

A concentrated stress portion is formed into a shape using a magnetic material of an easily workable material, and a magnetoresistive element, a Hall element, and impedance measurement can be performed on the concentrated stress portion. Further, the change in the resistance value of the magnetic material can be directly detected as strain (number of times) based on the strain tension, and the number of times can be stored in the storage element to be used for fatigue prediction. The whole is shielded, and the number of strains is directly obtained from the change in the magnetic properties based on the dislocation in the magnetic body, so that a high SN ratio measurement that is stable against fatigue becomes possible.

Depending on the application, the SN can be improved by the notch method or the torsion method based on the stress concentration coefficient K = δm / δn. Further, a concentrated stress portion is formed by the pressurized deformation dent, and a magnetic detector can be attached to this portion to improve SN. It can be used in such a manner that the tension is controlled by the angle so that the object to be measured is tension-joined.

[0010]

According to another aspect of the present invention, when the workpiece is a non-magnetic material, it can be determined based on the rate of change in magnetic characteristics due to the tool itself. The tool itself at the time of cutting can be used as a detector. When the workpiece itself is a magnetic material, it can be used as a strain detector. Depending on whether the tool is used as a sensing piece, notch processing is used to detect that part, or measurement is performed before use, and measurement is determined according to the number of cuts, so that the tool, workpiece The fatigue resistance of each body is determined to predict the fatigue resistance after use.

In some cases, the processing accuracy can be determined. In this case, it can be predicted via magnetic measurement of the tool. In the case of measurement using a tool, since the torque (stress and strain) changes every moment during cutting, particularly the cutting edge receives high fatigue, so that the fatigue of the cutting edge can be predicted. Similarly, high stress is applied to the bearing portion, and strain is applied in tension and compression, so that the bearing naturally causes fatigue, and this can also be determined and predicted. Fatigue can be similarly predicted for those that generate fatigue due to thermal stress, such as boilers and turbine blades. In this case, it can be obtained by a change in magnetic characteristics due to itself.

When a sensing piece is used, in order to keep the properties of the sensing piece stable for a long period of time, a method utilizing spinodal transformation is used to keep the reaction at a stable point by a sufficient heat treatment. It is used as a line-shaped or band-shaped form subjected to amorphization. In the case of amorphous,
The characteristic can be detected very easily by crystallization due to stress strain. The support of the sensing piece is selected to have a sufficiently strong dimension for fatigue resistance, and may be subjected to a brazing treatment of a highly corrosion-resistant noble metal or the like.

[0013] In the case of using a short sensing piece, the stabilizing sensing piece for attaching the sensing piece to an object to be measured is
By forming such that a notch or a tensile torsional stress is applied and attaching a magnetic detector at that point, the entire stress can be concentrated, so that detection can be performed with high sensitivity. In the case of a short piece, the stress is applied directly to the detection piece, then cut off from the outside air with bellows or the like, and inserted into an inert gas Ar, He, etc.
To be able to maintain its basic characteristics stably for a long period of 0 years or 20 years. Further, the entire body may be wrapped with a synthetic resin-based elastic body having high corrosion resistance and high resistance to the elastic body.

As a practical detection piece, a hard magnetic material is mainly used, and a quenched martensitic alloy, a dispersion hardened alloy, a rolled magnet, a sintered magnet, and the like can be arbitrarily used. In particular, considering corrosion resistance, Pt-Fe-based, P
A t-Co type or the like is also advantageous. Further, amorphous ferromagnetic materials, Co-V-Cr-Fe-based materials, Fe-Cr-Co-based materials,
Cu-Ni-Fe material, Fe-Co-Mo material, 13C
Ferromagnetic materials such as r-based materials, piano wire materials, ferrite materials and the like can be almost used. That is, a paramagnetic hard or semi-hard material can also be used.

However, in general, when the material is left naturally,
A material with little metallographic or chemical change, and can be sufficiently applied to the present invention particularly for heat treatment such as molding and refining. This heat treatment includes a magnetic field heating / cooling heat treatment. In order to improve the corrosion resistance, the corrosion resistance is improved by a PVC or PVD treatment, and in some cases, a plating layer to improve the corrosion resistance, or a treatment such as encapsulation in a corrosion-resistant body is performed for stabilization. The shape is summarized as a structure that is small in size and allows the measuring instrument to be mechanically attached to the strained part with screws, bands, brazing, welding, etc.

[0016]

[Action] Considering the action of a magnetic material that can be used as a detecting piece, a ferromagnetic substance has a spontaneous magnetization inside, and the direction of the spontaneous magnet varies depending on the location. As a result, there is no magnetization as a whole. The crystal of the actual general material is an atomic vacancy (V
acancy) and defects such as interstitial atoms.

When the crystal is in thermodynamic equilibrium, FIG.
The number N of vacancies and interstitial atoms as described above is represented by the following equation.

(Equation 1) N ₀ : Vacancy or the number of places that can enter between lattices ε: Energy for forming a defect T: ΔK The crystal is deformed when a force higher than the energy (stress) for forming a certain defect is applied.

Dislocation is a lattice defect, which is a displacement of an atom generated in a crystal when deformed under stress. Furthermore, when annealing for a long time, dislocations tend to disappear. A dislocation is a dislocation in the arrangement of atoms at the center, and the dislocation energy is the sum of the dislocation energy and the stress-strain energy in the crystal of the atoms shown in FIG. 1, and the material breaks when the dislocation develops. Will be.

The magnetic internal structure of a ferromagnetic material has a very structure-sensitive property. Even if the repetitive stress is, for example, a stress within the elastic limit of the material, the repetition of the crystal causes Receives energy corresponding to the formula (1), and due to many repetitive stresses, the energy is accumulated and leads to destruction. Such a fracture is a fatigue fracture. Fatigue failure is said to be due to the aggregation and diffusion of vacancies or the accumulation of dislocations, but dislocations are always created by repeated stress.

Now, the amount of stress shear strain is represented as follows.

(Equation 2) d: average slip interval due to stress b: magnitude of Burgers-vector dislocation n: average number of dislocations The jog interval that generates vacancies is set to 1, the number of fatigue cycles is set to νHz, and vacancies generated per area of dislocation zone Given the number of

(Equation 3)r: Distortion amplitude b: Burgers vector (3 × 10^-8cm) 1 / K: helix dislocation rate during dislocation slip (0.1) For example, n = 7 × 10¹⁴/cm^TwoAnd per unit area
The number of atoms is 10¹⁷/cm ^TwoSo it's about 1%
And cause fatigue fracture.

Normally, when a magnetic material, especially a ferromagnetic material, is applied with a magnetic field, each magnetic domain changes its direction in the direction of the magnetic field.
Orientation in one direction increases magnetization as a whole. For example, in the case of iron, magnetic domains are generated in the crystal in six directions of the <100> plane of the easy magnetization direction of Fe in the crystal. In the magnetic domain, not only some electrons of the atoms of the ferromagnetic material have a certain value of mass m and a negative value of (-), but also the inherent dynamic efficiency (Spi).
n) is a mechanical atomic field that can only change two antiparallel directions with respect to an external magnetic field.

There is a domain wall between one magnetic domain and an adjacent magnetic domain, and the domain wall moves and is magnetized. Now, assuming that the length of the magnetic domain is l, the volume of the magnetic domain is proportional to l ³ , and the magnetic domain of the magnetic material always tries to minimize its energy, and the object is stabilized as a balance including the magnetic domain. .

[0023]

(Equation 4) I: Magnetization strength S: Surface area of magnetic domain (l ² ) V: Volume of magnetic domain (l ³ ) σ: Surface tension (KI ² l calculated from Curie point: K ≒)
10 ⁴ ) The length l of the magnetic domain is as follows.

(Equation 5) L: ≒ l ²

The magnetic domain ultimately governs the magnetic properties of the magnetic material. In order to cross the domain wall at the boundary between the two magnetic sections, the energy required by the equations (2) and (3) is required. Become. If dislocation occurs in the material and the domain wall is distorted, it receives mechanical energy and the magnetic properties of the sensing piece change. This change is detected by a magnetic element.

When detecting magnetism, there are a method of detecting with a magnetoresistive element and a Hall element, and a method of directly detecting as impedance. Now, in the impedance detection, I _HF (high frequency current) is applied to the magnetic wire (radius a length l).
, The magnetic flux φ changes due to the magnetic change due to the stress during the magnetic detection. In the case of a high frequency, the change is particularly large in the surface layer.

If the induced voltage at both ends of the sensing piece is e _L ,

(Equation 6) Becomes Therefore, assuming that the voltage across the sensing piece is E,

(Equation 7) When the voltage E is directly measured, it indicates a magnetic change of the sensing piece, and the distortion can be determined.

The motion of the magnetic domain caused by the magnetic field is greatly changed by the above-mentioned defect of the crystal structure. The factors of the physical quantity of the change depend on the crystal structure, impurities, and strain (stress) based on the chemical composition of the magnetic material. The same structural sensitivity is obtained in both hard magnetic materials and soft magnetic materials. Now consider a disk-shaped single magnetic domain, and when it is magnetized, the magnetic domain rotates in the direction of magnetization and expands or contracts. The shape at this time is
If the volumes are equal, it will be a distorted ellipse.

In FIG. 2, a is a spontaneous magnetism state immediately after the heat treatment, and b is a state where spontaneous magnetism is generated after aging treatment. Also, if c shrinks when an external magnetic field is applied,
In the case of extension, the opposite state is shown. Of course, the detection piece of the used fatigue meter can be arbitrarily manufactured depending on the degree of molding.

Conversely, when a magnetic change is applied to a stress, the magnetic permeability changes very sensitively when a stress is applied. This is because magnetic domains are easily rearranged and configured by magnetization. The stress strain is as follows. ε _T = ε _M + ε _C ε _T : Total strain ε _M : Strain due to magnetic domain ε _C : Elastic strain Further, the rearrangement of magnetic domains is irreversible, and the strain can be stored sufficiently stably.

When a tensile stress is applied to a material having a positive magnetostriction and the material is further magnetized, much magnetostriction does not occur. The opposite is true for compressive stress. If the magnetostriction is negative, the opposite is true.
If the magnetostriction λ is positive, the magnetostriction is reduced by tensile stress, and if λ is negative, the tensile stress increases λ.

FIG. 3 shows these relationships. There is a domain wall between each of the magnetic domains, and the magnetic domains move around this. According to FIG. 2, zero magnetostriction means that the state shown in FIG. 4 is obtained while having spontaneous magnetic domains. There is a difference in the direction of the magnetic domain depending on the presence or absence of magnetostriction, and it is divided by the difference between the spontaneous magnetism in the circumferential direction and the spontaneous magnetism in the line length direction. Therefore, it should be noted that the value of the expression (6) of the e _L value changes when the magnetic field changes.

After all, the effect that the magnetic characteristics change due to the external pressure differs depending on the properties of the magnetic strain sensing piece.
In any case, the stress → strain → magnetic change always occurs. First, when the sensing piece is magnetized, when the magnet (domain wall) is energized to move the magnetic domains and the walls of the magnetic domains together with the non-magnetized case, the magnetism decreases when magnetized,
It changes proportionally with stress. Similarly, in the case of non-magnetization, if the energy for moving the domain wall is applied from the stress,
The magnetic power changes accordingly.

In a metal body, the crystal form belongs to any of body-centered cubic, face-centered cubic, and dense cubic, and the magnetic body is mainly a transition metal-based cubic. In order to maintain sufficient stability, in general, a supersaturated solid solution is produced by heat treatment solution treatment, a uniform distribution of solute atoms is secured, and then quenching is performed to rapidly maintain a supersaturated state, and optionally Dispersion processing or the like due to the desired crystal strain or fine precipitation may be caused, and aging treatment may be performed in a magnetic field. Further, in some cases, mechanical strong processing is performed to give directionality while refining the crystal so as to obtain desired mechanical properties and magnetic properties at the same time.

In order to partially apply the concentrated cumulative stress to the sensing piece, a shape such that a torsional bending stress is applied as shown in FIG. 5 is tried. When a pull force is applied, it becomes as follows. Here, P is a tensile force and W is a tensile stress. W = P sin α If the shear force is F, then F = P cos α, and if the torsional moment is T, then T = PR cos α. When the bending moment is M, the torsional moment receives M = PR sin α. If the torsional shear force is the average shear force,

(Equation 8) And the maximum shear stress is as follows.

(Equation 9) Furthermore, the torsional stress is

(Equation 10) And it becomes easy to detect fatigue from this portion (see FIG. 5). As shown in FIG. 6, it is shown that torsion effectively causes fatigue with the lowest applied stress. Therefore, equation (9) can be used.

When stress is applied to the crystalline or amorphous body, the stress concentrates on the portion around the dislocation, and the parallelism of the spin around the dislocation is disturbed. Looking at the case of Fe,
The energy of the domain wall is generally about 10 ⁻³ J / m ² , and the propagation energy of the crack is about 1 J / m ² . The magnetic properties change with a small amount of energy due to the domain wall exchange effect due to the strain force.

The phenomenon of phase separation is that when a high-concentration alloy is decomposed, the free energy increases due to the concentration fluctuation in the downward convex curve with respect to the composition, so that the concentration fluctuation cannot be developed. Therefore it disappears. Further, in the upward convex curve, the free energy decreases due to the fluctuation of the density, so that it becomes stable with time, and the convex point becomes a constant density. This spinodal decomposition is caused and progresses as a cooperative phenomenon as well as regularization, and can be stabilized.
Therefore, the solid solution initially grows as a short-wavelength fluctuation wave, and becomes a long-wavelength wave with time, and it can be said that the solid solution has a metastable composition region. After all, it can be determined by the curvature of the curve between the free energy and the composition concentration.

Fatigue has almost nothing to do with stress. When fatigue occurs, it is necessary to consider that there is almost no residual stress. FIG. 8 shows this relationship for carbon steel. In other words, it indicates that even if the residual stress is measured, fatigue cannot be predicted at that time.

According to the cutting action, generally, in the case of iron, at least about 10 cal / mm ³ (up to 10,000 cal / mm ³ )
Since it is applied to the cutting edge portion or the processing portion, the cutting edge or the portion supporting the cutting edge during cutting is in a state of receiving high temperature and high stress. When a magnetic material is interposed, a magnetic change occurs, so that the life of the cutting edge can be predicted. The cutting angle, tip radius, and the like of the cutting edge can be magnetically detected to predict the life of the tool in advance or during cutting. Therefore, it is possible to demagnetize at the beginning of processing or to start processing after magnetization. Cutting tool tip is 50
It will be subjected to strain stress at a high temperature of 0 ° C. or higher and a high pressure of 50 to 100 kgf / mm ² .

FIG. 7 shows an example having a notch. In the case of a smooth material due to the fracture stress of the material, a parabolic stress is generated as δ. Therefore, it can be considered that concentrated stress is generated at the bottom of the notch due to the notch, a slip band is generated, and the concentrated force is superimposed, thereby causing fatigue cracks. The relationship between the output voltage V _H of the magnetic detector and the number of strain repetitions can be expressed as V _H = Kln (N). At this time, the constant K corresponds to the notch, and the K value decreases due to the notch.

As an amorphous magnetic alloy, an iron alloy is used.
For example _{Fe 80 P 20, Fe 80 B} 20, Fe 78 B 10 Si 12, F
e ₆₂ Cr ₁₂ Mo ₈ C _18, etc., in the cobalt Co ₈₀ Zr
₂₀ , Co ₇₈ Si ₁₅ B ₁₂ , Co ₄₄ Mo ₃₆ C ₂₀ , Co ₃₄ Cr
₂₈ Mo ₂₀ C ₁₈ etc., Ni alloy type, Ni ₉₀ Zr ₁₀ , Ni ₃₄
Cr ₂₄ Mo ₂₄ C ₁₈ , other alloys Pd ₈₀ Si ₂₀ , Ti
₅₀ Cu _{50 and} so on. The tensile strength is 400kgf / mm
^The fatigue life is about ^{2 to} 140 kgf / mm ² , for example, Pd ₈₀ Si ₂₀ and 32 kgf / mm ² , and the fatigue life is 10 ⁸ times. The relationship between the size P of the plastic zone at the tip of the fatigue and the stress intensity factor K is as follows.

P∽K ⁿ Here, n ≒ 2, which indicates that the amorphous material is extremely stable, structurally homogeneous, and an excellent plastic body. Fatigue limit ratio (fatigue strength / yield strength) is 0.2
~ 0.3, equal to general high-strength materials. Therefore, it is one effective material utilizing the corrosion resistance of the amorphous magnetic material. Conventionally, generally, there is little relation between fatigue and residual stress. This is as shown in FIG.

[0042]

Example 1 As an example, a PtCo magnet having at% 50 and at50 was subjected to a five-stage heating wire drawing process, and a reduction ratio of 50% or less was obtained.
After drawing by 22%, a 0.45 mmφ material was straightened, and a fatigue test was carried out using a cantilever at 1500 times / minute.
The test was performed by fixing a Hall element to a fixed portion with a projection length of 22 mm, a tip amplitude of 1 mm, and a fixed portion. At this time, the maximum bending stress is 30.4
the kg / mm ^2. The substrate is 139 kg / mm ² , which is considered to be 0.2 kg proof stress at 142 kg / mm ² . Therefore, the test was performed at a 22% load (see FIGS. 9A and 9B). That is 6.2 Oe coercive force to start with 10 ⁷ times becomes 0.5 Oe. 10% coercive force
The following shows that the material is undergoing fatigue.
FIG. 9B uses the method of FIG. The 13Cr material is shown in FIG.

[0043]

In Example 2 the same conditions, at 10 ^seven pressurized strain cycle coercivity material 0.06Oe the beginning, was about 8 times the 0.5 Oe. This is shown in FIG.

[0044]

Embodiment 3 In the same PtCo material, one kink-like point is formed to be 1R. The α angle in FIG. 5 is 45 ° and R = 12.5
mm and d = 0.45 mm. The test was performed with a magnetostrictive material of 300 Hz at a tension P = 40 g. This means that a torsional stress of 12.2 kg / mm ² was applied. This is about 1/10 of the load, but it is detected very effectively compared to the overall strain characteristics. That is,
Displaying a degree of fatigue to be a 10Oe at the beginning to 10 ⁷ times of the pressure distortion at 8 Oe.

[0045]

Example 4 After the quenching treatment of Cr13% Mn1% Fe, a tempering heat treatment was performed to make the hardness Hv500, but a 0.45 mmφ one was used. Kaibitsu conditions 1500 times / min conditions, the mechanical strength of the material is 98kgf / mm ^2, to 96kgf / mm ² as a 0.2% yield strength was carried out at a load of 9.5kgf / mm ² (10%) . This is shown in FIG.

[0046]

Example 5 In FeCr28% Co15% Mo3% material, after drawing, 0.96mmφ was decreased from 610 ° C to 500 ° C at 4 ° C / h, 200mm length and 250 Oe at open terminal.
After 10 ⁸ repetitions, it became 15 Oe. In this case 9.6kgf
The test was performed under a stress of / mm ² . This was used as a full spinodal transformation.

[0047]

Embodiment 6 WC + TiCTia 14% + Co10% sintered material
By, 65kgf / mm of stainless steel ^TwoTo the material
The angle of rake is 12 °, the rake angle on the land is 0, and the front clearance angle is sideways.
Cutting at a cutting angle of 110 m / min with a 10 ° angle
Liquid mineral oil was used at 10 l / min. The case is shown in FIG.
You. The result of the dry cutting is shown in FIG. That is, the blade
High strain is applied to the previous part, mainly for Co
The demagnetization state was measured. When magnetized, the cutting tip
It was difficult to measure, but a tendency was observed.
Was. Therefore, if you measure online,
As a result, stable accuracy can be guaranteed.

[0048]

[Example 7] Concentration 100, natural diamond 80
0 #, a core material was magnetized using an electrodeposited IO cutter using a 13Cr material, and a core material was measured using a non-magnetized material. An Al ₂ O ₃ SiN ₂ ceramic material was machined as a material to be cut. At the time of cutting, A is magnetized with the parallelism accuracy of the cut material,
A 'is in a non-magnetized state. FIG. 12 shows a working example thereof.
The cutting speed was 55 m / s in all cases, and was carried out using kerosene cutting oil. As a result, the cutting life could be predicted.

[0049]

[Embodiment 8] In a 1.3 mm φ bone cutting reamer, 4 to
The bone caries was cut with 5RPM. The bending base material used 13Cr stainless steel hardness Hv500. When cutting with 45R,
In the case of non-magnetism, the intensity of the magnetic field Oe was about three times that at the start immediately before the reamer break. Other medical tools can predict fracture very stably. It turned out that it can be used for injection needles, grinding tools (diamonds), saw blades, chisels, cutters, etc.

[0050]

Embodiment 9 Wt% (Cr29% Co15% Mo3% Fe)
After forging and forging HF in Ar,
After heat treatment at 8 ° C / H to 0 ° C, 10cm from the end face with 20cm length
2mm thick NdBFe magnet (48MGO) at cm (center)
FIG. 13 shows voltage waveforms when the magnetized NS is brought closer to the position of 5 mm, and when an attenuation wave of 2.5 MHz is applied when not magnetized. As can be seen from this figure, it can be detected as impedance by magnetization. Also,
In this state, when the magnetic sensing material receives a strong Psin α, the resistance value is detected by the ratio of the wire length of the magnetic material to the elongation Δl / l, and both the fatigue measurement and the strain are simultaneously measured. Can be. In this case, it is necessary to insulate the connection between the magnetic material and the force terminal. The ceramics are mechanically joined by surface pressure.

[0051]

[Embodiment 10] An embodiment as a structure will be described. As an embedding type airtight device, an inert gas can be sealed in the inside or embedding with a stable resin or the like can be used. In any case, the detector is used after being bonded or tied to the magnetic detection material or wound and fixed. Further, the resin case and the filler can be used together without the metal case. Furthermore, the resin case may be filled with resin. This embodiment is shown in FIG.

Here, (1) is a base magnetic material, a high strain-receiving portion (torsion) at the center of the element material for detecting fatigue magnetically.
A magnetic flux detecting element Hall element (3) is adhered to (2), and an upper part thereof is fixed with an elastic synthetic resin rubber (4). Strained pattern parts (5) and (6) are made of corrosion-resistant stainless steel or precious metal,
It can be used as Ti-based. External joint (9)
(9 ') It couple | bonds with the member which receives a distortion. The connection part (8) is brazed after screwing. A signal is taken out to the outside through the airtight terminal (7) or the induction coil in a non-contact manner, or a start / stop signal is supplied from outside.

The apparatus of the embodiment shown in FIG. 14 will be described.
(A) uses a long-life power source battery such as a Li battery, and receives and receives signals via a control device (B). The elastic rubber plugs (10), (11), (12), and (13) are support portions of the main body, and the main body (16) and the movable bellows (14, 15) are all formed of a corrosion-resistant material. Further, an inert gas is injected from the sealing port of (17). And (18) (19) (2
Each of 0, 21, 22, 23, 24, and 25 is hermetically welded with a platinum alloy solder and a gold solder.

It is also possible to mechanically join via partial ends (9) and (9 ') which are directly subjected to strain, and then embed in cement or place in air or liquid. It has a structure that does not cause corrosion. The entire power supply is turned on by a signal from the outside by the circuit (B) including the computer, and the result is supplied to the outside as a signal from the magnetometer. It is also easy to output it as a signal as a repetitive strain number to the outside. Of course, stable output can be achieved while preventing temperature and other drifts. In each case, it is naturally necessary to maintain a life of 10 years or more.

[0055]

Embodiment 11 FIG. 16 shows an embodiment in which a wire (band) material magnetic material is used for structures, buildings, large materials, and the like. Members (1) and (2) for the strain-receiving material joint (A)
(B) (C) The rivet member (3) is pressed by the capstan (7) and the presser (8) with a magnetic wire and moves (3) the magnetic material at the time of measurement to contact the measurement discrimination head (9). Detect the magnetic field. Of course, in the case of such a large size, the amount of distortion is also detected. Magnetization is performed at regular intervals to determine the pitch, and a part that receives particularly strong stress is detected. The stators (4), (5) and (6) can be discriminated by always fixing them with the support portion ceramic resin and loosening and moving them during measurement. It is also possible to perform measurement by connecting the unit units (FIG. 15) in series.

[0056]

Embodiment 12 Amorphous magnetic material Pd80Si20 material 20 μm thick 15 mm width 20 cm length One end of permanent magnet 0.3 mm φ 2 mm length PrCo3, 9 kg 8 KOc material bonded to one end with epoxy resin, 800% tensile stress is applied When tension
As a result of repeatedly applying stress at 45 kgf / mm ² , the life was 8 × 10 ⁶ cycles.

[0057]

Embodiment 13 When this detector is set, a stator is set for an object to be measured and discriminated, and the joining tension between the detector and the structure is adjusted with screws and set.
14 and 15, the measurement setting bar of the stress determination bar (26) is inserted into the detector of another case (27), and both ends are fixed with screws, and then the setting bar is removed. The setting bar has a size in which the strength of the stress can be changed, and is practical. When the measured object is the iron material X, it is fixed with screws. At this time, the stress of the object to be measured is applied only to the detector together with X so that the detector is not affected even if the detector is directly embedded in the concrete with an elastic cover such as an elastic synthetic resin (28) (see FIG. 15).

[0058]

[Embodiment 14] FIG. 16 shows a system using a long detecting piece (1) used for a vehicle different from FIG. The long detection piece magnetic material is always fixed. Stator (31) (32) (33)
··························································································································· while moving the stator by the capstan with encoder (29) and the holder (30). , The degree of fatigue is detected by a magnetic detector (3). Therefore, in the case of a long length, the stator is a chuck type, and the magnetic material is fixed by always sandwiching the chuck, and then the chuck stator is opened so as to be movable during measurement.

[0059]

The present invention makes it possible to predict fatigue, which cannot be measured conventionally, in a very wide range, and is industrially extremely practical.

[Brief description of the drawings]

FIG. 1 shows vacancies and interstitial atoms.

FIG. 2 is a schematic diagram of magnetostriction, in which a is a spontaneous magnetism state immediately after heat treatment, b is a case where spontaneous magnetism is generated by aging treatment, and c is a case where the magnet is contracted when an external magnetic field is applied.

FIG. 3 is a diagram showing a relationship between a magnetic domain, stress, and a magnetic field.

FIG. 4 is a diagram showing magnetic domains of a positive and negative magnetostrictive material and a zero magnetostrictive material.

FIG. 5 is a diagram showing a relationship between torsional, bending stress and tensile force.

FIG. 6 is a diagram showing the relationship between the tensile strength of steel and the fatigue limit.

FIG. 7 is a diagram of a sensing piece having a notch.

FIG. 8 is a diagram showing the relationship between the residual stress of various materials and the number of repetitions.

FIG. 9 is a diagram showing the relationship between the number of repetitions and the coercive force depending on the material and shape.

FIG. 10 is a diagram illustrating a relationship between the number of repetitions of a spinodal transformation material and a coercive force.

FIG. 11 is a diagram relating to crater wear and coercive force.

FIG. 12 is a diagram illustrating a relationship between a bending amount by a cutting cutter and a coercive force.

FIG. 13 is a diagram illustrating a state of change in impedance due to magnetization of a sensing piece.

FIG. 14 is a side sectional view of the embedded airtight detector.

FIG. 15 is a diagram of a unit of a system wrapped with another elastic resin.

FIG. 16 is a diagram of a fatigue detection device having a different structure from that of FIG.

[Description of sign]

1 ····· Magnetostrictive characteristic material 2 ····· Magnetic characteristic detector (magnetic resistance element) Hall element 7 ··· ···················································································, Elastic airtight stopper 12 ··· Corrosion-proof airtight case 14, 15 ····· Bellows 17 ··· Inert gas supply sealing port 18 … 25: airtight and corrosion-resistant soldered part A: control cct (including batteries)

Claims (9)

[Claims] 1. A magnetic material, which is magnetized or non-magnetized, is attached to a member which receives stress strain so as to be able to receive stress strain, and a magnetic characteristic changed due to stress distortion of a magnetic characteristic of the magnetic material. A method for detecting a change state of a base material, which detects a degree of fatigue of a stress-strained material by measuring. 2. A method for detecting a change state of a base material, wherein an instantaneous stress value detected by a change in an electric resistance value of a magnetic substance detecting piece and a degree of fatigue based on a long-term stress are detected from a change in magnetic properties. 3. The method according to claim 1, further comprising a step of providing an end face of the detecting piece or a part which is particularly strong and easily causes a magnetic change, and attaching a magnetic change measuring device. 4. A change state detecting device for a base material in which a lead portion made of a high magnetic permeability material is provided as an arbitrary measuring terminal on a detecting piece, or a magnetic change is inductively extracted to the outside. 5. A base material in which a long detection piece is formed into a tape or a wire and fixed to a measurement base material at all times, and a tape or a wire is moved at the time of determination to measure and determine magnetic properties. Change state detection method. 6. A magnetic field detecting tape or a wire-shaped detecting piece is stretched around a mountain, a wall, a cliff, a bank, a building, a support, a pile, or the like, and a magnetic field detecting tape or a wire-shaped detecting piece is provided on a road. 2. The method according to claim 1, wherein the magnetic property of the state at a predetermined location is detected by embedding the information. 7. When processing a magnetic material, a magnetic detector is scanned according to its shape after processing, and a magnetic change is detected to evaluate the state of processing or to determine the life of the workpiece. Method. 8. Detecting cutting characteristics of a tool by detecting a change in magnetic properties of the tool from the start of processing during or after processing of a cutting tool (cutting, cutting, polishing, etc.) and detecting a cutting state and life of the tool. apparatus. 9. The apparatus according to claim 1, wherein a change in magnetic property is detected as a change in impedance.