JP2012026737A - Eddy current flaw detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deepen flaw detection depth of a device which detects a flow of nonmagnetic metal, to make the device highly sensitive, and to make the device into product configuration with high reliability.SOLUTION: An exciter consists of an iron core in the portal cross-sectional shape and an exciting coil, the iron core in the portal cross-sectional shape consists of a first leg, a second leg, and a beam part for connecting both legs, the first leg is thinner than the second leg, the exciting coil is wound in the surroundings of the first leg, when a nonmetal test body is a non-magnetic stainless steel alloy material, a second current line of the exciting coil which passes through the outside of the thin first leg of the iron core is located at a position higher than a first current line which passes between the first and second legs of the iron core and so as not to exceed height of the iron core, a receiver in which a reception coil is wound around the tip side of a rod-like iron core is set to an angle so as not to interlink a magnetic flux of a primary magnetic field under a state where there is no nonmetal test body at a position where the receiver does not contact the outside of the thick second leg of the exciter.

Description

  The present invention relates to a technique for inducing an eddy current in a metal specimen by applying a primary magnetic field to the metal specimen and detecting a secondary magnetic field returned from the eddy current.

  When testing or inspecting a conductive metal specimen, an exciting coil and a receiving coil are arranged close to the surface of the metal specimen, an alternating current is passed through the exciting coil, and a primary magnetic field is generated in the exciting coil. Then, an eddy current is induced in the metal specimen. A secondary magnetic field is generated from the eddy current. In the receiving coil in both the primary magnetic field and the secondary magnetic field, the interlinkage magnetic flux of both magnetic fields induces a combined electromotive force. The presence or absence of a flaw is determined based on the combined electromotive force and detection signal of the receiving coil.

    In the flaw detection method in which the excitation coil and the reception coil are separated, there are a method in which the excitation coil surface is parallel to the flaw detection surface of the conductor and a method in which the excitation coil surface is orthogonal to the flaw detection surface of the conductor. Further, Patent Document 1 shows a method in which an excitation coil is wound around an iron core having a gate-shaped cross section, and a receiver in which a reception coil is wound around a rod-shaped iron core is inclined with respect to the detection surface. Yes.

JP 2008-241685 A

[Background issues]
The problems of Patent Document 1 are listed. First, a higher sensitivity is required. Secondly, since the optimal winding position of the exciting coil and the tilt angle of the receiver differ depending on the material of the subject metal, it is more sensitive to set the winding position of the exciting coil and the tilt angle of the receiver for each material. What you can get. Third, the detection surface needs to be durable against contact with the subject metal and friction. Fourth, the tilt angle of the receiver does not change with changes in ambient temperature or external stress. Fifth, it must be made accurately in a short time for mass production.

[Leg width of iron core with portal cross section]
As shown in FIGS. 1 and 2, the second leg 5 of the exciter 9 is thicker than the first leg 4. By thickening the second leg portion 5, the magnetic shielding effect is enhanced, the magnetic flux density of the primary magnetic field in the space area on the receiver side is lowered, and the linkage flux of the primary magnetic field applied to the receiver 15 is reduced. The thick second leg 5 makes the receiver more insensitive to the primary magnetic field. The receiver can be made more sensitive to secondary magnetic fields.

[Excitation coil winding position in non-magnetic stainless steel]
When the nonmagnetic stainless steel is a metal sample, the exciting coil 1 wound around the iron core 2 having the gate-shaped cross section of the exciter 9 shown in FIG. 1 has the first coil side 7 and the second leg 4 of the iron core 2 and the second. Between the leg parts 5 and located below the beam part 6, the second coil side 8 is outside the first leg part 4, is higher than the first coil side 7, and has a portal cross-sectional shape of the iron core 2. Located in a location not exceeding the height. By arranging the second coil side 8 at a position higher than the first coil side 7, the primary minimum RMS inclination angle 28 on which the receiver 15 is placed becomes closer to the vertical, the flaw detection depth is increased, and the flaw detection sensitivity of the receiver is increased. Will improve.

[Optimum receiver tilt angle with non-magnetic stainless steel]
The inclination angle 14 of the receiver when the nonmagnetic stainless steel is a metal sample is shown in FIG. 1, and the characteristics of the inclination angles 14 and 21 are shown in FIG. A thick solid line 24 in FIG. 3 represents the interlinkage magnetic flux component of the primary magnetic field generated by the exciting coil 1 when there is no secondary magnetic field, that is, when there is no metal specimen. Due to the difference in the direction penetrating the receiving coil 10, the flux linkage has a polarity and the phase is 180 degrees different. The inclination angle at which the interlinkage magnetic flux component 24 of the primary magnetic field becomes zero is defined as a primary minimum RMS inclination angle 28. The primary minimum RMS inclination angle 28 means that a coil having a finite thickness and the number of turns cannot obtain a complete linkage flux zero, and the RMS value of the reception voltage converted from the electromotive force of the reception coil is zero. Take the minimum value close to. The left side of the primary minimum RMS inclination angle 28 is the increase 22 of the inclination angle 14 of the receiver, and the right side is the decrease 23 of the inclination angle 14.

When a non-magnetic stainless metal specimen approaches the exciter 9 and the receiver 15, an eddy current is induced in the metal specimen, and a secondary magnetic field is returned from the eddy current. A thin solid line 25 represents the interlinkage magnetic flux component of the secondary magnetic field returned from the thick nonmagnetic stainless steel material. The thin broken line 27 represents the interlinkage magnetic flux component of the secondary magnetic field returned from the thin nonmagnetic stainless steel material. When the nonmagnetic stainless steel material is thick or thin, the primary magnetic field and the secondary magnetic field cancel each other on the right side of the primary minimum RMS inclination angle, that is, on the side where the inclination angle decreases, and the RMS value of the reception voltage becomes minimum. An angle is obtained. This is the secondary minimum RMS tilt angle 29. The secondary minimum RMS tilt angle 29 is not completely zero because the secondary and primary magnetic fields are not perfectly 180 degrees out of phase. When the non-magnetic stainless steel material is a metal sample, the inclination angle 14 of the receiver is set to the primary minimum RMS inclination angle 28. Non-magnetic stainless steel has a low electrical conductivity, and therefore a low eddy current density, resulting in a weak secondary magnetic field. By placing the receiver at an inclination angle that makes the primary magnetic field insensitive, it becomes more sensitive to the secondary magnetic field, deepens the flaw detection depth, and improves the sensitivity to scratches and defects.

[Winding position of exciting coil in aluminum material]
When aluminum is a metal specimen, the exciting coil 1 wound around the iron core 2 having the gate-shaped cross section of the exciter 9 in FIG. 2 has the first coil side 7 having the first leg 4 and the second leg of the iron core 2. 5, located below the beam portion 6, and the second coil side 8 is outside the first leg portion 4 and is located at the same height parallel to the first coil side 7. Since the second coil side 8 and the first coil side 7 are parallel and positioned at the same height, the secondary minimum RMS inclination angle 29 on which the receiver 15 is placed approaches more vertically, the depth of flaw detection increases, and reception Improves the flaw detection sensitivity

[Optimum receiver tilt angle with aluminum]
FIG. 2 shows the inclination angle 14 of the receiver when aluminum is a metal sample, and FIG. 4 shows the characteristics of the inclination angles 14 and 21. A thick solid line 24 in FIG. 4 represents the interlinkage magnetic flux component of the primary magnetic field generated by the exciting coil 1 when there is no secondary magnetic field, that is, when there is no metal specimen. Due to the difference in the direction penetrating the receiving coil 10, the flux linkage has a polarity and the phase is 180 degrees different. The inclination angle at which the interlinkage magnetic flux component 24 of the primary magnetic field becomes zero is defined as a primary minimum RMS inclination angle 28. The primary minimum RMS inclination angle 28 means that a coil having a finite thickness and the number of turns cannot obtain a complete linkage flux zero, and the RMS value of the reception voltage converted from the electromotive force of the reception coil is zero. Take the minimum value close to. The left side of the primary minimum RMS inclination angle 28 is the increase 22 of the inclination angle 14 of the receiver, and the right side is the decrease 23 of the inclination angle 14.

When an aluminum metal specimen approaches the exciter 9 and the receiver 15, an eddy current is induced in the metal specimen, and a secondary magnetic field is returned from the eddy current. A thin solid line 25 represents the interlinkage magnetic flux component of the secondary magnetic field returned from the thick aluminum material. The thin broken line 26 represents the interlinkage magnetic flux component of the secondary magnetic field returned from the intermediate thickness aluminum material. The thin alternate long and short dash line 27 represents the interlinkage magnetic flux component of the secondary magnetic field returned from the thin aluminum material. When the aluminum material is thick, medium, thin, and on the right side of the primary minimum RMS tilt angle, that is, on the side where the tilt angle decreases, the primary magnetic field and the secondary magnetic field cancel each other, and the RMS value of the received voltage is The smallest angle is obtained. This is the secondary minimum RMS tilt angle 29. The secondary minimum RMS tilt angle is not completely zero because the secondary and primary magnetic fields are not perfectly 180 degrees out of phase.

When the aluminum material is a metal specimen, the inclination angle 14 of the receiver is set to the secondary minimum RMS inclination angle 29 with the aluminum metal specimen having a thickness exceeding the flaw detection depth limit. Aluminum material has a high conductivity, and thus a high eddy current density, resulting in a strong secondary magnetic field. If the receiver 15 is set to the primary minimum RMS tilt angle 28, the reception intensity of the secondary magnetic field is too strong, and the dynamic range is exceeded with a small thickness, so that the amplification factor is not increased. However, the sensitivity to scratches cannot be obtained. The receiver 15 is set to the secondary minimum RMS inclination angle 29 in which the primary magnetic field and the secondary magnetic field cancel each other using an aluminum material having a thickness exceeding the flaw detection depth limit. After setting the receiver 15 at this inclination angle, the amplification factor or excitation current of the amplifier is increased to a level where the output voltage subjected to RMS-DC conversion does not exceed the dynamic range in the absence of an aluminum sample. As for the output voltage, the minimum voltage is obtained with the thickest material of aluminum, and the output voltage rises due to thinning or scratches, and the maximum voltage is obtained in the state where there is no subject. This output voltage characteristic is reversed with the output characteristic of the nonmagnetic stainless steel flaw detector. The setting of the receiver 15 to the secondary minimum RMS inclination angle 29 becomes more sensitive to the secondary magnetic field returned from the aluminum material, the depth of flaw detection becomes deeper, and the sensitivity to flaws and defects improves. The flaw detection depth limit is the maximum thickness that the aluminum flaw detection apparatus can respond to, and is roughly calculated from the skin effect calculation formula as the depth at which electromagnetic waves can penetrate.

[Receiver structure and cable connection]
As shown in FIG. 5, in the receiver, a receiving coil 30 is wound around a rod-shaped iron core 31 having a tip wedge portion 33 so as to be biased to a tip portion near the detection surface. For the iron core, a soft ferrite material having a high initial permeability and a high volume resistivity is used. The tip wedge portion 33 serves as a rotation center for tilting the receiver. A double-sided PCB substrate 32 is used for connection between the receiver and the cable. The front surface copper foil pattern 34 and the back surface copper foil pattern 35 of the double-sided PCB substrate 32 have the same shape and the same position so that no interlinkage magnetic flux is generated on the substrate. The ends of the coil windings are soldered to the coil wire soldering lands 36, respectively. The receiving cable is a shielded twisted pair wire, and the core wire of the twisted pair wire is soldered to the cable core wire soldering land 37. The rod-shaped iron core 31 around which the receiving coil 30 is wound is bonded onto the double-sided PCB substrate 32 at a portion where the receiving coil 30 is not wound.

[Exciter cable connection]
As shown in FIG. 6, in the exciter, an exciting coil 41 is wound around a leg on one side around an iron core 42 having a gate-shaped cross section. For the iron core, a soft ferrite material having a high initial permeability and a high volume resistivity is used. A single-sided PCB substrate 43 is used for connection between the exciter and the cable. Two surface copper foil patterns 44 are provided only on the substrate surface, and the distance between the two patterns is made as narrow as possible in order to suppress the generation of a magnetic field from the substrate. Each end of the coil winding is soldered to a coil wire soldering land 45. The exciting cable is a shielded twisted pair wire, and the core wire of the twisted pair wire is soldered to the cable core wire soldering land 46, respectively. The single-sided PCB substrate 43 is bonded onto the iron core 42 having a gate-shaped cross section.

[Detection face plate]
As shown in FIG. 7, the receiver 56 and the exciter 59 are installed on the upper surface of the detection face plate 51. The lower surface of the detection surface plate 51 is a detection surface 52 that contacts or rubs against the metal sample. On the upper surface of the detection face plate 51, a receiver inclined triangular groove 53 is cut. The front end wedge portion 55 of the receiver is fitted here. The opening angle of the receiver inclined triangular groove 53 is sufficiently wider than the wedge angle of the tip wedge portion 55 of the receiver. The receiver 56 is inclined with the cutting edge of the tip wedge portion 55, that is, the valley of the receiver inclined triangular groove 53 as the rotation center. There is an exciter positioning step 54 on the upper surface of the detection face plate 51. The tip edge of the exciter 59 is fitted to the side where the thickness of the step becomes thinner. The receiver tilting triangular groove 53 and the exciter positioning step 54 are spaced apart from each other so that the receiver 56 and the exciter 59 do not contact each other. It is required that the relative position and angle of the receiver 56 and the exciter 59 do not change even when an ambient temperature change or external stress is applied. Therefore, a ceramic material having a low thermal expansion coefficient, a high hardness, and a high Young's modulus is used for the detection face plate 51, which is almost the same as the ferrite material used for the receiver 56 and the exciter 58. Further, the ceramic material is excellent in wear resistance even if it contacts the metal specimen and traces the surface. The relative position and angle of the receiver 56 and the exciter 58 are ensured by the ceramic detection face plate 51.

[Cement fixation]
The inclination angle 21 of the receiver is set to the primary minimum RMS inclination angle 28 for the non-magnetic stainless steel material, and the secondary minimum RMS inclination angle 29 for the aluminum material. As shown in FIG. 8, the angle-set receiver 62 is fixed by the detection face plate 64, the exciter 63 and the cement material 61. As the cement material 61, dental glass ionomer cement is used. Dental glass ionomer cement has a thermal expansion coefficient that is almost the same as that of ceramic materials and ferrite materials, and has a high hardness after curing. Therefore, the relative relationship between the receiver and the exciter against changes in ambient temperature and application of external stress. The target position and angle can be saved. In addition, since the volume change during solidification is small, the inclination angle of the receiver before and after fixing can be kept constant, and the quality is stabilized. Furthermore, since the curing time is short, the production time is shortened. A general composition of dental glass ionomer cement is mainly composed of powder of aluminum silicate glass and an aqueous polyacrylic acid solution.

[casing]
As shown in FIG. 9, the receiver 75 and the exciter 76 fixed to the upper surface of the detection face plate 77 with a cement material 74 are resin-sealed by vacuum molding. The receiving cable connected to the receiver 75 and the exciting cable connected to the exciter 76 pass through a common cable sheath 71. The cable sheath 71 is connected to the case 73 by a cable conduit 72 to obtain bending resistance. The thin detection face plate 77 made of a ceramic material is easily cracked against bending stress. By thickening the resin on the upper surface of the detection face plate 77, bending stress is not applied to the detection face plate 17.

1) An exciter and a receiver are brought close to or in contact with a metal specimen, an eddy current is induced in the metal specimen by a primary magnetic field generated from the exciter, and a magnetic field change due to a secondary magnetic field generated from the eddy current is received. In a device that detects with a detector and detects flaws with a detection signal obtained from a receiver,
The exciter consists of an iron core with a portal cross-sectional shape and an exciting coil, and the iron core with a gate-shaped cross-sectional shape consists of a first leg, a second leg, and a beam part connecting both legs, and the first leg is Thinner than the second leg, the excitation coil is wound around the first leg,
When the metal sample is a non-magnetic stainless alloy material, the second current line of the exciting coil passing through the outside of the thin first leg of the iron core is the first that passes between the first leg and the second leg of the iron core. Located at a height higher than the current line and not exceeding the height of the iron core,
The receiver in which the receiving coil is wound on the tip side of the rod-shaped iron core is an angle at which the magnetic flux of the primary magnetic field is not linked in a state where there is no metal sample in a position where it does not contact outside the thick second leg of the exciter. An eddy current flaw detector characterized by being set to.

2) Bring the exciter and receiver close to or in contact with the metal specimen, induce a eddy current in the metal specimen by the primary magnetic field generated from the exciter, and receive the magnetic field change due to the secondary magnetic field generated from the eddy current In a device that detects with a detector and detects flaws with a detection signal obtained from a receiver,
The exciter is composed of an iron core having a portal cross section and an exciting coil, and the iron core having a gate cross section is composed of a first leg, a second leg, and a beam connecting the both legs. Thinner than the two legs, the excitation coil is wound around the first leg,
When the object to be metallized is an aluminum alloy material, the second current line of the exciting coil that passes outside the thin first leg of the iron core is the first current line that passes between the first leg and the second leg of the iron core. Located at the same height parallel to
A receiver with a receiving coil wound around the tip of a rod-shaped iron core makes an aluminum metal specimen with a thickness exceeding the flaw detection depth limit contact the detection surface at a position where it does not contact outside the thick second leg of the exciter. An eddy current flaw detector characterized by being set at an angle at which the combined flux linkage of the primary magnetic field and the secondary magnetic field is the smallest under the above condition.

In the eddy current flaw detector of 1) or 2) above,
Of the bar-shaped iron core of the receiver in which the receiving coil is wound around one end, the portion where the coil is not wound is adhered and fixed to the double-sided PCB substrate,
The double-sided PCB substrate has the same shape and the same position with a front surface copper foil pattern and a back surface copper foil pattern, and each pattern has a coil wire soldering land and a cable core wire soldering land,
Both ends of the coil wire of the receiving coil are soldered to the soldering land for coil wire,
A shielded twisted pair wire is used for the receiving cable, and the twisted pair wire is soldered to the soldering land for the cable core wire of each pattern.

In the eddy current flaw detector of 1) or 2) above,
A single-sided PCB board is bonded and fixed to the top of the exciter's gate-shaped cross-section iron core,
The single-sided PCB substrate has two copper foil patterns with a reduced pattern distance formed on the surface, and each pattern has a solder land for coil wire and a solder land for cable core wire,
Both ends of the coil wire of the exciting coil are soldered to the soldering land for coil wire,
A shielded twisted pair wire is used for the excitation cable, and the twisted pair wire core is soldered to the cable core wire soldering land of each pattern.

In the eddy current flaw detector of 1) or 2) above,
The lower end of the bar-shaped iron core of the receiver has a shape having a tip wedge portion, a triangular groove is dug on the upper surface of the detection face plate on which the receiver is installed, and the opening angle of the triangular groove is the wedge of the front end of the core of the receiver Wider than the wedge angle of the part,
The triangular groove on the detection surface and the leading edge of the core of the receiver are fitted together, and the trough of the triangular groove and the cutting edge of the leading edge of the core of the receiver serve as a fulcrum to determine the inclination of the receiver. It can be set to the desired angle.

In the eddy current flaw detector of 1) or 2) above,
A step is provided on the upper surface of the detection face plate on which the exciter is installed, and the iron core of the exciter is fitted to the side where the thickness of the step is reduced,
The distance from the triangular groove to the step is such that the receiver and the exciter do not contact each other.

In the eddy current flaw detector of 1) or 2) above,
A receiver and an exciter are installed on the upper surface, and a detection face plate used as a contact surface on the lower surface is made of a ceramic material.

In the eddy current flaw detector of 1) or 2) above,
The detection face plate, the receiver, and the exciter are bonded together by a dental glass ionomer cement material.

Increase the flaw detection depth and improve flaw detection sensitivity. Performance does not change even when ambient temperature changes or external stress is applied. Hard to wear even when rubbed against a metal specimen. Stable production quality and shortened production time.

[Configuration for non-magnetic stainless steel]
FIG. 1 shows the coil winding arrangement and internal structure of an exciter with a non-magnetic stainless steel material. The exciting coil 1 is wound around the first leg 4 of the iron core 2 having a gate-shaped cross section, and the width of the second leg 5 is larger than the width of the first leg 4. The first coil side 7 of the exciting coil 1 passes under the beam part 6 between the first leg part 4 and the second leg part 5, and the second coil side 8 is outside the first leg part 4. It passes through a portion that is higher than one coil side 7 and lower than the height of the iron core 2 having a gate-shaped cross section. An exciter cable connection board 3 is fixed on an iron core 2 having a gate-shaped cross section. The receiver 15 is located in front of the exciter 9, that is, on the opposite side of the second coil side 8. Due to the magnetic shield effect of the second leg portion 5 and the beam portion 6, the primary magnetic field strength is small in the space where the receiver 15 is placed.

The receiving coil 10 is wound around the lower end portion of the rod-shaped iron core 11. At the lower end of the rod-shaped iron core 11, there is a tip wedge portion 13, which allows the receiver 15 to be set as an inclination as an inclination fulcrum. The rod-shaped iron core 11 is bonded to the cable connection board 12 of the receiver at a portion where the receiving coil 10 is not wound.

On the upper surface of the detection face plate 16 made of a ceramic material, a receiver-inclined triangular groove 18 is dug and fitted with the tip wedge portion 13 of the receiver 15, while allowing the receiver 15 to tilt, The tilt fulcrum is positioned in the valley of the triangular groove 18. When the nonmagnetic stainless steel material is a metal specimen, the inclination angle 14 of the receiver is the primary minimum RMS inclination angle 28. The primary minimum RMS tilt angle 28 is an angle at which the interlinkage magnetic flux of the primary magnetic field of the receiving coil 10 becomes substantially zero. There is an exciter positioning step 19 on the upper surface of the detection face plate 16 made of ceramic material. The exciter 9 is placed on the thin side of the step 19 and the tip of the iron core 2 having a gate-shaped cross section is fitted. The position of the exciter 9 is fixed. The back surface of the detection surface plate is in contact with or rubbed with the metal sample as the detection surface 17.

As the cable connecting board 12 of the receiver, the double-sided PCB board 32 of FIG. 5 is used. The front surface copper foil pattern 34 and the back surface copper foil pattern 35 are formed in the same shape and the same position on both surfaces of the substrate so that the interlinkage magnetic flux on the substrate does not occur. Both ends of the coil wire of the receiving coil 30 are respectively soldered to the coil wire soldering lands. The receiving cable is a shielded twisted pair wire, and the core wire of the twisted pair wire is soldered to the cable core wire soldering land 37, respectively.

The exciter cable connection board 3 is the single-sided PCB board 43 shown in FIG. Two surface copper foil patterns 44 are formed on the surface of the substrate with the distance between the patterns as narrow as possible so that generation of a magnetic field from the substrate is suppressed. Both ends of the coil wire of the exciting coil 41 are soldered to the coil wire soldering land 45, respectively. The exciting cable is a shielded twisted pair wire, and the core wire of the twisted pair wire is soldered to the cable core wire soldering land 46, respectively. The position of the exciting coil in FIG. 6 is a configuration for aluminum and is different from the configuration for nonmagnetic stainless steel.

  As shown in FIG. 8, the receiver 62 tilted on the ceramic detection face plate 64 and the positioned exciter 63 are fixed by a cement material 61 made of dental glass ionomer cement. Furthermore, as shown in FIG. 9, the receiver 75 and the exciter 76 fixed on the detection face plate 77 with the cement material 74 are resin-sealed by vacuum molding. The positions of the exciting coils in FIGS. 8 and 9 are for aluminum, and are different from those for non-magnetic stainless steel.

[Configuration for aluminum]
Only the differences from the above-mentioned [Configuration for non-magnetic stainless steel] will be described.
FIG. 2 shows the coil winding arrangement and internal structure of an exciter with an aluminum material. The exciting coil 1 is wound around the first leg 4 of the iron core 2 having a gate-shaped cross section, and the width of the second leg 5 is larger than the width of the first leg 4. The first coil side 7 of the exciting coil 1 passes under the beam part 6 between the first leg part 4 and the second leg part 5, and the second coil side 8 is outside the first leg part 4. It passes through the same height in parallel with one coil side 7. An exciter cable connection board 3 is fixed on an iron core 2 having a gate-shaped cross section. The receiver 15 is located in front of the exciter 9, that is, on the opposite side of the second coil side 8. Due to the magnetic shield effect of the second leg portion 5 and the beam portion 6, the primary magnetic field strength is small in the space where the receiver 15 is placed.

The receiving coil 10 is wound around the lower end portion of the rod-shaped iron core 11. At the lower end of the rod-shaped iron core 11, there is a tip wedge portion 13, which allows the receiver 15 to be set as an inclination as an inclination fulcrum. The rod-shaped iron core 11 is bonded to the cable connection board 12 of the receiver at a portion where the receiving coil 10 is not wound.

On the upper surface of the detection face plate 16 made of a ceramic material, a receiver-inclined triangular groove 18 is dug and fitted with the tip wedge portion 13 of the receiver 15, while allowing the receiver 15 to tilt, The tilt fulcrum is fixed to the valley of the triangular groove 18. When the aluminum material is a metal sample, the inclination angle 14 of the receiver is the secondary minimum RMS inclination angle 29. The secondary minimum RMS inclination angle 29 is an angle at which the interlinkage magnetic flux of the receiving coil 10 is minimized when an aluminum material having a thickness exceeding the flaw detection depth limit is brought into contact with the detection surface 17. That is, the angle at which the primary magnetic field and the secondary magnetic field cancel each other most and the gross flux linkage is minimized. Others are the same as [Configuration for non-magnetic stainless steel].

INDUSTRIAL APPLICABILITY The present invention is used for flaw detection and inspection of a metal structure that has been used for many years and has a long service life due to the discovery of metal defects and defects in products in the metal material processing process.

Excitation coil winding arrangement and internal structure with non-magnetic stainless steel Winding arrangement and internal structure of exciting coil with aluminum material Angular characteristics of receiver with non-magnetic stainless steel Angular characteristics of receiver with aluminum material Receiver cabling Exciter cable connection Detection faceplate structure Attachment of receiver and exciter on the detection faceplate Case, resin sealed

DESCRIPTION OF SYMBOLS 1 Excitation coil, coil of exciter 2 Iron core of portal cross section, ferromagnetic iron core 3 Exciter cable connection board 4 First leg part 5 Second leg part 6 Beam part 7 First coil side, first current Line 8 Second coil side, second current line 9 Exciter 10 Receiving coil 11 Bar-shaped iron core, ferromagnetic iron core 12 Receiver cable connection board 13 Tip wedge, rotation center for tilting receiver 14 Receiver tilt angle θ
DESCRIPTION OF SYMBOLS 15 Receiver 16 Detection surface plate 17 Detection surface 18 Rotation center which inclines with the receiver's inclination triangular groove and the front-end wedge part of a receiver, and inclines a receiver 19 Exciter positioning step 21 Receiver inclination angle (theta)
22 Angle increase from primary minimum RMS tilt angle 28, detection plane and receiver coil axis more parallel 23 Decrease angle from primary minimum RMS tilt angle 28, detection plane and receiver coil axis more perpendicular 24 Primary magnetic field chain Magnetic flux component 25 Secondary magnetic field interlinkage component when metal specimen is thick 26 Secondary magnetic field interlinkage component when metal specimen is medium thickness 27 Secondary magnetic field chain when metal specimen is thin AC component 28 Primary minimum RMS tilt angle, minimum receiver electromotive force when no secondary magnetic field is present, tilt angle at which primary magnetic flux linkage is zero 29 secondary minimum RMS tilt angle, secondary magnetic field is detected Receiver's minimum electromotive force, inclination angle where the interlinkage primary magnetic field and the interlinkage secondary magnetic field cancel each other 30 Receiver coil 31 Rod-shaped iron core, ferromagnetic iron core 32 Double-sided PCB board, cable connection of receiver Substrate 33 Rotating center for tilting the device 34 Surface copper foil pattern 35 Back surface copper foil pattern 36 Soldering land for coil wire 37 Soldering land for cable core wire 41 Exciting coil, coil of exciter 42 Iron core of gate-shaped cross section, ferromagnetic iron core 43 Single-sided PCB board, board for exciter cable connection 44 Surface copper foil pattern 45 Soldering land for coil wire 46 Soldering land for cable core wire 51 Detection face plate 52 Detection face 53 Triangular groove for receiver tilting, Wedge of receiver Rotation center that fits the part and tilts the receiver 54 Exciter positioning step 55 Wedge tip of the receiver, rotating that tilts the receiver 56 Receiver 57 Excitation coil, exciter coil 58 Portal cross-sectional shape Iron core, ferromagnetic iron core 59 Exciter 61 Cement material 62 Receiver 63 Exciter 64 Detection face plate 71 Cable sheath 72 Cable conduit 73 Case, resin sealing 74 Cement material 75 Receiver 76 Exciter 77 Detection face plate

Claims (8)

An exciter and a receiver are brought close to or in contact with the metal specimen, an eddy current is induced in the metal specimen by the primary magnetic field generated from the exciter, and the change in the magnetic field due to the secondary magnetic field generated from the eddy current is detected by the receiver. In a device for detecting and flaw detection with a detection signal obtained from a receiver,
The exciter is composed of an iron core having a portal cross section and an exciting coil, and the iron core having a gate cross section is composed of a first leg, a second leg, and a beam connecting the both legs. Thinner than the two legs, the excitation coil is wound around the first leg,
When the metal sample is a non-magnetic stainless alloy material, the second current line of the exciting coil passing through the outside of the thin first leg of the iron core is the first that passes between the first leg and the second leg of the iron core. Located at a height higher than the current line and not exceeding the height of the iron core,
A receiver in which a receiving coil is wound around the tip end of a rod-shaped iron core links the magnetic flux of the primary magnetic field in the position where it does not contact the exciter outside the thick second leg of the exciter and there is no metal sample. An eddy current flaw detector set at an angle that does not intersect. An exciter and a receiver are brought close to or in contact with the metal specimen, an eddy current is induced in the metal specimen by the primary magnetic field generated from the exciter, and the change in the magnetic field due to the secondary magnetic field generated from the eddy current is detected by the receiver. In a device for detecting and flaw detection with a detection signal obtained from a receiver,
The exciter is composed of an iron core having a portal cross section and an exciting coil, and the iron core having a gate cross section is composed of a first leg, a second leg, and a beam connecting the both legs. Thinner than the two legs, the excitation coil is wound around the first leg,
When the object to be metallized is an aluminum alloy material, the second current line of the exciting coil that passes outside the thin first leg of the iron core is the first current line that passes between the first leg and the second leg of the iron core. Located at the same height parallel to
A receiver with a receiving coil wound around the tip of a rod-shaped iron core detects an aluminum metal specimen with a thickness exceeding the flaw detection depth limit at a position outside the thick second leg of the exciter and in contact with the exciter. An eddy current flaw detector characterized in that it is set at an angle at which the combined flux linkage of the primary magnetic field and the secondary magnetic field is the smallest when it is in contact with the magnetic field. The receiver's rod-shaped iron core wound around the tip on the side close to the detection surface is bonded and fixed to the double-sided PCB substrate at the portion where the coil is not wound.
The double-sided PCB substrate has the same shape and the same position with a front surface copper foil pattern and a back surface copper foil pattern, and each pattern has a coil wire soldering land and a cable core wire soldering land,
Both ends of the coil wire of the receiving coil are soldered to the soldering land for coil wire,
3. The vortex according to claim 1, wherein a shielded twisted pair wire is used for the receiving cable, and the core wire of the twisted pair wire is soldered to a soldering land for the cable core wire of each pattern. Current flaw detector. A single-sided PCB board is bonded and fixed to the top of the exciter's gate-shaped cross-section iron core,
The single-sided PCB substrate has two copper foil patterns with a reduced pattern distance formed on the surface, and each pattern has a solder land for coil wire and a solder land for cable core wire,
Both ends of the coil wire of the exciting coil are soldered to the soldering land for coil wire,
The vortex according to claim 1 or 2, wherein a shielded twisted pair wire is used as the excitation cable, and the core wire of the twisted pair wire is soldered to the cable core wire soldering land of each pattern. Current flaw detector. The lower end of the bar-shaped iron core of the receiver has a shape having a tip wedge portion, a triangular groove is dug on the upper surface of the detection face plate on which the receiver is installed, and the opening angle of the triangular groove is the wedge of the front end of the core of the receiver Wider than the wedge angle of the part,
The triangular groove on the detection surface and the leading edge of the core of the receiver are fitted together, and the trough of the triangular groove and the cutting edge of the leading edge of the core of the receiver serve as a fulcrum to determine the inclination of the receiver. The eddy current flaw detector according to claim 1, wherein the eddy current flaw detector can be set to a desired angle. A step is provided on the upper surface of the detection face plate on which the exciter is installed, and the iron core of the exciter is fitted on the side where the thickness of the step is reduced,
3. The eddy current flaw detector according to claim 1, wherein the distance from the triangular groove to the step is a distance that does not contact the receiver and the exciter. 3. The eddy current flaw detector according to claim 1, wherein a receiver and an exciter are installed on the upper surface, and a detection face plate used as a contact surface on the lower surface is made of a ceramic material.   The eddy current flaw detector according to claim 1 or 2, wherein the detection face plate, the receiver, and the exciter are bonded together by a detection face plate and a dental glass ionomer cement material.

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