JP3247628B2 - Detector for cutter bit wear of shield machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting wear of a cutter bit of a shield machine, and more particularly, to a device having a simple structure.
The present invention relates to a wear detection device that is inexpensive, hardly breaks down, and can accurately detect a wear state of a cutter bit.

[0002]

2. Description of the Related Art In a shield construction method, a cutter bit 51 is attached to the front of a shield machine 50 as shown in FIG. As shown in FIG. 1, the cutter bits 51 are arranged in a row on the cutter spokes provided radially on the cutter head 52. The rotation of the cutter head 52 cuts the ground of the face at the portion of the carbide tip 56 at the tip of the cutter bit 51, and agitates the cut earth and sand and gravel to open the bulkhead 55 from the face plate opening 54.
It is designed to be taken in. Therefore, when excavating a hard gravel layer or the like, the carbide tip 56 of the cutter bit 51 may be worn or chipped early. Therefore, when excavating a long distance, it is necessary to replace the worn cutter bit 51 at an appropriate timing. Therefore, the cutter bit 51
There has been developed a cutter bit 51 wear detecting device capable of grasping the wear state of the cutter bit 51.

FIG. 11 is an explanatory view showing an example of a conventional cutter bit wear detecting device. FIG. 11A shows a state in which the three wear detection sensors 60 shown in FIG. Wear detection sensor 6
Numeral 0 denotes a U-shaped bent lead wire 62 accommodated in a cylindrical sensor container 61. A plurality of the wear detection sensors 60 are buried in predetermined positions of the cutter bit 51, and the wear detection sensors 60 are worn by an AC power source (not shown). An AC voltage is applied to the detection sensor 60. In this state, when the shield machine is excavated and the cutter bit 51 is worn to the tip of the wear detection sensor 60, the lead wire 62 in the sensor container 61 is disconnected. As a result, the sensor circuit is opened, and the AC impedance in the sensor circuit increases. Thus, the wear state of the cutter bit 51 is to be detected. Even if the disconnected lead wire 62 is immersed in muddy water or the like, the wear state of the cutter bit 51 can be accurately detected.

FIG. 12 shows a closed vessel 6 in a cutter bit 51.
5 shows a conventional example. As shown in FIG. 12, a substantially cylindrical airtight container 65 is accommodated in the cutter bit 51, and a fluid 66 at a predetermined pressure is sealed in the airtight container 65. The shield machine equipped with the cutter bit 51 is excavated. When the cutter bit 51 is worn down to the tip of the closed container 65 as shown by the two-dot chain line, a part of the closed container 65 is damaged, and the fluid 66 inside flows out to reduce the pressure in the container. This pressure drop is applied to the pressure pipe 67
Is detected by a pressure gauge (not shown) through
The purpose of this study is to grasp the wear state of the tire.

[0005]

However, in order to detect a continuous change in the amount of wear of the cutter bit 51 in the conventional example using the wear detection sensor 60 shown in FIG. Must be provided with a plurality of different wear limit points. When a plurality of detection points are provided in the cutter bit 51, there is a problem that the number of electric wires from each detection point increases and the device becomes complicated. Also, in the conventional example in which the closed container 65 shown in FIG. 12 is provided in the cutter bit 51, similarly, only one change in the amount of wear can be detected at one detection point, and the continuous change in the wear of the cutter bit 51 is not detected. For this purpose, a plurality of closed containers 65 must be provided in the cutter bit 51, which leads to a complicated device. Also, since the pressure fluid 66 flows out to the outside, sufficient consideration must be given to the fluid 66 used.

In addition, there has been proposed a method in which an ultrasonic probe, a CCD camera, or the like is mounted on the front of the cutter head and the wear state of the cutter bit is confirmed on an image obtained by a monitor or the like at the rear. However, these techniques also have a problem that the wear state of the cutter bit cannot be continuously measured or the wear state cannot be quantitatively grasped. Further, there is also a problem that the cost of the wear detection device is increased because the wear detection device to be used has a complicated structure.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to ascertain the wear of the cutter bit of the shield machine in which the change in the wear amount of the cutter bit can be grasped continuously and accurately. A detection device is provided.

[0008]

In order to achieve the above object, the present invention provides a magnetic core having a primary coil and a secondary coil wound at a predetermined position on a cutter head face plate of a shield machine. It is housed inside, a part of the magnetic core is exposed on the cutting front surface, and a wear detection head serving as a detection head portion is fixed, and an AC voltage is applied to the primary side coil to cause wear of the detection head portion. The wear amount of the detection head is detected by an output voltage of the secondary coil obtained from a changed magnetic resistance value of a magnetic circuit of the magnetic core.

A magnetic core having a coil wound therein is housed in a predetermined position of a cutter head face plate of a shield machine, and a part of the magnetic core is exposed to a cutting front surface to form a detection head. A detection head is fixed, an AC voltage is applied to the coil, and a wear amount of the detection head portion is detected by an output current obtained from a self-inductance value of the coil changed by the wear of the detection head portion. And

[0010] It is preferable that the magnetic core is provided with a non-magnetic thin layer that divides a magnetic circuit of the detection head section so as to increase the magnetic resistance of the magnetic circuit.

It is preferable that the height of the detection head is made equal to the wear limit of the cutter head.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a wear detecting device for a cutter bit of a shield machine according to the present invention will be described.
This will be described with reference to the accompanying drawings. FIG. 1 shows a shield machine 50 equipped with a wear detecting device for a cutter bit 51 according to the present invention.
FIG. 2 is a front view showing the cutter head 52 of FIG. FIG. 2 is a cross-sectional view showing a leading portion of the shield machine 50.
The shield excavator 50 shown in FIGS. 1 and 2 has the same structure as a known muddy shield excavator, and has four Katas spokes 53 arranged in a cross shape. The cutter bits 51 are arranged in a row at a predetermined interval at a longitudinal edge of each of the cut spokes 53. Each cutter bit 5
The shape of the cutter bit 51 is the same as that of the known one.
Tungsten carbide cemented carbide tips 56 are silver brazed to the tip of this material. In the present embodiment, the wear detecting heads 10 of the wear detecting device are mounted near the outer peripheral edge and almost at the middle of the span of the cut spokes 53. This wear detecting head 10 is a cut-spoke 5
3 is bolted to the face plate. Wear detection head 10
From the back of the face plate as shown in FIG.
A detection lead wire 31 extends to the control panel 30 installed behind the bulkhead 55 via one rotation axis. The control panel 30 is provided with a display section 32 for digitally displaying the wear amount of the cutter bit obtained by a known amplifier circuit, a calculation section for processing a detection signal, and a calculation section.

FIG. 3 is an enlarged view of a portion surrounded by a circle shown in FIG. The figure shows two pairs of opposed cutter bits 51.
And a wear detection head 10 are shown. In this embodiment, the cutter bit 51 is fixed to the side of the face plate 57 of the cut-spoke 53 by bolting so that the cutting edge made of the carbide bit 56 faces slightly outward as shown in FIG. I have. A rectangular parallelepiped wear detection head 10 is fixed on a face plate 57 at an intermediate position of the opposed cutter bit 51 by a plurality of fixing bolts (not shown) via a mounting flange 11.

FIG. 4 is a partially cutaway perspective view showing the inside of the wear detecting head 10 so that it can be seen. This wear detection head 10 is a wear detection head 10 of a magnetoresistive detection method described later. Wear detection head 10 shown in FIG.
Is a magnetic core 20 disposed substantially at the center, and a core holding material 1 for holding the magnetic core 20 at a predetermined position.
2 and 13 and an outer frame 14 that firmly covers the entire core holding members 12 and 13. Core holding material 12, 1
For 3, a brass material processed to a predetermined size is used.
In the present embodiment, the core holding members 12 and 13 are used as separate members for the convenience of assembly. However, it goes without saying that the core holding members 12 and 13 may be processed as an integrally formed part as long as assembly is not hindered. Absent.

FIGS. 5 and 6 are cross-sectional views showing the inside of the detection head unit 20. FIG. FIG. 7A is a schematic perspective view of the magnetic core 20. As shown in FIG. 7A, the magnetic core 20 includes a detection head 21 and a core body 22 having a substantially rectangular shape. The block-shaped detection head 21 and the core body 22 are integrally formed, but the detection head 21 is divided into two parts so as to divide the magnetic circuit formed by the detection head 21 and the core body 22. The slit 23 is provided at the position where the slit 23 is formed. A thin nonmagnetic resin film 24 is sandwiched between the slits 23. The non-magnetic resin film 24 can be adjusted so that the magnetic resistance of the magnetic circuit of the magnetic core 20 is increased. As the non-magnetic film 24, a polyester resin thin film is used. In the present embodiment, the thickness of the nonmagnetic resin film 24 is set to about 0.5 mm. As the material of the nonmagnetic resin film 24, various thermosetting resin films are suitable in addition to the polyester resin.

In the present embodiment, soft magnetic iron is used for the detection head 21 and the core body 22. As a similar magnetic core material, a silicon steel plate or the like is also a preferable material. The height h of the detection head 21 matches the wear limit of the bit,
In the present embodiment, it is set to 20 mm. An air gap is formed in the core body 22 at the boundary position with the detection head 21 by an inverted V-shaped notch 25. Thus, when the cutter bit 51 is worn beyond the wear limit, the magnetic path is reliably opened, and a remarkable change in magnetic resistance is obtained.

In the core body, as shown in FIG.
A primary coil 26 and a secondary coil 27 are formed. The primary coil 26 and the secondary coil 27 are coils in which a conductive wire is wound around the main body of the magnetic core 20. Further, as shown in FIG. 6, the periphery of the magnetic core 20 is completely covered with the core holding members 12 and 13. Furthermore, in order to firmly hold the positions of the core holding members 12 and 13, the core holding members 12 and 13 are entirely covered with an outer frame body 14. For the outer frame 14, a hollow steel material (SKC24) is used. A dummy bit 16 is fixed to the shoulder of the outer frame 14. The dummy bits 16 are set such that the detection head portion 21 wears almost equally to the amount of wear of the cutter bits 51 located at both ends of the face plate 57. As long as the material of the outer frame body 14 can maintain strength, carbon steel for general structure and mechanical structure can be appropriately selected and used. Further, an epoxy resin 15 is filled so as to close the space around the main body of the magnetic core 20 held by the core holding members 12 and 13. The lead wires of the primary coil 26 and the secondary coil 27 are led out of the face plate 57 via the mounting flange 11 as shown in FIG.

Here, the principle of an apparatus for detecting a change in magnetoresistance and detecting a wear amount based on a change in voltage thereof will be briefly described with reference to FIGS. 7A and 8A. FIG.
In the magnetic circuit shown in FIG. 7A, the output voltage Eo obtained according to the change (ΔΦ / Δt) of the magnetic flux Φ per Δt (ΔΦ / Δt) caused by the current I when the primary voltage E1 is applied to the primary coil 26 is terminated. It changes depending on the resistance Re. The output voltage Eo at this time is obtained by (Equation 1) to (Equation 5) in consideration of the magnetic circuit formed in the magnetic core 20.

[0019]

(Equation 1)

In the equation (5), when the detection head portion 21 of the magnetic core 20 is worn and the sectional area of the magnetic body and the average length of the magnetic body are changed, the magnetic resistance is changed, and the output voltage (secondary voltage) is correspondingly changed. Voltage) also changes. Therefore, by setting the relationship between the change in the output voltage (secondary voltage) and the wear amount of the cutter bit 51 in the arithmetic circuit, the cutter bit 51
Can be accurately detected. Specifically, the detection signal sent to the control panel 30 by the detection lead wire 31 is processed by an internal amplifier circuit and an arithmetic circuit, and the wear amount of the detection head 20 is digitally displayed on a display unit (not shown). Can be.

Next, a method for detecting the amount of wear based on a change in the self-inductance of the magnetic circuit will be described with reference to FIGS. 7 (b) and 8 (b). FIG. 7B is a perspective view showing an example of the magnetic core 20 in which one coil 28 is formed on a part of the magnetic core 20 to constitute a magnetic circuit. In the magnetic circuit shown in FIG.
The self-inductance of Eq. 8 can be expressed by (Equation 6) and (Equation 7).

[0022]

(Equation 2)

At this time, since the self-inductance of the coil 28 is proportional to the frequency, when a high-frequency AC power supply is used, L in the above equation is proportional to the frequency, and a large change in L can be obtained. Further, as is clear from Z = R + jωL, a change in self-inductance according to a change in frequency can be captured. Therefore, the unbalanced current is detected by a bridge circuit (not shown), and the detection signal of the unbalanced current is signal-processed by the arithmetic unit in the control panel 30, whereby the wear amount of the detection head unit 21 can be grasped. By providing an air gap at a portion exceeding the wear limit and keeping the magnetic path open, it is also possible to immediately display when the wear limit is exceeded. The magnetic circuit for calculating the self-inductance shown in FIG. 8B utilizes the remaining coils 27, 26 when one of the coils 26, 27 in FIG. It is also suitable as a preliminary circuit for handling the above.

FIG. 8C shows a circuit for detecting the amount of wear of the cutter bit 51 by detecting a change in the magnetic resistance as a change in the voltage. FIG. By providing two slits in the magnetic core 20 shown in the figure, a change in voltage between two points is obtained by one magnetic core 20, and a change in voltage between two points in one cutter bit 51 is obtained. The difference in the amount of wear can be detected. This makes it possible to detect the chipped state of the carbide tip or the cutter bit.

In the above description, an example is shown in which the detection head unit 21 is provided independently on the face plate of the cut-spoke 53 as shown in FIG. Next, an example in which the magnetic core 20 is incorporated in the cutter bit 51 will be described with reference to FIG. FIG. 9 shows a state in which a magnetic core 20 having a predetermined shape is accommodated in a cutter bit 51,
The wear amount at the tip of 0 is directly detected.

FIG. 10 shows the detection head 2 of the magnetic core 20.
1 shows an example in which 1 has a substantially cylindrical shape. In the magnetic core 20 shown in FIG.
3, the magnetic core 20 is held. However, the shape of the detection head as shown in FIG. 10 facilitates the holding of the magnetic core 20 by fitting the ring-shaped core holding material 12 therein. There is an advantage that it can be carried out.

[0027]

As is apparent from the above description, according to the present invention, the change in the wear amount of the cutter bit can be measured with high accuracy, and the timing for replacing the cutter bit can be properly grasped. . As a result, the cutter bit can be efficiently replaced, and an economic effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of a shield machine equipped with a cutter bit wear detecting device according to the present invention as viewed from the front.

FIG. 2 is a partial cross-sectional view showing an example of the arrangement of a wear detection device for a cutter bit in the shield machine shown in FIG. 1;

FIG. 3 is an enlarged front view showing the vicinity of the wear detection device shown in FIG. 1 in an enlarged manner.

FIG. 4 is a partial cross-sectional perspective view showing the inside of a wear detection head of the cutter bit wear detection device in a cutaway manner.

FIG. 5 is a cross-sectional view of the wear detection head shown in FIG. 4 taken along the line VV;

6 is a cross-sectional view of the wear detection head shown in FIG. 4, taken along the line VI-VI.

FIG. 7 is a perspective view showing the shape of a magnetic core and a coil wound around the magnetic core;

FIG. 8 is a schematic diagram schematically showing a relationship between a magnetic circuit of a magnetic core and a coil.

FIG. 9 is a partial cross-sectional view showing an embodiment in which a wear detection head is incorporated inside a cutter bit.

FIG. 10 is a perspective view showing a modification of the shape of the detection head of the magnetic core.

FIG. 11 is a perspective view and a partial sectional view showing an example of a conventional cutter bit wear detecting device.

FIG. 12 is a sectional view showing another example of a conventional cutter bit wear detecting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Abrasion detection head 20 Magnetic core 21 Detection head part 22 Core main body part 23 Slit 24 Non-magnetic resin film 26 Primary coil 27 Secondary coil 28 Coil 30 Control panel 50 Shield excavator 51 Cutter bit 52 Cutter head

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-97802 (JP, A) JP-A-51-57467 (JP, A) JP-A-3-259702 (JP, A) JP-A-2- 200996 (JP, A) Fully open Showa 64-34447 (JP, U) Fully open Showa 61-184905 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 7/00

Claims (4)

(57) [Claims] A magnetic core having a primary coil and a secondary coil wound therein is housed in a predetermined position of a cutter head face plate of a shield machine, and a part of the magnetic core is cut into a cutting front surface. And a wear detection head which is exposed to the head and fixed to the head, and an AC voltage is applied to the primary side coil to obtain a magnetic resistance value of a magnetic circuit of the magnetic core changed by the wear of the detection head. A wear detecting device for a cutter bit of a shield machine, wherein a wear amount of the detection head portion is detected based on the output voltage of the secondary coil. 2. A magnetic head on which a coil is wound is housed in a predetermined position of a cutter head face plate of a shield machine, and a part of the magnetic core is exposed on a cutting front surface to form a detection head unit. The worn wear detection head is fixed, an AC voltage is applied to the coil, and the wear amount of the detection head is detected by an output current obtained from a self-inductance value of the coil changed by the wear of the detection head. A wear detecting device for a cutter bit of a shield machine, wherein the wear is detected. 3. The magnetic core according to claim 1, wherein a non-magnetic thin layer for separating a magnetic circuit of the detection head is interposed between the magnetic core and the magnetic core to increase the magnetic resistance of the magnetic circuit. 3. A wear detecting device for a cutter bit of a shield machine according to claim 1 or 2. 4. The apparatus according to claim 1, wherein the height of the detection head is equal to a wear limit of the cutter head.
The wear detecting device for a cutter bit of a shield machine according to any one of claims 3 to 3.