JPH03241105A - Road surface cutter - Google Patents

Abstract

PURPOSE:To prevent cutting of a buried pipe by measuring a peak value of AC voltage obtained from an induced field detecting means and a phase difference between AC voltage wave forms excited in a transmitting coil and detection coil, and controlling a cutter blade based on a measured value. CONSTITUTION:A transmitting coil 2 transmits an AC field toward the road surface by supplying an AC current from a field generating means 3. After that, when the coil 2 and a detection coil 4 are moved so as to cross a metal pipe buried into the ground, the inducted magnetic field is generated in the metal pipe. Then, the magnetic field is converted into an electric signal detected by the coil 4, and it is inputted in an induced field detecting means 5. A detected voltage peak value and a phase difference between both signal wave forms are calculated by the detecting means 5 based on a signal from the coil 4 and an excitation signal of the coil 2, and a distance to the metal pipe is calculated. In addition, the detecting means 5 sends a control signal to a cutter driving control means 6 and controls a cutter blade 1 in accordance with a distance.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a cutter device for cutting asphalt, concrete, etc. on a road surface, and in particular, the present invention relates to a cutter device that cuts asphalt, concrete, etc. on a road surface, and in particular, cuts the road surface while preventing damage to metal pipes buried under the road surface. The present invention relates to a cutter device for cutting a road surface that can cut a surface.

[Conventional technology]

When laying communication cables, conduits, etc. along the road surface,
It is necessary to cut the paved roadbed with a cutter or the like. At this time, if underground gas pipes, water pipes, power pipes, communication cable pipes, etc. are located in shallow areas where the cutter blade can reach, accidents may occur in which these pipes are cut or damaged. . For this reason, the buried position of the metal pipes had to be confirmed in advance, or the pipes had to be excavated by hand. However, such advance location confirmation and manual digging work had the problem of significantly reducing construction efficiency.

To date, the following techniques have been proposed as means for preventing such cutting accidents.

■ Exploration lever method (Figure 6) In this technique, a exploration lever 62 is placed at the tip of the cutter blade 61.
is provided, converts the resistance when the exploration lever 62 comes into contact with the conduit 66 buried under the road surface 67 into an electrical signal, amplifies the signal with the amplifier 63 and inputs it to the signal analysis section 64, The pipe is detected from the change in the signal and the cutter blade rotation drive unit 65 is stopped. A buried object detection device for an excavator having the above-mentioned functions has been proposed by the present applicant as Utility Model Application No. 1983-8297.

■ Magnetic field detection method using stray current (Figure 7) In this technique, two receiving electromagnetic induction sensors 72 and 73 are installed in front of the cutter blade 71, and the stray current in the soil is used to detect the magnetic field under the road surface 79. The magnetic field (induced magnetic field) 78 induced from the buried pipe 70 is received, and the received signal is sent to the amplifier 74.
A comparator 76 compares the signals obtained from the electromagnetic induction sensors 72 and 73 and causes the cutter blade rotation drive unit 77 to stop cutting the buried pipe 70 when the buried pipe 70 is detected. . A cutter device with a buried metal object detector having the above-mentioned functions has been proposed by the present applicant as Utility Application No. 1-135855.

■ Transmission and reception method of ultrasonic waves and electromagnetic waves (Fig. 8) In this technique, an ultrasonic wave or electromagnetic wave transmitter 82 and a receiving sensor 83 are attached at a distance from each other to the tip of a cutter frame 81 for excavation. supplies power from the power source 84 to transmit ultrasonic waves or electromagnetic waves, and the cutter frame 8I
A signal propagated through the soil 89 in front and received by the reception sensor 83 is passed through an amplifier 85 and a filter circuit 86 and analyzed by a signal analysis section 87. When the buried pipe 80 is detected, the cutter blade rotation drive section to stop cutting. A face exploration device for detecting buried objects having the above functions was patented in 1986.
It has been proposed by the present applicant as No. 2-197596.

[Problem to be solved by the invention]

However, each of the above techniques has the following problems.

■ Detection lever method (Fig. 6) If the moving speed of the cutter device increases, there is a risk that the resistance of the detection lever 62 cannot be detected, and due to the structure, it is difficult to increase the detection distance of the metal pipe by lengthening the detection lever 62. .

(2) Magnetic field detection method using stray current (FIG. 7) Stray current in the soil is not constant depending on the location, causing a problem that the magnetic field excited from the buried pipe 70 cannot be received by the sensors 72 and 73.

■ Transmission and reception method of ultrasonic waves and electromagnetic waves (Fig. 8) In order to attach the transmitter 82 and the receiving sensor 83 to the excavating cutter blade 81, the shape of the transmitter 82 and the receiving sensor 83 is limited, so that the detection distance can be increased. Not being able to harvest, cutter blade 81
There is a risk that the transmitter 82 and the receiving sensor 83 will be worn out or damaged due to the rotation of the transmitter 82 and the receiving sensor 83.

The present invention has been made in order to solve the problems of the prior art described above, and it is possible to extend the detection distance to metal pipes and improve the detection accuracy so that metal pipes can be detected in any case. The object of the present invention is to provide a cutter device for cutting road surfaces that is capable of cutting a road surface.

[Means to solve the problem]

A configuration of the present invention that achieves the above object is shown in FIG.

The present invention is a cutter device that cuts a road surface along the road surface using a cutter blade 1, which applies an alternating current to a transmitting coil 2 provided near the road surface, and sends out an alternating magnetic field toward below the road surface. and an induced magnetic field detection means that detects an induced magnetic field induced by metal buried under the road surface using a detection coil 4 provided near the road surface and converts it into an electrical signal. 5, the peak value V of the AC voltage obtained from the induced magnetic field detection means 5, and the phase difference φ between the AC voltage waveforms excited by the transmitting coil 2 and the sensing coil 4, and based on this measurement value, The apparatus is characterized in that it includes a force/drift drive control means 6 for controlling the rotational drive of the cutter blade 1 by determining the presence or absence of a buried pipe in front of the cutter blade 1.

[Effect]

According to the road surface cutting cutter device of the present invention, while the cutter blade is in operation, an alternating current is applied to the transmitting coil, and an alternating current magnetic field is sent out below the road surface. When there is metal buried under the road surface, an induced current flows through the metal due to this alternating magnetic field, and the induced magnetic field induced by this induced current is detected by a detection coil installed in the cutter device and converted into a voltage signal. . Based on the peak value of the detected AC voltage and the phase difference between the AC voltage waveforms excited by the transmitting coil and the sensing coil, it is determined whether there is a buried pipe in front of the cutter blade, and the cutter device approaches the buried pipe. When this occurs, the rotational speed of the cutter blade is reduced, and when the buried pipe and the cutter blade become close to each other, the rotational drive of the cutter is stopped.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 shows a cutter device 2 for cutting road surfaces according to an embodiment of the present invention.
This shows the configuration of 0. The cutter device 20 is provided with a cutter blade 21 on the road surface 29 side, and the rotation of the cutter blade 21 is controlled by a cutter blade drive circuit 26. Note that a power source that supplies power to the cutter blade drive circuit 26 is not shown in this figure. A transmission coil 22 and a detection coil 24 are provided in front of the cutter blade 21 of the cutter device 20. The transmission coil 22 is connected to an alternating current generation circuit 23, and the detection coil 24 is connected to an amplifier 27 and a filter circuit 28. It is connected to the comparison calculation circuit 25 via the comparison calculation circuit 25.

This comparison calculation circuit 25 is also connected to an alternating current generation circuit 23 and a cutter blade drive circuit 26.

In the cutter device 20 configured as described above, the transmitting coil 22 transmits an alternating magnetic field toward the road surface 29 by continuous supply of alternating current from the alternating current generating circuit 23. The frequency of this alternating magnetic field is approximately 200 Hz to 2 kHz. If there is no metal buried under the road surface 29, the detection coil 24 will not detect anything. However, a metal pipe 30 is buried under the road surface 29 within the reach of the cutter blade (underground 5 (Jan)), and the transmitting coil 22 and detection coil 24 must cross the metal pipe 30 buried in the soil. , an eddy current is excited in the metal tube 30 by the alternating magnetic field from the transmitting coil 22, and an induced magnetic field is generated in the metal tube 30 by this eddy current.

This induced magnetic field is detected by the detection coil 24 and converted into a voltage signal, which is amplified by the amplifier 27, and then processed by the filter circuit 28 to generate a frequency noise that is an integral multiple of the commercial power supply or a frequency signal linked to the driving rotation speed of the cutter blade. The noise and the like are removed from the signal and the signal is input to the comparison calculation circuit 25. The comparison calculation circuit 25 calculates the detection voltage peak value Vp and the phase difference φ between both signal waveforms based on the electric signal from the detection coil 24 and the excitation signal of the transmission coil 22 from the AC current generation circuit 23, and calculates the detection voltage peak value Vp and the phase difference φ between both signal waveforms. Calculate the distance to the pipe 30 and calculate the force.
A control signal is sent to a cutter blade drive circuit 26 that controls the rotational drive of the cutter blade 21.

FIG. 3 is a flowchart showing the buried pipe detection operation in the comparison calculation circuit 25 of FIG.

When the cutter device for cutting the road surface starts, the steering wheel 30
In 1, first, there is the determination threshold value (■) of the detection voltage, which is predetermined depending on the thickness of the asphalt or concrete on the road surface on which the road surface cutting cutter device is used, and the soil quality. , and a determination threshold value φ for the phase difference between the transmitted and detected voltage waveforms. Set. Then, in the subsequent step 302, the amplifier 27 amplifies the
The voltage value measured by the detection coil 24 of the induced magnetic field from the metal tube 30 output from the filter circuit 28, that is, the detected voltage V, is read, and the AC transmission voltage Vs sent from the AC current generation circuit 23 to the transmission coil 22 is also read. Load.

When the detection voltage V and the AC transmission voltage Vs are read, the peak value vp of the detection voltage (■) is calculated in step 303, and in the subsequent step 304, the transmission/detection voltage waveform is calculated based on the detection voltage V and the AC transmission voltage Vs. The phase difference φ between them is calculated.

Subsequent steps 305 to 307 are for determining whether the calculated value satisfies the detection condition A (Vp≧Vo) and the detection condition B (φ≧φ.) of the buried pipe, and whether the calculated value is AnB or It is determined whether or not the condition of AUB is satisfied. If the condition is AnB, the drive of the cutter blade 21 is stopped, if it is AUB, the cutter blade 21 is decelerated, and if other than these, the cutter blade 21 is continuously driven.

In order to determine these conditions, in step 305, it is first determined whether vp≧V0, and if Vp≧V0 (
YES), the process proceeds to step 307, where Vp<V.

In the case of (NO), the process proceeds to step 306, and φ≧φ in both steps. Determine the conditions. If YES is determined in both steps 305 and 307, the above-mentioned AnB condition is met, so the process proceeds to step 310 and the drive of the cutter blade 21 is stopped. YES in step 305
However, if the result in step 307 is NO, or if the result is NO in step 305 and YES in step 306, the above-mentioned AUB condition is met, so the process proceeds to step 309 and the drive of the cutter blade 21 is reduced.

Further, if the determination is NO in both step 305 and step 306, the condition is other than that, so step 30
Step 8 continues to drive the cutter blade 21.

If the process proceeds to step 310, the cutter blade 21 has stopped, so this routine ends, but step 308
．． If the process proceeds to step 309, the cutter blade 21 is continuously driven, so the process returns to step 302 and the above-described process is repeated.

In Figure 4, as shown in Figure 5, the transmitter coil 22 is placed perpendicular to the ground, the detection coil 24 is placed parallel to the ground, and the top of a φ75 mm steel pipe buried under the ground 40 is moved in the longitudinal direction of the steel pipe. It shows the change in the peak value Vp of the detected voltage and the phase difference φ between the transmission voltage and the detected voltage when the signal is passed in the vertical direction. The transmitter coil 22 is made of copper wire with 5000 turns and has a diameter of 55 mm.

The length is 80 m, and the frequency of the alternating current transmitted from the alternating current generating circuit 23 to the transmitting coil 22 is 1.0.
2 kHz, and the detection coil 24 was made of copper wire with 2000 turns, and had dimensions of 12 mm in diameter and 40 mm in length. In addition, the soil in which the steel pipes were buried was sand.

As can be seen from FIG. 4, the voltage peak value vp and the phase difference φ take a maximum value immediately below the buried steel pipe, and decrease as the distance from this position increases. In this way, the detection voltage peak value v
Since p and phase difference φ gradually increase from 0 as one approaches the buried position of the pipe, it is possible to detect a steel pipe line within 40 ann from the buried position, taking into account measurement variations.

Therefore, in this case■. =5μV φ. = 5°, the existence of a steel pipe buried underground can be detected at a position 40 cm away from the position directly above it, and the drive of the cutter blade 21 can be set to the distance from the steel pipe. It can be stopped or decelerated accordingly.

In this way, the cutter device for road surface cutting of the present invention can automatically detect the position of the metal pipe buried underground in front of the cutter blade, which eliminates the need for cutting while moving it manually. It is possible to prevent cutting accidents of buried pipes that occur during excavation work on the road surface. Furthermore, until now cutting work on the road surface near buried pipes required the dispatch of personnel to attend, but with the device of the present invention, the position of steel pipes can be accurately detected, reducing the amount of work required for this work. can be reduced.

〔Effect of the invention〕

As explained above, according to the cutter device for cutting road surfaces of the present invention, it is possible to automatically detect the position of the metal pipe buried underground in front of the cutter blade. This has the effect of preventing cutting accidents of buried pipes that occur during excavation work.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle configuration of a cutter device for cutting road surfaces according to the present invention, FIG. 2 is a diagram showing the configuration of a cutter device for cutting road surfaces according to an embodiment of the present invention, and FIG. 3 is an operation of the comparison calculation circuit shown in FIG. 2. FIG. 4 is a characteristic diagram showing the relationship between the sensor position, the detected voltage peak value, and the phase difference between the detected voltage and the transmitted voltage when the metal pipe is buried in a predetermined position under the ground. The figure is an explanatory diagram explaining the positional relationship of the metal tube, transmitting coil, and detection coil in Figure 4, Figure 6 is a configuration diagram of a cutter device equipped with a conventional buried object detection device equipped with a probe lever, and Figure 7 is FIG. 8 is a block diagram of a cutter device equipped with a conventional stray current-based buried metal object detector. FIG. 8 is a block diagram of a face exploration device equipped with an ultrasonic wave and electromagnetic wave transmitter/receiver. l...Cutter blade, 2...Transmission coil, 3...Magnetic field generation means, 4...Detection coil, 5...Induced magnetic field detection means, 6...Cutter drive control means, 20. ... Cutter device, 21 ... Cutter blade, 22 ... Transmission coil, 23 ... AC current generation circuit, 24 ... Detection coil, 25 ... Comparison calculation circuit, 26 ... Cutter blade drive circuit, 27... amplifier, 28...-filter circuit, 29... road surface, 30... metal tube,

Claims (1)

[Claims] A cutter device that cuts a road surface along the road surface using a cutter blade (1), which applies an alternating current to a transmitting coil (2) provided near the road surface to cut the road surface below the road surface. A magnetic field generating means (3) that sends out an alternating magnetic field toward the road surface, and a detection coil (4) installed near the road surface detects the induced magnetic field induced by metal buried under the road surface. Induced magnetic field detection means (
5), the peak value (V) of the AC voltage obtained from the induced magnetic field detection means (5), the transmitting coil (2) and the sensing coil (
4) The phase difference (φ) between the AC voltage waveforms excited is measured, and based on this measurement, it is determined whether there is a buried pipe in front of the cutter blade (1) and the rotation of the cutter blade (1) is driven. A cutter device for cutting a road surface, comprising: a cutter drive control means (6) for controlling the cutter drive control means (6).