JP6926441B2 - Ground drilling drill control method - Google Patents

Description

The present invention relates to a method for controlling a ground drilling drill when drilling the ground using a ground drilling drill provided with a drill blade that is rotated by an electric motor.

Conventionally, when drilling a concrete structure, a drilling device that stops the rotation and propulsion of the bit when the bit comes into contact with the buried object so as not to damage the buried object such as reinforcing bars arranged in the concrete. Control methods related to drilling and drilling are being studied.

For example, Patent Document 1 employs a grindstone bit having a flat tip formed in a drilling device, and by drilling concrete with the grindstone bit, it is not possible to easily drill with a grindstone bit having a flat tip. A method of determining whether to continue or stop the drilling work by capturing changes in the propulsion speed and the number of rotations when the grindstone bit comes into contact with a buried object such as a reinforcing bar or a pipe is disclosed.

The above method is an effective method when the drilling target is a material such as concrete that can be drilled in a grindstone bit having a uniform hardness and a flat tip. However, when the target of drilling is the ground, it is difficult to dig the ground with a grindstone bit, and the soil properties are not uniform in the depth direction, so buried objects such as gas pipes and water pipes. It is also difficult to distinguish between and the surrounding ground from changes in propulsion speed and rotation speed. Therefore, it is not possible to divert and use a drilling device for drilling concrete as in Patent Document 1.

Under such circumstances, for example, in Patent Document 2, a torque limiter is provided in a hydraulic motor of a mechanical excavation means for rotary excavation in the ground, and the mechanical excavation means for excavating the ground comes into contact with a buried object in the ground. A method is disclosed in which a torque limiter automatically disconnects from a hydraulic motor to stop the rotation of a mechanical excavation means when an excessive load is applied.

Japanese Unexamined Patent Publication No. 2007-69568 Japanese Unexamined Patent Publication No. 5-311966

The method of Patent Document 2 is effective when the underground buried object is made of a hard material as compared with the surrounding ground and causes an excessive load on the rotation of the mechanical excavation means. However, if the buried object is made of a material that is softer than the surrounding ground, such as PVC pipes and electric cables, the torque limiter will not operate because the load will be reduced. It will not stop, but will continue to dig and damage the buried object.

The present invention has been made in view of such a problem, and a main object thereof is that the drill blade has a foreign matter during drilling in the ground without being restricted by the soil properties of the ground to be drilled and the type of buried object. It is to provide a control method of the ground drilling drill capable of accurately detecting the contact with the ground drilling drill and stopping the operation of the ground drilling drill.

In order to achieve such an object, the control method of the ground drilling drill of the present invention is to actually measure the current supplied to the electric motor while drilling the ground with a ground drilling drill provided with a drill blade rotated by an electric motor. While continuously measuring the values, the latest measured value of the current and the control reference value were compared, and the absolute value of the difference between the control reference value and the latest actually measured value exceeded the preset maximum allowable amount. In this case, it is a control method of the ground drilling drill that stops the operation of the ground drilling drill, and the control reference value is a desired period from immediately after the operation of the motor to immediately before the latest measured value. It is characterized in that it is an average value of the measured values measured in 1. Another feature is that the average value of the measured values measured during the period selected based on the ground conditions of the drilling target area is used as the control reference value.

According to the above-described control method for the ground drilling drill of the present invention, the load acting on the drill blade for digging the ground increases or decreases for some reason, and the torque increases over time due to the change in these loads. The state of increase or decrease can be grasped by continuously measuring the measured value of the current and observing the change with time.

Therefore, by comparing the current control reference value and the latest measured value and evaluating the absolute value of the difference between the two with the maximum allowable amount, the drill blade can be used regardless of the soil properties of the surrounding ground. It is possible to accurately detect that some foreign matter other than the ground has come into contact and stop the operation of the ground drilling drill.

As a result, as the drilling of the ground progresses, the friction between the drill blade and the ground gradually increases, and even if the load acting on the drill blade increases, these changes over time are measured by measuring the current. It can be grasped by continuously measuring the value. Therefore, even if the measured value of the current becomes an excessive value due to friction with the ground, it is not erroneously determined that some foreign matter other than the ground has come into contact with the drill bit.

Therefore, for example, when a factory or facility that uses harmful substances is rebuilt and a survey hole is excavated to carry out a soil contamination survey on the site, the life buried in the site is in service. Regardless of the type of buried object, such as a flexible electric wire cable or a highly rigid sewer pipe, or the depth of the line equipment, it will be accurately detected and accidentally damaged. It is possible to safely carry out the drilling work of the ground without causing it.

In addition, in consideration of the ground conditions and site conditions of the area to be drilled, the difference between the latest measured value and the control standard value is accurately extracted from immediately after the operation of the motor to immediately before the latest measured value. By appropriately selecting the period during which it is possible, it becomes possible to accurately detect foreign substances in the ground.

According to the present invention, by continuously measuring the measured value of the electric current and observing the change with time, the drill blade is used during underground drilling without being restricted by the soil properties of the ground to be drilled and the type of buried object. It is possible to accurately detect that the body has come into contact with a foreign object and stop the operation of the ground drilling drill.

It is a figure which shows the outline of the ground drilling drill which minimizes by the control method of the ground drilling drill of this invention. It is a figure which shows the graph when the inside of the specimen A filled with sand of this invention is drilled by the ground drilling drill 1. It is a figure which shows the graph when the inside of the specimen B filled with the cement-based solidified body sand of this invention is drilled by the ground drilling drill 1. It is a figure which shows the graph when the inside of the specimen C filled with the gravel and the cement-based solidified body of this invention is drilled by the ground drilling drill 1.

The method for controlling a ground drilling drill of the present invention is a method suitable for drilling in the ground using a ground drilling drill provided with a drill blade that is rotated by an electric motor, and is a method suitable for drilling in the ground. This is a method of stopping the operation of the ground drilling drill by detecting that the drill blade has come into contact with a foreign object from the change. The control method of the ground drilling drill will be described in detail below with reference to FIGS. 1 to 4.

As shown in FIG. 1, the ground drilling drill 1 includes a drill blade 2 for drilling underground, an electric motor 3 as a drive source for rotating the drill blade 2, and a current measuring device 4. ing.

The drill bit body 2 includes a tip portion 21 formed at an acute angle so as to easily penetrate into the ground, and a main body portion 23 provided with a spiral blade on the peripheral surface from the tip portion 21 to the base end portion 22. The electric motor 3 is connected to the end 22 via the current measuring device 4.

The electric motor 3 is a so-called electric motor generally mounted on a small ground excavator or the like, as long as it can transmit a rotational force to the drill blade 2 to rotate the drill blade 2. Any of the electromagnetic motors and the like may be adopted.

As the current measuring device 4, any device such as an ammeter or a power measuring device may be adopted as long as it is a device capable of measuring at least the current supplied to the motor 3.

Further, the ground drilling drill 1 includes an elevating device 5 that movably supports the above-mentioned drill blade 2, the electric motor 3, and the current measuring device 4. The elevating device 5 includes a guide column 51 that is vertically erected, a rack 52 that is installed on the side surface of the guide column 51, and an elevating tool 53 that has a pinion (not shown) that meshes with the rack 52. The elevating device 53 is provided with a manual handle 54 capable of moving the elevating device 53 up and down along the guide column 51.

Then, the lifting tool 53 and the current measuring device 4 are connected to each other via the connecting jig 55, so that the drill bit body 2 is in a posture in which the tip portion 21 is vertically erected toward the ground and is a guide support. It is formed so as to be movable up and down along 51.

As a result, when the tip 21 of the drill blade 2 is brought into contact with the ground and the drill blade 2 is rotated by the electric motor 3, the weight of the drill blade 2 and the weight of the electric motor 3 are used as reaction forces to make the drill. The blade 2 makes a rotary drill in the ground. At this time, the excavated soil generated by the rotary excavation rises through the spiral blade provided in the main body 23 and is discharged onto the ground. As a result, the excavation hole H can be formed in the ground without using excavation water, compressed air, or the like.

By the way, it is generally widely known that when it is desired to grasp the torque of the motor 3, the current should be measured. Therefore, if the measured value of the current is continuously measured and the change with time is observed while drilling the ground with the ground drilling drill 1, the load acting on the drill blade 2 can be increased or reduced under various conditions. As a result, it is possible to grasp how the torque repeatedly increases and decreases over time.

Then, in the ground drilling drill 1, when the current becomes constant after gradually increasing or decreasing, it is caused by the fact that the soil properties in contact with the drill blade 2 change due to the progress of the ground drilling. , It can be assumed that the load acting on the drill blade 2 has changed. On the other hand, when the current suddenly increases or decreases, it acts on the drill blade 2 due to the foreign matter P, which is harder or softer than the surrounding ground, coming into contact with the tip 21 of the drill blade 2. It can be assumed that the load to be applied has changed.

Therefore, in the present embodiment, as a control method of the ground drilling drill 1, the measured value of the current is continuously measured by the current measuring device 4 while drilling the ground with the ground drilling drill 1, and the current is measured. Observe changes over time. In parallel with this, each time the latest measured value is measured, the average value of the measured values measured during the desired period from immediately after the operation of the motor 3 to immediately before the latest measured value of the current is sequentially calculated. , Update and set this as the management reference value.

In addition, regardless of changes in the control reference value, the maximum permissible amount of difference between the control reference value and the latest measured value is determined in advance. Then, each time the latest measured value is measured, the latest measured value and the control reference value are compared, and when the absolute value of the difference exceeds the maximum allowable amount, the tip portion 21 of the drill blade 2 hits the foreign matter P. It is judged that they are in contact with each other, and the operation of the ground drilling drill is stopped.

The maximum permissible amount may be determined by any means. In addition, when selecting the period for calculating the average value in order to calculate the control standard value, the latest actual measurement value and the control standard value should be considered in consideration of the ground conditions and site conditions of the drilling target area. The period during which the difference can be extracted with high accuracy may be appropriately selected. By doing so, it becomes possible to accurately detect the foreign matter P in the ground.

Specifically, when it is known in advance that the ground to be drilled has uniform soil properties in the depth direction, the latest actual measurement of the current immediately after the operation of the motor 3 is performed every time the latest actual measurement value is measured. The average value of the measured values for the entire period up to immediately before the value may be calculated. In this case, the average value may be calculated without considering the actually measured value measured from immediately after the operation of the motor 3 to the time when the ground drilling by the ground drilling drill 1 stabilizes.

On the other hand, if the ground conditions of the ground to be drilled are unknown, for example, the optimum period for calculating the average value should be set appropriately retroactively from immediately before the latest measured value while monitoring the change over time of the current. Just do it.

When implementing the control method of the ground drilling drill 1 described above, the current measuring device 4 installed in the ground drilling drill 1 and the terminal device 6 are connected by wire or wirelessly.

The terminal device 6 is an information processing device composed of hardware such as an arithmetic processing device and a storage device and software operating on the hardware, a communication device for inputting various data into the information processing device, a keyboard, and the like. It is a so-called personal computer or tablet terminal equipped with an output device including an input device and a display that outputs the result of arithmetic processing performed by the information processing device in real time.

Then, the storage device of the terminal device 6 stores the maximum permissible amount of the difference between the latest measured value of the preset current and the management reference value, and the measured value of the current measured by the ammeter is stored in the terminal device. It is stored in the storage device via the input device of 6. In addition, each time the latest measured value is measured, among the measured values of the current stored in the storage device, the measured value measured in a desired period from immediately after the operation of the motor 3 to immediately before the latest measured value of the current. Using the values, the arithmetic processing unit sequentially calculates the average value, and stores this as the management reference value in the storage device.

Then, every time the latest measured value is measured by the arithmetic processing unit, the control reference value and the latest measured value of current are compared, and if the absolute value of the difference exceeds the maximum allowable amount stored in the storage device in advance. , Issue a warning using the output device. In this way, the operator of the ground drilling drill 1 can determine whether or not to stop the operation of the ground drilling drill 1 based on the warning.

It should be noted that the drilling speed is measured at the same time as the current measurement, and the judgment as to whether or not to stop the operation of the ground drilling drill 1 is determined by the displacement (drilling depth) for each time obtained from the drilling speed. You may do it at the same time.

The results of carrying out the above-mentioned control method for the ground drilling drill 1 using a specimen in which a foreign substance P is embedded are shown below. In the present embodiment, as the foreign matter P, a cable in which a steel core material is coated with a synthetic resin coating material is adopted.

As for the specimen, the mold is filled with sand and the foreign matter P is embedded in the specimen A, and the mold is filled with the cement-based solidified body assuming the ground improvement body, and the foreign matter P is embedded in the predetermined depth. Three bodies, the test piece B and the test piece C in which the gravel and the cement-based solidified body assuming the ground improvement body were mixed and filled, and the foreign matter P was embedded at a predetermined depth, were prepared. As the foreign matter P, a cable in which a steel core material was coated with a synthetic resin coating material was adopted.

First, FIG. 2 shows a graph when the inside of the specimen A is drilled with the ground drilling drill 1 without setting the maximum allowable amount of the difference between the control reference value and the latest measured value. Looking at FIG. 2, since the inside of the mold is uniformly filled with sand in the depth direction, it can be seen that the measured current value is stable without any significant fluctuation immediately after the operation of the motor 3.

Further, the current drops sharply when the drilling time exceeds 64 s. This is because the tip portion 21 of the drill blade 2 comes into contact with the covering material of the cable, that is, the foreign matter P softer than the surrounding ground. After that, when the drilling time has passed 68 s, the current rises sharply. This is because the tip portion 21 of the drill blade 2 comes into contact with the core wire of the cable, that is, the foreign matter P that is harder than the surrounding ground. As described above, it can be seen that the measured value of the current accurately reflects the state of the ground where the drill blade 2 is drilled.

Next, the graph of the result of applying the control method of the ground drilling drill to the specimen B is shown in FIG. 3, and the graph of the result of applying the control method of the ground drilling drill to the specimen C is shown in FIG. 4, respectively. The maximum permissible amount in the difference between the control reference value and the latest measured value was set to 0.7A.

Looking at FIG. 3, since the inside of the mold is uniformly filled with the cement-based solidified material in the depth direction, the measured value of the current also shows a small change immediately after the operation of the motor 3, but there is a big change. It can be seen that it shows around 7A. Then, when the drilling time exceeded 180 s, the current dropped to about 6.4 A, and the operation of the ground drilling drill 1 stopped. In this case, although some scratches were observed on the surface of the cable, the drilling work was stopped without damaging the cable.

Looking at FIG. 4, it can be seen that the measured value of the current sometimes fluctuates greatly. This can be assumed to reflect the difference in hardness because the inside of the mold is filled with a mixture of gravel and cement-based solidified material. Then, the fluctuation of the current became larger around the drilling time of about 120 s, and the operation of the ground drilling drill 1 stopped when the measured value rose to about 7.6 A. In this case, the tip portion 21 of the drill blade 2 abuts on the gravel and stops without reaching the cable.

As described above, in the control method of the ground drilling drill 1, the load acting on the drill blade 2 for digging the ground increases or decreases for some reason, and the torque increases with time due to the change in these loads. Alternatively, the state of reduction can be grasped by continuously measuring the measured value of the current and observing the change with time. Therefore, by comparing the current control reference value and the latest measured value and evaluating the magnitude of the absolute value of the difference between the two with the maximum allowable amount, the drill blade 2 can be used regardless of the soil properties of the surrounding ground. It is possible to accurately detect that some foreign matter other than the ground has come into contact with the ground and stop the operation of the ground drilling drill 1.

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As a result, as the drilling of the ground progresses, the friction between the drill blade 2 and the ground gradually increases, and even if the load acting on the drill blade 2 becomes large, these changes with time are currented. It can be grasped by continuously measuring the measured value of. Therefore, even if the measured value of the current becomes an excessive value due to friction with the ground, it is not erroneously determined that some foreign matter other than the ground has come into contact with the drill bit body 2.

Therefore, for example, when a survey hole is excavated by the control method of the ground drilling drill 1 in order to carry out a soil contamination survey on the site by rebuilding a factory or facility using a harmful substance, the site Regardless of the type of buried object, such as a flexible electric wire cable or a rigid sewer pipe, and the depth of the in-service lifeline equipment buried inside. It is possible to safely carry out drilling work on the ground without accurately detecting it and accidentally damaging it.

The control method for the ground drilling drill of the present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the present invention.

For example, in the present embodiment, whether or not to stop the operation of the ground drilling drill 1 is determined based on the absolute value of the difference between the control reference value and the latest measured value of the current and the maximum allowable amount. It is not necessarily limited to this. For example, the positive maximum permissible amount and the negative maximum permissible amount of the difference between the control reference value and the latest measured value may be determined individually.

Further, in the present embodiment, the current measuring device 4 capable of measuring the current supplied to the motor 3 and the terminal device 6 are preferentially connected or wirelessly connected, but the present invention is not necessarily limited to this. For example, the terminal device 6 is further connected to the ground drill 1 so that the terminal device 6 can automatically control the ground drill 1, and this can be used as a control device for the ground drill 1, for example, an elevating device. Install at 5. Then, in this control device, when the absolute value of the difference between the control reference value and the latest measured value of the current exceeds the maximum allowable amount, the operation of the ground drilling drill 1 may be automatically stopped.

1 Ground drilling drill 2 Drill blade 21 Tip 22 Base end 23 Main body 3 Motor 4 Current measuring device 5 Lifting device 51 Guide support 52 Rack 53 Lifting tool 54 Manual handle 55 Connection jig 6 Terminal device H Drilling hole P Foreign matter

Claims (2)

While drilling holes in the ground with a ground drilling drill equipped with a drill blade that is rotated by an electric motor, while continuously measuring the actual measured value of the current supplied to the electric motor, the latest actual measured value and management standard of the current. Compare with the value,
A control method for a ground drilling drill that stops the operation of the ground drilling drill when the absolute value of the difference between the control reference value and the latest measured value exceeds a preset maximum allowable amount.
A control method for a ground drilling drill, wherein the control reference value is an average value of the measured values measured in a desired period from immediately after the operation of the motor to immediately before the latest measured value. .. The method for controlling a ground drill according to claim 1.
A control method for a ground drilling drill, characterized in that the average value of the measured values measured during a period selected based on the ground conditions of the drilling target area is used as the control reference value.

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