JP6743197B2 - Drilling method and drilling device - Google Patents

Description

The present invention relates to an excavation method and an excavation device, which are used for excavation of a well for installing an underground heat exchanger and the like, which enables to perform ground drilling at high speed and with good energy efficiency.

Since drilling is performed at high speed, excavation is performed by applying a striking force to the drill head in addition to the rotating force. In this excavation, a hydraulic hammer is attached to the upper part of the drill head to apply a striking force to the rod via the drill head. However, in this excavation, a violent noise is generated, which deteriorates the surrounding environment and the working environment. There is.
On the other hand, drilling is performed in which the rod is oscillated in small increments by causing small vibrations in the vertical direction (excavation direction) to act on the drill head (for example, see Patent Document 1). By performing this excavation, the drilling speed can be improved.

In the case of drilling with vertical vibration, based on the theory that it is good to transfer the vibration energy to the bit with a value based on the natural frequency of the rod, conventionally, the vibration due to the harmonic of the natural frequency of the rod is also used. In order to make it possible, the rod is vibrated at a high band frequency of 50 to 160 Hz as a value based on the natural frequency of the rod.

At such a high frequency band, there is a serious problem that parts such as the rod and the driving part of the excavator are worn out. When the frequency is set high, the oscillation energy in the low frequency band becomes low as shown in FIG. 7, and there is a problem that the drilling efficiency decreases.
Further, the natural frequency of the entire length of the rod changes due to the addition of the rods as the drilling continues, but in the related art, since the rod is vibrated at a high frequency band of 50 to 160 Hz, There is a problem that we cannot respond flexibly to changes. In particular, since the natural frequency decreases as the total length of the rod increases due to the addition of rods, the frequency set in the high band is a value that is far from the natural frequency, and it is possible to drill with high efficiency and energy saving. There is a problem that the merit of frequency cannot be obtained.

JP-A-11-61802

The present invention has been made in consideration of the above conventional problems, and even when the rod total length changes due to the addition of rods, the rod frequency corresponds to the natural frequency of the rod total length over a wide range. It is an object of the present invention to provide an excavation method and an excavation device capable of performing high-efficiency drilling, saving energy, and reducing wear of parts.

The drilling method of the present invention detects the drilling depth of the drilling and calculates the total length of the rod used for drilling based on the drilling depth, and a first step of calculating the total length of the rod based on the calculated total length of the rod. A second step of calculating the natural frequency, and a third step of controlling the drill head for rotating and advancing the rod to vibrate along the drilling direction at a frequency that is an integral multiple of the natural frequency. , Are provided.

In this case, in the third step, when the natural frequency is within a predetermined range, the drill head is controlled to vibrate at the primary natural frequency of the entire rod length, and when the natural frequency is below the predetermined range, the drill head is vibrated. Is controlled so as to vibrate at the secondary natural frequency of the entire rod length.

The drilling device of the present invention is a drilling device that drills holes while replenishing rods, and includes a vibro head that vibrates a drill head that rotates and advances the rod along the drilling direction, and a rod used for drilling. Rod length calculation means for calculating the total length of the rod based on the depth of the drilled hole, frequency calculation means for calculating the natural frequency of the rod total length based on the calculated total length of the rod, and an integral multiple of the calculated natural frequency Frequency control means for driving the vibro head so that the drill head vibrates at the frequency of.

In this case, when the natural frequency is within a predetermined range, the frequency control means drives the vibro head so that the drill head vibrates at the primary natural frequency of the entire rod length, and the natural frequency is increased. Is less than a predetermined range, the vibro head is driven so that the drill head vibrates at the secondary natural frequency of the entire rod length.

According to the present invention, the frequency at the time of drilling can be made to correspond to the natural frequency of the entire length of the rod, energy saving can be performed with high efficiency, and wear of parts can be reduced.

It is a side view which shows the excavation device of one Embodiment of this invention. It is a front view showing the excavation device of one embodiment of the present invention. It is a block diagram of a component for performing main operation of an excavator. It is a block diagram explaining FIG. 3 more concretely. It is a flowchart of setting of the natural frequency of a rod, and frequency control. It is a graph which shows the excavation method of one Embodiment of this invention compared with the conventional method. It is a characteristic view which shows the relationship between the natural frequency of a rod and oscillation energy.

1 and 2 show an excavation device 1 according to an embodiment of the present invention.
The excavator 1 includes an excavator body 2 including a crawler 3, a guide cell 5 supported by the excavator body 2 via a hydraulic cylinder 4, and a drill head 6 attached to the guide cell 5 so as to be vertically movable. Equipped with. The posture of the guide cell 5 can be changed to the upright state, the inclined state, and the prone state with respect to the excavator main body 2 by expanding and contracting the hydraulic cylinder 4. A hydraulic unit 22 and a control unit 21 are mounted on the excavator body 2.

A rod 7 (see FIG. 3) used for drilling is attached to the drill head 6 to feed and rotate the rod 7. The rod 7 is attached to a drive rod 8 (see FIGS. 1 and 2) extending from the drill head 6. In the excavation device 1, drilling is continued while adding the rod 7. A bit for excavation is attached to the rod 7 at the lowermost stage. A vibro head 9 is built in the drill head 6, and the vibrating head 9 vibrates in the drilling direction (up and down) when driven. As a result, the rod 7 vibrates in the drilling direction. The vibro head 9 is provided with a member that vibrates vibration, for example, an eccentric weight, and the head 9 vibrates in the drilling direction when the eccentric weight rotates.

FIG. 3 is a block diagram showing in simplified form the components that perform the main operation of the excavator 1, and FIG. 4 is a block diagram showing the configuration of FIG. 3 more specifically.
In these drawings, reference numeral 10 is a depth detector in which a chain 13 is endlessly stretched over a pair of upper and lower sprockets 11 and 12, and the depth detector is arranged along the length direction of the guide cell 5. The vibro head 9 is connected to the chain 13 of the container 10. The depth detector 10 includes a sensor 10a (see FIG. 3) such as a rotary encoder that detects a rotation angle on one sprocket 11, and the vertical movement amount of the vibro head 9 is detected by the sensor 10a. Calculate the drilling depth.

In FIG. 3, reference numeral 14 is a rod length calculating means, which calculates the total length of the rod 7 used for excavation from the drilling depth calculated by the depth detector 10. Reference numeral 15 is a frequency calculation means, which calculates the natural frequency of the entire rod length based on the total length of the rod 7 calculated by the rod length calculation means 14. Reference numeral 16 is a vibration frequency control means for controlling the vibration of the vibro head 9. The vibration frequency control means 16 controls the driving of the vibro head 9 so that the drill head 6 vibrates at the frequency associated with the natural frequency of the entire rod length calculated by the frequency calculation means 15.
In this embodiment, when the drilling depth is within a predetermined range (for example, in the range of 30 to 70 m), if the natural frequency of the entire rod length is within the predetermined range, the drill head 6 will use the primary natural frequency of the entire rod length. The vibro head 9 is controlled to vibrate, and when the drilling depth exceeds a predetermined range (for example, 70 m) and the natural frequency of the rod total length becomes low and the natural frequency falls below the predetermined range, the rod total length The vibro head 9 is controlled so that the drill head 6 vibrates at the secondary natural frequency. By controlling the vibration of the drill head 6 via the vibro head 9 as described above, the drilling is continued while the entire length of the rod attached to the drill head 6 vibrates at the primary natural frequency or the secondary natural frequency. ..
The display means 17 in FIG. 3 is, for example, a monitor and visually displays the calculated rod length and the calculated frequency.

In FIG. 4, the vibration frequency detector 18 detects the vibration frequency of the vibro head 9 as an oscillating device. The vibration pressure detector 19 detects the operating pressure of the vibro head 9 as a vibration generator. The advancing pressure detector 20 detects the advancing pressure of the rod 7 to detect the reaction force of the ground, and the grounding state of the bit whether the bit is grounded or not grounded based on this detection. To detect. The control unit 21 receives the measurement signal and controls so as to maintain the resonance state of the vibration frequency. The hydraulic unit 22 generates an operating hydraulic pressure to the vibro head 9.

FIG. 5 shows a flowchart for setting the natural frequency of the rod 7 and controlling the frequency.
Drilling is continued while adding the rod 7. In S1, the replenishment of the next rod 7 is completed and excavation is started. In S2 subsequent to S1, the rod length calculation means 14 calculates the total length Lo of the rod 7 by the equation (1). In Formula 1, Dx is the drilling depth, and Lx is the length of one rod (for example, 3 m).
Lo=((Dx/Lx)+1)×Lx (1)

In S3, the frequency calculation means 15 calculates the natural frequency fn of the rod total length by the equation (2) based on the calculated rod total length Lo. In Expression (2), K=λn/2π, λn is a dimensionless constant determined by the excavated ground between π and π/2, and C is a propagation velocity, as described later. The propagation velocity C is a constant because the physical properties of the rod are constant.
λn is a constant that is set depending on the state of both ends of the rod 7, and is π when both ends are fixed and π/2 when only one end is fixed. When both ends are fixed, the lower end of the rod (bit) is in contact with the ground, and when fixed at one end, the lower end of the rod (bit) is away from the ground. In actual excavation, one end (upper end) of the rod is the drill head 6 The other end (lower end) is a constant between π and π/2 because the other end (lower end) is excavating while being pressed against the ground by the feeding force.
fn=(K/Lo)×C... Formula (2)

In S4, fn is compared with the frequency Fk preset in the vibro head 9, and if it is smaller than Fk, the process proceeds to S5 to set the target value fm of the vibration frequency to 2×fn, and if it is larger than Fk, S6. Then, the target value fm of the vibration frequency is set to fn.

After setting these vibration frequencies, the process proceeds to S7 and the manual switch is operated to turn on the vibration. In S8, the vibration adjusting valve is turned on to set an initial value, and in S9, the vibration frequency is measured. Then, in S10, the measured vibration frequency is compared with the target value fm, and if it is different from the set value, the control amount of the vibration adjusting valve is increased or decreased (S12).

The excavation method of the present invention includes a first step of detecting the drilling depth of the drilling and calculating the total length of the rod 7 used for the drilling based on the drilling depth, and a total rod length based on the calculated total length of the rod 7. And a third step of controlling the drill head 6 that rotates and feeds the rod 7 to vibrate along the drilling direction at a frequency that is an integral multiple of the natural frequency. , Are provided.
Then, in the third step, when the natural frequency of the rod total length is within a predetermined range, the drill head 6 is controlled to vibrate at the primary natural frequency of the rod total length so that the natural frequency of the rod total length falls within the predetermined range. When it is below, the drill head 6 is controlled to vibrate at the secondary natural frequency of the entire rod length.

FIG. 6 is a graph showing a case where the above-described excavation method of the present invention is adopted and a case where the conventional excavation method not adopted is compared. Characteristic curve A is a curve showing a change in natural frequency of the entire rod length depending on the drilling depth calculated by the procedure of FIG. 5, and characteristic curve B is a rod when the entire process is excavated by an existing high frequency excavator (150 Hz). A characteristic curve C is a curve showing a change in working time required for excavation, and a characteristic curve C is a curve showing a change in working time required for excavating one rod when excavating by the excavation method according to the embodiment of the present invention. In FIG. 6, the vertical axis on the left is the working time, the vertical axis on the right is the vibration frequency, and the horizontal axis is the drilling depth.

In the embodiment shown in the characteristic curve C of FIG. 6, the drilling is performed at the maximum frequency (66 Hz) up to the drilling depth of 30 m, and within the drilling depth range of 30 m to 70 m, the primary natural frequency of the entire rod length is set. Excavation is performed in synchronism, and at 70 m or more, excavation is performed in synchronism with the secondary natural frequency of the entire rod length. That is, up to a drilling depth of 30 m, excavation is performed at a frequency of 66 Hz, which is the natural frequency of the entire rod length, and in the subsequent 30 to 70 m range, the primary natural frequency of the rod length corresponding to the drilling depth. The vibration of the vibro head 9 is controlled so that the drill head 6 vibrates. In the range of 70 m or more, the vibration of the vibro head 9 is controlled so that the drill head 6 vibrates at the secondary natural frequency of the entire rod length corresponding to the drilling depth.
As is apparent from FIG. 6, in the excavation of this embodiment, the working time is shorter than that in the excavation by the conventional method.

In the present invention as described above, since the drill head, that is, the rod is vibrated in accordance with the natural frequency of the entire rod length, it is possible to save energy and perform rapid drilling with high efficiency. Further, since the maximum energy is oscillated in the low frequency band, the wear of the rod, the drill head, and other equipment can be suppressed.

DESCRIPTION OF SYMBOLS 1 Excavator 6 Drill head 7 Rod 9 Vibro head 10 Depth detector 14 Rod length calculation means 15 Frequency number calculation means 16 Frequency number control means

Claims (4)

A first step of detecting a hole drilling depth and calculating a total length of a rod used for the drilling based on the hole drilling depth;
A second step of calculating the natural frequency of the entire rod length based on the calculated total rod length;
A third step of controlling the drill head for rotating and advancing the rod to vibrate along the drilling direction of the rod at a frequency that is an integral multiple of the natural frequency. How to excavate. In the third step, when the natural frequency is within a predetermined range, the drill head is controlled to vibrate at a primary natural frequency of the entire length of the rod, and when the natural frequency is below a predetermined range, the drill head is controlled by the drill head. The excavation method according to claim 1, wherein the excavation method is controlled so as to vibrate at a secondary natural frequency of the entire length. A drilling device that drills while adding rods,
A vibro head that vibrates a drill head that rotates and advances the rod along the drilling direction,
Rod length calculating means for calculating the total length of the rod used for excavation based on the depth of the drilled hole,
Frequency calculating means for calculating the natural frequency of the entire rod length based on the calculated total rod length;
And a vibration frequency control means for driving the vibro head so that the drill head vibrates at a frequency that is an integral multiple of the calculated natural frequency. When the natural frequency is within a predetermined range, the frequency control means drives the vibro head so that the drill head vibrates at a primary natural frequency of the entire rod length, and the natural frequency is within a predetermined range. 4. The excavating device according to claim 3, wherein the vibro head is driven so that the drill head vibrates at a secondary natural frequency of the entire rod length when the vibro head vibrates.

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