JPH0774582B2 - Vertical building accuracy control device for excavator for reverse circulation method - Google Patents

Description

Description: [Industrial field of use] The present invention relates to a vertical erection accuracy management device for an excavator for a reverse circulation method.

[Conventional technology]

The excavator used in the reverse circulation construction method, as shown in FIG. 9 (a), has a rotary table c installed on a ground portion (for example, an upper end portion of a stand pipe a) via a support frame b. A drilling pipe e having a drill bit d at its lower end is slidably passed through the central rotary plate portion of c only vertically.
By driving the central rotary plate portion of the rotary table c with a hydraulic motor or the like provided inside the casing of the rotary table c, the drilling pipe e is rotationally driven, and the drill bit d at the tip is rotated to penetrate into the ground. Is configured to let.

Therefore, the vertical accuracy cannot be measured during excavation by attaching an inclinometer like an excavator for an underground continuous wall in which the main body does not rotate.

Therefore, conventionally, as shown in the figure, even if the excavation bit d is dug in a direction deviating from the vertical direction due to the influence of the inclination of the formation, etc., and the drilling pipe e is curved and the excavation hole f is inclined, During the excavation, this cannot be detected, and as shown in FIG. 9B, after the excavation is completed and the excavator is moved, the ultrasonic hole wall measuring instrument g is lowered into the excavation hole f, The vertical accuracy of the hole wall was measured, and it was so-called "rear management".

In addition, because of the "rearward management" as described above, sufficient vertical accuracy is required at the time of excavation of the pile holes, so that reinforcement work etc. due to misalignment of the pile core due to misalignment of verticality can be avoided. It is necessary to slow down the penetration speed of the excavation bit d in order to secure the soil, and to excavate slowly, and efficient construction according to the condition of the ground was impossible.

[Problems to be solved by the invention]

By the way, since the drilling pipe e is suspended by a winch or the like and originally designed to maintain a vertical posture by its own weight, the descending speed (penetration speed of the drill bit d)
The lower the drilling speed, especially the slower the penetration speed of the excavation bit d and the faster the rotation speed, the higher the vertical accuracy, and the faster the penetration speed and the slower the rotation speed, the stronger the influence of the inclination of the formation, etc. The pipe e easily tilts.

Therefore, even in the excavator for the reverse circulation method, the verticality can be corrected by controlling the penetration speed and the rotation speed of the excavation bit d. Therefore, if the vertical accuracy can be continuously detected during excavation, the excavation bit d By controlling the rotation speed and penetration speed to optimal values, it is possible to efficiently construct pile holes with high vertical accuracy.

In view of the above-mentioned current situation, the present invention, in the excavator for the reverse circulation construction method, by continuously measuring and managing the vertical accuracy during excavation, it is possible to improve the vertical accuracy of the pile and the construction efficiency of the reverse circulation. It is an object of the present invention to provide a vertical building accuracy control device for an excavator for the construction method.

[Means for solving problems]

The technical means taken by the present invention to achieve the above object are as follows. That is, the vertical erection accuracy control device for a reverse circulation excavator according to the present invention is a casing which is a fixed side (non-rotating) part of a rotary table for rotationally driving a drilling pipe equipped with an excavating bit at its tip. Four substantially horizontal arms are projected in a cross shape from the part, the tip ends of these arms are supported by a support frame, and a strain gauge is attached to at least two of the arms which are positioned at right angles to each other. , Means for detecting the inclination of the drilling pipe from the amount of strain of the arm caused by the inclination of the drilling pipe,
It comprises means for controlling the penetration speed of the drill bit or the penetration speed and the rotation speed based on the detection result.

[Action]

According to the above configuration, when the excavating bit is digging vertically in the ground, the drilling pipe is kept vertical, so bending force is not generated in the drilling pipe, and the rotary table is attached to the cross-shaped arm. Only a certain amount of strain is generated due to its own weight and the rotational reaction force, and the output of the strain gauge is constant (reference value).

If the digging direction of the drill bit shifts to either direction with respect to the vertical direction, bending force will be generated in the drilling pipe,
Since the drilling pipe penetrates the rotary table slidably only in the vertical direction, a strain corresponding to the bending force of the drilling pipe is generated in the cross-shaped arm.

The strain amount of this arm is output as an electric signal by a strain gauge, and the inclination amount of the drilling pipe is detected by measuring the strain amount of the arm based on this output signal.

Then, based on this detection result, the drilling pipe is controlled by controlling the penetration speed of the drill bit or the penetration speed and rotation speed so that the amount of strain of the arm becomes zero, that is, the output of the strain gauge becomes the reference value. Is corrected vertically.

Therefore, within the range where bending of the drilling pipe does not occur,
The maximum excavation capacity can be achieved within the range where the rotation speed and the penetration speed of the excavation bit can be maximized and vertical accuracy can be ensured.

〔Example〕

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

As shown in FIGS. 1 (a) and 1 (b), the stand pipe 1 which reaches below the groundwater level is driven from the surface of the earth, and the underground digging is performed using the hammer mug 2 and the like.

Thereafter, as shown in FIGS. 1 (c) to 1 (d), a drilling machine for reverse circulation method is installed, and the drilling pipe 3 is suspended and supported by a winch (not shown).
Is rotated by the rotary table 4 and lowered by its own weight to excavate the ground. The muddy water is discharged from the drill bit 5 at the tip of the drilling pipe 3 through the drilling pipe 3 and the swivel joint 6. Reference numeral 7 denotes a support frame of the rotary table 4, which is fixed on the stand pipe 1 or the mount 8.

The rotary table 4 is connected to a hydraulic pump unit (not shown), and as shown in FIGS. 2 and 3, a central rotary plate portion 5a having a square hole, and the central rotary plate portion 5a is rotationally driven. It is composed of a casing portion 5b containing a hydraulic motor.

The rotary table 4 of the drilling pipe 3
A kelly bar that is slidably fitted only in the up-down direction with the square hole of the central rotary plate portion 5a is used for the portion that is inserted into.

As shown in the drawing, four substantially horizontal angular axis arms 9a, 9b, 9c and 9d are projected in a cross shape from the outer peripheral portion of the casing portion 5b. And these arms 9a, 9b, 9
The tip side of c and 9d is supported by the support frame 7,
9a, 9b, 9c, 9d, four strain gauges Rx ₁ , Rx ₂ , Rx ₃ , Rx ₄ whose resistance value changes according to the amount of strain are attached to the surrounding four surfaces by means such as adhesion, A bridge circuit as shown in FIG. 5 is constructed.

The rotary table 4 is mounted on the support frame 7 and the arms 9a, 9b,
Since it is supported via 9c and 9d, assuming that the drilling pipe 3 is not inserted, in this state,
The cross-shaped arms 9a, 9b, 9c, and 9d have a distortion caused by the weight of the rotary table 4 and a sixth arm, as shown in FIG.
As shown in the figure (b), distortion occurs due to the rotational reaction force of the central rotating plate portion 5a. These distortions are caused by the drilling pipe 3
Occurs regardless of the degree of verticality and the strain amount is constant, the total value of the signals output from the strain gauges of all the arms 9a, 9b, 9c, 9d at this time can be used as the reference value.

When the digging advance direction of the digging bit 5 deviates in any direction with respect to the vertical line, a bending force is generated in the drilling pipe 3. Since the drilling pipe 3 penetrates the rotary table 4 slidably only in the vertical direction, one of the cross-shaped arms 9a, 9b, 9c, 9d can be mounted on the drilling pipe 3 as shown in FIG. A strain corresponding to the bending force is generated, and the strain gauges Rx ₁ , Rx ₂ , Rx ₃ , Rx _{4 of the} arms (for example, 9a and 9c) output an electric signal according to the strain amount.

Then, strain gauges Rx ₁ , R attached to all arms 9a, 9b, 9c, 9d
The total x _2, Rx _3, amount of signals output from the Rx _4, wherein the strain gauge _{Rx 1, Rx 2, Rx 3} , Rx 4, comparator 10, by measuring the detection means 12 of the amplifier 11 and the like The inclination of the drilling pipe 3 is detected.

The reference numeral 13 controls the penetration amount of the excavation bit 5 by adjusting the amount of current to the motor M _{1 of the} winch for hanging the drilling pipe by the winch control panel 14 provided with a variable resistor and the like, and the electromagnetic type flow control valve 15 Is a control means for controlling the rotation speed of the excavation bit 5 by adjusting the amount of pressure oil supplied to the hydraulic motor M ₂ of the rotary table 4 by means of the winch control panel 14 and the flow rate adjusting valve based on the detection result by the detection means 12. It is configured to output a control signal for 15.

In addition, the arm 9 is provided in two directions (X direction and Y direction) which are perpendicular to each other.
When the drilling pipe 3 bends in the X direction in the state where a, 9b, 9c, and 9d are projected, distortion occurs in the X-direction arm (for example, 9a and 9c) and the drilling pipe 3 bends in the Y direction. And the Y-direction arms (for example, 9b and 9d) are distorted, and when the drilling pipe 3 bends in the X and Y intermediate directions, the X and Y arms (9a and 9c, 9b and 9d) are distorted. Therefore, the strain gauges Rx ₁ , Rx ₂ , Rx ₃ , Rx
_Of the cross arms 9a, 9b, 9c, 9d, ₄ need only be attached to at least two arms positioned at right angles to each other, but in this embodiment, as shown in FIG. When bending force is generated in the pipe 3, the strain amounts of the arms located on the same straight line are superimposed and measured, and strain gauges are applied to all four arms 9a, 9b, 9c, 9d in order to increase the signal amount. R
x ₁ , Rx ₂ , Rx ₃ and Rx ₄ are attached.

According to the above configuration, when the excavation bit 5 is vertically excavating in the ground, the drilling pipe 3 is kept vertical, so the output of the strain gauges Rx ₁ , Rx ₂ , Rx ₃ , Rx ₄ is constant. Is.

If the digging advance direction of the excavation bit 5 deviates in any direction with respect to the vertical line, a bending force is generated in the drilling pipe 3, so that one of the arms 9a, 9b, 9c, 9d has a bending force of the drilling pipe 3. Distortion that corresponds to This strain amount is output as an electric signal by the strain gauges Rx ₁ , Rx ₂ , Rx ₃ , Rx ₄ ,
It is compared with the above-mentioned reference value in the comparator 10. If the strain amount signal is equal to or greater than the reference value, it is determined that the drilling pipe 3 is inclined, the control means 15 outputs a control signal, and the drilling bit 5 of the excavating bit 5 is controlled so that the strain amount signal becomes equal to the reference value. Control penetration speed and rotation speed. In other words, the arms 9a, 9b, 9c, 9
The excavation proceeds while automatically controlling the penetration speed and the rotation speed of the excavation bit 5 so that the strain amount of d does not change.

The rotation speed of the excavation bit 5 may be kept constant and only the penetration speed may be controlled.

〔The invention's effect〕

The present invention has the above-mentioned configuration, and since the vertical accuracy can be continuously measured and controlled during excavation of the ground by the excavator for the reverse circulation construction method, the rotation speed of the excavating bit and It is possible to efficiently construct a pile hole with high vertical accuracy by maximizing the excavation capacity within the range where the penetration speed is maximized and vertical accuracy is secured.

[Brief description of drawings]

1 to 8 show an embodiment of the present invention, and FIGS. 1 (a) to (d) are process diagrams for explaining a vertical building accuracy control device for an excavator for a reverse circulation method, FIG. 2 is a side view of the main part of the excavator for the reverse circulation method, and FIG. 3 is a plan view of the main part of the excavator of the same as above.
The figure is an enlarged view taken along the line IV-IV in Fig. 3, Fig. 5 is a circuit diagram of the strain gauge attached to each arm, and Figs. 7 is an operation diagram for explaining the distortion of the arm, FIG. 7 is an operation diagram for explaining the distortion of the arm when a bending force is generated in the drilling pipe, and FIG. Is. 9 (a) and 9 (b) are explanatory views of a conventional example. 3 ... Drilling pipe, 4 ... Rotary table,
5b ... Casing part, 9a, 9b, 9c, 9d ... Arm, 12 ...
… Sensing means, 13 …… Control means, Rx ₁ , Rx ₂ , Rx ₃ , Rx ₄ … Strain gauges.

Claims (1)

[Claims] 1. Four substantially horizontal arms are made to project in a cross shape from a casing part of a rotary table for driving a drilling pipe equipped with a drill bit at the tip, and the tip side of these arms is a support frame. Supported by,
At least two of the arms that are at right angles to each other
A strain gauge is attached to the arm of the book, and means for detecting the inclination of the drilling pipe from the amount of distortion of the arm caused by the inclination of the drilling pipe, and the penetration speed or the penetration speed of the drilling bit based on the detection result. A vertical placement accuracy control device for an excavator for a reverse circulation method, comprising: a means for controlling a rotation speed.