JP4471372B2 - Double pipe drilling device for small diameter - Google Patents

Description

  The present invention relates to a double-pipe drilling device that discharges flour that consists of excavated stones, excavated pieces, and the like generated by excavation to the outside via a gap between an outer tube and an inner rod.

As this type of double-pipe drilling device, a device having a relatively large bore diameter of about 120 mm is known (Patent Document 1). When used as a drilling means for a relatively large bore, the diameter of the outer tube is large, and the gap between the inner rod and the inner rod can be taken relatively easily. This is because there was no problem in discharging to the outside through the gap between the outer tube and the inner rod. However, when the diameter of the drilling hole generally used for slope stabilization construction is a small diameter of about 65 mm or less, the inner diameter of the outer tube is naturally reduced, and the rotational force and impact force against the inner bit are reduced. Since the outer diameter of the inner rod cannot be made very small for accurate transmission, the gap between the outer tube and the inner rod cannot be made sufficiently large, which hinders the smooth discharge of the flour and reduces the work efficiency. There was a technical problem such as lowering. In particular, in this type of drilling device, when the inner rod is thin and the rigidity is insufficient, there is also a troublesome problem that the middle portion is bent and the shaft center is shaken.
JP 2001-115766 A

By the way, as a result of subsequent experimental research, by changing the cross-sectional shape of the inner rod to a hexagonal shape, star shape, etc., the strength necessary to transmit the rotational force and striking force and the rigidity that can suppress the shake of the shaft center are secured. while, it is found that can enlarge the sectional area of the discharge passage of the counterbore powder, some prospects for practical use of the double pipe drilling device for small-diameter stood. Therefore, it was decided to reexamine the drill bit part. When investigating the relationship between the inner bit and the outer bit in a conventional double-pipe drilling device with a drilling diameter of 120 mm or more, the inner bit and the outer bit have the same tip position or the inner bit. Is known that protrudes from the outer bit. The protrusion amount of the conventional inner bit with respect to the outer bit was about 0.12 times the outer diameter of the outer bit (Patent Documents 1 to 3).
Japanese Patent No. 3182388 Japanese Patent No. 3382576

  The present invention has been researched and developed in view of the above-described conventional technical situation. The relationship between the inner bit and the outer bit in the double-pipe drilling device is reexamined, and the excavation performance is improved. An object of the present invention is to provide a double pipe drilling device for caliber.

In the present invention, in order to solve the above-mentioned problem, an inner rod is disposed inside the outer tube, an outer bit is provided at the tip of the outer tube, and an inner bit is provided at the tip of the inner rod, and these outer tubes It is configured to discharge the flour generated by excavation through a gap between the inner peripheral surface of the inner rod and the outer peripheral surface of the inner rod, and imparts rotational force and striking force to the inner bit via the inner rod. The outer bit of the outer bit to be excavated is a double-pipe drilling device for small diameter having an outer diameter of 65 mm or less, and the protruding amount of the inner bit with respect to the outer bit falls within the range of 0.15 to 0.32 times the outer diameter of the outer bit. The technical means of setting was adopted.

According to the present invention, the amount of protrusion of the inner bit with respect to the outer bit is set to fall within the range of 0.15 to 0.32 times the outer diameter of the outer bit. For small calibers that have less clogging and have a good excavation performance, which has been difficult when the outer diameter of the outer bit is 65 mm or less. A heavy pipe drilling device can be provided.

The present invention can be applied to a double-pipe drilling device for a small diameter in which dusting made of excavated stones or excavated pieces generated by excavation is discharged via a gap between an outer tube and an inner rod, The present invention can also be applied to a case where part of the dusting is discharged via a gap between the outer wall and the inner wall surface of the drilling hole. The present invention, drilling diameter is applied as a small-diameter below 65 m m or less. The protruding amount of the inner bit with respect to the outer bit is set so as to fall within the range of 0.15 to 0.32 times the outer diameter of the outer bit. Regarding the cross-sectional shape of the inner rod, in addition to a polygonal shape such as a hexagon, a polygonal shape that is recessed in a star shape or an arc shape is suitable. The cutout portion recessed from the circumferential surface may be formed on a straight line along the axial direction of the inner rod, or may be formed in a spiral shape. Incidentally, by supplying water or the like to the inner bit portion via the supply path inside the inner rod, the flour can be discharged in a slime form. It should be noted that a double-pipe drilling device that excavates while applying rotational force and striking force to the inner bit through at least the inner rod, as in the post-striking method in which the outer tube is driven from the rear portion shown in the following embodiments. In this case, the present invention can be applied.

  FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a partially enlarged view thereof, and FIG. 3 is an enlarged front view of the bit as viewed from the tip. As shown in the figure, the small-bore double-pipe drilling device 1 according to the present embodiment includes an inner rod 3 disposed inside a hollow cylindrical outer tube 2, and an outer tube 2 at the tip of the outer tube 2. Each of the bit 4 and the inner rod 3 is provided with an inner bit 5 at the front end portion thereof, and the outer tube 2 and the rear end portion of the inner rod 3 are fixed to the adapter 6. And excavating while adding striking force. As shown in FIG. 2, the inner bit 5 protrudes from the outer bit 4 by a protruding amount L. As shown in FIG. 3, the outer bit 4 has six excavating blades 8 and an inner bit in this embodiment. 5 has four excavating blades 9. At the intermediate position of each excavation blade 9 on the outer peripheral surface of the inner bit 5, a dust discharge groove 10 composed of a substantially V-shaped vertical groove is formed. As shown in the AA cross-sectional view of FIG. 3 shown in FIG. 4, a communication passage 12 connected to the air or water supply passage 11 formed in the inner rod 3 is opened in the middle portion of the discharge groove 10. Further, air and water are supplied to the discharge groove 10 so as to promote discharge of the flour. Incidentally, in this embodiment, the outer bit 4 and the outer tube 2, the inner bit 5 and the inner rod 3, the outer tube 2 and the rear end of the inner rod 3 and the adapter 6 are fixed by screwing means.

  FIG. 5 is an enlarged cross-sectional view taken along the line BB in FIG. As shown in the drawing, the cross-sectional shape of the inner rod 3 in the present embodiment is a hexagonal shape, and the outer peripheral surface is composed of six flat surfaces 13. These six flat surfaces 13 form six cutouts 15 that are recessed from the circumferential surface 14, and are formed between the outer circumferential surface of the inner rod 3 and the inner circumferential surface of the outer tube 2 accordingly. The cross-sectional area of the discharge path of the flouring is increased. Thus, the flour generated by excavation by the inner bit 5 and the outer bit 4 passes through the gap between the inner wall surface of the drilled hole formed by excavation from the outer peripheral portion of the outer bit 4 and the outer tube 2. It is discharged to the outside by being divided into a route and a route passing through a gap between the outer peripheral surface of the inner rod 3 and the inner peripheral surface of the outer tube 2 from the discharge groove 10 formed on the outer peripheral surface of the inner bit 5. The In this case, in relation to the geology, in the case of geology where rubble and earth and sand are mixed like the surface layer and slope of the natural ground, the inner wall surface of the hole formed by excavation tends to collapse, and the outer pipe Since the discharge path of the outer peripheral part of 2 tends to be clogged, dusting is mainly performed between the outer peripheral surface of the inner rod 3 and the inner peripheral surface of the outer tube 2 from the discharge groove 10 on the outer peripheral surface of the latter inner bit 5. It will be discharged via the gap. Note that the powdered powder that passes through the gap between the outer peripheral surface of the inner rod 3 and the inner peripheral surface of the outer tube 2 is discharged to the outside from a discharge passage 16 formed in the adapter 6. In the case of the present embodiment, the cross-sectional shape of the inner rod 3 is hexagonal, so that the cross-sectional area of the discharge channel is enlarged by the six notch circles 15, and while the hole drilling device is for small diameter, A passage cross-sectional area sufficient for discharging powder can be secured. Moreover, since it is possible to increase the height from the shaft center of the corner portion protruding on the outer peripheral surface of the inner rod 3, it is also effective for ensuring sufficient rigidity against bending and suppressing the shake of the shaft center. It is.

  Next, features of the present invention will be described. As shown in FIG. 2, the inner bit 5 protrudes from the outer bit 4 by a protruding amount L. In the present invention, the influence of the protrusion amount L of the inner bit with respect to the outer bit on the drilling performance of the small-bore double pipe drilling device was reviewed based on experiments. Table 1 shows the experimental results, and shows the experimental results when the outer diameter of the outer bit 4 is 55 mm as a small diameter double pipe drilling device. Incidentally, the same experiment was performed when the outer diameter of the outer bit 4 was 60 mm and when it was 65 mm, and the same experimental result was obtained. In this experiment, the amount of protrusion L of the inner bit with respect to the outer bit is changed for sandy soil, viscous soil, and gravel mixed soil. While actually drilling. Incidentally, the drilling conditions are strict in the order of mixed soil, cohesive soil, and sandy soil. In this drilling experiment, using two 1.5m outer pipes and two inner rods, drilling to a depth of 2.5m while connecting on the way, observing the excavation state at that time, good excavation The case of the state is indicated by ◯, the case where practical excavation is difficult is indicated by ×, and the case of excavation state which is practically not desirable is indicated by Δ.

  As is clear from the experimental results in Table 1, when the geology is sandy soil, the protrusion amount L of the inner bit with respect to the outer bit is less than 5 mm, that is, the protrusion amount L with respect to the outer diameter D of the outer bit. When the magnification L / D is less than 0.091, excavation gradually becomes difficult due to clogging of dusting, and when the protrusion amount L is 0, practical drilling becomes difficult. That is, unless the excavation speed is significantly reduced, excavation becomes difficult due to clogging of dusting. A good excavation state can be obtained when the protruding amount L of the inner bit is 5 mm (L / D = 0.091) to 15 mm (L / D = 0.273). When the projecting amount L reaches 20 mm (L / D = 0.364), the load acting during excavation, especially the frictional resistance force from the inner wall surface of the drilling hole against the outer pipe starts to increase, and the time required for drilling gradually increases. Become. When the protruding amount L is 25 mm (L / D = 0.455) or more, the tip of the inner bit is eccentric and tends to run out of the heart, and the dust is increased and clogging is likely to occur, making it difficult to rotate the bit and the outer tube. It reaches a state. As described above, when the geology is sandy soil, the inner bit protrusion amount L is in the range of 5 mm (L / D = 0.091) to 20 mm (L / D = 0.364). It is suitable as a protruding amount with respect to the outer bit in the drilling device.

  When the geology is cohesive soil, if the protruding amount L of the inner bit with respect to the outer bit is less than 5 mm (L / D = 0.091), excavation becomes difficult gradually due to clogging of the flour, and the protruding amount When L is 0, practical drilling is difficult. More specifically, excavation starts to become difficult due to clogging of dusting, etc., when the protrusion amount L of the inner bit is about 8 mm (L / D = 0.145), and the difficulty of excavation increases as the protrusion amount L further decreases. It is gradually increased. A good excavation state can be obtained when the protruding amount L of the inner bit is 8 mm (L / D = 0.145) to 15 mm (L / D = 0.273). When the protrusion amount L reaches 18 mm (L / D = 0.327), the load acting during excavation, in particular, the frictional resistance force from the inner wall surface of the drilling hole to the outer pipe starts to increase, and the time required for drilling is increased. Gradually get longer. When the protrusion L is 25 mm (L / D = 0.455) or more, the tip of the inner bit is eccentric and easily causes a runout, and more dusting occurs and clogging easily occurs, making it difficult to rotate the bit and the outer tube. It reaches a state. As described above, when the geology is cohesive soil, the range of the protrusion L of the inner bit from 8 mm (L / D = 0.145) to 18 mm (L / D = 0.327) is a double pipe cutting for small diameter. It is suitable as a protruding amount for the outer bit in the hole device.

  In the case of soil mixed with debris, almost the same experimental results were obtained as in the case of cohesive soil. That is, when the protruding amount L of the inner bit with respect to the outer bit is less than 5 mm (L / D = 0.091), excavation gradually becomes difficult due to clogging by pulverized rock fragments and the like, and the protruding amount L When the value is 0, practical drilling becomes difficult. A good excavation state is obtained when the inner bit protrusion amount L is around 8 mm (L / D = 0.145) to 15 mm (L / D = 0.273), and the protrusion amount L is 18 mm (L / D = 0.327). As a result, the load acting during excavation begins to increase, and the time required for drilling gradually increases. When the protrusion L is 25 mm (L / D = 0.455) or more, the tip of the inner bit is eccentric and the runout is caused. It is easy to occur, flouring increases, clogging is likely to occur, and it becomes difficult to rotate the bit part and the outer tube. As described above, even in the case of soil with mixed geology, the range of the inner bit protrusion amount L from 8 mm (L / D = 0.145) to 18 mm (L / D = 0.327) is a small-diameter double pipe. It is suitable as a protruding amount with respect to the outer bit in the drilling device.

  As described above, when the geology is sandy soil, the inner bit protrusion amount L is in the range of 5 mm (L / D = 0.091) to 20 mm (L / D = 0.364). It is suitable as the amount of protrusion for the outer bit in the drilling device. Similarly, when the geology is cohesive soil or mixed soil, the amount of protrusion L of the inner bit is from 8 mm (L / D = 0.145) to 18 mm (L / It was found that the range of D = 0.327) is appropriate as the protrusion amount with respect to the outer bit in the double pipe drilling device for small diameter. In the present invention, these experimental results are comprehensively judged, and the common protrusion amount L as a suitable protrusion amount range is small based on the range of 8 mm (L / D = 0.145) to 18 mm (L / D = 0.327). The appropriate amount of protrusion of the inner bit with respect to the outer bit in the double pipe drilling device for caliber is 0.15 to 0.32 times larger than the outer diameter of the outer bit in the conventional double pipe drilling device for large caliber. It was made the range.

It is the whole block diagram which showed one Example of this invention. It is the elements on larger scale of FIG. It is the enlarged front view which looked at the Example from the front of the bit. It is AA sectional drawing of FIG. It is BB expanded sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Double pipe drilling apparatus for small calibers, 2 ... Outer pipe, 3 ... Inner rod, 4 ... Outer bit, 5 ... Inner bit, 6 ... Adapter, 7 ... Drive mechanism, 8, 9 ... Excavation blade, 10 ... Discharge groove, 11 ... supply path, 12 ... communication path, 13 ... flat surface, 14 ... circumferential surface, 15 ... circular portion, 16 ... discharge path

Claims (1)

An inner rod is disposed inside the outer tube, an outer bit is provided at the tip of the outer tube, and an inner bit is provided at the tip of the inner rod, and the inner peripheral surface of the outer tube and the outer peripheral surface of the inner rod An outer diameter of the outer bit that is excavated while applying rotational force and striking force to the inner bit via the inner rod is configured to discharge the flour generated by excavation through a gap between the outer rods of 65 mm. The following small-bore double-pipe drilling device is characterized in that the protruding amount of the inner bit with respect to the outer bit is set to fall within a range of 0.15 to 0.32 times the outer diameter of the outer bit. Double pipe drilling device for small diameter.

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