JP3859523B2 - Cleaning swivel for rotary percussion double pipe drilling rig - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning swivel for a double-pipe excavator, and more particularly to a swivel joint suitable when a down-the-hole hammer is used in combination with a rotary percussion drill.
[0002]
[Prior art]
The double-pipe excavation method using a rotary percussion drill having a hydraulic drill head can be excavated while protecting the hole wall with an outer pipe (outer rod), and thus is generalized as a method under a collapsed geological condition. However, this method has the following weak points.
[0003]
After excavating a collapsible formation, if it hits a stable hard rock layer or hard boulder, the excavation speed will decrease. In addition, with a light and small rotary percussion drill, it is difficult to obtain sufficient drilling efficiency due to insufficient power. As the drilling depth increases, the striking force of the hydraulic drill head is attenuated along the way.
[0004]
In order to compensate for such weak points, a down-the-hole hammer is attached to the tip of the inner pipe (inner rod) to generate an impact force in an auxiliary manner. In this case, the impact force by the hydraulic drill head is the inner rod. Is transmitted to the down-the-hole body through the following problems.
[0005]
A general commercially available down-the-hole hammer is not supposed to receive the impact force of the hydraulic percussion on the main body, and has a problem of strength. In order to obtain this strength, there is a method of increasing the thickness of the main body, but for example, if the thickness is increased on the outer diameter side, the clearance with the inner diameter of the outer rod decreases, which may hinder the cuttings discharge, or It needs to be combined with an outer rod that is one size larger. Further, when the wall thickness is increased on the inner diameter side, it is necessary to reduce the size of the piston that generates the striking force, and the excavation ability is reduced. Further, the hammer bit is hit by both the hydraulic drill head and the down-the-hole hammer, and it is very difficult to analyze what kind of influence is caused by hitting with different frequencies, and the prediction cannot be made.
[0006]
For this reason, in general, when double-pipe excavation by hydraulic percussion becomes difficult, the lower rod is left as a casing and the lower layer is switched to single excavation using only down-the-hole hammers, and hydraulic percussion is not activated. ing. However, the following problems arise in this case.
[0007]
Since the cleaning swivel that receives the cuttings discharged through the clearance between the outer rod and the inner rod and receives the cuttings in any direction by a hose or the like cannot be used, scattering of the cuttings cannot be avoided. Since the bit diameter of the down-the-hole hammer needs to be smaller than the inner diameter of the outer rod, an outer rod / outer bit that is one or more times larger is required in order to secure the designed finish hole diameter.
[0008]
If there is a stratum that is difficult to excavate with hydraulic percussion in the middle of the predetermined excavation depth, and there is a stratum that needs to protect the hole wall with an outer rod below, it is centered with a down-the-hole hammer and then expanded with an outer rod / outer bit. A hole is required. However, in this case, it is difficult to discharge the cuttings unless the inner rod / inner bit is reset. If the inner rod / inner bit cannot be set, it is possible that cuttings that are insufficiently discharged may cause problems such as premature wear or seizure of the outer bit. Is expensive. Also, when resetting the inner rod / inner bit, if the diameter of the core hole by the down-the-hole hammer is not sufficiently smaller than that of the inner bit, the inner rod will be blown away, causing a drilling accident such as screw disengagement or rod cutting. .
[0009]
[Problems to be solved by the invention]
The present invention has been made based on the technical background as described above, and achieves the following object.
An object of the present invention is to provide a cleaning swivel for a double-pipe excavator capable of solving various problems in a rotary percussion double-pipe excavation method using a down-the-hole hammer.
[0010]
[Means for Solving the Problems]
The present invention employs the following means in order to achieve the above object.
That is, the present invention is a cleaning swivel that connects between a drill head that generates a rotational force and a striking force and a double tube comprising an inner tube and an outer tube,
A top sub having an air flow path having a rear end connected to the drill head and having an axial portion opening at the front end and a radial portion opening at the outer periphery;
An outer rod sub, in which a rear end portion is fixed to the front end portion outer periphery of the top sub, and a hydraulic cylinder chamber is defined between the top sub and an annular partition formed in an inner periphery of the intermediate portion;
The outer rod sub is slidably inserted in the axial direction, the rear end portion is slidably fitted to the axial portion of the air flow path, the intermediate portion is slidably fitted to the annular partition portion, and An inner rod sub provided with a piston slidable in the hydraulic cylinder chamber;
Means for transmitting rotational force from the outer rod sub to the inner rod sub;
Fitted to the outer circumferences of the top sub and the outer rod sub so as to be relatively rotatable, each has an annular air chamber on the inner circumference, two annular liquid chambers and an annular cutting chamber on the inner circumference, and the annular air chamber on the outer circumference. An air inlet that communicates with the two annular liquid chambers and the annular cutting chamber, and a swivel case that has two liquid inlets and outlets, respectively.
The annular air chamber communicates with a radial portion of the air flow path, and the two front and rear annular liquid chambers communicate with the front and rear chambers of the cylinder chamber via a communication hole provided in the outer rod sub, respectively. The cutting chamber is communicated with a gap between the outer rod sub and the inner rod sub through a communication hole provided in the outer rod sub. In the cleaning swivel.
[0011]
More specifically, a small-diameter portion is formed at the rear end portion of the inner rod sub, and the small-diameter portion is slidably fitted to an axial portion of the air flow path. The means for transmitting the rotational force from the outer rod sub to the inner rod sub is a spline that is formed on the inner circumference of the outer rod sub and the outer circumference of the inner rod sub and is fitted to each other.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 is an axial sectional view showing an embodiment of a cleaning swivel (swivel joint) according to the present invention, FIG. 2 is an enlarged sectional view taken along line AA of FIG. 1, FIG. 3 is an exploded sectional view, and FIG. It is sectional drawing which shows the state connected to the hydraulic drill head. A cleaning swivel 1 according to the present invention includes a top sub 2, an outer rod sub 3, an inner rod sub 4 and a swivel case 5.
[0013]
The top sub 2 is provided with a female screw 8 at the rear end, and is coupled to the hydraulic drill head 6 via a shank rod 7 connected to the female screw 8 (see FIG. 4). Further, the top sub 2 is formed with an air flow path 9 including an axial portion 9a opened at the front end thereof and a radial portion 9b opened at the outer periphery. A step portion 10 is formed in the axial portion 9a.
[0014]
The outer rod sub 3 has a rear end portion fixed to the outer periphery of the front end portion of the top sub 2 via a screw 11. An outer rod (not shown) is connected to the front end of the outer rod sub 3 via an outer rod coupling 12. In the outer rod sub 3, an annular partition 14 is formed on the inner periphery of the intermediate portion, and a hydraulic cylinder chamber 15 is defined between the annular partition 14 and the top sub 2.
[0015]
The inner rod sub 4 is inserted into the outer rod sub 3 so as to be movable in the axial direction. A female screw 16 for connecting an inner rod (not shown) is provided at the front end of the inner rod sub 4. The inner rod sub 4 has a middle portion slidably fitted to the annular partition 14. A small diameter portion 13 is formed at the rear end portion of the inner rod sub 4, and the small diameter portion 13 is slidably fitted to the axial portion 9 a of the air flow path 9. Further, a piston 17 is provided on the outer periphery of the inner rod sub 4 so that the hydraulic cylinder chamber 15 can slide. The piston 17 divides the hydraulic cylinder chamber 15 into a front chamber 15a and a rear chamber 15b. From the above description, it is understood that the inner rod sub 4 having the piston 17 functions as a piston rod.
[0016]
As shown in FIG. 2, a female spline 18 is provided on the inner periphery of a portion of the outer rod sub 3 that defines the hydraulic cylinder chamber 15. On the other hand, a male spline 19 fitted to the female spline 18 is provided on the outer periphery of the inner rod sub 4. The height of the male spline 19 is lower than the depth of the female spline 18, and as a result, the circumferential gap formed between the male and female splines 18 and 19 is the front chamber 15a of the hydraulic cylinder chamber 15, and the hydraulic oil It becomes the passage way.
[0017]
The swivel case 5 is fitted to each outer periphery of the top sub 2 and the outer rod sub 3 so as to be relatively rotatable. A retainer ring 21 for fixing the swivel case to the top sub 2 and the outer rod sub 3 is fixed to the rear end of the swivel case 5 with screws 20. The swivel case 5 is provided with a swivel stopper 22 for preventing co-rotation (see FIG. 4).
[0018]
An annular air chamber 23, two front and rear annular oil chambers 24a and 24b, and an annular cutting chamber 25 spaced apart from each other in the axial direction are provided on the inner periphery of the swivel case 5. Further, the outer periphery of the swivel case 5 communicates with an air inlet 26 that communicates with the annular air chamber 23, two hydraulic oil inlets and outlets 27a and 27b that communicate with the two annular oil chambers 24a and 24b, respectively, and an annular cutting chamber 25. A cutting outlet 28 is provided.
[0019]
The annular air chamber 26 communicates with the radial portion 9 b of the air flow path 9. The two annular oil chambers 24a and 24b communicate with the front and rear chambers 15a and 15b of the hydraulic cylinder chamber 15 through communication holes 29a and 29b provided in the outer rod sub 3, respectively. Further, the annular cutting chamber 25 communicates with a gap 31 between the outer rod sub 3 and the inner rod sub 4 through a communication hole 30 provided in the outer rod sub 3.
[0020]
Next, the operation of the above embodiment will be described. FIG. 5 is an axial cross-sectional view showing a state where excavation is performed using a down-the-hole hammer. During excavation, the outer rod sub 3 is connected to a first casing 34 having an outer rod coupling 12, an outer rod 32, and an outer bit 33, all of which constitute an outer pipe. Also, the inner rod sub 4 is connected to an inner rod 35 and a starting rod 36 that constitute the inner pipe. Further, a down-the-hole hammer 39 having a hammer bit 38 is connected to the starting rod 36 through an adapter sub 37.
[0021]
The down-the-hole hammer 39 is well-known and will not be described in detail. However, a piston that operates with compressed air and gives a hammering force to the hammer bit 38 is built in. The hammer bit 38 is pressed against the bottom of the excavation hole to start hitting. (State of FIG. 5A). Further, when the hammer bit 38 is separated from the bottom of the drilling hole and the hammer bit 38 is lowered from the down-the-hole hammer body by a bit stroke S2, almost the entire amount of compressed air is ejected from the tip of the hammer bit 38, and this blown air causes the bottom of the drilling hole to be bottomed. The structure is such that cuttings remaining around can be effectively eliminated (flushing) (state shown in FIG. 5B).
[0022]
In the excavation state shown in FIG. 5A, hydraulic oil of a predetermined pressure is supplied from the hydraulic oil inlet / outlet 27b shown in FIG. 1 to the hydraulic cylinder rear chamber 15b through the annular oil chamber 24b and the communication hole 29b. As a result, the inner rod sub 4 moves forward in the axial direction, and the hammer bit 38 of the down-the-hole hammer 39 protrudes from the first casing 34. At this time, that is, when the inner rod sub 4 has advanced to the stroke end, the splines 18 and 19 are engaged with each other at the maximum area, and this position becomes the standard excavation position.
[0023]
During excavation, the rotational force and striking force generated by the hydraulic drill head 6 are transmitted to the top sub 2 via the shank rod 7. The rotational force and striking force transmitted to the top sub 2 propagate in order to the outer rod sub 3, the outer rod coupling 12, the outer rod 32 and the first casing 34 and are transmitted to the outer bit 33.
[0024]
On the other hand, with respect to the inner rod sub 4, the striking force is not transmitted from the top sub 2 because the inner rod sub 4 is in an advanced position separated from the top sub 2. Only the rotational force is transmitted to the inner rod sub 4 from the outer rod sub 3 via the splines 18 and 19. The rotational force transmitted to the inner rod sub 4 propagates in order to the inner rod 35, starting rod 36, adapter sub 37 and down-the-hole hammer 39 and is transmitted to the hammer bit 38.
[0025]
Also, during excavation, compressed air generated by an air compressor (not shown) is added with lubricating oil for a down-the-hole hammer by a line oil (not shown), and then enters the annular air chamber 23 via the air inlet 26 of the swivel case 5. Inflow. At that time, a small amount of fresh water may be mixed into the compressed air by a water injection pump for the purpose of preventing dust scattering.
[0026]
The compressed air further flows into the air flow path 9 and is supplied to the down-the-hole hammer 39 through each of the inner rod sub 4, the inner rod 35, the starting rod 36 and the adapter sub 37. A piston built in the down-the-hole hammer 39 is actuated by the compressed air, and a hammering force is applied to the hammer bit 38. At this time, compressed air is intermittently ejected from the tip of the hammer bit 38. This blown air passes through the gap between the outer rod 32 and the inner rod 35 in the direction opposite to that during air feeding, and reaches the gap 31 between the outer rod sub 3 and the inner rod sub 4. Further, the jet air is discharged to the outside from the cutting outlet 28 through the communication hole 30 and the annular cutting chamber 25, and the cuttings are transported and discharged to the ground by this air flow.
[0027]
As shown in FIG. 1, the small-diameter portion 13 of the inner rod sub 4 has a length that is always fitted and held to the axial portion 9a of the air flow path 9 via the seal ring 40. Even when the rod sub 4 is fully advanced (indicated by S1 in FIG. 1), the small diameter portion 13 does not come out of the axial portion 9a.
[0028]
To achieve the flushing state of FIG. 5B, hydraulic oil of a predetermined pressure is supplied from the hydraulic oil inlet / outlet 27a to the hydraulic cylinder front chamber 15a through the annular oil chamber 24a and the communication hole 29a. As a result, the inner rod sub 4 is retracted, the hammer bit 38 of the down-the-hole hammer 39 is separated from the bottom of the drilling hole, the hammer bit 38 is lowered by the bit stroke S2, and the entire amount of compressed air is ejected. This blown air flow effectively eliminates cuttings remaining at the bottom of the excavation hole, and the cuttings are transported and discharged to the ground through the same path as during excavation.
[0029]
The annular partition 14 provided in the outer rod sub 3 has an axial length longer than the stroke amount of the inner rod sub 4. For this reason, even if the dust seal 41 provided on the inner rod sub 4 is worn and cutting or mud adheres to the outer periphery of the inner rod sub 4, the inner rod sub 4 does not move directly to the stroke end. It is not drawn into the hydraulic cylinder front chamber 15a.
[0030]
According to the said embodiment, the following effects are brought about.
(1) Since the inner rod 35 is structured not to be directly hit by the hydraulic drill head at the advanced position which is the excavation position, the down-the-hole hammer attached to the inner rod tip is not hit, and special reinforcement is provided. do not need.
(2) Since the hammer bit 38 receives only the striking force by the down-the-hole hammer, it is not necessary to consider the conventional effect of receiving the striking force by a hydraulic drill head having a different frequency.
[0031]
(3) Since the inner rod sub 4 can be moved forward and backward whenever necessary by hydraulic pressure, the flushing operation can be performed without stopping the hitting of the outer rod sub by the hydraulic drill head.
(4) By making the stroke of the inner rod sub 4 sufficiently larger than the stroke required for the flushing operation, the axial front-rear positional relationship between the outer bit and the hammer bit can be finely adjusted. Excavation can be made according to the conditions.
[0032]
(5) The cleaning swivel according to the present invention has the same function as the cleaning swivel that must be used in the double pipe excavation method with a rotary percussion drill for discharging cuttings. There is no scattering.
(6) In the conventional double-pipe excavation method using a rotary percussion drill, the impact force of the hydraulic drill head is distributed and transmitted to both the outer bit and the inner bit. On the other hand, when the cleaning swivel according to the present invention is used, the striking force by the hydraulic drill head is transmitted only to the outer bit, so the excavation efficiency on the outer side is improved.
[0033]
(7) The cleaning swivel according to the present invention can be used in exchange for the cleaning swivel that is always used in the double pipe excavation method by the rotary percussion drill, and therefore the existing excavator can be used as it is.
[0034]
【The invention's effect】
As described above, according to the present invention, in the rotary percussion double pipe excavation method in which the down-the-hole hammer is attached to the tip of the inner pipe for drilling, the striking force of the drill head is not transmitted to the inner pipe. Various influences can be avoided. In addition, since the flushing operation can be performed without stopping hitting the outer pipe, excavation efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is an axial sectional view showing an embodiment of a cleaning swivel according to the present invention.
FIG. 2 is an enlarged cross-sectional view taken along line AA of FIG.
FIG. 3 is an exploded sectional view of the cleaning swivel.
FIG. 4 is a cross-sectional view showing a state where a cleaning swivel is connected to a hydraulic drill head.
FIG. 5 is an axial sectional view showing a state where excavation is performed using a down-the-hole hammer.
[Explanation of symbols]
1: Cleaning swivel 2: Top sub 3: Outer rod sub 4: Inner rod sub 5: Swivel case 6: Hydraulic drill head 7: Shank rod 9: Air channel 9a: Axial portion 9b: Radial portion 12: Outer rod Coupling 13: Small diameter portion 14: Annular partition 15: Hydraulic cylinder chamber 15a: Hydraulic cylinder front chamber 15b: Hydraulic cylinder rear chamber 17: Piston 18: Female spline 19: Male spline 23: Annular air chamber 24a: Annular oil chamber 24b : Annular oil chamber 25: annular cutting chamber 26: annular air chamber 26: air inlet 27a: hydraulic oil inlet / outlet 27b: hydraulic oil inlet / outlet 28: cuttings outlet 29a: communication hole 29b: communication hole 30: communication hole 31: Air gap 32: Outer rod 33: Outer bit 34: First casing 35: Inner rod 36: Suspension Computing rod 38: hammer bit 39: down-the-hole hammer

Claims (3)

A cleaning swivel for connecting between a drill head that generates a rotational force and a striking force and a double pipe comprising an inner pipe and an outer pipe,
A top sub having an air flow path having a rear end connected to the drill head and having an axial portion opening at the front end and a radial portion opening at the outer periphery;
An outer rod sub, in which a rear end portion is fixed to the front end portion outer periphery of the top sub, and a hydraulic cylinder chamber is defined between the top sub and an annular partition formed in an inner periphery of the intermediate portion;
The outer rod sub is slidably inserted in the axial direction, the rear end portion is slidably fitted to the axial portion of the air flow path, the intermediate portion is slidably fitted to the annular partition portion, and An inner rod sub provided with a piston slidable in the hydraulic cylinder chamber;
Means for transmitting rotational force from the outer rod sub to the inner rod sub;
Fitted to the outer circumferences of the top sub and the outer rod sub so as to be relatively rotatable, each has an annular air chamber on the inner circumference, two annular liquid chambers and an annular cutting chamber on the inner circumference, and the annular air chamber on the outer circumference. An air inlet that communicates with the two annular liquid chambers and the annular cutting chamber, and a swivel case that has two liquid inlets and outlets, respectively.
The annular air chamber communicates with a radial portion of the air flow path, and the two front and rear annular liquid chambers communicate with the front and rear chambers of the cylinder chamber via a communication hole provided in the outer rod sub, respectively. The cutting chamber is communicated with a gap between the outer rod sub and the inner rod sub through a communication hole provided in the outer rod sub. Cleaning swivel. The rotary percussion type according to claim 1, wherein a small-diameter portion is formed at a rear end portion of the inner rod sub, and the small-diameter portion is slidably fitted to an axial portion of the air flow path. Cleaning swivel for double pipe drilling rig. The means for transmitting the rotational force from the outer rod sub to the inner rod sub is a spline formed on the inner circumference of the outer rod sub and the outer circumference of the inner rod sub, respectively, and fitted to each other. A cleaning swivel for a rotary percussion double-pipe excavator according to claim 1 or 2.

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