JP2018096156A - Earth drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earth drill capable of protecting a coil spring which mitigates an impact transmitted to a kelly-bar with a simple structure and preventing a breakage of the coil spring.SOLUTION: An earth drill includes a fixed spring receiver 37 at a lower end part outer periphery of a first kelly-bar member 28 of an innermost layer, a floating spring receiver 38 loosely fitted in an outer periphery of a first kelly-bar member above a fixed spring receiver, a coil spring 40 arranged between the fixed spring receiver and the floating spring receiver and supporting a second kelly-bar which lies adjacent to the first kelly-bar via the floating spring receiver, and a protection cover 39 which is arranged around the coil spring and limits the coil spring from contracting more than a predetermined amount by abutting to the fixed spring receiver when the coil spring contracts upon receiving a compression load.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an earth drill, and more particularly, to an earth drill provided with a coil spring that reduces an impact transmitted to a kelly bar.

  An earth drill with a kelly bar suspended from a wire rope suspended from the tip of the boom that can be raised and lowered on the base machine is rotatable and can be lifted up and down. In combination, a telescopic kellyba combined in a multistage telescopic type is used.

  In such a telescopic kellyba, when the kellyba is contracted, it is transmitted to the kellyba by a cushioning material comprising a coil spring interposed between the lower end portion of the innermost layer kelly bar member and the lower end portion of the adjacent kelly bar member. The impact is reduced (for example, refer to Patent Document 1).

JP 2008-106482 A

  However, during excavation work, an overload may occur in the Keriba. For example, since it is necessary to close the bottom cover of the excavation bucket after the excavation soil is discharged, the kelly bar is lowered to press the bottom cover of the excavation bucket against the ground. At this time, if the lowering speed of the Keriba is too fast, the coil spring may be fully compressed due to a large compression load from the Keriba. When such a full compression state is repeated, the coil spring is deformed or cracked, and in the worst case, there is a risk of damage.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an earth drill that can protect a coil spring that alleviates an impact transmitted to a Keriba with a simple structure and prevent breakage.

  In order to achieve the above object, an earth drill according to the present invention includes a plurality of stages of kelly bar members fitted in an extendable manner, and the innermost layer of the plurality of stages of kelly bar members hangs down from the tip side of the boom. An excavation bucket that is suspended by a rope via a swivel joint and is mounted on the lower end of the innermost layer kelly bar member by rotating the outermost layer kelly bar member of the plurality of stages of kelly bar members by a kelly bar driving device. In the earth drill for excavating the object to be excavated by rotating, a fixed spring receiver provided on the outer periphery of the lower end portion of the innermost layer kelly bar member, and on the outer periphery of the innermost layer kelly bar member above the fixed spring receiver. A loosely-fitted floating spring receiver, and the fixed spring receiver and the floating spring receiver are interposed between the inner spring layer and the innermost kelly bar portion. A coil spring that supports a kelly bar member adjacent to the coil spring, and the coil spring is brought into contact with the fixed spring receiver and the floating spring receiver when the coil spring is contracted by receiving a compression load. And a protective cover for restricting the spring from contracting beyond a predetermined amount.

  Furthermore, the earth drill according to the present invention is characterized in that the protective cover is provided in one of the fixed spring receiver and the floating spring receiver, and is formed in a cylindrical shape having a plurality of openings in a peripheral wall. .

  According to the earth drill of the present invention, even when a load that fully compresses the coil spring is generated, the coil spring contracts beyond a predetermined amount by the protective cover coming into contact with the fixed spring receiver and the idle spring receiver. Since it regulates, it can suppress that a coil spring fully compresses and a deformation | transformation, a crack, etc. generate | occur | produce. Further, since the protective cover surrounds the coil spring, even if the coil spring is damaged, it is possible to prevent the fragments of the coil spring from scattering.

  Furthermore, since the protective cover has a plurality of openings on the peripheral wall and is formed in a cylindrical shape, the state of the coil spring can be visually confirmed without being disassembled, so that the earth and sand adhering to the coil spring can be easily cleaned. The deterioration of the coil spring can be detected at an early stage, and the maintenance timing can be easily grasped.

It is a side view of the earth drill provided with the expansion-contraction type kelly bar which shows the 1st form example of this invention. It is a half cross-sectional view of the telescopic kellyba. It is a partial cross section figure of the principal part of an expansion-contraction type | formula Kellyba similarly. It is a partial cross section figure of the principal part of the expansion-contraction type | formula Kelever which shows the 2nd form example of this invention.

  FIG. 1 thru | or FIG. 3 shows the 1st example of the earth drill of this invention. As shown in FIG. 1, the base machine 12 of the earth drill 11 is provided with an upper swing body 14 rotatably on a top of a lower traveling body 13 having a crawler 13a via a swing bearing. A boom 15 is provided at the front portion of the upper swing body 14 so as to be raised and lowered, and a foldable gantry 16 is provided at the rear portion of the upper swing body 14. At the center in the width direction of the upper swing body 14 between the boom 15 and the gantry 16, a plurality of main winding ropes 17 and auxiliary winding ropes 18, which are lifting hoisting ropes, and a boom hoisting rope 19 are wound. Each winch (not shown) is arranged. A counterweight 20 is mounted on the rear end of the upper swing body 14. A driver's seat 14a and an equipment room 14b are provided on the right side of the upper swing body 14, and an engine room (not shown) containing an engine and a hydraulic pump is provided on the left side.

  Further, a top sheave 21 around which a main winding rope 17 for lifting and a supplementary winding rope 18 are wound is provided at the upper end of the boom 15, and the lower end side of the boom 15 is used for supporting the kelly bar drive device 22. An arm 23 and a plurality of cylinders 24 are attached.

  The main winding rope 17 hangs around the top sheave 21 and hangs down from the upper end of the boom 15, and suspends the kelly bar 26 through the swivel joint 25 so that it can be raised and lowered. An excavation bucket 27 is attached to the lower end portion of the kelly bar 26 that penetrates the rotation driving unit of the kelly bar driving device 22, and the main winding rope 17 is unwound from the winch while the kelly bar 26 is rotated by the kelly bar driving unit 22. Excavation work is performed with the excavation bucket 27 descending.

  As shown in FIG. 2, the kelly bar 26 includes an innermost first kelly bar member 28, a second kelly bar member 29 through which the first kelly bar member 28 is inserted, and a third kelly bar member through which the second kelly bar member 29 is inserted. 30, a telescopic type telescopic kellyba having a five-layer structure in which the fourth kelly bar member 31 through which the third kelly bar member 30 is inserted and the fifth outer kelly bar member 32 through which the fourth kelly bar member 31 is inserted are combined. It is formed so as to expand and contract according to the excavation depth.

  A plurality of engagement ribs (not shown) are provided in the circumferential direction at equal intervals in the circumferential direction on the outer peripheral surface of each of the kerber members 28 to 32, and other keriva members other than the first kerever member 28 are provided. Cylindrical guide members 29a to 32a having engagement grooves (not shown) with which the engagement ribs are slidably engaged in the axial direction are provided at the lower ends of 29 to 32, respectively. In addition, an engagement groove (not shown) is provided on the inner peripheral surface of the rotation drive unit of the kelly bar drive device 22 so that the engagement rib of the outermost fifth kelly bar member 32 is slidably engaged in the axial direction. It has been.

  The outer periphery of the upper end portion of the first kelly bar member 28 is in contact with the upper surface of a guide member 29 a provided at the lower portion of the second kelly bar member 29 so that the first kelly bar member 28 does not come down from the second kelly bar member 29. A cylindrical retaining member 34 is detachably provided by a fixing pin 34a. On the outer periphery of the retaining member 34, a cushioning material 35 slidably contacting the inner peripheral surface of the second Kelly bar member 29 is secured by a fixing bolt 35a. It is attached.

  Further, cushioning materials 29b to 31b that are in sliding contact with the inner peripheral surfaces of the respective kelly bar members 30 to 32 that are adjacent to the outside are provided on the outer periphery of the upper ends of the kelly bar members 29 to 31 except for the innermost layer and the outermost layer. 43 is provided so as to be detachable, and below the cushioning members 29b to 31b, the guide members 30a to 32a of the kelly bar members 30 to 32 adjacent to the outside are brought into contact with each other to prevent the kelly bar members 29 to 31 from falling off. Stoppers 29c to 31c are fixed to each other.

  On the other hand, flange members 29d to 31d are detachably provided below the guide members 29a to 31a by a plurality of fixing pins 44 to 46 inserted in the radial direction. The outer diameters of the flange members 29d to 31d are set to be substantially the same as the outer diameter of the outermost guide member 32a, and are formed so as to overlap each other when the kelly bar 26 is shortened.

  A swivel joint connecting portion 33 having a pin insertion hole 33a is provided at the upper end portion of the first kelly bar member 28 so that the swivel joint 25 is detachably connected by a connecting pin (not shown). In order to removably connect the excavation bucket 27 with a connecting pin (not shown), a bucket connecting portion 36 having a connecting pin insertion hole 36a is provided at the lower end portion of the.

  A ring-shaped fixed spring receiver 37 protruding in the outer peripheral direction of the first kelly bar member 28 is fixed to the lower portion of the first kelly bar member 28 and the upper portion of the bucket connecting portion 36. Is provided with a ring-shaped floating spring receiver 38 that can be loosely fitted to the outer periphery of the first kelly bar member 28 and can be brought into contact with the lower surface of the flange member 29 d of the second kelly bar member 29.

  Between the fixed spring receiver 37 and the idle spring receiver 38, a coil spring 40 having a lower end abutted on the upper surface of the fixed spring receiver 37 and an upper end abutted on the lower surface of the idle spring receiver 38 is provided on the first Kelly bar member 28. It is loosely fitted on the outer periphery.

  Further, a cylindrical protective cover 39 is fixed to the lower surface of the idle spring receiver 38 by welding. The protective cover 39 has an inner diameter that surrounds the outer periphery of the coil spring 40, and the length (height) in the vertical direction is longer than the length of the coil spring 40 in the fully compressed state, and the coil spring in the unloaded state. When the coil spring 40 is set in a shortened state and is in a normal use state in which the coil spring 40 supports the second to fifth kelly bar members 29 to 32, the upper surface of the fixed spring receiver 37 and the lower end of the protective cover 39 are set. A predetermined gap (A) is formed in (Fig. 3). A plurality of openings 39 a are provided in the peripheral wall of the protective cover 39.

  When excavating with the earth drill 11, as shown in FIG. 1, the kelly bar 26 in which the first kelly bar member 28 is suspended and rotatable about the main winding rope 17 via the swivel joint 25 is driven by the kelly bar. The main winding rope 17 is inserted into the rotation driving unit of the device 22, the rotation driving force is applied from the kelly bar driving device 22 to the fifth kelly bar member 32, and the excavation bucket 27 connected to the lower end of the first kelly bar member 28 is rotated. Is excavated and the excavation bucket 27 is inserted into the ground, so that the excavation bucket 27 excavates the earth and sand.

  The rotational driving force from the kelly bar drive device 22 is transmitted from the fifth kelly bar member 32 to the first kelly bar member 28 via the fourth kelly bar member 31, the third kelly bar member 30, and the second kelly bar member 29. Rotate. Moreover, when the 1st kelly bar member 28 descend | falls by unwinding of the main winding rope 17, the 2nd kelly bar member 29-the 4th kelly bar member 31 will move below, and it will be the length corresponding to excavation depth. Automatically expands.

  When the excavated soil excavated by the excavating bucket 27 is discharged, the main winding rope 17 is rewound onto the winch to raise the first kelly bar member 28. When the first kelly bar member 28 is raised, the idle spring receiver 38 abuts against the flange member 29 d of the second kelly bar member 29. At this time, the coil spring 40 is compressed and the impact transmitted to the second kelly bar member 29 is reduced, and the second kelly bar member 29 is supported by the coil spring 40 via the idle spring receiver 38.

  Similarly, when the first Keriba member 28 is raised, the flange member 29d is moved to the flange member 30d, the flange member 30d is moved to the flange member 31d, and the flange member 31d is moved to the lower end of the fifth Keriber member 32, respectively. The impact is alleviated by the spring 40, hitting, the Keriba 26 is shortened, and the excavation bucket 27 is pulled up from the excavation hole to the ground.

  As described above, the coil spring 40 takes into account an appropriate amount of deflection so that the coil spring 40 is not completely compressed with a compressive force that reduces the impact caused by the collision between the flanges when the first Keriber member 28 is raised. Designed.

  On the other hand, after the bottom cover of the excavation bucket 27 is opened and the excavation soil in the bucket is discharged, the first kelly bar member 28 is lowered while the bottom cover is pressed against the ground, the excavation bucket 27 is lowered, and the bottom cover is removed. Perform a close operation. At this time, if the first cover is closed while the first kelly bar member 28 is rapidly lowered and the excavation bucket 27 is dropped, the coil spring 40 is supported by the second kelly bar supported via the floating spring receiver 38. The entire weight of the member 29 to the fourth kerber member 31 may act abruptly, and a load that causes the coil spring 40 to be fully compressed may act on the floating spring receiver 38.

  When such a large load is applied to the coil spring 40, the lower end of the protective cover 39 comes into contact with the upper surface of the fixed spring receiver 37 and receives the compression load of the coil spring 40 before the coil spring 40 is fully compressed. It is possible to prevent the spring 40 from being fully compressed. As a result, the coil spring 40 is prevented from being fully compressed by being contracted beyond a predetermined amount, so that fatigue of the coil spring 40 can be reduced and deformation, cracking, etc. of the coil spring 40 can be suppressed. .

  Moreover, since the protective cover 39 surrounds the outer periphery of the coil spring 40, even if the coil spring 40 is damaged, it is possible to prevent the fragments of the coil spring 40 from scattering. Further, since the protective cover 39 is provided on the lower surface of the floating spring receiver 38 and a gap (A) is formed between the lower end of the protective cover 39 and the upper surface of the fixed spring receiver 37, earth or sand or water is formed in the protective cover 39. Can be prevented from accumulating. In addition, since the plurality of openings 39a are provided in the peripheral wall of the protective cover 39, the state of the coil spring 40 can be visually confirmed from the outside without disassembling the Kelly bar 26, so that deterioration of the coil spring 40 can be detected early. You can easily grasp the maintenance time.

FIG. 4 is a partial cross-sectional view of the main part of the telescopic kelly bar showing the second embodiment of the present invention. In the following description, the same components as those shown in the first embodiment are designated by the same reference numerals, and detailed description thereof is omitted.
In this embodiment, the protective cover 51 formed in the same manner as in the first embodiment is arranged so as to surround the coil spring 40 in a state where it is placed on the upper surface of the fixed spring receiver 37. A predetermined gap (B) is formed between the lower surface of the receiver 38 and the upper end of the protective cover 51.

  As a result, when a large compressive load is applied to the coil spring 40, the lower surface of the idle spring receiver 38 comes into contact with the upper end of the protective cover 51 to receive the compressive load acting on the coil spring 40. 40 can be prevented from being fully compressed. Moreover, even if the coil spring 40 is damaged, it is possible to prevent the fragments of the coil spring 40 from being scattered, and the state of the coil spring 40 can be visually confirmed from the outside by the plurality of openings 51a provided in the peripheral wall.

  Further, since the protective cover 51 is placed on the upper surface of the fixed spring receiver 37, the labor of welding can be saved, and water or earth and sand can be removed from the inside of the protective cover 51 by lifting the protective cover 51 slightly. Can be discharged.

  DESCRIPTION OF SYMBOLS 11 ... Earth drill, 12 ... Base machine, 13 ... Lower traveling body, 13a ... Crawler, 14 ... Upper turning body, 14a ... Driver's seat, 14b ... Equipment room, 15 ... Boom, 16 ... Gantry, 17 ... Main winding rope, DESCRIPTION OF SYMBOLS 18 ... Supplementary winding rope, 19 ... Unraveling rope, 20 ... Counterweight, 21 ... Top sheave, 22 ... Kelly bar drive, 23 ... Arm, 24 ... Cylinder, 25 ... Swivel joint, 26 ... Kelly bar, 27 ... Excavation bucket, 28 ... 1st Keriba member, 29 ... 2nd Keriba member, 29a ... Guide member, 29b ... Buffer material, 29c ... Stopper, 29d ... Flange member, 30 ... 3rd Keriba member, 30a ... Guide member, 30b ... Buffer material, 30c ... Stopper, 30d ... Flange member, 31 ... Fourth Keriba member, 31a ... Guide member, 31b ... Buffer material, 31c ... Stroke 31d ... Flange member, 32 ... Fifth Keriba member, 32a ... Guide member, 33 ... Swivel joint connecting portion, 33a ... Pin insertion hole, 34 ... Stopping member, 34a ... Fixing pin, 35 ... Buffer material, 35a ... Fixed Bolt 36 ... Bucket connecting part 36a ... Connecting pin insertion hole 37 ... Fixed spring receiver 38 ... Free spring receiver 39 ... Protective cover 39a ... Opening 40 ... Coil spring 41, 42, 43 ... Fixing bolt, 44, 45, 46 ... fixing pin, 51 ... protective cover, 51a ... opening

Claims (4)

  A plurality of stages of kelly bar members fitted in a telescopic manner, and the innermost layer of the plurality of stage kelly bar members is suspended via a swivel joint from a wire rope suspended from the tip side of the boom, In the earth drill in which the drilling bucket mounted on the lower end portion of the innermost layer kelly bar member is rotated and the drilling target is drilled by rotating the outermost layer kelly bar member of the kelly bar member by a kelly bar driving device. A fixed spring receiver provided on an outer periphery of a lower end portion of the innermost layer kelly bar member; a floating spring receiver that is loosely fitted on the outer periphery of the innermost layer kelly bar member above the fixed spring receiver; and the fixed spring receiver; A coil spring interposed between the floating spring receivers and supporting a kelly bar member adjacent to the innermost layer kelly bar member via the idle spring receiver; Protection that is provided around the coil spring and restricts the coil spring from contracting beyond a predetermined amount by abutting the fixed spring receiver and the floating spring receiver when the coil spring contracts under a compression load. An earth drill characterized by comprising a cover.   The earth drill according to claim 1, wherein the protective cover is formed in a cylindrical shape having a plurality of openings in a peripheral wall.   The earth drill according to claim 1 or 2, wherein the protective cover is fixed to a lower surface of the floating spring receiver.   The earth drill according to claim 1, wherein the protective cover is placed on an upper surface of the fixed spring receiver.

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