Clamshell Bucket

Abstract

To provide a clamshell bucket which facilitates the repair of an abutting member.SOLUTION: A clamshell bucket 11 has: a pair of buckets 17, 21 rotatably supported on a base member 12 via support pins 20, 24 and displacing between an open position and a closed position; a base side abutting member 27 provided in the base member 12; and bucket side abutting members 32, 36 provided in the pair of buckets 17, 21, respectively. The base side abutting member 27 is composed of: a base side fixing member 28 fixed to the base member 12; and base side exchange members 29, 30 exchangeably fitted to the base side fixing member 28. The bucket side abutting members 32, 36 are composed of: bucket side fixing members 33, 37 fixed to the buckets 17, 21; and bucket side exchange members 34, 38 exchangeably fitted to the bucket side fixing members 33, 37 and abutting on the base side exchange members 29, 30.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a clamshell bucket provided on a construction machine for excavating a shaft. [Background technology]

[0002] Generally, when excavating a shaft deep underground, a shaft excavator is preferably used. The shaft excavator is configured to include a self-propelled lower traveling body, an upper rotating body rotatably mounted on the lower traveling body, and a working device provided in front of the upper rotating body. The working device includes, for example, a multi-stage telescopic arm that can be extended and retracted in the vertical direction, and a clamshell bucket provided at the tip of the arm.

[0003] The clamshell bucket includes a base member attached to the tip of the arm and a pair of buckets rotatably supported on the base member via support pins and displaceable between an open position in which they are spaced apart and a closed position in which they are close to each other. The clamshell bucket descends to the bottom of a shaft with the pair of buckets in the open position, and then excavates earth and sand by shifting the pair of buckets to the closed position. The clamshell bucket then rises from the shaft to the ground with the pair of buckets in the closed position, and discharges the excavated earth and sand into the bed of a dump truck or the like by shifting the pair of buckets to the open position above the dump truck (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-120087 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional clamshell buckets include hydraulic cylinders for opening and closing the pair of buckets, and the hydraulic cylinders operate to displace the pair of buckets between closed and open positions. Therefore, the base member and pair of buckets that make up the clamshell bucket typically have abutment members that set the amount of displacement (maximum opening) of the buckets when they move from the closed position to the open position. These abutment members are provided on the base member and the pair of buckets, respectively, and collide with each other when the pair of buckets are fully open, thereby setting the maximum opening degree and preventing the hydraulic cylinders from operating beyond an appropriate range. This prevents excessive load from being applied to the hydraulic cylinders, and the impact of the abutment members colliding with each other can be used to eject excavated material, such as soil and sand, remaining in the pair of buckets.

[0006] However, repeated collisions between the abutment members on the base member and the pair of buckets during the opening and closing operation of the clamshell bucket cause these abutment members to wear and deform. As a result, the maximum opening angle of the pair of buckets increases, and to prevent the hydraulic cylinders from operating beyond their appropriate range, the abutment members require repair depending on the degree of wear.

[0007] Contact members that have become worn or deformed are generally repaired by adding metal (build-up) using a method such as welding, followed by machining to reshape them. However, when repairing such contact members, it is necessary to shape each contact member so that the contact member on one bucket of the pair and the contact member on the base member, and the contact member on the other bucket of the pair and the contact member on the base member, come into even contact when the pair of buckets is in the open position. This poses the problem of requiring a significant amount of man-hours and skilled repair techniques to repair the contact members.

[0008] An object of the present invention is to provide a clamshell bucket in which the contact members can be easily repaired. [Means for solving the problem]

[0009] The present invention provides a clamshell bucket comprising a base member attached to the tip end of an arm constituting a working device, a pair of buckets rotatably supported on the base member via support pins and displaceable between an open position in which they are spaced apart and a closed position in which they approach each other, a base-side abutment member attached to the base member, and a bucket-side abutment member attached to each of the pair of buckets and abutting against the base-side abutment member when the pair of buckets are displaced to the open positions, wherein the base-side abutment members are made up of base-side fixed members fixed to the base member and base-side replaceable members replaceably attached to the base-side fixed members, and the bucket-side abutment members are made up of bucket-side fixed members fixed to the pair of buckets and bucket-side replaceable members replaceably attached to the bucket-side fixed members and abutting against the base-side replaceable members. The base side replacement member and the bucket side replacement member are formed using materials with different hardnesses. are. [Effects of the Invention]

[0010] According to the present invention, even if the base-side replacement member and the bucket-side replacement member repeatedly collide with each other and become worn or deformed due to the opening and closing operation of the pair of buckets, the base-side replacement member can be easily replaced with respect to the base-side fixed member, or the bucket-side replacement member can be easily replaced with respect to the bucket-side fixed member. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a left side view showing a shaft excavator equipped with a clamshell bucket according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a perspective view showing a clamshell bucket. [Figure 3] FIG. 10 is a left side view showing the clamshell bucket in a closed position. [Figure 4] 4 is a cross-sectional view of the clamshell bucket as viewed from the direction of arrows IV-IV in FIG. 3. [Figure 5] FIG. 4 is an enlarged view of a main portion showing a base-side contact member and a bucket-side contact member. [Figure 6] FIG. 2 is a perspective view showing a base-side fixed member and a base-side replacement member. [Figure 7] FIG. 10 is a left side view showing the clamshell bucket in the open position. [Figure 8] 8 is a cross-sectional view taken in the direction of arrows VIII-VIII in FIG. 7, showing a state in which the base-side contact member and the bucket-side contact member collide with each other. [Figure 9] 9 is a cross-sectional view similar to FIG. 8, showing a base-side contact member and a bucket-side contact member according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A clamshell bucket according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings, taking as an example a case where it is mounted on a shaft excavator.

[0013] In the figure, a shaft excavating machine 1 comprises a self-propelled crawler-type lower traveling body 2 and an upper rotating body 3 rotatably mounted on the lower traveling body 2. The lower traveling body 2 and upper rotating body 3 form the vehicle body of the shaft excavating machine 1. A working device 4 is provided on the front side of the upper rotating body 3, and this working device 4 can be used to excavate a shaft deep underground.

[0014] The upper rotating body 3 is composed of a rotating frame 5 which serves as the base, a counterweight 6 attached to the rear end of the rotating frame 5, and a cab 7 attached to the left front part of the rotating frame 5. The counterweight 6 maintains the weight balance with the work implement 4 attached to the front side of the upper rotating body 3. The cab 7 defines the driver's compartment where the operator sits, and inside the cab 7 are arranged a driver's seat, operation control levers, operation levers and pedals for traveling (none of which are shown).

[0015] The work device 4 is provided in front of the upper rotating body 3 and excavates a shaft P deep underground. The work device 4 is composed of a boom 8 attached to the front end of the rotating frame 5 so as to be rotatable in the vertical direction, a multi-stage telescopic arm 9 rotatably attached to the tip of the boom 8, and a clamshell bucket 11 (described below) rotatably attached to the tip of the arm 9. The arm 9 has an outer cylinder 9A attached to the tip of the boom 8, a first inner cylinder 9B provided inside the outer cylinder 9A so as to be extendable and retractable, and a second inner cylinder 9C provided inside the first inner cylinder 9B so as to be extendable and retractable, and the clamshell bucket 11 is attached to the tip of the second inner cylinder 9C.

[0016] Next, the clamshell bucket 11 according to this embodiment will be described with reference to FIGS.

[0017] The clamshell bucket 11 is attached to the tip of the arm 9 (second inner cylinder 9C) that constitutes the work device 4. The clamshell bucket 11 is composed of a base member 12, a hydraulic cylinder 13, and a pair of buckets 17, 21, and excavates earth and sand by opening and closing the pair of buckets 17, 21 using the hydraulic cylinder 13, and excavates a shaft P deep underground. For ease of explanation, the direction in which the pair of buckets 17, 21 open and close will be referred to as the opening and closing direction of the clamshell bucket 11, and directions other than the up-and-down direction that are perpendicular to this opening and closing direction will be referred to as the width direction of the clamshell bucket 11.

[0018] The base member 12 is attached to the tip of the arm 9 (second inner cylinder 9C). The base member 12 is a core (foundation) member of the clamshell bucket 11 and is composed of a rod portion 12A extending in the vertical direction and a cross beam portion 12B provided at the lower end of the rod portion 12A. The cross beam portion 12B extends horizontally in the width direction, perpendicular to the axial direction (vertical direction) of the rod portion 12A. As a result, the base member 12 is formed into an inverted T shape as a whole.

[0019] The rod portion 12A of the base member 12 is a cylindrical body extending in the vertical direction, and also serves as the rod of the hydraulic cylinder 13 described below. An arm attachment portion 12C is provided at the upper end of the rod portion 12A, and the arm attachment portion 12C is rotatably attached to the tip of the second inner cylinder 9C that constitutes the arm 9 via a support shaft.

[0020] The cross beam portion 12B of the base member 12 is formed of a rectangular tube extending in the width direction. The center of the cross beam portion 12B in the width direction is fixed to the lower end of the rod portion 12A. Bucket mounting plates 12D that protrude in the opening and closing direction are provided on both ends of the cross beam portion 12B in the width direction, and a pair of buckets 17, 21 are attached to both ends of the bucket mounting plate 12D in the opening and closing direction so as to be rotatable (openable and closable).

[0021] The hydraulic cylinder 13 is configured to include the rod portion 12A of the base member 12. That is, the hydraulic cylinder 13 is formed as a double-rod hydraulic cylinder equipped with the rod portion 12A of the base member 12, a piston (not shown) provided in the axial middle of the rod portion 12A, and a tube 13A provided on the outer periphery of the rod portion 12A and surrounding the piston. The tube 13A is attached to the rod portion 12A so as to be movable in the axial direction (up and down), and an upper oil chamber located above the piston and a lower oil chamber located below the piston are formed within the tube 13A.

[0022] The tube 13A of the hydraulic cylinder 13 moves downward along the rod portion 12A when pressure oil is supplied to the upper oil chamber (see FIG. 3), and moves upward along the rod portion 12A when pressure oil is supplied to the lower oil chamber (see FIG. 7). A pair of link mounting brackets 13B that protrude radially outward from the tube 13A are attached to the axial middle of the tube 13A. One end of a link 14 (described later) is attached to each of the link mounting brackets 13B.

[0023] The pair of links 14 are provided between the tube 13A of the hydraulic cylinder 13 and the buckets 17, 21, respectively. As shown in Fig. 2, the link 14 is formed in a triangular shape with a narrower width on the tube 13A side (upper side) and a wider width on the bucket 17, 21 side (lower side). One end (upper end) 14A of the pair of links 14 is rotatably connected to a link mounting bracket 13B of the hydraulic cylinder 13 using an upper connecting pin 15. The other end (lower end) 14B of the pair of links 14 is rotatably connected to link connecting portions 18D, 22D (described later) of the buckets 17, 21 using a lower connecting pin 16.

[0024] The pair of buckets 17, 21 are rotatably attached to the base member 12 via support pins 20, 24, which will be described later. The buckets 17, 21 are arranged symmetrically in the opening and closing direction across the cross beam portion 12B of the base member 12, and rotate (displace) between an open position (position in FIG. 7) in which they are spaced apart from each other and a closed position (position in FIG. 3) in which they approach each other. The pair of buckets 17, 21 each have openings 17A, 21A located on the bottom side of the shaft P, and scoop up earth and sand through the openings 17A, 21A by displacing from the open position to the closed position. Here, the pair of buckets 17, 21 have the same shape and configuration, so one bucket 17 will be described in detail, and the other bucket 21 will be described briefly.

[0025] Bucket 17 is rotatably supported by a pair of bucket mounting plates 12D provided at both widthwise ends of cross beam portion 12B constituting base member 12, each using a support pin 20. As shown in Figures 3 and 4, bucket 17 is composed of a pair of side plates 18 that face each other with a gap in the widthwise direction and a bottom plate 19 that connects the pair of side plates 18, and the space surrounded by the pair of side plates 18 and bottom plate 19 forms sediment collection space S1 (see Figure 4).

[0026] The side plates 18 of the bucket 17 have a thick, U-shaped thick plate portion 18A that forms the outer frame of the side plate 18, and a thin plate portion 18B that is fixed to the thick plate portion 18A by welding or other means. The thick plate portion 18A reinforces a portion of the side plate 18 where stress concentrates during excavation work using the bucket 17. The thick plate portion 18A is provided with a base member connecting portion 18C that corresponds to the bucket mounting plate 12D of the base member 12, and a link connecting portion 18D that corresponds to the other end 14B of the link 14. The base member connecting portion 18C of the side plate 18 is rotatably connected to the bucket mounting plate 12D of the base member 12 (cross beam portion 12B) using a support pin 20. The link connecting portion 18D of the side plate 18 is rotatably connected to the other end 14B of the link 14 using a lower connecting pin 16.

[0027] The bottom plate 19 of the bucket 17 connects the pair of side plates 18. The bottom plate 19 is formed of a gently curved plate, and both ends of the bottom plate 19 in the width direction are fixed to the pair of side plates 18 by welding or other means. A cutting edge 19A made of a thick plate is fixed across the entire width of the edge of the bottom plate 19 located on the opening 17A side of the bucket 17. A plurality of (e.g., three) excavation claws 19B are attached to the cutting edge 19A at intervals in the width direction.

[0028] Like bucket 17, bucket 21 is composed of a pair of side plates 22 and a bottom plate 23 connecting the pair of side plates 22, and the space surrounded by the pair of side plates 22 and the bottom plate 23 forms a sediment collection space S2 (see Figure 4).

[0029] The side plates 22 of the bucket 21 have a thick plate portion 22A and a thin plate portion 22B, and the thick plate portion 22A is provided with a base member connecting portion 22C and a link connecting portion 22D. The base member connecting portion 22C is rotatably connected to the bucket mounting plate 12D of the base member 12 using a support pin 24, and the link connecting portion 22D is rotatably connected to the other end 14B of the link 14 using a lower connecting pin 16. The bottom plate 23 of the bucket 21 connects the pair of side plates 22, and a cutting edge 23A is fixed to the edge of the bottom plate 23 located on the opening 21A side of the bucket 21. A plurality of excavation claws 23B are attached to the cutting edge 23A at intervals in the width direction.

[0030] Therefore, when tube 13A of hydraulic cylinder 13 moves up and down along rod portion 12A, the movement of tube 13A is transmitted to buckets 17, 21 via link 14. As a result, bucket 17 rotates about support pin 20 and bucket 21 rotates about support pin 24, and clamshell bucket 11 is displaced between the closed position shown in FIG. 3 and the open position shown in FIG. 7.

[0031] A pair of earth removal devices 25, 26 are each provided on the cross beam portion 12B of the base member 12. One earth removal device 25 is disposed in the earth and sand collection space S1 of the bucket 17, and the other earth removal device 26 is disposed in the earth and sand collection space S2 of the bucket 21.

[0032] 4, earth removal device 25 is formed in a frame shape by a pair of mounting members 25A fixed to cross beam portions 12B of base member 12, a pair of L-shaped plates 25B attached to the pair of mounting members 25A and extending toward bottom plate 19 of bucket 17, and scraping plates 25C fixed to the tips of the pair of L-shaped plates 25B and extending in the width direction between the pair of side plates 18 of bucket 17. Scraping plates 25C are fixed in a position close to the inner surface of bottom plate 19. As a result, earth removal device 25 can scrape off soil and sand such as clay and mud stuck to the inner surface of bottom plate 19 by scraping plates 25C when bucket 17 is rotated (moved) from the closed position to the open position.

[0033] Like soil discharge device 25, soil discharge device 26 is formed in a frame shape by a pair of mounting members 26A, a pair of L-shaped plates 26B, and scraping plate 26C, and scraping plate 26C is fixed to a position close to the inner surface of bottom plate 23 that constitutes bucket 21. This allows soil discharge device 26 to scrape off soil and sand such as clay and mud stuck to the inner surface of bottom plate 23 by scraping plate 26C when bucket 21 is rotated from the closed position to the open position.

[0034] Next, the base side contact member 27 and the bucket side contact members 32 and 36 used in this embodiment will be described.

[0035] One base-side abutment member 27 is provided at each end in the width direction of cross beam portion 12B that constitutes base member 12 (two in total) (see FIG. 4). When hydraulic cylinder 13 displaces clamshell bucket 11 from the closed position to the open position, bucket-side abutment members 32, 36 provided on buckets 17, 21 abut against base-side abutment member 27. This sets the open position (maximum opening) of clamshell bucket 11 and prevents tube 13A of hydraulic cylinder 13 from moving beyond an appropriate range.

[0036] As shown in Figures 6 and 8, the base-side abutment member 27 is composed of a base-side fixed member 28 fixed to the cross beam portion 12B of the base member 12, and base-side replacement members 29, 30 attached to the base-side fixed member 28 in a replaceable (detachable) manner using bolts 31.

[0037] The base-side fixing member 28 has a rectangular parallelepiped block shape and is fixed to the upper surface of the cross beam portion 12B by means of welding or the like. One side surface 28A of the base-side fixing member 28 that faces the bucket 17 and the other side surface 28B that faces the bucket 21 each have a plurality (for example, four) of bolt holes (internal thread holes) 28C formed therein. Furthermore, each of the one side surface 28A and the other side surface 28B of the base-side fixing member 28 has a notched groove 28D formed therein as a concave fitting portion. The notched groove 28D is formed by cutting out a linear notch in the vertical direction at the center of the width of the one side surface 28A and the other side surface 28B of the base-side fixing member 28 across the entire area from the top surface to the bottom surface of the base-side fixing member 28.

[0038] The base-side replacement member 29 is replaceably attached to one side 28A of the base-side fixing member 28 using four bolts 31, and the base-side replacement member 30 is replaceably attached to the other side 28B of the base-side fixing member 28 using four bolts 31.

[0039] The base-side replacement member 29 is formed from a thick, rectangular plate that is the same size as one side surface 28A of the base-side fixing member 28. Four bolt insertion holes 29A are formed in the base-side replacement member 29, corresponding to the bolt holes 28C formed in one side surface 28A of the base-side fixing member 28. Counterbore holes 29B for accommodating the heads of bolts 31 are formed concentrically in these four bolt insertion holes 29A. In addition, a fitting protrusion 29C serving as a convex fitting portion is provided on the surface of the base-side replacement member 29 that abuts against the one side surface 28A of the base-side fixing member 28. The fitting protrusion 29C is formed as a linear protrusion that extends vertically through the center of the width direction of the base-side replacement member 29, and fits into the notched groove 28D of the base-side fixing member 28.

[0040] Then, by fitting the fitting protrusion 29C of the base-side replacement member 29 into the notch groove 28D of the base-side fixing member 28, the bolt hole 28C of the base-side fixing member 28 and the bolt insertion hole 29A of the base-side replacement member 29 can be aligned. In this state, a bolt 31 is inserted through the bolt insertion hole 29A of the base-side replacement member 29, and this bolt 31 is screwed into the bolt hole 28C of the base-side fixing member 28, whereby the base-side replacement member 29 can be attached to one side surface 28A of the base-side fixing member 28.

[0041] In this case, as shown in Fig. 4, the gap A formed between the notch groove 28D and the fitting protrusion 29C is set smaller than the radial gap B formed between the bolt insertion hole 29A of the base-side replacement member 29 and the bolt 31 (A < B). Thereby, even when a large load acts on the base-side replacement member 29 due to the collision of the bucket-side replacement member 34 described later, this load can be received by the fitting portion between the notch groove 28D and the fitting protrusion 29C prior to the bolt 31, and damage to the bolt 31 can be prevented.

[0042] On the other hand, the base-side replacement member 30 has the same shape and structure as the base-side replacement member 29. That is, the base-side replacement member 30 is formed with four bolt insertion holes 30A corresponding to the bolt holes 28C provided on the other side surface 28B of the base-side fixing member 28, and counterboring holes 30B. Further, the base-side replacement member 30 is formed with a fitting protrusion 30C as a convex fitting portion that fits into the notch groove 28D provided on the other side surface 28B of the base-side fixing member 28.

[0043] The gap formed between the notch groove 28D and the fitting protrusion 30C is set smaller than the gap formed between the bolt insertion hole 30A of the base-side replacement member 30 and the bolt 31. Then, in a state where the fitting protrusion 30C of the base-side replacement member 30 is fitted into the notch groove 28D of the base-side fixing member 28, the bolt 31 inserted through the bolt insertion hole 30A of the base-side replacement member 30 is screwed into the bolt hole 28C of the base-side fixing member 28. Thereby, the base-side replacement member 30 can be attached to the other side surface 28B of the base-side fixing member 28.

[0044] One bucket-side abutment member 32 is provided on each of the pair of side plates 18 that make up the bucket 17 (two in total). The bucket-side abutment member 32 collides with the base-side abutment member 27 when the bucket 17 moves to the open position, thereby setting the open position (maximum opening degree) of the bucket 17. The bucket-side abutment member 32 is made up of a bucket-side fixed member 33 that is fixed to the pair of side plates 18 that make up the bucket 17, and a bucket-side replaceable member 34 that is replaceably (detachably) attached to the bucket-side fixed member 33 with bolts 35.

[0045] The bucket-side fixing member 33 is formed from a thick, rectangular plate, and is fixed by means of welding or the like to a position of the thick plate portion 18A of the side plate 18 in proximity to the base member connecting portion 18C. One side surface 33A of the bucket-side fixing member 33 facing the base-side abutment member 27 is formed with a plurality of (for example, four) bolt holes (internal thread holes) 33B, and is also formed with a notched groove 33C as a concave fitting portion. The notched groove 33C is formed by cutting out a linear notch in the vertical direction at the center of the width direction of the bucket-side fixing member 33 over the entire area from the top surface to the bottom surface of the bucket-side fixing member 33.

[0046] The bucket-side replacement member 34 is formed from a rectangular plate having the same shape as the bucket-side fixing member 33. Four bolt insertion holes 34A corresponding to the bolt holes 33B formed in one side surface 33A of the bucket-side fixing member 33, and countersunk holes 34B for accommodating the heads of the bolts 35 are formed concentrically in the bucket-side replacement member 34. In addition, a fitting protrusion 34C serving as a convex fitting portion is provided on the surface of the bucket-side replacement member 34 that abuts against the one side surface 33A of the bucket-side fixing member 33. The fitting protrusion 34C is formed as a linear protrusion extending vertically through the center of the width direction of the bucket-side replacement member 34, and fits into the notched groove 33C of the bucket-side fixing member 33.

[0047] In this case, the gap formed between the notched groove 33C and the fitting protrusion 34C is set smaller than the gap formed between the bolt 35 and the bolt insertion hole 34A of the bucket-side replacement member 34. Then, with the fitting protrusion 34C of the bucket-side replacement member 34 fitted into the notched groove 33C of the bucket-side fixing member 33, the bolt 35 inserted into the bolt insertion hole 34A of the bucket-side replacement member 34 is screwed into the bolt hole 33B of the bucket-side fixing member 33. This makes it possible to attach the bucket-side replacement member 34 to one side surface 33A of the bucket-side fixing member 33 in a replaceable manner.

[0048] One bucket-side abutment member 36 is provided on each of the pair of side plates 22 that constitute the bucket 21 (two in total). The bucket-side abutment member 36 collides with the base-side abutment member 27 when the bucket 21 moves to the open position, thereby setting the open position (maximum opening degree) of the bucket 21. The bucket-side abutment member 36 is made up of a bucket-side fixed member 37 that is fixed to the pair of side plates 22 that constitute the bucket 21, and a bucket-side replaceable member 38 that is replaceably attached to the bucket-side fixed member 37 using bolts 35.

[0049] Bucket-side fixing member 37 is formed from a thick, rectangular plate, and is fixed by means of welding or the like to a position close to base member connecting portion 22C of thick plate portion 22A of side plate 22. One side surface 37A of bucket-side fixing member 37 facing base-side abutment member 27 has multiple bolt holes 37B formed therein, and also has a notched groove 37C as a concave fitting portion.

[0050] Bucket-side replacement member 38 is formed from a rectangular plate having the same shape as bucket-side fixing member 37. Bucket-side replacement member 38 is formed with four concentric bolt insertion holes 38A corresponding to bolt holes 37B formed in one side surface 37A of bucket-side fixing member 37, and countersunk holes 38B for accommodating the heads of bolts 35. In addition, a surface of bucket-side replacement member 38 that abuts against one side surface 37A of bucket-side fixing member 37 is provided with fitting protrusions 38C as convex fitting portions, and fitting protrusions 38C fit into notched grooves 37C of bucket-side fixing member 37.

[0051] In this case, the gap formed between the notched groove 37C and the fitting protrusion 38C is set smaller than the gap formed between the bolt 35 and the bolt insertion hole 38A of the bucket-side replacement member 38. Then, with the fitting protrusion 38C of the bucket-side replacement member 38 fitted into the notched groove 37C of the bucket-side fixing member 37, the bolt 35 inserted into the bolt insertion hole 38A of the bucket-side replacement member 38 is screwed into the bolt hole 37B of the bucket-side fixing member 37. This makes it possible to attach the bucket-side replacement member 38 to one side surface 37A of the bucket-side fixing member 37 in a replaceable manner.

[0052] When the clamshell bucket 11 is used to excavate a shaft P, the buckets 17, 21 open and close, causing the bucket-side replacement member 34 of the bucket-side abutment member 32 to collide with the base-side replacement member 29 of the base-side abutment member 27, and the bucket-side replacement member 38 of the bucket-side abutment member 36 to collide with the base-side replacement member 30 of the base-side abutment member 27. In this way, the bucket-side replacement members 34, 38 and the base-side replacement members 29, 30 gradually wear out and become deformed due to the impacts of repeated collisions.

[0053] In contrast to this, in this embodiment, base-side replacement members 29 and 30 can be easily replaced with respect to base-side fixed member 28 fixed to base member 12 using bolts 31. Furthermore, bucket-side replacement member 34 can be easily replaced with respect to bucket-side fixed member 33 fixed to bucket 17 using bolts 35, and bucket-side replacement member 38 can be easily replaced with respect to bucket-side fixed member 37 fixed to bucket 21 using bolts 35.

[0054] If the bucket-side replacement parts 34, 38 and the base-side replacement parts 29, 30 were made of the same material, they would each suffer from equal wear and deformation, which would require frequent replacement of the bucket-side replacement parts 34, 38 and the base-side replacement parts 29, 30.

[0055] In contrast, in this embodiment, base-side replacement parts 29 and 30 that constitute base-side contact member 27, bucket-side replacement part 34 that constitutes bucket-side contact member 32, and bucket-side replacement part 38 that constitutes bucket-side contact member 36 are formed using materials with different hardnesses. Specifically, base-side replacement parts 29 and 30 are formed using, for example, general structural rolled steel, while bucket-side replacement parts 34 and 38 are formed using wear-resistant steel that is harder and has excellent wear resistance than general structural rolled steel.

[0056] As a result, because wear occurs primarily in the base-side replacement parts 29 and 30 that constitute the base-side abutment member 27, the effort required to replace the bucket-side replacement part 34 of the bucket-side abutment member 32 and the bucket-side replacement part 38 of the bucket-side abutment member 36 can be eliminated, improving the workability of the replacement work. The reason for increasing the hardness of the material of the bucket-side replacement parts 34 and 38 is as follows. Specifically, the bucket-side fixing member 33 to which the bucket-side replacement part 34 is attached and the bucket-side fixing member 37 to which the bucket-side replacement part 38 is attached are both formed of rectangular plates, and the welded parts to the side plate 18 of the bucket 17 and the side plate 22 of the bucket 21 are small, making them more susceptible to deformation than the block-shaped base-side fixing member 28. For this reason, it is desirable to form the bucket-side replacement parts 34 and 38 using a wear-resistant steel material so that they do not deform due to the impact when they collide with the base-side replacement parts 29 and 30.

[0057] The clamshell bucket 11 according to this embodiment has the configuration as described above, and the excavation work of the shaft P using the clamshell bucket 11 will be described below.

[0058] First, as shown in Figure 1, shaft excavator 1 is driven to the vicinity of shaft P, and then boom 8 of work device 4 is extended forward, and multi-stage telescopic arm 9 is extended vertically relative to the ground. Then, with buckets 17 and 21 of clamshell bucket 11 held in the open position, first inner cylinder 9B and second inner cylinder 9C are extended from outer cylinder 9A of arm 9, thereby bringing clamshell bucket 11 into contact with the bottom (hole bottom) of shaft P. In this state, buckets 17 and 21 are rotated from the open position to the closed position, allowing soil and sand at the bottom of shaft P to be scooped up.

[0059] After the earth and sand has been scooped up by the clamshell bucket 11, the first inner cylinder 9B and the second inner cylinder 9C are housed inside the outer cylinder 9A of the arm 9, and the arm 9 is retracted. In this state, the tip of the boom 8 is lifted upward, and the arm 9 is rotated at the tip side of the boom 8, thereby allowing the clamshell bucket 11 to be withdrawn upward from the shaft P. After the clamshell bucket 11 has been withdrawn upward from the shaft P, the upper rotating body 3 is rotated to move the clamshell bucket 11 above a dump truck (not shown). Then, the buckets 17, 21 are rotated from the closed position to the open position, thereby discharging the excavated earth and sand into the bed of the dump truck.

[0060] In this way, after the earth and sand have been discharged, the upper rotating body 3 is rotated to position the clamshell bucket 11 above the shaft P, and by repeating the above-mentioned process, the shaft P can be excavated deep underground.

[0061] Here, during the excavation work of the shaft P, the buckets 17, 21 constituting the clamshell bucket 11 repeatedly open and close. When the buckets 17, 21 rotate from the closed position to the open position, the bucket-side abutment members 32, 36 provided on the bucket 17 collide with the base-side abutment member 27 provided on the base member 12. This sets the open position (maximum opening) of the buckets 17, 21, and prevents the tube 13A of the hydraulic cylinder 13 from moving beyond an appropriate range, thereby preventing an excessive load from acting on the hydraulic cylinder 13.

[0062] In this case, as the buckets 17, 21 repeatedly open and close, the bucket-side replacement member 34 of the bucket-side abutment member 32 repeatedly collides with the base-side replacement member 29 of the base-side abutment member 27, and the bucket-side replacement member 38 of the bucket-side abutment member 36 repeatedly collides with the base-side replacement member 30 of the base-side abutment member 27. For this reason, the bucket-side replacement members 34, 38 and the base-side replacement members 29, 30 gradually wear and deform due to the impact of the collision.

[0063] In contrast, in the present embodiment, base-side replacement members 29 and 30 can be easily replaced with respect to base-side fixed member 28 fixed to base member 12 using bolts 31. Furthermore, bucket-side replacement member 34 can be easily replaced with respect to bucket-side fixed member 33 fixed to bucket 17 using bolts 35, and bucket-side replacement member 38 can be easily replaced with respect to bucket-side fixed member 37 fixed to bucket 21 using bolts 35. This improves the ease of replacement of base-side replacement members 29 and 30 and bucket-side replacement members 34 and 38 that have become worn, deformed, or the like.

[0064] Moreover, in this embodiment, base-side replacement members 29, 30 are formed using, for example, general structural rolled steel, and bucket-side replacement members 34, 38 are formed using a wear-resistant steel material that is harder and more wear-resistant than general structural rolled steel. As a result, since it is mainly base-side replacement members 29, 30 that constitute base-side abutment member 27 that wear out, it is possible to eliminate the effort required to replace bucket-side replacement member 34 of bucket-side abutment member 32 and bucket-side replacement member 38 of bucket-side abutment member 36, and the workability of the replacement work can be further improved.

[0065] Furthermore, in this embodiment, when the base-side replacement members 29, 30 constituting the base-side abutment member 27 are attached to the base-side fixing member 28 using the bolts 31, the fitting protrusions 29C, 30C provided on the base-side replacement members 29, 30 can be fitted into the notched grooves 28D provided in the base-side fixing member 28. As a result, even if a large load acts on the base-side replacement member 29 due to a collision of the bucket-side replacement member 34, the load can be borne by the fitting portion between the notched grooves 28D and the fitting protrusions 29C before being borne by the bolts 31. Similarly, even if a large load acts on the base-side replacement member 30 due to a collision of the bucket-side replacement member 38, the load can be borne by the fitting portion between the notched grooves 28D and the fitting protrusions 30C before being borne by the bolts 31. As a result, breakage of the bolts 31 can be prevented, and the base-side replacement members 29, 30 can be reliably attached to the base-side fixing member 28 for a long period of time.

[0066] On the other hand, when bucket-side replacement part 34 constituting bucket-side abutment member 32 is attached to bucket-side fixing member 33 using bolts 35, fitting protrusion 34C provided on bucket-side replacement part 34 can be fitted into notched groove 33C provided in bucket-side fixing member 33. Also, when bucket-side replacement part 38 constituting bucket-side abutment member 36 is attached to bucket-side fixing member 37 using bolts 35, fitting protrusion 38C provided on bucket-side replacement part 38 can be fitted into notched groove 37C provided in bucket-side fixing member 37. As a result, even if a large load acts on bucket-side replacement parts 34, 38 due to a collision between base-side replacement parts 29, 30, this load can be supported by the fitting portion between notched groove 33C and fitting protrusion 34C and the fitting portion between notched groove 37C and fitting protrusion 38C. As a result, it is possible to prevent the bolts 35 from breaking, and the bucket-side replacement members 34, 38 can be securely attached to the bucket-side fixing members 33, 37 for a long period of time.

[0067] Thus, the clamshell bucket 11 according to the embodiment includes a base member 12 attached to the tip side of the arm 9 constituting the working device 4, a pair of buckets 17, 21 rotatably supported on the base member 12 via support pins 20, 24 and displaceable between an open position in which they are separated from each other and a closed position in which they approach each other, a base-side abutment member 27 provided on the base member 12, and bucket-side abutment members 32, 36 provided on each of the pair of buckets 17, 21 and which abut against the base-side abutment member 27 when the buckets 17, 21 are displaced to the open position.

[0068] The base-side abutment member 27 is composed of a base-side fixed member 28 fixed to the base member 12 and base-side replaceable members 29, 30 replaceably attached to the base-side fixed member 28, and the bucket-side abutment members 32, 36 are composed of bucket-side fixed members 33, 37 fixed to the buckets 17, 21 and bucket-side replaceable members 34, 38 replaceably attached to the bucket-side fixed members 33, 37 and abutting against the base-side replaceable members 29, 30.

[0069] According to this configuration, even if the base-side replaceable members 29, 30 and the bucket-side replaceable members 34, 38 repeatedly collide with each other and become worn or deformed due to the opening and closing operations of the buckets 17, 21, the base-side replaceable members 29, 30 can be easily replaced with respect to the base-side fixed member 28, or the bucket-side replaceable members 34, 38 can be easily replaced with respect to the bucket-side fixed members 33, 37. This improves the ease of repair work when repairing the base-side abutment member 27 and the bucket-side abutment members 32, 36 that have worn or deformed.

[0070] In the embodiment, the base-side replacement parts 29, 30 and the bucket-side replacement parts 34, 38 are formed using materials with different hardnesses. With this configuration, repeated collisions between the base-side replacement parts 29, 30 and the bucket-side replacement parts 34, 38 cause the base-side replacement parts 29, 30 and the bucket-side replacement parts 34, 38, whichever is formed using a material with a lower hardness, to wear and deform preferentially. As a result, the effort required to replace the parts formed using a material with a higher hardness can be eliminated, and the workability when replacing the base-side replacement parts 29, 30 and the bucket-side replacement parts 34, 38 can be improved.

[0071] In the embodiment, base-side fixing member 28 is provided with cutout groove 28D, and base-side replacement members 29, 30 are provided with fitting protrusions 29C, 30C that fit into notch groove 28D when base-side replacement members 29, 30 are attached to base-side fixing member 28. Bucket-side fixing members 33, 37 are provided with cutout grooves 33C, 37C, and bucket-side replacement members 34, 38 are provided with fitting protrusions 34C, 38C that fit into notch grooves 33C, 37C when bucket-side replacement members 34, 38 are attached to bucket-side fixing members 33, 37.

[0072] According to this configuration, even if a large load acts on the base-side replacement parts 29, 30 due to a collision of the bucket-side replacement parts 34, 38, the load can be received by the fitting portions between the notched grooves 28D, 28D and the fitting protrusions 29C, 30C, preventing the base-side replacement parts 29, 30 from coming off due to breakage of the bolts 31, etc. Similarly, even if a large load acts on the bucket-side replacement parts 34, 38 due to a collision of the base-side replacement parts 29, 30, the load can be received by the fitting portions between the notched grooves 33C and the fitting protrusions 34C and the fitting portions between the notched grooves 37C and the fitting protrusions 38C, preventing the bucket-side replacement parts 34, 38 from coming off due to breakage of the bolts 35, etc.

[0073] In the above-described embodiment, the base-side fixing member 28 constituting the base-side abutment member 27 has the cutout groove 28D formed therein, and the base-side replacement members 29, 30 have the fitting protrusions 29C, 30C formed therein. Furthermore, the bucket-side fixing members 33, 37 constituting the bucket-side abutment members 32, 36 have the cutout grooves 33C, 37C formed therein, and the bucket-side replacement members 34, 38 have the fitting protrusions 34C, 38C formed therein. However, the present invention is not limited to this. For example, as shown in a modified example in FIG. 9 , the base-side abutment member 27' may be formed by a base-side fixing member 28' without a cutout groove and base-side replacement members 29', 30' without an engaging protrusion, and the bucket-side abutment members 32', 36' may be formed by bucket-side fixing members 33', 37' without a cutout groove and bucket-side replacement members 34', 38' without an engaging protrusion.

[0074] In addition, in the embodiment, a case is illustrated in which the notched groove 28D is formed in the base-side fixed member 28 constituting the base-side abutment member 27, and the fitting protrusions 29C, 30C are formed in the base-side replacement members 29, 30. However, the present invention is not limited to this. For example, the fitting protrusion may be formed in the base-side fixed member, and the notched groove may be formed in the base-side replacement member. The same applies to the bucket-side abutment member.

[0075] In addition, in the embodiment, the concave-convex fitting portions provided on the base-side fixed member 28 and the base-side replaceable members 29, 30 are exemplified by the linear notched groove 28D formed in the base-side fixed member 28 and the linear fitting protrusions 29C, 30C formed in the base-side replaceable members 29, 30. However, the present invention is not limited to this. For example, a circular hole may be formed in one of the base-side fixed member and the base-side replaceable member, and a cylindrical protrusion that fits into the circular hole may be formed in the other member. The same applies to the bucket-side abutment member.

[0076] Furthermore, in the embodiment, the hardness of the material forming the bucket-side replacement parts 34, 38 is set to be higher than the hardness of the material forming the base-side replacement parts 29, 30. However, the present invention is not limited to this, and for example, the hardness of the material forming the bucket-side replacement parts 34, 38 may be lower than the hardness of the material forming the base-side replacement parts 29, 30. [Explanation of symbols]

[0077] 4 Work equipment 11 Clamshell Bucket 12 Base member 17,21 Bucket 20,24 Support pin 27, 27′ Base side abutment member 28, 28′ Base side fixing member 29, 30, 29', 30' Base side replacement parts 32, 36, 32', 36' Bucket side contact member 33, 37, 33', 37' Bucket side fixing member 34, 38, 34', 38' Bucket side replacement parts 28D, 33C, 37C Notched groove (recessed fitting part) 29C, 30C, 34C, 38C Fitting protrusion (convex fitting part)

Claims

1. a base member attached to the tip side of the arm constituting the working device; a pair of buckets rotatably supported on the base member via support pins and displaceable between an open position in which they are spaced apart and a closed position in which they approach each other; a base-side contact member provided on the base member; a bucket-side abutment member that is provided on each of the pair of buckets and abuts against the base-side abutment member when the pair of buckets are displaced to the open position, the base-side contact member is composed of a base-side fixed member fixed to the base member and a base-side replaceable member replaceably attached to the base-side fixed member, the bucket side abutment members are composed of bucket side fixed members fixed to the pair of buckets, and bucket side replacement members replaceably attached to the bucket side fixed members and abutting against the base side replacement members, 10. A clamshell bucket, wherein the base-side replacement member and the bucket-side replacement member are formed using materials with different hardnesses.

2. A base member attached to the tip side of an arm constituting a working device; a pair of buckets rotatably supported on the base member via support pins and displaceable between an open position in which they are spaced apart and a closed position in which they approach each other; a base-side contact member provided on the base member; a bucket-side abutment member that is provided on each of the pair of buckets and abuts against the base-side abutment member when the pair of buckets are displaced to the open position, the base-side contact member is composed of a base-side fixed member fixed to the base member and a base-side replaceable member replaceably attached to the base-side fixed member, the bucket side abutment members are composed of bucket side fixed members fixed to the pair of buckets, and bucket side replacement members replaceably attached to the bucket side fixed members and abutting against the base side replacement members, the base-side fixing member and the base-side replacement member are provided with a concave-convex fitting portion that fits with each other in a state in which the base-side replacement member is attached to the base-side fixing member, a bucket-side replacement member that is provided with a recessed and projecting fitting portion that fits with the bucket-side replacement member when the bucket-side replacement member is attached to the bucket-side replacement member;

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