Clamshell Bucket

Abstract

To reduce the difference in height between when a pair of shells of a rope-type clamshell bucket are opened and when the pair of shells are closed.SOLUTION: A clamshell bucket includes a pair of shells rotated between a closed position and an opened position, a movable body rotationally connected to the pair of shells with a connection pin above an opening part of the pair of shells arranged in the closed position and moved vertically to open / close the pair of shells, a support body rotationally supporting the shells with support pins between the closed position and the opened position at each of a space on one side and a space on the other side while sandwiching a vertical surface passing the center of the connection pin, and sheaves each provided on the movable body and the support body around which a rope for vertically moving the movable body is wound. The support pins are provided at positions closer to the vertical surface side than outer end parts of the pair of shells in the orthogonal direction orthogonal to the vertical surface at each of the space on the one side and the space on the other side while the pair of shells are arranged at the closed position.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rope-type clamshell bucket that opens and closes a pair of shells using a rope. [Background technology]

[0002] In recent years, the demand for rebuilding high-rise buildings has been increasing in urban areas in Japan, and there is a growing need for deep foundation excavators that are compatible with the inverted construction method, which performs construction above and below ground simultaneously, in order to shorten the construction period and ensure stable underground construction on soft ground. At inverted construction sites, the excavation work is performed indoors, so the working height is limited and the clamshell bucket of the deep foundation excavator cannot be lifted high. The clamshell bucket unloads soil during civil engineering work using a pair of shells that can be opened and closed, and the pair of shells are opened above the bed of a dump truck to load the soil into the bed of the dump truck.

[0003] The main deep foundation excavator is a mechanical clamshell based on a crawler crane. In the mechanical clamshell, a rope-type clamshell bucket that is operated by a rope is used. In the rope-type clamshell bucket, as the pair of shells open, the position of the pair of shells changes downward, and the height of the clamshell bucket increases. In this way, the difference in height of the clamshell bucket when the pair of shells are open and closed becomes large, so that the clamshell bucket must be handled with care at construction sites where the working height is limited. In addition, when soil and sand are loaded onto the bed of a dump truck, there is a concern that the pair of shells may come into contact with the bottom of the bed and damage the bottom of the bed.

[0004] In contrast, in the clamshell bucket described in Patent Document 1, the bucket link connecting the suspension frame and the clamshell is formed in a bent shape in order to reduce the height dimension of the entire structure. The intermediate position of the bent upper half of the bucket link is connected to the suspension frame, and the end of the bent lower half of the bucket link is connected to one of the clamshells. In addition, the tip of the bent upper half of the bucket link is connected to a connecting link that is connected to the other clamshell. This link structure reduces the overall height dimension of the clamshell bucket when the pair of clamshells are closed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-184123 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the clamshell bucket described in Patent Document 1, when the pair of clamshells are opened, the position of the pair of clamshells changes significantly downward, making it difficult to reduce the difference in height of the clamshell bucket when the pair of clamshells are opened and closed.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a rope-type clamshell bucket that reduces the difference in height between when a pair of shells are opened and when they are closed. [Means for solving the problem]

[0008] In order to achieve the above object, a representative embodiment of the present invention is a clamshell bucket including a pair of openable and closable shells that rotate between a closed position in which their openings face each other and an open position in which the openings are spaced apart, a movable body that rotatably connects the pair of shells by a connecting pin above the openings of the pair of shells arranged in the closed position and moves in a vertical direction to open and close the pair of shells, supports that rotatably support the shells between the closed position and the open position by a support pin in each of a space on one side and a space on the other side of a vertical plane passing through the center of the connecting pin, and sheaves that are provided on each of the movable body and the support and around which a rope that moves the movable body in a vertical direction is hung, The shell has a bottom surface portion and a pair of side surfaces protruding from the bottom surface portion and facing each other, the side surfaces having an upper edge plate located at an upper edge portion and extending from an outer end portion of the shell toward the vertical surface, an opening edge plate located at an edge portion of the opening, and a side plate located between the upper edge plate and the opening edge plate, the upper edge plate being a thick plate portion thicker than the side plates, When the pair of shells are disposed at the closed position, the support pin is provided in each of the one-side space and the other-side space, and the pair of shells are supported in a direction perpendicular to the vertical plane. The upper edge plate of The above It is provided at a position closer to the vertical surface than the outer end. The support body has a support frame and a link connected to the support frame by a link pin and connected to the shell by the support pin, and the support pin is provided at a position on the upper edge plate closer to the vertical plane than the outer end in the orthogonal direction and closer to the outer end than the link pin. It is characterized by the fact that Effect of the Invention

[0009] According to the present invention, it is possible to reduce the difference in height of the clamshell bucket when the pair of shells are opened and when they are closed. Note that problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0010] [Figure 1] 1 is a side view of an excavator, which is a representative example of a work machine provided with a clamshell bucket according to the present invention. [Diagram 2] 2 is an enlarged front view of the clamshell bucket shown in FIG. 1. [Diagram 3] FIG. 2 is a front view showing the clamshell bucket in an open position. [Figure 4] FIG. 1 is a front view showing an example of a conventional clamshell bucket. [Diagram 5]FIG. 2 is a front view showing changes in height when the clamshell bucket of the present embodiment and a conventional clamshell bucket are opened and closed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment of a clamshell bucket according to the present invention will be described with reference to the drawings. Fig. 1 is a side view of an excavator 1, which is a representative example of a work machine provided with a clamshell bucket according to the present invention.

[0012] The excavator 1 is a mechanical clamshell based on a crawler crane. The excavator 1 comprises a lower traveling body 2, an upper rotating body 3 rotatably mounted on the lower traveling body 2, a boom 4 attached to the upper rotating body 3, and a rope-type clamshell bucket 5. The lower traveling body 2 and the upper rotating body 3 are an example of the main body of the excavator 1. The lower traveling body 2 comprises a pair of left and right endless tracks 6. When the rotation of a traveling motor (not shown) is transmitted to the pair of left and right endless tracks 6 and the endless tracks 6 rotate, the excavator 1 travels.

[0013] The upper rotating body 3 is supported by the lower traveling body 2 and rotates by a rotating motor (not shown). The upper rotating body 3 comprises a rotating frame 7 which serves as a base, a cab 8 arranged in front of the rotating frame 7, and a counterweight 9 arranged in the rear of the rotating frame 7. The boom 4 is attached to the front of the rotating frame 7 so as to be rotatable in the vertical direction. The counterweight 9 is a heavy weight for balancing the weight of the boom 4, and is supported by the rotating frame 7.

[0014] The cab 8 has an internal space in which an operator who operates the excavator 1 sits. Inside the cab 8, a seat (not shown) on which the operator sits and operation devices (steering wheel, pedals, levers, switches, etc.) operated by the operator seated on the seat are arranged. The operator in the cab 8 uses the operation devices to control the travel of the lower traveling body 2, the rotation of the upper rotating body 3, the vertical rotation of the boom 4, and the operation of the clamshell bucket 5.

[0015] The clamshell bucket 5 is attached with a lifting rope 10 and an opening / closing rope 11, which are wire ropes. The clamshell bucket 5 operates by means of two ropes, the lifting rope 10 and the opening / closing rope 11. The upper rotating body 3 is equipped with two drums, an auxiliary drum (not shown) around which the lifting rope 10 is wound, and a main hoist drum (not shown) around which the opening / closing rope 11 is wound. The lifting rope 10 and the opening / closing rope 11 are respectively hung over the tip of the boom 4 between the drums and the clamshell bucket 5. When the clamshell bucket 5 operates, the lifting rope 10 and the opening / closing rope 11 are respectively paid out from the drums and wound up on the drums. The clamshell bucket 5 excavates soil and loads it onto the loading platform 13 of the dump truck 12.

[0016] An anti-sway rope 14 is attached to the clamshell bucket 5. The anti-sway rope 14 is hung on the boom 4 between the upper rotating body 3 and the clamshell bucket 5. The anti-sway rope 14 prevents the clamshell bucket 5 suspended by the lifting rope 10 and the opening / closing rope 11 from rotating. Fig. 2 is an enlarged front view of the clamshell bucket 5 shown in Fig. 1. Fig. 3 is a front view showing the clamshell bucket 5 in an open state.

[0017] The clamshell bucket 5 includes a pair of shells 15, 16 that can be opened and closed between a closed position P1 and an open position P2, a support 20 that supports the pair of shells 15, 16 so that they can be opened and closed, a moving body 30 that moves in the vertical direction relative to the support 20, and a plurality of sheaves 40, 41 provided on the support 20 and the moving body 30, respectively. The pair of shells 15, 16 are connected to each other so that they can be opened and closed, and open and close in accordance with the vertical movement of the moving body 30 while being supported by the support 20. The support 20 is suspended by a lifting rope 10. The moving body 30 is suspended by an opening and closing rope 11 via the sheaves 40, 41.

[0018] The support body 20 has a support frame 21, which is an upper frame of the clamshell bucket 5, and a rotatable link 22. The lifting rope 10 is fixed to the support frame 21 by a socket 23 and a fixing member 24 arranged on the upper side of the support frame 21. The socket 23 is attached to the lifting rope 10, and the fixing member 24 is attached to the socket 23 and the support frame 21 by a pin (not shown). The support frame 21 is suspended by the lifting rope 10 via the socket 23 and the fixing member 24. The lifting rope 10 may be fixed directly to the support frame 21.

[0019] The support body 20 supports each of the pair of shells 15, 16 rotatably between a closed position P1 and an open position P2 by support pins 25, 26. The pair of shells 15, 16 are connected to the support body 20 by support pins 25, 26 attached to the support body 20 so as to be rotatable and openable / closable. Of the pair of shells 15, 16, one shell 15 is supported by one support pin 25 attached to the support frame 21, and the other shell 16 is supported by the other support pin 26 attached to the link 22.

[0020] The support frame 21 has a support rod 27 that extends diagonally downward to one of the shells 15. The upper end of the link 22 is attached to a link pin 28 attached to the support frame 21. The link 22 extends diagonally downward from the support frame 21 to the other shell 16. One support pin 25 is attached to the lower end of the support rod 27, and the other support pin 26 is attached to the lower end of the link 22. The link 22 is rotatably connected to the support frame 21 by the link pin 28 and to the shell 16 by the support pin 26.

[0021] Of the upper and lower sheaves 40, 41 spaced apart in the vertical direction, the upper multiple sheaves 40 are attached to the support frame 21 of the support body 20, and the lower multiple sheaves 41 are attached to the moving body 30. The opening / closing rope 11 is looped back around the sheave 41 provided on the moving body 30 and the sheave 40 provided on the support body 20, and is hung in turn around the lower sheave 41 and the upper sheave 40. The opening / closing rope 11 is hung around the multiple sheaves 40, 41 and fixed to the fixed part 29 of the support frame 21. Below the sheave 40, the sheave 41 and the moving body 30 move upward as the opening / closing rope 11 is wound up, and move downward as the opening / closing rope 11 is let out.

[0022] The opening / closing ropes 11 move the moving body 30, which is the lower frame of the clamshell bucket 5, in the vertical direction relative to the support body 20. A rope guide 42 is provided on the support frame 21. The opening / closing ropes 11 pass through and are guided by the rope guide 42. When the clamshell bucket 5 tilts, the rope guide 42 prevents the opening / closing ropes 11 from contacting the groove edges of the sheaves 40, 41 and receiving irregular external forces. This extends the life of the opening / closing ropes 11. The rope guide 42 may be a guide having a structure in which the opening / closing ropes 11 are sandwiched between multiple rollers.

[0023] The openings 50 of the pair of shells 15, 16 are inlets and outlets through which soil and sand flow in and out, and are open downward when the pair of shells 15, 16 are arranged in the open position P2. The pair of shells 15, 16 rotate to open and close between a closed position P1 where the openings 50 face each other and are closed, and an open position P2 where the openings 50 are separated from each other and are open. Above the openings 50 of the pair of shells 15, 16 arranged in the closed position P1, the pair of shells 15, 16 are rotatably connected to the movable body 30 by a connecting pin 31, and are also rotatably connected to each other.

[0024] Each of the pair of shells 15, 16 has a bottom surface portion 60 and a pair of side surfaces 70 that protrude from the bottom surface portion 60 and face each other at a distance. When the pair of shells 15, 16 are arranged in the closed position P1, the bottom surface portion 60 is located at the bottom of the shells 15, 16, and the pair of side surfaces 70 protrude upward from the bottom surface portion 60. A soil collecting space surrounded by the bottom surface portion 60 and the pair of side surfaces 70 is formed inside the shells 15, 16. Soil is received by the bottom surface portion 60 inside the shells 15, 16. The bottom surface portion 60 has a vertical portion 61 including an edge portion located at the edge of the opening 50 of the shells 15, 16, and a curved portion 62 that curves and extends upward from the vertical portion 61.

[0025] The vertical portion 61 of the bottom portion 60 is disposed perpendicular to the horizontal plane when the pair of shells 15, 16 are disposed in the open position P2. The tip of the vertical portion 61 located at the tip of the bottom portion 60 is the first of the bottom portion 60 to contact the ground when excavating the ground. A plurality of excavation claws 63 are attached to the bottom portion 60. The plurality of excavation claws 63 are disposed at intervals from each other and protrude toward the ground from the tip of the vertical portion 61. By making the vertical portion 61 perpendicular to the horizontal plane when excavating the ground, the force applied from the bottom portion 60 to the ground acts along the vertical direction to the ground without being dispersed, and the force is efficiently transmitted from the bottom portion 60 to the ground. Therefore, the excavation claws 63 and the vertical portion 61 are easily inserted into the ground.

[0026] The bottom surface portion 60 has an upper edge plate 64 located at the upper edge of the bottom surface portion 60, an opening edge plate 65 located at the edge of the opening 50 of the shells 15, 16, and a bottom plate 66 located between the upper edge plate 64 and the opening edge plate 65. The bottom surface portion 60 is formed by the upper edge plate 64, the bottom plate 66, and the opening edge plate 65, which are connected to each other. The vertical portion 61 is a portion of the opening edge plate 65 of the bottom surface portion 60, and the curved portion 62 is a portion of the upper edge plate 64 and the bottom plate 66 of the bottom surface portion 60.

[0027] The upper edge plate 64 is a plate portion including the upper edge of the bottom surface portion 60, and the opening edge plate 65 is a plate portion including the edge of the opening 50. The bottom plate 66 is a plate portion that connects the upper edge plate 64 and the opening edge plate 65, and curves between the upper edge plate 64 and the opening edge plate 65. The upper edge plate 64 and the opening edge plate 65 are thick plate portions of the bottom surface portion 60 that are thicker than the bottom plate 66. The bottom plate 66 is a thin plate portion of the bottom surface portion 60 that is thinner than the upper edge plate 64 and the opening edge plate 65.

[0028] The side portion 70 has an upper edge plate 71 located at the upper edge of the side portion 70, an opening edge plate 72 located at the edge of the opening 50 of the shells 15, 16, and a side plate 73 located between the upper edge plate 71 and the opening edge plate 72. The side portion 70 is formed by the upper edge plate 71, the side plate 73, and the opening edge plate 72, which are connected to each other. The upper edge plate 71 of the side portion 70 is connected to the upper edge plate 64 of the bottom portion 60. The opening edge plate 72 of the side portion 70 is connected to the opening edge plate 65 of the bottom portion 60. The side plate 73 of the side portion 70 is connected to the bottom plate 66 of the bottom portion 60.

[0029] The upper edge plate 71 is a plate portion including the upper edge of the side surface portion 70, and the opening edge plate 72 is a plate portion including the edge of the opening 50. The side plate 73 is a plate portion connected to the upper edge plate 71 and the opening edge plate 72. The upper edge plate 71 and the opening edge plate 72 are thick plate portions of the side surface portion 70 that are thicker than the side plate 73. The side plate 73 is a thin plate portion of the side surface portion 70 that is thinner than the upper edge plate 71 and the opening edge plate 72. The rigidity of the shells 15, 16 is ensured by the thick plate portions of the upper edge plate 64 and the opening edge plate 65 of the bottom surface portion 60, and the upper edge plate 71 and the opening edge plate 72 of the side surface portion 70.

[0030] The movable body 30 moves vertically together with the connecting pin 31 above the openings 50 of the pair of shells 15, 16, and opens and closes the pair of shells 15, 16 while rotating the pair of shells 15, 16 around the center of the connecting pin 31. At that time, the movable body 30 applies a vertical force to the connecting portion of the pair of shells 15, 16 with the connecting pin 31 by the connecting pin 31. The pair of shells 15, 16 rotate around the center of the support pins 25, 26 between a closed position P1 and an open position P2 by the force received from the movable body 30, thereby opening and closing.

[0031] The clamshell bucket 5 rises when the lifting rope 10 and the opening / closing rope 11 are simultaneously wound up, and the clamshell bucket 5 descends when the lifting rope 10 and the opening / closing rope 11 are simultaneously let out. When the lifting rope 10 is stopped and the opening / closing rope 11 is let out, the moving body 30 moves downward, and the pair of shells 15, 16 rotate from the closed position P1 to the open position P2 and open due to the weight of the moving body 30. Also, when the lifting rope 10 is stopped and the opening / closing rope 11 is wound up, the moving body 30 moves upward, and the pair of shells 15, 16 rotate from the open position P2 to the closed position P1 and close.

[0032] When the excavator 1 is used to excavate the ground, the operator in the cab 8 performs the following operations to excavate the ground and load soil. First, the operator mainly operates the swing lever to move the clamshell bucket 5 directly above the excavation position on the ground. The main winding clutch lever and the catch winding clutch lever are placed in neutral, and the holding switches of the open / close winch and the support winch are turned off. With the main winding brake pedal and the catch winding brake pedal somewhat loosened, the clamshell bucket 5 is allowed to freely fall under its own weight. The descent speed of the clamshell bucket 5 is adjusted by the amount of operation of the main winding brake pedal and the catch winding brake pedal. The greater the amount of operation of the main winding brake pedal and the catch winding brake pedal, the greater the braking force of the open / close winch and the support winch, and the slower the descent speed of the clamshell bucket 5.

[0033] When the clamshell bucket 5 descends to a position of 2 to 3 m above the ground, the main winding clutch lever is operated to let out the opening / closing rope 11. As the opening / closing rope 11 is let out, the distance between the sheave 40 provided on the support 20 and the sheave 41 provided on the moving body 30 becomes longer, and the pair of shells 15, 16 rotate around the center of the support pins 25, 26 due to the weight of the moving body 30. As a result, the pair of shells 15, 16 are placed in the open position P2 and open. With the main winding brake pedal and the catch winding brake pedal somewhat loosened, the clamshell bucket 5 is allowed to freely fall under its own weight. At that time, the tension of the opening / closing rope 11 is adjusted to be smaller than the tension of the lifting rope 10, and the clamshell bucket 5 is allowed to descend without closing the pair of shells 15, 16.

[0034] The fact that the clamshell bucket 5 has landed is recognized by the slack in the lifting rope 10 and the opening / closing rope 11 stretched across the boom 4. After the clamshell bucket 5 has landed, the main winding brake pedal and the catch winding brake pedal are depressed to stop the descent of the clamshell bucket 5. The hoist lever is operated to the winding side to wind up only the opening / closing rope 11. As the opening / closing rope 11 is wound up, the distance between the sheave 40 provided on the support 20 and the sheave 41 provided on the moving body 30 becomes shorter, and the moving body 30 moves upward. As a result, the pair of shells 15, 16 rotate from the open position P2 to the closed position P1 to close, while excavating the ground.

[0035] After the pair of shells 15, 16 are completely closed, the hoist lever is operated to the hoist side and the opening / closing rope 11 is wound up while the lifting rope 10 is also wound up. This causes the clamshell bucket 5 to be lifted from the ground. Immediately after the pair of shells 15, 16 are closed, the lifting rope 10 is slack and the opening / closing rope 11 is taut, so the pair of shells 15, 16 rise without opening.

[0036] While the clamshell bucket 5 is rising, the tension of the opening / closing rope 11 is adjusted to be equal to or greater than the tension of the lifting rope 10, thereby maintaining the pair of shells 15, 16 in a closed state. The turning lever is mainly operated to move the clamshell bucket 5 to a soil-discharging position directly above the bed 13 of the dump truck 12. The main hoist clutch lever is operated to pay out the opening / closing rope 11 and allow the movable body 30 to freely fall. This opens the pair of shells 15, 16, and the soil is loaded onto the bed 13 of the dump truck 12.

[0037] The pair of shells 15, 16 in the closed position P1 are disposed facing each other across a vertical plane K that passes through the center of the connecting pin 31. The support pins 25, 26 are located on both the left and right sides of the vertical plane K at a distance from the vertical plane K and are disposed symmetrically with respect to the vertical plane K. The support body 20 supports each of the pair of shells 15, 16 by the support pins 25, 26 in the space on one side and the space on the other side of the vertical plane K. The support body 20 has a single-link structure, and supports one shell 15 by the support frame 21 in the space on one side of the vertical plane K and supports the other shell 16 by the link 22 in the space on the other side of the vertical plane K.

[0038] When the pair of shells 15, 16 are disposed in the closed position P1, the support pins 25, 26 are provided in each of the spaces on one side and the other side of the vertical plane K, at positions closer to the vertical plane K than the outer ends 51 of the pair of shells 15, 16 in an orthogonal direction H perpendicular to the vertical plane K. The orthogonal direction H is a horizontal direction perpendicular to the vertical plane K. The outer ends 51 of the shells 15, 16 are outer ends located on the opposite side of the vertical plane K of the shells 15, 16 in the orthogonal direction H. When viewed from their positions in the orthogonal direction H, the support pins 25, 26 and the link pin 28 are each spaced apart from the vertical plane K in the orthogonal direction H and disposed closer to the vertical plane K than the outer ends 51 of the shells 15, 16.

[0039] The upper edge plate 71 of the side surface portion 70 of the pair of shells 15, 16 extends obliquely upward from the outer end portion 51 of the shells 15, 16 toward the vertical plane K when the pair of shells 15, 16 are disposed in the closed position P1. The support pins 25, 26 are provided at a position on the upper edge plate 71 closer to the vertical plane K than the outer end portion 51 of the shells 15, 16, and are connected to the upper edge plate 71. The support pins 25, 26 are disposed at a position on the upper edge plate 71 between the outer end portion 51 of the shells 15, 16 and the vertical plane K, spaced apart from the outer end portion 51 of the shells 15, 16 and the vertical plane K.

[0040] Link pin 28 is disposed in a region between a horizontal plane passing through the top of sheave 40 provided on support 20 and a horizontal plane passing through the bottom of sheave 40, and is juxtaposed to sheave 40 when viewed from the axial direction of sheave 40, at a position within the region between the two horizontal planes. Link pin 28 is also provided at a position spaced away from the axial center of sheave 40 to the outside in the radial direction of sheave 40.

[0041] The support pin 26 attached to the link 22 is provided at a position closer to the vertical plane K than the outer end 51 of the shell 16 in the orthogonal direction H and closer to the outer end 51 of the shell 16 than the link pin 28 when the pair of shells 15, 16 are arranged in the closed position P1. When viewed from the position in the orthogonal direction H, the support pin 26 is spaced away from the outer end 51 of the shell 16 toward the vertical plane K and is arranged at a position farther from the vertical plane K than the link pin 28.

[0042] Fig. 4 is a front view showing an example of a conventional clamshell bucket 5A. Fig. 5 is a front view showing the change in height when the clamshell bucket 5 of this embodiment and the conventional clamshell bucket 5A are opened and closed. Fig. 5A is a front view showing the conventional clamshell bucket 5A. Figs. 5B and 5C are front views showing two examples of the clamshell bucket 5 of this embodiment. The positions of the support pins 25, 26 are different between the clamshell bucket 5 shown in Fig. 5B and the clamshell bucket 5 shown in Fig. 5C.

[0043] The conventional clamshell bucket 5A has a bracket 17 that protrudes from outer ends 51 of the pair of shells 15, 16. The support pins 25, 26 of the conventional clamshell bucket 5A are attached to the bracket 17 and disposed at positions outer than the outer ends 51 of the pair of shells 15, 16 in the perpendicular direction H. The configuration of the conventional clamshell bucket 5A other than the support pins 25, 26 and the bracket 17 is similar to the configuration of the clamshell bucket 5 of this embodiment.

[0044] When the pair of shells 15, 16 are disposed in the closed position P1, the conventional clamshell bucket 5A and the clamshell bucket 5 of this embodiment have the same height. However, the turning radius R1 of the shells 15, 16 in the conventional clamshell bucket 5A and the turning radius R2, R3 of the shells 15, 16 in the clamshell bucket 5 of this embodiment are different from each other. The turning radiuses R1, R2, R3 of the shells 15, 16 are linear distances from the centers of the support pins 25, 26 to the center of the connecting pin 31.

[0045] In the clamshell bucket 5 of this embodiment, the support pins 25, 26 are located closer to the vertical plane K than the outer ends 51 of the pair of shells 15, 16. As a result, the turning radii R2, R3 of the shells 15, 16 in the clamshell bucket 5 of this embodiment are smaller than the turning radius R1 of the shells 15, 16 in the conventional clamshell bucket 5A. In addition, when comparing the straight-line distances S1, S2, S3 parallel to the vertical portion 61 from the centers of the support pins 25, 26 to the tips of the bottom portion 60, the straight-line distances S2, S3 in the clamshell bucket 5 of this embodiment are shorter than the straight-line distance S1 in the conventional clamshell bucket 5A.

[0046] When the pair of shells 15, 16 are disposed in the open position P2, the height of the clamshell bucket 5 of this embodiment is lower than the height of the conventional clamshell bucket 5A due to the difference in the positions of the support pins 25, 26. As the positions of the support pins 25, 26 approach the vertical plane K, the turning radii R1, R2, R3 and the linear distances S1, S2, S3 become smaller, and the height of the clamshell buckets 5A, 5 becomes lower.

[0047] As shown in Fig. 5B, the winding force of the opening / closing rope 11 is F. The linear distance from the center of the support pins 25, 26 to the tip of the bottom surface portion 60 is Lb, and the distance in the perpendicular direction H from the center of the support pins 25, 26 to the vertical plane K is Lc. If the number of sheaves 40 provided on the support body 20 is n, the number of sheaves 41 provided on the moving body 30 is n+1. In this case, the force Qb applied to the connecting pin 31 is calculated by the formula Qb = F x 2 (n + 1). The excavation force Pb applied to the tip of the bottom surface portion 60 against the ground is calculated by the formula Pb = Qb x (Lc / Lb).

[0048] As can be seen from the calculation formula for the excavation force Pb, when the winding force F of the opening / closing rope 11 is the same, the excavation force Pb increases as the support pins 25, 26 move away from the vertical plane K and the distance Lc in the perpendicular direction H from the center of the support pins 25, 26 to the vertical plane K increases. In contrast, the excavation force Pb decreases as the support pins 25, 26 move closer to the vertical plane K and the distance Lc decreases. Also, the excavation force Pb decreases as the linear distance Lb from the center of the support pins 25, 26 to the tip of the bottom surface portion 60 increases.

[0049] Generally, the number n of sheaves 40 is 2, and the number n+1 of sheaves 41 is 3. In contrast, by increasing the number n of sheaves 40 in accordance with the positions of the support pins 25, 26, the excavation force Pb increases. The number n+1 of sheaves 41 increases by the same number as the increased number of sheaves 40. By increasing the number n of sheaves 40, an excavation force Pb equivalent to that of the conventional clamshell bucket 5A is ensured in the clamshell bucket 5 of this embodiment. In addition, by changing the number n of sheaves 40 and the number n+1 of sheaves 41, the movement speed of the movable body 30 and the closing speed of the pair of shells 15, 16 are adjusted.

[0050] According to this embodiment, for example, the following advantageous effects are obtained.

[0051] When viewed from the position in the orthogonal direction H, the support pins 25, 26 of the clamshell bucket 5 are located closer to the vertical plane K than the outer ends 51 of the pair of shells 15, 16. This reduces the rotation radii R2, R3 of the pair of shells 15, 16. Also, when the pair of shells 15, 16 are disposed in the open position P2, the height of the clamshell bucket 5 is lowered. Therefore, the difference in height of the clamshell bucket 5 when the pair of shells 15, 16 are open and closed can be made smaller than that of the conventional clamshell bucket 5A.

[0052] When loading soil and sand onto the bed 13 of the dump truck 12, the position of the clamshell bucket 5 can be lowered and the pair of shells 15, 16 can be prevented from contacting the bottom of the bed 13. As a result, damage to the bottom of the bed 13 can be prevented. Furthermore, the clamshell bucket 5 can be easily used even at a construction site where the working height is limited. When the pair of shells 15, 16 are placed in the open position P2 and the clamshell bucket 5 is placed on the ground, the height of the clamshell bucket 5 from the ground is lowered. Therefore, maintenance work such as tying a rope to the clamshell bucket 5 and greasing each pin can be easily performed.

[0053] Since there is no need to provide brackets or support pins 25, 26 at positions outside the outer ends 51 of the pair of shells 15, 16, it is possible to prevent the clamshell bucket 5 from hitting an obstacle. Therefore, deformation of the support pins 25, 26 can be suppressed, and the pair of shells 15, 16 can be stably opened and closed. The link pin 28 is provided in parallel with the sheave 40 in the region between a horizontal plane passing through the uppermost part and a horizontal plane passing through the lowermost part of the sheave 40 provided on the support body 20. This allows the shell 16 supported by the link 22 to be located at an upper position, thereby lowering the height of the clamshell bucket 5.

[0054] When viewed from the position in the orthogonal direction H, the support pin 26 is provided at a position closer to the vertical plane K than the outer end 51 of the shell 16 and closer to the outer end 51 of the shell 16 than the link pin 28. This makes it possible to reduce the difference in height of the clamshell bucket 5 when the pair of shells 15, 16 are opened and closed, while maintaining the excavation force of the shell 16 against the ground. In addition, the winding force F of the opening / closing rope 11 can be efficiently converted into an excavation force Pb. By bringing the link 22 closer to the vertical plane K, it is also possible to prevent the link 22 from contacting an obstacle.

[0055] Since the support pins 25, 26 are provided at a position closer to the vertical plane K than the outer end 51 of the upper edge plate 71, it is possible to shorten the linear distances S2, S3 parallel to the vertical portion 61 from the centers of the support pins 25, 26 to the tip of the bottom portion 60. This makes it possible to reduce the change in the up-down position of the tip of the bottom portion 60 when the shells 15, 16 rotate, and to reduce the difference in height of the clamshell bucket 5 when the pair of shells 15, 16 are opened and closed.

[0056] The thick upper edge plate 71 and the opening edge plate 72 ensure the rigidity of the side surface portions 70 of the shells 15, 16. By connecting the support pins 25, 26 to the upper edge plate 71, the strength of the connection between the support pins 25, 26 and the shells 15, 16 can be ensured.

[0057] The clamshell bucket 5 of this embodiment is configured with parts equivalent to those of the conventional clamshell bucket 5A. Therefore, it is possible to suppress an increase in the weight of the clamshell bucket 5. The clamshell bucket 5 of this embodiment can be attached to a conventional excavator equipped with a conventional clamshell bucket 5A in place of the conventional clamshell bucket 5A and used without modifying the conventional excavator.

[0058] In addition, a soil discharge device may be provided inside the pair of shells 15, 16, and the soil discharge device may scrape off soil and sand inside the shells 15, 16 when the shells 15, 16 rotate from the closed position P1 to the open position P2. The excavation claws 63 may not be attached to the pair of shells 15, 16.

[0059] The support 20 is not limited to a single-link structure, and may be a double-link structure. In the support 20 of the double-link structure, a link is provided on the support 20 instead of the support rod 27 of the support frame 21. The link extends obliquely downward from the support frame 21 to one shell 15, and is rotatably connected to the support frame 21 by a link pin and is rotatably connected to the shell 15 by a support pin 25. The support 20 supports one shell 15 by a first link connected to one shell 15 in a space on one side of the vertical plane K, and supports the other shell 16 by a link 22, which is a second link connected to the other shell 16, in a space on the other side of the vertical plane K.

[0060] In each of the above-mentioned embodiments, the present invention has been described as being applied to an excavator 1 based on a crawler crane, but the present invention can also be applied to the clamshell bucket of other types of excavators and achieves similar effects. An excavator to which the clamshell bucket of the present invention can be applied is, for example, an excavator equipped with a telescopic boom or arm that uses a rope to raise and lower and open and close the clamshell bucket.

[0061] The above-described embodiments are merely examples for explaining the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the gist of the present invention. [Explanation of symbols]

[0062] 1. Excavator 5 Clamshell Bucket 10 Ascending and descending rope 11 Opening and closing rope 15 Shell 16 Shell 20 Support 21 Support frame 22 Links 25 Support pin 26 Support pin 27 Support Rod 28 Link pin 30 Mobile 31 Connecting pin 40 Sheaves 41 Sheaves 50 Opening 51 Outer end 60 Bottom part 61 Vertical section 62 Curved section 70 Side part 71 Upper edge plate 72 Opening edge plate 73 Side Panel H Orthogonal direction K vertical plane P1 closed position P2 open position

Claims

1. a pair of openable and closable shells that rotate between a closed position in which the openings face each other and an open position in which the openings are spaced apart; a movable body that is above the openings of the pair of shells that are disposed at the closed position and that rotatably connects the pair of shells by a connecting pin and moves in a vertical direction to open and close the pair of shells; a support body that supports the shell rotatably between the closed position and the open position by a support pin in each of a space on one side and a space on the other side of a vertical plane passing through a center of the connecting pin; A clamshell bucket including a sheave provided on each of the moving body and the support, and around which a rope for moving the moving body in a vertical direction is wound, The shell has a bottom surface and a pair of side surfaces protruding from the bottom surface and facing each other, The side surface portion has an upper edge plate located at an upper edge portion and extending from an outer end portion of the shell toward the vertical surface, an opening edge plate located at an edge portion of the opening, and a side plate located between the upper edge plate and the opening edge plate, The upper edge plate is a thick plate portion that is thicker than the side plates, When the pair of shells are disposed in the closed position, the support pin is provided in each of the one-side space and the other-side space at a position closer to the vertical plane than the outer end of the upper edge plate of the pair of shells in a direction perpendicular to the vertical plane, The support includes a support frame and a link connected to the support frame by a link pin and connected to the shell by the support pin; The clamshell bucket, wherein the support pin is provided at a position on the upper edge plate closer to the vertical plane than the outer end in the orthogonal direction and closer to the outer end than the link pin.

2. 2. The clamshell bucket of claim 1, The link pin is disposed on a horizontal plane passing through the uppermost portion of the sheave provided on the support and a lowermost portion of the sheave. The sheave is provided in parallel with the sheave provided on the support in the region between the horizontal planes passing through the The distinctive clamshell bucket.

3. 2. The clamshell bucket of claim 1, The opening edge plate is a thick plate portion that is thicker than the side plate, The clamshell bucket, wherein the support pin is connected to the upper edge plate.

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