EP2484837B1 - Grapple provided with a bucket comprising a shutter - Google Patents

Description

Background of the invention

The present invention relates to the field of soil excavation tools, and more particularly excavation machines type grab.

Clams, also called buckets, are generally used to make walls in the ground, for example molded or prefabricated walls. They can also be used to make sealing screens or bars.

Clamshells traditionally comprise a frame which are articulated two buckets, also called "pockets", arranged symmetrically with respect to a vertical plane. Each bucket conventionally consists of two side walls that extend on either side of a concave geometry back, so as to form a kind of trough. The buckets can be swiveled by pivoting arms, actuated by jacks or cables, to open and close the clamshell.

The clamshell is mounted on a vehicle by being attached to the lower end of levitation means, for example a Kelly bar and / or lift cables. To make a trench, the clamshell is first opened before being lowered to the ground to be excavated. Then the clamshell is closed so as to destructure the ground and grab a volume of soil excavated between the two buckets. The grab is then lifted to evacuate the excavated soil. Such a grab is for example disclosed in the documents JP-A-2005336840 and US 6,446,364 .

It should be noted that the excavation operation can be carried out by injection of drilling mud, for example a bentonite slurry or cement bentonite slurry. An interest of the mud is to support the trench to prevent it from collapsing on itself.

To date, there are two clamshell bucket technologies: closed geometry buckets and open geometry buckets. The open-geometry bucket differs from the closed-geometry bucket in that it has large openings or passages allowing the drilling mud to pass as the grab bucket descends into the trench.

It is therefore clear that the advantage of an open geometry grab is to have a higher vertical (up / down) movement speed than a closed geometry grab while decreasing the piston effect of the bucket. the trench. However, at equal dimensions, the open geometry grab has the disadvantage of containing a volume of excavated soil substantially less than that of a closed geometry grab.

The reason is that the excavated soil tends to escape from the buckets as it flows through the openings when closing the grab.

Object and summary of the invention

An object of the invention is to provide a clamshell equipped with a bucket having a vertical movement speed greater than that of a clamshell equipped with a closed geometry bucket, while providing an excavation volume greater than that of a conventional grab bucket equipped with an open geometry bucket.

This object is achieved by means of a grab bucket comprising two side walls which extend perpendicularly on either side of a concave geometry back, said back being provided with at least one opening, the grab bucket further comprising at least one shutter having an open position in which the opening is open, and a closed position in which the opening is closed by the shutter.

Thus, the bucket can have an open geometry when the shutter is in the open position, and a geometry closed when the shutter is in the closed position. In other words, the bucket has a variable geometry.

During the descent of a grab bucket equipped with such buckets, the shutter of each bucket is brought into the open position so that the drilling mud can flow widely through the opening.

When the grab has reached the bottom of the trench, the shutter of each bucket is brought to the closed position so that the opening is closed. Subsequently, or simultaneously, the buckets pivot to close the grab. As the openings are closed, the excavated soil can not flow out of the buckets. So the grab can excavate a volume of soil greater than that a grab bucket whose buckets are open geometry. An interest is to improve the volume capacity of the grab and, consequently, to reduce the number of lifts and descents made by the grab. In other words, the invention makes it possible to significantly improve the speed of realization of the trench.

Furthermore, the back of the bucket has a cutting edge orthogonal to the side walls, and the opening is preferably located at one end of the back which is opposite to the cutting edge. An advantage of this particular provision of the opening is to allow better circulation of the drilling mud during the descent of the grab.

This cutting edge is located at the end of the back that is opposite the opening. Conventionally, this cutting edge is provided with cutting teeth.

Optionally, the back further comprises an orifice formed between said at least one opening and the cutting edge. When it exists, this orifice has dimensions substantially smaller than those of the opening. An interest of this light is to facilitate the flow of the drilling mud out of the buckets during the ascent of the grab.

Advantageously, the length of the opening corresponds substantially to the distance between the two side walls, while the width of the opening is preferably between one sixth and one third of the length of the back. Thanks to this particular conformation, the drilling mud has a large passage to flow during the descent of the clamshell without too weaken the mechanical strength of the bucket.

According to a preferred embodiment the shutter is fixed to the bucket pivotally. The shutter therefore acts as a pivoting valve that closes the opening in the back.

Preferably, the displacement of the shutter is achieved without additional actuator, that is to say without motor or additional cylinder. For example, the shutter comprises a body provided with at least one wing projecting perpendicularly from the body, said wing having an oblong and curved slot to receive a stud attached to an arm of the grab. When pivoting the bucket according to the invention, the pin moves relative to the bucket. As the nipple is housed in the light oblong, the displacement of the pin causes the pivoting of the shutter about its axis of rotation, and thus its closing or opening.

It is therefore clear that, thanks to this particular kinematics, it is advantageously possible to actuate the shutter without providing dedicated motor means, which ensures the reliability of the shutter mechanism of the opening. Nevertheless, it would be quite possible to control the displacement of the shutter using an electric motor, a cylinder or any other equivalent actuator, which would be placed on the bucket or on the clamshell. A clamshell according to the present invention is defined in claim 1 and comprises at least one bucket as defined above, and means acting on the shutter of said bucket to move it between its open position and its closed position. The shutter is pivotally attached to the bucket, and the clamshell has means acting on the shutter to rotate it between its open position and its closed position. The clamshell has a frame and at least one arm cooperating with the shutter, the bucket is pivotally attached to the frame, the arm has a first end pivotally attached to the bucket and a second end pivotally attached to the frame, the bucket having an open state and a closed state, and the shutter is arranged to be in the open position when the bucket is in the open state, and in the closed position when the bucket is in the closed state. The means for pivoting the shutter comprises the arm, so that the movement of the arm causes the bucket and the shutter to pivot simultaneously.

In one example, the shutter is pivotally mounted relative to the bucket, the shutter comprising a body provided with at least one wing extending perpendicularly from the body, said wing having an oblong and curved slot receiving a stud fixed to the arm clamshell, so that the opening and closing of the shutter are controlled by the movement of the arm. The shutter in the open position extends in a substantially vertical plane.

In one example, the back of the bucket has a cutting edge orthogonal to the side walls, and the opening is located at an end of the back that is opposite to the cutting edge.

According to a preferred embodiment, the opening opens at a free end of the back, and the shutter, which constitutes a removable portion of the back, is, in the closed position, located in the extension of the remaining portion, fixed back .

Optionally, the back further comprises an orifice formed between said at least one opening and the cutting edge.

The length of the opening may for example correspond substantially to the distance between the two side walls.

The width of the opening can be between one sixth and one third of the length of the back.

The present invention also relates to a use of a grab bucket according to the invention for producing a trench under slurry injection.

• on ouvre la benne preneuse en faisant pivoter les godets pour les amener dans leur état ouvert ;
• on amène les obturateurs des godets dans leur position ouverte ;
• on descend la benne preneuse dans la tranchée, la tranchée contenant de la boue de forage ;
• lorsque la benne preneuse est arrivée au fond de la tranchée, on ferme la benne preneuse en faisant pivoter les godets pour les amener dans leur état fermé ;
• on amène les obturateurs des godets dans leur position fermée ;
• on remonte la benne preneuse.

The invention finally relates to a method of excavating a trench in a soil using a grab bucket according to the invention comprising two buckets, in which process:

• the clamshell is opened by rotating the buckets to bring them into their open state;
• the shutters of the buckets are brought into their open position;
• the clamshell is lowered into the trench, the trench containing drilling mud;
• when the grab has reached the bottom of the trench, the clamshell is closed by rotating the buckets to bring them into their closed state;
• the shutters of the buckets are brought into their closed position;
• we go up the grab.

Brief description of the drawings

• la figure 1 représente une benne preneuse conforme à l'invention lors de son introduction dans le sol, la benne comportant deux godets munis d'obturateurs, les godets étant dans l'état ouvert et les obturateurs étant en position ouverte;
• la figure 2 représente la benne preneuse de la figure 1 au cours de la fermeture des godets ;
• la figure 3 illustre la remontée de la benne preneuse de la figure 2 , les godets étant dans l'état fermé et les obturateurs étant en position fermée ;
• la figure 4 est une vue en perspective de dessus des deux godets de la benne de la figure 1 , montrant les obturateurs en position ouverte ;
• la figure 5 est une vue en coupe latérale d'un godet tel que celui de la figure 4, l'obturateur étant en position fermée; et
• la figure 6 est une vue éclatée du godet de la figure 5 .

The invention will be better understood on reading the following description of an embodiment of the invention given by way of non-limiting example, with reference to the appended drawings, in which:

• the figure 1 represents a clamshell according to the invention during its introduction into the ground, the bucket comprising two buckets provided with shutters, the buckets being in the open state and the shutters being in the open position;
• the figure 2 represents the grab bucket of the figure 1 during the closing of the buckets;
• the figure 3 illustrates the ascent of the grab bucket of the figure 2 , the buckets being in the closed state and the shutters being in the closed position;
• the figure 4 is a perspective view from above of the two buckets of the bucket of the figure 1 , showing the shutters in the open position;
• the figure 5 is a side sectional view of a bucket such as that of the figure 4 with the shutter in the closed position; and
• the figure 6 is an exploded view of the bucket of the figure 5 .

The clamshell 10 illustrated on the figure 1 comprises a frame 12 which is intended to be fixed to the lower end of levitation means preferably comprising a guide shaft 14, also called "Kelly" The set with or without kelly and generally suspended at the end of a or more cables 15. The bucket 10 further comprises a pair of buckets 16, 18, also called "pockets", which are hinged to the frame 12.

More specifically, buckets 16, 18 are mounted to the frame so as to be pivotable about two horizontal axes of rotation 20,22 arranged at the lower end 12a of the chassis 12. The clamshell bucket 10 further comprises a pair of arms 26, 28, each of the arms 26, 28 having a first end 26a, 28b pivotally attached to one of the buckets, and a second end 26b, 28b pivotally attached to the frame 12 . In this example, the two arms 26, 28 are pivotally mounted relative to the frame 12 about the same axis of rotation A. In the example, the axis of rotation A is freely mounted in translation within an oblong hole formed in the frame 12 and extending vertically as shown in dotted line on the figures 1 , 2 and 3 .

The buckets 16, 18 are pivotally mounted at the ends 26a, 28a of the arms 26, 28 which are opposed to the axis of rotation A. More exactly, the buckets 16, 18 can pivot relative to the arms around the axes referenced 30, 32.

The bucket 10 finally comprises cylinders 34, 36 pivotally mounted to the frame 12 on the one hand, and the arms 26, 28 on the other hand. The actuation of the cylinders 34, 36 makes it possible to pivot the arms 26, 28 around the axis A, the pivoting of the arms 26, 28 causing the buckets to pivot about the axes 20, 22. It is specified here that these jacks can quite be replaced by pull cables connected to the ends of the arms. The use of cylinders is therefore not an essential element of the invention.

Each of the buckets 16, 18 thus has an open state and a closed state, the bucket being brought from the open state to the closed state by pivoting the arm to which it is attached. Specifically, the open state is obtained when the cylinder 34, 36 associated is retracted, while conversely the closed state is obtained when the cylinder is deployed. The buckets 16, 18 can be operated independently, so that one can be in the open state, while the other is in the closed state.

The Figures 1 to 3 illustrate the excavation process according to the invention.

On the figure 1 , the clamshell 10 is shown during its descent into the trench T during excavation. It should be noted that the trench is conventionally filled with drilling mud by injection means not shown here. This drilling mud has the particular function of maintaining a hydrostatic pressure on the wall of the trench to prevent it from collapsing on itself.

As shown on the figure 1 , the two buckets 16 and 18 are generally in the open state during the descent of the clamshell in the trench T. The span of the grab is therefore substantially equal to the width LT of the trench T.

According to the invention, each of the buckets 16, 18 comprises an opening 38, 40 that can be closed by a shutter 42, 44. Each bucket therefore comprises at least one shutter 42, 44 having an open position in which the opening 38, 40 is open, and a closed position in which the opening 38, 40 is closed by the shutter 42, 44.

During the vertical descent of the grab bucket 10, the two buckets are in the open state, while the shutters 42 and 44 are in the open position. This is clearly visible on the figure 1 . Consequently, the drilling mud can flow through the openings 38, 40 during the descent of the grab bucket 10, which greatly facilitates the descent of the grab into the trench filled with sludge. The flow of mud through the openings is shown schematically by the arrows bearing the reference F.

In other words, when the shutters are in the open position, the buckets oppose substantially less resistance to the descent of the grab and reduce the piston effect and its adverse consequences.

When the clamshell 10 reaches the bottom of the trench T, as illustrated in FIG. figure 2 , the jacks are actuated so as to close the buckets 16, 18. In this figure, the buckets are shown in an intermediate state between the open state and the closed state. When they are closed, the buckets come to bite the ground located at the bottom of the trench after which excavated soil cuttings, mixed with the mud, enter the buckets 16, 18.

During the rotation of the buckets, the shutters are actuated so as to close the openings 38, 40. In the example of the figure 2 , The shutters are shown in an intermediate position between their open position and their closed position.

The figure 3 shows the clamshell 10 when it rises to the surface. As seen, the two buckets 16, 18 are in their closed state, and the shutters 42, 44 are in the closed position so that the openings 38, 40 are closed. As can be understood from this figure, the closure of the openings makes it possible to increase the volume V of cuttings that the buckets can hold, compared to a bucket without a shutter. Indeed, in the absence of the shutters, the cuttings could flow through the openings 38, 40, which would limit the volume of cuttings that the buckets could contain, as a result of which it would be necessary to perform more round trip to evacuate the same volume of cuttings.

With the help of Figures 4 to 6 , we will now describe in more detail the structure of the buckets according to the invention, as well as the operation of the shutters.

Each bucket 16, 18 comprises two lateral walls 16a, 16b, 18a, 18b which extend perpendicularly from one side to the other of a concave geometry back 46, 48.

The openings 38, 40 are located in the concave geometry back 46, 48 of the buckets 16, 18. In this example, the openings 38, 40 are formed in one of the faces 50, 52 of the concave geometry of the cups 16 , 18, and extend between the two side walls of the buckets so that the length L of each of the openings here corresponds to the distance between the two side walls.

It is also noted that each of the buckets has a cutting edge 16c, 18c, provided with teeth, which is orthogonal to the side walls 16a, 16b, 18a, 18b. As we see better on the figure 4 , the opening 40 is located at one end of the back 48 which is opposite to the cutting edge 18c.

In the embodiment presented here, the width 1 of each of the openings 38, 40 corresponds to about three quarters of the length of the face 50, 52 of the back. In addition, the width l of the openings is less than one third of the total length of the back, but greater than one sixth of this total length. In addition, for each of the buckets, the opening 38, 40 opens at the end of said face 50, 52 so as to communicate with another opening 54, 56 defined between the two side walls 16a, 16b, 18a, 18b and extending it along the edges connecting said face 50, 52 to the axis of rotation 20, 22.

Furthermore, the side walls of each bucket have edges provided with points, said edges extending perpendicularly to either side of the cutting edge.

The figure 4 is a top view, in section, of the clamshell when the two buckets 16, 18 are open. This bucket configuration therefore corresponds to the figure 1 wherein the grab bucket 10 is lowered into the trench T. In this configuration, the valves 42, 44 are in the open position, and extend outwardly of the cup. As can also be seen on the figure 1 These shutters are preferably oriented so as to extend in a substantially vertical plane so as not to oppose resistance to the flow of the sludge F which is caused by the descent of the grab.

To facilitate the evacuation of the sludge when raising the grab, the back 46, 48 of each bucket further comprises an orifice 58, 60 formed in the same face 50, 52 as that in which the opening is located. 38, 40. Of course, the surface of the orifice is much smaller than that of the opening.

With the help of Figures 5 and 6 , we will now describe in more detail the shutter 44 of the bucket 18, that of the bucket 16 being identical.

The shutter 44 has a body 70 having a generally rectangular geometry. The length a and the width b of the shutter 44 substantially correspond to the length L and the width l of the opening 40. It is thus clear that when the shutter is in the closed position, the body 70 extends into the opening 40 to seal it. This shutter 44 can therefore also be seen as constituting a removable portion of the back 48.

The body 70 is provided with at least one wing, in this case two wings 72, 74 which protrude perpendicularly from the body towards the inside of the cup 18.

The wings extend along the width b of the body and each comprise a curved oblong slot 76, 78 whose function will be explained below.

According to an advantageous aspect of the invention, the shutter 44 is fixed to the bucket 18 pivotally.

To do this, the shutter 44 is pivotally mounted relative to the support 80 which carries the axis of rotation 32 around which the bucket 18 can pivot relative to the arm 28. As can be seen in the Figures 5 and 6 , the support 80 is fixed to the back 48 of the bucket 18 and more precisely to the face 52 of the back 48, while being housed inside the bucket 18. It is also noted that when the shutter 44 is in the closed position, the wings 72, 74 flank the support 80.

The support 80 comprises at least one rod 82, preferably two, which cooperates with one or two sleeves 84 integral with the shutter 44. It is understood that the sleeve 84 and the rod 82 form a hinge allowing the pivoting of the shutter 44 compared to the bucket according to an axis of rotation B perpendicular to the walls 18a, 18b of the bucket. The pivoting movement of the shutter 44 is also visible on the Figures 1 to 3 . Referring to these figures, it is found that the amplitude of rotation of the shutter 44 between the closed position and the open position is about a quarter turn. Thus, in the open position, the shutter is substantially orthogonal to the back 48.

According to the invention, the clamshell 10 comprises means acting on the shutters to move them between their open position and their closed position. In the embodiment shown here, these means are controlled means for rotating the shutters between their open position and their closed position.

The means for rotating the shutters comprise at least one, preferably two pins 86, 88, 90, 91 which are fixed to each of the arms 26, 28. If one is more particularly interested in the bucket 18 (the other bucket being identical), it is found that the pins 86, 88 extend coaxially on either side of the lower end 26a, 28a of the arm, along an axis parallel to the axis of rotation B of the shutters. As we see on the figure 4 These studs 86, 88 are arranged such that they cooperate with oblong slots and curves 76, 78 aforementioned.

The rotation of one of the arms 26, 28 of the grab bucket 10 causes the bucket 18 to pivot relative to the frame 12 about the axis 22, as well as the pivoting of the support 80 of the bucket 18 with respect to the arm 28 around of the axis 32. The pivoting of the support 80 causes the displacement of the pins 86, 88 relative to the bucket. As the lights 76, 78 receive the nipples 86, 88, it is understood that the nipples move in the lights during the pivoting of the arm 28. The lights 76, 78 act in some way as cams, and the movement of the nipples swing the shutter 44 about its axis of rotation B. The curvature and the length of the oblong slots is determined so that the shutter 44 is in the open position when the bucket is in the open state, and in the closed position when the bucket is in the closed state.

The arm 28 thus cooperates with the shutter 44 to rotate it, here via the pins 86, 88. It is understood that the opening and closing of the shutter 44 are controlled by the movement of the arm 28.

The kinematics of the displacement of the pin 88 in the oblong slot 78 is understood by referring to the Figures 1 to 3 which show in detail the position of the shutter 44 in the open, intermediate and closed position.

Claims (9)

1. A clamshell grab (10) including:

   a frame (12),

   at least one bucket comprising two side walls (16a, 16b, 18a, 18b) that extend perpendicularly on either side of a back (46, 48) of concave shape, said back being provided with at least one opening (38, 40), and the bucket further including at least one shutter (42, 44) presenting an open position in which the opening is open and a closed position in which the opening is closed by the shutter, the shutter being pivotally fastened to the bucket,

   an arm (26, 28) comprising a first end (26a, 28a) pivotally fastened to the bucket and a second end (26a, 28a) pivotally fastened to the frame,

   wherein the bucket presents an open state and a closed state, and the shutter (42, 44) is arranged so as to be in its open position when the bucket is in the open state, and in its closed position when the bucket is in the closed state,

   the bucket being pivotally fastened to the frame, the clamshell grab (10) being characterized in that it further includes means (28, 76, 78, 86, 88) acting on the shutter to pivot it between its open position and its closed position,

   in that the means for causing the shutter to pivot comprise said arm, such that moving the arm causes the bucket and the shutter to pivot simultaneously, the shutter (42, 44) finding itself, in the open position, in a substantially vertical plane.
2. A clamshell grab according to claim 1, wherein the shutter (42, 44) extends towards the outside of the bucket when it is in its open position.
3. A clamshell grab according to claim 1 or claim 2, characterized in that the shutter comprises a body (70) fitted with at least one flange (72, 74) extending perpendicularly from the body, said flange including a curved oblong slot (76, 78) receiving a stud that is fastened to the arm of the clamshell grab such that opening and closing of the shutter (42, 44) are controlled by moving the arm (26, 28).
4. A clamshell grab according to any one of claims 1 to 3, characterized in that the back of the bucket presents a cutting edge (16c, 18c) orthogonal to the side walls, and in that the opening is situated at an end of the back that is remote from the cutting edge.
5. A clamshell grab according to any one of claims 1 to 4, characterized in that the back further includes an orifice (58, 60) formed between said at least one opening and the cutting edge.
6. A clamshell grab according to any one of claims 1 to 5, characterized in that the length (L) of the opening (38, 40) corresponds substantially to the distance between the two side walls.
7. A clamshell grab according to any one of claims 1 to 6, characterized in that the width (ℓ) of the opening (38, 40) lies in the range one-sixth to one-third of the length of the back.
8. The use of a clamshell grab (10) according to any one of claims 1 to 7 for excavating a trench (T) with injection of mud.
9. A method of excavating a trench (T) in ground using a clamshell grab (10) according to any one of claims 1 to 8 including two buckets (16, 18), wherein:

   • the clamshell grab is opened by pivoting the buckets to bring them into their open state;

   • the shutters of the buckets are brought into their open positions;

   • the clamshell grab is lowered into the trench, the trench containing drilling mud;

   • when the clamshell grab reaches the bottom of the trench, the clamshell grab is closed by pivoting the buckets so as to bring them into their closed state;

   • the shutters of the buckets are brought into their closed positions; and

   • the clamshell grab is raised.

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