EP0593355A1 - Trenching apparatus for digging deep trenches with cutting drums - Google Patents

Abstract

The invention relates to apparatus for digging deep trenches in the ground, including a chassis equipped with cutting drums at its lower part. The upper part (3a) of the chassis (3) is provided with at least one guide member (6) which includes, in the direction parallel to the axes (5) of the milling drums (4) ends (7, 8) separated by a constant distance substantially equal to the thickness of the trench (1), and which, during the operation of the apparatus, can assume a centred position in which the upper part (3a) of the chassis is situated substantially equidistant from the two ends (7, 8) of the guide member (6), a position offset on one side of the chassis (1) in which the upper part (3a) of the chassis is brought closer to one (7) of the ends of the guide member (6) by a predetermined distance, and an offset position on the other side of the chassis (3) in which the upper part (3a) of the chassis is brought closer to the other end (8) of the guide member (6) by a predetermined distance. <IMAGE>

Description

The present invention relates to an apparatus for digging deep trenches in the ground using milling drums.

We already know of such devices in which a chassis supported by cables is provided at its lower part with two milling drums which rotate in opposite directions to break up the ground and dig a trench while the chassis is sinking into the ground.

Devices of this type can dig trenches, the depth of which is generally of the order of a few tens of meters, but which can reach up to about 150 meters.

So that the walls of a trench thus produced have good verticality, it is advantageous to be able to properly position the chassis of the device when it descends into the ground.

It is known to easily modify the inclination of the chassis in the direction perpendicular to the axes of the milling drums, by creating a difference in rotational speed between the latter.

On the other hand, in the direction parallel to the axes of the milling drums, the inclination of the chassis is controlled using devices such as lateral pushers which are not entirely satisfactory, in particular because of their low positioning accuracy.

The present invention aims to provide a simple and economical device which can be guided reliably and precisely in a trench in progress.

The subject of the present invention is an apparatus for digging deep trenches in the ground comprising a chassis provided with milling drums at its lower part, characterized in that the upper part of the chassis is provided with at least one guide which comprises, in the direction parallel to the axes of the milling drums, two ends spaced apart by a constant distance substantially equal to the thickness of the trench, and which can take, during the operation of the apparatus, a position centered in which the upper part of the chassis is located approximately equidistant from the two ends of the guide member, a position offset from one side of the chassis in which the upper part of the chassis is brought closer to one of the ends of the guiding by a predetermined distance, and a position offset from the other side of the chassis in which the upper part of the chassis is brought closer to a predetermined distance from the other end of the guide member.

In a preferred embodiment of the invention, the guide member comprises sliding pads at each of its ends so as to facilitate the sliding of the chassis during its descent or its ascent in the trench.

We understand that, thanks to the invention, we can at will keep the chassis of the device parallel to the walls of the trench, or tilt it to change the direction of digging, in case the device deviates from the path, generally vertical, that we want to follow.

To this end, since the lower part of the chassis, which supports the milling drums, remains substantially centered with respect to the trench, it suffices to move the upper part of the chassis laterally by maneuvering the guide member to orient the device in a given direction.

Tests carried out by the applicant have shown that, surprisingly, it was possible to properly guide the chassis of an apparatus according to the invention although the latter can only take three positions relative to the trench.

The apparatus according to the invention has the advantage that its chassis is permanently guided in the trench, whatever the position of the guide member relative to the chassis.

Indeed, the width of the guide member being substantially equal to the thickness of the trench, it is avoided that too much lateral play appears and lead to improper positioning of the chassis.

In a preferred embodiment of the invention, the guide member consists of a three-position hydraulic cylinder mounted on the chassis and the piston rod of which extends over the entire thickness of the chassis.

In such an actuator, the piston rod comprises an annular flange which seals between two annular chambers located on either side of the actuator into which a pressurized fluid is introduced to maneuver the actuator.

In a preferred variant, such a jack comprises an axially movable stop which is suitable, when it is subjected to the thrust of a fluid under pressure, to be positioned so as to limit the stroke of the piston rod between a first end-of-travel position at one end of the jack and an intermediate position bearing on the movable stop, and, when it is not subject to no fluid thrust, to move freely with the piston rod to allow the latter to reach its second end-of-travel position at the other end of the cylinder.

Advantageously, the movable stop is in the form of a cylinder section which is housed around the piston rod, on one side of the flange of the latter.

The movable stop, which thus undergoes the thrust of the pressurized fluid used to control the jack, delimits a sealed annular chamber between itself and said flange.

In this case, the cylinder body has an additional fluid intake orifice which opens into the annular volume between the movable stop and the flange of the piston rod.

To limit the stroke of the piston rod, the movable stopper is preferably positioned substantially in the central part of the cylinder body, which for this purpose comprises a bearing on which a projecting part of the movable stopper rests when the latter is subject to fluid thrust.

The movable stop has a fluid cross section greater than that of the annular flange of the piston rod so that, when the rod is held in the intermediate position against the movable stop, the thrust of the fluid on the rod remains less than the antagonistic thrust of the fluid on the movable stop.

It is known in fact that the thrust which results from the application of a pressurized fluid to a part is proportional to the surface offered to the fluid by this part.

Thus, the jack can take three stable positions by being controlled by a single pressurized fluid.

In other words, it is possible to control a jack according to the invention to make it hang, as desired, one of its three stable positions by injecting a fluid at appropriate points on the jack without modifying the pressure to which this fluid is subjected.

It is an all or nothing control, that is to say in which the pressure of the fluid introduced at a point of the jack is either zero or equal to a predetermined value.

In a preferred embodiment of the invention, there are on the outer wall of the chassis, at the height of the sliding pads, fixed stops against which the end pads of the stop member bear, the fixed stops being preferably adjustable in thickness.

In this way, the stroke of the guide member is limited on one side or the other of the chassis.

In a preferred embodiment of the invention, the sliding pads are articulated around horizontal axes at the end of the guide member which supports them.

In a preferred embodiment of the invention, two hydraulic cylinders are arranged in parallel one above the other to support the same pair of sliding pads.

In this case, it is advantageous to provide a vertically sliding connection between the pads and the rod of one of the two jacks, so as to allow the pads to tilt relative to the chassis.

• la figure 1 est une vue schématique d'un appareil selon un mode de réalisation de l'invention réalisant une tranchée dans le sol,
• la figure 2 est une vue analogue à la figure 1,
• la figure 3 est une vue en coupe de la partie supérieure du châssis représenté sur les figures 1 et 2.

In order to better understand the invention, we will now describe an embodiment given by way of non-limiting example of the scope of the invention with reference to the accompanying drawing in which:

• FIG. 1 is a schematic view of an apparatus according to an embodiment of the invention making a trench in the ground,
• FIG. 2 is a view similar to FIG. 1,
• FIG. 3 is a sectional view of the upper part of the chassis shown in FIGS. 1 and 2.

FIGS. 1 and 2 represent, seen from the side, an apparatus according to the invention which makes a trench 1 in a terrain 2.

The apparatus comprises a chassis 3, provided at its lower part with a pair of milling drums 4 (only one of which is visible in side view) which are rotated around axes 5 in opposite directions.

According to the invention, the upper part of the chassis 3 a is provided with a guide member 6.

In the embodiment shown, two pads 7 and 8 are each secured to one end of the guide member 6, so as to facilitate movement down or up of the chassis 3.

According to the invention, the spacing between the two pads 7 and 8 is kept constant and substantially equal to the thickness of the trench 1 dug by the milling drums.

In Figures 1 and 2, it is clear that, whatever the position of the guide member 6 with respect to the upper part 3a of the frame, the apparatus of the invention is constantly guided inside the trench 1.

Indeed, on the one hand the pads 7 and 8, the spacing of which is constant, remain in contact with the walls of the trench, and on the other hand the lower part of the chassis which supports the milling drums 4 remains centered relative to in the trench.

In Figure 1, the trench 1 has good verticality.

In this case, the guide member 6 is placed centrally, the upper portion 3a of the frame being thus equidistant from the two walls of the trench 1.

Thus, the device can continue its downward progression in the vertical direction.

On the other hand, in FIG. 2, it can be seen that the trench 1 is slightly moved away from the initially planned tracing which is shown in broken lines 9.

To reduce this deviation from the trench, the guide member 6 has been placed in a position offset to the right with respect to the chassis, which causes the chassis 3 to tilt slightly relative to the trench and a positioning of the milling drums. 4 suitable for bringing the appliance back to the vicinity of route 9.

We also see in this figure how hinge pins 10 connect the pads 7 and 8 to the central part of the guide member 6.

Shown in Figure 3 is a closer view in section of the upper part 3a of the chassis in which it is seen that the central portion of the guide member 6 is constituted by two identical cylinders arranged parallel one above the other.

In accordance with a preferred embodiment of the invention, each jack comprises a hollow cylindrical body 11 inside which slides a piston rod 12, each end of which is connected at 10 to a shoe 7, 8.

It is noted that the articulation 10 of the lower jack is also vertically sliding, which makes it possible to tilt the pads 7 and 8 as in the case of FIG. 2.

The piston rod 12 rests on two bearings 13, each disposed at one of the ends of the body of the jack 11, and whose internal sections 13a constitute bearing surfaces.

An annular flange 14, integral with the piston rod 12, seals between two annular chambers 15 and 16 located on either side of said flange 14, between the body of the jack 11 and the piston rod 12.

To this end, the flange 14 has a seal 17 and each of the bearings 13 also has a seal 18.

According to the invention, each cylinder has a movable stop 19 which here has the shape of a cylinder section comprising a projecting annular part 19 a at one of its ends.

According to the invention, the movable stop 19 is free to slide axially around the piston rod 12.

Two seals 20, arranged in grooves provided for this purpose on the inner and outer walls of the movable stop 19, on the side of the protruding part 19 a , seal between the annular chamber 16 and another annular chamber 21 between the stop 19 and the flange 14.

In the position of the jacks shown in FIG. 3, the volume of the chamber 21 is reduced to its minimum.

The fluid is supplied to the actuator through three orifices 22, 23 and 24 opening respectively into the annular chambers 15, 21 and 16.

Conduits 25, 26, 27 are provided in the upper part 3 a of the chassis for conveying the fluid supplied by pipes not shown which descend from the surface of the ground and are connected to the upper part 3 a of the chassis.

Lines 25, 26 and 27 have extensions 28, 29 and 30 which interconnect the chambers corresponding 15, 21 and 16 of the two hydraulic cylinders to ensure simultaneous operation of the latter.

We will now explain the operation of the jacks which have just been described.

Firstly, if a pressurized fluid is introduced into the duct 26, the duct 25 not being under pressure, and the duct 27 being in an indeterminate state, the annular chamber 21 is filled, and consequently the movement to the left of the piston rod 12 which abuts against the bearing surface 13 a of the bearing 13 located on the left in the drawing.

Secondly, if a pressurized fluid is introduced into the conduits 25 and 27, the conduit 26 not being under pressure, the annular chambers 15 and 16 are filled, which creates two opposing thrusts, exerting the one on the piston rod 12 as represented by the arrow 31, the other on the movable stop 19 as represented by the arrows 32.

Given the fact that the surface presented by the flange 14 in the chamber 15 is less than that presented by the stop 19 in the chamber 16, the thrust 32 is slightly greater than the thrust 31.

As a result, the stop 19 comes to bear against the bearing 11 a of the cylinder body, and the piston rod 12 takes the position shown in FIG. 3.

Thirdly, if a pressurized fluid is introduced into the duct 25, the ducts 26 and 27 not being under pressure, the piston rod 12 and the stop 19 which comes comes to the right then lean against the bearing 13 a of the bearing 13 located on the right in the drawing.

It is understood that the control of the jack described above can be carried out by simply determining the conduit or conduits into which a fluid under pressure is introduced, without it being necessary to establish a pressure difference between two particular conduits.

As a result, such a jack does not require any particular adjustment during its use since the three stable positions which it can take result solely from the geometry of the mechanical parts of which it is made up.

In addition, such a cylinder accommodates particularly simple control means.

In FIG. 3, there is also shown in broken lines the location of fixed external stops 33 secured to the external wall of the upper part 3 a of the chassis, at the height of the sliding pads 7 and 8.

Thanks to these stops 33, it is possible to limit the departure of the guide member 6 from one side or the other of the chassis, without modifying the position.

It is understood that the embodiment which has just been described has no limiting character of the scope of the invention, and that it can receive any desirable modifications without departing from the scope of the invention.

Claims (9)

Apparatus for digging deep trenches in the ground comprising a chassis provided with milling drums at its lower part, characterized in that the upper part (3 a ) of the chassis (3) is provided with at least one guide (6) which comprises, in the direction parallel to the axes (5) of the milling drums (4), ends (7, 8) spaced apart by a constant distance substantially equal to the thickness of the trench (1), and may take during operation of the apparatus, a centered position in which the upper part (3a) of the frame is located substantially equidistant from the two ends (7,8) of the guide member (6), a position offset from one side of the chassis (3) in which the upper part (3 a ) of the chassis is brought closer to a predetermined distance from one (7) of the ends of the guide member (6), and a remote position on the other side of the chassis (3) in which the upper tie (3 a ) of the chassis is brought closer to a predetermined distance from the other end (8) of the guide member (6). Apparatus according to claim 1, characterized in that the guide member (6) has a sliding pad (7,8) at each of its ends. Apparatus according to any one of claims 1 and 2, characterized in that the guide member (6) consists of a hydraulic cylinder with three positions mounted on the upper part (3 a ) of the chassis, and whose rod piston (12) extends over the entire thickness of the chassis. Apparatus according to claim 3, characterized in that the actuator comprises an axially movable stop (19) which, when subjected to the thrust of a pressurized fluid, is positioned so as to limit the stroke of the piston rod (12) between a first end-of-travel position at one end of the jack and an intermediate position in abutment on the movable stop (19), and, when it is not subjected to any thrust of fluid, to move freely with the piston rod (12) to allow the latter to reach its second end position - at the other end of the cylinder. Apparatus according to claim 4, characterized in that the movable stop (19) is in the form of a cylinder section which is housed around the piston rod (12), on one side of a flange ( 14) secured to the piston rod (12). Apparatus according to claim 5, characterized in that the movable stop (19) has a cross section of the fluid under pressure greater than that presented by the annular flange (14) of the piston rod (12). Apparatus according to any one of Claims 1 to 6, characterized in that fixed stops (33) are fixed to the external wall of the upper part (3 a ) of the chassis, at the height of the sliding pads (7, 8). Apparatus according to any one of Claims 1 to 7, characterized in that each sliding shoe (7,8) is articulated around a horizontal axis (10) at the end of the guide member (6) who supports them. Apparatus according to any one of claims 1 to 8, characterized in that it comprises a plurality of guide members (6) arranged one below the other and supporting the same pair of sliding pads ( 7, 8).

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