Drum suitable for anchoring a cable on a frame

Abstract

The invention relates to a drum (1) suitable for anchoring a cable (3) on a frame (2), the drum (1) being suitable for being rotatably mounted about an axis of rotation (X) on the frame (2), the drum (1) having a lateral surface (S) about an axis (Y) parallel to the axis of rotation (X), the drum (1) being characterised in that the lateral surface (S) comprises a first portion having at least a first radius of curvature measured in a plane (P) perpendicular to the axis of rotation (X) strictly greater than at least one second radius of curvature of a second portion of the lateral surface measured in the plane (P), the drum (1) being suitable for allowing the cable (3) to travel by winding and / or unwinding the cable (3) about the lateral surface (S) along the first portion, by rotating the drum (1) about the axis of rotation (X) between a first abutment position and a second abutment position.

Description

[0001] Drum suitable for anchoring a cable to a chassis

[0002] TECHNICAL FIELD

[0003] The invention relates to a drum suitable for anchoring a cable to a chassis and an anchoring system comprising this drum. The invention also relates to a lifting device comprising such an anchoring system and a lifting machine comprising said anchoring system.

[0004] STATE OF THE ART

[0005] Container lifting and handling can be implemented using a gripping frame, commonly called a "spreader", connected via cables to a crane, typically a "Ship to Shore" (STS) crane, i.e. from the ship to the quay, for unloading containers from a ship or reloading containers onto a ship. Motors mounted on the crane allow the gripping frame to be raised or lowered via the cables. Hooking devices (commonly called "twist locks") are also attached to the gripping frame. Opening - or closing - the hooking devices allows a container to be secured - or released. To enable their opening or closing, the hooking devices are commonly powered by a hydraulic unit most often arranged on the gripping frame.The hydraulic unit may further be adapted to force the extension or contraction of the gripping frame in use, so as to adapt said gripping frame for handling containers of different sizes. The hydraulic unit is advantageously supplied with energy from the crane via a cable: a first end of the cable is wound around a reel mounted on the crane and a second end of the cable is connected to the gripping frame, advantageously via a chassis (commonly called a "head block") under which said gripping frame is mounted. Alternatively, the hooking members are entirely electric, and their power supply from the crane is also via such a cable.The cable may also include a data bus, for example a CAN bus (according to the English acronym “Controller Area Network”), responsible for transmitting locking or unlocking information to the hooking devices as well as any other information necessary for controlling the crane (weighing, lighting, etc.).

[0006] In order to avoid damaging the cable, the unwinding and winding of the cable around the reel must keep the cable taut during all operations of lifting, unloading, loading, etc., of the containers. The unwinding and winding of the cable around the reel, so as to follow the movements of the gripping frame, are most often managed automatically by servo-control of the reel according to a theoretical model which calculates the torque to be applied to the reel according to the operating phase and the position of the crane on its travel.

[0007] However, since the movement of the gripping frame is often managed manually by the crane operator, some movements of the gripping frame cannot be immediately compensated for by the reel. This is particularly true in the event of sudden movements of the gripping frame when the frame is subjected to shocks, for example if the container misses the wedge and hits the container carrier's slides.

[0008] A cable anchoring system is therefore mounted on the chassis under which the gripping frame is mounted. This anchoring system may comprise a cylindrical drum advantageously mounted to rotate relative to the chassis by means of bearings, for example ball bearings. Under the effect of the tension of the cable, for example in the event of sudden movement of the gripping frame, said drum is rotated about its axis of rotation. The rotational movement of the drum causes the cable to be wound and / or unwound around said drum, thus providing a certain amount of clearance for the cable.

[0009] The anchoring system may further comprise shock absorbers, for example hydraulic, metallic or elastic shock absorbers (tensioners) and / or a compression spring adapted to dampen the movement of the cable: in particular, when the reel pulls on the cable, the compression spring provides a return force and absorbs the shock.

[0010] However, current anchoring systems, whose footprint is limited by the size of the frame on which they are housed, do not allow sufficient cable travel, particularly in the event of impacts. In fact, the travel offered to the cable by the anchoring system is typically around 40 mm in the direction of cable unwinding when the reel pulls on the cable and 40 mm in the direction of cable winding when the reel releases the tension on the cable. This results in rapid wear of the cable, which requires frequent and costly maintenance operations.

[0011] BRIEF DESCRIPTION OF THE INVENTION

[0012] An aim of the invention is to design a drum suitable for anchoring a cable on a chassis offering a large clearance for said cable while having limited space requirements.

[0013] To this end, the invention proposes a drum suitable for anchoring a cable on a chassis, said drum being suitable for being rotatably mounted about an axis of rotation on said chassis, the drum having a lateral surface about an axis parallel to the axis of rotation, the drum being characterized in that the lateral surface comprises a first portion having at least a first radius of curvature measured in a plane perpendicular to the axis of rotation (hereinafter referred to as "plane" for the sake of brevity) strictly greater than at least a second radius of curvature of a second portion of the lateral surface measured in said plane, the drum being suitable for allowing movement of the cable by winding and / or unwinding of said cable around the lateral surface along the first portion, by rotation of said drum about the axis of rotation between a first and a second stop position.

[0014] The drum advantageously has a lateral surface with a variable radius of curvature, the portion of large radius of curvature of said drum being limited to the portion useful for the movement of the cable by winding and / or unwinding the cable along said portion. The drum thus offers a large movement to the cable while having a restricted size allowing it to be housed on small frames.

[0015] According to other optional drum characteristics taken alone or in combination where technically possible:

[0016] - the axis of rotation intersects the plane at a point of intersection located at a distance from the center of a circle tangent to the first portion between 0% and 10% of the value of a radius of the circle, the radius of the circle being equal to the first radius of curvature of the first portion, the first portion being centered around the point of intersection;

[0017] - the first portion includes the point of maximum radius of curvature of the lateral surface measured in the plane;

[0018] - the lateral surface has, in the plane, an ovoid shape and the first portion of the lateral surface is included in the part of the ovoid opposite the portion of said ovoid with the smallest radius of curvature;

[0019] - the lateral surface has, in the plane, the shape of an ellipse, and the first portion of the lateral surface is included in one of the two arcs of the ellipse delimited by the major axis of said ellipse;

[0020] - the point of intersection between the plane and the axis of rotation is located on the semi-minor axis of the ellipse opposite the first portion of the lateral surface relative to the center of the ellipse;

[0021] - the length of the first portion of the lateral surface measured in the plane is greater than 300 mm, preferably greater than 600 mm.

[0022] The invention also relates to a system for anchoring a cable comprising a chassis, a drum as previously described mounted to rotate on the chassis around the axis of rotation, and at least one spring for absorbing the forces generated by the movement of the cable between the first and second stop positions arranged between the drum and the chassis.

[0023] According to other optional features of the cable anchoring system taken alone or in combination where technically possible:

[0024] - the at least one force-absorbing spring is a torsion spring or a set of two torsion springs assembled in series;

[0025] - each torsion spring comprises a first prism with a hollow metal square base, a second prism with a hollow metal square base housed inside the first prism with an angular offset relative to the first prism, and four elastomer cylinders arranged between the first prism and the second prism, in the corners of the first prism;

[0026] - the cable anchoring system comprises two torsion springs in series, the second square-based prism of the first torsion spring being connected to the second square-based prism of the second torsion spring;

[0027] - the force absorption spring is arranged along the axis of rotation so as to allow rotation of the drum around the axis of rotation relative to the chassis between the first and second stop positions without a rolling bearing or bushing;

[0028] - the first and second stop positions are angularly offset relative to the axis of rotation by an angle between 0° and 60°, preferably between 0° and 90°.

[0029] The invention also extends to a lifting device comprising:

[0030] - a gripping frame comprising at least one member for hooking a load to be lifted,

[0031] - an anchoring system as previously described comprising a chassis and a drum as previously described, the chassis being fixed to the gripping frame and the drum being fixed to the chassis,

[0032] - a reel suitable for attachment to a lifting device,

[0033] - a cable, a first end of the cable being anchored to the drum of the anchoring system by fixed winding of at least two turns around the lateral surface of the drum and a second end of the cable being wound around the reel.

[0034] According to other optional characteristics of the lifting device taken alone or in combination where technically possible:

[0035] - the lateral surface has a minimum radius of curvature in the plane strictly greater than the static radius of curvature of damage of the cable;

[0036] - the reel is an electronically regulated reel and the length of the first portion of the drum measured in the plane is equal to twice the product of a maximum speed of the gripping frame by a reaction time of a regulation loop of said reel.

[0037] Finally, the invention extends to a lifting machine, such as a crane, a gantry or a forklift, comprising a lifting device as previously described.

[0038] BRIEF DESCRIPTION OF THE FIGURES

[0039] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:

[0040] - Figure 1A, Figure 1B and Figure 1C illustrate an example of application of a cable anchoring system according to the invention in which said system is fixed to a gripping frame itself mounted on a crane;

[0041] - Figure 2A and Figure 2B represent particular embodiments of the drum according to the invention in which the lateral surface of said drum has respectively, in a plane perpendicular to the axis of rotation of said drum, ovoid and elliptical shapes;

[0042] - Figure 3 represents a particular embodiment of the cable anchoring system according to the invention in which the lateral surface of the drum has an elliptical shape and an axis of rotation of the drum relative to the chassis at the center of the ellipse: the middle of Figure 3 represents the neutral position of the drum, Figure 3 at the bottom represents the case of the application by the cable of a subtraction on the drum causing the rotation of said drum in the direction of winding of the cable, Figure 3 at the top represents the case of the application by the cable of an overtraction on the drum causing the rotation of said drum in the direction of unwinding of the cable

[0043] - Figure 4 represents a particular embodiment of the cable anchoring system according to the invention in which the lateral surface of the drum has an elliptical shape and an axis of rotation of the drum relative to the chassis offset from the center of the ellipse: the middle of Figure 4 represents the neutral position of the drum, Figure 4 at the top represents the case of the application by the cable of a subtraction on the drum causing the rotation of said drum in the direction of winding of the cable, Figure 4 at the bottom represents the case of the application by the cable of an overtraction on the drum causing the rotation of said drum in the direction of unwinding of the cable;

[0044] - Figure 5 illustrates the problem of the “whiplash” effect in the case of a cable anchoring system comprising a circular drum with an axis of rotation of the drum relative to the frame offset from the center of the circle;

[0045] - Figure 6 illustrates an embodiment of the cable anchoring system in which said system comprises a drum having an elliptical shape and an axis of rotation offset from the center of the ellipse as well as a compression spring adapted to dampen a movement of the cable by winding and / or unwinding the cable around a portion of the ellipse;

[0046] - figure 7 represents a particular embodiment of a torsion spring;

[0047] - Figure 8A and Figure 8B represent a particular embodiment of the anchoring system of the invention in which said system comprises a drum having an elliptical shape and an axis of rotation offset from the center of the ellipse as well as four torsion springs adapted to dampen a movement of the cable by winding and / or unwinding the cable around a portion of the ellipse and arranged along the axis of rotation of the drum so as to allow rotation of said drum relative to the chassis.

[0048] For readability reasons, the drawings are not necessarily drawn to scale.

[0049] DETAILED DESCRIPTION OF EMBODIMENTS

[0050] The invention relates to a drum adapted to be mounted on a chassis and to anchor a cable on said chassis.

[0051] With reference to Figures 1A, 1B and 1C, the chassis 2 is preferably a chassis adapted to be mounted on a gripping frame 4, said gripping frame 4 comprising one or more hooking members 5, said hooking members being adapted for gripping a load. The hooking members 5 of the gripping frame 4 may comprise, for example, four rotating locks adapted for gripping a container.When in use, the gripping frame 4 is connected to a lifting machine 6, for example a crane, by means 7 for lifting said gripping frame 4, said lifting means 7 being adapted to allow the movement of the gripping frame 4 relative to the lifting machine 6, typically the raising or lowering of said gripping frame 4, said movement being able to be controlled remotely by an operator, for example a crane operator positioned in the control cabin or in a control room from where he controls several cranes alternately. Alternatively, said movement can be managed completely automatically without the intervention of said operator. The lifting means 7 of the gripping frame 4 may comprise ropes and one or more motors mounted on the lifting machine 6.

[0052] According to an embodiment not shown in Figures 1A, 1B and 1C, a second gripping frame can be connected to the lifting machine 6 by means for lifting said second gripping frame, said lifting machine 6 further comprising an intermediate platform. Such a configuration is particularly advantageous when the lifting machine is an STS crane: the gripping frame 4 is used to move a container between the ship and the platform while the second gripping frame is used to move said container between the platform and the quay.

[0053] The cable 3 comprises one or more conductive links for the transfer of power and / or data. Each conductive link may be in the form of an electrically conductive wire, an optical fiber, or any other suitable form. Preferably, the cable comprises at least one conductive power supply link and one conductive control link for the attachment members 5 of the gripping frame 4. When the drum 1 is in use, that is to say when the drum 1 is mounted on the chassis 2, the chassis 2 mounted on a gripping frame 4 and the gripping frame 4 connected to a lifting machine 6, a first end of the cable is anchored to the chassis 2 via the drum 1 and a second end of the cable 3 is wound around a reel mounted on the lifting machine 6.More specifically, the drum according to the invention comprises a lateral surface (S) located around an axis (Y), so that when the drum 1 is in use, the first end of the cable 3 is wound around said lateral surface (S).

[0054] The reel mounted on the lifting equipment is typically an electronically regulated reel comprising a motor that winds or unwinds the cable so as to keep the cable taut regardless of the operating phase of the gripping frame (for example, during ascent, descent, start-up or stop phases). A control unit calculates a torque setpoint to be applied depending on said operating phase. The torque value must be high enough to keep the cable taut without damaging it. The torque setpoint is sent to a frequency converter which translates said torque setpoint into current to be imposed on the motor. A variation in the torque setpoint, for example when the position of the gripping frame changes or the operating phase changes, causes a variation in the motor current.Such a control loop has a non-zero reaction time which is the sum of at least one reaction time linked to the electronics and one reaction time linked to the transformation of the setpoint into current. The reaction time linked to the electronics is estimated to be of the order of 75 ms. This reaction time does not allow the reel to respond quickly enough in certain situations, for example during sudden movements of the gripping frame, for example in the event of shocks or gusts of wind, thus generating tensions in the cable.

[0055] The drum 1 is therefore adapted to be rotatably mounted on the chassis 2 around an axis of rotation (X) parallel to the axis (Y), so that when the drum 1 is in use, the drum 1 can be freely rotated around the axis of rotation (X) under the effect of a tension in the cable 3 not immediately compensated by the reel, thus allowing movement of the cable 3 by winding and / or unwinding said cable around the lateral surface (S) along a portion of the lateral surface (S).

[0056] More specifically, the drum, in a position described as neutral, may be subjected to a tensile force from the cable due to the torque imposed on said cable by the reel, making it possible to keep said cable taut. Mechanical tension of the cable is understood as a variation in the traction applied by the cable to the drum compared to the traction applied to said drum in the neutral position. This may be an under-traction (configuration corresponding to a slack cable) or an over-traction (configuration in which the reel pulls on the cable with a traction higher than the theoretical resultant of the setpoint). Such mechanical tension will cause a rotational movement of the drum around the axis of rotation (X) compared to this neutral position.In the case of under-traction, the rotational movement around the axis of rotation (X) will be in the winding direction to take up the slack in the cable until eventually reaching a first stop position. In the case of over-traction, the rotational movement around the axis of rotation (X) will be in the unwinding direction of the cable to free up the cable until eventually reaching a second stop position.

[0057] Preferably, the drum is arranged so that during use of said drum, a first part of the first end of the cable remains wound around said surface (S) in all phases of use of the chassis, and a second part of said cable in the extension of the first part winds and / or unwinds along the portion of the lateral surface (S) due to the rotational movement of the drum around the axis of rotation (X) between the first and second stop positions. By way of example, the first part of the first end of the cable has a length at least equal to two complete turns of the surface (S), preferably greater than two and a half turns. The first part of the first end is advantageously long enough to cancel the tension of the cable at the end of said cable by a so-called capstan effect.In a manner known per se, the capstan effect establishes the relationship between a holding force applied to one end of a cable wound around the lateral surface of a pad, said pad possibly having a circular or non-circular section (for example an elliptical section) and a load force applied to an opposite end of said cable, which depends on the coefficient of friction of the cable on the lateral surface of the pad.

[0058] The drum 1 is characterized in that at least a first radius of curvature of a first portion 14 of the lateral surface (S) measured in a plane (P) perpendicular to the axis of rotation (X) is strictly greater than at least a second radius of curvature of a second portion of the lateral surface (S) measured in the same plane (P). The drum 1 is arranged so that, when it is mounted on a chassis 2, the winding and / or unwinding of said cable 3 around the lateral surface (S) due to the rotational movement of the drum 1 around the axis (X) between the first and second stop positions takes place along the first portion 14. In other words, the useful portion of said drum 1 is limited to the portion with a large radius of curvature.

[0059] For example, the lateral surface (S) in the plane (P) has the shape of an ovoid or an ellipse, or any other shape whose radius of curvature is not constant. Thus, the shape of the lateral surface (S) in the plane (P) is not a circle.

[0060] The lateral surface (S) may be smooth, so that it has a single tangent at any point in the plane (P). The lateral surface (S) therefore has a curved shape, corresponding exactly to the elliptical or ovoid shape described above. For this purpose, the lateral surface (S) may be formed by rolling a metal sheet. Alternatively and without departing from the scope of the invention, the lateral surface (S) may have multiple facets parallel to the axis of rotation of the drum, so that it has a polygonal shape in the plane (P) inscribed in the shape of non-constant radius of curvature, for example the shape of an ellipse or an ovoid. In other words, the lateral surface (S) generally has, in the plane (P), the shape of an ellipse or an ovoid. For example, the lateral surface (S) may be formed by bending a metal sheet, that is to say by successive foldings of the metal sheet.

[0061] The drum 1 is advantageously less bulky than a drum which would comprise a lateral surface (S) having in the plane (P) perpendicular to the axis of rotation (X) a circle shape (C1) tangent to the first portion 14 and of radius equal to the first radius of curvature (R1), while offering the cable a greater clearance along the first portion 14 than would be allowed by a drum 1 with the same first and second stop positions and comprising a lateral surface (S) whose shape in the plane (P) is a circle (C2) of radius equal to the second radius of curvature (R2) for the same lateral size on the chassis.

[0062] Figures 2A and 2B show examples of lateral surfaces (S) having the shapes of an ovoid and an ellipse respectively in the plane (P) (plane of Figures 2A and 2B) and compare said ovoid and ellipse to the circles (C1) and (C2).

[0063] Figure 3 represents the example of a drum 1 having an elliptical shape in the plane (P) in use on a chassis. In particular, Figure 3 represents in the center the configuration in which the drum 1 is in a neutral position. Figure 3 at the bottom represents the case of an under-traction of the cable 3: the drum 1 rotates from said neutral position in the direction of winding said cable 3 around the axis of rotation (X) to wind the slack cable. Figure 3 at the top represents the case of an over-traction of the cable 3: the drum 1 rotates from the neutral position in the direction of unwinding the cable 3 around the axis of rotation (X) to unwind the cable.

[0064] The ellipse has a large height requirement, but a very small width requirement. While the former is not particularly advantageous to reduce as it is not very restrictive, the latter must be limited so that the drum 1 can be mounted on a small chassis. The ellipse is therefore a particularly advantageous shape for the drum 1.

[0065] In the particular embodiment shown in Figure 3, the axis of rotation (X) intersects the plane (P) at the center of the ellipse.

[0066] Alternatively, the circle (C1) with a radius length equal to the first radius of curvature (R1) of the first portion 14 and tangent to said first portion 14 is considered (circle shown in Figure 2B, the first portion 14 is shown in bold). The center of said circle (01) is noted (01). Advantageously, the axis of rotation (X) intersects the plane (P) at a point of intersection (A) located at a distance from the center (01) of the circle (01) of between 0% and 10% of the value of the first radius of curvature. In other words, the axis of rotation (X) is placed near the center (01) of the circle (01) tangent to the first portion 14 with a radius equal to the first radius of curvature.

[0067] Preferably, the axis of rotation (X) intersects the plane (P) at the point of intersection (A) which is located at a distance from the center (01) of the circle (01) of between 0% and 5% of the value of the first radius of curvature, the first portion 14 being centered around the point of intersection (A). The fact that the first portion 14 is centered around the point of intersection (A) means that the point of intersection (A) is located on the radius of the circle (01) tangent to the first portion 14 which intersects the arc formed by the first portion 14 in its middle.

[0068] For example, the point (A) of intersection between the plane (P) and the axis of rotation (X) is located on the semi-minor axis of the ellipse opposite the first portion of the lateral surface (S) relative to the center of the ellipse.

[0069] Preferably again, the point of intersection (A) and the center (01) of the circle (01) tangent to the first portion 14 and of radius equal to the first radius of curvature are merged. By way of example, Figure 4 represents the particular case where the lateral surface (S) has an elliptical shape in the plane (P) and where the point of intersection (A) is merged with the center (01) of the circle (C1) tangent to the first portion and of radius equal to the first radius of curvature. Figure 4 in the middle corresponds to the configuration in which the drum is in a neutral position, Figure 4 at the top to the case of under-traction of the cable and Figure 4 at the bottom to the case of over-traction of the cable. The point of intersection (A) is in this case distinct from the center of the ellipse, and said center of the ellipse is generally located between the first portion and the point of intersection (A).The placement of the axis of rotation (X) near the center (01) of the circle (01) tangent to the first portion and of radius equal to the first radius of curvature or directly on said center (01) induces a distance of said axis of rotation (X) from the first portion compared to the case where it would be placed at the center of the ellipse.

[0070] For a given lateral surface (S), and a fixed angle between the first and second stop positions, an axis of rotation (X) further from the winding / unwinding portion offers the cable a greater clearance. In other words, the length I of the first portion 14 measured in the plane (P) is greater. Conversely, for a given clearance, the misalignment of the axis of rotation (X) by moving the first portion 14 away from it will require a smaller angle between the first and second stop positions. Moving the axis of rotation (X) away from the winding / unwinding portion is therefore particularly advantageous when the angle between the first stop position and the second stop position is constrained and cannot exceed a maximum value, for example due to springs damping the force of the cable 3 on the drum 1.

[0071] In the case of a lateral surface (S) having in the plane (P) a circle shape with a radius limited by the size of the frame on which the drum is to be arranged (for example said radius is equal to the second radius of curvature), the offset of the axis of rotation (X) relative to the center of the circle is known to those skilled in the art to allow, at a constrained angle between the first and second stop positions, to increase the length of travel offered to the cable. However, the passage from the neutral position to one or other of the stop positions, and vice versa, in this case causes a significant variation in the distance d' measured in the plane (P) between the cable and the straight line of the plane (P) parallel to said cable which intersects the axis of rotation (X), thus generating sudden rises of "waves" of the cable towards the reel, in other words the rapid propagation of a transverse displacement of the cable along the cable towards the reel (see figure 5).Although there are means of protecting the reel against such cable waves (e.g. guardrails), these means are not sufficient for frequent and / or large amplitude cable waves.The characteristic according to which the drum 1 is adapted for winding and / or unwinding a cable 3 along a first portion of a lateral surface (S) of said drum 1, said first portion 14 having a first radius of curvature greater than a second radius of curvature of a second portion of the lateral surface (S), combined with the positioning of the axis of rotation (X) close to the center (01) of the circle (C1) tangent to the first portion and of radius equal to the first radius of curvature makes it possible, for a constrained angle between the first and second stop positions, to offer a large clearance to the cable 3 while limiting this “whiplash” effect which can damage the cable 3 or eject the cable 3 from the reel when the wave of cable arrives on said reel.

[0072] The “whiplash” effect is all the better avoided as the point of intersection (A) is close to the center (01) of the circle (01) and the first portion 14 is centered around the point of intersection (A) (visible by comparison between figure 3 in which the axis of the cable 3 depends on the rotation of the drum 1 and figure 4 in which it does not).

[0073] According to a particular embodiment of the invention, the first portion 14 comprises the point of maximum radius of curvature of the lateral surface (S) measured in the plane (P) and / or, the average radius of curvature of the first portion 14 measured in the plane (P) is greater than or equal to the average radius of curvature measured in the same plane (P) of any portion of the lateral surface (S) of the same length as the first portion, the length of the portions being measured in said plane (P) and / or in which the first portion 14 is the flattest portion of the lateral surface (S) of length I measured in the plane (P).

[0074] Such a configuration advantageously makes it possible, for a given lateral surface (S) and an angle between the first stop position and the second fixed stop position, to obtain the greatest possible travel and to best avoid the “whiplash” effect previously described.

[0075] In the particular case where the lateral surface (S) in the plane (P) has an ovoid shape, the first portion 14 of the lateral surface (S) is preferably included in the part of the ovoid opposite the portion of the smallest radius of curvature of the ovoid. In other words, by comparing the ovoid shape to that of an egg, the portion of the smallest radius of curvature is the head of the egg, the first portion 14 is therefore preferably included in the foot of the egg (see portion in bold in Figure 2A). In this configuration, the ovoid has the advantage of being able to move the axis of rotation (X) away from the first portion 14 while keeping the point (A) of intersection of the axis of rotation (X) in the plane (P) inside the lateral surface (S).

[0076] In the particular case where the lateral surface (S) in the plane (P) has the shape of an ellipse, the first portion 14 of the lateral surface (S) is preferably included in one of the two arcs of the ellipse delimited by the major axis of said ellipse (see figures 2B, 3 and 4).

[0077] According to a particular embodiment of the invention, the length I of the first portion 14 of the lateral surface (S) measured in the plane (P) is greater than 300 mm, preferably greater than 600 mm, so as to offer a clearance of the cable 3 from the neutral position of at least 300 mm in the direction of winding of the cable and at least 300 mm in the direction of unwinding of the cable.

[0078] Indeed, the inventors consider that the ideal travel for the cable from the neutral position is the product of the maximum speed of the gripping frame by the reaction time of the feedback loop of the electronically regulated reel. The maximum linear speed given by the motors to the gripping frame is typically between 150 m / min or 2.5 m / s and 240 m / min or 4 m / s. The reaction time of the electronically regulated reel being, as indicated previously, of the order of 75 ms, the travel from the neutral position is therefore ideally 300 mm in both the direction of unwinding and winding of the cable onto the drum. A non-constant radius of curvature of the lateral surface (S) of the drum advantageously makes it possible to obtain such travel with an acceptable size of said drum on the chassis.

[0079] A length I of the first portion of the lateral surface measured in the plane (P) greater than 300 mm, with preferably a travel from the neutral position of 150 mm both in the direction of unwinding and winding of the cable on the drum may be sufficient when the maximum linear speed given by the motors to the gripping frame is lower, for slower cranes.

[0080] The invention also relates to a system for anchoring a cable 3, comprising a frame 2 and a drum 1 according to one of the embodiments previously described, rotatably mounted on the frame 2 around the axis of rotation (X). The anchoring system according to the invention further comprises at least one spring for absorbing the forces generated by the movement of the cable 3 between the first and second stop positions arranged between the drum 1 and the frame 2. Under the effect of the force applied to the spring due to the rotation of the drum 1 around the axis of rotation (X), said spring deforms. The arrangement of the spring between the drum and the frame is carried out so that the spring is in the middle of its deformation range when the drum is in the neutral position. This makes it possible to obtain an equivalent movement in the direction of winding the cable and in the direction of unwinding the cable.

[0081] Preferably, the first and second stop positions are angularly offset relative to the axis of rotation (X) by an angle between 0° and 60° and the middle of the deformation range of the at least one spring is located at 30°. According to a further preferred embodiment, the first and second stop positions are angularly offset relative to the axis of rotation (X) by an angle between 0° and 90° and the middle of the deformation range of the at least one spring is located at 45°.

[0082] According to one embodiment of the cable anchoring system shown in Figure 6, the at least one spring comprises a compression spring 8. In this embodiment, the cable anchoring system further comprises at least one bearing 9 arranged along the axis of rotation (X), said at least one bearing being adapted to allow rotation of the drum 1 around the axis (X) relative to the chassis 2 between the first and second stop positions. The bearing comprises for example a ball bearing, or bushings or any other rotational guide means. The compression spring is characterized by a resting length, a maximum compression length less than the resting length (length when the turns touch) and a stiffness constant. At a given stiffness constant, the angle between the first stop position and the second stop position is limited by the resting length of the spring on the one hand and the maximum compression length on the other hand.For example, a spring with a resting length of between 200mm and 250mm typically achieves an angle between the first stop position and the second stop position of between 15° and 20°. However, increasing the length of the spring means increasing the size of the anchoring system.

[0083] According to a preferred embodiment of the cable anchoring system, the at least one spring comprises a torsion spring.

[0084] In one variant, the anchoring system comprises a torsion spring arranged along the axis of rotation (X), a first part of said spring being rigidly connected to the chassis and a second part of said spring being rigidly connected to the drum, the second part being adapted to pivot relative to the first part so as to allow rotation of the drum around the axis of rotation (X). Thus arranged, the first and second stop positions may correspond to the extreme pivoting positions of the second part of the torsion spring relative to the first part. According to a preferred alternative, the first and second stop positions are between the extreme pivoting positions of the second part of the spring relative to the first part. Not rotating until reaching the extreme positions in use of the drum advantageously makes it possible not to unnecessarily reduce the service life of the torsion spring.

[0085] Such an arrangement of the torsion spring advantageously makes it possible not to use other means of rotating the drum relative to the chassis such as rolling bearings or bushings. Indeed, said rolling bearings or bushings are not suitable for the conditions of use of the anchoring system mounted on a gripping frame (permanent work on a limited rotation angle without ever making complete turns, numerous vibrations) and wear quickly, limiting the service life of the anchoring system. On the contrary, torsion springs, conventionally used in vibratory pads, are perfectly suited to such conditions of use. In addition, the use of torsion springs arranged along the axis (X) makes it possible to reduce the size of the anchoring system, in particular compared to the configuration in which the at least one spring comprises a compression spring.

[0086] In a further preferred variant, the cable anchoring system comprises at least two torsion springs mounted in series and arranged along the axis of rotation (X), a first part of a first spring being mounted on the frame, a first part of a second spring being mounted on the drum, and a second part of the first spring being rigidly connected to a second part of the second spring.

[0087] For a given lateral surface (S), the arrangement of two torsion springs in series advantageously makes it possible to double the angle between the first and second stop positions relative to the axis of rotation (X) and therefore to increase the length I of the first portion measured in the plane (P). In other words, this makes it possible to increase the travel offered to the cable. Thus, if the angle between the first and second stop positions relative to the axis of rotation (X) with a torsion spring is between 0° and 30°, placing two torsion springs in series advantageously makes it possible to increase the angle between the first and second stop positions to an angle between 0° and 60°. Such a travel angle between the first and second stop positions is not reasonably achievable with a compression spring.

[0088] A clearance angle between the first stop position and the second stop position of between 0° and 60° makes it possible to scan a first portion of length of between 0 and approximately 630 mm measured in the plane (P) when the first radius of curvature of the first portion of the lateral surface (S) measures 575 mm, the diameter of the cable 50 mm and the distance d' is advantageously equal to the first radius of curvature of said first portion of the lateral surface (S). Indeed, the arc length of the first portion to the neutral fiber of the cable I can be calculated as follows:

[0089] 2 x (575 + 25) x 7T x 60 l = - = 628.32 mm = 630 mm

[0090] 360

[0091] By way of example, with reference to Figure 7, each torsion spring 10 may comprise a first prism 11 with a hollow metal square base, a second prism 12 with a hollow metal square base housed inside the first prism 11 with an angular offset relative to the first prism 11, and four elastomer cylinders 13 arranged between the first prism 11 and the second prism 12, in the corners of the first prism. In this case, the first prism 11 may be rigidly connected to the frame - reciprocally to the drum - and the second prism 12 to the drum - reciprocally to the frame. In the particular configuration in which two torsion springs are mounted in series, the second internal prism 12 of the first torsion spring may be connected to the second internal prism 12 of the second torsion spring, for example by an intermediate shaft.The first external prisms 11 of the first and second torsion springs can be connected to the drum and the chassis by external jumpers.

[0092] Still if the angle between the first and second stop position relative to the axis of rotation (X) with a torsion spring is between 0° and 30°, the series connection of three torsion springs advantageously makes it possible to bring the angle between the first and second stop position to an angle between 0° and 90°.

[0093] In addition to the embodiments of the cable anchoring system previously described, the at least one spring may comprise two springs mounted in parallel, a first part of the first and second springs being connected to the frame and a second part of the first and second springs being connected to the drum, each of the first and second springs being able to be understood as a single spring or as at least two springs mounted in series. For the same angle of rotation of the drum around the axis (X), the parallel mounting advantageously makes it possible to double the force of the springs. In addition, the parallel mounting makes it possible to distribute the forces taken up on the frame on either side of the drum and thus to avoid shear forces on the springs.

[0094] By way of example, Figures 8A and 8B show the particular configuration according to which the at least one spring comprises a first set of springs consisting of a first torsion spring 10a connected in series with a second torsion spring 10b and a second set consisting of a third torsion spring 10c connected in series with a fourth torsion spring 10d, the first set and the second set of springs being connected in parallel with each other. Furthermore, the four springs are arranged along the axis of rotation (X).

[0095] The invention also relates to a lifting device comprising:

[0096] - a gripping frame 4,

[0097] - an anchoring system comprising a chassis 2 and a drum 1 as previously described, the chassis 2 being fixed to the gripping frame 4 and the drum 1 to the chassis 2,

[0098] - a reel suitable for attachment to the lifting equipment,

[0099] - a cable 3, a first end of the cable 3 being anchored to the drum 1 of the anchoring system by fixed winding of at least two turns around the lateral surface (S) of the drum 1 and a second end of the cable 3 being wound around the reel.

[0100] The static damage curvature radius of the cable 3 is defined as the minimum winding curvature radius of the cable 3 recommended by the manufacturer of the cable 3 to avoid damage, loss of performance and / or a reduction in the service life of said cable 3. Storing the cable 3 wound with a curvature radius smaller than the static damage curvature radius entails a risk of generating stresses on the conductors included in said cable 3, by compression of the conductors, for which the resistance of the conductors has not been tested by the manufacturer and thus of altering the internal geometry of the cable 3. The static damage curvature radius of the cable 3 may be of the order of six times the diameter of the cable 3.The dynamic damage curvature radius of the cable 3 is defined as the minimum curvature radius recommended by the manufacturer according to which the cable 3 can be bent and unbent repeatedly during use without damaging it, reducing its performance and / or its service life. Indeed, if the cable 3 is bent repeatedly according to a curvature radius smaller than the dynamic damage curvature radius, there is a risk of generating friction between insulators or between strands of the same conductor and mechanical tensions on certain strands or conductors while other strands or conductors are under tension. Such an imbalance of forces can cause the strands to break. The breakage of the strands can itself lead to piercing of the insulating sheaths or destruction of said sheaths by heating.The breakage of the strands and the damage to the sheaths can result in short-circuit problems and / or the stopping of the transmission of signals or power carried by the damaged cables. The dynamic damage curvature radius is strictly greater than the static damage curvature radius of the cable 3. According to a particular embodiment of the lifting device, the minimum curvature radius of the lateral surface (S) of the drum measured in the plane (P) is greater than the static damage curvature radius of the cable 3 and less than the dynamic damage curvature radius of said cable. Indeed, since the portion of the lateral surface (S) with the minimum curvature radius is never unwound, such an embodiment advantageously makes it possible to limit the size of the drum as much as possible without damaging the cable. For example, the minimum curvature radius of the lateral surface (S) is of the order of 330 mm.Such a value of the minimum bending radius advantageously allows the winding of cables with a diameter between 35 mm and 55 mm, whose static damage bending radius is less than 330 mm.

[0101] According to a particular embodiment of the lifting device, the reel is an electronically regulated reel and the length I of the first portion of the drum measured in the plane (P) is equal to the product of the maximum speed of the gripping frame by the reaction time of the regulation loop of said reel.

[0102] Finally, the invention relates to a lifting machine 6 comprising a lifting device as previously described. According to a particular embodiment of the invention, the lifting machine is a crane, a gantry or a forklift. The lifting machine 6 is for example a crane used for loading or unloading containers on a container ship.

[0103] According to a particular embodiment of the lifting machine 6, said lifting machine 6 comprises, in addition to the lifting device as previously described, a second gripping frame and an intermediate platform. For example, the lifting machine 6 is an STS crane and the gripping frame 4 of the lifting device 6 is used to move a container between the ship and the intermediate platform while the second gripping frame is used to move said container between the platform and the quay.

[0104] In a particular embodiment of the lifting machine 6 with two gripping frames, the second gripping frame is included in a second lifting device, said second lifting device being able to be produced according to any one of the lifting device embodiments previously described.

[0105] Alternatively, the lifting device does not include a second reel and a second cable anchored to the second gripping frame from the second reel.

Claims

CLAIMS 1. Drum (1) adapted for anchoring a cable (3) on a chassis (2), said drum (1) being adapted to be rotatably mounted about an axis of rotation (X) on said chassis (2), the drum (1) having a lateral surface (S) about an axis (Y) parallel to the axis of rotation (X), the drum (1) being characterized in that the lateral surface (S) comprises a first portion (14) having at least a first radius of curvature measured in a plane (P) perpendicular to the axis of rotation (X) strictly greater than at least a second radius of curvature of a second portion of the lateral surface measured in said plane (P), the drum (1) being adapted to allow movement of the cable (3) by winding and / or unwinding of said cable (3) around the lateral surface (S) along the first portion (14), by rotation of said drum (1) about the axis of rotation (X) between a first and a second stop position.

2. Drum (1) according to the preceding claim, wherein the axis of rotation (X) intersects the plane (P) at a point of intersection (A) located at a distance from the center (01) of a circle (C1) tangent to said first portion (14) of between 0% and 10% of the value of a radius of the circle (C1), the radius of the circle (C1) being equal to the first radius of curvature (R1) of the first portion (14), the first portion (14) being centered around the point of intersection (A).

3. Drum (1) according to one of the preceding claims, wherein the first portion (14) comprises the point of maximum radius of curvature of the lateral surface (S) measured in the plane (P).

4. Drum (1) according to one of the preceding claims, in which the lateral surface (S) has, in the plane (P), an ovoid shape and in which the first portion (14) of the lateral surface (S) is included in the part of the ovoid opposite the portion of said ovoid with the smallest radius of curvature.

5. Drum (1) according to one of claims 1 to 3, in which the lateral surface (S) has, in the plane (P), an elliptical shape, and in which the first portion (14) of the lateral surface (S) is included in one of the two arcs of the ellipse delimited by the major axis of said ellipse.

6. Drum (1) according to claim 5 in combination with claim 2 wherein the point (A) of intersection between the plane (P) and the axis of rotation (X) is located on the semi-minor axis of the ellipse opposite the first portion (14) of the lateral surface (S) relative to the center of the ellipse.

7. Drum (1) according to one of the preceding claims in which the length (I) of the first portion (14) of the lateral surface (S) measured in the plane (P) is greater than 300 mm, preferably greater than 600 mm.

8. System for anchoring a cable (3), comprising a chassis (2), a drum (1) according to one of the preceding claims rotatably mounted on the chassis (2) around the axis of rotation (X), and at least one spring (8, 10) for absorbing the forces generated by the movement of the cable (3) between the first and second stop positions arranged between the drum (1) and the chassis (2).

9. Anchoring system for a cable (3) according to the preceding claim, in which the at least one force-absorbing spring (8, 10) is a torsion spring or a set of two torsion springs (10a, 10b) assembled in series.

10. Cable anchoring system (3) according to the preceding claim, in which each torsion spring (10) comprises a first prism with a hollow metallic square base. (II), a second hollow metal square-based prism (12) housed inside the first prism (11) with an angular offset relative to the first prism (11), and four elastomer cylinders (13) arranged between the first prism (11) and the second prism (12), in the corners of the first prism (11).

11. Anchoring system for a cable (3) according to the preceding claim, comprising two torsion springs (10a, 10b) in series, the second square-based prism (12) of the first torsion spring (10a) being connected to the second square-based prism (12) of the second torsion spring (10b).

12. Anchoring system for a cable (3) according to one of claims 8 to 11, in which the force absorption spring (10) is arranged along the axis of rotation (X) so as to allow rotation of the drum (1) around the axis of rotation (X) relative to the chassis (2) between the first and second stop position without rolling bearing or bushing.

13. Cable anchoring system (3) according to one of claims 8 to 12, the first and second stop positions of which are angularly offset relative to the axis of rotation (X) by an angle of between 0° and 60°, preferably between 0° and 90°.

14. Lifting device comprising: - a gripping frame (4) comprising at least one attachment member (5) for a load to be lifted, - an anchoring system according to one of claims 8 to 13 comprising a frame (2) and a drum (1) according to one of claims 1 to 7, the frame (2) being fixed to the frame of gripping (4) and the drum (1) being fixed on the chassis (2), - a reel suitable for attachment to a lifting device, - a cable (3), a first end of the cable (3) being anchored to the drum (1) of the anchoring system by fixed winding of at least two turns around the lateral surface (S) of the drum (1) and a second end of the cable (3) being wound around the reel.

15. Lifting device according to the preceding claim, in which the lateral surface (S) has a minimum radius of curvature in the plane (P) strictly greater than the static radius of curvature of damage to the cable (3).

16. Lifting device according to the preceding claim, in which the reel is an electronically regulated reel and in which the length (I) of the first portion (14) of the drum (1) measured in the plane (P) is equal to twice the product of a maximum speed of the gripping frame by a reaction time of a regulation loop of said reel.

17. Lifting machine (6), such as a crane, a gantry or a forklift, comprising a lifting device according to one of claims 14 to 16.

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