EP0397270A1

EP0397270A1 - Linear winch with multiple vices with programmed control for continuous movement of the pulling cable

Info

Publication number: EP0397270A1
Application number: EP90201165A
Authority: EP
Inventors: William Zucchi; Paolo Biagini
Original assignee: Riva Calzoni SpA
Current assignee: Riva Calzoni SpA
Priority date: 1989-05-12
Filing date: 1990-05-08
Publication date: 1990-11-14
Also published as: IT8920485A0; IT1229712B

Abstract

The linear winch (1) with multiple vices (5, 8, 11) with programmed control for continuous movement according to this invention comprises a frame (12), on which there are present two vices (5, 8) slidable along tracks (13) secured to the frame (12), equipped with respective independent actuators (7, 10) for translatory movement along the tracks (13), and one fixed vice (11), integral with the frame (12) and aligned with the foregoing vices (5, 8), which vices (5, 8, 11), both fixed and slidable, are equipped with jaws (14a, 14b, 14c) holding in one direction, aligned and orientated in the same direction, through which there may be passed a cylindrical element (2), such as a cable, pipe or bar, freely slidable in them in one direction and restrained in the opposite direction, loaded in the direction of restraint of the jaws of the vices, there being present, for each vice (5, 8, 11), relative actuators (16a, 16b, 16c) for disengaging the jaws (14a, 14b, 14c) from the cable, these actuators (16a, 16b, 16c) capable of being controlled in opening and closing manually and in automatic sequence associated with the relative sliding movements for the movable vices (5,8), the opening of a jaw of the movable vices being actuated only when at least a part of the load of the cylindrical element has been given up to the other jaw.

Description

The subject of the present invention is a linear winch with vices for cables, bars, pipes and the like, with automatic continuous movement.
For the installation of cylindrical elements, such as cables, pipes, tubes or bars, of considerable length, for example for marine applications, it is necessary to arrange for them to be lowered or pulled by means of associated devices, which assure movement of them but at the same time secure holding.
For example, in various applications it must be possible for the cables to be unreeled from drums or reels and reeled up again on them, and the cables must be subject to tension or released, either freely or with loads attached to them.
In applications of small size, with limited loads and in the presence of flexible cables, these operations can be carried out directly by reeling up and unreeling the cable itself on a drum set in rotation, but for large loads and applications of large dimensions, requiring metal cables and drums of large diameter, in view of the relative flexional stiffness of the cables, direct reeling up of the cable in tension on a drum could lead to unacceptable loadings or to excessive dimensions for the structure of the drum itself, even under the self-weight alone of the cable.
In such cases, and in many analogous situations, it is therefore necessary to carry out the operations of tensioning and releasing the cable by means of a suitable winch, to which the pull caused by the cable is entrusted, while the cable itself may be reeled up or unreeled on a suitable drum, or be variously used or transferred, substantially without any pull.
Furthermore, in those cases in which operations are carried out on bars or tubes, these cannot be reeled up in any manner, but must be handled in every case by keeping them straight.
For this purpose, linear winches are known, equipped with a vice which can grip on the cable or tube or bar, and with translatory actuators for the vice, moving parallel to the cable, in conjunction with a second, fixed vice; such winches, with reciprocating movement of the movable vice and coordinated openings and lockings of the vices, can pull in or release the cable by successive steps, of magnitude equal to the stroke of the actuators used.
In some circumstances, however, a pulsed movement is not desirable and therefore the problem arises of providing a linear winch for pulling and releasing a cable which shall assure a continuous movement, at constant velocity, guaranteeing moreover that in every phase of operation of the winch the cable shall be firmly held and cannot escape.
Furthermore, the devices having vices of known type provide for sliding of the jaws of the vices on the surface of the cable or bar, which on the one hand is a source of friction and on the other hand causes considerable wear of the jaws themselves, requiring their frequent replacement, as well as wearing out the cable itself.
There is therefore a need for a winch which shall work by reducing or eliminating entirely the friction and sliding on the element lifted, without however this leading to a reduction in the security and safety of the operations.
Said results are achieved by the present invention, which provides a linear winch with vices for continuous movement, which comprises a frame, on which there are present two vices slidable on tracks secured to the frame, equipped with respective independent actuators for for translatory movement along the tracks, and one fixed vice, integral with the frame and aligned with the aforementioned vices, which vices, both fixed and slidable, are equipped with jaws holding in one direction only, aligned and oriented in the same way, through which may be passed a cylindrical element, such as a cable, tube, pipe or bar, freely slidable in them in one direction and restrained in the opposite direction, and loaded in the direction of restraint of the jaws of the vices, there being present, for each vice, associated actuators for disengagement of the jaws from the cable, capable of being controlled in opening and closing both manually and in automatic sequence associated with the relevant sliding movements for the movable vices, the opening of a jaw of the movable vices being actuated only when at least a part of the load of the cylindrical element has been given up to the other jaw.
The actuators of the slidable vices are constituted of two side-by-side pairs of hydraulic jacks, having equal strokes and disposed symmetrically about the cable.
The internal pair of jacks possesses rods of shorter length, to the ends of which there is secured one vice, while the external pair possesses rods of greater length, carrying at the end the second vice.
As an alternative, the jacks possess rods of equal length and the internal pair of jacks has an anchor point set further back, in the direction of pull, with respect to the pair of jacks further out.
The jacks have feed velocities, in the direction of pull, smaller than the velocity of movement in the opposite direction.
The jacks possess equal and independent supply sources of hydraulic fluid.
The jacks are supplied from a hydraulic circuit comprising sensor means of the load carried by one pair of jacks, in the pulling phase and with the relevant jaws in the gripping position, the sensor means being adapted for governing release of the jaws of the other pair and the return movement of the associated jacks only when a predetermined value of load carried by the first pair of jacks is exceeded.
The jaws of the fired vice are normally open and can be manually actuated into the gripping position in every phase of the automatic pulling cycle of the jaws of the movable vices.
Further details will be found from the following description of an example of embodiment of the invention, with reference to the attached drawings, in which there are shown:

in Figure 1, a schematic general view of a pulling assembly for jacks with a reciprocating winch according to this invention;
in Figure 2, the reciprocating winch of Figure 1, seen in plan;
in Figure 3, the reciprocating winch of Figure 2, in lateral view;
in Figure 4, a section on the plane IV-IV of Figure 2;
in Figure 5, a section on the plane V-V of Figure 2;
in Figure 6, a section on the plane VI-VI of Figure 2;
in Figure 7, a hydraulic actuation diagram.

As Figure 1 shows, a unit for pulling and releasing cables according to this invention comprises a reciprocating winch 1, through which a cable 2 passes, which can be reeled up or unreeled in turns on a winding drum 3.
The winch 1 is hydraulically operated and can exert a pull on the cable, taking its weight and progressively pulling it in, feeding it to the drum 3, rotationally driven by the motor 4; with the reverse movement, the winch may, instead, unwind the cable, unreeling it from the drum 3, in all cases holding the load applied to the cable and caused by the self-weight of the cable itself and the weight of elements or equipment attached to it, without this load acting on the drum.
The winch 1 comprises a first movable vice 5 for gripping the cable, carried by the rods 6 of a pair of hydraulic jacks 7; a second movable vice 8 for gripping the cable, carried by the rods 9 of the pair of hydraulic jacks 10, and a fixed vice 11, firmly secured to the frame 12 of the winch.
As can be more readily seen from Figures 2 to 6, the movable vices 5 and 8 are slidable on tracks 13; each of these vices, and also the fixed vice 11, possesses a pair of movable jaws, referenced respectively 14a, 14b, 14c for the vices 5, 8, 11, and having wedge-shaped sides, adapted for gripping around the cable when it is subjected to tension in the direction of the arrow F of Figure 2, that is to say in the direction of unreeling from the drum 3, and thus preventing sliding of the cable with respect to the associated vice in this direction, whereas in the opposite direction the movement of the cable causes, by friction, disengagement of the vices from the cable, which can therefore slide freely.
Said jaws have replaceable slide guides, suitable for allowing easy maintenance, and can be opened at the top for the introduction of the cable; these jaws, in their general characteristics, are of a type known in the art, and their construction will therefore not be described in greater detail.
The jacks 7 and 10 have equal strokes and are disposed side-by-side, the pair of jacks 10 being accommodated between the two jacks 7, in this way limiting the overall length of the assembly.
Behind the fixed jack 11 there are present the guide rollers for the cable 15, which allow lateral deflection of said cable, without sliding, through the angle necessary for it to wind correctly onto the drum 3, as indicated in Figure 1 in dot-and-dash lines.
The jaws 14 (a, b, c) of the vices are equipped with hydraulic (oil) jacks 16 (a, b, c), by means of which the blocking and unblocking of the jaws from the cable can be directly actuated, without this taking place with sliding of the cable inside the jaws, thus reducing loading and wear.
The construction according to this invention enables pulling-in of the cable 2 to be achieved with continuous pull, that is to say without stops associated with the cyclical movement of the pulling devices.
In fact, starting from an initial position, in which the vice 5 is in its position of maximum advance 5′, as illustrated in Figure 2 in broken lines, at the start of the retraction movement of the vice the relevant jaws 14a engage by friction with the cable and grip onto it, thus initiating its pulling-in; at a predetermined distance from the end-of-stroke position of the vice 5, which is shown in full lines in Figure 2, the return movement of the vice 8 commences, which vice had previously reached its position of maximum advance 8a, shown in full lines in Figure 2.
This return movement causes the progressive engagement by friction of the jaws 14b with the cable 2, with transfer to these jaws, and therefore to the vice 8, of the associated load; when a certain percentage of the load has been transferred to the jaws 14b, the vice 5 reverses its motion and returns into the advanced position 5′ at a higher velocity than the pulling velocity, thereby becoming available for renewed engagement with the cable.
In analogous manner, at a predetermined distance from the end-of-stroke position of the vice 8, indicated in Figure 2 in broken lines and referenced 8b, the vice 5 commences a new pulling movement, progressively taking over the load of the cable, while the vice 8 is rapidly brought into the advanced portion 8a for the continuation of the cycle, which can be automatically repeated until complete pulling-in of the cable, or until a stop command.
In this manner, the movement of the cable 2 is continuous, without stops or variations in speed during the transition phases between the gripping of one jaw and the release of the other.
The fixed vice 11 is kept open and allows the cable to slide in it towards the drum, but can be manually blocked in case of need and constitutes a safety component, which therefore prevents return of the cable in case of anomalies also, for example if the movable vices or their associated jacks should fail.
In greater detail, with reference to the hydraulic diagram of Figure 7, the feed pressure Pt is supplied at the valve 17 and at the valves 18, 19 for piloting the respective jaws 14a, 14b, while their selector valves 20, 21 are at discharge.
In the conditions of Figure 7, the jacks 10 of the jaws 14b are in pulling movement, actuated by the feed pressure Pb; when the end plungers 10a of the pistons of the jacks 10 sealingly enter the respective cups 10b, the pilot pressure is fed to the valve 23, which, multiplied by the jacks 10, overcomes the opposed piloting derived from the feed Pb via the valve 30 and causes switching of said valve 23.
The valve 23 now causes closing of the one-way valve 24 and opening of the one-way valve 25, and pilots the valve 18, determining closing of the jaws 14a and movement of the jacks 7, which continues simultaneously with that of the jacks 10.
When the pressure in the feed line to the jacks 7, connected to the feed Pa, reaches a predetermined value, for example equal to one-half of Pb, to which the valve 26 is calibrated, this means that the jacks 7 are loaded with a part of the tension in the cable; the valve 26 snow opens the passage and pilots the valve 27 which, through the valve 19, causes opening of the jaws 14b and opens the one-way valve 28, while the valve 29 closes, permitting the return of the pistons of the jacks 10 while the jacks 7 hold the tension in the cable and complete their stroke.
Because it is arranged that the effective area of the pistons of the jacks 7 and 10 of the side corresponding to their piston rods is slightly smaller than the effective section of the pistons on the opposite side, the velocity of the pistons of the jacks 10 in the return stroke is greater than the velocity of the jacks 7 in the pulling stroke (and vice versa), so that the jacks 10 can be available for engaging again with the cable before the jacks 7 have completed their pulling stroke (and vice versa).
When the jacks 7 are near the end of their stroke, the end plungers 7a of the associated pistons enter sealingly into the cups 7b of the jacks 7, thus pressurizing the pilot line to the valve 27 to a pressure greater than the opposite pressure supplied by the valve 26. This causes the exchange cycle for the pull between the jaws 14a and the jaws 14b, described above, to be repeated, acting on the one-way valves 24 and 25, while the valve 30, calibrated in the same manner as the valve 26, permits releasing by-the jaws 14a only when at least one-half of the pull is held by the jaws 14b.
The feeds Pa and Pb are equal, but are supplied from two different pumps, operating simultaneously, to make the two circuits independent and prevent imbalance occurring between the circuits.
Finally, through the valve 31 it is possible, at any instant, to bring the jaws 14c into operation, which jaws are normally inactive and therefore are not subject to wear or the like, for the purpose of blocking the cable in case of emergency. Such a gripping intervention may be automatically actuated by appropriate detector means of known type, or may be manually actuated.
Releasing of the cable is carried out with the inverse sequence of the movements of the vices, under manual control, or automatically, in correspondence with each exchange between the vices alternately holding the cable, the disengagement of the respective jaws 14a, 14b by means of the jacks 16a - 16b; the jaws 14c are, in this operation also, kept continually open to allow the cable to pass through. The valves 32 and 33 are the same as the valves 26 and 30 already mentioned.
The linear winch according to this invention therefore enables the operations of pulling in and paying out a cable of large dimensions and/or subject to high loads to be carried out in a continuous procedure without shocks or jerks, but without the possibility of a situation of failure or uncontrolled sliding of the cable occurring, the cable itself being always held by at least one vice, with the jaws in the clamping condition.
Numerous variants can be introduced, without thereby departing from the scope of the invention in its general characteristics.

Claims

1. Linear winch comprising vices, with continuous movement, characterized by the fact that it comprises a frame, on which are present two vices slidable on tracks secured to said frame, the vices being equipped with respective independent actuators for translatory movement along said tracks, and one fixed vice, integral with the frame and aligned with the preceding ones, which vices, fixed and slidable, are equipped with jaws holding in one direction, aligned and orientated in the same way, by means of which a cylindrical element, such as a cable, tube, pipe or bar, may be allowed freely to slide in one direction and held in the opposite direction by acting in the direction of holding of the jaws of the vices, there being present, for each vice, relative actuators for disengagement of the jaws from the cable, capable of being operated in opening and closing and in automatic sequence associated with the relevant sliding movements for the movable vices, the opening of one jaw of the movable vices being actuated only when at least a part of the load of the cylindrical element has been given up to the other jaw.

2. Linear winch according to Claim 1, characterized by the fact that the actuators of the slidable vices are constituted of two pairs, disposed side-by-side, of hydraulic (oil) jacks, having equal strokes.

3. Linear winch according to Claim 2, characterized by the fact that the inner pair of jacks possesses rods of smaller length, to the ends of which one vice is attached, while the pair further out possesses rods of greater length, carrying at the end the second vice.

4. Linear winch according to Claim 2, characterized by the fact that the jacks possess rods of equal length, and the inner pair of jacks has an anchorage point set further back, in the direction of pull, with respect to the pair further out.

5. Linear winch according to Claim 2, characterized by the fact that the jacks have velocities of advance, in the direction of pulling, smaller than the velocities of movement in the opposite direction.

6. Linear winch according to Claims 2, 5, characterized by the fact that the jacks possess equal and independent sources of supply of hydraulic fluid.

7. Linear winch according to Claim 2, characterized by the fact that the jacks are supplied from a hydraulic circuit comprising sensor means of the load carried by a pair of jacks in the pulling phase and with the relative jaws in the gripping position, the sensor means being adapted for causing release of the jaws of the other pair and the return of the relevant jacks only when a predetermined value of load carried by the first pair has been exceeded.

8. Linear winch according to Claim 1, characterized by the fact that the jaws of the fixed vice are normally open and can be actuated into the gripping position in any phase of the automatic cycle of pulling by the jaws of the movable vices.