DESCRIPTION

[0001 ]The present invention relates to a hydrodynamic tool for the axial compression of tube connections.

[0002]For connecting tubes, e.g. metal, polymeric, composite, single-layer or multi-layer tubes for gas or water or steam, one end of the tube is irreversibly coupled to a connection device 100 (figures 15, 16), preferably made of metal, e.g. brass or steel, which connection device 100 can be connected to another tube, in turn. The connection device 100 comprises a plurality of connection ends 101 in mutual flow communication and comprising one or more irreversible coupling ends 102 with:

- a contrast portion 103 forming a contrast flange 104,

- a fastening portion 105 forming a frontal annular surface 106,

- a seat 107 for accommodating the tube end by inserting the tube end in axial direction 10 with respect to an axis 10 of the tube end and the coupling end 102,

in which an axial approaching translation of the fastening portion 105 and of the contrast portion 103 fastens and locks the tube end in the seat 107.

[0003]ln addition to the one or more irreversible coupling ends 102, the connection device 100 may comprise one or more further connection ends 101 , e.g. a threaded end or an end provided with a coupling nut.

[0004]ln order to perform the approaching translation of the fastening portion 105 and of the contrast portion 103 of the connection device 100, the use of a hydrodynamic compression tool 108 is known (figure 17), comprising:

- an electrohydraulic pump 109 with a pump body 1 10 forming a handle 1 1 1 for manually gripping the tool and an operating button 1 12 arranged on the handle 1 1 1 on an operating side 1 13 of the pump body 1 10,

- a compression head 1 14 with a head body 1 15 rigidly connected to the pump body 1 10, and a hydraulic actuator 1 16 supported by the head body 1 15 and operable by the electrohydraulic pump 109, in which a cylinder 1 17 of the hydraulic actuator can translate with respect to the head body 1 15 along an actuation axis 1 18 and a piston 1 19 of the hydraulic actuator is stationary with respect to the head body 1 15 and freely resting against a locking pin 120 integral with the head body 1 15 and which extends through the cylinder 1 17 outside the piston 1 19;

- a plurality of first jaw seats 121 formed in the head body 1 15 with orientations in different radial directions, at an angular pitch of 90°, with respect to the actuation axis 1 18, and a plurality of second jaw seats 122 formed in one end of the cylinder 1 17 with the same orientations as the first jaw seats 121 ;

- a first compression jaw 123 that which can be reversibly coupled to any of the first jaw seats 121 and a second compression jaw 124 which can be reversibly coupled to any of the second jaw seats 122, so as to vary the orientation of the compression jaws with respect to the operating side 1 13 of the pump body 1 10;

in which the first jaw 123 and the second jaw 124 each form a seat 125 which is laterally open to engage the contrast flange and/or the annular front surface of the connection device 100 by transversal insertion with respect to the compression axis 10, as well as a coupling portion for the coupling to the jaw seats 121 , 122 to be able to compress the connection device 100 along the compression axis 10 parallel to and spaced apart from the operating axis 1 18.

[0005]The known axial compression tool for tube connections has some disadvantages.

[0006]The clearance conditions around the tubes to be connected and the orientation of the tubes are very variable. Therefore, in order to allow a comfortable use of the compression tool, with an ergonomic working posture and with the possibility of grasping the tool correctly and pressing the actuating button with the index finger, it would be necessary to remove and reattach the jaws, in the more appropriately oriented jaw seats, many times during the execution of the work. To avoid this repeated and tedious movement of the jaws, users orient the tool as best as they can, gripping it incorrectly, and consequently they actuate the operating button with their thumb or by means of another finger other than the index finger resulting in precarious control. This increases the risk of compression errors in the connections, the risk of accidents and of fatigue or damage to health due to unhealthy posture, in particular of the user’s hand and arm.

[0007]Since the hydraulic actuator cannot be arranged coaxially with the axis of the connecting device to be compressed, the compression jaws are undesirably large in size because they must provide a high mechanical resistance to bending and shearing, due to the distance between the actuation axis of the hydraulic actuator and the axis of the connecting device along which the compression takes place. This results in excessive jaw weight and tool imbalance and/or excessive manufacturing costs of the jaws by stock removal machining from a solid semi-finished block.

[0008]The locking pin, which holds the piston stationary in relation to the head body, transmits the entire reaction force of the compression from the piston to the head body and inevitably has a heavy weight and large size. This and the positioning of the locking pin outside the piston leads to an additional unbalance of the tool and the need to increase the overall length of the cylinder by at least the diametrical size of the locking pin. [0009]The inevitable distance between the actuation axis of the hydraulic actuator and the axis of the connecting device along which the compression takes place, leads to relative displacements and unplanned bending at the ducts 127 and gaskets for the supply of hydraulic oil from the electrohydraulic pump to the hydraulic actuator which, in the tool of the prior art, lead to undesirable hydraulic oil leaks, gasket wear and/or the need to oversize the hydraulic ducts and the sealed interfaces.

[0010]Furthermore, in the tool of the prior art, the return of the cylinder from a position close to the jaws to a position away by the jaws is achieved by means of a return spring 128 inserted in a cavity of the cylinder and precompressed between the locking pin and a closing plate 129 fixed by means of a Seeger ring 130 to one end of the cylinder. The preload of the return spring pushes the locking plate permanently outwards from the cylinder and, if the Seeger ring is removed, the preload of the return spring catapults the locking plate dangerously outwards from the cylinder.

[001 1 jFinally, in order to allow the translation of the cylinder with respect to the head body despite the presence of the locking pin, in the tool of the prior art the locking pin is accommodated in two, diametrically opposite, elongated slots 131 formed in the cylinder itself and that, during the use of the tool also extend outside the head body with the risk of effects of milling on the edges of the head body and the slots and of falling foreign bodies inside the cylinder.

[0012] It is the object of the present invention to suggest an improved hydrodynamic tool for axially compressing tube connections with respect to the prior art.

[0013]lt is a particular object of the invention to suggest an hydrodynamic tool for the axial compression of tube connections having such features as to be able to engage the connection devices in any position they can be found without having to repeatedly detach and reattach the jaws because of this and to allow a comfortable use of the compression tool, with an ergonomic working posture and with the possibility of always grasping the tool in the correct manner and pressing the operating button with the correct finger.

[0014]lt is a further particular object of the invention to suggest a hydrodynamic tool for the axial compression of tube connections with such features as to reduce the weight, size and cost of replaceable jaws or replaceable inserts, as well as tool imbalances due to excessively heavy jaws.

[0015]lt is a further, particular object of the invention to suggest a hydrodynamic tool for the axial compression of tube connections with features to improve the positioning of the locking pin with respect to the piston in order to reduce the unbalance of the tool and the overall length of the cylinder. [0016]lt is a further particular object of the invention to suggest a hydrodynamic tool for the axial compression of connections of tubes with such features as to reduce unwanted hydrodynamic oil leaks, wear of gaskets and/or the need to oversize the hydrodynamic tubes and the sealing interfaces.

[0017]lt is a further particular object of the invention to suggest a hydrodynamic tool for the axial compression of tube connections with such features that, during maintenance operations, the preload of the return spring cannot inadvertently catapult the locking plate out of the cylinder.

[0018]lt is a further particular object of the invention to suggest a hydrodynamic tool for the axial compression of tube connections with such features as to reduce or eliminate milling effects between head body edges and the cylinder slots and to avoid the falling of foreign bodies into the cylinder.

[0019]At least some of the aforesaid objects are achieved by means of a hydrodynamic tool for the axial compression of connection devices for tubes according to claim 1. The dependent claims relate to advantageous embodiments.

[0020]According to an aspect of the present invention, a hydrodynamic tool for the axial compression of tube connections comprises:

- an electrohydraulic pump with a pump body forming a handle for manually gripping the tool and an operating button arranged on the handle on an operating side of the pump body,

- a compression head with a head body connected to the pump body, and a hydraulic actuator supported by the head body and which can be operated by the electrohydraulic pump, in which a cylinder of the hydraulic actuator can translate with respect to the head body along an actuation axis and a piston of the hydraulic actuator is locked so as to be unable to translate with respect to the head body along the actuation axis,

- a first compression jaw connected to the head body and radially protruding from the head body with respect to the actuation axis on a compression side of the head body, and a second compression jaw connected to the cylinder and protruding from the cylinder radially with respect to the actuation axis on the same compression side as the first compression jaw,

in which the first jaw and the second jaw each form a compression seat which is open towards said compression side to accommodate a connection device by means of transversal insertion with respect to a compression axis of the connection device and to perform a compression of the connection device along the compression axis which is parallel to and spaced apart from the actuation axis,

in which the head body and the cylinder can rotate together with respect to the pump body to allow an orientation of the compression side with respect to the operating side of the tool.

[0021]This allows a more comfortable use of the compression tool, with an ergonomic working posture and with the possibility of always grasping the tool in the correct manner and operating the operating button with the correct finger, without having to repeatedly remove and reattach the jaws.

[0022]These and other aspects and technical effects of the invention will be described in greater detail below with reference to some non-limiting embodiments, in which:

[0023]figure 1 is a perspective view of an axial compression tool with a linear-bar-shaped pump body according to an embodiment;

[0024]figure 2 is an exploded view of a detail of the tool in figure 1 , according to an embodiment,

[0025]figures 3 and 4 are section views of a detail of the axial compression tool in configuration with jaws mutually spaced apart (figure 3) and in configuration with jaws approached (figure 4), according to an embodiment,

[0026]figure 5 shows a detail of the axial compression tool with the jaws oriented about a first orientation axis with respect to the situation shown in Figure 1 ,

[0027]figure 6 shows a detail of the axial compression tool with the jaws oriented about a second orientation axis with respect to the situation shown in Figure 1 ,

[0028]figure 7 is a perspective view of a gun-shaped axial compression tool with a hydraulic pump according to an embodiment;

[0029]figure 8 shows a detail of the axial compression tool in figure 7 with the jaws oriented about an orientation axis with respect to the situation shown in figure 7,

[0030]figure 9 is a section view of a working head of the compression tool taken along the section plane IX-IX in figure 10;

[0031 jfigure 10 is a section view of the working head of the compression tool taken along section plane X-X in figure 9;

[0032]figure 1 1 is a section view of the working head of the compression tool taken along section plane XI-XI in figure 9;

[0033]figure 12 is an enlarged view of detail XII in figure 1 1 ;

[0034]figure 13 shows views of a locking pin of the compression tool according to an embodiment,

[0035]figure 14 is a view of a detail of the axial compression tool, in which a locking pin and the respective guide slots of a cylinder are oriented differently from the embodiment shown in figure 1 1 ,

[0036]figures 15 and 16 show examples of tube connection devices, [0037]figure 17 is a diagrammatic section view of a detail of an axial compression tool according to the prior art.

[0038]A hydrodynamic tool 1 for the axial compression of connection devices 100 for tubes, comprises:

- an electrohydraulic pump 2 with a pump body 3 forming a handle 4 for manually gripping the tool 1 and an operating button 5 for operating the pump 2 arranged on the handle 4 on an operating side 6 of the pump body 3,

- a compression head 7 with a head body 8 connected to the pump body 3 and a hydraulic actuator 9 supported by the head body 8 which can be operated by the electrohydraulic pump 3, in which a cylinder 1 1 of the hydraulic actuator 9 can translate with respect to the head body 8 along an actuation axis 12 and a piston 13 of the hydraulic actuator 9 is locked so as to be unable to translate with respect to the head body 8 along the actuation axis 12,

- a first compression jaw 14 connected to the head body 8 and radially protruding from the head body 8 with respect to the actuation axis 12 on a compression side 15 of the head body 8, and a second compression jaw 16 connected to the cylinder 1 1 and radially protruding from the cylinder 1 1 with respect to the actuation axis 12 on the same compression side 15 as the first compression jaw 14,

wherein the first jaw 14 and the second jaw 16 each form a compression seat 17 which is open towards said compression side 15 to accommodate a connection device 100 by transversal insertion with respect to a compression axis 10 of the connection device 100 and to be able to perform a compression of the connection device 100 along the compression axis 10 which is parallel to and spaced apart from the actuation axis 12,

in which the head body 8 and the cylinder 1 1 are connected so as to rotate together with respect to the pump body 3 to allow an orientation of the compression side 15 with respect to the operating side 6 of the tool 1.

[0039]This allows a more comfortable use of the compression tool 1 , with an ergonomic working posture and with the possibility of grasping the tool 1 always correctly and pressing the operating button 5 with the correct finger (e.g. the index finger in trigger position), without having to repeatedly remove, reposition and reattach the jaws.

[0040]According to an embodiment, the tool 1 comprises a rotatable column 18 connected to the head body 8 and connected to the pump body 3 so as to be able to rotate with respect to the pump body 3 about an orientation axis 19 which is transversal to the actuation axis 12. Preferably, the transversal orientation axis 19 is radial with respect to the actuation axis 12 and preferably the transversal orientation axis 19 forms a longitudinal axis of the rotatable column 18. [0041 ]The rotatable column 18 may form a thread 20 screwed into and rotating with respect to a corresponding counter-thread 21 of a connection seat 22 of the pump body 3.

[0042]An accidental unscrewing of the rotatable column 18 from the connection seat 22 can be prevented by means of a striker 23, e.g. a striker pin (figures 3, 4), which can be moved between:

[0043]- an interference position with the rotatable column 18 and the pump body 3 to prevent rotation of the rotatable column 18 beyond an unscrewing limit position, and

[0044] - a non-interference position, which allows the rotatable column 18 to rotate beyond the unscrewing limit position and a complete unscrewing of the rotatable column 18 from the connection seat 22.

[0045]Advantageously, the abutment member or striker 23 is elastically stressed in the interference position.

[0046]According to an embodiment, the rotatable column 18 may internally form a section of a duct 24 for the communication of hydraulic fluid from the pump 2 to the hydraulic actuator 9. For such a purpose, the rotatable column 18 may form a cylindrical sealing surface 25, preferably provided with an annular gasket 26, inserted into a corresponding cylindrical sealing surface 27 of the connection seat 22.

[0047]Making the hydraulic duct directly in the rotatable column 18 protects the hydraulic duct 24 from unwanted deformations and reduces the space required for the structural and hydraulic connections between the pump body 3 and the compression head 7.

[0048]The connection between the rotatable column 18 and the head body 8 is preferably such that it prevents relative rotations therebetween around the transverse orientation axis 19. This allows concentrating, guiding and limiting the angular range of the transverse orientation in a single relative rotation interface.

[0049]According to an embodiment, the tool 1 comprises a support ring 28 connected to the pump body 3 and which supports the head body 8 so as to be able to rotate with respect to the pump body 3 about an orientation axis 29 which is parallel to the actuation axis 12. Preferably, the parallel orientation axis 29 is coaxial to the actuation axis 12 and preferably the support ring 28 has a circumferential and concentric shape with respect to the parallel orientation axis 29.

[0050]The head body 8 is inserted in the support ring 28 and locked so that it cannot move in relation to the support ring 28 along the actuation axis 12, e.g. by means of a shoulder 30 formed by the head body 8 and resting against the support ring 28 and a locking ring 31 accommodated in an annular groove of the head body 8 and resting against the support ring 28 on one side opposite to the shoulder 30. [0051]According to an embodiment, the support ring 28 may internally delimit a section of the duct 24 for the communication of the hydraulic fluid from the pump 2 to the hydraulic actuator 9, e.g. an annular groove 32 formed in an inner surface of the support ring 28 or in an outer surface of the head body 8 and in communication with the hydraulic actuator 9. For this purpose, the head body 8 may form two cylindrical sealing surfaces 33, extending on two opposite sides of the annular cavity 32 and preferably each provided with an annular gasket 34 and in contact with corresponding cylindrical sealing surfaces 35 of the support ring 28, also extending on two opposite sides of the annular recess 32.

[0052]Making the stretch of hydraulic duct directly in the support ring 28 protects the hydraulic duct 24 from unwanted deformations and reduces the space required for the structural and hydraulic connections between the pump body 3 and the compression head 7.

[0053]The connection between the support ring 28 and the pump body 3 is preferably such that it prevents relative rotations therebetween about the parallel orientation axis 29. This allows concentrating, guiding and limiting the angular range of the parallel orientation in a single relative rotation interface.

[0054]Particularly advantageously, the tool 1 comprises a resistance device which prevents a free rotation of the head body 8 with respect to the pump body 3, only by the gravitational effect of the compression head 7, thus allowing a manual adjustment of the orientation of the head body 8, but keeping the head body 8 stationary in the set orientation.

[0055]The resistance device may comprise, for example, one or more friction or snap-in interfaces interposed between the head body 8 and the pump body 3, e.g. said ring gasket 26 or another elastomeric gasket interposed between the rotatable column 18 and pump body 3, and/or said ring gaskets 34 or another elastomeric gasket between the support ring 28 and the head body 8.

[0056]According to a preferred embodiment, the support ring 28 is rigidly connected, preferably formed in one piece, with the rotatable column 18 (figures 3, 4).

[0057]According to a further aspect of the invention, the first compression jaw 14 is permanently connected and oriented with respect to the head body 8 and the second compression jaw 16 is permanently connected and oriented with respect to the cylinder 1 1 , and the tool 1 comprises jaw inserts 36, or so-called dies, which can be reversibly inserted in the compression jaws 14, 16 or into the compression seats 17 to adapt the compression seats 17 to the size of the connection device 100. Each compression jaw 14, 16 forms two opposite side walls 37 which support the respective jaw insert 36 from two opposite sides in the direction of the compression axis 10.

[0058] This allows considerably reducing the size of the replaceable inserts 36 with respect to the size of the detachable jaws of the prior art, and allows a lighter but equally strong construction of the jaws 14, 16 (as they no longer need to be detachable). This reduces imbalances of the tool 1 due to over-heavy jaws and reduces the cost of manufacturing jaws and jaw inserts.

[0059]According to an embodiment, the jaw inserts 36 are magnetically held in the compression jaws 14, 16, e.g. by one or more magnets 44 arranged in a bottom wall of the compression jaws 14, 16 (figure 2).

[0060]According to an embodiment (figure 2, 3), the opposite side walls 37 have a plate shape and are oriented substantially parallel to the actuation axis 12 and tapered towards their free end further away from the actuation axis 12 (according to the variation of shear and bending stresses in the side walls 37). With further advantage, front edges 38 of the side walls 37 facing towards the other jaw, respectively, have an inclination angle 39 towards the other jaw comprised, for example, between 0.5° and 2.0°, which at least partly compensates for elastic deformations of the compression head 7 during compression.

[0061]According to embodiments, the opposite side walls 37 of the compression jaw 14, 16 may be either screwed or forged to the cylinder 1 1 and/or to the head body 8, respectively.

[0062]According to a further aspect of the invention, the head body 8 comprises a tubular wall 40 and a locking pin 41 having two opposite ends accommodated in two opposite holes of the tubular wall 40, wherein:

[0063]the cylinder 1 1 is inserted into the tubular wall 40 in a translatable manner along the actuation axis 12 with respect to the tubular wall 40,

[0064]the piston 13 is inserted into the cylinder 1 1 so that the cylinder 1 1 can translate along the actuation axis 12 with respect to the piston 13,

[0065]the locking pin 41 extends in a transversal (preferably radial) direction with respect to the actuation axis 12 through:

[0066]- a transverse hole 42 (preferably radial) formed in the piston 13 so as to block the piston 13 in integral manner with the tubular wall 40 and prevent relative movements and rotations therebetween,

[0067]- two opposite guiding grooves 43, formed in the cylinder 1 1 , so as to allow the translation of the cylinder 1 1 with respect to the tubular wall 40 along the actuation axis 12 and prevent a relative rotation between the cylinder 1 1 and the tubular wall 40 about the actuation axis 12 (figures 3, 4, 9, 1 1 ).

[0068]The positioning of the locking pin 41 within the axial dimension of piston 13 reduces the unbalance of the tool 1 , the length of the guide grooves 43 and the overall length of cylinder 1 1 . [0069] The locking pin 41 can be extended on the same plane on which also the actuation axis 12 and the compression axis 10 lie and the guide grooves 43 are formed in maximum bending tension zones of cylinder 1 1 during the compression (figures 3, 4, 9, 1 1 ) or, alternatively, the locking pin 41 can be oriented orthogonally to the plane on which the actuation axis 12 and the compression axis 10 lie and the guide grooves 43 are formed in minimum bending tension zones of the cylinder 1 1 during the compression (figure 14). Surprisingly and counter-intuitively, numerical simulations of the overall stress state indicated overall lower stresses of the cylinder 1 1 in the case of position of the locking pin 41 as shown in figures 3, 4, 9, 1 1 , and therefore the possibility of reducing the wall thickness of the cylinder itself.

[0070]According to an embodiment, the locking pin 41 internally forms a section of the hydraulic duct 24 for supplying the hydraulic fluid from the electrohydraulic pump 2 to the hydraulic actuator 9.

[0071]This obviates an arrangement of a separate hydraulic line and protects the hydraulic line section by virtue of the mechanical robustness of the locking pin 41 . This results in a reduction of the number of parts to be assembled, as well as saving of space and reduces the risk of hydraulic oil leakage and gasket wear.

[0072]The section of the hydraulic line 24 formed in the locking pin 41 comprises a longitudinal hole 45 extended in longitudinal direction of the locking pin 41 , and a transverse hole 46, preferably radial to the longitudinal direction of the locking pin 41 , in communication with the longitudinal hole 45 and which leads, preferably on two opposite sides, into an external surface of the locking pin 41 (figures 9, 10, 1 1 , 12).

[0073]The locking pin 41 is positioned and locked in the tubular wall 40 with the transversal hole 46 intersecting and perpendicular to the actuation axis 12. In this manner, the transverse hole 46 is extended at the“neutral fiber” of the section of the locking pin 41 stressed in bending.

[0074]ln order to ensure the correct positioning of the locking pin 41 , the shape of a head 47 of the locking pin 41 exposed to the outside of the tubular wall 40 can be such that the support ring 28 extended about the tubular wall 40 is engaged so as to prevent rotation of the locking pin 41 about the longitudinal axis thereof with respect to the tubular wall 40.

[0075]Advantageously, the outer surface of the locking pin 41 forms an annular cavity 48 in communication with the transversal hole 46 and with a hydraulic supply channel 49 formed in the piston 13 and opened into a pressure chamber 50 of the cylinder 1 1 (figures 4, 13).

[0076]The section of the hydraulic duct 24 formed in the locking pin 41 , in particular the longitudinal hole 45, opens into the section of the hydraulic duct 24 delimited by the support ring 28, in particular the annular slot 32, which in turn is in communication with the section of the hydraulic duct 24 formed in the rotatable column 18.

[0077]The piston 13 may form two cylindrical sealing surfaces 51 in the transversal hole 42, extending on two opposite sides of the annular cavity 48 of the locking pin 41 and preferably provided each with an annular gasket 52 and in contact with corresponding cylindrical sealing surfaces 53 of the locking pin 41 , also extending on two opposite sides of the annular recess 48.

[0078]The figures also show a main annular gasket 54 between the piston 13 and the cylinder 1 1 .

[0079] According to a further aspect of the invention, the hydraulic actuator 9 comprises a return spring 55 inserted in a cavity of the cylinder 1 1 and precompressed between the piston 13 and a reaction cover 56 inserted in the cylinder 1 1 and locked by means of a stopping pin 57. The reaction cover 56 forms two opposite stopping holes 58 and the stopping pin 57 is inserted into the stopping holes 58 of the reaction cover 56 and into the cylinder 1 1 and forms one or two shoulders 59 adjacent to one or both of the stopping holes 58.

[0080]The precompression of the return spring 55 pushes stopping holes 58 of the reaction cover 56 against the stopping screw 57 so that the shoulders 59 of the stopping pin 57 prevent the stopping screw 57 from pulling out from the reaction cover 56. Only a pressure against the reaction cover 56 sufficiently high to overcome the force of the return spring 55 and applied from the outside of cylinder 1 1 can align the stopping holes 58 of the reaction cover 56 with the stopping pin 57 to allow it to pull out. This pressure applied from outside the cylinder 1 1 prevents an uncontrolled expulsion of the reaction cover 56 from the cylinder 1 1. In this manner, during maintenance operations, the preload of the return spring 55 cannot inadvertently catapult the reaction cover 56 out of the cylinder 1 1.

[0081]According to another aspect of the invention, the guide grooves 43 formed in the cylinder 1 1 are positioned and sized so that they never come out of the tubular wall 40 of the head body 8.

[0082]This either reduces or eliminates milling effects between the edges of head body 8 and the guide grooves 43 of the cylinder 1 1 and prevents foreign bodies from falling into cylinder 1 1 .

[0083]According to a further aspect of the invention, the compression head 7 comprises two cylindrical self-lubricating runners 60 placed only in opposite end regions of the head body 8 between the head body 8 and the cylinder 1 1 and absent in a central region of the head body 8 (particularly at the locking pin 41 ). Preferably, the two self-lubricating cylindrical runners 60 form self-lubricating inner linings of the tubular wall 40 of the head body 8. The self- lubricating cylindrical runners 60 advantageously comprise one or more PTFE layers.

[0084]This reduces the friction caused by the bending of cylinder 1 1 due to the distance between the actuation axis 12 of the hydraulic actuator 9 and the compression axis 10 of the jaws 14, 16 and the connection device 100, and optimizes the use of the self-lubricating material.

[0085] The electro-hydraulic pump 2 may comprise an electric motor 61 which can be powered by a rechargeable battery 62, a hydraulic pump 63 connected to motor 61 in order to increase the pressure of the hydraulic fluid in response to the movement of motor 61 , as well as an electronic control circuit 64 connected to the electric motor 61 , to the battery 62 and to operating button 5 to control the electric motor 61 .