EP2480379A1

EP2480379A1 - Gripping tool

Info

Publication number: EP2480379A1
Application number: EP10773648A
Authority: EP
Inventors: Fabrice Petit
Original assignee: Gillet Group S A
Current assignee: Gillet Group S A
Priority date: 2009-09-24
Filing date: 2010-09-24
Publication date: 2012-08-01
Anticipated expiration: 2030-09-24
Also published as: EP2480379B1; US20110233949A1; WO2011036355A1; FR2950278A1; CA2775401A1; FR2950278B1

Abstract

The invention relates to a tool for gripping (1) a mechanical part (4), comprising: a bell (3) provided with gripping means (2), a rotatably movable housing (5) coaxial to said bell (3), comprising at least one side window (54) and receiving said mechanical part (4), three bearing elements (7), one of which is a movable retractable rotary roller, said bell (3) being provided with at least one slope (31) for varying the center-to-center distance between said retractable rotary roller (7) and said bell (3) in accordance with the angular position of said retractable rotary roller (7), said housing (5) and said retractable rotary roller (7) being connected by guide means (55, 8) for guiding said retractable rotary roller (7), said housing (5) and said guide means (55, 8) enabling the radial movement of said retractable rotary roller (7) such that the pin thereof can pass through the wall of said housing (5).

Description

GRIPPING TOOL

The present invention relates to a gripping tool for mechanical parts, in particular a ball joint, this gripping tool being intended for the gripping of mechanical parts, such as, for example, tulips of ball joints, and to facilitate their coupling and uncoupling with others. mechanical elements.

Some mechanical parts of cylindrical or spherical shapes are particularly difficult to handle with precision and force, especially when it comes to couple and decouple other mechanical elements.

This is for example the case of gougeons, rod-shaped mechanical members having a threaded portion and a smooth portion, some uses require gripping by the smooth portion. Due to the cylindricity of the smooth part, it is difficult to maintain the gudgeon forcefully without damaging its smooth surface. There are commercially available specific tools called gougeons extractors that can strongly grip the smooth and cylindrical portion of the gudgeon while preserving it. A dowel extractor comprises a cylindrical hollow body provided for example on its outer surface with hexagon allowing the engagement of a wrench. The dowel extractor further comprises a hollow cylindrical sleeve housed in the hollow body. This sleeve is provided in its wall with three slots having a V-shaped profile so that the widest part of each groove is oriented towards the outer surface of the sleeve and the less flared portion of each groove is oriented towards the axis of the sleeve. Each groove receives a ball, thus housed between the sleeve and the hollow body. The inner surface of the hollow body defines six slopes against which the balls roll. The distance between the balls and the axis of the sleeve therefore varies according to the position of the balls along the slopes. Each puller, of gougeons is dedicated to specific diameters of gougeons imposed by the dimensions of the sleeve, the hollow body, the balls and the shape of the slopes. Also, gougeons extractors are often sold in a box to provide a range of compatible diameters. These boxes are of course more expensive than a puller gougeons simple and much less easy to use. In addition, during use there is a risk of losing one or other of the dart pullers. It is also difficult to anticipate the diameters of future gougeons that we will have to disassemble and therefore choose the right box. There is therefore a need for a gougeon extractor compatible with various gougeon diameters over a wide range of values.

The problem is similar for knee joints. A ball joint is an articulation made of a first piece of spherical shape, called a ball joint, and a second piece, called a tulip. The tulip has a cylindrical outer shape and a spherical inner shape receiving the ball that can rotate and be oriented in all directions relative to the tulip. The patella is usually coupled to a swivel rod and the tulip to a steering bar. In practice, at least one of the rotational directions of the ball joint is limited by the presence of the ball rod and the steering bar. The ball joint, however, allows to achieve significant angulation angles between the ball rod and the steering bar.

The joints of the ball-and-socket type are mechanical elements that are commonly used, particularly in industry automobile, and in particular to equip the management of motor vehicles. Arranged between the steering shaft and the wheels of the vehicle, the hinged joints make it possible to pivot the wheels of the vehicle while allowing their rotation and thus the mobility of the vehicle. Manufacturers propose standardized joints patellae, the ball joint being already nested in the tulip in which it is locked in translation. To couple the ball joint to other mechanical elements, it is necessary to firmly hold the ball joint to, for example, screw the steering bar on a transmission bar. This operation is made difficult by the great rotational mobility existing between the ball and the tulip and the cylindrical shape of the tulip. A similar difficulty arises to decouple the ball joint, for example from the transmission bar.

There are commercially available specific tools called "ball head" which allow to handle effectively, holding the handle of the ball joint, the outer cylindrical shape of the tulip. An example of known ball joint removal is illustrated in FIGS. 1 to 3 in which:

FIG. 1 is a view in axial section, along the section line BB of FIG. 2, of the known ball joint, this ball joint containing a ball joint represented in the form of a single piece,

FIG. 2 is a radial sectional view, along line AA of FIG. 1, of the ball-and-socket remover of FIG. 1, the ball-and-socket remover containing a ball joint, and

FIG. 3 is an exploded perspective view of the ball-and-socket remover of FIG.

With reference to these figures, the ball joint 100 traditional comprises a tube 101 for receiving the ball rod 102 and allowing remote access to the ball joint type. Indeed, the ball joints are generally placed under the calender of the vehicle where, due to the presence of other mechanical members, there is little room for access to the ball joints. A first end of the tube 101 is provided with six sockets 103 allowing the engagement of a clamping wrench (not shown), for example a ratchet. A second end of the tube 101 is provided with a bell 104 intended to receive, in the extension of the ball rod 102, the tulip 103 containing the ball (the ball is not differentiated from the tulip 103 in FIGS. 3).

The ball joint 100 also has a flange 105 housed in the bell 104 and intended to receive the ball joint. The flange 105 is provided in two parts interconnected by three spacers 106 distributed at regular intervals on the periphery of the flange 105. The bell 104 is provided with a thrust washer 107 and an elastic ring 108 coupled to a washer support 109 preventing lateral displacement of the flange 105 relative to the tulip 104. Each portion of the flange 105 has three radial grooves 110 facing each other in pairs and in which are inserted rotating rollers 111. Each rotary roller 111 is thus movable in rotation about its own axis and movable in radial translation along the radial groove 110 relative to the flange 105. The race of the rotary rollers 111 is limited, inwardly, by a continuous circular portion of the flange 105 which gives the flask 105 its mechanical strength and, outwardly, by the inner face of the tulip 104 against which the rotating rollers 111 roll. The inner surface of the tulip 104 defines six slopes 112 against which the rotating rollers 111 roll. The six slopes 112 form three lobes defined by their points and their hollows. The distance between the rotary rollers 111 and the axis of the ball joint 100 thus varies according to the position of the rotary rollers 111 along the slopes 112. The rotary rollers 111 are also biased towards the axis of the ball joint 100 by elastic rings 112 including, on either side of the flange 105, the three axes of the rotary rollers 111.

The known ball joint 100 can receive ball joints of different diameters. Nevertheless, the maximum diameter that can be grasped by the ball joint is defined by the internal dimensions of the flange 105 which receives the ball joint, itself limited in size by the tulip 104 in which it is housed. It is common that the range of compatible diameters is thus between 35 and 40.5 mm. The design of the current ball joint does not allow to accept larger diameters which poses a problem for the assembly and disassembly of these hinges joints of larger diameters.

One solution is to increase the outer and inner dimensions of the tulip 104 so that it can receive a flange 105 of larger dimensions. This solution is expensive since it requires the manufacture of a new tulip different and therefore additional manufacturing tools compared to those already used for the standard tulip. Due to its superior dimensions, the new tulip requires more raw material to be made. Finally, the upper outer dimensions of this tulip are incompatible with the very limited free space in the immediate environment of the ball joints to be dismantled. This solution is therefore unsatisfactory and there remains the need for a ball joint dismount compatible with Ball joint diameters varied over a wide range of values.

In addition, beyond the dimensional limitations they present, the known ball joints have a large number of parts, making their costly manufacture and difficult assembly. Furthermore, during their normal use, they are subjected to significant mechanical stress, and their robustness is not always satisfactory, including the rigidity of the angular positioning of the flanges between each other.

In general, there is the need for a gripping tool for gripping in particular cylindrical and spherical surfaces of different diameters that this gripping tool is a puller dowels, a ball joint, a disassembly axis or any other gripping tool similar.

The present invention aims at remedying the drawbacks previously described by providing a gripping tool of limited external dimensions, substantially similar to those of the current corresponding tools, adapted to receive mechanical parts of various dimensions to handle it with force, this gripping tool being robust, easy to manufacture and of moderate cost.

The invention relates to a gripping tool including a mechanical part, comprising at least:

a bell provided with a gripping means facilitating the manipulation of the bell,

- A cage coaxial with the bell and rotatable in the bell, the cage having at least one side window through the wall of the cage, the cage defining a housing for receiving the mechanical part, three bearing elements including at least one retractable rotary roller movable radially with respect to the side window,

the inner face of the bell being provided with at least one slope arranged to vary the spacing between the retractable rotary roller and the bell according to the angular position of the retractable rotary roller relative to the bell, the cage and the roller retractable rotary joint being interconnected by guide means arranged to radially guide the retractable rotary roller during the variation of center distance, remarkable in that the cage and the guide means are arranged to allow the radial displacement of the retractable rotary roller of so that its axis can cross the wall of the cage.

Thus, the minimum diameter of the mechanical part that can be held by the gripping tool is not limited by the dimensions of the cage. In addition, the gripping tool can also accommodate significant variations in the diameters of the mechanical parts that it receives.

The guide means are arranged to allow the inclination of the retractable rotary roller relative to the axis of the bell. This particular construction allows the gripping tool to adapt to non-perfectly cylindrical geometries of mechanical parts, for example conical parts or having a curved profile. In addition, the inclination of the retractable rotary roller makes it possible to better withstand certain mechanical stresses and thus gives greater strength to the gripping tool. Finally, this inclination facilitates the insertion of mechanical parts in the ball joint.

The guide means advantageously comprise at least one pivot axis provided on the cage, and at least one pivoting arm connecting the pivot axis to the roller retractable rotary. The gripping tool may also comprise two pivoting arms each connecting the pivot axis to the retractable rotary roller, the pivoting arms being angularly movable relative to each other with respect to the pivot axis.

The cage is preferably provided with at least one stop arranged to limit the pivoting of the pivoting arm towards the axis of the cage.

According to a preferred embodiment, the cage comprises two flanges interconnected by at least one rod, of axis substantially parallel to that of the cage, and defining at least partly the pivot axis. This construction is particularly robust and allows the gripping tool to better cash the mechanical stresses to which it is subjected during use.

The gripping tool advantageously comprises elastic means provided between the retractable rotary roller and the cage and arranged to bias the displacement of the axis of the retractable rotary roller towards the axis of the cage.

The elastic means comprise for example at least one torsion spring comprising turns, at least a portion of the turns of which is carried by the pivot axis, the torsion spring being provided with a first and a second limbs extending on either side of the turns, one of the first and second branches defining the pivoting arm, the other being in abutment against the cage.

The torsion spring may comprise two portions of turns separated by an intermediate branch defining the second branch, the torsion spring having two first branches arranged on either side of the two portions of turns.

Advantageously, the cage comprises three side windows separated two by two by angles substantially equal, three retractable rotating rollers, each provided in front of one of the side windows. The gripping tool thus ensures isostatic gripping which distributes the forces undergone in a homogeneous manner and thus reinforces the robustness of the gripping tool.

The cage is preferably formed of a single piece making the gripping tool more robust and less sensitive to torsional stresses. Thus, the relative position of the flanges relative to each other is stable over time.

The bell may be coupled to a tube, forming at least partly the gripping means, and intended to receive a portion of the mechanical part. This tube facilitates the handling of the gripping tool.

The retractable rotary roller is advantageously composed of several rollers whose axes may be inclined relative to each other or tilted so as to better cooperate with mechanical parts having a curved profile or having two slopes in contra. This differentiated inclination of the rollers also makes it possible to better follow the profile of the mechanical part and thus to make its insertion easier.

In order to facilitate the understanding of the invention, the following description is non-limitingly centered on a ball joint. It is understood that the invention relates more generally to a gripping tool adapted to receive mechanical parts of various dimensions, these parts may have an outer cylindrical shape, square, hexagonal, oval, and a rectilinear profile or not, for example bulging. It may for example be a puller gougeons, a disassembly axis or any other similar tool.

The invention is described below, by way of non-limiting example, with reference to the accompanying drawings on which :

FIG. 4 is a view in axial section along the section line CC in FIG. 5 of the ball joint according to the invention, the ball joint being shown with a ball joint shown schematically in the form of a single piece, the ball joint disassembly including an inner cage and a body;

• Figure 5 is a radial sectional view along the section line DD of Figure 4, the ball joint of Figure 4 and a ball joint;

FIG. 6 is an exploded perspective view of the ball-and-socket remover of FIG. 4;

FIG. 7 is a view in axial section, along the section line CC of FIG. 5, of the body of the ball-and-socket remover of FIG. 1;

• Figure 8 is a perspective view of the inner cage of the ball joint of Figure 4, the cage being provided with rollers, holding pins and springs.

The gripping tool according to the invention is described with reference to a ball joint shown in Figures 4 to 8. For greater clarity, the ball joint 4 is shown schematically in these figures by a single hatched block. In known manner, the ball joint 4 comprises a tulip 40 containing the ball 41 coupled to a ball rod 42. The tulip 40 itself can be coupled to a steering bar 43.

With reference to FIG. 4, the ball joint 1 according to the invention comprises a handle 2 coupled to a bell 3 receiving a cage 5.

The handle 2 comprises a tube 20 extending axially and whose first end is provided with a bead 21 for locking the bell 3 when it is fitted on the tube 20. The second end of the tube 20 is coupled to a sleeve 22 housed in the tube 20 and provided at its end free of hex 23 for the engagement of a wrench (not shown), for example a ratchet. As detailed below, the tube 20 can receive the ball rod 42 of a ball joint 4 which is to be grasped by means of the ball joint 1. The handle 2 makes it possible to manipulate the bell 3 at a distance and facilitates the gripping of the ball. kneecaps not very accessible.

bell 3 is disposed in the extension of the handle 2 on which it is fitted to abut against the bead 21. The bell 3 can be force-fitted on the handle 2 and / or glued, welded or fixed by any other means adapted. The bell 3 comprises coaxial bores of different diameters including in particular a main bore 30, shown in FIG. 7, and intended to receive the cage 5. This main bore 30 comprises, on either side of a cylindrical section, six slopes 31, curved, forming a three-lobe shape provided with three points and three recesses. The function of the slopes 31 is detailed below.

The cage 5 is mounted coaxially with respect to the bell 3 in which it is housed, movable in rotation. The cage 5 defines a housing 50 intended to receive the tulip 40 of the ball joint 4. The cage 5 comprises two flanges 51, 52 interconnected by a circular wall 53 traversed by side windows 54 of substantially similar shapes and dimensions and distributed at regular intervals on the circular wall 53. The flange 51 is provided with a return 57 which limits the axial insertion of the joint 4 ball in the ball joint 1 by preventing the passage of the tulip 40 in the hole defined by the return 57.

The flanges 51, 52, are also interconnected by three rods 55, axes parallel to that of the cage 5, and each disposed facing one of the windows 54. Each of these rods 55 serves as a pivot axis to a retractable rotary roller 7 provided opposite a window 54. For this purpose, the retractable rotary rollers 7 are individually connected to a rod 55 by the first branches 80 of a torsion spring 8 also comprising two portions of connected turns between them by an intermediate branch 81 (or second branch) offset radially with respect to the portions of turns. The portions of turns are carried by the rod 55 and the intermediate branch 81 bears against the circular wall 53. The first branches 80 of each torsion spring 8 thus form pivoting arms enabling the retractable rotary rollers 7 to pivot around the rods 55, through the side windows 55.

The retractable rotary rollers 7 are cylindrical and comprise a running surface surrounded by tips of smaller diameter, each of these lower diameters being housed in one of the loops formed at the free ends of the first branches 80. Thus, each retractable rotary roller 7 is urged , by the torsion spring 8 bearing by the intermediate branch 81 on the cage 5, towards the axis of the cage 5 and the bell 3.

In addition, each retractable rotary roller 7 is rotatable about its own axis, locked in the loops of the torsion spring 8. The torsion spring 8 allows the individual and dissociated mobilization of each of the first branches 80. Thus, the rollers retractable rotary 7 may be inclined relative to the axis of the cage 5 and therefore relative to the axis la bell 3. This inclination allows the ball joint 1 to be able to grip mechanical parts of shapes other than cylindrical, for example mechanical parts conical, spherical or having an irregular circumference. In addition, this inclination facilitates the introduction of mechanical parts into the ball joint 1.

In front of each lateral window 54, the cage 5 is provided with two stops 56 provided opposite one another on each flange 51, 52. One of these stops 56 is shown in FIG. 8. These stops 56 limit the inward pivoting of the first branches 80 and thus the radial displacement towards the inside of the retractable rotary rollers 7.

During the tightening operation around the tulip 40, the radial outward spacing of the retractable rotary rollers 7 is prevented by the support of the retractable rotary rollers 7 against the slopes 31. The angular displacement of the cage 5 by relative to the bell 3 and the support of the retractable rotary rollers 7 on the slopes 31 has the effect of varying the spacing between the retractable rotary rollers 7 and the cage 5. As described later, this shift extends to that the retractable rotary rollers 7 are in a wedging configuration between the slopes 31 and the tulip 40. The tulip 40 is then firmly held by the ball joint 1.

During this variation of center distance, the retractable rotating rollers 7 can circulate radially through the side windows 54. The radial displacement towards the inside of the retractable rotary rollers 7 is limited by the stops 56 which receive the support of the first branches 80 Thus, the retractable rotary rollers 7 do not exceed a predetermined minimum limit position limiting the effort required to provide insertion of the ball joint 4.

The minimum gripping diameter, corresponding to the minimum diameter of the mechanical part that can be held by the ball joint 1, is determined by the position of the retractable rotary rollers 7 when they are closest to the axis of the cage 5. When the cage 5 is provided with stop 56, this position is determined by the stops 56. The maximum gripping diameter, corresponding to the maximum diameter of the mechanical part that can be held by the ball joint, is defined by the position of the rotary rollers retractable 7 when they are in the tips of the lobes formed by the slopes 31. The range of diameters of mechanical parts that can be grasped by the ball joint 1 according to the invention is therefore wider than that of known ball joints. With comparable external dimensions, for example, a range of between 35 and 40 mm is limited to a range of at least 35 to 45 mm.

The cage 5 is locked in axial translation in the bell 3 on the one hand by the support of its flange 51 against a boss formed by the end of the main bore 30, on the other hand via a elastic ring 6 housed in a circular groove 33 provided at the entrance of the bell 3. The flanges 51, 52 and the circular wall 53 may be formed in one piece, for example a molded part.

In an alternative embodiment not shown, each rod is replaced by two studs provided facing each other respectively on each of the flanges. The turns portions of the torsion spring are fitted on each of the studs so that these coil portions cooperate with the studs to define the pivot axis of the roller.

In another variant embodiment shown, each retractable rotary roller is coupled to the rod by two rigid lateral pivoting arms. Each of these pivoting arms is biased by elastic return means tending to move each pivoting arm, radially inwardly, and thus the corresponding retractable rotary roller in the same way. Each pivoting arm can thus be biased by means of a torsion spring similar to those described above.

The return means may also comprise two elastic rings provided around the cage, placed on either side of the rotary rollers retractable on their small diameters, so as to jointly solicit the radial displacement inwards of the retractable rotary rollers. The return means may finally comprise leaf springs.

In yet another embodiment not shown, each retractable rotary roller is composed of several aligned rollers. To increase the adaptability of the ball head to mechanical parts having non-regular or curved outer surfaces, these rollers can be articulated relative to each other. The rollers may for example be carried by a flexible shaft biased on both sides of the two rollers by two resilient pivoting arms. It is possible to provide a third pivoting arm between the rollers. The flexible shaft may also be coupled to rigid pivoting arms biased by elastic return means. The rollers can each be carried by an independent shaft, each shaft being individually coupled to pivoting arms. When the retractable rotary roller is composed of two aligned rollers carried by a single shaft, each retractable rotary roller can be solicited by a single pivoting arm whose end connecting the single shaft is arranged between the rollers constituting the retractable rotary roller.

In variant embodiments not shown, the gripping tool can have the following different configurations:

a retractable rotary roller coupled to two rotary rollers of fixed axes (non-retractable),

two retractable rotary rollers coupled to a rotary roller of fixed axis (not retractable),

a retractable rotary roller coupled to two fixed stops (non-rotating),

two retractable rotating rollers coupled to a fixed stop (non-rotating).

The fact of having three points of support, formed by the rotating rollers retractable or not and fixed stops, provides a reliable and effective isostatic gripping of the mechanical part. The gripping tool may nevertheless have a higher number of support points.

A procedure will be described below for using the ball joint 1.

During the insertion step, the ball joint 1 is held by means of the handle 2 in order to approach the bell 3 of the ball joint 4 to be gripped, and to insert this ball joint 4 into the ball joint 1. The insertion is limited by the tulip 40 which abuts against the return of the flange 51 of the cage 5. Once inserted, the ball rod 42 is received in the tube 20, the tulip 40 is received in the bell 3 and in particular in the cage 5 between the retractable rotary rollers 7. During the insertion of the tulip 40 into the bell 3, the inclined surface of the tulip 40 comes into contact with the retractable rotary rollers 7, radially inwardly biased by the torsion springs 8, themselves pivoting around the rods 55. The elasticity of the first branches 80 allows the retractable rotary rollers 7 of tilting with respect to the axis of the bell 3 and thus follow, to a certain extent, the profile of the tulip 40 during its insertion. Once the tulip 40 has been inserted in the bell 3, the retractable rotary rollers 7 bear against the outer surface of the tulip 40, radially biased inwards by the torsion springs 8.

During the clamping step, the handle 2 of the ball joint 1 is then manually turned counterclockwise about its axis, causing the angular displacement of the bell 3 and its slopes 31 and thus the rolling of the retractable rotary rollers 7 on the outer surface of the mechanical part. This rolling is continued until the retractable rotating rollers 7 are stuck, towards the hollow lobes formed by the slopes 31, between the slopes 31 and the mechanical part to be gripped. As for the known ball joints, the slopes 31 and the diameters of the retractable rotary rollers 7 are chosen to cause effective jamming of the retractable rotary rollers 7 on the mechanical part. The mechanical part is therefore firmly held by the ball joint 1. It can thus be easily handled, for example to unscrew the steering bar 42 of the ball joint 4 of a transmission bar (not shown).

It is clear from the description that the gripping tool 1 according to the invention allows, while having limited external dimensions, to receive mechanical parts of variable dimensions, over an extended range of values, greater than that allowed by the disassembly. ball joints and other known gripping tools. The gripping tool 1 thus provides access to mechanical parts in congested environments. In addition, the gripping tool 1 has a limited number of parts which reinforces its reliability and its lifetime.

It is understood that the examples described are only particular illustrations in no way limiting the fields of application of the invention. Those skilled in the art may provide arrangements of size, shape and material to the particular embodiment without departing from the scope of the present invention.

Claims

1. Gripping tool (1) including a mechanical part (4), comprising at least:

a bell (3) provided with gripping means (2) facilitating the manipulation of said bell (3),

a cage (5) coaxial with said bell (3) and rotatable in said bell (3), said cage (5) having at least one side window (54) passing through the wall of said cage (5), said cage ( 5) defining a housing (50) for receiving said mechanical part (4),

three bearing elements (7) including at least one retractable rotary roller movable radially with respect to said lateral window (54),

the inner face of said bell (3) being provided with at least one slope (31) arranged to vary the spacing between said retractable rotary roller (7) and said bell (3) as a function of the angular position of said rotary roller retractable (7) relative to said bell (3), said cage (5) and said retractable rotary roller (7) being interconnected by guide means (55, 8) arranged to radially guide said retractable rotary roller (7 ) during the variation of center distance, characterized in that said cage (5) and said guide means (55, 8) are arranged to allow the radial displacement of said retractable rotary roller (7) so that its axis can pass through the wall of said cage (5).

2. Gripping tool (1) according to claim 1, characterized in that said guide means (55, 8) are arranged to allow the inclination of said retractable rotary roller (7) relative to the axis of said bell ( 3).

3. gripping tool (1) according to any one of claims 1 or 2, characterized in that said guide means comprise at least one pivot axis (55) provided on said cage (5), and at least one arm pivoting member (80) connecting said pivot axis (55) to said retractable rotary roller (7).

4. Gripping tool (1) according to claim 3, characterized in that it comprises two pivoting arms (80) each connecting said pivot axis (55) to said retractable rotary roller (7), said pivoting arms being angularly movable between them with respect to said pivot axis (55).

5. gripping tool (1) according to any one of claims 3 or 4, characterized in that said cage (5) is provided with at least one stop (56) arranged for limited pivoting of said pivoting arm (80) towards the axis of said cage (5).

6. Gripping tool (1) according to any one of claims 3 to 5, characterized in that said cage (5) comprises two flanges (51, 52) interconnected by at least one shaft (55) of axis substantially parallel to that of said cage (5) and defining at least in part said pivot axis.

7. Gripping tool (1) according to any one of the preceding claims, characterized in that it comprises elastic means (8) provided between said retractable rotary roller (7) and said cage (5) and arranged to solicit the displacement of the axis of said retractable rotary roller (7) towards the axis of said cage (5).

8. Gripping tool (1) according to any one of claims 3 to 7, characterized in that said elastic means comprise at least one torsion spring (8) having turns, at least a portion of the turns is carried by said pivot axis, said torsion spring (8) being provided with first and second legs (80, 81) extending on either side of said turns, one of said first and second branches ( 80, 81) defining said pivoting arm, the other being in abutment against said cage (5).

9. gripping tool (1) according to claim 8, characterized in that said torsion spring (8) comprises two portions of turns separated by an intermediate branch (81) defining said second branch, said torsion spring (8) comprising two first branches (80) disposed on either side of said two portions of turns.

10. Gripping tool (1) according to any one of the preceding claims, characterized in that said cage (5) comprises three side windows (55) separated in pairs by substantially equal angles, three retractable rotary rollers (7). , each provided in front of one of said side windows (55).

11. Gripping tool (1) according to any one of the preceding claims, characterized in that said cage (5) is formed of a single piece.

12. Gripping tool (1) according to any one of the preceding claims, characterized in that said bell (3) is coupled to a tube (2) forming at less in part said gripping means and intended to receive a portion of said mechanical part (4).

13. Gripping tool (1) according to any one of the preceding claims, characterized in that said retractable rotary roller (7) is composed of several rollers.