FR2767279A1 - COUPLING DEVICE FOR GRIPPING JAW - Google Patents

Abstract

This coupling device, for a gripping device (1), allows the detachable coupling of a gripping jaw (4) on a gripping jaw support (5). The gripping jaw (4) is provided with a coupling shoe (14) which can be nested on a base receiver (13) provided on the gripping jaw holder (5). Suitable receiving surfaces, provided on the base receiver (13), which are capped by coupling branches of the coupling shoe (14), ensure good retention of the nested gripping jaw (4). Since both assembly and disassembly can be carried out without tools, it is easy to handle.

Description

The invention relates to a coupling device intended to produce

  the detachable coupling of a gripping jaw, having a gripping part, with the gripping jaw support of a gripping device capable of being used for handling objects, comprising a basic receiver provided or capable of be mounted on the gripping jaw support, and comprising a coupling shoe provided or capable of being mounted on the gripping jaw, which is capable of being fitted, from the front face, in a direction of fitting, on the base receiver, two receiving surfaces, turned in opposite directions and oriented perpendicular to the gripping direction of the gripping part, being provided on the base receiver and the coupling shoe having two coupling branches , facing each other with a gap, by means of which it covers the two receiving surfaces,

  in the nested coupling position.

  In the field of handling, for example in the case of the production and assembly of objects of any kind, gripping devices are commonly used, also called grippers, by means of which the various components can be entered and placed in a designated location. The gripping devices can, in this case, be provided on a handling system, by means of which they can be moved as desired. The gripping device, for its part, is generally equipped with at least two gripping jaw supports, on each of which a gripping jaw can be fixed; by actuating, for example pneumatically, the gripping device, it is possible to obtain a gripping movement of the support of gripping jaws and of the gripping jaws which are fixed thereto, so that a gripping part, located on the gripping jaws, grips the object to be handled, in a gripping direction. Admittedly, in known gripping devices, there is already the possibility of mounting, on the gripping jaw supports available, gripping jaws adapted to the application considered. For this purpose, each gripping jaw support constitutes a basic receiver of parallelepiped shape, and the gripping jaw which is associated therewith has a one-piece coupling shoe, by means of which it can

  be fitted onto the associated gripping jaw support, to then be fixed there by screwing.

  In the case of different gripping operations to be carried out, the whole of the gripping device has generally been exchanged until now, which is replaced by a gripping device equipped with jaws of different shape. Generally, it is not enough to simply change the gripping jaws, because of the impractical conformation of the coupling.20 This however involves relatively high costs and impractical adjustments, in order to correctly orient the newly gripping device again. installed. The object of the present invention is to propose provisions making it possible to change the gripping jaws in a simpler, faster manner, but in a precise manner. To achieve this goal, it is provided: that the first receiving surface is located between a front retaining projection and a rear retaining projection, having a certain distance, in the nesting direction, relative to the latter, the first receiving surface and the two holding projections delimiting a holding recess, in which the associated coupling branch engages by complementarity of shapes, in the coupling position, by a coupling part having the same width, in the nesting direction, that the second opposite receiving surface extends obliquely and has, in the front zone, a distance from the first receiving surface which is smaller than in the rear part, this surface being delimited, in the rear area, by a projection forming a stop on which the second coupling branch associated with the coupling shoe rests in the coupling position ent, an intermediate space, widening towards the front face of the second receiving surface, existing simultaneously between the second coupling branch and the second oblique receiving surface, intermediate space which allows the coupling shoe to pivot , with respect to the base receiver, in an inclined position, in which the rear end section, oriented opposite the direction of fitting, of the coupling part of the first coupling branch does not cooperate with the holding recess and that is provided, on the second coupling branch, at least one pressing element, subjected to the action of a spring, which, in the coupling position, acts on a zone before the second opposite oblique receiving surface, crossing the intermediate space, and thus presses the second coupling branch against the projection forming a stop, the coupling shoe being able to be pivoted in the tilted position by overcoming the element's pushing force

presser.

  There is thus a coupling device which allows, manually or automatically, to change the gripping jaw quickly and without tools. In addition, precise positioning is constantly obtained when the shoe is fitted into the coupling position, without additional adjustment. The attachment of the coupling shoe and the gripping jaw which is attached thereto is obtained, at least in the direction of fitting, by complementarity of shapes, insofar as the coupling part enters the holding recess associated with it. This coupling position is maintained by the pressing element, which pushes the shoe against the projection forming a stop, by acting on the second associated oblique receiving surface, which has the consequence that the coupling part is located inside. of the holding recess. Maintaining the mating position is

  thus ensured by an elastic force.

  To change a gripping jaw, a relative pivoting movement takes place between the coupling shoe and the base receiver, during which the coupling part is placed obliquely, overcoming the pushing force of the pressing element placed under the action of a spring, so that it can be brought to pass in front of the front retaining projection,

  when fitting and removing the coupling shoe.

  Since the pivoting movement, like the elastic force, takes place perpendicular to the gripping direction of the gripping part, it is not possible for the connection to come off inadvertently during subsequent operation. The gripping force does not act in the direction of the change force that must be exerted to effect a change of jaws. The use of the coupling device is not limited to certain dimensions of gripping devices; it can be used both for grippers for indoor use and for grippers for outdoor use. When changing the gripping jaw, since the gripping device itself can remain in place and therefore there is no need to change the connections to the electrical and fluid networks, which are necessary to make operate the gripping device, handling

turns out to be extremely simple.

  In order to obtain secure attachment of the coupling shoe in the nested coupling position, a relatively high elastic force is advantageously chosen for the pressing element. However, since the biasing direction of the pressing element is perpendicular to the nesting direction, it is advantageous to take arrangements which facilitate the process of fitting the pressing element, and thus of its insertion. Such an arrangement may consist in that the coupling part, provided on the first coupling branch, has, on the inner face, oriented in the direction of the first receiving surface, approximately at the same height as the pressing element provided on the second coupling branch, a recess in which, when the coupling shoe is fitted, the front retaining projection can penetrate in order to simultaneously position the pressing element on the front zone of the second oblique receiving surface, in passing over the front face of the part of the base receiver which has the second receiving surface. Once the pressing member is on the second receiving surface, the elastic force can be overcome relatively easily by tilting or pivoting the coupling shoe. It is advantageously provided that the gripping force, which acts on the gripping part when the gripping device is used, is absorbed only by complementarity of shapes. For this purpose, it is possible to provide, on the base receiver, bearing surfaces, oriented opposite each other, and extending perpendicular to the receiving surfaces, on which the coupling shoe s' supports, by counter-abutment surfaces, in the

coupling position.

  The above can be carried out in a particularly simple way if the coupling shoe is shaped like a frame, the two coupling branches being formed by opposite frame branches, and the counter-stop faces being located. on the inner faces of the transverse branches which

  extend between the coupling legs.

  To allow, in particular, to equip existing gripping devices, it is advantageous that the basic receiver constitutes a separate component, which can be fixed in a removable manner on a support of

  gripping jaw, for example by screwing.

  The invention will now be described in more detail with the aid of the appended drawing, in which: FIG. 1 is a side view of a possible embodiment of a gripping device on which are mounted, at by means of a preferred coupling device according to the invention, two gripping jaws protruding downward, which hold an object indicated schematically in phantom, Figure 2 is a front view of the gripping device of Figure 1, seen in the direction of arrow II in FIG. 1, FIG. 3 is a cross-sectional view of the gripping device of FIG. 1, in the area of

  coupling device, along cutting line III-

  III, FIGS. 4 to 7 are views in longitudinal section of the coupling device, along the section line IV- IV of FIGS. 1 and 3, various assembly phases occurring during the coupling of the shoe being shown, and FIG. 7 representing the shoe in the nested coupling position also illustrated in FIGS. 1 and 3, and FIG. 8 shows, according to a mode of representation corresponding to that of FIGS. 4 to 7, the initial displacement phase when one remove the hoof

  base receiver coupling.

  Figures 1 and 2 show a gripping device 1 capable of being fixed, by means of fixing devices 2, on a handling device not shown in detail. The handling device has drive means which make it possible to move and position the gripping device 1 as desired, in order to move an object 3, shown by way of example, between different places. The gripping device 1 is equipped with several gripping jaws 4 which are each fixed on a support 5 of gripping jaws and which

  protrude from the housing 6 of the gripping device 1.

  The gripping jaws 4 of the exemplary embodiment face each other, with a gap, and have, on the facing faces, a gripping part 7 of which

  the shape is adapted to the shape of the objects 3 to be handled.

  In the housing 6 of the gripping device 1 is a drive device not shown in detail, which, in the exemplary embodiment, is capable of being actuated by a fluid, thanks to a pressurized fluid constituted, in particular, pressurized air, which can be introduced and evacuated by fittings 10. The drive device cooperates with the supports 5 of gripping jaws and makes it possible to move these, with the gripping jaws 4 which are there fixed, one in the direction of the other, in a gripping direction 8, and one opposite the other, in an opposite release direction 9. When moving in the gripping direction 8, the gripping parts 7 act on the object 3, so that the latter can be grasped, maintained and transported and positioned, with the gripping device 1, by the handling device. Since the internal structure of the gripping device 1 as such is known, it

  will not be made a detailed description of it.

  The gripping jaws 4 are detachably mounted on the supports 5 of gripping jaws, so that if necessary, they can be exchanged for gripping jaws of another shape. This exchange can be carried out purely manually, without using any particular tool, or automatically, by means of a suitable exchange device. This is ensured by a particular coupling device 12, which is associated with each pair that form

  the gripping jaw 4 and the gripping jaw support 5. It will be described below.

  afterwards, with particular reference to FIGS. 3 to 8. The coupling device 12 has a base receiver 13 provided on the grip jaw support 5, as well as a coupling shoe 14 provided on the grip jaw 4, capable of being detachably coupled with the base receiver 13. The mounting of a gripping jaw 4 disassembled on the support 5 of associated gripping jaw is produced by fitting the latter, with the coupling shoe 14, in the base receiver 13, in a nesting direction, and by engaging it in a certain way. The nesting direction 15 is perpendicular to the gripping direction 8, the nesting on the base receiver 13 taking place from the front face 16 of the base receiver 13, which is oriented opposite the housing 6 The nesting direction therefore extends approximately in the longitudinal direction of the supports 5

  gripping jaws protruding from the housing 6.

  In the embodiment, the base receiver 13 is a separate component from the support 5 of gripping jaws which is associated therewith, detachably fixed on this support 5. Thus, it is possible that a support for jaws of gripping device is only fitted with a base 13 receiver when necessary. There is also the possibility of equipping at any time

gripping 1 existing.

  In the exemplary embodiment, the base receiver 13 is shaped as a U-shaped component and is positioned laterally on the support 5 of gripping jaws so that it sinks completely into the U-shaped recess and that it is flanked, on opposite sides, by an arm 17 of the U-shaped base receiver 13 respectively. The fixing is carried out by means of one or more fixing screws 18, which are screwed into the support 5 gripping jaws, through the base bar 22 of the base receiver 13 which connects the

arm 17.

  It would also be possible that, thanks to an adapted shape of the support 5 for gripping jaws, the base receiver 13 forms only one piece with it. On the base receiver 13 are provided two receiving surfaces 23, 24, flat and oriented in opposite directions, which are oriented transversely and, in particular, perpendicular to the gripping direction 8, the normal to their surface being perpendicular to the direction gripping 8. In the embodiment, they are located at the outer faces of the arms 17. Each extends from the area of the front face 16 towards the rear face 25, closer to the housing 6, of the base receiver 13. In addition, two bearing surfaces 26, 27, also oriented in opposite directions, are present on the base receiver 13. They are perpendicular to the receiving surfaces 23, 24, the first surface d 'support 26, in the embodiment, located on the outer face of the base bar 22 and the second support surface 27 being constituted by the faces

  front, opposite the base bar 22, arms 17.

  The first bearing surface 26 is oriented in the release direction 9, the second bearing surface 27 is oriented in the gripping direction 8. Each bearing surface 26, 27 advantageously extends in a

  plane perpendicular to the gripping direction 8.

  As illustrated in particular in FIGS. 4 to 6, the first receiving surface 23 is located between a front retaining projection 28, associated with the front face 16, and a rear retaining projection 29 located, in the nesting direction 15, at distance from the front projection, in the region of the rear face 25 of the base receiver 13. The two retaining projections 28, 29 project from the first receiving surface 23, which forms a retaining recess 32 which is delimited, at the bottom , by the first receiving surface 23 and, in the front and rear areas, respectively by one of the holding projections 28, 29. The first receiving surface 23 preferably extends in a planar manner, and it extends in the nesting direction 15 and in the gripping direction 8. The front holding projection 28 is advantageously located directly on the front face 16 of the

basic receiver 13.

  The second receiving surface 24, located on the opposite side of the base receiver 13, oriented opposite the first receiving surface 23, extends, in the embodiment, obliquely over its entire length. In this case, the orientation is chosen so that the distance between the two receiving surfaces 23, 24 increases, from the front zone to the rear face 25, and the second receiving surface 24, seen in the nesting direction 15, therefore moves away from the

first receiving surface 23.

  In the area of the front face 16, the second receiving surface 24 is not limited. It immediately follows the front face 33, associated with the front face 16, of the base receiver 13. Conversely, in the rear zone, the second receiving surface 24 is delimited by a projection forming a stop 34 which, relative to to the nesting direction 15, is advantageously at the same height as the projection of

rear support 29.

  In the exemplary embodiment, the projections 28, 29, 34 have a shape similar to ribs and each extend over the entire width of the associated receiving surface 23, 24, measured perpendicular to the direction of interlocking. 15. But each could also be formed by several projections

  isolated, placed next to each other.

  The coupling shoe 14 already mentioned advantageously has a shape similar to a frame and comprises, in the embodiment, four branches of

  frame 35, 35 ', 36, 36' joined together perpendicularly.

  In the embodiment, one of the frame branches 36 ′ is directly formed by a section, similar to a plate, of the associated gripping jaw 4, which

  thus contributes to constituting the mating shoe 14.

  The three remaining frame branches 35, 35 ′, 36 form part, in the embodiment, of a stirrup part 37 in the form of a U which, to constitute the frame type structure, is applied to the jaw of gripping 4 and is fixedly connected to it, for example by means of screws 38. However, it will be understood that the coupling shoe 14 and the gripping jaw 4 can also form a single piece, just as it is also possible that the entire coupling shoe 14 constitutes an independent component, on which a gripping jaw 4 is capable of being fixed,

  preferably interchangeably.

  The coupling shoe 14 of the frame type delimits an opening 42 advantageously through which the

  section, in the example of execution, is rectangular.

  During assembly, the coupling shoe 14 is fitted, approximately in the nesting direction 15, on the base receiver 13 which, in this case, enters the opening 42. If the coupling shoe 14 is mounted fixedly on the base receiver 13, the coupling position shown in FIG. 7 is obtained, in which the base receiver 13 passes through the opening 42 and projects, by its front face 16, from the rear face 45, facing away from the direction

  socket 15, coupling shoe 14.

  In the coupling position shown in Figures 3 to 7, the frame branches 35, 35 ', which are

  opposite the receiving surfaces 23, 24 and which are

  after designated as first and second coupling branches 43, 44, cooperate with the receiving surfaces 23, 24 which are associated with them. The other two frame branches 36, 36 ', which extend transversely between the two coupling branches 43, 44 and are therefore designated as transverse branches 46, 46', cooperate simultaneously with the bearing surfaces

26, 27.

  Thus are provided, on the inner faces, oriented in the direction of the opening 42, transverse branches 46, 46 ', counter-abutment surfaces 47, 47', the distance of which corresponds to the distance between the two surfaces support 26, 27, so that, in the nested coupling position, the two counter-abutment surfaces 47, 47 ', each rest on an associated receiving surface 26, 27 and that the coupling shoe 14, therefore, is held on the base receiver 13, without being able to move, due to the complementarity of shapes, in the gripping direction 8. The forces which act on the gripping jaw 4 during gripping are thus transmitted , by means of the contiguous counter-abutment and support surfaces, in the support of the gripping jaw, without the gripping jaw 4 having the possibility of effecting an undesirable movement in the gripping direction 8

  or in the direction of release 9.

  The section, oriented in the direction of the opening 42, of the first coupling branch 43, constitutes a coupling part 48, the width of which, measured in the direction of fitting, corresponds to the width of the recess of holding 32, measured correspondingly, and which, in the coupling position according to FIG. 7, enters with a positive engagement in the holding recess 32. This part 48 rests, on one side, on the first receiving surface 23 and, on the other, on the delimiting surfaces 52, facing each other, of the two retaining projections 28, 29. Owing to the cooperation with the retaining projections 28, 29, one obtains, in the direction the axis 53 of the support 5 of the gripping jaw, which is parallel to the fitting direction 15, a fixed attachment of the shoe

coupling 14.

  In the coupling position, the second coupling branch 44, associated with the second receiving surface 24, is applied simultaneously to the delimiting surface 54, oriented towards the front, of the projection forming a stop 34. This position is held by a pressing element 55, subjected to the action of a spring, which is mounted on the second coupling branch 44 and which acts, under preload, on a front zone of the second oblique receiving surface 24, located near of the front face 16. The irremovable fixing of the coupling shoe 14, in the transverse direction 56 perpendicular to the first receiving surface 23, is obtained by the fact that the width, measured in this transverse direction 56, of the opening 42 , corresponds, in the region of the front face 57, oriented in the nesting direction, of the coupling shoe 14, to the transverse distance of the two receiving surfaces 23, 24 in the region of the rear face 25 d u base receiver 13. On its inner face, oriented towards the second receiving surface 24, the second coupling branch 44 is designed so that, in the coupling position shown in FIG. 7, an intermediate space 58, widening in the direction of the front face 16 of the base receiver 13, exists between the second coupling branch and the second receiving surface 24. In the embodiment, the interior surface 62, oriented in the direction of the second receiving surface 24 of the second coupling branch 44 is parallel to the first receiving surface 23, so that the intermediate space 58 has a wedge shape and decreases in the direction of fitting 15. In the coupling position, the second coupling branch 44 thus only applies by a section 63 of internal surface 62, immediately following the projection

  forming a stop 34, on the second receiving surface 24.

  The coupling shoe 14, which is in the coupling position, is removed from the base receiver 13 by first pivoting the coupling shoe 14, overcoming the pushing force F of the pressing element 55 , in the direction of arrow 64, in an inclined position illustrated in FIG. 8, the width of the intermediate space 58 thus decreasing until finally the second coupling branch 44 comes into contact, by its surface interior 62, with the second inclined receiving surface 24. The pivot axis is located approximately in the region of the rear retaining projection 29, on which the first coupling branch 43 can still be applied, also in the inclined position. However, the pivoting or tilting has the consequence that the rear end section 65, oriented opposite the fitting direction 15, of the coupling part 48 does not cooperate with the holding recess 32. Then, the coupling shoe 14 can be removed from the base receiver 13 by applying a traction force Z. When it comes to be placed in the inclined position, the pressing element 55 is depressed, against the elastic force which acts on him. In the embodiment, this element is shaped like a cleat and is housed, with the possibility of sliding, in a recess 66 in the second coupling branch 44,

  which is open towards its inner surface 62.

  A compression spring 67, also housed in the recess 6 constantly urges the pressing element, in the direction of an exit from the recess 66. In this case, when the coupling shoe 14 is removed, as in FIG. 4, the pressing element 55 comes to be placed in a basic position in which it protrudes from the internal surface 62 by a thrust part 68, and enters the opening 42. Thanks to stop-forming means provided at the inside the recess 66, the pressing element 55 cannot be released any more. The pushing part 68 provided on the front end zone advantageously has a shape which corresponds to a section

of a spherical surface.

  In order to have a compact assembly, the pressing element 55 may have a recess 72 in which the

  compression spring 67 can penetrate.

  It would also be possible to provide several pressing elements in place of a single pressing element 55. In addition, it would be possible to use thrust elements of different conformation, for example sphere-shaped elements. In addition, the spring effect could be provided by a component forming part

  integral with the pressing element 55.

  The mounting of the coupling shoe 14 on the base receiver 13 could, in principle, be carried out in the same way as its removal, described above. However, it would be necessary, in this case, to apply a considerable force, to push the pressing element against the elastic force which is applied to it. Consequently, in the exemplary embodiment, a device is provided which reduces the force applied during assembly, a device which will now be the subject of a

description.

  This device comprises a recess 73, provided on the inner face, oriented in the direction of the first receiving surface 23, of the coupling part 48, namely advantageously at least approximately at the same height as the pressing element 55, with respect to to the direction of the axis 53. A particularly advantageous form of recess 73 is shown in FIGS. 4 to 8, according to which the recess 73, on its rear face oriented opposite the direction of fitting 15, has a concave rounded wall trace 74. In the direction of the front face 57, the depth of the recess 73 progressively decreases, the recess 73 not fully extending to the rear end of the coupling part 48. Thus, the recess 73 is located between a first bearing surface 75, placed upstream, in the direction opposite to the direction of fitting 15, and a second bearing surface 76, following it in the direction of fitting 15, the two bearing surfaces 75, 76, in the coupling position of the coupling shoe 14, resting on the first receiving surface 23. In the front zone, oriented in the direction of nesting 15, between the two coupling branches 43, 44, the opening 42 has a width determined by the distance between the surface section 63 and the second bearing surface 76, a width which corresponds to the distance between the associated end sections of the receiving surfaces 23, 24. There is the same width between the front zone of the second receiving surface 24 and the outer surface 77, oriented opposite this zone, of the projection of

hold before 28.

  During assembly, the coupling shoe 14 is first of all fitted onto the base receiver 13, in accordance with FIG. 4, in the direction of fitting 15. In this case, a slight inclination of the coupling shoe 14 facilitates initial threading on

the base receiver 13.

  Then, the coupling shoe 14 is fitted on the base receiver 13 until the pressing element 55, by its pushing part 68, comes to bear on the front face 33. The front holding projection 28 is however able to penetrate into the recess 66, which causes a transverse displacement of the coupling shoe 14, in the direction of the arrow 78, which has the consequence that the pressing element 55, by its thrust part 68 , arrives, passing on the front face 33 of the base receiver 13, in the initial zone of the second receiving surface 24. A suitable break in the transition edge can further aid this process. The corresponding assembly phase is shown in the

figure 5.

  From this position, the coupling shoe 14 can be pivoted into an inclined position, in the direction of the arrow 79 in FIG. 6, a position which is comparable to that which is shown in FIG. 8 differentiates only by a shorter nesting path with respect to the base receiver 13. In all cases, during tilting, the pressing element 55 which rests on the second receiving surface 24 is moved with a force reduced, the first coupling branch 43 simultaneously adopting a position in which the first bearing surface 75 which is provided on it can slide on the outer surface 77 of the front retaining projection 28, when the coupling shoe 14, as a next element, is completely fitted, in the fitting direction, on the base receiver 13. As soon as the coupling part 48, through its first bearing surface 75, has passed along the projection holding before 28, the coupling shoe 14 again leaves the inclined position, following its request by the pressing element, and comes to occupy the coupling position

shown in Figure 7.

Claims (15)

Claims   1. Coupling device intended to make the detachable coupling of a gripping jaw (4), having a gripping part (7), with the support (5) of gripping jaw of a gripping device (1 ) capable of being used for handling objects (3), comprising a base receiver (13) provided or capable of being mounted on the support (5) of the gripping jaw, and comprising a coupling shoe (14) provided or capable of being mounted on the gripping jaw (4), which is capable of being fitted, from a front face (16), in a fitting direction (15), on the base receiver (13), two receiving surfaces (23, 24), turned in opposite directions and oriented perpendicular to the gripping direction (8), being provided on the base receiver (13) and the coupling shoe (14) having two coupling branches (43, 44) facing each other with a gap in which it covers the two receiving surfaces (23, 24), in the nested coupling position, characterized in that the first receiving surface (23) is situated between a front retaining projection (28) and a rear retaining projection (29), showing a certain distance, in the nesting direction (15), relative to the latter, the first receiving surface (23) and the two holding projections (28, 29) delimiting a holding recess ( 32), in which the associated coupling branch (43) engages by complementarity of shapes, in the coupling position, by a coupling part (48) having the same width, in the nesting direction ( 15), in that the second opposite receiving surface (24) extends obliquely and has, in the front region, a distance from the first receiving surface (23) which is smaller than in the rear part, this surface being delimited, in the rear area re, by a projection forming a stop (34) on which rests, in the coupling position, the second coupling branch (44) associated with the coupling shoe (14), an intermediate space (58), going widening towards the front face of the second receiving surface (24), existing simultaneously between the second coupling branch (44) and the second oblique receiving surface (24), intermediate space which allows the coupling shoe (14) to pivot, with respect to the base receiver (13), in an inclined position, in which the rear end section (65), oriented opposite the direction of fitting (15), of the part d coupling (48) of the first coupling branch (43) does not cooperate with the holding recess (32), and in what is provided, on the second coupling branch (44), at least one pressing element (55), subjected to the action of a spring, which, in the coupling position, acts on a z one before the second oblique receiving surface (24) opposite, crossing the intermediate space (58), and thus supports the second coupling branch (44) against the projection forming a stop (34), the coupling shoe ( 14) can be pivoted in the inclined position by overcoming the element's pushing force presser (55).   2. Coupling device according to claim 1, characterized in that the coupling part (48), provided on the first coupling branch (43), has, on its inner face, oriented towards the first surface receiving (23), approximately at the same height as the pressing element (55) provided on the second coupling branch (44), a recess (73) which, when the coupling shoe (14) is fitted, allows the front retaining projection (28) to sink in order to simultaneously position the pressing element (55) on the front zone of the second oblique receiving surface (24), passing over the front face (33) from the base receiver part (13)   which has the second receiving surface (24).   3. Coupling device according to claim 2, characterized in that the recess (73) has, on its rear face oriented opposite the nesting direction (15), a wall trace (74) concave rounded.   4. Coupling device according to claim 3, characterized in that the depth of the recess (73) decreases progressively in the nesting direction (15).   5. Coupling device according to one of   Claims 2 to 4, characterized in that the recess   (73) is located between a first bearing surface (75) placed upstream, in the direction opposite to the nesting direction (15), and a second bearing surface (76), following it in the direction nesting (15), the two bearing surfaces (75, 76), in the coupling position of the coupling shoe (14), applying to the first receiving surface (23) inside the retaining recess (32).   6. Coupling device according to one of   Claims 1 to 5, characterized in that the opening   (42) delimited by the coupling branches (43, 44), in the front zone oriented in the nesting direction (15), has a width which corresponds to the distance from the two receiving surfaces (23, 24), in the area of the rear retaining projection (29) and the projection forming a stop (34).   7. Coupling device according to one of   Claims 1 to 6, characterized in that the surfaces   receptors (23, 24) are shaped into flat surfaces.   8. Coupling device according to one of   Claims 1 to 7, characterized in that the pressing element (55) is shaped as a body capable of being   move in a recess (66) of the second coupling branch (44), body which is subjected to the action of a compression spring (67).   9. Coupling device according to one of   claims 1 to 8, characterized in that the element   presser (55), in its front end zone oriented towards the second receiving surface (24), has   a shape similar to a spherical surface.   10. Coupling device according to one of   Claims 1 to 9, characterized in that the shoe   coupling (14) has a frame-like shape, the two coupling branches (43, 44) being constituted   by opposite frame branches (35, 35 ').   11. Coupling device according to claim 10, characterized in that the through opening (42) which is delimited by the coupling shoe (14) of the frame type has a section transverse rectangular.   12. Coupling device according to claim 10 or 11, characterized in that the coupling shoe (14) consists of a section of a gripping jaw (4) and by a part forming   U-shaped stirrup (37) formed thereon.   13. Coupling device according to one of   claims 1 to 12, characterized in that,   on the base receiver (13), bearing surfaces (26, 27), oriented opposite each other, extending perpendicular to the receiving surfaces, on which the coupling shoe (14 ) is applied by counter-abutment surfaces (47, 47 ') in the coupling position. 14. Coupling device according to claim 13, characterized in that the counter-abutment surfaces (47, 47 ') are provided on the inner faces of the two transverse branches (46, 46'), extending between the branches of coupling (43, 44), of the coupling shoe (14) of the frame type. 15. Coupling device according to one of   claims 1 to 14, characterized in that the receiver   base (13) is a component detachably attached to the support (5) of the gripping jaw.