EP0420753A1 - Device for fastening a holding part on lenses - Google Patents

Abstract

The invention relates to a device for fastening a holding part on lenses, of the type comprising, for placing a gripping block (12) onto a spectacle lens (10) waiting on a stage (11), a holding arm (16), designed for receiving the gripping block (12) removably, and a carriage (20), on which the holding arm (16) is mounted pivotably between two positions and which is itself mounted movably between two positions along a path in the course of which the holding arm (16) is presented automatically in line with the stage (11). <??>According to the invention, since the carriage (20) is at least partially mounted movably in a straight line in a first direction (D1), the pivot axis (34) of the holding arm (16) extends in a second direction (D2) orthogonal to the first, and between this carriage (20) and this holding arm (16) is inserted a transmission (30) capable of causing the holding arm (16) to change from one of its positions to the other when the carriage (20) changes itself from one of its positions to the other. <??>The invention is used especially in centring devices. <IMAGE>

Description

The present invention relates generally to the fitting, on a lens of glasses to work, and for example to overflow, of a block, said here for simple convenience gripping block, which, adapted to not adhere to such spectacle lens that temporarily, for example by means of a suction cup, is intended to allow it to be put in place, and locked in position, on a machine suitable for the work to be performed.

The corresponding gluing devices fall, for example, within the framework of the centering devices used beforehand for locating either the geometrical center of the spectacle lens to be treated or its optical center, the gripping block concerned then having to be arranged in a location determined in relation to one or other of these centers.

They comprise, in practice, a sliding arm, which is adapted to receive in a removable manner, the gripping block to be placed, and a carriage, on which the sliding arm is pivotally mounted between two extreme positions, one for loading and unloading, the other laying, and which, carried by a frame, is itself mounted mobile between two extreme positions, one of rest, the other of racing fih, on this frame, following a path during which the gloving arm which it carries presents itself, in the installation position, in line with a plate on which is placed in standby the spectacle lens to be treated.

This is the case, for example, in US Patent No. 4,543,752.

According to this American patent, the control of the carriage carrying the sliding arm can either be carried out manually or be motorized.

However, in both cases, the sliding arm is pivotally mounted in the same direction as that in which the carriage moves, with a screw-nut type engagement between it and the latter.

Such a type of meshing inevitably generates significant friction, to the detriment of its efficiency.

The present invention generally relates to a provision which, also capable of manual or motorized control, is advantageously free from this drawback.

More specifically, it relates to a sliding device of the type comprising, for the installation of a gripping block on a spectacle lens arranged in standby on a plate, a sliding arm, which is adapted to receive, removably, the gripping block to be placed, and a carriage, on which this sliding arm is pivotally mounted between two extreme positions, one for loading and unloading, the other for laying, and which, carried by a frame , is itself mounted movable between two extreme positions, one at rest, the other at the end of the race, on this frame, along a path during which the gloving arm which it carries presents itself , in the installation position, in line with said plate, and which is characterized, in general, in that, the carriage being at least partly mounted movable in a rectilinear manner, in a first direction, under the control of a guide integral with the frame, and the pivot axis of the gla arm ntage extending in a second direction, orthogonal to the previous one, it intervenes, between said carriage and said sliding arm, for the passage of the sliding arm from one of its positions to the other, a belt transmission (s ) and gables.

For example, this transmission comprises, locked in rotation with each other by at least one belt, a rotary pinion on which is fixed in rotation the pivot axis of the gliding arm, at least one rotary pinion carried by the carriage, and at least one rotary pinion fixed relative to the frame.

In any case, it is with the same movement that the carriage passes from one of its positions to the other and that, jointly, the sliding arm itself passes from one of its positions to the 'other, and the corresponding movements are advantageously performed with excellent efficiency.

Admittedly, it is known from document FR-A-2,608,492, of which the Applicant is at the origin, a sliding device in which the sliding arm is pivotally mounted on a block which is itself movably mounted so straight like a carriage.

However, in this document, there is no transmission between this sliding arm and this carriage, within the meaning of the present invention, and, a fortiori, no transmission with belt (s) and pinions, the passage of the sliding arm from one of its positions to the other, as well as that of the block which carries it, being carried out under the control of cam means carried by another block mounted mobile in synchronism with the previous one but in the opposite direction to this one.

They are therefore, in both cases, slipping devices of very different configurations.

• la figure 1 est, avec des arrachements locaux, une vue en perspective d'un dispositif de glantage suivant l'invention ;
• la figure 2 est un bloc diagramme qui, reprenant, en perspective, ce dispositif de glantage, illustre la commande qui est la sienne ;
• les figures 3A, 3B, 3C, 3D sont des vues schématiques, en élévation, de ce dispositif de glantage, pour diverses phases successives de son intervention ;
• la figure 4 est un bloc diagramme qui, reprenant pour partie celui de la figure 2, se rapporte à une variante de réalisation ;
• la figure 5 est un bloc diagramme se rapportant à une autre variante de réalisation, représentée en élévation, pour la position de chargement et de déchargement du bras de glantage correspondant ;
• la figure 6 est, à échelle différente, une vue en élévation de cette variante de réalisation, pour la position de pose du bras de glantage ;
• la figure 7 en est une vue partielle arrière, suivant la flèche VII de la figure 6 ;
• la figure 8 en est une vue partielle en coupe transversale, suivant la ligne brisée VIII-VIII de la figure 6.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which:

• Figure 1 is, with local cutaway, a perspective view of a gliding device according to the invention;
• FIG. 2 is a block diagram which, taking up, in perspective, this gliding device, illustrates the control which is its own;
• FIGS. 3A, 3B, 3C, 3D are schematic views, in elevation, of this gliding device, for various successive phases of its intervention;
• Figure 4 is a block diagram which, partly taking that of Figure 2, relates to an alternative embodiment;
• Figure 5 is a block diagram relating to another alternative embodiment, shown in elevation, for the loading and unloading position of the corresponding gluing arm;
• Figure 6 is, on a different scale, an elevational view of this alternative embodiment, for the installation position of the gloving arm;
• Figure 7 is a partial rear view, along arrow VII of Figure 6;
• FIG. 8 is a partial view in cross section thereof, along the broken line VIII-VIII of FIG. 6.

As illustrated in these figures, it is a question, overall, of attaching, on a spectacle lens 10 disposed in standby on a plate 11, a gripping block 12 comprising, for example, for this purpose, a suction cup 13.

In the embodiment shown in Figures 1 to 4, the gliding device 15 used to do this generally comprises a gliding arm 16, which is adapted, by a receptacle 17 which it has front for this purpose, to receive, removably, by tightening a screw 18, the gripping block 12 to be placed, and a carriage 20, on which this gliding arm 16 is pivotally mounted between two extreme positions; one for loading and unloading, shown in solid lines in FIG. 1, the other for laying, shown in broken lines in this FIG. 1, and which, carried by a frame 21, of which only a few elements are, that and there, shown, partially, in Figure 1, is itself mounted movable between two extreme positions, one of rest, which is that of Figure 1, the other end of travel, on this frame 21, according a path during which, as will appear in more detail later, the sliding arm 16 which it carries presents itself, in the installation position, in line with the plate 11.

This plate 11 may belong to the gliding device 15.

It can also belong to the device, centering device or other, that such a gliding device 15 is intended to equip.

This is the reason why, like the spectacle lens 10 and the gripping block 12, it has only been shown in broken lines in FIG. 1.

Anyway, this plate 11 is fixed relative to the frame 21.

In the embodiment shown in FIGS. 1 to 4, the carriage 20 has a general configuration in a gallows, in a single part, with a vertical portion 22, and, in cantilever with respect thereto, a horizontal portion 23.

Since this carriage 20 does not in itself fall within the scope of the present invention, it will not be described in more detail here.

It will suffice to indicate that, under the control of a guide 24, which is integral with the frame 21, and with which it is engaged by rotary rollers 25, it is movable in a rectilinear manner in a first direction D1, in practice a vertical direction, perpendicular to the plate 11, that it has a stop 29 against which bears the sliding arm 16 in the installation position, and that, for reasons which will appear later, the end 26, or nose, of its horizontal portion 23 is, preferably, and as shown, in the form of a yoke.

The frame 21 also does not fall, per se, of the present invention, nor will it be described in detail here.

It suffices to indicate that, for the delimitation of the maximum stroke of the carriage 20, it carries, projecting, on the one hand, a high stop 27, and, on the other hand, a low stop 28.

According to the invention, the pivoting axis of the sliding arm 16 extends in a second direction D2, orthogonal to the previous direction D1, and, between this carriage 20 and this sliding arm 16, there is a belt transmission 30 (s) and pinions suitable for making pass the gloving arm 16 from one of its positions to the other.

In the embodiment shown, the gloving arm 16 is in the form of a stirrup, with a central part 31, which carries the receptacle 17, and two lateral arms 32, by which it is articulated to the nose 26 of the carriage 20.

In the loading and unloading position, FIGS. 1, 2 and 3A, it therefore delimits, with the yoke that constitutes the nose 26 of the carriage 20, a recess 33, suitable for implementing lighting for the plate 11 if longed for.

Jointly, in this embodiment, its pivot axis is formed by two pins 34, which are integral, each respectively, with its two arms 32, and only one of which is visible in FIG. 1.

In what follows, the pivot axis of the gloving arm 16 will also be designated by the reference 34.

For example, and as shown, the transmission 30 comprises, locked in rotation with each other by at least one belt 36, and all rotating, a pinion 37 on which is pivotally locked the pivot axis 34 of the arm of glantage 16, at least one pinion 38, which is carried by the carriage 20, and at least one pinion 39, which is fixed relative to the frame 21.

In the embodiment more particularly shown in FIGS. 1 to 3, one and the same belt 36 is used, on one of the sides of the carriage 20, and this passes in endless loop on the pinion 37, on two pinions 38, which, carried by the carriage 20, are arranged, each respectively, on either side of the preceding pinion 37, and on two pinions 39 which, fixed relative to the frame 21, are arranged, each respectively, on either side of the carriage 20, one on the side of the upper stop 27 defining one of its extreme positions, the other on the side of the lower stop 28 defining the other of these.

In practice, in the embodiment shown, there is an additional rotary pinion 39 on the frame 21.

While the belt 36 passes through its internal face on the pinion 37 and the pinions 39, it passes through its external face on the pinions 38, and it is preferably a toothed belt.

The two pinions 38 carried by the carriage 20 are substantially disposed opposite one another, at a distance from the pinion 37 on which the pivot axis 34 of the gluing arm 16 is wedged.

Similarly, apart from a slight offset caught up by the additional pinion 39, the latter being in practice substantially vertical to the pinion 39 disposed on the side of the bottom stop 28, the pinions 39 carried by the frame 21 on the side of the upper stop 27 and on the side of the lower stop 28 extend substantially along the same level, behind the pinions 38 above.

Thus the belt 36 generally forms two loops, one substantially vertical, the other substantially horizontal, between the ends of the previous one.

In the embodiment shown, at least one of the pinions 37, 38, 39 is fixed on the output shaft 40 of a motor 41, via, optionally, and as shown, a reduction gear 42.

It is, in practice, a pinion 39 fixed relative to the frame 21, and, more precisely, in the embodiment shown, that arranged on the side of the bottom stop 28.

In practice, also, the motor 41, which is carried by the frame 21, is an electric motor, and, in the loading and unloading position, the sliding arm 16 intervenes, by one of its arms 32, on a limit switch 44, of the microswitch type for example, which is also carried by the frame 21, and to which the power supply for this electric motor 41 is controlled.

As shown diagrammatically in the block diagram of FIG. 2, the supply of the electric motor 41 is under the control of a control block 45, itself under the control, on the one hand, of the limit switch 44 and other part, a control push button 46 available to the practitioner.

Since the control block 45 does not fall within the scope of the present invention, it will not be described here.

In addition to the control means that constitute in its regard, under the dependence of the electric motor 41, the transmission 30, the carriage 20 is subjected to elastic return means 48 which urge it permanently in the direction of its rest position, it that is to say in the direction of the upper stop 27.

In the embodiment shown, these elastic return means 48 are constituted by a tension spring coupled, on the one hand, by a stud 49, to the carriage 20, and, on the other hand, by a stud 50, to the frame 21.

Preferably, the elastic return means 48 thus formed are chosen so that the stress which results therefrom on the carriage 20, when it moves in the direction of its rest position, is sufficient to maintain the sliding arm 16 in bearing against the stop 29 provided for him on this carriage 20, and, therefore, in order to then maintain in position the laying arm 16.

At the start of a work cycle, the carriage 20 is in the high rest position, pressing against the high stop 27, under the stress of its elastic return means 48, and, jointly, the gluing arm 16 is in the position deployed loading and unloading for which it intervenes on the limit switch 44, Figures 1, 2 and 3A.

For this deployed loading and unloading position, which is horizontal, the sliding arm 16 advantageously has the receptacle 17 at the front, which facilitates the positioning, in the latter, of the gripping block 12 to be placed.

After the glasses 10 to be fitted have been placed on the plate 11 and the position thereof has been checked on this plate 11, for example by the recess 33 which then delimits the sliding arm 16 with the nose 26 of the carriage 20, the practitioner intervenes on the control push button 46, which triggers the entry into action of the electric motor 41, and, therefore, the drive, according to arrow F1 in FIG. 3A, of the belt 36.

Initially, and taking into account the only elastic stress which is the object of the carriage 20 due to the spring 48, this carriage 20 remains pressed against the upper stop 27, and the drive, according to arrow F1, of the belt 36, has the sole effect of pivoting, along arrow F2 of FIGS. 3A and 3B, the sliding arm 16, the latter passing from its previous loading and unloading position to the laying position for which it is in abutment against the stop 29 provided for this purpose on this carriage 20, FIG. 3B.

In doing so, the gloving arm 16 abandons the limit switch 44.

However, in the control unit 45, a relay is provided which cancels the inversion effect which could result on the direction of supply of the electric motor 41, and therefore on its direction of rotation.

In a second step, the drive, along arrow F1, of the belt 36, which continues, in turn causes the drive, according to arrow F3, of FIG. 3B, of the carriage 20.

This carriage 20 therefore abandons the upper stop 27, and goes towards the lower stop 28, by pulling on the spring constituting its elastic return means 48.

However, during its journey, the gripping block 12 carried by the gloving arm 16 is applied, as desired, on the spectacle lens 10 present on the plate 11, FIG. 3C.

Because of the resistance which results therefrom, and by the intervention of means which, not falling within the scope of the present invention, will not be described here, a new reversal of the relay which comprises the control block 45 causes a change in rotation of the electric motor 41.

In the absence of spectacle lens 10 on the plate 11, the carriage 20 comes to bear against the bottom stop 28, consequently causing the same change in rotation for the electric motor 41.

As soon as this change in rotation occurs, the elastic return means 48 of the carriage 20 ensure, along the arrow F′3 in FIG. 3D, the drive, of return, of this carriage 20, in the direction of the upper stop 27.

However, due to the action of these elastic return means 48, the sliding arm 16, which, by the gripping block 12, then carries with it the spectacle lens 10, advantageously remains in the laying position, in abutment against the stop 29 of the carriage 20.

The volume swept by the spectacle lens 10 is thus limited, which makes it easier to disengage from the plate 11, without risk of interference with the latter or with other members possibly present in the vicinity of this plate 11.

6th is only when the carriage 20 is again in abutment against the upper stop 27 that the belt 36, duly driven by the electric motor 41, ensures the return, in the loading and unloading position, of the sliding arm 16, according to the initial configuration of the assembly shown in Figure 3A.

When it returns to the loading and unloading position, the sliding arm 16 again intervenes on the limit switch 44, which stops the supply of the electric motor 41.

It then suffices for the practitioner to remove from the gloving arm 16 the spectacle lens 10 duly provided with its gripping block 12.

According to the variant embodiment illustrated in FIG. 4, the transmission 30 comprises two belts, namely, on the one hand, a first belt 36 ′, which is passed in endless loop on the pinion 37 on which the axis is wedged pivoting 34 of the sliding arm 16 and on a pinion 38 carried by the carriage 20, and, on the other hand, a second belt 36˝, which is passed in an endless loop on a pinion 38˝ fixed in rotation on the preceding pinion 38, a pinion 39, which, fixed relative to the frame 21, is wedged on the output shaft 40 of the electric motor 41, and a return pinion 39, which, also globally fixed with respect to the frame 21, is for example however mounted oscillating relative to the latter to ensure a suitable tension for the belt 36˝ whatever the carriage position 20.

For the rest, the provisions are of the type described above, and it is the same for the operation of the assembly.

In the above, the carriage 20 is in one part.

In the alternative embodiment illustrated in FIGS. 5 to 8, it is in two parts, namely a part 20 ′, which, forming a slide, is mounted movable in a rectilinear manner on the frame 21, in the direction D1 perpendicular to the plate 11 associated, which is not shown in FIGS. 5 and 8, and a part 20˝, which, forming a crank, meshes with a hinge 55 with the part 20 ′ above, and is pivotally mounted on the frame 21 according to a third direction D3 parallel to the direction D2 along which the pivot axis 34 of the sliding arm 16 extends.

In practice, the direction D1 in which the part 20 ′ forming a slide is mounted to be movable in a rectilinear manner and the direction D2 in which the pivot axis 34 of the gliding arm 16 extends are coplanar.

It follows that, during the application of a suction cup 13 to the spectacle lens 10 to be fitted, the direction in which the corresponding application force develops is advantageously confused with the direction D1 according to which the carriage 20 is guided .

The operating conditions and installation of the suction cup 13 are improved.

In the embodiment shown, the part 20 ′ forming the slide of the carriage 20 has two bars parallel 56, which, each arranged respectively on either side of the frame 21, are each respectively engaged with two grooves 57 formed on the sides of this frame 21, outside of the latter.

In practice, this part 20 ′ forming the slide of the carriage 20 is reduced even to these two bars 56, and these are each respectively in engagement with the pins 34 specific to the constitution of the pivot axis of the sliding arm 16.

As before, this gliding arm 16 is in the form of a stirrup, with a central part 31, having the receptacle 17 suitable for the installation of the suction cup 13 to be placed, and two lateral arms 32.

Jointly, the part 20˝ forming the crank of the carriage 20 comprises, in this embodiment, two parallel rods 59, which, articulated, by pins 60, on the frame 21, in the direction D3, extend laterally between the lateral arms 32 of the sliding arm 16 and the bars 56 constituting the part 20 ′ forming associated slide.

For each of these links 59, the clearance articulation 55 comprises a buttonhole 61, which is elongated radially, and by which it is engaged, without circumferential clearance, on the corresponding pin 34.

In the embodiment shown, the pins 34 are carried by the lateral arms 32 of the gliding arm 16.

However, as a variant, they could as well be carried by the bars 56.

In the embodiment shown, the associated transmission 30 comprises, parallel to one another, two belts 36, which intervene, each respectively, on one and the other of the sides of the carriage 20, and therefore of the frame 21.

As before, each of these belts 36 has passed, in an endless loop, over a pinion 37, on which the pivoting axis 34 of the gluing arm is rotated. 16, two pinions 38, which are rotatably mounted on the carriage 20, and two pinions 39 carried by the frame 21.

However, in the embodiment shown, the corresponding pinions 37 are in one piece with the lateral arms 32 of the gluing arm 16, and the pinions 38 carried by the carriage 20 are in fact rotatably carried by the 20˝ part forming a crank of it.

In addition, in the embodiment shown, there is provided, as before, for each belt 36, an additional pinion 39, which, carried by the frame 21, forms a tensioner, this additional pinion 39 being rotatably mounted on a lever 63 which , pivotally mounted on the frame 21, is subjected to elastic means, constituted for example by a simple spring 64, leading it to be applied, from the outside, on the corresponding belt 36, on the external face of the latter , to swallow the slack of this belt 36 during the movement of the carriage 20.

As a corollary, in the embodiment shown, those of the pinions 39 carried by the frame 21 which are arranged on the side of the upper stop 27 of the carriage 20 not shown in the figures are rotatably mounted on a bracket 67 whose support on the frame 21 is capable of being adjusted by screws 68; it is thus advantageously possible to ensure a suitable initial tensioning of the belt 36.

The other pinions 39 carried by the frame 21, on the side of the bottom stop 28 of the carriage 20, are jointly wedged, as before, on the output shaft 40 of a geared motor 41, 42.

Finally, in this embodiment, the recess formed between them by the sliding arm 16 and the carriage is effectively used for lighting the plate 11 on which must be placed the spectacle lens 10 to be fitted.

To this end, a support 69 is provided in the frame 21, on which is attached a lamp 70, a mirror 72, and a condenser 73.

For the rest, the arrangements are of the type described above, in particular as regards the elastic return means permanently urging the carriage 20 towards its high rest position, and as regards the stop provided on the carriage 20 for the sliding arm 16.

The operation of this variant embodiment is therefore also of the same type as the previous one: when the geared motor 41, 42 is put into action, there is first of all a pivoting of the sliding arm 16 from its position I, of loading and unloading, shown in solid line in Figure 5, in an intermediate position II, orthogonal to the previous one and shown schematically in broken lines in this figure 5, then the movement of this gloving arm 16 from this intermediate position II to its position pose III, shown schematically in broken lines in FIG. 5 and in solid line in FIG. 6.

In the foregoing, it is by simple convenience, for the sake of clarity of presentation, that, on the descent, the gliding arm is said to pivot before the carriage takes off from its upper stop.

In reality, the corresponding movements may be concomitant, the carriage initiating its downward movement at the same time as the gliding arm initiating its pivoting movement, and vice versa.

Moreover, according to a variant of manual embodiment, the descent of the carriage is controlled by hand, and it is its descent movement which, by the belt transmission (s) and pinions according to the invention, induces the movement of pivoting of the gluing arm.

Of course, the present invention is not limited to the embodiments described and shown, but encompasses any variant and / or combination of their various elements.

Claims (20)

1. A gliding device, of the type comprising, for the installation of a 4th gripping block (12) on a spectacle lens (10) disposed in standby on a plate (11), a gliding arm (16), which is suitable for removably receiving the gripping block (12) to be placed, and a carriage (20), on which the gliding arm (16) is pivotally mounted between two extreme positions, one for loading and unloading , the other for laying, and which, carried by a frame (21), is itself mounted mobile between two extreme positions, one at rest, the other at the end of the race, on this frame (21), along a path during which the gliding arm (16) which it carries presents itself, in the installation position, in line with said plate (11), characterized in that, the carriage (20) being at less for part mounted movable in a rectilinear manner, in a first direction (D1), under the control of a guide (24) integral with the frame (21), and the pivot axis (34) of the glanta arm ge (16) extending in a second direction (D2), orthogonal to the previous one, it intervenes, between said carriage (20) and said sliding arm (16), for the passage of the sliding arm (16) from one of its positions to the other when said carriage (20) passes itself from one of its positions to the other, a transmission (30) with belt (s) and pinions. 2. Gliding device according to claim 1, characterized in that said transmission (30) comprises, locked in rotation with each other by at least one belt (36, 36 ′, 36˝), and all rotary, a pinion (37) on which is pivoted the pivot axis (34) of the gliding arm (16), at least one pinion (38) which is carried by the carriage (20), and at least one pinion (39) which is fixed relative to the frame (21). 3. Gliding device according to claim 2, characterized in that the same belt (36) passes in an endless loop on the pinion (37) on which is pivotally locked the pivot axis (34) of the gliding arm (16), out of two pinions (38) which, carried by the carriage (20), are arranged, each respectively, on either side of the preceding, and on two pinions (39), which fixed relative to the frame (21), are arranged, each respectively, on both sides, of the carriage (20). 4. Gliding device according to claim 3, characterized in that there is an additional pinion (39) on the frame (21). 5. gliding device according to any one of claims 2 to 4, characterized in that at least one of the pinions (37, 38, 39) is wedged on the output shaft (40) of a motor ( 41). 6. gliding device according to claim 5, characterized in that the pinion wedged on the output shaft (40) of a motor (41) is a pinion (39) fixed relative to the frame (21). 7. Gliding device according to any one of claims 5, 6, characterized in that, in the loading and unloading position, the gliding arm (16) acts on a limit switch (44) to which is controlled the motor supply (41). 8. Gliding device according to any one of claims 1 to 7, characterized in that the carriage (20) has a stop (29) against which carries the gliding arm (16) in the laying position. 9. gliding device according to claims 5 and 8, taken together, characterized in that, the carriage (20) being subjected to elastic return means (48) which urge it permanently towards its rest position, said elastic return means (48) are chosen so that the resulting stress on the carriage (20) during its movement towards its rest position is sufficient to keep the gluing arm (16) in abutment the stop (29) provided for him on this carriage (20). 10. Gliding device according to any one of claims 1 to 9, characterized in that the frame (21) door stops (27, 28) for supporting the carriage in either of its extreme positions. 11. Gliding device according to any one of claims 1 to 10, characterized in that, in the loading and unloading position, the gliding arm (16) defines, with the carriage (20), a recess (33) . 12. Gliding device according to claim 11, characterized in that the gliding arm (16) is in the form of a stirrup and it is articulated to a nose (26) of the carriage (20) which is itself in the form of screed. 13. Gliding device according to any one of claims 1 to 12, characterized in that the carriage (20) is in one part. 14. Gliding device according to any one of claims 1 to 12, characterized in that the carriage (20) is in two parts, a part (20 ′), which, forming a slide, is mounted movable in a rectilinear manner according to the first direction D1, and a part (20˝), which forms a crank, meshes by a play articulation (55) with the part (20 ′) and is pivotally mounted on the frame (21) in a third parallel direction (D3) to the direction (D2) along which the pivot axis (34) of the sliding arm (16) extends. 15. gliding device according to claims 2 and 14, taken together, characterized in that the pinion (38) carried by the carriage (20) is carried by the part (20˝) forming a crank thereof. 16. Sliding device according to any one of claims 14, 15, characterized in that the direction (D1) in which the part (20 ′) forming the slide of the carriage (20) is mounted movable in a rectilinear manner and the direction ( D2) along which the pivot axis (34) of the gliding arm (16) extends are coplanar. 17. Gliding device according to any one of claims 14 to 16, characterized in that the part (20 ′) forming the slide of the carriage (20) comprises two parallel bars (56) engaged with grooves (57) of the frame (21). 18. Gliding device according to claim 17, characterized in that the part (20 ′) forming the slide of the carriage (20) is reduced to the two bars (56). 19. Gliding device according to any one of claims 14 to 18, characterized in that the part (20˝) forming the crank of the carriage (20) comprises two parallel links (59) articulated to the frame (21). 20. Gliding device according to claim 19, characterized in that the part (20˝) forming the crank of the carriage (20) is reduced to the two links (59) and each of these is engaged by a buttonhole with a pin ( 34) with which the corresponding bar (56) is engaged.

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