Device for facilitating the insertion, by a robot, of a tool into a hole of complementary shape

Agent (s): Cabinet LA de Boisse.

Device to facilitate the introduction, by a robot, of a tool into a hole of complementary shape.

FR 2 555 083 - Al (57) The invention relates to a device for facilitating machining by robot

A drill 4 is suspended from the Cardan joint, in 6-63-66, and balanced by counterweights 8, on a carriage 3, which a jack can slide on a frame, fixed to the manipulator arm of the robot; a guide member 5a of the drill 4c is pushed into a barrel c of a gauge G, so that the cardan joints 6-6a-66 allow the alignment of the axis a of the barrel c and the axis γ of 4; the drill 4c then crosses 5a and c, to drill a sheet P.

The invention is applicable to automatic machining.

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The present invention relates to a device to facilitate the introduction, by a robot, of a tool into a hole of complementary shape, for example to facilitate the introduction of the drill of a drill into a barrel of a template.

Most robots currently used in the industry have a pointing accuracy of their manipulator arm, which proves to be insufficient for precise machining jobs. If we consider for example a drilling operation using, for pointing, a template provided with a barrel whose internal diameter has a nominal value of 10 mm *, and a depth equal to 10 mm, and if the drill has an external diameter of 9.99 mm., on the one hand, the axis of the drill must be aligned with that of the barrel with an angular precision of less than 1 degree, and, on the other hand, its axis must be brought into coincidence with that of the barrel at least 0.01 mm. near. It is understandable that such a precise pointing is very difficult to obtain with the manipulator arm of a robot, which can weigh several tens of kilograms, and therefore be subjected to various mechanical stresses, in particular of bending, the variations of which depend on the ambient temperature are far from being negligible.

One of the main purposes of the present invention is to provide a device of the indicated type, which is capable of facilitating the pointing of an operation, for example, of any machining, using / a barrel of a template, so as to be able to obtain the machining precision required, without imposing excessive constraints on the precision of the movements of the manipulator arm carrying the tool.

The device according to the present invention is of the type which has just been indicated, and it is characterized in that the tool, as well as possibly its guide member, are supported by means of two Cardan joints, and practically balanced, in a tool holder, fixed itself at the end of the manipulator arm of the robot, so that the latter can approach the tool :, or its guide member, from the entrance of the hole in a direction inclined on the axis of said hole, and that means are provided for engaging the tool, or its guide member, in the hole, by pushing it towards the inside of said hole.

By virtue of these arrangements according to the present invention, the manipulator arm can approach the tool at the entrance to the hole, for example at the entrance to the barrel of a template, in a direction which is not exactly parallel to the 'axis of the hole, but which can be tilted on its axis by an angle significantly greater than the tolerance set (more than 1 degree in the numerical example previously indicated); under these conditions, it suffices for the end of the tool, or of its guide member, to enter the hole entrance, so that it can then be completely engaged therein, thanks to

The exercise of a thrust, transmitted to the tool or to its • guide member by their support; this phase of engagement of the tool in the hole, for example in the barrel of a template, is in fact allowed by the fact that the tool, as well as its guide member, are supported in a tool holder , fixed itself at the end of the manipulator arm, by means of a joint comprising two Cardan joints, and that in addition the organs mentioned are balanced with respect to this Cardan joint; indeed, the thrust transmitted to the tool or to its guide member is certainly not directed exactly along the axis of the hole, but the walls of the latter provide the guidance of the end of the tool, or of its guide member, during their engagement in the hole, without the tool or its guide orga35 being subject to mechanical stresses capable of deforming or even breaking them.

It would obviously not be the same if the tool, or its guide member, was not balanced with respect to the universal joints, since then the engagement of the tool or its guide member in the hole, in a direction fairly inclined on its axis, would produce strong reactions from the wall of the hole, which would be liable to damage the tool or its guide member.

The engagement movement of the tool or its guide member in the hole can obviously be produced by the manipulator arm itself. However, in a preferred embodiment of the invention, the tool holder comprises an elongated frame, the first end of which is fixed to the end of the manipulator arm, and in which a carriage, supporting the tool, as well as its clamping and optionally actuating members, is mounted so as to be able to slide longitudinally between a rest position, corresponding to the approach of the hole, and a position of engagement of the tool in the hole, under the action of at least one motor, such as a jack, secured to the fixed frame.

This arrangement according to the present invention is advantageous insofar as it avoids causing the engagement movement to be controlled in the hole by the manipulator arm itself, which is very heavy, and whose movements therefore require a powerful motor and are relatively imprecise, as indicated above, this engagement movement being on the other hand controlled by a motor secured to the frame of the tool holder, which only has to move the tool, as well as its clamping members, and possibly actuation and guide; this specialized motor can therefore have reduced power, and it can control the engagement movement with higher precision.

As indicated above, it is the tool itself, for example the drill of the drill, which can be approached the entrance to the hole "then engaged in the latter while being guided by its internal wall; it is understood, however, that such direct guiding of the entry of the tool into the hole is possible, without risk of damage to the tool, only if the latter is particularly resistant, as is the internal wall of the hole, for example of the barrel, and if, in addition, the assembly fitted to the gimbal is perfectly balanced, which is generally only possible in the case of an assembly of relatively low weight.

When these latter conditions are not satisfied, as is the case for most industrial machining operations, use is preferably made of an embodiment of the invention, in which a tubular tool guide member is fixed to the clamping and optionally actuating members of the tool, by a connecting piece, means being further provided for sliding the tool in its guide member, between an erasing position and a working position, where the end of the tool leaves the guide member; in the case of this embodiment, the barrel must obviously have an internal diameter significantly greater than the nominal diameter of the tool, for example of the drill, by an amount corresponding substantially to the thickness of the tubular guide member of the tool.

This last embodiment of the invention is particularly advantageous insofar as the reactions developed by the internal wall of the hole, in particular of the template barrel, are collected exclusively by the guide member, since the tool is then in erasing position inside its guide member; it is of course always possible to give the wall of the tubular guide member a thickness sufficient to prevent said guide member from being deformed or damaged during the movement of penetration into the hole.

According to another advantageous characteristic of the invention, the connecting piece of the tool guiding member can have an internal conical bearing, coaxial with the tool and arranged so as to come to be applied, when the carriage supporting the tool, its guide member and its connecting piece, is brought back to the rest position, on an external conical bearing, provided at the second end of the fixed frame, concentrically to its longitudinal axis.

Thanks to this arrangement according to the present invention, the axis of the assembly formed by the tool, its guide member, and the connection piece of the latter to the clamping and possibly actuation members of the tool, which had ceased to be in the extension of the longitudinal axis of the sliding carriage during the movement of engagement of the guide member in the hole, in particular in the barrel of the template, is automatically brought back in the extension of this latter axis, thanks to the application of the internal conical bearing, fitted on the connecting piece, on the external conical bearing, fitted on the fixed frame. In this way, the whole of the tool and the tool holder is in a rest position, where their longitudinal axes are perfectly aligned, so that the angular position of the tool guide member is perfectly defined for the next machining operation. Of course, after the approach of the second hole, in particular of the second drilling barrel, the advance movement which the specialized motor communicates to the guide member and to its connection part, to make the first penetrate inside of the barrel hole, has the effect of separating the two conical bearings, applied hitherto one on the other, and thus allowing, again, the axis of the guide member to pivot relative to the 'longitudinal axis of the carriage.

In a particular embodiment of the invention, the clamping members, and possibly the tool drive, are fixed, preferably removably, on a sole, which is coupled to the sliding carriage by means of the two gaskets; this sole is preferably articulated by the first universal joint on a balancing counterweight support, which is itself articulated, by the second universal joint, on the sliding carriage.

This arrangement is particularly advantageous insofar as it makes the counterweights independent of the tool. Consequently, when the assembly of the tool, of its clamping and driving members, constitutes a hand tool, for example a drill with incorporated motor, fixed in a removable manner on the sole of the tool holder, this hand tool can be exchanged and replaced by another, possibly of different function and weight, and it then suffices to modify the counterweights, which are fixed # on the support preferably in a removable manner, to take account of the different weight of the new tool used.

By way of example, an embodiment of a device has been described below and illustrated diagrammatically in the appended drawing, to facilitate the introduction of the drill bit of a drill into a barrel of a drilling template.

Figures 1 and 2 schematically represent this embodiment in partial ccnpe by an axial plane, respectively in the approach phase of the barrel hole and in the phase of engagement of the tool guide member in the barrel .

Figures 3 and 4 are partial, but detailed views of this embodiment, in section along two axial planes, perpendicular to each other.

Figures 5 to 9 illustrate, on a larger scale, the successive phases of the introduction of the drill guide member into a barrel of the drilling template.

In FIGS. 1 and 2, P denotes a metal sheet, one face of which is placed on a support S, while, on its other face, a drilling template G is applied, generally comprising several guns such that c (it is acts of a ring of which an internal bore, or hole t, is calibrated, its axis, exactly perpendicular to the sheet P, being designated by a).

We have designated by β the longitudinal axis of an elongated frame 1 , the first end of which, located opposite the template G, is fixed to the end of the manipulator arm - not shown - of a robot; this manipulator arm can be of any suitable type, which it is not necessary to describe in detail, since there are many different embodiments of them, currently available commercially. The means for fixing the end 1a of the frame 1 to the end of the manipulator arm have also not been shown, since they are susceptible of many different embodiments, which do not come within the scope of the present invention. . Between the two ends, la and lb "of the frame 1, guide bars, 2a and 2b, extend parallel to the longitudinal axis β; they are used for guiding in translation, in the direction of the β axis, of a carriage, 3 , which has not been shown in detail in FIGS. 1 and 2, and which can be driven by a reciprocating movement. and back on the guide bars 2a and 2b, by at least one motor such as a jack, not shown.

In the illustrated embodiment, a drill wit h an incorporated motor, 4, is supported by the carriage 3, by means of several Cardan joints, 6, 6a, 6b. The drill 4 is preferably provided with a head, 4a, in which the clamping members are mounted, for example a mandrel 4b "of the drill 4c, which can slide between an erasing position, visible in FIG. 1, and a working position, visible in Figure 2. Drills of this type are already known, which it is not necessary to describe in detail, since the present invention is not limited to the use of a drill of this type. In its working position (Figure 2), the drill 4c engages in a tubular endpiece 5a, which constitutes a guide member for the drill 4c, as will be explained later in more detail, and which is joined to the body of the drill 4 by a connecting piece 5b.

As will be described later in more detail with the aid of Figures 3 and 4, the body of the drill 4 is articulated, by the first joint to the gimbal, 6, on a support 7r on which are fixed counterweights d 'balancing, 8, and which is itself articulated on the sliding carriage 3 by the second joints to the gimbal, 6a, 6b. Finally, as can be seen in FIG. 2, the connecting piece 5b has an internal conical bearing 9a, coaxial with the axis, γ, of the tool 4, and in particular of its drill 4c, while an external conical bearing, 9b, is arranged on the front part of the end 1b of the frame 1, concentrically with its longitudinal axis 8; as seen in FIG. 1, when the carriage 3 occupies its position closest to the end 1a of the fixed frame, the internal conical bearing 9a is applied to the external conical part 9b, so that the axis γ of the drill 4c is aligned with the axis 8 of the fixed frame 1.

The device which has been previously described with the aid of FIGS. 1 and 2, is used as follows:

Before a drilling operation, the various members 1 to 9 of the device according to the present invention are in their relative positions illustrated in FIG. 1; in other words, the carriage 3 occupies its extreme position, shown in solid lines, which is closest to the end 1a of the frame 1, just as the drill 4 is also in its corresponding extreme position, where the drill 4c is erased behind the tubular guide endpiece 5a, or at least inside of iti As a result of the corresponding position of the connecting piece 5b, the internal conical bearing 9a is applied against the bearing external conical 9b, so that the axis γ of the drill 4c and of the drill 4 is in the exact extension of the longitudinal axis β of the frame 1. The robot is then controlled - by known means, that it is not necessary to describe in detail - so that its manipulator arm - not shown -, at the end of which is fixed the end 1a of the frame 1 of the tool holder, approaches the tubular guide tip 5a of the entry of the barrel £ of the template drilling G. Due to the limited precision of the movements of the manipulator arm, it is generally not possible, during this approach movement, to align the axis β-γ exactly with the axis a of the barrel £; we have designated in Figure 1 by e, the shortest distance between the axes a and β-γ, on the one hand, and by £, the angle, generally quite small, between the two axes mentioned, assuming that they are in the same plane (which is rarely done in practice, since the position of the β — γ axis in space has three degrees of freedom relative to the fixed direction of the axis a of the barrel £ ).

When the manipulator arm of the robot has brought the tubular guide member 5a to its position closest to the entry of the barrel £, which corresponds for example to that illustrated in FIG. 1, or to a position in which the end of the guide member 5a is already practically at the entrance to the barrel c, the robot controls, by known means, which it is not necessary to describe in detail, the sliding of the carriage 3 until it position, shown in broken lines in Figure 1, the closest to the end lb of the frame 1. During its translational movement towards the template G, the carriage 3 drives towards the latter the drill 4 and the tubular end piece 5a and the connecting piece 5b, so that the internal conical bearing surface, 9a, of said part 5b ceases to be applied to the external conical bearing surface ^ 9 b, of the frame 1, and that the end of said endpiece 5a engages in hole t of barrel G .. This engagement movement is facilitated, as will be explained later in more detail, if the barrel c. has a divergent entry, as illustrated in FIGS. 1 and 2. During its engagement movement in the hole t of the barrel .ç, the tubular endpiece 5a is guided by the internal wall of its hole t, without being subjected to important reactions, since the weight of the assembly 5a-5b-4c-4b-4a-4-g-7 is balanced by the counterweights 8 with respect to the Cardan joints, 6a and 6b. As also the external diameter of the tubular guide end piece 5a is adapted to the internal diameter of the hole t of the barrel e so as to allow the engagement of one in the other without play or friction, or at least with very little friction, the reactions of the wall of the hole t of the barrel c have the effect of rotating the assembly 5a-5b-4c-4b-4a-4 around the joint to the Cardan joint 6, and the support 7 counterweights 8 around the Cardan joints 6a and 6b, in such a way that the axis γ of the drill 4c and of its guide member 5a, ceases to coincide with the axis β of the frame 1 and on the other hand comes to align itself exactly with the axis a of the hole t of the barrel I, as illustrated in FIG. 2. At the end of this movement of engagement of the guide member 5^at in the barrel ç, the robot controls the advance of the head 4a of the drill 4 so that its drill 4c passes through said guide member 5a and its end comes out of the barrel c to come into contact with the corresponding face of the sheet P. the robot then controls the rotation of the drill 4c by the motor of the drill 4 "so that said drill pierces right through the sheet P during the terminal phase of the advance of the head 4a of the drill 4 . the robot then controls the withdrawal of the head 4a from the drill 4 and its drill 4c to the rest position illustrated in FIG. 1, which has the effect of releasing the drill 4c from the hole drilled in the sheet P, then it controls the stopping of the drill 4 "motor as well as the sliding of the carriage 5 towards the end 1a of the frame 1; therefore, the internal conical bearing 9a is again applied to the external conical bearing 9b, which has the effect of rotating the assembly 5a-5b-4c-4a-4 relative to the joints at the Cardan joint 6, 6a, and 6b, and therefore to bring the axis T in the exact extension of the axis β; in the rest position illustrated in Figure 1, the drilling device can be moved by the manipulator arm of the robot to the level of another drilling gun of the same size, in order to perform a second drilling operation of sheet P, comprising exactly the same phases as that previously described. Of course, when the tubular end piece 5a leaves the barrel c, which ceases to guide it, the pivoting movements mentioned, with respect to the Cardan joints, have very limited amplitudes, and they are also accompanied by oscillations of low amplitude, due to the balancing obtained thanks to the counterweights 8; these possible oscillations can moreover be damped by well known devices, which it is not necessary to describe.

In the detail views of Figures 3 and 4, the same reference numbers have been used as much as possible as in Figures 1 and 2, previously described. We will therefore limit ourselves to the description of the parts of FIGS. 3 and 4 which represent parts not detailed in FIGS. 1 and 2. In order not to interfere with the visibility of FIGS. 3 and 4, the various elements of the drill, 4, 4a, 4b and 4c, have been represented therein in phantom lines SJ as indicated, it is a drill with incorporated motor, the head 4a of which can be moved between a rest position, visible in FIG. 3, and a working position, visible in FIG. 4, for example by a jack, pneumatic or hydraulic, also incorporated in the drill 4; the power supplies, in electric current or in pressurized fluid, have not been shown for this jack and for the electric motor driving the drill 4, the corresponding supply cables or pipes being generally guided towards the drill by the arm manipulator - not represented - of the robot. This drill ', which can be of a commercially available type, is removably fixed, for example by means of screws designated by 10 in FIG. 3, on a soleplate 11, on the underside - in FIG. 3 - Which detaches a sub-sole, 11a, parallel to the sole 11; a pivot 12 at its ends engaged in recessed bearings, one opposite the other, in the sole 11 and in the sub-sole liaJ the middle part of the pivot 12 passes through the base 13a, in a first piece in U-shaped, 13, so that this part 13 can pivot around a first axis A, which coincides with that of the pivot 12, and which is therefore perpendicular to the sole 11. A second U-shaped part, 14, has its two branches, 14b and 14c, respectively articulated on the lateral branches,

13b and 13c of the first U-shaped part, 13; these two joints are materialized respectively by pivots 15b and 15c, whose geometric axes are aligned along a second pivot axis, B, which intersects the first axis A at a right angle. The part 14 is thus joined to the sole 11, on which the drill 4 is fixed, by means of a first joint to the gimbal, of axes A and B. The two branches,

14b and 14c, of the second U-shaped part, 14, are extended respectively, opposite its base, 14a, and towards the end 1a of the frame 1, by two first arms, 14d (and 14e not visible on the Figures 3 and 4), which respectively carry the first counterweights 8d (and 8e, not visible) ·. The base 14a of the second U-shaped part, 14 is itself extended in the direction of the end 1a of the frame 1, by a second, single, median arm, I4f, the end of which is located on the end side. 1a of the frame 1, and at a certain distance below the first arms 14d and 14e, carries a second counterweight 8a.

The second arm, 14f of the second U-shaped part, 14, is itself articulated on the base, 15a, in particular in the form of a fork, of a third U-shaped part, 15; this articulation is embodied by a pivot 16, the ends of which are engaged in two recessed bearings, one facing the other, in the two parts of the fork-shaped base 15a, so that the part 15 can pivot relative to the base 14a of the part 14 around a third axis, C, perpendicular to the base 14a. The branches, 15b (and 15c, not visible in FIGS. 3 and 4) of the third U-shaped part, 15, are themselves articulated respectively on parts integral with rings 3a and 3b, which are threaded respectively on the bars of guide, 2a and 2b, of the frame 1, with the interposition of rolling balls, not shown. As can be seen in FIG. 4, the respective articulations of the branches 15b and 15c of the U-shaped part, are materialized by pivots, 16b and 16c, aligned along the same fourth axis D, which intersects the third axis C at a right angle. In this way, the second piece at ü, 14, which carries the counterweights 8a, 8d and 8e, is supported by the rings 3a and 3b, constituting the sliding carriage 3, by means of a second universal joint, of axes C and D.

In FIGS. 5 to 9 only a drilling cannon c has been shown, as well as the tubular guide end piece 5a, and its connecting piece 5b, of the device described above, to explain in more detail the engagement movement of the 'guide member 5a in the hole t of the barrel and explain certain improvements capable of further facilitating this movement of engagement. As already indicated, the hole t of the drilling barrel c preferably has a flared entry v, while the end of the tubular end piece 5a preferably has a head, 5al, curved externally, in particular in the form of spherical cap, followed by a neck, 5a2, with regular profile, that is to say which regularly connects the head 5al to the rear, cylindrical part, 5â3 of the nozzle 5a. In FIG. 5, which illustrates a position of the tubular endpiece 5a in which its head 5al approaches the flared entry v of the hole t of the barrel c, it is clearly seen that the axis γ of the endpiece 5a n ' is not in the extension of the axis a of the hole t. In FIG. 6, the start of the engagement movement of the head 5al in the flared entry v has been illustrated in solid lines and, in mixed draft, of the successive subsequent positions of said head during its engagement movement Guided by the flared entrance c. This figure / clearly shows the advantages which result on the one hand from the domed shape of the head 5al and on the other hand from the flared entry v of the barrel c. The usefulness of the neck 5a2 can be deduced from FIGS. 6 and 7, in the case in particular where the axis γ of the tubular endpiece 5a would, with the axis a of the hole t, make an angle of a few degrees, significantly greater than that visible in FIG. 5; in this case, the circular edges, front and rear, or at least one of the two, of the flared entry v would cooperate with the regular sides of the co ^ to facilitate the movement of engagement and reduce the importance of shocks due the significant misalignment of the axes a and γ. In the position illustrated in FIG. 7, where the domed head 5al has reached the entrance to the cylindrical part of the hole t, the misalignment of the axes a and γ is already very greatly reduced and is almost eliminated as soon as, as illustrated in FIG. 8, the rear, cylindrical part, 5a3, of the end piece 5a begins to engage in the cylindrical part of the hole t. Figure 9 shows the working position of the guide member 5a, which then passes right through the barrel c, so that it can then guide the drill - not shown - in contact with the sheet to be drilled.

Finally, it can be seen in FIGS. 5 to 9 that the part of the tubular guide member 5a, which is embedded in the connection piece 5b "may include a channel, in particular radial, 5a4, which, at one end, opens into / * central hole used for the passage of the drill bit - not shown - while its other end can be supplied, by a channel passing through the connection piece 5b, either with a lubricating liquid, or with air to expel the metal shavings ; of course, two separate channels could be assigned respectively to these functions.

The present invention is not limited to the

- 16 2555083 previously described embodiment. It encompasses all of its variants, only a few of which will be indicated, by way of nonlimiting examples.

the device according to the present invention can be used to facilitate the introduction of any tool, or even possibly of a tracing point or of another recording member, into a barrel of a template, or more generally , in a hole of complementary shape, at the bottom of which the tool must come into action. Instead of being a drill, the tool could be a cutter, a screwing or tightening tool, such as a screwdriver, a wrench, etc. For certain applications, one could consider mounting on the sole 11, only the tool clamping members (functionally equivalent to the head 4a-4b of the drill 4), as well as the means for moving them between the rest position. and the working position, where the end of the tool leaves the tubular guide endpiece, the actuating member being itself carried either by the fixed frame or by the manipulator arm, and being connected by a flexible transmission to the tool itself, the conical bearing surfaces (9a and 9b in FIGS. 1 to 4) could be replaced by other members for guiding the connecting piece 5b relative to the end lb of frame 1. The external shape of the tubular guide member, and in particular of its head, is optional material; the corresponding tubular end piece could have a cylindrical outer surface, terminated towards the front by a converging frustoconical surface intended to cooperate with the entry of the barrel. As already indicated, it is possible to remove, in certain applications, the tool guiding member, in particular the corres5 laying tubular endpiece, and to have the end of the tool guided. through the side wall of the barrel hole.