EP0055648B1 - Machine for work-pieces having a curved surface of a given shape - Google Patents

Description

The invention relates to machines for producing parts with left surfaces of determined configuration, which comprise a group of shaping elements, in particular cylindrical rollers mounted idly in rotation individually next to each other, respectively, on carriers. rollers themselves mounted on a support movable relative to a workpiece table, so that said roller holders can move individually parallel to a common direction perpendicular to that of the axes of the rollers under the action of control means suitable such as, for example, a numerical control in which said determined left configuration is memorized, as well as means for rolling, against a part of the periphery of all of said shaping rollers, an endless strip which takes, at a configuration corresponding to the instantaneous envelope curve of the straight sections of the rollers and constitutes a tool for drilling mage of parts with variable profile.

We already know, for example from US Patent No. 3,022,611, a machine of this kind in which the forming elements, consisting of small orientable blocks arranged side by side, are each carried by one end of a finger corresponding block slidingly mounted in a support, the other ends of said fingers pressing, under the action of springs, against one of the ends of a corresponding group of slides which in turn support themselves, under the action of springs, by their other end, against cams carried by a rotary shaft for controlling the profile to be executed on the part. However, such a structure is relatively bulky and complicated.

The object of the invention is to produce a machine of the kind in question which does not have the aforementioned drawbacks of the machine known from the American patent indicated above.

To this end, according to the invention, each roller carrier is in the form of an elongated frame which carries, at its end in the form of a yoke, the shaping roller, and which is crossed by the aforementioned common support to all the roller carriers mounted to slide in said support, the means for controlling the movements of the roller carriers being interposed between said support and each of the roller carriers.

Thanks to this particular structure, given that each roller carrier is in the form of a frame through which the common support passes, the means for controlling the movements of the roller carriers, interposed between said common support and each of the roller carriers , naturally find their place inside said frames, which makes it possible to produce a simple and compact overall structure, which was not the case in the aforementioned known machine.

In addition, the structure according to the invention makes possible a solution which was not in the known machine, namely: being able to provide each roller holder, at its other end, with an auxiliary roller, the center distance of the two rollers being immutable and identical on all the roller carriers, and being able to pass, over all the rollers, a single inextensible stretched belt elastically deformable in transverse direction only, while an abrasive strip rests against the rollers of conformation by means of said belt. This advantageous solution will be described in detail below.

Without going into the description of structural details, it is immediately understandable that such a machine makes it possible, for example if the endless belt is an abrasive belt, to machine left surfaces in materials with characteristics, in particular of very variable hardnesses , by removing material in possibly large quantities, and with a surface finish as fine as desired, for example comparable to that obtained by grinding processes, since it is a machining by abrasion.

The machine takes a very particular interest if the various mobile parts which it comprises are equipped with servo-controls slaved to a programming system in which one can memorize all the characteristics of a complete cycle of machining of a surface left defined mathematically by Cartesian and / or polar coordinates; it suffices to use, for this purpose, the known principles of so-called numerically controlled machine tools.

The invention will be better understood on reading the description which follows and on examining the appended drawings which show, by way of nonlimiting examples, two embodiments of a machine according to the invention applied to machining by abrasion.

• - la fig. 1 est une vue en plan du premier mode de réalisation;
• - la fig. 2 montre, à plus grande échelle, la partie de la machine de la fig. 1 comportant l'unité d'usinage qui est à la base de l'invention;
• - la fig. 3 montre, à plus grande échelle encore et avec des parties en coupe, les organes principaux de l'unité d'usinage avec d'avantage de détails que que sur la fig. 2;
• - la fig. 4 est une vue en plan, avec des arrachements correspondant à la fig. 3;
• - la fig. 5 est, à plus grande échelle, une coupe transversale faite suivant la ligne V-V de la fig. 3;
• - la fig. 6 est, également à plus grande échelle, une coupe transversale partielle faite suivant la ligne VI-VI de la fig. 3;
• - la fig. 7 est une vue analogue à celle de la fig. 3 et illustre une variante; et
• - la fig. 8 est une vue en plan correspondant à la fig. 7.

In these drawings:

• - fig. 1 is a plan view of the first embodiment;
• - fig. 2 shows, on a larger scale, the part of the machine of FIG. 1 comprising the machining unit which is the basis of the invention;
• - fig. 3 shows, on a still larger scale and with parts in section, the main members of the machining unit with more details than in FIG. 2;
• - fig. 4 is a plan view, with cutaway parts corresponding to FIG. 3;
• - fig. 5 is, on a larger scale, a cross section made along the line VV of FIG. 3;
• - fig. 6 is, also on a larger scale, a partial cross section made along the line VI-VI of FIG. 3;
• - fig. 7 is a view similar to that of FIG. 3 and illustrates a variant; and
• - fig. 8 is a plan view corresponding to FIG. 7.

The abrasion machine represents in a simplified manner, in fig. 1, essentially comprises a frame designated in its example by 1 with a bench 2 for supporting a carriage 3 workpiece carrier 4 to be machined and a bench 7 for supporting a carriage 8 carrying the machining unit 9. These two benches extend respectively in two horizontal directions perpendicular to each other.

The workpiece carrier 3 slides on the bench 2 under the action of an electric motor 12 via a transmission which includes a ball screw 13 rotatably mounted in the frame of the bench 2 and a nut 14 secured to the carriage 3. The workpiece 4 is, in the example, an elongated part, such as a propeller blade; it is supported, by one of its ends, by a tailstock 16 fixed on the carriage 3, and by its other end, in the mandrel 17 of a rotary divider plate 18 driven by an electric motor 19.

The machining unit carriage 8 slides on the bench 7 under the action of an electric motor 23 via a transmission which comprises a ball screw 24 rotatably mounted in the frame of the bench 7 and d 'A nut 25 secured to the carriage 8.

The machining unit 9 (see also fig. 2) has an endless abrasive belt 31 which passes over support and guide members carried by the carriage 8 and comprising a guide assembly 32, a drive roller 33 driven by a motor (not shown), an idler idler roller 34, and a tensioner roller 35 subjected to the action of a spring 36. All these members are covered with a protective plate which masks them in FIG. 1, but which is assumed to be removed in FIG. 2.

It is the guide assembly 32 which constitutes the dominant part of the machine. It comprises an endless belt 38 (see also fig. 3 and 4) against which the abrasive belt 31 is in direct contact and which is itself supported and guided by two groups of cylindrical rollers, namely: a group of rollers conformation 41 and a group of auxiliary rollers 42. In the example, there are five rollers in each of the two groups, but this number could be different depending on the applications envisaged. Thus, the abrasive belt is not in direct contact with said rollers, but it bears against them by means of the tensioned endless belt 38. The rollers are associated in pairs each having a shaping roller 41 and an auxiliary roller 42 individually mounted for rotation in the two ends, respectively, of a roller carrier 45 of generally elongated shape and flat section. Each roller 41 or 42 is carried by a bearing 47 mounted on an axis 48 fixed between the two branches of a yoke formed on the corresponding end of the roller holder. In the example, there are five roller carriers 45 arranged next to each other, as shown, and movable individually, with respect to each other, in longitudinal direction, so that the shaping rollers are located side by side and can be moved relative to each other, in both directions in a direction which is parallel to the longitudinal direction of the roller carriers. On each roller holder, the distance between the axis of the shaping roller and the axis of the auxiliary roller is immutable, by construction, and this distance is the same on all the roller holders.

The central part of each roller carrier 45 has a very large recess 51. In other words, each roller carrier is in the form of a very elongated frame terminated by two thin yokes between the branches of which are the shaping roller and the auxiliary roller. The large sides of the frame have an irregular, but symmetrical, pentagon-shaped section, as can be seen in Figs. 4 and 6, with two right dihedral angles adjacent to their outer face, two obtuse dihedral angles and a fifth dihedral angle, the two faces of which are in contact with rollers 53 housed in a slide 54 of section in the shape of a "V" combined with that of the frame. All the slides 54 are cut in a common support 55 which extends through the openings 51 of all the roller carriers and which is provided with a flange 56 by means of which this support can be fixed on the carriage 8 (fig 2) by screws 57.

The belt 38 is inextensible in the longitudinal direction, but it is elastically deformable in the transverse direction, so that, when a roller carrier 45 is moved longitudinally relative to the neighboring roller carriers, the part of the belt 38 which is in contact with the shaping rollers 41 follows the envelope surface of the corresponding parts of the preferably rounded outer surface of said rollers, as can be seen on the right-hand part of FIG. 4. The abrasive strip 31 which covers the belt 38 therefore has the same configuration. It will now be understood that if, by suitably programmed relative displacements of the roller carriers 45, the adhesive strip is given any suitable left configuration, in synchronism with corresponding programmed displacements of the workpiece, a tool is available. variable profile specific to the execution of any mathematically defined left surface.

To ensure the programmed movements of the roller carriers, different means can be used. Fig. 3 illustrates a solution by hydraulic means. In the axis of the opening 51 of each roller holder 45, is fixed a cylindrical rod 61 which constitutes the piston rod 62 of a hydraulic cylinder 63 whose cylinder 64 is cut in the common support 55. Depending on whether oil is sent under pressure to chamber 67 or to chamber 68 of the jack, the roller holder is advanced and, with it, the shaping roller 41 towards the workpiece or, on the contrary, it away from it. The hydraulic circuits have not been shown in detail, since this is a well known technique. It has been indicated, in figs. 3 and 6, a linear sensor 72 whose rule 73 is secured to the common support 55 and the slider 74 secured to the piston rod 61 of the jack, to ensure the closing of the "control loop".

The machine is equipped with a digital control installation in which the characteristics of the left surface to be machined are recorded and which automatically controls the motor 12 for moving the workpiece carrier 3, the motor 19 for rotating the workpiece. machine 4, the motor 23 for moving the carriage 8 machining unit holder 9, as well as controlling the servo-valves supplying the hydraulic cylinders for controlling the movement of the roller carriers 45.

Figs. 7 and 8 illustrate a solution by mechanical means to ensure the movement of the roller carriers 45, in the form of a control by ball screw 81 secured to each of the roller carriers 45 and engaged in a conjugate threaded bush 82 mounted madly in rotation, without axial displacement, in the common fixed support 55A for this purpose suitably hollowed out also. The threaded sleeve 82 has an extension 84 in the form of a grooved pulley over which passes a toothed belt 85 which also passes over another grooved pulley 86 fixed on the shaft 87 of a small electric motor 88 carried by the common fixed support 55. The toothed belt transmissions 85 associated with the different roller carriers are offset from one another (see fig. 8).

The operation of the machine equipped with this device is similar to that of the machine equipped with the hydraulic device described above. The digital control installation controls the electric motors 88 to rotate them, either in one direction or the other and thus move the different roller carriers 45 forward or backward, in the same way as by the hydraulic cylinders.

Claims (5)

1. A machine for making workpieces having a curved surface of a given shape, comprising a group of cylindrical forming rollers (41) mounted for loose rotation individually beside one another on roller holders (45) in turn mounted on a support (55) which is movable with respect to a workpiece-holder table (3), so that the said roller holders can move individually parallel to a common direction perpendicular to that of the axes of the rollers in response to suitable control means (63, 81, 82) such as, for exemple, a numeric control in which the said given curved shape is memorized, and means (33) whereby an endless belt (31) can be rolled against part of the periphery of the group of said rollers, the endless belt having at this place a configuration corresponding to the instantaneous enveloping curve of the cross-sections of the rollers and constituting a tool for forming workpieces of varying profile, the said machine being characterised in that each roller holder (45) is in the form of a frame of elongate shape having the forming roller (41) at its forked end and the said support (55) common to all the roller holders mounted slidably in said support extends through said frame, the roller holder movement control means (63, 81, 82) being interposed between said support and each of the roller holders.

2. A machine according to claim 1, applied to the machining of workpieces by abrasion, characterised in that the endless belt is an abrasive belt (31).

3. A machine according to claim 2, characterised in that each roller holder (45) has at its other end an auxiliary roller (42), the spacing between the axes of the two rollers being fixed and identical for all the roller holders, and in that a single non-extensible stretched belt (38) which is elastically deformable in the transverse direction only passes over all the rollers while the abrasive belt (31) bears against the forming rollers (41) through the agency of said belt (38).

4. A machine according to any one of claims 1 to 3, characterised in that the means for controlling the movements of each roller holder in the support are in the form of a screw and nut connection (81, 82), the rotary element (82) of which is connected to an individual rotary control shaft (87) by said support outside the roller through the agency of a chain or toothed belt transmission (85), the transmission associated with the different roller holders being offset from one another in the direction of movement of the roller holders.

5. A machine according to any one of claims 1 to 3, characterised in that the means for controlling the movements of each roller holder (45) in the support are in the form of a hydraulic jack (63), the two elements of which are respectively connected to the support (55) and the corresponding roller holder (45).

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