EP0055648A2 - Machine for work-pieces having a curved surface of a given shape - Google Patents

Abstract

Machine tools. The machine comprises a group of cylindrical shaping rollers (41) mounted idly next to each other on roller carriers (45) movable on a support (55) parallel to a direction perpendicular to that of the axes of the rollers under control. of a numerical control, as well as means (33), for causing an abrasive strip (31) to roll against a portion of the periphery of the set of rollers, which takes, at this location, a configuration corresponding to the envelope curve instant of the straight sections of the rollers and constitutes a tool for machining by abrasion of variable profile. The machine can be used for machining surfaces with a left configuration, in the most varied materials.

Description

The subject of the invention is a machine for producing parts having left surfaces of determined configuration, for example for the machining by abrading of air or marine propeller blades, of sheet metal stamping tools in aeronautical or automotive construction. , models of vehicles or aircraft, etc ...

The machine according to the invention comprises a group of cylindrical conformation rollers mounted idle for rotation individually, one next to the other, respectively, on roller holders themselves mounted on a support movable relative to a workpiece table , in such a way that said roller carriers can move individually parallel to a common direction perpendicular to that of the axes of the rollers under the action of suitable control means such as, for example, a numerical control in which said definite 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 this location, a configuration corresponding to the instantaneous envelope curve of the straight sections of the rollers and is a tool for forming parts with variable profile.

In a machine 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, a roller, and which is crossed by the aforementioned support common to all roller carriers slidingly mounted in said support, the means for controlling the movements of the roller carriers being interposed between said support and each of the roller carriers.

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 state as fine as desired, for example comparable to that obtained by grinding processes, since it is a machining by abrasion.

The machine takes on a very special interest if the various mobile parts it comprises are equipped with servo-controls slaved to a programming system in which one can memorize all the characteristics of a complete cycle for machining a left surface mathematically defined 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 figure 1 est une vue en plan du premier mode de réalisation
• - la figure 2 montre, à plus grande échelle, la partie de la machine de la figure 1 comportant l'unité d'usinage qui est à la base de l'invention ;
• - la figure 3 montre, à plus grande échelle encore et avec des parties en coupe, les organes principaux de l'unité d'usinage avec davantage de détails que que sur la figure 2 ;
• - la figure 4 est une vue en plan, avec des arrachements correspondant à la figure 3 ;
• - la figure 5 est, à plus grande échelle, une coupe transversale faite suivant la ligne V-V de la figure 3 ;
• - la figure 6 est, également à plus grande échelle, une coupe transversale partielle faite suivant la ligne VI-VI de la figure 3 ;
• - la figure 7 est une vue analogue à celle de la figure 3 et illustre une variante ; et
• - la figure 8 est une vue en plan correspondant à la figure 7.

In these drawings:

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

The abrasion machining machine shown in a simplified manner, in FIG. 1, essentially comprises a frame designated as a whole by 1 with a bench 2 for supporting a carriage 3 workpiece carrier 4 and a bench 7 for supporting a carriage 8 for the machining unit holder 9. These two benches extend respectively in two horizontal directions perpendicular to one another.

The workpiece carrier 3 slides on the bench 2 under the action of an electric motor 12 via a transmission which includes a bill screw 13 rotatably mounted in the frame of the bench 2 and a nut 14 integral with 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 a nut 25 secured to the carriage 8.

The machining unit 9 (see also FIG. 2) comprises 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 moved 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 Figure 2.

It is the guide assembly 32 which constitutes the dominant part of the machine. It comprises an endless belt 38 (see also Figures 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 shaping rollers 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 strip 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 slide 42 individually mounted for rotation in the two ends, respectively, of a roller carrier 45 of generally elongated shape and of 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 one beside the other, as shown, and movable individually, with respect to each other, in the longitudinal direction, so that the shaping rollers are located next to each other from each other and can be moved relative to each other, in both directions of 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 long 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 external face, two obtuse dihedral angles and a fifth dihedral angle, of which the two faces 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 from 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. Figure 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 4, of 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.

Figures 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 integral with each of the roller carriers 45 and engaged in a threaded socket conjugate 82 madly mounted for rotation, without axial displacement, in the common fixed support 55A for this purpose also suitably hollowed out. 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 Figure 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)

l.-machine for producing parts having left surfaces of determined configuration, which comprises a group of cylindrical shaping rollers (41) mounted idly individually rotating next to each other respectively, on roller holders (45) mounted themselves on a support (55) movable relative to a work-holding table (3), so that said roller carriers can move individually parallel to a common direction perpendicular to that of the axes of the rollers under the action appropriate control means (63, 81, 82) such as, for example a numerical control in which said determined left configuration is stored, as well as means (33) for rolling, against a part of the periphery of the assembly of said shaping rollers, an endless strip (31) which, at this point, takes a configuration corresponding to the instantaneous envelope curve of the straight sections of the rollers and constitutes a tool for forming variable profile parts, said machine being characterized in that each roller carrier (45) is in the form of an elongated frame which carries at its end, in the form of a yoke, a roller, and which is crossed by the aforementioned support (55) common to all the roller carriers slidably mounted in said support, the means (63, 81, 82) for controlling the movements of the roller carriers being interposed between said support and each of the roller carriers . 2. Machine according to claim 1, applied to the machining of parts by abrasion, characterized in that the endless belt is an abrasive belt (31). 3.- Machine according to claim 2, characterized in that each roller carrier (45) is provided at its other end with an auxiliary roller (42), the distance between the two rollers being immutable and identical on all roller carrier, and in that a single inextensible stretched belt (38) elastically deformable in transverse direction only, passes over all the rollers, while the abrasive strip (31) bears against the shaping rollers (41) by through said belt. 4.- China according to one of claims 1 to 3, characterized in that the means for controlling the movements of each roller carrier in the support are constituted by a connection by screw and nut (81, 82) including rotary element (82) is connected to an individual rotary control shaft (87) carried by the aforementioned support, outside the roller carriers, by means of a chain or toothed belt transmission (85), the transmissions associated with the different roller carriers being offset from each other in the direction of movement of the roller carriers. 5.- Machine according to one of claims 1 to 3, charac-. terized in that the displacement control means 1 of each roller carrier (45) in the support are constituted by a hydraulic cylinder (63), the two elements of which are integral, respectively, with the support (55) and with the roller carrier ( 45) corresponding.

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