The present invention relates to a Cartesian machine tool, of the type with a horizontal slide and a machining head supported in a cantilever manner by said slide.

Nowadays machine tools are known of the type with a horizontal slide and a machining head supported in a cantilever manner by said slide, which typically comprise:

- a slide carriage, with respect to which the slide can move horizontally according to a first direction with corresponding means of horizontal translation,

- and a carriage tower for moving, according to a second direction, the slide carriage vertically with means of vertical translation.

The tower, further, slides on a footing in a third direction, perpendicular to the other two.

Typically the accuracy of such large-sized Cartesian machine tools

(with excursion of the axes greater than 3 meters) is limited by structural deformations that affect the elements of the supporting frame and of the slide proper, and these deformations vary as a function of the excursion of the slide.

In order to correct the positioning errors owing to structural deformations of the elements of the slide, nowadays systems are known and used which act by making the sliding guides of the slide deform.

However, such systems have the severe drawback that they allow the introduction of geometric errors that can then be difficult to control during detection and correction.

The aim of the present invention is to provide a Cartesian machine tool that is capable of restoring the correct configuration of a machining head, without deforming the sliding guides of the slide, and in general without introducing deformations into the means of guiding the movable elements of the machine.

Within this aim, an object of the invention is to provide a Cartesian machine tool in which the position of the machining head can be rapidly corrected with respect to any deviations with respect to a preset position.

Another object of the invention is to provide a Cartesian machine tool with operational performance levels that are not lower than conventional Cartesian machine tools.

Another object of the invention is to provide a slide carriage for a Cartesian machine tool as per the main aim.

This aim and these and other objects which will become better evident hereinafter are achieved by a Cartesian machine tool, of the type with a horizontal slide and a machining head supported in a cantilever manner by said slide, according to claim 1, and also by a slide carriage according to claim 9.

Further characteristics and advantages of the invention will become better apparent from the detailed description that follows of a preferred, but not exclusive, embodiment of the Cartesian machine tool and of the slide carriage according to the invention, which are illustrated, by way of non- limiting example, in the accompanying drawings, wherein:

- Figure 1 is a perspective view of a Cartesian machine tool according to the invention;

- Figure 2 is a perspective view of a slide carriage of a Cartesian machine tool according to the invention;

- Figure 3 is a portion of a cross-sectional side view of the slide carriage of Figure 2;

- Figure 4 is another portion of a cross-sectional side view of the slide carriage of Figure 2.

With reference to the figures, a Cartesian machine tool according to the invention is generally designated with the reference numeral 10. Such Cartesian machine tool is of the type with a horizontal slide 11 and a machining head 12 supported in a cantilever manner by the slide 11.

The Cartesian machine tool 10 comprises:

- a slide carriage 13, with respect to which the slide 11 can move horizontally with corresponding means of horizontal translation 14, better described hereinbelow

- a post 15, which comprises two opposite guiding columns 16 and 17 for the vertical movement of the slide carriage 13 with means of vertical translation 18, also better described hereinbelow.

The peculiarity of the invention consists in that the slide carriage 13 comprises:

- an external jacket 19 coupled to the post 15 with the means of vertical translation 18,

- an internal frame 20 within which the slide 11 is arranged so as to slide with the means of horizontal translation 14,

- pivoting means 21 between the external jacket 19 and the internal frame 20, which are adapted to allow the inclination of the slide 11 with respect to an optimum horizontal configuration of use,

- means 22 of compensating the inclination, which are adapted to restore the optimum horizontal configuration of use of the slide 11.

The two guiding columns 16 and 17 are preferably symmetrical.

The means of vertical translation 18 are constituted, for example, by two recirculating-ball screws 27, arranged symmetrically with respect to a longitudinal central plane of the slide 11.

There are further two hydraulic linear actuators 23 and 24, one for each one of the guiding columns 16 and 17, each one fixed to the respective column and arranged so as to act on the slide carriage 13, in order to compensate the weight of the assembly of carriage 13 and slide 11.

There are also two symmetrical pairs of vertical tracks 25 and 26. The external jacket 19 of the slide carriage, coupled to the post 15 with the means of vertical translation 18, is constituted by a box-like body inside which there is a through compartment in which the internal frame 20 is accommodated.

The external jacket 19 supports the compensating means 22, which are described below.

The internal frame 20, within which the slide 11 is arranged so as to slide with the means of horizontal translation 14, is constituted by a lightened tubular body, which is fixed in a cantilever manner to the external jacket 19 by the pivoting means 21, therefore only on the side from which the end of the slide 11 that supports the machining head 12 protrudes.

The pivoting means 21 between the external jacket 19 and the internal frame 20 comprise, in the present embodiment of the invention, which is obviously not limiting:

- a lower rotation plate 30, which is elastically deformable and is fixed in a lower region to a lower edge 31 of the external jacket 19 and in an upper region to the lower wall 32 of the internal frame 20, for example with screws 33 as in Figure 3; the lower plate 30 is designed to flex outward, defining an axis of instantaneous rotation X which is horizontal and perpendicular to the plane of motion of the slide 11, for the internal frame 20 and therefore for the slide 11 supported by the internal frame 20;

- an upper containment plate 34, which is fixed to an upper edge 35 of the external jacket 19, for example with screws, and rests against an upper edge 36 of the internal frame 20; the upper plate 34 cooperates with the elastic return of the lower plate 30 to its starting shape structure, and therefore with the return of the internal frame 20 to its horizontal operational position.

The lower plate 30 and the upper plate 34 are both metallic, of a thickness such that they are able to perform the specific functionalities described above.

The means 22 of compensating the inclination, for example a downward inclination, adapted to restore the optimum horizontal configuration of use of the slide 11, are constituted by two vertical-axis linear thrust actuators 38 and 39, fixed to a rear part 40 of the external jacket 19 and arranged so as to push from top to bottom on the rear end 41 of the internal frame 20, as in Figure 4.

As mentioned, the internal frame 20 is coupled in a cantilever manner to the external jacket 19 by way of the lower plate 30, and the rear end 41 of the internal frame 20 is cantilevered and rests only on rear supporting raised portions 42.

The vertical-axis linear thrust actuators 38 and 39 each comprise an electric motor 45, which is fixed to the rear part 40 of the external jacket 19 and is adapted to rotate a driven secondary shaft 46 which in turn supports a pusher body 47 by way of a threaded coupling, the rotation of the secondary shaft 46 causing the raising or lowering of the pusher body 47 according to the direction of rotation of the driven secondary shaft 46.

Corresponding centering recesses 48 are defined at the regions of the internal frame 20 on which the pusher bodies 47 push.

The linear thrust actuators 38 and 39, commanded automatically, act proportionally with respect to the cantilevered position of the machining head 12, i.e. the further the slide 11 is extracted from the slide carriage 13, the greater is the vertical lowering imposed by the linear actuators 38 and 39 on the rear end 41 of the internal frame 20.

The means of horizontal translation 14 of the slide 11 with respect to the slide carriage 13 are constituted by a linear actuator of the type with a lead screw and an endless screw 50, in which the lead screw 51 is fixed to the slide 11, as in Figure 4, and can translate freely within a longitudinal slotted opening 55 defined on the internal frame 20, while the endless screw 52 is supported in a front region with a front bearing support 53 which is fixed to the internal frame 20 and in a rear region with a rear bearing support 54 which is also supported by the internal frame 20; in this manner the endless screw 52 is not affected by deformations of the endless screw 52 - lead screw 51 system, thus avoiding both irregularity of motion and the occurrence of abnormal stresses that might compromise the reliability of the machine 10.

The screw 52 is rotated about its own main axis by a gearmotor 60 by way of a belt-and-pulley system 61.

The gearmotor 60 is supported by a corresponding tail bracket 63 which is integral with the external jacket 19.

It should be understood that the invention also relates to a slide carriage 13 as described above, for machine tools of the type with a horizontal slide 11 and a machining head 12 supported in a cantilever manner by the slide 11, the latter being able to move horizontally with corresponding means of horizontal translation 14.

The slide carriage 13 is characterized in that it comprises:

- an external jacket 19 coupled to a post 15 with means of vertical translation 18,

- an internal frame 20 within which the slide 11 is arranged so as to slide with means of horizontal translation 14,

- pivoting means 21 between the external jacket 19 and the internal frame 20, which are adapted to allow the inclination of the slide 11 with respect to an optimum horizontal configuration of use,

- means 22 of compensating the inclination, which are adapted to restore the optimum horizontal configuration of use of the slide 11.

The Cartesian machine tool 10 according to the invention therefore entails a system for moving a slide carriage 13 that carries with it the entire translation mechanism of the slide 11 ; the rotation about a constraint of the internal frame 20 with respect to the external jacket 19 of the slide carriage 13 makes it possible to obtain in real time the compensation of the deformation of the extracted slide 11, such deformation being due to the force of gravity as a function of the position of the machining head 12 in space.

Such system, integrated with numerical control, achieves the aim of correcting the positioning errors owing to structural deformations of the elements of the slide 11 and overcomes the drawbacks of conventional systems that act by making the sliding guides of the slide deform, such systems in this way introducing geometric errors that are difficult to control.

Such system for compensating the drop of the slide 11 entails, specifically, the use of a post 15 that comprises two symmetrical opposite guiding columns 16 and 17 for the vertical movement of the slide carriage, which is composed of an external jacket 19, functioning as main carriage, and of an internal frame 20, functioning as counter-carriage, which, in order to compensate the drop of the slide, rotates, inside the external jacket 19, about a fixed axis which is provided with a metallic lower plate that is rigid for the translation of the slide but flexible for the rotation; the means of vertical translation 18 are also symmetrical as described above.

In this manner the sliding guides of the slide are not affected by the deformation, which is concentrated on elements that are especially designed for that purpose, i.e. the lower plate 30 and the upper plate 34, so that the external jacket 19 bears the stresses and the internal frame 20 rotates, but deformations are not induced either in the external jacket or in the internal frame, only movements (rotations).

The symmetry of the means of translation 18 and of the columns 16 and 17 of the post 15 cooperate significantly in optimizing the functionality of the invention.

The invention also has, in addition to the pivoting means constituted by the lower and upper plates, the means of compensating the inclination, which are constituted by a pair of numerically-controlled gear motors, which push, with a linear movement, on the rear part of the internal frame 20 and make it rotate in the opposite direction with respect to the rotation forward and downward of the slide 11 and therefore of the internal frame 20 proper.

The Cartesian machine tool 10 according to the invention, furthermore, by way of the external jacket 19 of the slide carriage 13, encloses the internal frame 20 that supports the slide 11 on both sides, supporting it at the front with the lower plate 30 and at the rear with the linear actuator 50 by way of the screw 52.

In practice it has been found that the invention fully achieves the intended aim and objects.

In particular, with the invention a Cartesian machine tool has been devised that is capable of restoring the correct configuration of a machining head, without deforming the sliding guides of the slide, and in general without introducing deformations into the means of guiding the movable elements of the machine.

In particular, with the machine 10 according to the invention, the endless screw 52 of the endless screw 52 - lead screw 51 system is not affected by deformations, thus avoiding both irregularity of motion and the occurrence of abnormal stresses that might compromise the reliability of the machine 10.

What is more, with the invention a Cartesian machine tool has been devised in which the position of the machining head can be rapidly corrected with respect to any deviations with respect to a preset position.

Furthermore, with the invention a Cartesian machine tool has been devised with operational performance levels that are not lower than conventional Cartesian machine tools.

Furthermore, with the invention a suitable slide carriage for Cartesian machine tools has been devised.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements. In practice the components and the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

The disclosures in Italian Patent Application No. 102016000027890 (UA2016A001753) from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.