Technical field

The present invention concerns a vertical lathe, having the characteristics declared in the preamble to the principal claim no. 1.

Technological background

In the technical field of mechanical processing on the machine tool for the removal of swarf, and in particular in the field of machine tools for turning, vertical lathes are known, in which the workpiece to be machined is located on a table or chuck rotating about a vertical axis, and in which the tool-bearing slide or carriage is slidably mounted on a horizontal guide or crosspiece which is also capable of vertical movement of raising/lowering with respect to the chuck. By means of the movement of the carriage in the two aforementioned directions, the tool is conveyed along the surfaces of the workpiece being machined (locked to the workpiece-carrying chuck) in accordance with the specified stages of machining.

This configuration, though advantageous due to the fact that the chuck is provided low down and therefore in favour of gravity with respect to the workpieces being machined which are intended to be mounted on said chuck, requires nevertheless a guide structure for the tool-bearing carriage along two axes, with consequent bulk and tools in cantilever with respect to the stationary structure of the lathe. Since lathe tools of the latest generation entail ever- increasing cutting and rotation speeds, the use of such tools requires corresponding ever-greater characteristics of rigidity in the structure of the lathe, characteristics which conflict with the dimensions and extensions in cantilever imposed by the traditional configuration of vertical lathes of known type mentioned above.

Description of the invention

A principal object of the invention is to make available a vertical lathe, structurally and functionally designed for obviating the limitations emphasised above with reference to the known art, and in particular directed at allowing the structure of the lathe adequate rigidity, with limited and compact overall dimensions, limiting as far as possible the distances of the cantilevered loads relative to the tools conveyed over the cutting trajectories required in the turning cycles, at the same time making it possible to use tools of the latest generation designed for high chuck speeds.

This and other objects which will appear clearly in what follows are achieved by the invention by means of a vertical lathe, constructed in accordance with the claims below.

Brief description of the drawings

Further characteristics and advantages of the invention will appear more clearly from the detailed description which follows of a preferred embodiment thereof illustrated, in indicative and non-limiting fashion, with reference to the attached drawings, in which :

figure 1 is a schematic view in side elevation of a vertical lathe according to the invention,

figure 2 is a schematic view in front elevation of the lathe of figure 1, figure 3 is a schematic view on plan from above of the lathe of the previous figures, figures 4 and 5 are views, respectively in side elevation and on plan from above of the lathe of the previous figures, provided furthermore with a device for automatically changing the chuck.

Preferred method of implementing the invention

With reference to the mentioned figures, 1 comprehensively indicates a machine tool designed as a vertical lathe, for performing lathework with vertical movements of the tool, constructed in accordance with the present invention. The lathe 1, only schematically depicted, comprises a workpiece-carrying chuck 2 rotating about a principal axis Z, configured for rotating the workpiece during the mechanical processing. The axis of rotation Z is directed "vertically" if referred to a support plane for the lathe on the ground, schematically illustrated in the figures and marked T.

The chuck 2 is designed as an electro-chuck for machining or positioning and is rotated about axis Z by an electric motor coupled to it. The term "chuck" is therefore intended to refer in the present context to the particular structure and function of electro-chuck, mentioned above.

The chuck 2 is provided with a self-centring device, itself conventional, for locking the workpiece in a centred condition with respect to axis Z. In accordance with a first innovative aspect of the invention, the chuck 2 is furthermore mounted on a slide 3, slidably guided in a direction transverse to axis Z, by means of a pair of guides and against counter-guides 4, 5 respectively secured to a stationary structure 6 of the lathe and to the slide 3, which are capable of mutual sliding engagement. Said guides and counter-guides 4, 5 are extended in a spaced-apart relationship and parallel to a direction X which extends perpendicularly to axis Z, as clearly illustrated in the figures.

In more detail, the two guides 4 are mounted on a surface portion of the stationary structure 6 which rises vertically with respect to the horizontal support plane of the lathe on the ground T, in accordance with a configuration in which the perpendicular projections of the guides 4 on this plane overlap each other, as is also clearly apparent from figure 1.

Conveniently the counter-guides 5 comprise six sliding pads (three pads for each counter-guide 5), of which two pads, indicated by 21 in figure 2 (the pad in the intermediate position along each counter-guide 5), are designed as braking pads for locking the chuck when work is in progress, this feature tending to benefit rigidity in the system in high-speed machining, in particular in machining workpieces in cantilever (i.e. with unbalanced workpieces such as for example when machining brake drums).

The lathe 1 comprises furthermore a tool-bearing carriage 7, which is operatively associated with the chuck 2, and located above the latter with respect to the vertical direction Z and capable of being movably guided from and towards the chuck 2 to bring one or more tools 8, mounted on the carriage 7, into the working area of the workpiece that is to be turned. It should be noted that the configuration with a single tool 8 makes it possible to obtain advantageously, in the working area, the maximum access to the workpiece being machined. The tool-bearing carriage 7 is movable exclusively along a direction (identified by axis Y), oriented parallel to axis Z, and perpendicular to the horizontal direction X.

9, 10 indicate guides and counter-guides, themselves conventional, in mutual sliding engagement, respectively fixed to a portion of the stationary structure 6 and to the carriage 7, to vertically guide the latter, said guides extending in a spaced-apart relationship and parallel to the direction of axis Y, as clearly illustrated in the figures, so as to allow the carriage 7 to be moved exclusively along the direction of axis Y, from and towards the working area close to the chuck 2.

The guides 9 are mounted on a surface portion of the stationary structure 6 which is erected vertically with respect to the horizontal support plane of the lathe on the ground T. Said guides are furthermore located at the top of the area in which guides 4 are located. In a preferred configuration, guides 9 and guides 4 are arranged substantially in the same plane oriented perpendicularly to the support plane T or in respective and distinct planes, parallel and close to each other, and oriented perpendicularly to the support plane T, as clearly emerges from figure 1.

A tool-bearing member 11 is provided on the carriage 7, configured for securing the tool 8, in a configuration particularly designed for machining by turning. It can equally be provided for a tool-bearing member 11 to be securable to the carriage, and also to be endowed with rotating movement, to effect possible drilling operations, besides turning operations.

Axis Y corresponds, more particularly, to the axis of extension of the tool- bearing member or support 11 (in the case, for example, of turning tools), i.e. to the principal axis of extension of the tool itself (in the case of tools for drilling, boring, milling etc.). In the case of a member or support with predominantly longitudinal extension, axis Y thus corresponds to the principal axis of longitudinal extension of the member or support. Axis Y can also be fixed (turning) or rotating (drilling, boring, milling etc.).

According to a principal feature of the lathe according to the present invention, therefore, the tool-bearing carriage 7 is movable exclusively along a direction parallel to the direction of the axis of rotation Z of the electro-chuck 2, and the workpiece-holding electro-chuck 2 is movable transversely to the direction of movement of the carriage 7, exclusively along a direction X perpendicular to the axis of rotation Z of the electro-chuck, and in such a way that the principal axis Y of the tool-bearing member 11 remains always coplanar with the plane described by the axis of rotation Z of the electro-chuck 2 in its movement along the direction X of transverse movement.

It should be noted that the provision of guiding the carriage 7 exclusively along the sole direction parallel to axis Z, with coplanarity between axis Y and the plane described by axis Z in the course along the direction of axis X, requires the space for a single pair of guides and counter-guides 9, 10 with significant containment of the distance D, indicated in figure 1, which identifies the cantilever of the tool 8 with respect to the stationary structure of the lathe, if compared with known solutions in which two orders of guides and counter-guides are specified for conducting the carriage along two perpendicular directions. The degree of freedom removed from the tool-bearing carriage 7, compared with the known solutions, is recovered in effecting the transverse movement (along axis X) of the electro-chuck 2 provided in the lathe of the present invention.

15 indicates a magazine of tools 8, fixed solidly to the stationary structure of the lathe, the magazine being configured for interacting automatically with the tool- bearing member 11, in order to allow automatic changes of tool. In other words, the tool 8 on the member 11 can be exchanged or replaced automatically with another tool 8 in the magazine 15.

A preferred configuration can provide for a device 16 with an exchanger arm 16a carrying gripping means 17, 18 for the tool, which is rotatably supported to present one or the other of the gripping means respectively near the magazine or near the tool-bearing member 11, in order to move a new tool from the magazine towards the tool-bearing member of the carriage and simultaneously move the worn tool connected to the carriage towards the magazine, for the automatic unloading of said worn tool. A preferred choice can provide for a magazine 15 with twenty-four tools movable along two Cartesian axes for preparing tool 8 on the exchanger arm 16a.

In the magazine 15 an optional stage can furthermore be provided, of loading/unloading tools to replace worn tools with new tools, for example in groups of five tools at a time.

A further advantageous aspect connected with the structure of the lathe according to the invention lies in the fact that the loading and unloading of workpieces with respect to the chuck can take place in the same area, located on the same side with respect to the chuck and made suitably accessible by means of a lateral movement, in the direction X, of the chuck itself. A common line can therefore be situated in this area for transfer means for the workpieces, in order to allow the loading of workpieces for machining and the unloading of machined workpieces to take place in said area. This lateral loading/unloading area can furthermore be chosen at a suitable distance from the tool-bearing carriage, thanks to the transverse mobility of the chuck, thus avoiding both the problems of possible interference between the respective areas of activation, and the problems inherent in the known solutions (connected for example with loads in movement, with interference between moving parts, with trajectories and space required, etc.), where the tool-bearing carriage is set up with gripping members for workpieces for loading and unloading said workpieces.

Another advantageous aspect of the invention is connected with the fact that the lathe described above lends itself easily to being coupled with devices designed for changing the self-centring mechanism of the chuck, if there should be a need during the turning cycle to arrange a change of "type" for workpieces for turning. In other words, with reference to figures 4 and 5, in the area for loading/unloading workpieces (indicated by S), for example involving a doorway or similar structure for transferring workpieces, located at the side or the front of the lathe and easily accessible by the movable chuck along the transverse direction X, there can be connected a device 20 for changing the self-centring mechanism, in which the self-centring mechanism on the chuck 2 is removed and automatically replaced by another previously-equipped self-centring mechanism in the device 20. A preferred configuration provides for the use of an exchanging arm 20a, rotatably supported around a vertical direction, for executing, by means of angular rotations of 180°, the operations of automatic changing of the self-centring mechanism.

The invention thus achieves the proposed objects, bringing about the numerous declared advantages by comparison with the known solutions. To sum up, there is the advantage of creating a lathe structure of limited bulk, simple in structural components but of high rigidity so as to permit the use of turning tools even at high speed. Also to be counted, by comparison with known solutions, is improved tool changing and improved loading/unloading of workpieces. Improved flexibility should also be counted, of the stage of changing the self-centring mechanism of the chuck for turning batches of workpieces to be machined dimensionally different from each other.

Yet another advantage is the high degree of access to the workpiece being machined in the work area, access which is maximized in the case of a single tool set up on the tool-bearing slide.

Finally, the high flexibility should be noted of the machine tool according to the invention, thanks to the configuration specified with fixed turning tool and/or with rotating tool for machining including drilling.