In order to carry out ever more complex working operations in ever briefer time intervals, known work centres are equipped with multispindle heads provided with a plurality of tools suitable for carrying out rapidly a plurality of working operations on a piece.

Examples of work centres provided with these known heads are given in EP-A-1132171, EP-A-1055485, EP-A1258314 and EP-A-1260306.

Despite the good results, the known work centres, and in particular the known working heads, are still unsatisfactory from many points of view. The most important unsatisfactory aspect of the known arrangements is the fact that the current multispindle heads are very bulky.

This last aspect makes the positioning of the workpieces on the worktable laborious in a case where it is necessary to carry out working operations on the sides or ends of the pieces and also working operations with undercuts. In fact, in this case, in order to avoid

exposing the spindles, especially the spindles placed below the head, and the tools disposed thereon to collisions with the components of the work centre, it is necessary to place the workpieces at a distance therefrom, making it necessary to use complex bracketing systems which, however, do not avoid the necessity of having to leave the workpieces in conditions of excessive pliability which may lead to working operations with results that are not desired and that are in any case difficult to foresee.

The problem on which the present invention is based is to propose a head of a work centre for working wood pieces, and also a work centre which is provided with such a head and which has structural and functional characteristics such as to overcome the above-mentioned disadvantages discussed with reference to the prior art.

This problem is solved by a work centre head of the type specified above, as defined in claim 1, and also by a work centre as defined in claim 26.

Further characteristics and the advantages of the head and of the work centre according to the invention will emerge from the following description of preferred embodiments thereof which are given by way of non-limiting example with reference to the appended drawings in which: Figure 1 is a first perspective view of a work centre head;

'Figure 2 is a second perspective view of the head of Figure 1; Figure 3 is a side view of the head of Figure 1; Figure 4 is a diagrammatic perspective view of a first arrangement of the spindles in a head according to one embodiment; Figure 5 is a diagrammatic perspective view of a second arrangement of the spindles in a head according to one embodiment; Figure 6 is a diagrammatic perspective view of a third arrangement of the spindles in a head according to one embodiment ; Figure 7 is a diagrammatic perspective view of a fourth arrangement of the spindles in a head according to one embodiment ; Figure 8 is a first perspective view of a work centre according to one embodiment; Figure 9 is a second perspective view of the work centre of Figure 8; Figure 10 is a side view of the work centre of Figure 8.

A description is given hereinafter of a work centre head, and also of a work centre provided with such a head in accordance with various embodiments. In all of these embodiments, the portion of the head or of its devices or

components, and also the portion of the work centre placed at the top of the drawings are referred to as"above"or "top", and likewise the portion of the head or of its devices or components, and also the portion of the work centre placed at the bottom of the drawings are referred to as"below"or"bottom"."Vertical direction"means a direction oriented from"below"to"above"in the drawings and vice versa.

With reference to the above-mentioned drawings, 20 generally indicates a head of a work centre, which is generally indicated 26, for working wood pieces 27.

According to one embodiment, the head 20 comprises at least one first spindle 21 suitable for cooperating with at least two tools 22 and 23 which are arranged in opposite directions to one another and which are substantially aligned along the same axis of the first spindle f-f.

The head also comprises a head body 24 supporting the first spindle 21. The head also comprises a support element 25 suitable for operatively connecting the head 20 to the work centre 26. The support element 25 supports the head body 24 in such a manner that it is rotatable about a head axis A-A or axis of rotation of the head.

Advantageously, the axis of the first spindle f-f (or more simply the axis f) is tangential to a circle g having

its centre 28 on the axis of rotation A-A of the head (Figure 2 and Figures 4 to 7).

In other words, the axis of the spindle f-f and the head axis A-A are located in planes p and q that are separate from and parallel with one another (Figure 1).

The definition of a first spindle 21 suitable for cooperating with at least two tools 22 and 23, according to a further embodiment, is also intended to mean a pair of spindles which have axes f-f coinciding with or aligned with one another and which are suitable for cooperating, on opposite sides, with tools for working pieces. In other words, it also means two spindles aligned on the same spindle axis-f-f.

According to one embodiment, the head comprises at least one second spindle 29 (30 3 ). The at least one second spindle 29 and/or 30 and/or 31 is suitable for accommodating at least one tool 32 and/or 33 and/or 34 directed in accordance with a spindle axis h and/or i and/or 1.

According to one embodiment, the at least one second spindle 29 and/or 30 and/or 31 has a spindle axis h and/or i and/or 1 directed in a direction intersecting the axis of rotation A-A of the head, for example, intersecting at the point forming the centre 28 of the circle g to which the axis f of the at least one first spindle 21 is

tangential.

According to one embodiment, the at least one second spindle 29 and/or 30 has an axis h and/or i directed in a direction at right-angles to the axis f of the at least one first spindle 21 (Figures 4,6 and 7).

According to a further embodiment, the at least one second spindle 29 and/or 30 has an axis h and/or i which forms an angle of 45° with respect to the axis f of the at least one first spindle 21 (Figure 5).

For example, the head 20 comprises two second spindles 29 and 30 having an axis h and i which forms an angle a and b of 45° with respect to the axis f of the at least one first spindle 21.

According to one embodiment, the head comprises three second spindles 29, 30 and 31 having an axis h, i and 1 intersecting the axis of rotation A-A of the head, for example, intersecting at the point forming the centre 28 of the circle g to which the axis f of the at least one first spindle 21 is tangential.

According to a further embodiment, two of the second spindles 29 and 31 have parallel axes h and 1 and the third of the second spindles 30 has an axis i at right- angles to the first two second spindles 29 and 30 (Figures 4 and 7).

Particularly advantageously, the head 20 comprises a

plurality of spindles 21,29, 30 and 31 arranged with axes f, h, i and 1 coplanar with one another.

According to a particular embodiment, at least one second spindle 29 and/or 30 and/or 31 has an axis h and/or i and/or 1 in a plane which is separate from and parallel with a plane n containing the axis of rotation A-A of the head. Advantageously, the at least one second spindle 29 and/or 30 and/or 31 has an axis h and/or i and/or 1 tangential to a circle m having its centre 28 on the axis of rotation A-A of the head (Figure 7).

According to one embodiment, the head comprises at least two, and advantageously three, second spindles 29 and/or 30 and/or 31 having a spindle axis h and/or i and/or 1 tangential to a circle m having its centre on the of rotation A-A of the head (Figure 7).

According to a preferred embodiment, the head comprises four spindles 21,29, 30 and 31 which are advantageously suitable for cooperating with at least five tools 22,23, 32,33 and 34.

According to a further embodiment, the at least one first 21 and second 29 and/or 31 spindle have spindle axes f, h and 1 which are parallel with one another (Figures 4 and 7).

According to yet another embodiment, at least two of the at least one first 21 and second 29 and/or 30 spindle

have spindle axes f, i and/or h at right-angles to one another (Figures 4,7 and 6).

Advantageously, the support element 25 of the head comprises a fork provided with at least one prong 35 or 36. The fork 25 is suitable for supporting the rotating body 24 of the head 20 by means of its at least one prong 35 or 36.

According to one embodiment, the fork 25 is provided with at least two prongs 35 and 36 between which the head body 24 is supported in such a manner that it is pivotable about the axis of rotation A-A of the head. For example, the head body 24 is movable about the head axis A-A in a controlled manner. In particular, the head body 24 is operatively associated with means for controlled and retroactuated drive for pivoting it about the head axis.

According to an alternative embodiment, at least one of the at least one first and second spindle 21, 29,30, 31 is supported on the head body 24 in such a manner that it is pivotable or rotatable about a spindle pivot axis D.

For this reason, the at least one of the at least one first and second spindle 21, 29 ; 30,31 is, for example, operatively associated with means for controlled and retroactuated drive for pivoting it about the spindle pivot axis D, in the manner which will be described in more detail hereinafter.

The support element 25 is, for example, connectable to the work centre 26 for working wood pieces in such a manner that it is pivotable about a second head axis, or axis C. Advantageously, the second head axis C is arranged at right-angles to the head axis A-A or first head axis A.

According to one embodiment, the at least one of the head axis A and the second head axis C is operatively associated with means for controlled and retroactuated drive for a controlled pivoting or rotation of the head body 24 and the support element 25, respectively, relative to the means for moving the work centre head, in the manner which will be described in more detail hereinafter.

As can be seen from Figures 8, 9 and 10, the work centre 26 for working wood pieces comprises at least one head 20 provided with at least one spindle 21 and/or 29 and/or 30 and/or 31.

According to one embodiment, the head 20 is supported on means 38 and 39 for moving it relative to the workpiece 27, this movement being preferably of the controlled type, along at least two axes X, Z, which are preferably at right-angles to one another.

Advantageously, the head 20 is supported on means 38, 39 and 40 for the controlled movement thereof, relative to the workpiece 27, along at least three axes X, Y, Z which are, for example, at right-angles to one another.

In particular, the work centre 26 comprises at least one worktable 41 which is pivotable or rotatable about a table axis B.

According to one embodiment, the head 20 is supported by a first carriage 38 supported to be movable in accordance with a first direction, or axis Z, on a second carriage 39 which is in turn movable in accordance with a second direction, . or axis. X, which is advantageously at right-angles to the first direction Z. The first and second carriage 38 and 39 are movably supported by a cross-member 42 of a portal structure 43 in such a manner as to move the head 20 into a work space located above and to the side of at least one worktable 41 suitable for supporting at least one workpiece 27. The portal structure 43, supporting the carriages 38 and 39 and the head 20, is arranged in such a manner that it straddles a bench 44 which supports at least one worktable 41 movable in a controlled manner along the axis Y.

Preferably, the bench supports at least two worktables 41, which are movable independently of one another and in a controlled manner along the axis Y, preferably by means of movement means which are independent of one another. According to one embodiment, the worktables 41 are supported on the bench by way of carriages 40 and are supported on those carriages in such

a manner that they are pivotable about a table axis B.

Advantageously, at least one of the worktables 41 is supported on the bench 44 by means of a carriage 40 which is movable along an axis Y and which projects in a cantilevered manner from the bench 44.

At least one of the above-described axes of movement X, Y, Z, B comprises means for controlled and retroactuated drive as will be described hereinafter.

According to one embodiment, the work centre is provided with a numerical control (shown diagrammatically in Figure 8 by means of the box 37) which is operatively connected to a drive device suitable for controlling at least one motor, for example an electrical motor, in particular of the brushless type, which is connected operatively to a transmission, for example, at least one recirculating screw, in particular of the type with recirculating ball thread, the nut of which is connected to the movable member having a translation axis (for example the axis X, Y, Z). In a case where the axis is an axis of rotation (such as the axes A, C, B and optionally D), the transmission advantageously comprises pulleys, one of which is keyed to the shaft of the motor, and which pulleys are connected operatively by belts, for example toothed belts. According to one embodiment, the axis (X, Y, Z) comprises at least one carriage or table supported

on guides, for example, recirculating guides, in particular with recirculating ball thread or rollers, preferably of the preloaded type, in order to limit any play of the carriage or the table transverse to the axis.

The axes (X, Y, Z, A, B, C and optionally D) are advantageously provided with sensors that are suitable for detecting the position of the moving members, for example, the carriages, or the angular position of the head body, the table or the at least one spindle, and that are necessary for the retroactuation of the drive. In particular, any retroactuation of the control is ensured, for example, by sensors which are of the linear or rotary type, depending on the axis, and which are operatively associated with the moving member and connected to the control device in order to provide by analogue or even digital means a signal which is proportional to the movement of the axis to be retroactuated.

As will be appreciated from the above description, the head and the work centre according to the present invention make it possible to satisfy the above-mentioned requirement of limiting bulkiness, without any need to limit the working operations that can be carried out by the head or by the work centre.

In addition, owing to the solutions proposed, it is possible to arrange the head very close to the bench or to

the table in order to work the sides or the surfaces of the pieces which are more remote or which are undercut.

The head and the work centre provided with the head are also particularly versatile. With a few rapid positioning movements, it is possible to carry out a multiplicity of working operations, even when the workpiece is at a distance from the plane of the worktable or from the bench that is shorter than the longitudinal extent of a spindle.

In addition, in a case where the first spindle, with two tools having an axis f. tangential to the circle that has its centre on the axis of rotation A-A of the head, is flanked by at least one second spindle, the proposed head makes it possible to use in the same working cycle a large number of tools which are possibly fitted together to carry out various working operations with a single placement of the piece.

A further advantage of the head and the work centre according to the invention resides in the unusual structural simplicity thereof which enables them to be produced at a very small cost.

It will be appreciated that it is possible to vary and/or add to what has been described and illustrated above.

For the purpose of satisfying contingent and specific requirements, a person skilled in the art may introduce to

the preferred embodiments of the head and the work centre described above numerous modifications, adaptations and replacements of elements by other functionally equivalent elements, without, however, departing from the scope of the following claims.