WO2008004263A2

WO2008004263A2 - Machining centre with positioning system of the workpiece clamping members

Info

Publication number: WO2008004263A2
Application number: PCT/IT2007/000451
Authority: WO
Inventors: Alberto Ruggieri
Original assignee: Paolino Bacci S.R.L.
Priority date: 2006-07-05
Filing date: 2007-06-26
Publication date: 2008-01-10
Also published as: ITFI20060170A1; WO2008004263A3; EP2035184A2

Abstract

The machining centre comprises a tool head (9, 9A) and at least one support (15) for workpieces to be machined (P). The support (15) is movable along at least a first numerically controlled axis and is provided with a plurality of clamping members (19) adjustable in variable positions along at least one direction of adjustment, substantially parallel to one of the numerically controlled axes of translation. There are also provided stop devices to fasten the clamping members in the desired position along a direction of adjustment. To perform adjustment there is provided a temporary constraining element (23, 23A) associated with a load bearing structure (21; 11) to temporarily constrain the clamping members (19) to the structure. The support (15) and the structure (21, 11) are reciprocally movable with a numerically controlled movement to adjust the clamping members.

Description

Machining centre with positioning system of the workpiece clamping members

DESCRIPTION Technical field

The present invention relates to improvements to machining centres or machine tools, in particular - although not exclusively - for machining workpieces made of wood, plastic, light alloys, aluminium, composite materials or the like. State of the art

Within the scope of the present description and of the appended claims, machining centre or machine tool is intended in general as an aggregate of mechanical components organized and controlled to perform chip removal machining for on workpieces. A machining centre will therefore generically be provided with a tool head or machining head, with one or more spindles, and with one or more supports for the workpieces to be machined. The support and the head are movable with respect to each other according to a plurality of numerically controlled axes. Unless otherwise specified, the relative movement can be obtained by making one or other or both of the two components movable with respect to a fixed system of reference.

Numerically controlled axis is intended generically as a system that imparts a translational movement in one direction in space or an oscillatory or rotational movement about an axis of oscillation or rotation, under the control of a program and with the use of a drive and of a servo motor.

To machine workpieces of various shapes, numerically controlled machining centres are provided with supports for the workpieces, which are clamped on the supports using clamping members. These members can directly clamp the workpieces to be machined, or fixtures designed to carry these workpieces. In general, to clamp workpieces of different shapes adjustable clamping members, which can be adapted to the shape of the workpieces or of the fixtures to be clamped each time, must be provided. The supports with the clamping members are also used for referencing of the workpieces to be machined with respect to one or more reference surfaces, i.e. to take them to a specific position in space, to which the machining positions are referred.

Machining centres are known, which are provided with workpiece supports in the form of tables, for example, but not necessarily horizontal and flat, which have variable dimensions, i.e. adjustable in at least one direction, to adapt to the dimension of the workpieces to be machined. An example of a machining centre with a supporting surface for workpieces with variable dimensions is described in EP-A-873817.

The tables can carry manual or automatic clamping systems. When a limited series of workpieces must be machined, i.e. when limited batches of identical workpieces must be produced, frequent operations to adjust the workpiece clamping members are required, resulting in a high incidence of skilled workers and extensive machine downtime, both factors resulting in an increase in machining costs and therefore in the cost of the finished workpiece.

It is therefore important to reduce set-up times, i.e. to position and configure the supports and the clamping members at each machining cycle of a specific production batch.

Therefore, systems have been produced for positioning the workpiece supports on a horizontal plane, which make use of position transducers or also motorized systems or actual numerically controlled systems (EP-A- 1055485). These systems allow a high level of automation of the set-up phase of machining centres but imply high machine costs, due to the use of a noteworthy number of complex and costly components, in particular when the number of members to be set up is considerable.

US-A-5, 700,117 describes a machine for machining wooden panels by means of an operating head to carry tools, movable along numerically controlled axes of translation in a horizontal plane. The panels to be machined are clamped on a bench by means of clamping elements, e.g. of the suction type, which must be previously positioned in appropriate points as a function of the dimension and shape of the panel. For this purpose the clamping members are movable on a guide system with a cross arrangement, i.e. a system of guides that allow movement of the clamping members along two orthogonal horizontal axes of adjustment. Movements are performed directly by the tool head, which for this purpose has an extractable rod, which engages selectively in holes associated with one or other of the various clamping members to be positioned. The servo motors that move the head along the two numerically controlled orthogonal axes are, therefore, in this case also used to position the single clamping members. To detect the position of the clamping members specific position sensors are used that determine the position of the various members. This known machine has some drawbacks, both from the viewpoint of costs, which in any case remain high due to the need to provide position sensors, and from the viewpoint of reliability, as the translational and positioning movement is performed using the tool head. This circumstance is particularly disadvantageous, as any resistance to the movement, for example due to the presence of debris on the sliding guides, causes the occurrence of even noteworthy mechanical stresses on the head, according to multiple possible variously oriented directions in the horizontal plane. This leads to risks of deformations in the mechanical supporting structure of the head and in any case inaccuracies in machining precision. Moreover, this known machine is designed solely to machine panels and therefore the configuration of the positioning systems of the clamping members is not suitable for example for machines designed to machine elongated beam-shaped (such as chair legs) or shell-shaped workpieces. Objects and summary of the invention

According to a specific aspect, an object of a possible embodiment of the present invention is to provide a machining centre or machine tool in which it is possible to reliably and rapidly adjust the workpiece clamping members or the fixture clamping members, using systems that have a low incidence on the overall costs of the machine.

According to a different aspect, an object of an embodiment of the invention is to provide a machining centre that allows positioning, i.e. adjustment, of the clamping members with high precision without the need to use further servo motors, controlled axes, or transducers with respect to those normally required to perform machining of workpieces according to the numerically controlled axes already provided on the machine.

In a possible embodiment of the invention, a machining centre or machine tool is provided, comprising a tool head and at least one support for the workpieces to be machined, provided with a plurality of adjustable clamping members, where the head and the support are movable with respect to each other along a plurality of numerically controlled axes of translation, and wherein:

- the support is movable along at least a first numerically controlled axis, typically a horizontal axis of translation, and is provided with a plurality of clamping members adjustable in variable positions along at least one direction of adjustment, substantially parallel to one of the numerically controlled axes of translation, stop devices being provided to fasten said clamping members in the desired position along said direction of adjustment;

- a temporary constraining element associated with a load bearing structure is provided to temporarily and selectively constrain the clamping members to said structure, said clamping members being configured to be temporarily constrained to said constraining element; - the structure with which the temporary constraining element is associated and the support are reciprocally movable with a numerically controlled movement to adjust the clamping members along the direction of adjustment.

Advantageously, in a preferred embodiment of the invention, the reciprocal movement between the structure and the support, to perform adjustment of the clamping members, is controlled along one of the numerically controlled axes with which the machine or machining centre is provided to perform machining of the workpieces, to avoid the need for further controlled axes and further transducers or position sensors with respect to those already provided for the machining operations that can be performed with the machining centre.

Preferably, the head is movable along at least a second numerically controlled axis. In general, the machining centre will preferably have a plurality of numerically controlled axes of translation, typically three axes, and one or more axes of oscillation or rotation, also controlled numerically. These numerically controlled movements will be allocated in part to the head and in part to the workpiece support. For example, the head will be provided with oscillatory or rotational movements about one or preferably two numerically controlled axes. The translational movement along a vertical axis is usually, but not necessarily, allocated to the head, while a further two numerically controlled translational movements, along two substantially horizontal directions preferably approximately orthogonal to each other will be allocated to the support. However, it must be understood that allocation of the movements to one (head) or other (support) of the components is not necessarily binding although these are preferred configurations, also as a function of the type of machining to be performed by the machining centre.

According to an advantageous embodiment, the direction of adjustment is a substantially horizontal direction. However, according to a particular embodiment, the adjustment movement can be along a vertical axis, or along more than one axis, which can be both horizontal and vertical. The adjustment movement can also take place along two axes preferably orthogonal to each other, which are carried in a horizontal plane, so that the adjustment movement always takes place in a horizontal direction, while during machining the support member could be oriented differently with respect to the orientation taken in the adjustment step. Preferably, when two directions of adjustment are provided, one of the two is a direction which - during machining of the workpiece - is oriented vertically, and adjustment along this direction allows the clamping members to be positioned at different heights, to allow clamping of a workpiece of complex shape, which must therefore be held using clamping members adjusted at different heights.

In an advantageous embodiment of the invention, the direction of adjustment is substantially parallel to a numerically controlled axis of translation of the head. In a different embodiment, the direction of adjustment is substantially parallel to a numerically controlled axis of translation of said support.

Numerically controlled axis of translation is intended as an axis defining a direction in space, along which one of the components (i.e. the head or the support) of the machining centre performs movements under the control of a numerically controlled drive of a programmable unit.

In a possible embodiment, the head is provided with a movement according to at least one numerically controlled axis with respect to said temporary constraining element.

According to a possible embodiment, the support is movable along a first numerically controlled axis, to move reciprocally towards and away from the clamping members and the temporary constraining element. For example, in this case the structure with which the temporary constraining element is associated can be an upright, on which the head is supported. The support and the upright are in this case provided with a reciprocal movement towards and away from each other, preferably a numerically controlled movement along a respective horizontal axis of translation. The head can be supported on the upright with a translational movement of its own, for example along a numerically controlled axis in a vertical direction. In a possible embodiment, the upright is fixed, for example carried by a fixed base and the support is provided with a first movement towards and away from said upright and with a second translational movement substantially parallel to said direction of adjustment. Preferably, the two movements of the support are performed along numerically controlled axes of translation.

In a modified embodiment, the upright is movable along a numerically controlled axis of translation and the direction of adjustment is substantially parallel to said axis of translation along which the upright is movable. In this case positioning of the clamping members is performed by the upright when it translates along the direction of adjustment. As in this case the upright preferably carries the head, in turn movable vertically on the upright, positioning, i.e. adjustment of the clamping members is performed making use of one of the numerically controlled translational movements with which the head is provided. Nonetheless, contrary to the case of the aforesaid known systems, the head is not stressed, as the clamping members are temporarily constrained to the upright, rather than to the head.

In a different embodiment, the support is movable along a first guide substantially parallel to said first numerically controlled axis and to said direction of adjustment, and a second guide substantially parallel to said first guide and along which said clamping members are adjustable is constrained to the support. In this case, according to a particularly advantageous embodiment, the first guide is carried by the structure with which the temporary constraining element is associated. For example, the structure carrying the temporary constraining element can be formed of or integral with a base with which the sliding guide of the support is integral.

In a possible embodiment of the invention, the first guide on which the support slides is produced on a carriage which is in turn movable along a third guide not parallel to the first and to the second guide, to allow the clamping members to move towards and away from the load-bearing structure with which said temporary constraining element is associated. In substance, the first and the third guide form a guide system with a cross arrangement, for movement according to two Cartesian axes typically lying in a horizontal plane and numerically controlled, for movement of the support of the workpieces to be machined.

Instead of on an upright, the tool head can be carried by a gantry. According to a possible embodiment, below said gantry there extends a fixed structure carrying the temporary constraining element, and associated with which is a sliding guide for the support. Preferably, the movement of the support along the guide can be a numerically controlled movement. Advantageously, according to a possible embodiment the support is provided with an adjustment guide substantially parallel to said sliding guide and on which said clamping members are adjustable.

In a possible embodiment, the machining centre is provided with a control unit of the movements along the numerically controlled axes, programmed to store the positions of the clamping members and perform adjustment and/or positioning of the clamping members on the basis of stored information concerning the position of said clamping members, thereby avoiding the need to use auxiliary position sensors or transducers. In a more complex embodiment, the clamping members are also adjustable along a second direction of adjustment, not parallel to the first direction of adjustment and preferably approximately orthogonal to the first direction of adjustment. According to a possible embodiment, the second direction of adjustment is substantially vertical. When adjustments, i.e. positionings along two directions of adjustment, are to be made, an advantageous embodiment of the invention provides for a control unit of the movements along the numerically controlled axes programmed to perform positioning or adjustment of the clamping members sequentially first along one of the directions of adjustment and subsequently along the other of the directions of adjustment.

In an advantageous embodiment, adjustment or positioning along the second direction of adjustment is performed by interaction between the head and the clamping elements, the final position of the clamping elements being defined by means of the numerically controlled position of the head along a numerically controlled axis substantially parallel to the second direction of adjustment. In a possible embodiment, the head is provided with a movement along at least two numerically controlled axes of translation not parallel to each other, and adjustment of the clamping members along the second direction of adjustment takes place subsequent to adjustment along the first direction of adjustment, for each clamping member to be adjusted the head being positioned along one of said at least two numerically controlled axes of translation to carry a stop integral therewith to the position of the respective clamping member, and the relative clamping member subsequently being made to interact with said stop, the final position of said clamping member being determined by the position of said head along the other of said at least two axes of translation.

Further advantageous features and embodiments of the invention will be described hereunder with reference to some non-limiting examples of embodiment of the invention. Brief description of the drawings

The invention will be better understood by following the description and accompanying drawing, which shows practical non-limiting embodiments of the invention. More specifically, in the drawing: Figure 1 shows a front view of a machining centre or machine tool in a first embodiment of the invention;

Figure 2 shows a plan view according to M-Il in Figure 1 ;

Figure 3 shows a side view according to Ill-Ill in Figure 1 ;

Figure 4 shows a side view of a machining centre according to the invention in a different embodiment;

Figure 5 shows a plan view according to V-V in Figure 4;

Figure 6 shows a side view of a modified embodiment of a machining centre according to the invention;

Figure 7 shows a plan view according to VII-VII in Figure 6; Figure 8 shows a side view of a further embodiment of the invention; Figure 9 shows a front view of a gantry structure of a machining centre according to the invention, in which the machining head has been omitted to facilitate representation; Figure 10 shows a plan view according to X-X in Figure 9;

Figure 11 shows a side view according to Xl-Xl in Figure 10 Detailed description of embodiments of the invention

With initial reference to Figures 1 to 3, a machining centre according to the invention will firstly be described, which has a gantry structure and wherein the clamping members of the workpieces to be machined are adjustable according to two distinct directions of adjustment, one substantially vertical, the other substantially horizontal.

In this embodiment, the machining centre, indicated as a whole with 1 , has a gantry 3 with uprights 3B and a horizontal cross member 3A, along which there are disposed guides 5 for translation of a slide 7 carrying a machining head, i.e. a tool head 9. The tools are indicated by way of example with U and are arranged on four electro spindles carried by the head. The assembly of the four spindles (indicated with M in Figure 3) rotates about a horizontal axis of rotation or oscillation A. The movement about this axis is controlled by a programmable control unit; therefore, this is a numerically controlled axis.

Through the gantry 3, between the uprights 3B and below the cross member 3A, there extends a base 11 on which there are provided two substantially parallel horizontal guides 13, sliding along which are two slides 15 forming supports for the workpieces. The workpieces can be represented for example by elongated elements of chairs or other furniture components. One of these possible workpieces to be machined is indicated with P in Figure 1. Each support 15 can move independently from the other along an axis X which forms a first numerically controlled axis of translation of the machining centre 1. The letters Y and Z indicate a second numerically controlled axis of translation and a third numerically controlled axis of translation. The axes X, Y and Z are substantially orthogonal to one another. The movement on the Y axis is allocated to the head 9 and more precisely to the slide 7 that carries it, movable along the horizontal guide 5 on the cross member 3A. The movement along the vertical axis of translation Z is provided by the head 9 which translates for this purpose on guides 7A provided on the slide 7.

To each of the supports 15 there is rigidly constrained a further substantially horizontal guide 17 having a direction approximately parallel to the guides 13 and consequently parallel to the numerically controlled axis X. On the guides 17 of each support 15 two clamping members 19 can be positioned for clamping the workpiece to be machined. Each clamping member 19 comprises (see in particular Figure 1) a carriage 19A engaged by means of shoes on the guides 17 and having a brake, indicated schematically with 19B, to lock the respective carriage 19A, and consequently the clamping member 19, in a specific position with respect to the guides 17 and consequently to the support 15. During machining of the workpieces the clamping members 19 are held in a pre-established fixed position by activating the brake 19B. The position along the guide 17 of the single clamping members 19 is determined by the shape of the workpiece P to be machined.

This position is adjusted at the start of machining a specific production batch using part of the numerically controlled axes with which the machining centre 1 is provided to perform the chip-removal machining operations on workpieces P. More specifically, adjustment along the guides 17 of the members 19 is performed by making use of the numerically controlled axis X of each of the supports 15. For this purpose, on each side of the base 11 a bracket 21 is fastened, integral with which is a piston-cylinder actuator 23 which forms a temporary constraining element between the load bearing structure formed of the base 11 and one or other of the clamping members 19 disposed on one or other of the guides 17. Constraint is obtained through cooperation between the rod 23A of the piston-cylinder actuator 23 and an element complementary to the rod 23A represented, in this embodiment, by a notch, seat or groove 25 produced on each of the carriages 19A.

In practice, by taking, by translation of the support 15, one or other of the clamping members 19 to the level of the temporary constraining element 23, making the rod 23A of the piston-cylinder actuator 23 penetrate the seat or notch 25, a temporary constraint is obtained between the carriage 19A of the clamping member 19 and the structure carrying the temporary constraining element 23, in this case formed of the base 11. By releasing the brake 19B it is then possible to adjust the position of the clamping member 19 constrained to the temporary constraining element 23 simply by translating the support 15 along the numerically controlled axis X, which will move with respect to the carriage 19A, held still with respect to the base 11. Upon reaching the desired position of the carriage 19A on the respective guide 17, the brake 19B is once again activated to fix this position and the temporary constraining element 23 is deactivated by withdrawing the rod 23A of the piston-cylinder actuator. In this way the clamping member 19 is once again integral with the support 15 having taken, with respect thereto, the new position fixed by the previous adjustment step.

It must be understood that the arrangement of the elements 25, 23 and 23A can be inverted, in the sense that the temporary constraining element integral with the base 11 can be formed of a hole, a notch, a seat or another element analogous to the one indicated with 25, while each of the clamping members 19 carries (in place of the notch 25) an actuator analogous to the one indicated with 23.

From the above it is understood that each of the clamping members 19 (two for each support 15 in the example illustrated) can be adjusted in position with respect to the support 15 using the same numerical control (X axis) with which the machining centre is provided to perform machining of the workpieces. The control unit can store each time the position of the support 15 and of the clamping member 19 with respect to said support so that it is able to perform, before machining of the subsequent batch, the necessary adjustment of the clamping members 19 with the procedure described above.

In the embodiment of the invention shown in Figures 1 to 3 there is also provided a further possible adjustment, in a vertical direction (substantially parallel to the numerically controlled axis Z) of each of the clamping members 19. For this purpose the head 9 has a stop 10 (Figure 1) integral in this example of embodiment with the element or casing 9A bearing the spindles M and rotating about the numerically controlled axis A. This stop is used to perform positioning, i.e. adjustment in the direction Z of each single clamping member 19. According to an advantageous embodiment, this adjustment is performed in succession, i.e. in sequence with respect to adjustment along the axis X of the respective clamping member 19 with respect to the support 15.

In other words, at each machining cycle of a new batch there is first performed adjustment, i.e. positioning of the single clamping members 19 along the guides 17 using the relative temporary constraining element 23. After performing this positioning and storing the relative positions of each of the supports 15 on the one side and clamping members 19 on the other, by means of translation along the axis X of the support 15 each clamping member 19 is carried under the head 9 which has been or is positioned angularly about the numerically controlled axis A to place the stop 10 facing downwards, as shown in Figure 1. After reaching this position it is possible to proceed in one of the modes described below.

According to a first operating mode, the head 9 is carried to a known position along the axis Z and, by means of a piston-cylinder actuator 31 with which each of the clamping members 19 is provided, the vertically movable part indicated with 19C of said clamping member 19 is raised, if necessary until it comes into contact with the stop 10 of the head 9, or in any case to a maximum pre-established height, which can be a height of zero. Having reached this position, the head 9 is gradually lowered, with a numerically controlled movement along the axis Z, pushing the part 19C downwards, acting thereon by means of the stop 10, until the stop 10 reaches the height at which the upper part 19C of the clamping member 19 is to be carried and clamped. The lowering movement of the part 19C can be suitably opposed (to maintain contact with the stop 10), for example by maintaining the piston- cylinder actuator 31 under slight back pressure. The movement is guided along guides indicated schematically with 19D in this embodiment.

After reaching this position, said position is fixed by activating a brake 19E with which the vertically movable part 19C of the clamping member 19 is provided (see Figure 1).

According to a different method of adjustment it is possible in the first place to lower, by means of the piston-cylinder actuator 31 , the vertically movable part 19C of the clamping member 19, then take the stop 10 to the desired height by numerically controlled translation along the axis Z of the head 9. After clamping the head in this position, the part 19C is raised by means of the piston-cylinder actuator 31 with a movement guided along the relative slide-guide system 19D, until reaching the stop 10. Having reached this position the brake 19E is locked to fix the position reached. In any case, by means of the numerically controlled axis Z with which the machining centre 1 is provided to perform the normal machining operations to remove chips, it is possible to adjust the vertical position of each of the clamping members 19, separately from each other. For this purpose the stop 10 is provided with shape and dimensions that allow it to act individually on each of the clamping members 19 (or more precisely on the movable part 19C thereof) without interfering with the others.

Rather than on the spindle element or casing 9A, the stop 10 could also be carried in another position, for example by the head or fork 9 as indicated by the dashed line in Figure 3 and with the reference 10A. In a modified embodiment, the stop 10 can be carried by one or by the other of the spindles M.

Figures 4 and 5 show an embodiment of the invention in a machining centre with a fixed upright. In this embodiment the machining centre 1 has a fixed horizontal base 11 , to which a fixed upright 103 is fastened. It would also be possible for the two elements 11 and 103 to be fixed to a common floor but not constrained directly to each other.

On the upright 103 there are provided guides 7A for sliding of a carriage or slide 7 carrying a head 9, which in this embodiment is formed of a double rotating head, i.e. provided with a movement of oscillation and/or rotation about two distinct numerically controlled axes indicated with A and B. It must be noted that for the purposes of adjustment of the clamping members 19 the head could have a single axis of rotation or oscillation, i.e. could be a single rotating head.

The head 9 in practice has an element 9A rotating about the numerically controlled axis A, in turn supported by a component rotating about the vertical axis B. In this embodiment the element 9A carries the same number of spindles M as there are tools U, although it would also be possible to provide a different number of tools and spindles, as is the case in the example of embodiment shown in the previous Figures 1 to 3. In general, the tools U can be interchangeable and for this purpose the machining centre can have a tool magazine and tool-changing members known per se and not shown.

The base 11 is provided with guides 105 which extend along a direction substantially coincident with a numerically controlled axis Y along which a carriage or slide 121 moves guided on the guides 105. This carriage or slide 121 is provided with guides 113 for a support 15 which, together with the carriage or slide 121 , forms a cross arrangement of slides or carriages, i.e. movable along numerically controlled axes X and Y substantially orthogonal to each other, the axis X being substantially parallel to the guides 113. The support 15 is provided with sliding guides 117 for a plurality of clamping members 19 (three in the example shown in the drawing). Each clamping element or member 19 has a seat, in the form of a notch, hole or the like, indicated with 25, inside which there can be inserted the end of a rod 23A of a piston-cylinder actuator 23 constrained to the upright 105 and forming a temporary constraining element between the structure formed of the upright 103 and one or other of the clamping members 19.

In this embodiment each clamping member 19 has two vertically movable elements indicated with 151 (upper element) and 153 (lower element). The workpiece to be machined is clamped by means of one or more of the clamping members 19 placing it between the elements 151 and 153, which are then closed by moving them reciprocally towards each other and holding therebetween the workpiece to the machined. According to the type of machining to perform one or other of the elements 151 , 153 can serve as a surface of reference and therefore remains fixed in a predetermined position, or is always returned to this position, while the other of the two elements 151 , 153 is movable as a result of a piston-cylinder actuator (not shown) to clamp the workpiece. This clamping carries the workpiece to abut against the element 151 , 153 which serves each time as surface of reference. This arrangement of the clamping elements 151 , 153 is known per se. Adjustment of the clamping members 19 along the first direction of adjustment represented by the guides 117 is performed as follows. The carriage or slide 121 is translated along the numerically controlled axis Y to reach the position indicated with the dashed line in Figure 4. Before, during or after this movement along the axis Y, the support 15 is translated along the numerically controlled axis X until the clamping member 19 that is to be positioned, i.e. adjusted along the guides 117, is in front of the temporary constraining element 23. In this way with a sequence of operations it is possible to engage first one and then the other of the clamping members 19, making the end 23A of the rod of the piston-cylinder actuator 23 penetrate the corresponding seat 25 of the clamping member 19. As in the embodiment in Figures 1 to 3 each clamping member 19 is provided with a brake 19B which is released, i.e. deactivated, when adjustment of the clamping member 19 requires to be performed. Preferably, the brake is released after, with a combined movement along X and along Y, the clamping member 19 to be adjusted has been carried between the structure shared by the upright 103 and the clamping member 19, with the seat 25 engaged with the end 23A of the rod of the piston cylinder actuator 23 forming the temporary constraining element. After this position has been reached and the brake 19B released, the support can translate by means of a numerically controlled movement along the axis X to reach the desired reciprocal position between the support 15 and the clamping member 19. At this point the brake 19B is again activated to fix the reciprocal position reached. The operation is repeated for each of the clamping members 19 to be adjusted along the direction parallel to the numerically controlled axis X, i.e. along the guide 117.

Vertical adjustment, i.e. parallel to the numerically controlled axis Z, is performed by an operation similar to the one described with reference to Figures 1 to 3 and subsequent to the adjustment operation, i.e. to position the clamping elements or members 19 along the axis X and the guides 117. For this purpose, with a movement of the carriage or slide 121 according to the numerically controlled axis Y along the guides 105, each clamping member 19 to be positioned or adjusted in the direction Z is carried under the head 9 and by means of a reciprocal movement between the head and one or other of the elements 151 , 153, with a procedure similar to the one described previously with reference to Figures 1 to 3, the vertical position of the clamping member 19 is adjusted.

In practice, either one or other of the elements 151 , 153, can be adjustable vertically and clamped in the desired position with respect to the support 15. For this purpose two piston-cylinder actuators, or other types of actuators, associated with one and with the other of the elements 151 , 153 and sliding guides for the latter, not shown, are sufficient.

According to the type of adjustment required (i.e. according to which of the two elements 151 , 153 must be carried to a pre-established vertical adjustment position), the head 9 (or more precisely a stop integral therewith and indicated schematically with 10 in Figure 4, indicated here as integral with the spindle casing 9A) is carried to cooperate with one or other of the elements 151 , 153, with a procedure analogous to the one described above for the elements 19C in Figure 1. Alternatively, the stop 10 can be carried by the slide 7, as indicated with a dashed line and with the reference 1OA in Figure 4.

Also in this case the arrangement of the elements 25 and 23, 23A can be inverted, i.e. an actuator can be provided on each of the clamping members 19 and a fixed element on the upright 103. However, the embodiment shown with a single actuator 23 is preferable for obvious reasons of cost. The piston-cylinder actuator 23 and the respective rod 23A could also be replaced by a fixed rod, as the reciprocal engaging movement between the temporary constraining element 23 and the seat 25 is obtained with the numerically controlled movement along the axis Y of the carriage 121.

The embodiment in Figures 6 and 7 shows a machining centre similar to the one shown in Figures 4 and 5. The same numbers indicate the same or equivalent parts to those in the embodiment in Figures 4 and 5. In Figures 6 and 7 however, the upright 103 is not fixed with respect to the base 11, but movable along a numerically controlled axis X, which replaces the numerically controlled axis X in Figures 4 and 5, along which in that case the support 15 was translatable along the guides 113 integral with the carriage or slide 121.

Vice versa, in the embodiment in Figures 6 and 7, the support 15 on which the clamping members 19 are mounted is provided with a single numerically controlled movement along the horizontal axis Y, the numerically controlled translational movement along the axis X being entrusted, as said, to the upright 103.

On the upright 103 there are again provided guides 7A for the slide or carriage 7 carrying the head 9, again rotating about two numerically controlled axes of rotation or oscillation A and B. The number 9A indicates the element carrying the spindles M for the tools U.

The clamping members 19 have a shape substantially equivalent to that of the clamping elements or members 19 in Figures 4 and 5. Adjustment of the single clamping members 19 along the guides 217 parallel to the numerically controlled axis X takes place as follows. The upright 103 is taken approximately to the position of the base 11 and the support 15 is translated according to the axis Y towards the upright 103 until the seat 25 of the clamping member 19 to be adjusted engages with the rod 23A of the piston-cylinder actuator forming the temporary constraining element carried by the structure represented in this case by the moving upright 103. Having reached this position of reciprocal engagement the upright 23 is translated with a numerically controlled movement along the axis X guided by the guides 203 integral with a fixed base 205. Also in this case the adjustment operation takes place for each clamping element or member 19 by releasing, i.e. deactivating, the brake F, reciprocally translating the clamping element or member 19 with respect to the support 15 and again activating the brake 19B when the desired position has been reached. After this adjustment has been performed along the first direction of adjustment substantially parallel to the numerically controlled axis X, adjustment of one or other or both of the vertical elements 151, 153 is performed, in the manner described above, using the numerically controlled movement of the head 9 along the vertical axis of translation Z. Adjustment in vertical direction (Z) takes place with the aid of a stop 10 again integral with the spindle casing or element 9A, or with the slide 7 (stop 10A indicated with a dashed line in Figure 6).

Figure 8 shows, in a side view, a modified embodiment of the machining centre in Figures 4 and 5. The same numbers indicate the same or equivalent parts to those in Figures 4 and 5. In this case the support 115 supports two series of clamping elements 19 opposed and mounted on an element or support 15X rotating or oscillating about a horizontal axis F, substantially parallel to the axis X and supported by the support 115. The letter f indicates the oscillating movement through 180° which can switch the reciprocal position of the two series of clamping elements or members 19 mounted in an axially symmetrical manner about the horizontal axis F.

To adjust the position of each clamping member 19 with respect to the support or element 15X and to the support 115 it is possible to rotate the element 15X about the axis F to a position rotated through +/- 90° with respect to the position shown in Figure 8 to place one or other of the groups of clamping members 19 in the same position as the clamping members 19 in Figure 4 with respect to the upright 103 and to the temporary constraining element 23, i.e. with the seat 25 oriented towards the latter. In this position it is possible to perform adjustment of the respective clamping members 19 along the axis X with the procedure described above. Alternatively, it would also be possible to place the seat 25 on the element 151 , thereby performing this first adjustment with the clamping members 19 in the horizontal position, i.e. in the angular position shown with a solid line in Figure 8.

Adjustment of the elements 151 and/or 153 of one or other of the two series of clamping members 19 mounted in axial-symmetrical position on the support 15 along the axis X takes place with the same methods as those described above by using the head 9 which is provided for this purpose with a stop 10 making use of the movement along the axis Y instead of along the axis Z. However, adjustment does not take place according to a vertical axis but preferably according to a horizontal axis Y, arranging the clamping members 19 in the position indicated with a solid line in Figure 8 or in the position rotated through 180° with respect to the one shown, according to which group of members 19 is to be adjusted.

Alternatively, adjustment of the elements 151 , 153 can take place arranging the clamping members 19 rotated through +/-90° in the position indicated with a dashed line in Figure 8, and using a stop in position 10A on the head 9 or on the spindle casing 9A, which will be rotated for this purpose through 90° about the axis A of rotation. Alternatively, a stop carried by the slide 7 and indicated with 10' can be used. If adjustment of the elements 151 , 153 takes place with the support in the position shown with a solid line in Figure 8, instead of the stop 10 carried by the spindle casing 9A, there can be used a stop 10'" integral with the upright 103, or a stop 10" integral with a fixed structure 104, which could be part of a loader positioned at the opposite end of the base 10 with respect to the upright 103.

As in the previously described examples, also in this case adjustment of the clamping members 19 along the horizontal guides 117 parallel to the axis X is performed first, so that the control unit of the machining centre 1 knows the position of the clamping members 19 along this axis or more specifically the position of the support 15 and the position of the clamping members 19 with respect to the support 15. After performing this first adjustment, the second adjustment orthogonal to the axis X is performed by making one and/or the other of the elements 151, 153 of each clamping member interact with the stop 10 or with the stop 10A of the head 9.

Figures 9, 10 and 11 show a machining centre 1 substantially the same as the one in Figures 1 to 3 (in Figures 9 to 11 the tool head and relative elements that allow movement thereof have been omitted to simplify representation). The same numbers are used to indicate the same or equivalent parts to those in Figures 1 to 3. The machining centre 1 in Figures 9 to 11 differs from the one in Figures 1 to 3 due to the absence of adjustment along the second direction of vertical adjustment (parallel to the axis Z) of the clamping members 19. In fact, in this case each of the clamping members or elements 19 is adjusted only according to a direction of adjustment substantially parallel to the numerically controlled axis X.

All the configurations shown are provided with a stop 100 against which the single clamping members 19 can be carried at the beginning of a positioning cycle. The stop 100 identifies a zero position with respect to which the members 19 are then translated and positioned. It is understood that the drawing only shows an example provided by way of a practical arrangement of the invention, which can vary in forms and arrangements without however departing from the scope of the concept underlying the invention. Any reference numbers in the appended claims are provided to facilitate reading of the claims with reference to the description and to the drawing, and do not limit the scope of protection represented by the claims.

Claims

1. A machining centre or machine tool, comprising a tool head and at least one support for workpieces to be machined, movable with respect to each other along a plurality of numerically controlled axes of translation, wherein:

- said at least one support is movable along at least a first numerically controlled axis;

- said at least one support is provided with a plurality of clamping members adjustable in variable positions along at least one direction of adjustment, substantially parallel to one of said numerically controlled axes of translation, stop devices being provided to fasten said clamping members in the desired position along said direction of adjustment;

- a temporary constraining element associated with a load bearing structure is provided to temporarily constrain said clamping members to said structure, said clamping members being designed to be temporarily constrained to said constraining element;

- said structure and said at least one support being reciprocally movable with a numerically controlled movement to adjust said clamping members along said direction of adjustment. 2. Machining centre as claimed in claim 1 , wherein said numerically controlled reciprocal movement to adjust the clamping members is controlled by one of the numerically controlled axes provided on the machining centre for machining workpieces.

3. Machining centre as claimed in claim 1 or 2, wherein said head is movable along at least a second numerically controlled axis.

4. Machining centre as claimed in claim 1 , 2 or 3, wherein said direction of adjustment is a substantially horizontal direction.

5. Machining centre as claimed in claim 1 , 2 or 3, wherein said direction of adjustment is substantially parallel to a numerically controlled axis of translation of the head.

6. Machining centre as claimed in one or more of the previous claims, wherein said direction of adjustment is substantially parallel to a numerically controlled axis of translation of said support.

7. Machining centre as claimed in one or more of the previous claims, wherein said head is provided with a movement according to at least one numerically controlled axis with respect to said temporary constraining element.

8. Machining centre as claimed in claim 7, wherein said head is provided with a numerically controlled translational movement with respect to the structure carrying the temporary constraining element.

9. Machining centre as claimed in one or more of the previous claims, wherein said support is movable along said first numerically controlled axis, to move reciprocally towards and away from said clamping members and said temporary constraining element.

10. Machining centre as claimed in claim 9, wherein said structure with which the temporary constraining element is associated is an upright, on which said head is supported and wherein said at least one support and said upright are provided with a reciprocal movement towards and away from each other .

11. Machining centre as claimed in claim 10, wherein said reciprocal movement towards and away from each other is a numerically controlled movement along a numerically controlled axis.

12. Machining centre as claimed in claim 10 or 11 , wherein said head is provided with at least one translational movement according to a numerically controlled axis along said upright.

13. Machining centre as claimed in claim 10, 11 or 12, wherein said upright is carried by a fixed base and said support is provided with a first movement towards and away from said upright and with a second translational movement substantially parallel to said direction of adjustment.

14. Machining centre as claimed in claim 13, wherein said first and said second movement are numerically controlled movements along numerically controlled axes.

15. Machining centre as claimed in one or more of claims 10 to 12, wherein said upright is movable along a numerically controlled axis of translation and wherein said direction of adjustment is substantially parallel to said axis of translation along which the upright is movable.

16. Machining centre as claimed in one or more of the previous claims, wherein said support is movable along a first guide substantially parallel to said first numerically controlled axis and to said direction of adjustment, and wherein a second guide substantially parallel to said first guide and along which said clamping members are adjustable is constrained to said support. 17. Machining centre as claimed in claim 16, wherein said first guide is carried by the structure with which said temporary constraining element is associated.

18. Machining centre as claimed in claim 16, wherein said structure with which said temporary constraining element is associated is integral with a base with which said first guide is integral.

19. Machining centre as claimed in claim 16, wherein said first guide is provided on a carriage movable along a third guide not parallel to the first and to the second guide, to allow the clamping members to move towards and away from the load bearing structure with which said temporary constraining element is associated.

20. Machining centre as claimed in claim 19, wherein said third guide and said first guide are oriented at approximately 90° with respect to each other and parallel to two numerically controlled axes of translation.

21. Machining centre as claimed in claim 19 or 20, wherein said third guide is disposed on a base associated with an upright on which said head is arranged, the upright carrying said temporary constraining element and the clamping members being selectively moved towards the temporary constraining element by means of a movement of said carriage along said third guide and being adjusted along the direction of adjustment by means of a movement of the support along said first guide, the movements along the first and the third guide being numerically controlled movements.

22. Machining centre as claimed in one or more of the previous claims, comprising a gantry on which said head is mounted.

23. Machining centre as claimed in claim 22, wherein under said gantry there extends a fixed structure carrying said temporary constraining element and with which a sliding guide of said at least one support is associated, the movement of the support along said guide being a numerically controlled movement; and wherein said support is provided with an adjustment guide substantially parallel to said sliding guide and on which said clamping members are adjustable.

24. Machining centre as claimed in one or more of the previous claims, comprising a control unit of the movements along the numerically controlled axes, programmed to store the positions of said clamping members and to perform adjustment and/or positioning of the clamping members on the basis of memorized information relative to the position of said clamping members.Machining centre as claimed in one or more of the previous claims, wherein said clamping members are adjustable in a second direction of adjustment, not parallel to the first direction of adjustment. 26. Machining centre as claimed in claim 25, wherein said second direction of adjustment is substantially orthogonal to the first direction of adjustment.

27. Machining centre as claimed in claim 25 or 26, wherein said second direction of adjustment is substantially vertical. 28. Machining centre as claimed in claim 25, 26 or 27, wherein a control unit of the movements along the numerically controlled axes is programmed to perform positioning or adjustment of the clamping members sequentially first along one of the directions of adjustment and subsequently along the other of the directions of adjustment. 29. Machining centre as claimed in one or more of claims 25 to 28, wherein adjustment along said second direction of adjustment is performed by means of interaction between the head and the clamping elements, the final position of the clamping members being defined by means of the numerically controlled position of the head along a numerically controlled axis substantially parallel to the second direction of adjustment.

30. Machining centre as claimed in one or more of claims 25 to 29, wherein said head is provided with a movement along at least two numerically controlled axes of translation not parallel with each other, and wherein adjustment of the clamping members along said second direction of adjustment takes place subsequent to adjustment along said first direction of adjustment, for each clamping member to be adjusted the head being positioned along one of said at least two numerically controlled axes of translation to carry a stop integral therewith to the level of the respective clamping member, and the relative clamping member subsequently being made to interact with said stop, the final position of said clamping member being determined by the position of said head along the other of said at least two axes of translation.