WO2025215544A1

WO2025215544A1 - Numerically controlled machine tool with double machining

Info

Publication number: WO2025215544A1
Application number: PCT/IB2025/053717
Authority: WO
Inventors: Giuseppe BACCI; Paolo BACCI; Nino BACCI
Original assignee: Paolino Bacci SRL
Current assignee: Paolino Bacci SRL
Priority date: 2024-04-10
Filing date: 2025-04-09
Publication date: 2025-10-16
Anticipated expiration: 2026-10-10

Abstract

A machine tool for machining wooden workpieces comprising: - a support unit for a plurality of workpieces to be machined, comprising a plural- ity of rotation devices for respective workpieces to be machined, each rotation device defining a first motorized rotation axis, around which the workpiece to be machined is adapted to rotate during machining, said devices being arranged with the respective said first axes parallel and mutually staggered in a direction from bottom to top, - a first machining module of the workpieces present in said support unit compris- ing a plurality of first machining heads carrying first machining tools, configured to interact with the workpieces provided in said rotation devices, said first mod- ule being arranged facing a first side of said support unit, - a second machining module of the workpieces present in said support unit com- prising a plurality of second machining heads carrying second machining tools, configured to interact with the workpieces provided in said rotation devices, said second module being arranged also facing said first side of said support unit, so that first and second module interact with the workpieces to be machined from the same side of the support unit, and wherein respective first and second ma- chining head are configured to act on the same workpieces provided in respec- tive rotation devices.

Description

NUMERICALLY CONTROLLED MACHINE TOOL WITH DOUBLE MACHINING

Description

Technical field

[0001] The present invention concerns the field of numerically controlled machine tools. More specifically, the subject of the invention is a machine that allows double machining on the same workpieces.

[0002] The invention applies for example to numerically controlled lathes, for example also of multi-spindle type and numerically controlled lathe turning centers.

State of the art

[0003] Numerically controlled multi-spindle lathes are known that comprise a plurality of pairs of numerically controlled motorized members for rotating workpieces to be machined. Each pair comprises a headstock and a tailstock coaxial to each other and defining a respective rotation axis of the workpieces to be machined. These pairs of members are associated with a movable station carrying a plurality of spindles with milling tools, one for each pair of members. The configuration is such as to perform identical machining operations on identical workpieces carried on the headstock and tailstock pairs. For said purpose, the headstock and tailstock pairs rotate in a synchronous manner. An example of said lathes is described in the Italian patent no. 102020000001789.

[0004] The workpieces machined with said lathes then have to be finished in further workstations such as, for example, further finishing lathes and sanding machines.

[0005] The sanding machines are also provided with motorized members for rotation of the workpieces to be machined, with each pair comprising a headstock and a tail- stock coaxial to each other and defining a respective rotation axis of the workpieces to be machined. For each pair there is a movable station provided with longitudinal sanding members that use “longitudinal” abrasive belts that operate in the direction of the axis of the workpiece to be sanded (which roughly corresponds to the direction of the wood fiber). Said belts are tensioned between guide rollers, of which one, generally motorized, acts as a contact roller between the belt and the surface to be sanded. An example of said systems is described in the Italian patent no. 101990900098214.

[0006] The main object of the present invention is to increase the flexibility and throughput of machine tools designed to perform different successive machining operations.

[0007] This and other objects, which will become clearer below, are achieved by a machine tool for machining wooden workpieces comprising: a support unit for a plurality of workpieces to be machined, comprising a plurality of rotation devices for respective workpieces to be machined, each rotation device defining a first motorized rotation axis, around which the workpiece to be machined is adapted to rotate during the machining, said devices being arranged with the respective said first axes parallel and mutually staggered in a direction from bottom to top, a first machining module of the workpieces present in said support unit comprising a plurality of first machining heads carrying first machining tools, configured to interact with the workpieces provided in said rotation devices, said first module being arranged facing a first side of said support unit, a second machining module of the workpieces present in said support unit comprising a plurality of second machining heads carrying second machining tools, configured to interact with the workpieces provided in said rotation devices, said second module also being arranged facing said first side of said support unit, so that first and second module interact with the workpieces to be machined from the same side of the support unit, and wherein respective first and second machining heads are configured to operate on the same workpieces provided in respective rotation devices.

[0008] Other aspects of the invention are described in the attached claims. of the

[0009] The invention will be better understood by following the description and the attached drawings, which illustrate some non-limiting embodiments of the invention by way of example. More specifically, in the drawing:

Fig. 1 shows a schematic view from above of a machine with sanding module according to the invention, together with a chip removal machining module;

Fig. 2 shows a lateral schematic view of the machine tool of figure 1 according to Illi of figure 3;

Fig. 3 shows a frontal schematic view of the machine tool of figure 1;

Fig. 4 shows a schematic view of the machine tool of figure 1 according to IV-IV of figure 1;

Fig. 5 shows a schematic view from above of a machine tool according to the invention, a variation with respect to figure 1 in relation to the second machining module;

Fig. 6 shows a lateral schematic view of the machine tool of figure 5, relative to the second machining module;

Fig. 7 shows a schematic view from above of a machine tool according to the invention, a variation with respect to figure 1 and figure 5, in relation to the second machining module;

Fig. 8 shows a lateral schematic view of the machine tool of figure 7, relative to the second machining module;

Fig. 9 shows a frontal schematic view of the machine tool of figure 7.

Detailed disclosure of embodiments

[0010] With reference to the preceding figures from 1 to 4, a machine tool according to the invention is indicated overall by the number 1. In this example, the machine tool is a multi-spindle lathe with two machining modules. [0011] In this example, the machine tool 1 comprises a supporting structure 3. The supporting structure 3 comprises a first vertical upright 5 and a second vertical upright 7, rigidly connected to a lower horizontal base 9. At the top, the uprights 5 and 7 are joined by a horizontal cross member 11.

[0012] The structure 3 is associated with a support unit 2 for a plurality of workpieces P. Said unit 2 in turn comprises a plurality of rotation devices 12 for respective workpieces P to be machined. Each rotation device 12 defines a first motorized rotation axis A, around which the workpiece to be machined is adapted to rotate during the machining operation. Each rotation device 12 also acts as a supporting member for the workpieces P to be machined.

[0013] More specifically, each rotation device 12 comprises a headstock 13 and a tailstock 15 coaxial to each other, which define the first rotation axis A of the workpiece to be sanded, wherein the headstock 13 is motorized (for example, each head- stock 13 is rotated around the respective axis A by means of a numerically controlled motor, not shown), and wherein the distance between the headstock 13 and the tail- stock 15 is adjustable, and wherein the first axis A preferably passes through said workpiece once it has been associated with the rotation device.

[0014] The rotation devices 12 for respective workpieces P to be machined are arranged mutually staggered, in this example in a vertical direction.

[0015] The first rotation axes A of the rotation devices 12 lie preferably on a vertical plane W. Expediently, in this example the machine tool 1 comprises two machine sides W 1 and W2 defined on opposite sides of the vertical plane W.

[0016] Advantageously, on the same machine side W1 two machining modules of the workpieces P are arranged, a first machining module 10 and a second machining module 100 respectively.

[0017] The first machining module 10 comprises a plurality of first machining heads 31 carrying first work tools Ul, configured to interact with the workpieces provided in the rotation devices 12. In this example a first head 31 is present for each rotation device 12. [0018] The second machining module 100 comprises a plurality of second machining heads 131 carrying first work tools U2, configured to interact with the workpieces provided in the rotation devices 12. In this example a second head 131 is present for each rotation device 12.

[0019] The upright 5 carries a plurality of said headstocks 13. The motors of the headstocks 13 are preferably controlled so that all the headstocks 13 perform synchronous rotations.

[0020] The tailstocks 15 are carried by a movable upright 17 with vertical extension. The movable upright 17 can be guided along upper adjustment guides carried by the cross member 11 and by lower adjustment guides 19, integral with the base 9 and extending in the development direction of the base 9. In this way it is possible to adapt the distance between all the headstocks 13 and the respective tailstocks 15 to the length of the workpieces P to be machined.

[0021] The base has two walls or lateral faces, a front face 9.1 and a rear face 9.2 (cf. Fig. 2).

[0022] The machine tool 1 comprises movement means for the first and second heads 31, 131 according to a direction toward and away from a respective first axis A to follow the profile of the workpiece in said direction and adjust the machining pass depth, and a direction parallel to a respective said first axis, to allow machining along the whole length of the workpiece.

[0023] In this regard, on the rear face 9.2 a first guide 21 is applied, which extends according to a first translation direction, namely a first horizontal translation axis indicated by the double arrow X, parallel to the first rotation axes A.

[0024] With regard to the above-mentioned movement means, the first guide 21, for example, engages with a first carriage or slide 23, which takes the form of a movable upright with respect to the base 9. The first carriage 23 is movable along the first guide 21 according to the first translation axis X, horizontal. The movement of the first carriage 23 along the axis X is a numerically controlled movement, for example driven by its own motorization. [0025] The first carriage 23 extends for example vertically beyond the maximum height of the base 9. The first carriage 23 carries a second carriage or slide 25, which is movable along a second translation axis indicated by the double arrow Yl, for examples thanks to its own motorization. The second translation axis Yl is horizontal and orthogonal to the first translation axis X. To allow the movement along the second translation axis Yl, the second carriage 25 is provided with a second guide 27, which engages in sliding blocks 29 integral with the first carriage 23.

[0026] The second carriage 25 carries the machining heads 31 with the first tools U 1. Said first heads are, for example, first spindles on which the tools U1 can be applied (below, the first spindles will also be numbered 31).

[0027] The number of first spindles 31 and the number of first tools U1 is equal to the number of rotation devices, namely the number of pairs of headstocks 13 and tailstocks 15.

[0028] The first spindles 31 can be rotated simultaneously by means of motors in number identical to or different from the number of first spindles 31. In the example illustrated, two motors 33 are provided, each of which controls the rotation of two spindles 31.

[0029] Thanks to the movements on the translation axes X and Y 1 described above, the first tools U1 can perform numerically controlled movements along the axis X to machine each point of the workpieces P held between the headstocks 13 and the tailstocks 15. The numerically controlled movement along the translation axis Yl allows the tools U1 to be moved closer to and away from the lateral surface to be machined of the workpieces P held between the headstocks 13 and the tailstocks 15.

[0030] Therefore the first tools U1 can synchronously and simultaneously machine all the workpieces P supported and rotated by the pairs of headstocks and tailstocks 13, 15.

[0031] The second machining module 100 is able to operate on the same side W1 of the first machining module 10, on the same workpieces.

[0032] Analogously to the preceding case of the first machining module 10, the machine tool 1 comprises movement means for the second heads 131 analogous to those for the first heads 31. Therefore, below, the same movement components linked to the second heads 131 will be numbered in the same way as the first heads 31, starting from the number 100.

[0033] Therefore a further first carriage or slide 123 is engaged on a guide, in this case coinciding with the first guide 21, and takes the form of an upright movable with respect to the base 9. The further first carriage 123 is movable along the first guide 21 according to the first translation axis X, horizontal. The movement of the further first carriage 23 along the axis X is a numerically controlled movement, for example driven by its own motorization.

[0034] The further first carriage 123 extends, for example, vertically beyond the maximum height of the base 9. The further first carriage 123 carries a further second carriage or slide 125, which is movable along a further second translation axis indicated by the double arrow Y2. The further second translation axis Y2 is horizontal and orthogonal to the first translation axis X. To allow the movement along the further second translation axis Y2, the further second carriage 125 is provided with a further second guide 127, which engages in further sliding blocks 129 integral with the further first carriage 123. The movement along the second translation axis Y2 is a numerically controlled movement, for example driven by its own motorization.

[0035] Analogously, the further second carriage 125 carries the second machining heads 131 with the second tools U2. Said heads are, for example, spindles on which the tools U2 can be applied (below, the spindles will also be numbered 131).

[0036] The number of second spindles 131 and the number of second tools U2 is equal to the number of rotation devices 12, namely the number of pairs of headstocks 13 and tailstocks 15.

[0037] The second spindles 131 can be rotated simultaneously by means of motors having number identical to or different from the number of second spindles 131. In the example illustrated, two motors 133 are provided, each of which controls the rotation of two second spindles 131.

[0038] Thanks to the movements on the translation axes X and Y2 described above, the second tools U2 can carry out numerically controlled movements along the axis X to machine each point of the workpieces P held between the headstocks 13 and the tailstocks 15. The numerically controlled movement along the translation axis Y2 allows the tools U2 to be moved toward and away from the lateral surface to be machined of the workpieces P held between the headstocks 13 and tailstocks 15.

[0039] The second tools U2 can synchronously and simultaneously machine all the workpieces P supported and rotated by the pairs of headstocks and tailstocks 13, 15. In this way it is possible, for example, to obtain identical machining on each workpiece, thus obtaining identical workpieces, if necessary.

[0040] In embodiments not shown in the figures, the second module can share with the first module a first carriage (25 or 125) sliding on the guides parallel to the axis X, on which the respective second carriages are mounted movable parallel to directions Y1 and Y2 respectively, carrying the respective heads with the tools U1 and U2. In practice the machining modules 10 and 100, namely the tools U1 and U2, will have the same feed speed along X. In this way, a single motorization can be used for the movement along X. In other embodiments not shown in the figures, the first carriage of the first module and the further first carriage of the second module are physically connected to each other, so that the first carriage 25, when moving along X, correspondingly drives the further first carriage 125 along the same axis. As a result, the machining modules 10 and 100, that is, tools U1 and U2, will have the same feed speed along the X-axis. In this way, a single motorization for the X-axis movement is possible; if needed, the first carriage and the additional first carriage may be disconnected to adjust their relative distance and then reconnected.

[0041] The machine tool 1 comprises an electronic control unit M configured to allow programmed numerically controlled movements of the machining heads 31, 131 on the workpieces P rotated by the rotation devices 12. For example, it can perform machining cycles on the workpieces P according to a given order, for example firstly all the cycles that can be carried out by the first heads 31 (obviously with the tools Ul) and then all the cycles that can be carried out by the second heads 131, or vice versa. The machine can also alternate, according to a set rate, cycles carried out by the first heads 31 and cycles carried out by the second heads 131. [0042] In some cycles, the first machining heads 31 and the second machining heads 131 can operate at least partly simultaneously on the same workpieces P rotated by the rotation devices 12.

[0043] Advantageously, the second carriage 25 and the further second carriage 125 are able to move the first and second machining heads 31 and 131 respectively very near to each other so that they operate in close proximity.

[0044] More specifically, the first and second machining heads 31 and 131 are arranged in the space between the first carriage 23 and the further first carriage 123, so that respective machining heads, namely the first and second tools U1 and U2, can be positioned side by side without the presence of the first carriage 23 and the further first carriage 123 between them, allowing simultaneous axially adjacent operations (namely adjacent in the direction X) on the workpiece P being machined. For example, to facilitate this conformation, the motors 33, 133 of the chip removal tools U1 and U2 of the machining heads 31, 131 extend cantilevered from the respective carriage in opposite directions to each other, as can be seen in figure 1 and 4. In practice, the first carriage 23 and the further first carriage 123 are crossed by two respective vertical planes orthogonal to the direction X. The machining heads 31, 131 associated with the first carriage 23 and the further first carriage 123 respectively (by means of the second carriage 25 and further second carriage 125), are positioned on the correspondingly facing sides of the two vertical planes, orthogonal to the direction X, that pass through the first carriage 23 and the further first carriage 123.

[0045] From another point of view, in practice, the minimum distance, measured in a direction parallel to the first axis A, obtainable between the first tool U1 and the second tool U2 configured to act on the same workpiece P provided on a respective rotation device 12, is configured to be smaller than the minimum dimension of the housing space of the workpieces P in the respective rotation device 12, again measured in a direction parallel to the first axis, so that both the first and the second tool U1 and U2 can operate throughout the length of the workpiece P being machined measured parallel to the first axis A. In this way the first and the second tool can operate simultaneously on the same workpiece. [0046] Furthermore, there is a first space SP1 (indicated in figure 1 and 4) outside the housing space of the workpiece P in the rotation device 12 and comprised between said housing space of the workpiece P and a first side of the machine, configured for positioning the first head 31, so that said first head 31 does not interfere with the work of the second head 131 close to the corresponding end of the workpiece. Analogously, on the opposite side of the rotation devices 12 with respect to the first space SP1, there is a second space SP2 outside the housing space of the workpiece P in the rotation device 12, comprised between said housing space of the workpiece P and a second side of the machine, configured for positioning the second head 31, so that said second head 31 does not interfere with the work of the first head 131 close to the corresponding end of the workpiece.

[0047] The two machining modules 10 and 100 can be two modules that perform shaping of the workpiece by chip removal. For example, the first machining module 10 can carry out roughing operations, while the second module can carry out more controlled chip removal operations.

[0048] In other cases the first module 10 can be a chip removal machining module that allows shaping of the workpiece, and the second machining module 100 can be a sanding module, which therefore does not carry out chip removal but operates by abrasion.

[0049] A chip removal machining module uses a chip removal tool which is provided with a cutting edge, for example defined, in a per se known manner, by a lower rake angle, formed by the front face of the cutting edge (main flank) and the machined surface of the workpiece; a cutting angle, formed by the upper face and the main flank; an upper rake angle, formed by the face of the tool over which the chip flows (upper face) with the plane passing through the cutting edge and perpendicular to the machined surface of the workpiece.

[0050] A sanding module uses a tool provided with one or more abrasion surfaces, the contact of which with the surface to be sanded does not comprise a cutting edge. The material is removed from the surface to be sanded by abrasion and not by the action of a cutting edge. [0051] In general, the first machining module can use first tools which are different from the second tools used. The difference can consist in the type or in the dimensions or cutting geometry.

[0052] The first tools can be, for example, milling cutters, of disc type, in this example with rotation axis parallel to the first rotation axes A of the devices 12.

[0053] For example, figures 1-4 show the case of a first machining module that uses first tools U1 which are disc cutters with rotation axis parallel to the first rotation axes A of the devices 12, while the second machining module comprises second tools U2 also in the form of a disc cutter with rotation axis parallel to the first rotation axes A of the devices 12. These two disc cutters U1 and U2 can be identical, so that the two modules 10 and 100 substantially perform the same chip removal operations (for example they can operate simultaneously on the workpiece to speed up the shaping operations). Alternatively said disc cutters U1 and U2 can be different, for example in terms of geometry or type of cutting edge, in order to carry out differentiated chip removal operations (for example roughing and finishing).

[0054] For example the milling cutters U1 are large dimension disc cutters, with diameter slightly smaller than the size of the center distance A-A between successive rotation devices.

[0055] If the tools U1 are milling cutters identical to the milling cutters U2, the former can be used for a roughing operation, for example, while the latter can be used for a finishing operation. In this case, the finishing pass of U2 is in general carried out with a feed per revolution slower than the one programmed (by numerical control) for the roughing pass performed with Ul. Roughing and finishing can be carried out in one single pass (for example with the tools operating at least to a certain extent simultaneously on the same piece), with considerable saving on time.

[0056] The two modules 10 and 100 (namely the tools Ul and U2) can therefore operate simultaneously on the same pieces with feed speeds along X that can be identical to or different from each other. [0057] Figures 5 and 6 show the case in which one of the two tools, for example the second tool U2, is not a large disc cutter but a different type of milling cutter tool, that also requires a movement from bottom to top or vice versa.

[0058] The machine tool I¹ shown in figures 5-6 has a structure for the most part identical to that of the lathe 1 of Fig. 1 to 4. Identical parts in the two embodiments are indicated by the same reference numbers and will not be described again.

[0059] The main difference, in the second machining module, now indicated by 100¹, between the embodiment of Fig.1 to 4 and the embodiment of Fig. 5-6 consists in the presence of a third carriage or slide 151, movable according to a third translation axis Z from bottom to top and vice versa, more preferably orthogonal to the first translation axis X and the second translation axis Yl, namely a vertical axis. More precisely, the third carriage 151 is interposed between the further first carriage 123 and the further second carriage 125. The further second carriage 125, instead of being engaged directly via its guides 127 on the further first carriage 123, is engaged with the guides 127 on the third carriage 151. The latter is in turn engaged via guides 153 with the further first carriage 123, to move with a numerical control along the third vertical translation axis Z. In this way the spindles 131 and the tools U2 can be moved according to three numerical control translation axes X, Yl, Z orthogonal to one another.

[0060] Furthermore, in the embodiment illustrated, the tools U2¹ and the spindles 131 have rotation axes parallel to the axis Yl and orthogonal to the axes X and Z and orthogonal to the rotation axes A of the headstocks 13 and tailstocks 15. The movement along Z allows the tools U2¹ to be positioned at variable heights with respect to the workpieces P to be machined.

[0061] It is clear that said movement solution of the heads/spindles 31/131 can be applied on any of the machining modules present in the machine tool, namely used for any type of tool used if it is necessary to give the heads/spindles also a vertical movement.

[0062] Figures 7-9 show the case of a machine lⁿ in which the second machining module, now indicated by 100¹¹, uses second tools U2ⁿ in the form of sanding devices. [0063] The structure of the module 100¹¹ with tools U2ⁿ is substantially analogous, for example, to that of figures 1-4 and comprises a further first carriage 123 engaged with the first guide 21 along X. The movement of the further first carriage 23 along the axis X is a numerically controlled movement.

[0064] The further first carriage 123 carries the further second carriage or slide 125, which is movable along Y2. The further second carriage 125 is provided with the further second guide 127, which engages in further sliding blocks 129 integral with the further first carriage 123.

[0065] The further second carriage 125 carries the second machining heads 131 which are supports for second tools U2ⁿ in the form of sanding devices. In particular the second tools U2ⁿ comprise pairs of rollers U21A-U21B, supported by respective supports 131 on the further second carriage 125. Said rollers U21 A-U21B, for example with axis orthogonal to the first axes A (in this example a vertical axis), are guide rollers for an abrasive belt U22 arranged in a closed loop on the rollers. One of the two rollers protrudes forward with respect to the carriage 125 to come into contact with the workpiece to be sanded. Said roller defines the contact arc of the abrasive belt with the workpiece to be sanded. The movement of the further second carriage 125 along Y2 toward the workpiece adjusts the abrasion pressure of the belt U22 (by means of the corresponding roller U21 A). In this example the sanding devices U2ⁿ are all supported directly on the further second carriage 125, so that they all move the same distance together. Activation of the guide rollers U21 is also preferably simultaneous for all the motorized rollers.

[0066] It is understood that the above description represents only possible non-limiting embodiments of the invention, which can vary in terms of form and arrangement without departing from the scope of the concept underlying the invention. The presence of any reference numbers in the attached claims has the sole purpose of facilitating the reading thereof in the light of the preceding description and the attached drawings and does not in any way limit the protective scope thereof.

Claims

1. Machine tool for machining wooden workpieces comprising a support unit for a plurality of workpieces to be machined, comprising a plurality of rotation devices for respective workpieces to be machined, each rotation device defining a first motorized rotation axis, around which the workpiece to be machined is adapted to rotate during machining, said devices being arranged with the respective said first axes parallel and mutually staggered in a direction from bottom to top, a first machining module of the workpieces present in said support unit comprising a plurality of first machining heads carrying first machining tools, configured to interact with the workpieces provided in said rotation devices, said first module being arranged facing a first side of said support unit, a second machining module of the workpieces present in said support unit comprising a plurality of second machining heads carrying second machining tools, configured to interact with the workpieces provided in said rotation devices, said second module being arranged also facing said first side of said support unit, so that first and second module interact with the workpieces to be machined from the same side of the support unit, and wherein respective first and second machining heads are configured to act on the same workpieces provided in respective rotation devices.

2. Machine tool according to claim 1, wherein at least one of the two groups formed by the first tools and by the second tools, respectively, is a group in which the tools are chip removal tools, preferably milling cutters; preferably said milling cutters are of disc type, preferably the rotation axes of said disc milling cutters are parallel to said first axes of said rotation devices; preferably the heads carrying said tools in the form of milling cutter are spindles.

3. Machine tool according to one or more of the preceding claims, wherein at least one of the two groups formed by the first tools and by the second tools, respectively, is a group in which the tools are sanding devices of the workpieces; preferably, each sanding device comprises a sanding belt, preferably arranged between two guide rollers.

4. Machine tool according to one or more of the preceding claims, wherein each rotation device comprises a headstock and a tailstock coaxial to each other and defining said first rotation axis of the workpiece to be machined, wherein said headstock is motorized, and wherein the distance between the headstock and the tailstock is adjustable, and wherein said first axis is preferably passing through the workpiece once associated with said rotation device; preferably, for each first and second machining module, each rotation device is provided with at least one respective said machining head; more preferably, each machining module is provided with a single machining head for each rotation device; preferably, the machining heads of each machining module are also staggered in a manner corresponding to said rotation devices; preferably, the centre distance between the machining heads corresponds to the centre distance between the headstocks and tailstocks of the rotation devices.

5. Machine tool according to one or more of the preceding claims, wherein the minimum distance, measured in a direction parallel to the first axis, obtainable between the first tool and the second tool configured to act on a same workpiece provided on a respective rotation device is configured to be less than the minimum dimension of the space for housing the workpieces in the respective rotation device measured in a direction parallel to the first axis, so that both the first and the second tool can act on the whole of the length of the workpiece being machined measured parallel to the first axis.

6. Machine tool according to one or more of the preceding claims, comprising movement means for said first and second heads according to a direction toward and away from a respective said first axis to follow the profile of the workpiece and adjust the machining pass depth, and a direction parallel to a respective said first axis, to allow machining along the whole of the length of the workpiece.

7. Machine tool according to one or more of the preceding claims, comprising, for each said rotation device, a first space outside the space for housing the workpiece in the rotation device and comprised between said space for housing the workpiece and a first side of the machine, configured for positioning of the first head, so that this first head does not interfere with the work of the second head close to the corresponding end of the workpiece; similarly, on the opposite part of the rotation devices with respect to said first space, a second space is provided outside the space for housing the workpiece in the rotation device, comprised between said space for housing the workpiece and a second side of the machine, configured for positioning of the second head, so that said second head does not interfere with the work of the first head close to the corresponding end of the workpiece.

8. Machine tool according to one or more of the preceding claims, wherein said first machining module comprises a first carriage guided on a first guide extending in a first direction of translation parallel to said first rotation axis, wherein the first carriage is provided with a numerically controlled movement at least along said first direction, and a second carriage, supported by the first carriage, movable with a numerically controlled movement with respect to the first carriage, by means of a second guide, at least in a second direction of translation, orthogonal to the first rotation axis, wherein said first machining heads are provided on said second carriage.

9. Machine tool according to one or more of the preceding claims, wherein said second machining module comprises a further first carriage guided on a further first guide extending in a further first direction of translation parallel to said first rotation axis, wherein the further first carriage is provided with a numerically controlled movement at least along said further first direction, and a further second carriage, supported by the further first carriage, movable with a numerically controlled movement with respect to the further first carriage, by means of a further second guide, at least in a further second direction of translation, orthogonal to the first rotation axis, wherein said second machining heads are provided on said further second carriage.

10. Machine tool according to claims 8 and 9, wherein said further first guide coincides with said first guide, so that said first carriage and said further first carriage are configured to move on the same guide.

11. Machine tool according to one or more of the preceding claims, comprising movement means from bottom to top and vice versa, for said first and/or second machining heads, to allow vertical passes on the workpieces being machined.

12. Machine tool according to one or more of the preceding claims, comprising an electronic control unit configured to allow programmed numerically controlled movements of said machining heads on said workpieces; preferably, said electronic control unit is configured to allow machining cycles in which said first machining heads and said second machining heads are adapted to act at least partly simultaneously on the same workpieces rotated by said rotation devices; preferably, said electronic control unit is configured to allow machining cycles on the workpieces carried out first by said first heads and subsequently by said second heads, or vice versa.

13. Machine tool according to one or more of the preceding claims, wherein said first tools are the same as said second tools, or said first tools are different from said second tools.