[0002] In addition, the present invention relates to a workholding fixture unit, a fixture table and a corresponding machine for the manufacture of elongated workpieces.

[0003] As is known, the machine tools for elongated workpieces use workholding fixture devices in order to grip the workpiece on suitable tables during machining carried out by special toolholding heads.

[0004] The prior art workholding fixture devices do not easily allow for the execution of simultaneous machining operations on several workpieces, consequently the relevant machine tools are slow and somewhat unproductive. Indeed, the known workholding fixture devices require a large amount of space between two adjacent workpieces in order to allow the toolholding head to perform the machining operations simultaneously.

[0005] Furthermore, the known workholding fixture devices frequently cause encumbrance problems with the toolholding heads whereby they do not allow the execution of all the machinings with a single locking of the workpiece, and require the interruption of the

machining and the repositioning of the workpiece, with further prolonging of the production times for the finished workpiece.

[0006] Furthermore, the prior art workholding fixture devices, after having carried out the locking of the workpiece, do not allow the machining of the side and end surfaces of the workpiece along its entire length, thereby requiring additional repositionings.

[0007] The problem of the present invention is that of providing a workholding fixture device which solves the drawbacks mentioned with reference to the known art.

[0008] Such drawbacks and limitations are solved by a workholding fixture device in accordance with claim 1.

[0009] Other embodiments of the workholding fixture device according to the invention are described in the subsequent claims.

[0010] Further characteristics and advantages of the present invention will be mostly understood from the following description of the preferred and non-limiting example embodiments thereof, wherein: [0011] Figure 1 represents a perspective view of a workholding fixture device according to the present invention; [0012] Figure 2 represents a side view, partially in section, of the workholding fixture device of figure 1,

from the side of arrow II of figure 1 ; [0013] Figure 3 represents a perspective view of the workholding fixture device of figure 1, mounted on related supporting means; [0014] Figure 4 represents an additional perspective view of the workholding fixture device of figure 1, mounted on related supporting means, according to an additional embodiment; [0015] Figure 5 represents a perspective view of a bracket unit comprising workholding fixture devices of figure 1 ; [0016] Figure 6 represents an additional perspective view of a bracket unit comprising workholding fixture devices of figure 1 ; [0017] Figure 7 represents a perspective view of a machine tool for the machining of elongated workpieces comprising the workholding fixture device of figure 1 ; C00l83Figure 8 represents a schematic front view of a machine tool for the machining of elongated workpieces comprising workholding fixture devices according to the invention; [0019] Figure 9 represents a perspective view of a workpiece table.

[0020] The components or component parts in common between the embodiments described in the following will

be indicated with the same numerical references.

[0021] With reference to the aforementioned figures, with 4 has been generally indicated a workholding fixture device, in particular for an elongated workpiece P having a prevailing extension E, surrounded by at least one side surface, said workholding fixture device 4 being adapted to being mounted on a machine tool 6 for the machining of elongated workpieces P. Said workpiece P extends along the prevailing extension E between two opposite ends P', P''.

[0022] With the term workpiece P having a prevailing extension E is meant an elongated workpiece P, for example a rod having any cross section or shape with respect to a cross sectional plane perpendicular to said prevailing extension E. Said workpiece P may be intended for the manufacture of finished products having an elongated shape, such as for example chair or table legs, made for example in wood or plastic material. Said workpieces P along the prevailing extension E are surrounded by at least one side surface. For example said side surface may be the cylindrical side surface of a circular, elliptical, square or polygonal cross section cylinder, typically used in the manufacture of chair or table legs.

[0023] According to one embodiment, the workholding

fixture device 4 comprises a body 10 adapted to interacting with gripping means 16 in order to constrain the workpiece P to the workholding fixture device 4.

[0024] The body 10 comprises a base 22 adapted to interacting with supporting means 28 of the workholding fixture device 4.

[0025] By base is meant both the physical surface of the body of the workholding fixture device 4, and a theoretical plane parallel to a plane constituted by the X and Y axes perpendicular to one another together, which are the axes of movement of the tools in the working plane of a machine.

[0026] The base 22 is for example planar in such a manner that, in one preferred assembly configuration of the workholding fixture device 4 on a relevant machine tool 6, said base 22 is substantially parallel to a support plane S of the machine itself, parallel to a pair of said axes X, Y perpendicular to one another.

[0027] Preferably the body 10 has a prevailing dimension C so that, with respect to a direction perpendicular to said prevailing dimension C a thickness G of the body itself may be defined.

[0028] The body 10 comprises a reference surface A adapted to supporting said gripping means 16 for the workpieces P.

[0029] The reference surface A preferably comprises a curved surface having at least one line of reference 1 for the workpiece P; preferably said reference surface A is a convex surface on the part facing towards the workpiece P to be held. Said curved surface is for example a part of the side surface of a cylinder wherein the generatrices are all substantially parallel to one another. Each of said generatrices constitutes a line of reference 1 for the workpiece P, that is it may constitute a theoretical line of contact between the side surface of the workpiece P and the reference surface A.

[0030] Said at least one line of reference 1 for the workpiece P forms an, advantageously acute, angle a with the base 22, that is, less than 90 sexagesimal degrees.

[0031] Advantageously, said angle a is comprised of between 10 and 60 sexagesimal degrees, preferably, it is equal to 35 sexagesimal degrees.

[0032] According to one embodiment, said gripping means 16 comprise a pair of jaws 34,36 adapted to locking the workpiece P to be machined.

[0033] In particular, said pair of jaws 34,36 comprises at least one movable jaw 34, i. e. sliding substantially parallel to said reference surface A.

[0034] According to one additional embodiment, said

moveable jaw 34, is moveable according to a direction, incident with said reference surface A.

[0035] For example, as is represented in figure 3, the moveable jaw 34 is moveable according to a direction substantially perpendicular to said reference surface A.

[0036] According to one embodiment, said moveable jaw 34 comprises a housing 40 adapted to, at least partially, house a moveable body 46.

[0037] Preferably, said housing 40 is fixed to the body 10 of the workholding fixture device 4 through slotted holes 47 and relevant threaded means of connection, in such a manner as to be able to vary its position of fixing along the reference surface A.

[0038] Said moveable body 46 comprises for example a stem 48 operated by relevant means of actuation, not represented, such as for example pneumatic, hydraulic, electric motor, recirculating ball screw mechanism actuations and the like.

[0039] Said stem 48 is movable according to a translation motion substantially parallel to the reference surface A.

[0040] Preferably, the stem 48 translates along a direction of advancement L which forms an angle of advancement y with said line of reference 1 of the reference surface A.

[0041] According to one direction of advancement towards the reference surface A, said angle of advancement y is advantageously comprised of between 0 and 5 sexagesimal degrees, preferably it is equal to 0.5 sexagesimal degrees.

[0042] The stem 48, at one end which faces towards the workpiece P for gripping, has a first striking surface Q adapted to pulling up against the workpiece P. According to one embodiment, said first striking surface Q is a canopy surface.

[0043] The jaw 36, opposite the moveable jaw 34 along the reference surface A, is preferably fixed with respect to the reference surface A and is positioned at one end of the reference surface A facing towards the part opposite said base 22.

[0044] The jaw 36 comprises a second striking surface R substantially perpendicular to the reference surface A.

[0045] Preferably, the second striking surface R has a curved surface, convex on the part facing towards the workpiece P to be held, for example a portion of a side surface of a cylinder in which the striking generatrices or lines M are all substantially parallel to one another and preferably perpendicular to the line of reference 1 constituting the reference surface A.

[0046] Advantageously, the second striking surface R, on

the side of the opposite moveable jaw 34, forms with a perpendicular to the reference surface A, a locking angle p comprised of between 0 and 10 sexagesimal degrees, preferably equal to 1 sexagesimal degree.

[0047] Said locking angle p is obtained for example through the machining, following the assembly of the jaw 36 substantially perpendicularly to the reference surface A.

[0048] Advantageously, the jaw 36 is connected to the reference surface A in such a manner as to specify a common reference edge 64 therewith.

[0049] In other words, said reference edge 64 is constituted by the intersection between the generatrices or lines of reference 1 of the cylindrical surface of the plane of locking A and the generatrices or striking lines M of the second striking surface R.

[0050] Said reference edge 64 may be curvilinear, i. e. comprising an arch, and is constituted by the locus of the reference points usable by a control system of a machine tool for the resetting of the position of the workpiece P.

[0051] According to one embodiment, illustrated for example in figure 1, said body 10 comprises reference means 65 adapted to forming an axial reference for the workpiece P, preferably according to a direction

parallel to the prevailing extension E. For example said reference means 65 may comprise a rod 66 rotating around an axis of rotation substantially parallel to said direction of prevailing extension E; said rod, rotating for example from a resting position of the rod 66, wherein for example it is arranged parallelly to said base 22, in such a manner as to not interfere with one of the ends P', P''of the workpiece P, to a working position of the rod 66, wherein said bar 66 is rotated in such a manner as to move up against one of said ends P', P''of the workpiece P. The point or area of contact between said rod 66 and said end P'or P''of the workpiece P advantageously constitutes a reference for the positioning of the workpiece P on the workholding fixture device 4 along a direction which is substantially parallel to said prevailing extension E.

[0052] In general, the gripping means 16 define a gripping point 68 adapted to holding at least one part of the workpiece P to be locked.

[0053] According to one advantageous embodiment, shown for example in figure 3, the workholding fixture device 4 comprises at least two bodies 10 placed side by side to one another along the prevailing dimension C of the bodies themselves.

[0054] Said bodies 10, preferably placed side by side

along a common prevailing direction C, forming a multiple workholding fixture device having a single crossbeam 70 from which several reference surfaces A originate, preferably parallel to one another, or having corresponding reference angles a differing from one another. The gripping means 16 define a plurality of gripping points 68 for similar workpieces P being locked and machined. According to one additional embodiment, said bodies 10 are arranged side by side along different prevailing directions C parallel with one another. In other words, said bodies are parallel with one another but staggered for example by a distance equal to the thickness G of the bodies themselves.

[0055] Preferably, with the multiple workholding fixture devices, the reference surfaces A are arranged side by side. and parallel to one another; in other words the reference surfaces comprise at least one line of reference 1 which has the same distance from said base 22. Advantageously, the gripping means 16 work according to a direction parallel to the line of reference of the reference surfaces, in such a manner that generally, the reference surfaces and the gripping means are arranged in parallel, side by side and at least partially overlapping one another. In other words, the reference surfaces A and the gripping means 16 are inclined in

such a manner that at least one of the gripping means 16 of one body 10 of one workholding fixture device 4, for example a fixed jaw 36, overlaps the gripping seat 68 of the adjacent body 10 with respect to a direction perpendicular to said reference surface A.

[0056] According to one advantageous embodiment, shown for example in figures 5 and 6, two workholding fixture devices 4 are arranged side by side and aligned with one another with respect to a direction perpendicular to the corresponding prevailing direction C, in such a manner as to form a bracket unit 76.

[0057] On the bracket unit 76 the workpiece P may be mounted protruding between the two workholding fixture devices 4, for example with the opposing ends P', P'', housed within the corresponding gripping seats 68 of the workholding fixture devices themselves; said ends P', P''being opposing with respect to said prevailing extension E.

[0058] Preferably, the clamping unit 76 comprises multiple workholding fixture devices 4, each comprising a plurality of gripping seats 68 for similar workpieces P to be gripped.

[0059] In this manner, on one clamping unit comprising multiple workholding fixture devices, a plurality of workpieces P, parallel to one another may be mounted.

[0060] Furthermore, on one bracket unit comprising multiple workholding fixture devices a plurality of workpieces P may be mounted in such a manner that all the workpieces have the same distance from the base 22.

10061] The workholding fixture device 4 is mounted on supporting means 28 which are preferably drivable. In particular, the workholding fixture device is drivable along the axes of translation and/or rotation X, Y, Z in such a manner as to be able to adapt the clamping unit 76 to workpieces of different dimensions.

[0062] For example, said supporting means 28 are drivable along said axes of translation and/or rotation X, Y, Z through pneumatic, hydraulic, electrical, manual types of actuation and the like.

[0063] For example the driving of the supporting means 28 around the axes of rotation X, Y, Z may come about using tables rotating or tilting within the respective reference planes.

[0064] According to one embodiment, the supporting means 28 rest on a workpiece table 90 adapted to moving in a plane parallel with said base 22 and with said plane of support S of the machine tool 6.

[0065] Said workpiece table 90 is preferably adapted to rotating around an axis parallel with said axis Z or to rotate or tilt with respect to the axis parallel to the

axes X, Y in order to allow the orientation of the workholding fixture device and/or the clamping unit 76 on planes suitable for facilitating the machining of the workpiece P.

[0066] Advantageously, the workholding fixture device 4, the clamping unit 76 and the workpiece table 90 are adapted to being mounted on said machine tool 6 for the working of elongated workpieces P.

[0067] According to one embodiment, said machine tool 6 comprises a frame 94 having for example two struts 96, extending in a direction parallel to the axis Z, and a central crossbeam 98 extending in a direction parallel to said plane X, Y.

[0068] The frame 94 defines a worlcspace 102 adapted to receiving the workpiece to be machined.

[0069] Preferably, on the central crossbeam 98 is mounted a tool holder unit 106, adapted to running along said central crossbeam 98 and parallelly therewith on appropriate guides 110.

[0070] Said tool holder unit 106 comprises a plurality of toolholding heads 114 for the machining of the workpiece P.

[0071] Advantageously the toolholding heads 114 provide at least three axes of translation X, Y, Z which define three axes of positioning and/or working perpendicular

to one another. Preferably, each of said axes is controlled in nature; as well as operatively connected to an actuation and control unit. Preferably, the controlled actuation is of the retroactivated control type.

[0072] Preferably, the toolholding heads 114 are mounted on the toolholding head unit 106 in such a manner as to rotate around an axis of rotation for example parallel to said axis Z, in such a manner as to define a fourth controlled axis of positioning and/or working IV operatively connected to an actuation and control unit.

[0073] Preferably, the toolholding heads 114 are mounted on the toolholding head group 106 in such a manner as to be able to rotate around an axis of rotation for example parallel to said axis Y, in such a manner as to define a fifth controlled axis of positioning and/or working V operatively connected to an actuation and control unit.

[0074] Substantially below said frame 94, is positioned a bed 118, arranged for example perpendicularly to said central crossbeam 98 and adapted to movably supporting at least one workpiece table 90, allowing said at least one workpiece table 90 to translate for example in a direction perpendicular to said central crossbeam 98.

[0075] The operation of the workholding fixture device according to the invention will now be described.

[0076] At least one workpiece P is previously positioned on a bracket unit 76 for example oriented in such a manner as to have its prevailing extension E substantially perpendicular to the prevailing dimensions C of the bodies 10 of the workholding fixture devices 4.

[0077] In particular, the opposite ends of the workpiece P with respect to its prevailing extension E are positioned in correspondence with the gripping seats 68 of the workholding fixture devices, facing towards one another according to a direction perpendicular to the prevailing dimension C of the corresponding workholding fixture devices 4.

[0078] The workpiece P is positioned in close proximity to the gripping seats 68, in such a manner as to make at least one part of its side surface rest against at least one of the second striking surfaces R of the jaw 36 and the reference surface A of the body.

[0079] In particular, according to requirements, due for example to the peculiar dimensions of the workpiece P, the two workholding fixture devices may move with respect to the axes of translation and/or rotation X, Y and Z in such a manner for example so as to select the preferred distance between the locking surfaces A of the workholding fixture devices 4.

[0080] Therefore, in order to ensure the locking of the

workpiece the moveable jaws 34 are actuated in such a manner as to grasp each end P', P''of the workpiece P between the pairs of jaws 34,36.

[0081] Following the locking operation, the side surface of the workpiece P is placed in contact with at least one line of reference 1 of the reference surface A and/or with at least one striking line M of the second striking surface R.

10082] The presence of the locking angle p and the angle of advancement y helps the locking and the wedging of the workpiece towards the reference edge 64.

[0083] After having fastened the workpiece P to the workholding fixture device 4, the workpiece and the toolholding heads 114 are brought side by side, for example by making the workpiece table 90 on which the bracket unit is mounted 76 translate towards the central crossbeam 98 of the frame 94.

[0084] Preferably, the toolholding heads 114 take the reference edge 64, formed by the intersection of the striking line M with the line of reference 1 as a resetting point.

[0085] In the multiple workholding fixture devices, the reference edges may be parallel to one another in such a manner as to allow the precise and repeatable resetting operation of the toolholding head in the changeover from

the machining of one workpiece to another.

[0086] The machining operations may occur over the entire prevailing extension E of the workpiece P, comprising said ends P'and P''.

[0087] As may be appreciated from what described, the described workholding fixture device allows the overcoming of the drawbacks shown by the workholding fixture devices of the known art.

[0088] In particular, the angled layout of the workpiece on the relevant workholding fixture devices allows having the maximum number of workable workpieces with parity of length to that of the workpiece table and of the course of the axes of the machine.

[0089] It is therefore possible to arrange and lock many workpieces simultaneously, by optimising the space available on the workpiece table.

[0090] Furthermore, the angled layout of the workpiece on the workholding fixture devices allows for the working of the workpiece over its entire prevailing extension including the opposite ends, hence performing a single positioning and gripping of the workpiece on the workholding fixture device. For example, for a square cross-sectioned, cylindrical workpiece, adapted to manufacturing chair or table legs, the described workholding fixture device allows the working of all the

faces of the side surfaces of the workpiece along the extension E, thanks to the angled layout of the workpiece P, preferably with the aid of a machine tool having for example three working axes.

[0091] Furthermore, the workholding fixture device according to the invention allows performing simultaneous machinings on several workpieces without having the problems of interference between the toolholding heads and the positioned workpieces.

[0092] Furthermore, with a single positioning of the workpiece, it is possible to have access to all the faces of the side surface of the workpiece, thus achieving more rapid and more precise machining. Indeed such workings do not require the disassembly of the workpiece, its new positioning, the subsequent reassembly and the resetting of the position of the toolholding head.

[0093] An additional advantage lies in the fact that the grouped layout of the workpieces on the workholding fixture device allows, following machining with the tool, of having finished or semi-finished products that are easily releasable from the machine using automated, for example by rack, or manually driven systems.

[0094] One skilled in the art, with the aim of satisfying contingent and specific needs, may bring about a number

of modifications and variations to the above described workholding fixture devices, which are all contemplated within the scope of the invention as defined by the following claims.