Apparatus and method for support and controlled advancement of a metal sheet in a bending machine for obtaining cylindrical or truncated cone structures

Abstract

An apparatus for the support and the controlled advancement of a sheet in a bending machine for forming a cylindrical or conical structure, in particular of a truncated cone structure, comprises a base structural frame adapted to be positioned upstream of said bending machine, with respect to an advancement direction of the sheet, a plurality of conveying modules which can be mounted, removable, on the structural frame so as to generate a plan of modular support and advancement which can be configured geometrically according to the shape and dimensions of the sheet to be produced; the modular support and advancement plane is geometrically configured to keep the sheet metal part supported by the plane in a flat condition; an lifting and tilting device configured to vary the position of the structural frame, supporting the conveying modules, from a horizontal lying position to an inclined lying position in which the support and advancement plane is inclined downwards towards the bending machine; repositioning and position correcting members configured to orient and arrange the sheet in a correct position before starting a bending cycle and configured to correct, during the bending cycle, the position of the sheet to impose it a predetermined advancement trajectory towards and through the bending machine. The relative method is also envisaged.

Claims

1. Apparatus for the support and controlled advancement of a metal sheet in a bending machine for forming a cylindrical or conical structure, in particular a truncated cone structure, said apparatus comprising: a base structural frame suitable for being positioned upstream of said bending machine, with respect to an advancement direction of the metal sheet, a plurality of conveying modules configured for being fitted, removably, to said structural frame so as to generate a modular support and advancement plane that is geometrically configurable in function of the shape and dimensions of the metal sheet to be processed, said modular support and advancement plane being geometrically configured for maintaining in a flat condition the part of the metal sheet supported thereby, a lifting and tilting device configured for varying the position of said structural frame, supporting said plurality of conveying modules, from a horizontal lying position to a tilted lying position in which said support and advancement plane tilted in a descending manner towards said bending machine and maintains in a flat condition the part of metal sheet supported thereby; repositioning and position correcting members configured for orienting and arranging in a correct position said metal sheet before the start of a bending cycle and configured for correcting, in the course of the bending cycle, the position of said metal sheet, by successive repeated repositioning, to impose on the latter a preset advancement trajectory towards and through said bending machine and reposition said metal sheet, several times through the cycle to maintain the geometry thereof correct.

2. Apparatus according to claim 1, wherein said base structural frame comprises a front end that is suitable for being connected rotatably, by a connection with hinge arms, to a base of said bending machine, to a zone placed below rollers of said bending machine, in which said connection with hinge arms acts as a fulcrum such that the lying position adopted by said support and advancement plane is tangential to a deformation curve of the metal sheet at a clamping zone between upper and lower pinching rollers of said bending machine.

3. Apparatus according to claim 1, wherein said modular support and advancement plane is of the roller type, in which said conveying modules comprise respective groups of rollers arranged, during operation, with rotation axes thereof transverse to the advancement direction of the metal sheet, said groups of rollers being motor-driven and drivable in a mutually synchronous manner.

4. Apparatus according to claim 1, wherein said base structural frame extends longitudinally with a total length and extends transversely, with respect to the advancement direction of the metal sheet, with a width, and in which each conveying module has a first dimension, considered orthogonally with respect to axes of respective rollers, which is about equal to, or less than, said width of said base structural frame, each conveying module having a second dimension, considered in a direction that is orthogonal to the first dimension, that is roughly the same as or greater than said width of said base structural frame.

5. Apparatus according to claim 4, wherein one or more conveying modules have a second dimension having a same value about the same as said width, and at least one further conveying module having the second dimension thereof is greater than said width.

6. Apparatus according to claim 5, in which said conveying modules have respective second dimensions having values that are higher, the greater the distance thereof is from said bending machine, such that said modular support and advancement plane defined by said conveying modules extends with a resting area for the metal sheet that grows progressively in zones further upstream of said bending machine to be able to support metal sheets that are very extensive and/or shaped in the form of a circular crown portion also with accentuated cone opening angles of the truncated cone structure to be obtained.

7. Apparatus according to claim 1, further comprising a lifting unit configured for lifting, and maintaining said metal sheet in a position detached from said modular support and advancement plane to enable said repositioning and position correcting members to move said metal sheet without there being relative sliding with said modular support and advancement plane.

8. Apparatus according to claim 7, wherein said lining unit comprises rack units defined by bar elements on which rolling elements are provided, of the wheel or sphere type, intended for coming into contact with, and lifting, the lower surface of said metal sheet facing downwards.

9. Apparatus according to claim 8, wherein each rack unit is movable, from a lower height, placed below the plane defined above by the conveying modules, to a height above said plane, each rack unit being vertically movable through a interspace defined between adjacent conveying modules, or between a roller and another roller of each conveying module.

10. Apparatus according to claim 1, wherein each of said repositioning and position correcting members comprises a pushing member provided with a resting head configured for abutting on, and pushing longitudinal edges of said metal sheet, said resting head being movable along a respective guiding crosspiece mounted on said modular support and advancement plane transversely to the advancement direction, there also being provided an actuating member for moving said resting head along the respective guiding crosspiece.

11. Apparatus according to claim 10, wherein said resting head is connected in an oscillating manner, with a certain degree of rotational freedom to be able to adapt to the position and tilt of a respective possibly bent longitudinal edge of metal sheet.

12. Apparatus according claim 1, further comprising an aligning device suitably for being placed upstream of said bending machine, and configured for moving a bent part of metal sheet exiting the bending machine to correct the curvature of the bent part and make a front edge of said bent part that has already traversed the bending machine match to a rear edge of the metal sheet about to enter the bending machine.

13. Apparatus according to claim 12, wherein said aligning device comprises a tilting table support that is rotatable around a rotation axis that is horizontal and transverse to said advancement direction of the metal sheet, on said tilting table support two lateral repositioning pusher arms being fitted that are movable parallel to said rotation axis to exert a pushing action on the two opposite longitudinal edges of said bent part of metal sheet to correct a possible misaligned position thereof, and in which on said rotatable tilting table support pusher rollers are fitted that are suitable for pressing on the outer surface of said bent part of a metal sheet to push the metal sheet to said bending machine.

14. Apparatus according to claim 13, wherein said pusher rollers are rotatable around respective axes arranged transversely to a longitudinal axis of said structural support frame and are supported by a bar element that can oscillate around an axis extending longitudinally to said base structural frame, such that said pusher rollers adapt to the lying of the outer surface of said bent part of metal sheet.

15. Apparatus according to claim 13, wherein from said lateral repositioning pusher arms respective pin elements project internally and horizontally on which respective wheel elements are mounted, said pin elements being movable, integrally with the respective lateral repositioning pusher arms, parallel to said horizontal rotation axis from a disengaged position outside a volume bounded by said bent part of metal sheet to an engaged position inside said volume, said wheel elements being suitable for going to rest on the inner surface of said bent part of metal sheet, in which a rotation of said tilting table support away from said bending machine with said pin elements in an engaged position is matched by a pressure action of said wheel elements on said inner surface to pull back said bent part of metal sheet in relation to said bending machine.

16. Apparatus according to claim 15, wherein at least one pusher arm of said lateral pusher arms is movable, by a hydraulic or equivalent driving device, along a direction orthogonally to the plane defined by said tilting table support, to move the respective wheel element towards/away from, said tilting table support, disaligning the wheel element from the opposite wheel element, to adapt to the geometry/lying of the surface of said truncated cone bent part of said metal sheet.

17. Apparatus according to claim 15, wherein said pusher rollers are rotatable around respective axes arranged transversely to a longitudinal axis of said structural support frame and are supported by a bar element that can oscillate around an axis extending longitudinally to said base structural frame, such that said pusher rollers adapt to the lying of the outer surface of said bent part of the metal sheet, and wherein also said lateral repositioning pusher arms are supported in such a manner as to be able to oscillate around said oscillating axis to adapt to the geometry/lying of the surface of said bent part of the metal sheet.

18. Apparatus according to claim 1, comprising position detecting sensors and distance measurers associated with said repositioning and position correcting members and arranged for detecting and monitoring the position of the longitudinal edges of said metal sheet during advancement, a control unit being also provided that is configured and programmed for: controlling a drive of said conveying modules and activating said lifting unit on the basis of signals of said position detecting sensors and distance measurers, and driving selectively and mutually independently said repositioning and position correcting members on the basis of the aforesaid signals of the respective position detecting sensors and distance measurers associated therewith.

19. Apparatus according to claim 18, wherein an aligning device comprises a tilting table support that is rotatable around a rotation axis that is horizontal and transverse to said advancement direction of the metal sheet, on said tilting table support two lateral repositioning pusher arms being fitted that are movable parallel to said rotation axis to exert a pushing action on the two opposite longitudinal edges of said bent part of metal sheet to correct a possible misaligned position thereof, and in which on said rotatable tilting table support pusher rollers are fitted that are suitable for pressing on the outer surface of said bent part of a metal sheet to push the metal sheet to said bending machine, and wherein said control unit is operationally connectable to said bending machine to control the drive of the rollers of said bending machine in a reciprocally correlated manner to: said conveying modules, said lifting unit, said repositioning and position correcting members, said aligning device.

20. Apparatus according to claim 18, comprising further distance measuring sensors to detect the position of the edges of the bent part of metal sheet, said control unit being configured and programmed for activating and controlling said aligning device on the basis of the signals supplied by said further distance measuring sensors.

21. Apparatus according to claim 1, further comprising a control panel with a graphic interface for programming said control unit and for entering dimensional and geometric data relating to said metal sheet and/or to the conical or cylindrical or truncated cone structure to be obtained by bending said metal sheet.

22. Method for supporting and advancing in a controlled manner a metal sheet towards and through a bending machine for forming a cylindrical or conical structure, in particular a truncated cone structure, comprising the steps of: arranging a plurality of conveying modules so as to generate a modular support and advancement plane adapted to the shape and dimensions of said metal sheet to be processed, placing on said modular support and advancement plane said metal sheet, driving repositioning and position correcting members acting on edges of said metal sheet for orienting and arranging said metal sheet in a correct position before the start of a bending cycle, driving a lifting and tilting device for arranging said support and advancement plane in a tilted lying position in a descending manner to said bending machine, whilst said metal sheet is maintained in a flat configuration, advancing said metal sheet by a portion through said bending machine to bend a front portion of said metal sheet, returning said support and advancement plane, and thus the part of the metal sheet supported thereby, to a horizontal lying position, resuming the advancement of said metal sheet through said bending machine and further driving said repositioning and position correcting members for correcting, during the bending cycle, the position of said metal sheet and imposing on said metal sheet a preset advancement trajectory through said bending machine.

23. Method according to claim 22, wherein after returning said support and advancement plane, and thus the part of metal sheet supported thereby, to a horizontal lying position and before resuming the advancement of said metal sheet through said bending machine, a rear roller of said bending machine is lifted that is opposite an insertion zone for inserting said metal sheet, so that it reaches and presses lightly, against the front portion of said metal sheet to cause the bending thereof as soon as the advancement of said metal sheet resumes.

24. Method according to claim 22, wherein, by position detecting sensors and distance measurers, the position of the edges of said metal sheet is also progressively detected during advancement by steps of said metal sheet and the advancement thereof is interrupted periodically to reposition and align correctly the metal sheet on the basis of a comparison of position signals supplied by said position detecting sensors and distance measurers with data relating to said preset advancement trajectory of said metal sheet.

25. Method according to claim 22, wherein before driving said repositioning and position correcting members, said metal sheet is lifted to remove the metal sheet from, and avoid relative sliding with, said modular support and advancement plane to prevent possible damage to a lower surface of said metal sheet.

26. Method according to claim 22, wherein the bent part of a metal sheet exiting the bending machine is moved transversely by an aligning device for correcting curvature of said bent part and making a front edge of said bent part match to a rear edge of the metal sheet that is about to enter the bending machine so as to restore a perfect circularity of the already bent metal sheet part and avoid the risk of the metal sheet collapsing through the force of gravity.

27. Method according to claim 26, wherein said conveying modules, said lifting unit, said repositioning and position correcting members, said aligning device, and the rollers of said bending machine are synchronized with each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention can be more easily understood and implemented with reference to the attached drawings, which show an exemplifying and non-limitative embodiment thereof, in which:

(2) FIG. 1 shows the apparatus according to the invention combined with a bending machine;

(3) FIGS. 2 and 3 are two side views of the apparatus in two different operating configurations;

(4) FIGS. 4 to 7 are different views of the apparatus according to the invention;

(5) FIGS. 8 to 11 are different views of the apparatus supporting a metal sheet to be processed;

(6) FIG. 12 shows a base structural frame and an aligning device which are part of the device;

(7) FIG. 13 shows conveying modules which form part of the apparatus and which are intended to be mounted on the base structural frame;

(8) FIG. 14 is a top view of the base structural frame;

(9) FIGS. 15 and 16 are respectively a top view and a side view of the conveying modules;

(10) FIG. 17 shows a elevation device and inclination forming part of the apparatus according to the invention;

(11) FIG. 18 shows a connection with hinge arms for the base structural frame;

(12) FIGS. 19 and 20 are respectively a perspective view and a top view of a member of repositioning and position correcting, in particular a pusher of the apparatus;

(13) FIGS. 21 to 23 are three different views of an aligning device forming part of the apparatus according to the invention;

(14) FIG. 24 shows the apparatus in another working configuration with the aligner device in a work position;

(15) FIG. 25 is an enlarged detail of FIG. 24;

(16) FIGS. 26 and 27 are two different interrupted perspective views which show the aligner device in the working position of FIG. 24;

(17) FIG. 28 is a top view of the apparatus in the operating configuration shown in FIG. 24;

(18) FIGS. 29 and 30 are two different views of a lifting group included in apparatus;

(19) FIG. 31 is a top view of the said lifting group;

(20) FIG. 32 schematically shows the lifting group in a retracted rest position in which it does not interact with a sheet resting on rollers of the conveying modules;

(21) FIG. 33 schematically shows the lifting group in a protruding position of work in which supports and maintains the metal sheet detached by the rollers of the conveying modules;

(22) FIGS. 34 and 35 are top views which show the operation of the apparatus with two sheets of different geometry, corresponding to two different angles of conicity of the truncated cone structures to produce.

DETAILED DESCRIPTION OF THE INVENTION

(23) With reference to the attached Figures, there is shown an apparatus 1 according to the invention suitable to be mounted on a bending machine 3 of the type with three or four or more rollers for the processing of metallic products, in particular for bending metal sheets 2 and to obtain cylindrical structures or truncated cone structures or multi radial.

(24) The apparatus 1 is used to support and advance in a controlled manner a metal sheet 2 and can also be connected to bending machines already existing, adapting itself with extreme ease to various configurations of machines that are already in use.

(25) The apparatus 1 according to the invention comprises a base structural frame 4 able to be positioned upstream of the bending machine 3, with respect to an advancement direction A.sub.D of the sheet 2, and a plurality of conveying modules M configured to be removably mounted on the base structural frame 4 so as to generate a plane P of support and advancement modular, that is to say configurable geometrically according to the shape and dimensions of the metal sheet 2 to be processed.

(26) As already mentioned, in conveying modules M can be moved laterally, that is to say in a transverse direction on the base structural frame 4 of structural base in such a manner that are “on the same axis” to the rollers near to the bending machine 3, is moved toward the outside that is always more, moving away from the bending machine 3, in order to be able to support correctly and safely also sheet very arched with circular crown portion shape.

(27) This sideways displacement can be carried out either “for long periods”, then moving the conveying modules M also in a “manual” manner, with the aid of lift trucks or overhead cranes, or “frequently”, by mounting this conveying modules M on wheels or slides which can allow the lateral translation facilitated (if pulled by a driven element such as for example a lift truck) or even “powered” autonomously.

(28) The structural base frame 4, which can be composed of two or more pieces that can be coupled, extends longitudinally with a total length L.sub.T which can be such as to be able to support and advance by the conveying modules M, sheets of considerable dimensions, e.g. long also about 20 meters or more. The width W of the base structural frame 4, measured transversely with respect to the direction of advancement A.sub.D of the metal sheet 2 is not greater than about 2.5 meters, so as to allow an easy transportability or displacement with normal devices without having to resort to systems of exceptional type transport.

(29) Each conveying module M comprises a supporting frame 16 (e.g. FIG. 13) inside which are supported the opposite ends of a group of rollers 8.

(30) The support frame 16 has in particular a quadrilateral shape with a size D1, in the longitudinal direction of the base structural frame 4, and another dimension D2 in the transverse direction with respect to the base structural frame 4.

(31) Each module M may have three or four rollers 8 or other desired number suitable for the specific requirements.

(32) The rollers 8 during operation are arranged so that their rotation axis transverse to the direction of advancement A.sub.D of the metal sheet 2. The groups of rollers 8 may be powered and driven in mutually synchronous manner.

(33) In particular, there is an electric motor 9 (or even more than one according to requirements) which drives, by means of a transmission element 13 of the belt or chain type or equivalent elements, simultaneously all the rollers 8 of the plane P of supporting and advancing.

(34) As mentioned above, and possible to diversify the dimensions of the various conveying modules M, for example by providing modules M more “narrow” in the vicinity of the bending machine 3, and modules M progressively more “wide” in the zones more upstream, that is more distant from the bending machine 3, and positioned in a manner offset with respect to the median longitudinal axis A.sub.L of the base structural frame 4, so as to efficiently support sheets 2 of arcuate shape also of considerable dimensions (sheets 2 very extensive and/shaped in the form of a portion of a circular crown with also accentuated opening angles of cone of the truncated cone structure to obtain), which would otherwise be arranged with a rear part not supported and laterally projecting in cantilevered position unstable and dangerous.

(35) The rollers 8 belonging to the modules M more adjacent to the bending machine 3 can thus have a length D2′ less than 2.5 meters, while the rollers 8 which are part of the modules M places more upstream may have a length D2″ higher, even more than 4 meters, and the rollers 8 of the conveying modules M in an intermediate position can have a length D2″ included between said extreme values.

(36) In substance, the dimension D2 of the modules M as measured orthogonally with respect to the advancement direction A.sub.D to or orthogonally to the longitudinal extension of the base structural frame 4, varies from a minimum value of about 2.5 mt or less (for modules M closer to the bending machine 3), to a maximum which can even exceed 4 mt (for modules M more upstream, farther away from the bending machine 3).

(37) Thanks to this modularity and differentiation dimensional of the conveying modules M, it is possible to construct a support and advancement plane P adapted to measure to the shapes and sizes of sheets 2 from time to time processable.

(38) The size D1 of each conveying module M, considered orthogonally with respect to the axes of the respective rollers 8 is about equal to or lower than the width W of said base structural frame 4, which is to say that does not exceed about 2.5 mt.

(39) Thanks to these characteristics, geometrical and dimensional, the conveying modules M can be easily transported and in an independent manner and not rigidly coupled to the base structural frame 4. Also in the case in which the module M has a dimension D2 relevant, well greater than 2.5 mt, thanks to the fact that the dimension D1 is less than about 2.5 mt allows it to be loaded without difficulty on a TIR, or container or other, orienting the rollers 8 in the longitudinal direction of the loading compartment.

(40) The apparatus 1 comprises a device 5 (or even more) of lifting and tilting configured to vary the position of the structural frame 4 supporting the conveying modules M, from a horizontal lying position G.sub.O to an inclined lying position G.sub.I in which the support and advancement plane P is inclined in a manner downwards toward the bending machine 3.

(41) The possibility of inclining the whole plane P for supporting and advancing maintaining the sheet resting in perfect flat configuration allows to bend directly the head portion or front edge portion of the metal sheet 2 already at the first (and possibly single) passage through the bending machine 3, as will be better described hereinafter.

(42) The device 5 of lifting and tilting is independent and disengaged from the bending machine 3 to prevent of transmitting them external loads, not direct and due to the curvature of the sheet. The device 5 of lifting and tilting is shaped so as to rest on the floor or on a foundation or independent frame, such as to allow a large lifting and tilting of plane P of support and advancement with motorized rollers.

(43) According to a form of embodiment which is not limiting, the device 5 of lifting and tilting has a pantograph structure with bar elements mutually connected and articular and suitable drive actuators 14, as better visible in FIG. 17.

(44) The pantograph shape of the device 5 of lifting and tilting makes possible to optimize the spaces under the base structural frame 4, and allows to avoid expensive and deep trenches which would be necessary for housing other types of lifting devices more bulky.

(45) The base structural frame 4 comprises a front end which is suitable to be connected rotatably, by a connection with hinge arms 7 to a base of the bending machine 3, to a region located below or laterally to the rollers 15 of the bending machine 3.

(46) The connection with hinge arms 7 acts as a fulcrum in such a way that to a lifting action on the part of the device 5 of lifting and tilting corresponds to a rotation of the structural frame 4; the connection with hinge arms 7 causes the lying plane taken from the plane P of support and advancement is maintained constantly tangential to the curve of deformation ideal assumed from sheet 2 at the clamping zone between the upper and lower pinching rollers 15 of the bending machine 3.

(47) In other words, the roller support plane P is pivoted in a point of articulation “ideal” for its inclination, preferably located inside the volume occupied by the bending machine 3 below the pinching rollers 15, and in any case so that, when the sheet 2 is raised in a manner inclined upwards and supported to allow the curvature of its front edge (as described later), its lying plane remains tangent to the line of curvature imparted by the rollers of the bending machine.

(48) The apparatus 1 comprises realignment members 6 devices, also called repositioning and position correcting members configured to direct and arrange in a correct position the sheet 2 before the start of a bending cycle. The members for repositioning and position correcting are especially configured to correct, during the bending cycle, the position of the metal sheet 2, by means of successive repeated repositioning, to make it a predetermined trajectory of advancement T toward and through the bending machine 3 and reposition it several times during the cycle in order to keep the correct geometry.

(49) Each of repositioning and position correcting member comprises a pushing member 6 which has a resting head 20 configured to abut, and push the longitudinal edges E of said sheet 2. The pushing members 6 are mounted in such a way as to be able to act laterally on both sides of plane P of support and advancement. Two pushing members 6 are provided to one side and two further pushing members 6 to the opposite side of plane P of support and advancement. However it is possible to provide a different number of pushing members 6 on each side of the plane P of support and advancement, according to needs.

(50) The resting head 20 is movable along a respective guide crosspiece 21 connected to the plane P of support and advancement transversely with respect to the direction of advancement. The pushing member 6 comprises a actuator member 22 arranged to move the resting head 20 along the respective guide crosspiece 21.

(51) The actuator 22 can comprise an hydraulic double acting cylinder, fed by a suitable hydraulic circuit. Alternatively, the actuator 22 can be of the pneumatic or electric or of another equivalent type.

(52) Each pushing member 6 is mounted with the crosspiece 21 of guide below the plane tangential to the rollers 8 along which lies the metal sheet 2 in such a way as not to interfere therewith; instead, the resting head 20 is connected to the crosspiece 21 of guide in cantilevered position upwards laterally with respect to the rollers 8, so as to be able to reach and push the longitudinal edges E of the sheet 2.

(53) The resting head 20 (better shown in FIGS. 19 and 20) is connected by means of a pin to the support connected to the actuator 22 so as to be oscillating around a vertical axis 23. In this manner the resting head 20 has a certain rotational degree of freedom so as to be able to adapt, in self-aligning manner, to the position and inclination of the respective longitudinal edge E eventually curved of sheet 2.

(54) To each pusher member 6 is operatively connected to a sensor 36 for detecting position and distance meter, or, for the sake of simplicity of illustration, distance measurement sensor, arranged to detect and monitor the position of each longitudinal edge E of the sheet metal 2 during the advancement.

(55) It is also provided a Uc control unit, internally comprising a process logic module (PLC) having a suitably microprocessor programmed for activating and controlling several components of the apparatus 1. In the Uc control unit there is a software of numerical calculation and control of the inclination and positioning of the pusher members 6.

(56) To the Uc control unit are operatively connected various components of the apparatus 1 and is configured and programmed to control the actuating of the conveying module M and for selectively activating and mutually independent pusher members 6 on the basis of the signals of the above distance measurer sensors 36, to correct the position and therefore the trajectory of advancement of the sheet 2.

(57) The pusher members 6 being also managed completely automatically by the numeric control and software of the Uc control unit, the pusher members 6 are therefore of “intelligent” type.

(58) The operation of the Uc control unit will be described in more detail below.

(59) The apparatus 1 further comprises a lifting group 10 (best shown in FIGS. 29 to 33) configured to lift the metal sheet 2 of a small amount sufficient to keep it in a position detached from the plane P of modular support and advancement, so as to enable the pusher members 6 to correct the position of the metal sheet 2 off shifting it without relative sliding with the rollers 8 of plane P of support and advancement.

(60) The lifting unit 10 is operatively connected to the Uc control unit which enables the operation of the lifting unit 10 in a coordinated manner to the actuation of the rollers 8 and the movement of pushing members 6.

(61) The lifting unit 10 comprises one or more rack units 11, defined from bar elements on which are provided rolling elements 12 of the roller or ball type, intended to come into contact with and to lift, the lower surface of the metal sheet 2 facing downwards.

(62) The rolling elements 12 which can be self aligning, roll under the sheet 2 to them superimposed, thus avoiding the sliding friction.

(63) The rack unit 11 is movable from a lower level (retracted rest position), located below the plane defined by the upper conveying modules M (shown in FIG. 32), at a higher level (protruding position of work), situated above said plane (shown in FIG. 33), in which the metal sheet 2 is separated by the rollers 8 of the plane P of support and advancement.

(64) The rack unit 11 is therefore of the disappearing type is in the lowered position of rest does not interfere with the sheet metal 2 moving forward.

(65) The rack unit 11 can move vertically through an interspace defined between adjacent conveying modules M and between a roller 8 and another roller 8 of each conveying module M.

(66) The rack unit 11 is able to be actuated by means of a suitable pneumatic or electric or hydraulic or another equivalent device.

(67) By means of the lifting unit 10 it prevents the metal sheet 2 moved by the pushing members 6—in transversal direction with respect to the longitudinal axis of the structural frame 4 of the support plane P—flow with abrasive sliding along the rollers 8 and it is therefore avoided of damaging the lower surface of sheet 2.

(68) The apparatus 1 further comprises a aligner device 30 adapted to be placed upstream of the bending machine 3, and configured to move a bent part B of sheet metal exiting to the bending machine 3 for correcting the curvature and to collimate a front edge E.sub.F of this bent part B which has already passed through the bending machine 3 to a rear edge E.sub.R of the sheet metal in imminent entry into the bending machine 3, as is better shown in FIGS. 26 and 27.

(69) The aligner device 30 is conceived as part of the apparatus 1, therefore autonomous and independent from the structure of the bending machine 3, and thus is connected to the base structural frame 4.

(70) However, in case of construction difficulties or logistic or for other needs, the aligner device 30 can be configured in such a manner as to be able to be connected directly to the bending machine 3, or connected to earth in a specific intermediate region between the base structural frame 4 and the bending machine 3. In the latter case the aligner device 30 is in any case operatively connected and operated in a coordinated manner to the remaining part of the apparatus 1.

(71) The aligner device 30 comprises a tilting table support 31, the support 31 is rotatable around an horizontal rotation axis X that is orthogonal horizontal with respect to the longitudinal axis A.sub.L of the base structural frame 4 of base and is therefore, transversal to the direction of advancement A.sub.D of the metal sheet 2.

(72) On the tilting table support 31 are mounted two repositioning lateral arms-pushers 32 that are movable independently the one from the other in a direction that is parallel to the aforesaid axis of rotation X to exert thrusts on the two opposite edges of bent part B of sheet metal for correcting a possible axially offset position.

(73) The pusher arms 32, in addition to operating in alignment step of bent part B of sheet metal (therefore when the tilting table support 31 is rotated in a raised position with respect to the horizontal lying position) can cooperate with the other pushing members 6 of repositioning (therefore with the tilting table support 31 in the horizontal position) in initial squaring step of the metal sheet 2 and also in the following steps of repeated-positions for the correction of the trajectory of advancement of the sheet 2.

(74) On the rotatable tilting table support 31 are mounted pusher rollers 33 suitable for press on the outer surface of the bent part B of sheet metal to push it in a direction that points toward the bending machine 3.

(75) The pusher rollers 33 are supported in a tilting way by the aligner device 30, that is to say that they are mounted on a bar element 25 that can oscillate around an axis X.sub.B of oscillation which extends longitudinally with respect to the base structural frame 4. This makes the pusher rollers 33 self aligning, that is to say match the lie of the outer surface of bent part B of the sheet 2.

(76) By repositioning lateral pusher arms 32 project internally and horizontally respective pin elements 34 on each of which is mounted a respective wheel element 35.

(77) The pin elements 34 are movable integrally with the respective pusher arms 32 of repositioning in a parallel direction to the aforesaid axis of rotation X horizontal, from an external disengagement position with respect to the volume held by bent part B of sheet metal to an engaging position inside this volume. The wheel elements 35 are adapted to rest on the inner surface 37 of the bent part B of sheet metal.

(78) At least one of lateral pusher arms 32, in particular the pusher arm 32′ (FIGS. 21, 23, 26), intended to interact with the region with a larger diameter of the truncated cone structure, is also provided with a translational degree of freedom in the direction Z (FIG. 23) orthogonal with respect to the plane of the tilting table 31 of the aligner device 30; in other words, the pusher arm 32′, and with it the respective pin element 34′ and wheel element 35′, can be moved along the direction Z orthogonally in moving towards/away from the plane defined by aligning device 30, for instance through a hydraulic cylinder or other suitable and equivalent operating element. Thanks to this configuration, it is possible misaligning the pusher area 32′ with respect to the other pusher arm 32 closer to the tilting table 31 in order to allow the respective wheel element 35′ can come in contact with the curved zone of sheet metal that since provided with a larger diameter, is closer to aligner device 30 with respect to the opposite zone of sheet metal having smaller diameter. In other words, while in the case of curvature of a cylindrical structure the two wheel elements 35 and 35′ are positioned at a same distance from the plane of the tilting table 31 and thus lie on a plane which is parallel to the axes of the rollers of a bending machine, in the case of a truncated cone structure (which therefore would have opposite areas of edge at a different distance from the aligner device 30), thanks to the adjustment in the direction Z orthogonal to the tilting table 31, it is possible to adjust the pusher arm 32′ so that the two wheel elements 35, 35′ are on a suitably inclined plane and parallel to the directrix of the truncated cone structure on which it is necessary to perform the aligner device 30 in order to restore the perfect circularity and position of bent part B of sheet metal.

(79) The pusher arms 32, thanks to the aforesaid translational degree of freedom in direction Z adapt effectively to the truncated cone shape of bent part B of sheet metal. The pushing to and/or reverse pulling action of bent part B of metal sheet with respect to the bending machine 3, and also the transverse displacement of the front edge E.sub.F and its alignment to the rear edge E.sub.R are improved. The precise alignment of the front edge E.sub.F with the rear edge E.sub.R allows a welding to the rules of the art, which causes the two bases of the truncated cone lie on two planes regular, in the absence of undesired stepped zones that would otherwise be generered by an imperfect transverse alignment of the said two head edges of the sheet.

(80) During operation, at a rotation of the tilting table support 31 moving away from bending machine 3, that is to say at a rotation which tends to bring the tilting table support 31 toward its the horizontal lying position, achieves a pressure action of the two wheel elements 35 on the inner surface 37 (with the pin elements 34 in engagement position). The aforesaid action of pressure is such to pull back the bent part B of the sheet metal.

(81) Therefore, with the wheel elements 35 which can push in a rearward direction with the pusher rollers 33 that can push in the front direction, and with the two pusher arms 32 of repositioning (which support the wheel elements 35) that can push transversely from opposite directions toward the inside of the apparatus 1, it is possible to apply to the bent part B of the sheet any desired movement intended to give the correct shape and position.

(82) The action of pull of the bent sheet serves to avoid its natural tendency to collapse by gravity through its own weight or intervenes for slightly “re-open” the bent sheet eventually already partially collapsed.

(83) The aligner device 30 avoiding a superposition of front and rear areas of sheet metal (phenomenon of “overlapping” dangerous if in input between the rollers 15 of the bending machine 3), and acts to correctly align the front edge E.sub.F to the rear edge E.sub.R of the bent sheet metal.

(84) According to a further possible embodiment implementation is provided that the pusher arms 32 are supported in such a way as to be also oscillating around the axis X.sub.B of oscillation described above.

(85) The pusher arms 32 and said pusher rollers 33 can then be mounted on the same shared bar, or on different bars, so as in any case to be tilting around the aforesaid axis X.sub.B of oscillation.

(86) Also in this case, thanks to this possibility of a tilting movement around the aforesaid axis X.sub.B of oscillation, the aligner device 30 is able to rest adapting to effectively bent part B of sheet metal, constantly maintaining both pusher rollers 33 in contact with the metal plate. The pusher arms 32, thanks to the aforesaid degree of freedom in oscillation, are also self aligning, and adapt effectively to the truncated cone shape of bent portion B of sheet metal. Also in this version, is improved the pushing to and/or inverse pulling of bent part B of metal sheet with respect to the bending machine 3, and also the transverse displacement of the front edge E.sub.F and its alignment to the rear edge E.sub.R. The results already mentioned above are thus achieved, that is to say a precise alignment of the front edge E.sub.F with the rear edge E.sub.R which allows a welding geometrically precise and free of imperfections and undesired stepped zones.

(87) In the FIGS. 25, 26 and 27 is shown by way of example the operation of the aligner device 30 which acts to bring the bent part B of sheet metal of a wrong configuration C″ of shape and position, to a correct configuration C″ of shape and position.

(88) The aligner device 30 can also be combined with an optical monitoring device such as a television camera, useful to the operator for perfectly displaying the current position of two edges E.sub.F, E.sub.R, and control more easily the device 30 also remotely, in conditions of total safety, shielded from dangerous work areas.

(89) Thanks to the intervention of the aligner device 30 possible for an operator to perform more easily the spot welding, with short welding beads (“tack welding”) to stiffen the structure before the extraction from the bending machine 3.

(90) Also the aligner device 30 can be controlled by the Uc control unit and is moved in a synchronized manner with the rollers of the bending machine 3 and/or with the conveying modules M and with the lifting and tilting device 5.

(91) Further distance measurement sensors associated to the aligner device 30 may be provided and arranged to detect the position of the edges of bent part B of sheet metal; in this case the Uc control unit is configured and programmed for activating and controlling the aligner device 30 on the basis of the signals supplied by said additional sensors.

(92) The apparatus 1 further comprises a control panel Pc with a graphical interface for the programming of the Uc control unit and for the input of dimensional and geometric data relative to the sheet 2 and/or to the conical or cylindrical or truncated cone structure to obtain by means of the bending process of the metal sheet 2.

(93) Is now described the operation of the apparatus 1 according to the invention.

(94) An operator types on the graphic interface of the control panel of Pc the geometric/dimensional data of the truncated cone structure to produce (or of the metal sheet 2 to be bent to generate this truncated cone structure).

(95) The software calculates the geometry of the plane development of the truncated cone structure, that is to say determines the geometry of the starting flat sheet metal 2, and determines as such sheet 2 should be placed on the plane P of roller support so that it has its front edge E.sub.F (“inlet”) perfectly parallel to the axis of the rollers 15 of the bending machine 3.

(96) The control unit Uc then calculates the positions in which the pushing members 6 must be arranged to impose to sheet 2 the starting position and orientation above indicated.

(97) The control unit Uc, once calculated the required starting position of the metal sheet 2, commands the pusher members 6 to move with their resting heads 20 in position as far as possible from the plane P of support, making it completely free the resting surface so as not to hinder the operations of transfer and laying of a sheet 2 on the plane P of support and advancement.

(98) In this way, a metal sheet 2 can be laid easily and with more quickly on the plane P of support, without however having to worry about its correct orientation, the latter being achieved automatically by the apparatus 1.

(99) Once the metal sheet 2 is laid in fully random position on the plane P of support, the step of automatic alignment, or squaring, of the front edge E.sub.F of sheet 2 to the rollers 15 of the bending machine 3 at the beginning of the cycle occurs.

(100) The control unit Uc (where required to avoid scratches or other damages to the surface of the sheet metal) can control the lifting of the lifting group 10 that therefore detaches the sheet 2 by the rollers 8 of the surface P of support in order to avoid slippage with friction in the subsequent squaring operation of sheet 2.

(101) To a start command imparted by the operator by means of the control panel Pc, the control unit Uc automatically activates the pushing members 6 currently in the parking position and total disengagement by controlling them to move toward the sheet metal 2 until they reach the position each associated to the correct arrangement of the metal sheet and hence corresponds to have its leading edge perfectly parallel to the axis of the rollers of the bending machine 3.

(102) The pushing members 6 then enter in contact with the edge/s E of the sheet 2 and the move until it is taken to the ideal position with the front edge E.sub.F perfectly parallel to the axis of the rollers 15 of the bending machine 3.

(103) At this point the lifting unit 10, if lifted above, is lowered, and activated the conveying modules M, the front edge E.sub.F of the sheet metal 2 is advanced to be inserted and clamped between the rollers 15 of the bending machine 3.

(104) Once gripped the front edge E.sub.F1, and initiated rising of the front roller of the bending machine (the immediately in front of the apparatus 1 to roller conveyor) which begins to lift and folding the metal sheet to bending it, is also activated the lifting and tilting device 5 which transfers the sheet 2 from the horizontal lying position G.sub.O to the inclined lying position G.sub.I. In particular, the lifting and tilting device 5 is preferably synchronized lifting and tilting and is actuated simultaneously with the upward movement of the front roller of the bending machine.

(105) The lifting of the support plane P is accompanied also by a raising of the tilted table support 31 which is then moved synchronously to the plane P of support, in elevation and in lowering. The sheet 2 is then made to advance by a portion through the bending machine 3, thus be bent immediately the front portion of the sheet 2.

(106) Subsequently, the front roller of the bending machine 3 (the immediately in front of the apparatus 1 to roller conveyor), after be risen to fold the front edge of the sheet metal, begins to fall, to bring the part of the metal sheet still upstream, not bent in the horizontal lying position while in the manner synchronized, is also lowered the support plane 4 toward the horizontal lying position G.sub.O so as to keep the metal sheet always in a perfect resting on the whole of its length; can thus begin advancing in automatic mode “semi-continuous” of the sheet 2 through the bending machine 3.

(107) The sheet 2 is made to advance, linearly, of a advancement distance calculated by the numeric control and then be rotated slightly, and so on.

(108) After having restored the support and advancement plane P and therefore the part of sheet 2 supported thereby horizontal lying position G.sub.O and before starting again the advancement of the sheet metal 2, is raised a rear roller 27 (opposite to the area of insertion of the metal sheet 2) of the bending machine 3 (FIG. 3), until it reaches and slightly presses the front portion of sheet to cause its bending, as soon as this will advance.

(109) The operator may decide to set this advancement distance at will or through the aid of the sensors 36 detecting position and distance measurers, is continuously monitored the advancement of the lateral curve inner edge; as soon as it is detected that such lateral curved inner edge is approaching too close to boundary region of ends of the rollers 15 of the bending machine (with the risk of collision with the structure of the calender 3), the control unit U.sub.C stops the rotation of the rollers 15 of the bending machine 3 and of the rollers 8 of the plane P of support.

(110) If necessary, is loosened the pressure of the rollers 15 of the bending machine 3 on the sheet 2 which is then released and free to be able to be rotated by the pushing members 6 and in those cases in which it is necessary, not before having detached the sheet 2 from the resting rollers 8 by the lifting assembly 10 in order to prevent the relative sliding with sliding friction.

(111) The control unit U.sub.C by means of a comparison of the signals of the sensors 36 position detectors and distance measurers with reference data programmed and saved in memory, sends appropriate commands to pushing members 6 which come into contact with the edge/s of the metal sheet 2 and the once again displace until it is brought again into the ideal position with the generatrix in that moment close to the rollers 15 of the bending machine 3 perfectly parallel to the axis of the rollers 15 so as to rotate the sheet 2 in the correct position.

(112) In this way, the generatrix of the metal sheet 2 close to the rollers 15 of the bending machine is arranged coaxially to the axis of the rollers 15 in the same manner previously followed for the initial step of alignment/squaring of sheet 2. In substance, the sheet is subjected to a small rotation, without translation, while the rollers 15 of the bending machine 3 are stationary.

(113) Once this operation is finished, the control unit U.sub.C returns the pushing members 6 in the position of “parking”, distant from the rollers 8 of the support plane P, to leave totally free movement of advancement of the sheet metal 2, while the rollers 15 of the bending, machine 3 in the manner synchronized, are reported in gripping position of the sheet 2.

(114) The control unit U.sub.C then restarts the rotation of the rollers 8 of the support plane P, determining the advancement of a subsequent section of metal sheet 2 in the bending machine 3.

(115) The above described steps are repeated for a number of times required to feed the whole sheet 2 in the bending machine 3.

(116) To form the truncated cone structure automatically the pushing members 6 repeatedly intervene to rotate slightly from time to time the sheet metal in the form of circular crown portion, that is to say exert subsequent and repeated thrust actions on the edges E longitudinal (bent) of the sheet metal 2, arranging it several times along the whole extension thereof. The repeated and well calibrated thrust actions report from time to time the different generatrices in a position coaxial to the axis of the rollers of the calender 15, so as to keep the coherence with the desired geometry of the frustum of the cone.

(117) In FIGS. 34 and 35 is shown the operation with two different examples of geometry of the sheet metal, respectively meant to form a truncated cone structure with a small angle of conicity (FIG. 34), and of a truncated cone structure with a large angle of conicity (FIG. 35).

(118) In the case of FIG. 35, the metal sheets requires a greater number of interventions of repositioning (symbolically represented by arrows F1) carried out by the pushing members 6: the dashed line the|L.sub.T1 represents the path followed by the rear edge Sp (placed lower than in the Figures). In FIG. 35 it can be noted that the dashed line LTI comprises of the horizontal portions separated by respective vertical portions: each horizontal tract symbolizes a respective linear advancement portion of the metal sheet 2 along the support plane P, and thus parallel to the longitudinal axis A.sub.L of the support structural frame 4, while each vertical portion in figure represents a movement of the edge Sp in a direction transverse to the longitudinal axis of the support structural frame 4.

(119) In the case of FIG. 34 is evident the smaller number of interventions of repositioning (symbolically represented by arrows F2) that the pushing members 6 are called to carry out due to the smaller angle of conicity which characterizes the truncated cone structure to produce. Consequently, the respective dashed line L.sub.T2 has horizontal portions longer, separated by a smaller number of vertical portions.

(120) The just described sequence of repeated repositioning may take place according to two possible modes: a preset mode, i.e. programmed beforehand in the control unit U.sub.C, or in a completely automatic way, that is to say entrusting to distance measurement sensors communicating with the control unit U.sub.C the task of monitoring continuously in real time the position of the edge of the sheet metal 2 during the advancement by activating from time to time the actions of repositioning of the metal sheet 2.

(121) Both in a mode to the other, the bending process takes place with total safety for the operators, without the possibility of mistakes and with processing times considerably reduced if compared to the traditional systems of manual type based on an approach of estimation and approximation entrusted to the experience of the operators.

(122) As the sheet 2 passes through the bending machine 3, a always greater fraction of it is then curved. A suitable support 40 with rollers 41, (belonging to the bending machine 3 is to this pivotally connected downstream of the rollers 15 of calendering) is operated to help the bent part B of the metal sheet to follow the trajectory upward.

(123) A further aid for maintaining in position the bent part B of metal sheet is provided by a horizontal arm 43 which is mounted in a cantilevered on and slides vertically along a vertical guiding upright 42 and is provided with rollers 44 able to resting receive the inner surface the higher part of bent part B of the sheet.

(124) When a relevant fraction of the metal sheet 2 has been bent, the aligner device 30 intervenes which restores the perfect circularity of bent part B, prevents any risk of collapse by gravity and remedies to possible misalignments of the front and rear edges E.sub.F and E.sub.R of the metal sheet 2 which are thus caused to match to one another as previously illustrated.

(125) At this point one operator can perform the point welding (“tack welding”) to stiffen the structure before the extraction from the bending machine 3.

(126) It is evident that the perfect circular configuration thus made saves the operators many difficulties in subsequent assembly, when it is necessary welded one above the other the variants truncated cone parts obtained to construct the wind tower. In fact, if occur during assembly a vertical misalignment (i.e. a region of step in the coupling interface of the two edges, with the centers of the two circumferences of the two respective bases of the truncated cone not aligned) would make the welding of the subsequent truncated cone extremely difficult, forcing long complicated and unproductive correction actions with a consequent loss of time and losses of productivity, unacceptable in a sector extremely competitive as to wind sector.

(127) Thanks to the efficiency of the control unit Uc and of the software with which it is loaded, and thanks to the efficiency of the pushing members 6 of aligner device 30 and other parts of the apparatus 1 is a bending process optimized, free of risks of error and totally safe for operators. The excellent results in terms of uniformity of the diameters of curvature in a single step in a bending machine 3, therefore in a single direction of passage, always makes superfluous a step of “gauging” (also known as “re-rolling”) of truncated cone structure obtained.

(128) The apparatus 1 thus allows a intensive production and efficient with a degree of repeatability on dimensional and geometric characteristics of the curved structures that are obtained that may be difficulty achieved by the current systems of curvature.

(129) From what has been said and shown in the attached drawings, it is evident that what is provided is a method and an apparatus 1 by means of which are possible to provide in a single unidirectional passage in a bending machine 3 a truncated cone structure, with a great speeding up of the bending cycle, then reduction of dead times and in conditions of total security for the operators.

(130) Finally the apparatus 1 makes it possible to avoid to subject the sheet 2 to undue stresses and deformations and to achieve a considerable improvement in the geometric precision and uniformity of the structures obtained, thereby facilitating the subsequent processing of the truncated cone structures and reducing in general the possibility of error and working inaccuracies.

(131) Moreover, the modular nature or modularity of plane P of support and advancement on the basis of the dimensions and shapes of the metal sheets from time to time processable, ensures an effective action of support distributed and uniform over the entire area of the sheet metal, regardless of the shape and size of the latter. Therefore a technical solution is extremely versatile that also facilitates the shift operation or transport of the apparatus 1.

(132) It is also understood that what has been said and shown in the attached drawings has been given purely in order to illustrate the general features and the method, as well as of a preferential form of embodiment of the apparatus 1 according to the present invention.

(133) Other modifications or variations may be made to the entire apparatus 1, or its parts, and to the respective operating method, without thereby deviating from the claims.