Machine for punching and bending metal sheets

Abstract: There is described a machine for machining metal sheets, which comprises a bending machine (1) for bending sides of a metal sheet (50) and a manipulator-rotator (3) that is mobile in relation to the bending machine (1) for automatic positioning of the metal sheet (50) during bending. The machine comprises at least one punching press (21, 30) for punching said metal sheet (50), that is served by said manipulator-rotator (3) so that said manipulator-rotator (3) is utilised for automatic positioning of the metal sheet (50) both during bending and during punching of the metal sheet (50).

Description: The present invention refers to a machine for machining metal sheets, according to the preamble of claim 1 (see for example WO-A-94/01234). In particular the invention refers to a machine for punching and bending metal sheets. Machining of metal sheets requires various distinct operations, in particular punching of the sheets, possibly shearing of the comers, and bending to form a panel having the desired shape. Currently there are available punching machines, comer shearing machines and bending machines also known as "panelling machines" for bending sheets. Such machines are distinct from each other. This obviously involves high purchase costs, and slowness of the machining process, since the metal sheets that are not machined yet, or semi-finished or finished ones must be loaded and unloaded from a machine in order to go on to the following machining stage. In view of the state of the art described, object of the present invention has been to provide a single machine for machining metal sheets, which is capable to carry out the several operations that are currently carried out by different machines. According to the present invention, such object has been attained by a machine for machining metal sheets according to claim 1. The present invention provides for a single machine capable to carry out all the operations necessary for machining metal sheets. As compared with the known technique, in which lines of different machines such as punching and bending machines are provided, the machine according to the present invention has a lower cost: all the machining stages are concentrated in a single machine. The machine according to the invention has also a reduced dimension as compared with a line with different machines, and the power consumption is also lower. In addition machining time is also reduced. The characteristics and the advantages of the present invention will become evident from the following detailed description of an embodiment thereof, that is illustrated as example in the enclosed drawings, in which: Figure 1 is a comprehensive axonometric view of an embodiment of a machine according to the present invention; Figure 2 is a sectional view according to a longitudinal plane of the machine in Figure 1; Figure 3 shows a detail of Fig. 2 in a magnified scale; Figure 4 is a sectional view along line IV-IV of Figure 2; Figure 5 shows a detail of Fig. 4 in a magnified scale; Figures 6 to 13 show the machine of Figure 1 in plan, in a sequence of machining stages of a metal sheet. With reference to the drawings, in particular to Figures 1, 2 and 4, a machine for machining metal sheets comprises a bending or "panelling" machine 1, known per se, which has a front access opening 20 and comprises at such opening a lower row 10 of so-called bending counterblades, an upper row 11 of blank holder blades, the blank holder blades 11 being mobile so that they cooperate in a known way with the bending counter-blades 10 in order to keep tight an edge of a metal sheet (not shown in these first figures), and, inside the opening 20, a mobile blade holder block 12 that has at its ends lower bending blades 13 and upper bending blades 14. Before the opening 20 of the panelling machine a work table 15 is located. In a known way, near the opening 20 of the panelling machine the work table 15 comprises a table 2 for correct positioning of the metal sheets to be subjected to bending and for unloading of the bent panels at the end of machining. The work table 15 is divided into two parts, that are distanced so as to centrally define a rectilinear path 18 for the movement of a manipulator-rotator carriage 3, also known per se. The manipulator-rotator carriage 3 comprises a substantially "⊃" shaped structure, with concavity toward the panelling machine 1, as visible in Figure 2. At the two ends of the "⊃" shaped structure a pair of jaws 16, 17 is mounted, of which the lower jaw 16 is fixed in height, but can rotate as being connected with a shaft 19 that is operated in turn by a motor not shown; the upper jaw 17 is instead idle to rotation, but it is vertically slidable still by action of an opportune drive, for example a hydraulic or pneumatic cylinder not shown. The pair of jaws 16, 17, including the controls for the lifting/lowering of the jaw 17 and for the rotation of the jaw 16, makes up the rotator. The upper jaw 17 can descend toward the lower jaw in order to hold the metal sheet to be machined, and therefore the rotation of the lower jaw 16, which drags the upper idle jaw 17, allows to rotate the metal sheet on the work table 15. Along the work table 15, at a first distance from the panelling machine 1, a first punching press 21 is arranged transversally to the direction of the movement of the manipulator 3. The press 21 comprises two C-shape facing half portals 25, with concavities toward the inside of the work table 15 and whose throats are substantially at the level of the work table 15. The two C-shape half portals are transversally mobile with reference to the direction of movement of the manipulator carriage 3 on two respective pairs of guides 22, 23 by means of a respective system of motion transmission, not visible in the drawings. As it can be seen in the detail of Figure 3 at the free upper end of each C-shape half portal a punch holder block 24 is mounted, inside which punching tools 26 are located, each being independently controlled from the rest by means of a respective hydraulic or pneumatic cylinder 27. At the free lower end of each C-shape half portal instead a matrix holder block 28 is mounted inside which respective matrixes 29 are housed for the punching tools 26 that are vertically aligned with the same. The punching press 21 is therefore of the commonly called "multi-press" or "multi-punch" type, since it is provided with more punching heads that can work independently from the other ones. However this is not a limitation of the present invention, in that the press 21 could also be of another type, for example of the so-called "mono-press" or "mono-punch" type. Downstream of the first punching press 21 in the direction of movement from the panelling machine 1, at a second distance from the latter, a second punching press 30 is provided, that is also arranged transversally to the direction of the movement of the manipulator 3. The second press too, as the first press 21, comprises a pair of C-shape facing half portals 31, with concavities toward the inside of the press 21 and whose throats are substantially at the level of the latter. The two C-shape half portals 31 are transversally mobile with reference to the direction of movement of the manipulator 3 along two respective pairs of guides 32, 33. As it can be seen in Figures 3, 4 and 5, at the free upper end of each C-shape half portal 31 a punch holder block 34 is mounted, inside which a single punching tool 35 is housed, that is controlled by means of a respective hydraulic or pneumatic cylinder 36. At the free lower end of each C-shape half portal 31 a matrix holder block 37 is mounted inside which a respective matrix die is located that is vertically aligned with the respective punching head. The second punching press is therefore of the commonly so-called "mono-press" or "mono-punch" type. However, this should not be intended as a limitation of the present invention, in that the second press, as also the first one, could be indifferently of the mono or multi-punch type, according to the type of machining that must be carried out on the metal sheets. Another characteristics of the machine shown in the drawings that must not be interpreted in a limiting way for the present invention is the number of punching presses that are arranged along the work table 15, that could be only one, or else more than two. It should be noted that even though the two punching presses 21 and 30 shown in the drawings each comprise two C-shape half portals, this does not represent a limitation for the present invention: both punching presses, or only one of them, could comprise a single C-shape half portal, indifferently placed on one side or the other of the manipulator-rotator carriage 3, even if this solution requires more operations of movement of the metal sheet for the complete machining of the same. Figures 6 to 13 illustrate, with more schematic plan views of the machine than the previous ones, a possible complete machining cycle of a metal sheet. In particular, in Figure 6 there is shown a first stage of a possible machining cycle, consisting in feeding of a metal sheet 50, having generically rectangular shape, on the work table 15. Feeding can be done manually or, as more commonly, automatically, by means of known feed systems. After having laid the sheet 50 on the work table 15 and having properly positioned it, the manipulator-rotator carriage 3 moves toward the panelling machine 1 until the two jaws 16, 17 get substantially on the vertical line of the centre of the sheet 50. Then, the upper jaw 17 comes down and together with the jaw 16 holds the sheet 50 tight. As shown in Figure 7, the manipulator-rotator carriage 3 therefore gets back toward the two punching presses 21 and 30. If for example the metal sheet 50 must be comer sheared, the carriage 3 moves back until the two back comers of the sheet are brought in correspondence of the second press 30; the latter, by means of cross sliding of the two half portals 31, brings the free ends of the two half portals 31 above the corners of the sheet to be sheared, so that the two punches 34 can simultaneously proceed with the shearing of the two back comers. At the same time, the two half portals 25 of the first press 21 slide transversally in order to bring their free ends with the punch holder blocks in the desired position for the sheet, and therefore to go on with the punching where required. Therefore, as shown in Figure 8, the sheet 50 is rotated by 180° by means of the rotator (jaws 16, 17 and operation of the lower jaw 16), so that now under the two punching presses 21, 30 there is the other half of the sheet 50 and that it is possible to proceed with the shearing of the two remaining comers, and to the punching of the second half of the sheet where required. At the end of the comer shearing and punching operations, as shown in Figure 9 the rotator causes a rotation of the sheet 50 by 90° and then it moves toward the panelling machine 1 in order to bring a first side of the sheet 50, to undergo bending inside the panelling machine 1. Once the first side of the sheet is bent, the manipulator moves back in order to extract the sheet from the panelling machine, therefore it rotates by 180° and it moves forward again, in order to bring a second side of the sheet 50, opposite to the first one inside the panelling machine, as shown in Figure 10. Once the second side of the sheet is bent, the manipulator moves back again in order to extract the sheet from the panelling machine, therefore it rotates by 90° and it moves forward again, in order to bring a third side of the sheet 50 inside the panelling machine, as shown in Figure 11. Therefore the operations are repeated, with a 180° rotation in order to bring a fourth and last side of the sheet 50 inside the panelling machine, as shown in Figure 12. Once the bending of the sides of the sheet is done, the manipulator-rotator carriage 3 moves back, the upper jaw 17 is lifted in order to release the finished metal sheet panel, that can be unloaded manually or preferably automatically. It is clear that the one just being described is only an example of a possible machining cycle of a metal sheet that can be carried out by the machine according to the invention.

Claims: Machine for machining metal sheets comprising a bending machine (1) with a workable (15) for bending sides of a metal sheet (50) and a manipulator-rotator (3) that is mobile in relation to the bending machine (1) for automatic positioning of the metal sheet (50) during bending, and further comprising at least one punching press (21, 30) for punching said metal sheet (50) characterised in that said at least one punching press (21,30) is served by said manipulator-rotator (3), and is arranged along the worktable (15) transversally to the direction of movement of the manipulator-rotator (3), said worktable (15) being divided in two parts, that are distanced so as to centrally define a rectilinear path (18) for the movement of the manipulator-rotator carriage, so that said manipulator-rotator (3) is utilised for automatic positioning of the metal sheet (50) both during bending and during punching of the metal sheet (50). Machine according to claim 1, characterised in that said at least one punching press (21, 30) is a mono-punch press. Machine according to claim 1, characterised in that said at least one punching press (21, 30) is a multi-punch press comprising a plurality of individually operable punching tools (26,29). Machine according to claim 1, characterised in that said at least one punching press (21, 30) comprises two punching presses, both served by said manipulator-rotator (3). Machine according to claim 4, characterised in that said two punching presses (21, 30) comprise a multi-punch press (21) and a mono-punch press (30). Machine according to claim 5, characterised in that said mono-punch press (30) is utilised for shearing the comers of the metal sheet (50). Machine according to claim 5, characterised in that said two punching presses (21, 30) each comprise at least a "C"-shaped supporting structure (25, 31) for punching tools that is transverse to a sliding direction of said manipulator-rotator (3) and with a throat facing toward said manipulator-rotator (3). Machine according to claim 7, characterised in that said at least one "C"-shape supporting structure (25, 31) is mobile transversally to the sliding direction of the manipulator-rotator, in order to position the punching tools in relation to the metal sheet (50). Machine according to claim 8, characterised in that said at least one "C"-shape supporting structure (25, 31) comprises two facing "C"-shaped supporting structures.

Inventors: VENTURINI GIANFRANCO, VENTURINI, GIANFRANCO
Applicants: SALVAGNINI ITALIA SPA, SALVAGNINI ITALIA S.P.A.
Application year: 1999
Main classification: B21D5
IPC codes: B21D43, B21D28, B21D5