A device for moving the blades of a press used for bending sheets

Abstract: A device for moving blades of a press used for bending sheets, has blades supported and placed in motion by a cutter block which is movable in the vertical direction with respect to two counter blades with the sheet to be bent being placed between the two counter blades. For the purpose of imparting motion to the cutter block with respect to the counter blades, there is provided a track along which the cutter block rolls. There are also provided two connecting rods, the upper end of which is hinged to the lower part of the cutter block. The two rods are pivoted in the lower part to an arm (7) which is placed substantially radially and which is integral with a cylinder (8). Cylinder (8) is integral with a second arm (9) which is connected with another cylinder. There may also be provided a third cylinder which forms with the second cylinder a structure having cylindrical symmetry.

Description: The present invention relates to a device for moving the blades in a press for bending sheets. Bending presses for sheets which are used for the production of panels which are bent in the portions corresponding to their borders on at least one of their sides have been known for some time. In particular, bending presses are known in which blades supported and placed in motion by a suitable support block the block being mobile in the vertical direction with respect to two counter blades between which the sheet to be bent is placed. This type of device is described in EP-A-0298056 filed in the name of the same inventor. According to this device, the support block is shaped essentially as a "C" and is placed in motion by at least one fluid cylinder, the position of which may be predetermined by acting on a shaft disposed longitudinally along the entire length of the device. Around this shaft there is placed an eccentric element placed in a suitable seat formed on the lower extension of the cylinder. In actual practice, the angular position of this shaft is capable of determining the position of the cylinder and therefore is capable of predetermining the bending angle assumed by the sheet after the fluid cylinder performs its function. This device as well as other similar devices of well known type present the serious problem residing in the difficulty of always maintaining the support block perfectly parallel with respect to the working plane because if this is not achieved, the bendings obtained are of unacceptable quality. For the purpose of solving this problem, there has been proposed to use a complex and delicate fluid assembly which presents substantial complications with consequent problems both from the constructive as well as the functional point of view. These difficulties become more serious due to the fact that the hydraulic fluids being used operate under conditions of high pressure from 100 bars and higher, and they exhibit a serious decrease in volume, particularly in the case of bendings which are performed asymmetrically with respect to the longitudinal center line of the group of bendings. Alternately, it has been possible to use a complex device which uses a torsion shaft with pinions and racks. An object of the present invention is to provide a device for moving the blades of bending presses for sheets of the type described hereinabove and which is simpler from the constructive point of view and more reliable from the functional point of view when compared with similar devices of a known type. The object of the invention is solved by a press with the features of the independent claim 1. According to the invention, further, there is provided that a second radial arm is integral with the cylinder and to the external extremity of this second arm there is pivoted the extremity of a piston rod of a fluid cylinder pivoted to the fixed frame of the apparatus. These above and further features of the invention will be described hereinbelow in detail by reference to a particular embodiment by way of a non-limiting example by reference to the accompanying drawings of which: Fig. 1 is a schematic side view of the device of the invention. Fig. 2 illustrates a transversal view in cross section according to lines II-II in Fig. 1. Figs. 3-6 illustrate the sequence of the phases of operation according to the invention. As shown in Fig. 1, the press is of the type in which blades (1) are supported and placed in motion by support block (2) which is mobile in the vertical direction with respect to two counter blades (3) between which the sheet to be bent is placed. In the rear part, the cutter block is provided with rolls (4) capable of rolling along track (5) of an appropriate shape. The main feature of the device of the invention consists of the fact that the upper end of at least two connecting rods (6) is pivoted to the lower part of the cutter block. The two connecting rods are in turn pivoted in their lower part to an arm (7) as shown also in Fig. 2 which is integral and which is disposed in a position substantially radial on shaft (8), the latter being disposed with an axis which is parallel to the working plane. Fig. 2 also shows that advantageously each one of the two connecting rods is placed in a position corresponding to one end of shaft (8). A further radial arm (9) is integral with shaft (8). To the end of the arm (9) there is pivoted the end of piston rod (10) of fluid cylinder (11) which in turn is pivoted to the fixed frame of the apparatus. Advantageously on top of cylinder (11) and integral with respect to the latter, there is placed another fluid cylinder (13) which forms with cylinder (11) a single structure (15) having cylindrical symmetry. The second cylinder (13) has a piston rod (14) which is coaxial with respect to the first piston rod (10). The two piston rods exit from the opposite surfaces of the structure (15). In particular, the extremity of piston rod (14) placed coaxially with respect to cylinder (13) is pivoted in point (12) to the fixed frame of the apparatus. The motions of the support block (2), for the purpose of obtaining effectively the bending action, are made dependent to the corresponding motion of the piston rod (14) in the interior of the corresponding fluid cylinder (13). In the case in which there is used only cylinder (11) with the only piston rod (10), it is evident that the motions of the support block (2) depend only on the motion of piston rod (10). It is clear that in this manner the device is more economical but it is inherently slower with respect to the device which includes two coupling cylinders. The device according to the invention is superior with respect to similar devices of known type because it guarantees the parallelism of the support block with respect to the working plane. Further, with the known hydraulic devices, it is necessary to restore the parallelism of the support block in the loading phase of every new panel with consequences of substantial complications. In the devices which have pinions and racks, there is no parallelism and this involves substantial wear of the teeth of the rack. Finally, the device according to the invention permits to use one or two cylinders instead of a plurality of cylinders, at least five, which are used in known devices with substantial saving from an economical point of view. Finally, the device according to the invention guarantees absolute uniformity in the bending of the sheet.

Claims: A press for bending the edges of sheets, the press comprising a fixed frame, two counter blades (3) in between of which a sheet to be bent can be clamped in a substantially horizontal working plane, a support block (2) with blades (1) mounted thereon, the support block (2) being movable in the vertical direction relative to the counter blades (3) in such manner that in use, the edge of the sheet is bent, characterised in that the support block (2) is movable by means of two parallel connecting rods (6) lying in a plane substantially perpendicular to the working plane and parallel to the edges of the blades (1), the upper part of each connecting rod (6) being hinged to the lower part of the support block (2), the lower part of each connecting rod (6) being pivotally connected to a first arm (7) integral with a rotatably mounted shaft (8), the axis of the shaft (8) being parallel to the working plane and the first arm (7) extending substantially radially from the shaft (8) in a direction substantially parallel to the working plane, the shaft (8) having a second radial arm (9) integral therewith, the press further comprising a fluid cylinder (11) having a piston rod (10), the end of which is pivotally connected to the outer end of the second arm (9), the fluid cylinder being hinged on the fixed frame. A press according to cliam 1, characterised in that one first arm (7) is disposed on one longitudinal end of said shaft (8), the other first arm (7) being disposed on the opposite longitudinal end of the shaft (8). A press according to claim 1, characterized in that a second fluid cylinder (13) is interposed between the first fluid cylinder (11) and the fixed frame, the first and second cylinder being integral, the second fluid cylinder (13) having a second piston rod (14) which extends coaxially with, and in a direction opposite to, the first piston rod (10), the external end of the second piston rod (14) being hinged to the fixed frame.

Inventors: CODATTO ANTONIO, CODATTO, ANTONIO
Applicants: SAPIM AMADA SPA, SAPIM AMADA S.P.A.
Application year: 1993
Main classification: B21D5
IPC codes: B30B1, B30B15, B21D5