Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
  • B21D5/02—Bending sheet metal along straight lines, e.g. to form simple curves on press brakes without making use of clamping means
  • B21D5/0209—Tools therefor

Definitions

• the present invention relates to a device for fixing a tool to the cursor of a bending- press.
• bending-presses are provided with tools (punches) for bending, for example, sheet by pressing it within corresponding fixed bottom dies. For each sheet process there corresponds a special tool, which must be changed each time.
• Bending-presses are provided with a cursor, that is, a moving member controlled for carrying out the bending operation, also called tool-holding board, intermediate or piston, and with at least one device that allows fixing the bending tool to the cursor.
• a cursor that is, a moving member controlled for carrying out the bending operation, also called tool-holding board, intermediate or piston, and with at least one device that allows fixing the bending tool to the cursor.
• the device serves for removably fixing the tool to the cursor, for allowing the operators to replace it quickly.
• the device comprises a central body and a tightening bracket that form a vice structure.
• the bracket directly screws onto the body for locking a tang of the tool in abutment thereon.
• the major problem of these systems is that in order to replace the tool it is necessary to extract the tang from the vice laterally, sliding it, a particularly delicate and difficult operation for which a free side space is also required.
• an electrical, hydraulic or pneumatic control is used in place of the manual screw-locking.
• the main object of the present invention is to improve this prior art.
• a further object is to allow aligning the punch on the device without having to resort to squashing or to initial bending tests, which extend the production time and increase scrap.
• the particular trajectory followed by the tightening element offers several advantages.
• the tightening element moves away from the central body and leaves the necessary space to easily removing the punch, while when the punch must be locked, the tightening element not only presses it against the central body but also lifts/pulls it to perfectly abut it against the abutment. Easy removal and locking accuracy are obtained at the same time.
• the means for moving are adapted for moving the tightening element along a circumference arc, keeping it parallel to the surface of the central body.
• the means for moving comprise reciprocal articulation means between the tightening element and the central body adapted for imposing the above composite movement.
• the articulation means may comprise:
• two stiff articulation elements for example plates, mounted at the sides of the tightening element and having each two hinging points to the central body and two hinging points to the tightening element, for forming an articulated parallelogram structure;
• stiff articulation element for example substantially C- or bridge- or arch-shaped, comprising a central portion and two portions orthogonal thereto, wherein the two portions have each, at the end, a hinging point to the central body and in the proximity of the central portion, a hinging point to the tightening element.
• the axes passing through the hinging points on the tightening element and the central body are parallel.
• the stiff articulation element may be mounted astride of the tightening element or between this and the central body.
• the solution with a stiff articulation element is advantageous because a single element allows obtaining the desired movement stiffly guiding the tightening element.
• the tightening element is mounted for slightly oscillating about the hinging axis relative to the stiff articulation element.
• the central body comprises a groove wherein a projection or tooth of the tightening element may insert in the first position only, thus allowing a rotation of the tightening element about the hinging axis. In this way it is possible to further separate the tightening element from the central body and facilitate the tool removal more.
• the grove and tooth position may also be exchanged.
• the device comprises means for imparting a force to the tightening element for moving it between, and locking it at, the first and second position.
• Such imparting means may comprise a closing element manually screwable into the central body and in engagement on the tightening element, so that by screwing the closing element it pushes the tightening element towards the central body and at the same time it acts as stopping and/or travel-end element adapted for defining (the extremes of) the first and second position.
• a closing element manually screwable into the central body and in engagement on the tightening element, so that by screwing the closing element it pushes the tightening element towards the central body and at the same time it acts as stopping and/or travel-end element adapted for defining (the extremes of) the first and second position.
• a threaded element with very long pitch would be required, but for example a very large (cumbersome) and easily reversible (poor safety) screw should be mounted.
• the invention solves the problem with a composite closing element, having a turnable head in sight engaged in a slit of the tightening element and a body that goes through the tightening element up to the central body, where it ends connecting integrally to a large-pitch threaded element (screwable in the central body).
• a pitch 3 is used, equal to a metric M24 on the diameter. In any case, it is preferred that this pitch is such as to allow the passage from the first to the second position with at most half screwing turn of the turnable head.
• the tightening element comprises a longitudinal stopping tooth, which couples to a corresponding groove into the tool and serves for both preventing the accidental drop thereof and for pulling it towards the abutment of the central body.
• a longitudinal stopping tooth which couples to a corresponding groove into the tool and serves for both preventing the accidental drop thereof and for pulling it towards the abutment of the central body.
• such tooth is mounted on elastic means, in order to allow a slight bending thereof useful during the assembly/removal phase for favouring the insertion and the removal of the punch.
• the longitudinal tooth is divided into a plurality of minor aligned teeth, each mounted on an independent spring.
• the spring may be made as a harmonic steel spring divided into as many bending portions as are the teeth of the above plurality. It is preferred to use two equal overlapped springs for improving the elastic return and response.
• the tightening element is not flat but slightly arched so as to space apart more from the central body.
• the screwable element is preferably engaged at the centre thereof.
• the slightly arched shape compensates the deformation generated by the punctual application of the tightening force only at the centre thereof (through the closing element).
• FIG. 1 shows a front view of the device of the invention
• - figure 2 shows a cutaway view according to plane II-II;
• - figure 3 shows a three-dimensional top view of the device in fig. 1 ;
• FIG. 5 shows a plan view of a leaf spring
• - figure 6 shows a three-dimensional view of a component of the device in fig. 1 ; - figures 7 and 8 show a three-dimensional view of some internal parts of the device in fig. 1.
• the hinging is obtained through pins 40, 42, which hinge the wings 34, 36 respectively to the central body 20 and to the sides of element 24.
• the overall result is that the articulation element 30 is mounted oscillating on the central body 20 about an axis XI, whereas the tightening element 24 is mounted (slightly) oscillating about an axis X2, parallel to XI.
• a screwing element 50 (see also fig. 7 and 8) composed of a head 52, exposed outwards for manual screwing, a partially hollow longitudinal body 54 that extends up to the underlying central body 20, and a threaded bushing or portion 56 integrally fixed to body 54 by a screw 58.
• Bushing 56 has a sufficiently long pitch as to ensure that - as shall be better explained hereinafter - the tool locking movement requires only a fraction of round angle on the screwing element 50.
• head 52 moves close or away to/from the central body 20 along an axis Y orthogonal to the central body 20.
• the top edge of the tightening element 24 comprises a projection or tooth 60 facing the central body 20, which in turn exhibits a groove or concavity 62 wherein such tooth 60 may enter subsequent to an oscillation of the tightening element 24 about axis X2.
• the bottom edge of groove 62 also has a chamfer 64 for the resting of tooth 60.
• Tooth 70 consists of an aligned series of secondary teeth 72 that are fixed to a leaf spring 74 made of harmonic steel.
• Spring 74 (see fig. 5) is divided into flexible lips 76, on each one there being mounted a minor tooth 72.
• spring 74 is actually given by the overlapping of two equal springs, for improving the elastic resistance and limiting the deformations.
• Device 10 operates as follows. With the screwing element 50 at the maximum distance away from the central body 20, the tightening element 24 is at the maximum distance away from the central body 20 along axis Y. It is then possible to insert the tool between the tightening element 24 and the flat portion 28. The tool pushes the tightening element 24 upwards, so that tooth 60 sets over groove 62 and, if forced, enters therein. This means that the tightening element 24 may slightly tilt relative to the central body 20, rotating about axis X2 for (slightly) enlarging the entrance of the vice structure and facilitating the mounting of the punch.
• the tightening element 24 not only presses the tool against surface 28 but with tooth 70 it pulls the tool towards the flat stopping surface 26.
• the composite movement therefore ensures a perfect contact on surfaces 26, 28, which also leads to high processing accuracy.
• spring 74 may bend in some of its component teeth 72 in the case of different tolerances in the punch profile that abuts against the stop surface 26. Besides improving the press adaptability to any punch, this solution improves the processing accuracy compensating the mechanical tolerances in the punch.
• the articulation element 30 allows the dual and concurrent movement described above to the tightening element 24 (movement on a circumference arc having as a radius the distance between axes XI and X2), and with its stiffness it ensures the constant parallelism between axes XI and X2.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Bending Of Plates, Rods, And Pipes (AREA)

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• 2010
  • 2010-05-13 WO PCT/IB2010/052132 patent/WO2011141774A1/en active Application Filing
  • 2010-05-13 EP EP10724140A patent/EP2569107A1/de not_active Withdrawn

Non-Patent Citations (1)

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