Single punching machine with fitting for mounting and centering tools

Abstract: Fitting for mounting and centering tools on a single punching machine comprising a turret-like head (4) which accommodates a hammer (5), a column (6) to which at least one horizontally rotating arm (7) is articulated, the arm (7) including a prism-like seat (8) in which the various punches (9) can be accommodated in each instance, means (16) being provided to actuate the arm from a position which does not interfere with the head (4) to a position which interferes therewith and is exactly vertically centered between the axes of the prism-like seat (8) and of the hammer (5); locking elements (15) being provided to lock the arm (7) in its active configuration.

Description: The present invention relates to a punching machine according to the preamble of claim 1. In order to produce holes with different cross-sections and profiles according to the requirements in the metal sheets being processed, punching machines manufactured so far can be fitted with templates which are interposed between the hammer of the machine and the metal sheet to be processed and allow to perforate said sheet for example with slots, holes with ellipsoidal cross-sections, and others. For each one of said profiles and for each one of said templates there is an equal number of punches, in practice one for each type of hole; although they operate excellently, they entail multiplying the expenditure in order to have a wide operating choice: furthermore, not all currently commercially available machines are compatible with the tools produced by the various manufacturers, and many times this forces the operators in the field to equip themselves with a plurality of punching machines in order to have the above mentioned operating range, with an increase in production and maintenance costs. Also known from DE-B-1 302 423 and FR-A-2 300 636 are punching machines as defined in the preamble of claim 1. There is the need to have machines which offer very high machining precision, in the range of a hundredth of a millimeter, and this characteristic is currently not available in all known punching machines, due both to problems in the wear and mechanical play of the moving parts and to actual design problems. The technical aim of the present invention is to provide a single punching machine with a fitting for mounting and centering known tools which allows to use the currently commercially available production of punches, regardless of the company which manufactures them, while maintaining the possibility of achieving higher part machining precision than currently obtainable. This aim is achieved by a punching machine as defined in the accompanying claims. Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of a fitting for mounting and centering known tools on a single punching machine, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a schematic top view of the present invention in a possible embodiment; figure 2 is a side view thereof. With particular reference to the above figures, the reference numeral 1 generally designates a fitting for mounting and centering known tools on a single punching machine, which is constituted by a base 2 for supporting metal sheets 3, above which a turret-like head 4 is operatively mounted. Said head is provided with a single hammer or tool means 5. Moreover, a vertical column 6 is laterally associated with the head, said vertical column 6 articulating an arm 7 which rotates in a horizontal plane along a circular path. The free end of the arm 7 is equipped with a prism-shaped seat 8 which is affected by a through seat 8a for accommodating punches 9 of a known type after interposing adapter elements which are not illustrated in the drawings. Elastic compression means 10 are provided between the hammer 5 and the prism-like seat 8, said compression means being arranged to automatically extract the punch 9 from the metal sheet 3 once punching has occurred; said elastic means 10 are constituted by at least one large helical spring 11 which is coiled around the punch 9, coaxially thereto, and is arranged to cooperate with a cap 12 in an upward position and with a circular collar 13 in a downward position and extract by contrast the punch 9 from the metal sheet 3 once punching has occurred; said collar is associated with the prism-like seat 8 with the interposition of a plurality of elastic compression springs 14. The active position of the arm 7 is kept stable by virtue of related elements 15 which consist of at least one hydraulically actuated cylinder 16 which is arranged horizontally on the punching machine and whose stem 16a extends tangentially to the lateral surface of the prism-like seat 8 until it enters a shaped recess 17 defined therein. Finally, the fact is stressed that the seat 18 for the accommodation of the hammer 5 and the recessed shape 19 of the die 2 are produced in a single boring step which makes them absolutely concentric. The operation of the invention can be deduced intuitively from the above description: in the non-interference position of the arm 7, shown in figure 1, the prism-like seat 8 is ready to receive a commonly commercially available punch, which is inserted in the through seat 8a after interposing an adapter element which is not illustrated in the drawings. Once the locking of the punch in the prism-like seat 8 is complete, the arm 7 is rotated until the axes of the hammer 5 and of said prism-like seat 8 are exactly centered vertically; in this configuration, the axis of the recessed shape 19 is also exactly centered with respect to the preceding ones, by virtue of the machining performed in order to define it, which entails, in a single machining step, the boring which generates the seat 18 for the snug-fit accommodation of the hammer 5 and the shape 19 itself. Once centering has occurred, the cylinder 16 is actuated, and its stem 16a, by protruding therefrom, engages the recess 17, keeping the arm 7 motionless during the punching step. Once the active step of said punching step, which entails the compression of the large spring 11, has ended, the spontaneous expansion of said spring facilitates the extraction of the punch 9 from the metal sheet 3; the stem 16a is retracted and the arm 7 can, if required, be rotated again into the configuration in which it does not interfere with the hammer 5. Subsequently the punch 9 can be replaced in the prism-like seat 8 with another one which has a different cross-section and is in any case of a known type. In practice it has been observed that the invention thus described achieves the intended aim. The invention thus conceived is susceptible to modifications and variations, all of which are within the scope of the inventive concept as defined by the claims; thus for example, the hydraulically actuated cylinder 16 can be replaced with a rotating pawl whose hook can be precisely inserted in the recess 17. Furthermore, all the details may be replaced with other technically equivalent elements. In the practical execution of the invention, the materials employed, as well as the dimensions, may be any according to the requirements without thereby abandoning the protective scope of the following claims. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: A punching machine comprising a base (2) for supporting metal sheets (3), a turret-like head (4) operatively mounted above said base (3) and provided with hammer means (5), a vertical column (6) provided laterally to said hammer means (5) and connected to said head (4), a horizontal arm (7) articulated to said vertical column (6) and rotatable with respect to said head (4) and said hammer means (5) in a horizontal plane, said horizontal arm having a free end provided with at least one prism-like seat (8) defining a snug-fit through seat (8a) for accommodating a punch (9), said arm (7) being rotatable from an inoperative position, whereat said seat (8) and said punch (9) are located remote from and do not cooperate with said hammer means (5), to an operative position whereat said seat (8) and said punch (9) accommodated therein are vertically centered and located in coaxial alignment with the axis of said hammer means (5), elastic compression means (11) being provided between said hammer means (5) and said prism-like seat (8) for automatically extracting said punch (9) from a metal sheet (3) upon completion of a punching operation, wherein it further comprises locking means (15, 16, 16a) connected to said punching machine and including a movable locking member (16a), and a recess (17) shaped correspondingly with respect to said movable locking member (16a), said movable locking member (16a) being engageable in said recess (17) upon locating said horizontal arm (7) in said operative position for maintaining axial alignment of said seat (8), said punch (9) and said hammer means (5), characterized in that the locking member (16a) is movable in a horizontal direction and the recess (17) is defined on a perimetric face of said seat (8). A punching machine according to claim 1, characterized in that said locking means (15) comprise at least one hydraulically actuated cylinder (16) rigidly supported by said punching machine and having a horizontal axis, and in that said movable locking member (16a) comprises a stem (16a) of said hydraulically actuated cylinder (16), said stem (16a) being orientated tangentially with respect to an outer perimeter of the prism-like seat (8) upon locating said arm in said operative position and having a free end insertable in said recess (17), said recess (17) being shaped correspondingly with respect to said free end of said stem (16a). Machine according to claim 1, characterized in that said locking means (15) comprise a rotatable pawl, and wherein said movable locking member comprises a hook supported by said rotatable pawl, said recess (17) being shaped correspondingly with respect to said hook.

Inventors: LENZOTTI EUGENIO, LENZOTTI, EUGENIO
Applicants: LENZOTTI EUGENIO, LENZOTTI, EUGENIO
Application year: 1992
Main classification: B21D37
IPC codes: B21D28, B21D37