Procedure for rapidly punching a blank from a metallic band

Abstract: A procedure for the rapid punching from a metallic band of a blank which is intended, particularly but not exclusively, for the manufacture of a detail of a furniture hinge, comprising the steps of: feeding a continuous metallic band (10) inside a punching group (17) comprising a matrix (21, 23) and a punch (26, 27), mobile in relation to each other to at least partially interpenetrate, punching, without swarf, of at least two blanks (11, 12) to be realised by said metallic band (10). The procedure is characterised in that said punching steps of said at least two blanks are carried out in a single station through a rapid succession of different punching steps on many horizontal planes along fixed and mobile outlines of matrices, supported by elastic elements which gradually give way.

Description: The present invention refers to a procedure for rapidly punching a blank, which is intended, particularly but not exclusively, for the manufacture of a detail of a furniture hinge, from a metallic band (see for example EP-A-0 672 478). The invention also refers to products obtained with said procedure. The large scale production of pieces, using a punching operation from a metallic band, always requires the resolution of the technical problem of material swarf, which should be kept to a bare minimum, of increasing productivity and of the reduction in costs, in order not to have too much of a negative effect on the cost of the finished product. Therefore, the possibility of realising a punched blank with the minimum possible swarf, particularly in the production of low-cost items, would be highly desirable. In order to obtain this result, different solutions have already been proposed which are all based upon the maximum use of the metallic band by searching for an ideal punching line, which is, however, also compatible with the actual manufacturing requirements. The systems which are generally adopted are those in which the punching of the blank is carried out according to a design such that on the metallic band the punched shapes fit together, and wherein the punching operation is carried out on the band which moves linearly or in zigzags. In this way the swarf is reduced to the bare minimum: nevertheless, some material must be left between one blank and the one next to it to be able to carry out the punching operation. In the most commonly used systems, the different steps of the punching operations are carried out in different punching stations. Such punching machinery has a relatively large size and has devices for the transportation of the pieces suitable for covering substantial distances. The high maintenance costs which result are directly dependant upon the number of punching stations, as well as the length and the complexity of the line of movement. Amongst the punching steps it is necessary to have a centring operation of the blank which is moved towards the next punching station. This step slows down the operation, represents a possible source of imprecisions in operation and acts, therefore, as a significant cost factor. The general purpose of the present invention is to overcome the drawbacks quoted above of the prior art in an extremely simple, cost-effective and particularly functional way. Given the aforementioned purposes, according to the present invention, we have put our minds to realising a procedure for punching a blank from a metallic band, such as to have practically no swarf of material thanks to the characteristics disclosed in the attached claim 1, and realised on moulding machinery, characterised in that it has a particularly compacted arrangement of its elements. The structural and functional characteristics of the present invention and its advantages compared to the prior art will become even clearer from an examination of the following description, referring to the attached schematised drawings, where: figures 1-4 show the steps of a procedure according to the invention; figure 5 schematically shows the punching lines of a first butting cut from a rectilinear band; figures 6 and 7 show some other examples of possible cutting sequences according to the procedure of the invention; figure 8 shows a frontal view of a punching group which can be used in a non-exclusive possible embodiment of the invention; figure 9 shows a side view of the punching group of figure 8. In figures 1-4, with 10 is indicated a suitably butted metallic band which, in an example of an embodiment according to the invention, is continuously fed to a punching station. Said band 10 is made to move forward step by step in the direction of the arrow F (figure 1), through any apparatus suitable for the purpose, which, being well known to men skilled in the art, is not illustrated in detail. According to the procedure of the invention at least two blanks, which fit together, are punched from the band 10 without any swarf, through a single multiple punching operation in the same cutting station. The blanks can have different forms depending upon the finished articles to be realised and can be the same as each other or different. Figure 2 shows, for example, two blanks which are the same as each other 11 and 12, punched according to a possible example of an embodiment of the present invention. A punching press moves one or more punches capable of interacting with the band 10 at different intervals. To such an end the punches (or the punch), for example with a different length, work together both with fixed matrices and with mobile matrices, supported by opposing elastic elements suitably capable of being calibrated in relation to the cutting forces being used. The punching operation is thus subdivided into many cutting steps in rapid succession, which separate the individual blanks, e.g. 11 and 12 according to the desired outlines, from the band. At the end of this single punching operation the band and the individual blanks are each situated on different horizontal planes. Advantageously, moreover, suitable clasping devices pick up the blanks and distribute them on further different horizontal planes, suitable for allowing the subsequent steps of moving the same blanks directly inside of the punching group, at any angle without interference, to be carried out (figure 2). According to an example of the procedure of the invention, the blank 12, outside of an axis of approach 13 of the pieces being processed, is positioned in parallel and suitably spaced from one another with respect to the blank 11, through a displacement which is carried out through means suitable for the purpose, which can be mechanical, pneumatic (figure 3), or even of another type. In the example schematised in figure 4, the two blanks 11 and 12, arranged aligned according to the axis 13 of approach of the pieces being processed, are then fed to the subsequent processing stations, such as a station where a drawing is realised. The subsequent work cycle starts with a new approach of the butted band 10 (figure 1). If the described punching operations should be a first cut of the butt from the rectilinear band 10' (figure 5), the punching procedure takes place in the same way as described for the butted band. The cut outlines will have the same length, but will produce the blank 11 and a swarf 12', equal to half a blank. The blank 11 will then be moved by the clasping elements and removed from the punching group in the same way as that which has already been illustrated, whereas the swarf 12' will be eliminated from the production cycle. By varying the arrangement in the plane of the punching group and the relative vertical movement of punches and matrices, but keeping the characteristic of punching at least two blanks in the same station with a single punching operation, it is possible to realise different execution sequences of the cutting lines during the different punching steps. The figures 6 and 7 show as an example two possible embodiments of the procedure which is the object of the present invention. In the solution schematised in figure 6, a flat formation 14 according to a first punching line 15a and 15b is separated from the continuous band 10. Such a flat formation 14 is, straight after, when the punches descend, divided along a second punching line 16 , creating two blanks 11 and 12. In figure 7 a different embodiment of the procedure which is object of the present invention is schematised, in which at each punching step the separation of an individual finished blank from the band 10 is obtained. In the example shown, where two blanks are present, the blank 11 is obtained through a first punching along the outlines 15a and 16 and thus the blank 12 punched along 15b. With reference to the description of the procedure made previously, the figures 8 and 9 show, as an example, a possible non-exclusive embodiment of a punching mould on which the punching procedure, object of the present invention, takes place in the particular case described in figure 6. Inside a punching group, wholly indicated with 17, the metallic band 10 is continuously fed along a guide 18 up to a stop device 19, integral with a fixed lower bearing structure 20, wherein a fixed matrix 21 is fitted. Inside a housing 22 of the bearing structure 20, is situated a mobile matrix 23, supported by opposing elastic elements 24, such as springs. The actuation of an upper mobile structure 25 brings two punches, a first punch 26 and a second punch 27, to act upon the band 10, interacting with the matrices 21 and 23 one after the other and thus determining the rapid succession of two punching steps. In the first lowering step the first punch 26, which in this embodiment mainly extends towards the bottom with respect to the punch 27, carries out the punching of the band development plane 14, from the continuous band 10, according to the first punching line 15a and 15b shown in figure 6. Such a line is generated by the fixed matrix 21 in the section 15b and by the mobile matrix 23 in the section 15a. In this step the matrices are integral with each other, since the mobile matrix 23 is fixed with respect to its housing 22, being supported by elastic opposing elements 24, which impart a holding force greater than the cutting force of the section 15a. The second punching step, immediately following the first, sees the second punch being engaged to cut the band development plane 14 along the second punching line 16 (figure 6). Indeed, in this second step the holding force imparted by the elastic opposing elements 24 on the mobile matrix 23 is overcome, allowing said matrix to slide in its housing 22. On the upper structure 25 clasping devices 28, such as magnetic, electromagnetic or suction rods are, moreover, foreseen, which act upon the band 10. Indeed, in the return movement of the mobile structure 25 the rods 28 then drag the blanks 11 and 12 up to interact with further clasping elements 29, such as magnets, electromagnets or suckers, which are present on the devices for picking up the individual blanks, which place such blanks on the aforementioned different horizontal planes. The pick-up devices consist, in this example, of a fixed bridge 30, which keeps the blank 11 in position, and of a trolley 31 which, in the discharge step of the blanks 11 and 12, moves the blank 12 laterally in the position opposing the blank 11 aligning it with the axis of subsequent processing 13. In the illustrated example the two blanks 11 and 12, positioned as in figure 3 in an upper horizontal plane with respect to the feeding position of the band 10 along the guide 18, are transferred along the axis 13 onto a station for a subsequent processing step through a rod transfer system of the known type. The advantage of the procedure which is the object here for punching a blank from a metallic band is mainly that of realising the two steps of punching the two blanks in quick succession in a single punching station of a punching press, which can thus be of a smaller size than that of currently known punching presses. Moreover, the fact that the initial development does not have to be repositioned in a second punching station substantially accelerates the punching frequency of the press and eliminates the risk of processing imprecisions caused by possible positioning errors. Consequently, the movement of the blanks can take place through shorter transfer rods. Such advantages also represent lower material and maintenance costs.

Claims: Procedure for the rapid punching from a metallic band of a blank which is intended, particularly but not exclusively, for the manufacture of a detail of a furniture hinge, comprising the steps of: feeding a continuous metallic band (10) into a punching group (17) comprising a matrix (21, 23) and a punch (26, 27), mobile in relation to each other to at least partially interpenetrate, punching, without swarf, of at least two blanks (11, 12) to be realised from said metallic band (10), characterised in that said punching steps of said at least two blanks are carried out in a single station through a rapid succession of different punching steps on many horizontal planes along fixed and mobile outlines of matrices, supported by elastic elements which gradually give way. Procedure according to claim 1, characterised in that in the first punching step there is a separation of a plane development (14) comprising at least two blanks (11, 12), which are separated following a second punching step. Procedure according to claim 1, characterised in that in each of said punching steps there is a separation of a single finished blank. Procedure according to claim 1, characterised in that at the end of said punching steps said at least one blank (12), defined outside of an approach axis (13) of the pieces being processed, is positioned on the axis, and suitably interspaced with respect to said other blank (11) which is aligned with said approach axis (13), through a movement which is carried out through actuation means (31). Procedure according to claim 1, characterised in that it uses at least two punches (26 and 27), actuated by the punching press of the punching group (17), of a different length. Procedure according to claim 5, characterised in that said at least two punches (26 and 27) are realised in a single piece, with punching planes at different heights. Procedure according to claim 5, characterised in that said at least two punches (26 and 27) are independent from each other. Procedure according to any one of the previous claims characterised in that said at least two blanks (11 and 12) are the same as each other.

Inventors: DONATIELLO GAETANO, DONATIELLO, GAETANO
Applicants: GI EMME S R L DI, DI.GI.EMME S.R.L.
Application year: 2001
Main classification: B21D28
IPC codes: B21D28