Abstract:
The present invention relates to a device comprising rotary cutting tools for combining cutting and shaping operations on metal sheets, the density of the cuts preferably being very high, said cutting operations preferably being integrated into an automated shaping line, characterised in that it comprises a first pair of rotary cutting tools ( 1, 2 ) producing a first set of cuts ( 7, 7′, 7″ ) and a second pair of rotary cutting tools ( 3, 4 ) completing and finishing off the first cuts by a second set of cuts or by a fold ( 8 ) in order to obtain a final closed cut with the drop of cut waste or a puncture, respectively

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a new method for combining industrial operations of cutting and shaping, preferably in line.  
           [0002]    The invention also relates to rotary tools allowing to implement the method.  
         STATED OF THE ART  
         [0003]    The combination of cutting and shaping operations is known in many industrial applications. These cuts may be few or, on the contrary, the density of cuts may be very high. It is the case for instance with acoustic shaped products or shaped products intended to act as cable conduits.  
           [0004]    One of the techniques for producing partitions with acoustic sound-absorbing properties is based on the use of shaped metal facings with a surface having numerous holes. The current methods consist in using either perforated shaped products, generally with round holes of small diameter, or otherwise shaped products in which punctures have been produced. The punctures are partial cuts leaving the cut waste attached to the metal sheet, these cuts generally being rectangular. The above-mentioned shaped products are characterised by a very high density of cuts, of the order of several thousand holes per square metre.  
           [0005]    Shaping ranks among the most-used techniques allowing to produce cable conduits. In this case, the operations of cutting and shaping also have to be combined. The number of cuts, lower than in the case of acoustic shaped products, still remains very high.  
           [0006]    Other products, such as uprights for metal shelves, are commonly produced from shaped products with cuts. In this last example, the cuts are in any case far less numerous.  
           [0007]    To obtain these shaped products with more or less numerous cuts, different methods are used. In fact, two major groups of methods must be distinguished depending on whether the cuts are produced by means of a press or by means of rotary tools.  
           [0008]    The cuts produced with a press may be produced before the shaping operation, off the shaping line, or by a press installed within the shaping line or even after the shaping operation.  
           [0009]    When the cuts are produced before and off the shaping line, additional handling stages are numerous and entail considerable additional cost. When the press is placed within the shaping line, the cutting operation significantly slows down the shaping speed. Finally, producing cuts after shaping creates limitations as regards the position of the cuts on the shaped product because of the access restrictions imposed by the cutting tool, which also adversely affects the productivity.  
           [0010]    Rotary tools offer an interesting alternative to the use of presses in the sense that they can operate at speeds that are compatible with that of the shaping line.  
           [0011]    Such types of tools are for instance described in the patents (patent applications) GB-A-1 044 313, GB-A-1 123 536, U.S. Pat. No. 1,581,236, U.S. Pat. No. 1,333,704, U.S. Pat. No. 3,828,636, U.S. Pat. No. 3,205,744, U.S. Pat. No. 3,709,077, U.S. Pat. No. 3,438,835, U.S. Pat. No. 3,274,873, U.S. Pat. No. 3,066,542 and U.S. Pat. No. 5,040,397. The systems described in these various documents do not provide a suitable solution to the problems herein considered. Either they are only intended for cutting operations and not for perforation, or implementing them is very complicated and expensive when many perforations have to be produced. In particular, their problem is the discharge of very large amounts of waste resulting from the perforation.  
           [0012]    An alternative thus implemented in this case is puncture, which consists in producing a partial cut, leaving the waste attached to the metal sheet, which eliminates the problem of its discharge. This operation may be performed by rotary tools but then it has other drawbacks. The lower knives being disks, a quality cut is only achieved in the direction that is parallel to the movement of the metal sheet, the perpendicular side being rather torn, which may reduce the resistance to rust. Moreover, with the waste remaining attached to the metal sheet, it prevents the production of punctures in areas in contact with shaping rollers, which significantly reduces the relative surface of the shaped product in which punctures may actually be produced. In addition, due to the rotary tool technology, the angle of the waste relative to the plane of the metal sheet is closer to 45° than to 90°, which significantly reduces the visible aperture. The acoustic shaped products produced with the puncture technique thus present significantly worse performances than those produced by drilling.  
           [0013]    The American patent U.S. Pat. No. 4,766,707 describes a machine comprising a first pair of rotary drums for drilling followed by a second pair of rotary drums for cutting a metal strip. According to the proposed installation, this machine is followed by a forming or folding machine with a view to producing clips intended for roofing panels. The first pair of tools produces a conical embossing or a hole which subsequently serves to receive a fixation means, such as nails. The second pair of tools produces a transverse groove on each longitudinal edge of the strip, two adjacent sections of strip now being only loosely connected in the middle, with a view to favor the subsequent easy separation of the clips. The speeds of both types of operations are significantly different.  
           [0014]    The American patent U.S. Pat. No. 1,931,468 describes a similar installation in which the movement of the pairs of rollers is coordinated by a system of gear drive. Drilling in one or two operations is achieved by means of a pair of rotary tools, one of which having channels for the discharge of cut waste.  
         AIMS OF THE INVENTION  
         [0015]    The present invention aims to provide a solution allowing to overcome the drawbacks of the state of the art.  
           [0016]    In particular, the present invention aims to propose a rotary tool technology allowing either to cut numerous small-sized holes on the shaping line, or to produce punctures with improved geometry without adversely affecting the shaping speed.  
         MAIN CHARACTERISTIC ELEMENTS OF THE INVENTION  
         [0017]    The present invention relates to a device comprising rotary cutting tools for combining cutting and shaping operations on metal sheets, the density of cuts preferably being very high, said cutting operations preferably being integrated into an automated shaping line, characterised in that it comprises a first pair of rotary cutting tools producing a first set of cuts and a second pair of rotary cutting tools completing and finishing off the first cuts by a second set of cuts or by folding in order to obtain a final closed cut with the drop of cut waste or a puncture, respectively.  
           [0018]    According to a first preferred embodiment of the invention, with the final cut being essentially rectangular, the first pair of rotary tools cuts in the transverse direction relative to the travel direction of the metal sheet in order to produce notches and the second pair of rotary tools cuts in the longitudinal direction relative to the travel direction of the metal sheet. It should be noted that the roles of both pairs of tools may be reversed (first cut in the longitudinal direction, then in the transverse direction).  
           [0019]    According to a second preferred embodiment of the invention, with the final cut being essentially rectangular and of the puncture type, said first pair of tools cuts on three adjacent sides of said rectangle and said second pair of tools makes a fold relative to the axis formed by the fourth side of said rectangle.  
           [0020]    Preferably, said rotary tools are mounted on shafts supported by bearings, the axes of which are perpendicular to the travel direction of the metal sheet.  
           [0021]    Advantageously, the rotation direction of the upper and lower tools is such that the tangential speed of said tools at the point of contact with the metal sheet is in the same direction and essentially of the same magnitude as the speed at which the metal sheet passes.  
           [0022]    As a particular advantage, said device comprises a means for ensuring the relative positioning depending on the circumference of the teeth of the upper and lower tools of said first pair of circular tools, said means preferably being a gearbox that takes up the play in order to synchronise the shafts.  
           [0023]    According to a particular embodiment of the device of the invention, the first pair of tools comprises an upper tool comprising an alternating series of simple circular knives and of spacers and a lower tool comprising an alternating series of simple circular knives and elements acting as lateral knives. In addition, the second pair of tools comprises an upper tool and a lower tool, each comprises an alternating series of simple circular knives and of spacers.  
           [0024]    Advantageously, each upper simple, circular knife comprises teeth on its periphery, the arc of which having a length that is equivalent, apart from the sets of cuts, to the distance between the two notches associated with the same final cut and produced by the first pair of tools. The simple, circular knives, together with the spacers of the second pair of tools, have widths that are essentially equivalent apart from the sets of cuts.  
           [0025]    The device of the invention is advantageously provided with a means for favoring the discharge of the cut waste, preferably combs, the teeth of which fit between the simple, circular knives of the second pair of tools.  
           [0026]    Still according to the invention, the upper tool of the second pair of tools may be provided with teeth which are rounded or smoothed at the level of the fold line and have sets that are compatible with the fold.  
           [0027]    Another aspect of the present invention relates to a method for combining operations of drill-type cutting and shaping of metal sheets, the density of the cuts preferably being very high, said cutting operations preferably being integrated within an automated shaping line, characterised by the following successive stages:  
           [0028]    a first pair of rotary cutting tools produces a first set of transverse cuts relative to the travel direction of the metal sheet;  
           [0029]    a second pair of rotary cutting tools produces a second set of longitudinal cuts relative to the travel direction of the metal sheet, the combined result of both operations being a set of closed cuts, preferably rectangular;  
           [0030]    the cut waste is discharged by the movement of the tools, preferably by means of combs that are incorporated into the second pair of tools and/or transversally discharged by a transport belt.  
           [0031]    The invention also relates to a method for combining puncturing and shaping operations on metal sheets, said cutting operations preferably being integrated into an automated shaping line, characterised by the following successive stages:  
           [0032]    a first pair of rotary cutting tools produces a first set of U-shaped cuts forming a rectangle;  
           [0033]    a second pair of rotary cutting tools produces a fold, the axis of which intended on the remaining side for forming a set of rectangular cuts of the puncture type;  
           [0034]    As a particular advantage, the method of the invention can combine, on a same machine, cutting and puncturing operations distributed along metal sheet strips that are parallel to the travel direction of the metal sheet, said punctures being produced in areas that do not come into contact with the shaping tools.  
           [0035]    Advantageously, said rectangular drilled or punctured cuts are shifted, the shift between two adjacent cuts being equal to the longitudinal pitch (Plg) divided by a shift parameter X, X being non-zero.  
           [0036]    In actual use, the device of the invention is used in order to produce partitions the acoustic sound-absorbing properties, to produce cable conduits or even to produce metal shelves.  
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0037]    [0037]FIG. 1 shows an overview of the rotary tool system according to the present invention.  
         [0038]    [0038]FIG. 2 shows two tool elements belonging to the first pair of rotary tools corresponding to FIG. 1.  
         [0039]    [0039]FIG. 3 shows an elevated view of the first pair of rotary tools according to the invention.  
         [0040]    [0040]FIG. 4 shows two particular embodiments of the teeth of the upper rotary tool shown in FIG. 3.  
         [0041]    [0041]FIG. 5 shows the detail of the notches produced with the first pair of tools according to one preferred embodiment of the invention.  
         [0042]    [0042]FIG. 6 shows a detailed view of both tool elements belonging to the second pair of corresponding rotary tools of FIG. 1.  
         [0043]    [0043]FIG. 7 shows an elevated view of the second pair of rotary tools according to the invention.  
         [0044]    [0044]FIG. 8 shows an optimised positioning diagram for the cuts in the metal sheet, according to the invention.  
         [0045]    [0045]FIG. 9 shows the parameters allowing to define the cuts like those shown in FIG. 8.  
         [0046]    [0046]FIG. 10 shows a real example of a cutting diagram according to the invention.  
         [0047]    [0047]FIG. 11 shows the detail of the cuts produced with the first pair of tools according to a second preferred embodiment of the invention, alternately in the longitudinal and transverse directions, respectively.  
         [0048]    [0048]FIG. 12 shows the detail of the teeth of the simple folding tool on the second pair of tools corresponding to the cuts in FIG. 11.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0049]    The present invention aims to obtain either a rectangular cut or a puncture by splitting the operations into two phases so as to ensure a good quality of cut and easy discharge of the waste in the case of the cut or a good quality of cut and fold in the case of the puncture.  
         [0050]    The basic principle, shown in FIG. 1, consists in using two successive pairs of rotary tools. In the case of hole-cutting, this principle allows to split the cutting operation into two phases. On the one hand, the first pair of rotary knives produces transverse cuts relative to the travel direction of the metal sheet. On the other hand, the second pair produces longitudinal cuts and ensures easy discharge of the waste. In the case of puncture-type cuts, the first pair of knives produces, for instance, cuts on three sides. The second pair then folds back the cut waste, which allows to obtain a significantly improved visible aperture compared with the state of the art. Moreover, in the closely related state of the art U.S. Pat. No. 4,766,707, the successive operations performed by the rotary tools (embossing or drilling, shearing) are carried out on different areas and are used for completely different purposes.  
         [0051]    [0051]FIG. 1 shows an overview of the system. A first pair of rotary tools comprising tools  1  and  2 , mounted on shafts  6  and  6 ′ respectively, produces a partial cut in the metal sheet without discharging the waste. The cut is finished off by a second pair of tools comprising tools  3  and  4 , mounted on shafts  6 ″ and  6 ′″ respectively. These shafts are supported by bearings mounted in heads that are similar to the shaping heads (not shown). The rotation direction of each tool is indicated (B, B′, B″, B′″). The metal sheet travels in the direction A, in the direction indicated, and is equivalent to the peripherical speed that is shared by tools 1, 2, 3 and 4.  
       DESCRIPTION OF SEVERAL PREFERRED EMBODIMENTS OF THE INVENTION  
       [0052]    [0052]FIGS. 2 and 3 show a preferred embodiment of the rotary tools  1  and  2 . In particular, FIG. 2 shows the upper  11  and lower  21  circular tool elements which produce a notch  7  perpendicular to the travel direction of the metal sheet  5  (see FIG. 5). As shown in FIG. 3, the upper tool  1  comprises a stack of simple circular tools  11  and of spacers  12 . These tool elements are mounted on the shaft  6 , positioned and fixed onto the shaft in the rotation direction by elements such as pins. These elements are also fixed in the axial direction so as to ensure precise positioning. The lower tool  2  similarly comprises a stack of elements  21 , facing the elements  11  and separated by elements  22  serving as lateral knives when cutting the notch  7 . The elements  21  and  22  are fixed in rotation and are positioned in the axial direction, as is the case for tool  1 . The elements  11 ,  21  and  22  are preferably made of a thermally-treated tool steel, as is the case for standard cutting tools.  
         [0053]    This construction method of the rotary tools is especially advantageous since it allows the economic manufacture of the tools, as the elements such as  11  or  21  may be produced by wire cutting a stack of disks made of treated tool steel.  
         [0054]    The positioning in the axial direction of the tools  1  and  2  is ensured by stops mounted on the shafts at the level of the bearings located in the support head. The relative radial positioning of the teeth of the circular tools  11  and  21  is ensured by at least one gearbox which synchronises the shafts  6  and  6 ′. These are preferably gears that take up the play so as to ensure the precise positioning that is compatible with the sets of cuts. At least one of the shafts  6  or  6 ′ is motor-driven so as to guarantee a circumpherential rotation speed of the tools that is equal to the travel speed of the metal sheet A.  
         [0055]    [0055]FIG. 4 shows two embodiments of the teeth  111  or  111 ′ of the circular tool  11 .  
         [0056]    After passing through the first pair of rotary tool, the metal sheet has notches  7  as shown in FIG. 5.  
         [0057]    [0057]FIGS. 6 and 7 show the simple knives  31  and  41  performing the second cutting operation. The circular knife  31  has teeth  311  on its periphery, the arc of which has a length that is equivalent, apart from the sets of cuts, to the distance between two successive notches  7 . The complete upper circular tool  3  comprises a stack of simple knives  31  separated by spacers  32 . The axial and circumpherential positioning of the knives  31  is similarly ensured as that of tools  1  and  2 . In addition, the shaft  6 ″ is synchronised relative to the shaft  6  so as to ensure the precise positioning of the notches  7  relative to the knives  311 . This synchronisation is for instance achieved by a system of gears.  
         [0058]    The tool  4  comprises a stack of simple cutting disks  41  and spacers  42  (FIG. 7). Their axial positioning is ensured as for the tools  1  and  2 , the relative positioning of the tools  3  and  4  must only be guaranteed in the axial direction. The elements of tools  11 ,  21  and  31  and the spacers  42  have widths that are equivalent, apart from the sets of cuts.  
         [0059]    The cut waste is very easily discharged between the disks  41 , a comb, the teeth of which fit between the disks  41 , may possibly be provided in order to ensure the discharge of waste which would be stuck between the cutting disks  41 , the waste then being transversally discharged, for example by means of a transport belt.  
         [0060]    [0060]FIG. 8 diagrammatically shows an optimised positioning of cut. Indeed, a delicate stage of the method is delivering the right amount of cutting force ut, particularly when cutting the notches with tools  1  and  2 . In order to reduce this force, it may therefore be worthwhile to shift the cuts as shown in FIG. 8.  
         [0061]    The parameters to be considered are shown in FIG. 9: the transverse pitch Ptr, the longitudinal pitch Plg, the transverse cut DecTr and the longitudinal cut DecLg. The cutting rate, a parameter which determines for instance the acoustic quality of the panels, is the ratio between the surface cut (DecTr×DecLg) and the surface of the pitches (Plg×Ptr). A sufficiently high value is selected for the parameter X which determines the shift so as to reduce the force on the shafts. Indeed, the higher the value of parameter X, and particularly if X is not a whole number, the less cuts there are being simultaneously produced.  
         [0062]    Another important parameter is the ratio between the uncut longitudinal length, Plg-DecLg, and the shift pitch, Plg/X. If this ratio is a whole number, some of the first cuts of rectangular holes coincide with the second cuts shifted by a number of rows equal to said ratio. In this case, the number of cuts simultaneously produced is relatively high, which puts a relatively high bending load on the shafts, but with the cuts being produced in pairs, the radial forces on the knives compensate each other, which reduces the torque applied to the shafts. If the cutting parameters are chosen so that this ratio (Plg−DecLg)/(Plg/X) is not a whole number, the number of cuts being simultaneously produced is reduced, which reduces the bending force but increases the torque applied to the shafts.  
         [0063]    Table 1 shows a suitable choice of parameters corresponding to a ratio which is not a whole number and FIG. 10 shows a concrete example of a cutting pattern.  
         [0064]    The technique of the invention also allows to optimise the cutting of punctured holes, i.e. without discharge of material.  
         [0065]    The technology of the tools is identical in its principle. A U-shaped cut is produced on the first pair of tools  1  and  2 , as shown at  7 ′ (longitudinal direction) or  7 ″ (transverse direction) in FIG. 11. The teeth of type  111  of the simple tool  11  are consequently adapted. A fold, and no longer a cut as before, is produced at  8  on the second pair of tools. The teeth  311  of the simple tool  31  are of course consequently adapted: rounded at the level of the fold edge and sets compatible with the folding. FIG. 12 shows typical views of this type of puncture for the longitudinal direction and for the transverse direction.  
         [0066]    For these different applications, the diameter of the tools will be dictated by the considerations of material resistance which set the dimensions of the shafts but also by the contact conditions of the circular tool with the metal sheet. The radii of the tools  1  and  2  will therefore preferably be equal to or greater than 100 times the thickness of the metal sheet. In the case of punctures, different radii may also be chosen for tools  3  and  4 , tool  4  having for instance a radius that is sensibly greater than tool  3  so as to ensure good support for the metal sheet during the folding operation.  
         [0067]    In one particular embodiment, cutting and puncturing operations may be combined in a single machine along belts that are parallel to the travel direction of the metal sheet, the punctures being located in areas that do not come into contact with the shaping tools.  
                                                                           TABLE 1                           Example of parameters                    Ptr   DecTr   Plg   DecLg                   (Trans.   (Trans.   (Long.   (Long.   Shift           Rate   Pitch)   Displ.)   Pitch)   Displ.)   (Ptr/X)                            15   10   5   31.41   9.42   6.28           15   20   10   31.41   9.42   5.23           15   20   6.6   31.41   14.28   5.23           30   10   5   15.7   9.42   2.61           30   20   10   15.7   9.42   2.61           30   15   7.5   15.7   9.42   2.61