EP0763407B1 - Equipment for separating blanks in a machine for cutting sheet elements - Google Patents

Abstract

The equipment processes blanks having extending around them two longitudinal lateral strips and two transverse front and rear strips being separated from one another by intermediate strips. The equipment comprises a bottom tool in the form of a grid whose bars reproduce the perimeter of the blanks and a top tool comprising pushers each secured above a blank of which it repeats the perimeter but on a slightly smaller scale. Pressers are disposed on the tool above the bars with the interposition of resilient supports so as to urge each intermediate and lateral strip against its companion bar during the separation of the blanks. At least some of the pressers are disposed above the longitudinal intermediate strips and lateral strips are formed with one or more suction orifices connected to a pneumatic negative pressure source.

Description

The present invention relates to separation equipment of poses within a machine for cutting plate elements such as, for example, sheets of paper or cardboard. A machine according to the preamble of claim 1 is described in CH-A-324 448.

These machines are, among other things, used to cut into each sheet one or more poses, also called formats, which, after folding and gluing, can be transformed into boxes. Each pose generally includes the six sides of a box, some edges being complete with adhesive or closing tabs.

Such a machine usually first comprises a station introduction in which the sheets, possibly pre-printed, are apprehended one by one from the top of a stack to be sent to a margin table where they are positioned against front cleats and lateral. The sheet can then be grasped at its front edge by a series of clamps mounted along a crossbar, each end of which is attached to a side chain train carrying the bar, so the sheet, in the following treatment stations.

The sheet is thus first transported to a station cutting of the poses according to a desired format, these poses no longer being retained at the sheet and / or between them only by a few bridges of material judiciously willing. This station usually comprises a platen press, the stationary upper plate carries a plate provided with a plurality of straight and curved slender knives. If desired, the cutting station can be preceded by a printing station also with platinum.

The sheet is then normally brought to a station where the waste, i.e. unused areas of the sheet enters the tabs or between formats, are pinched by upper needles and lower to be dragged down into a tray.

The sheet is then brought to the separation station of poses, where the attachment points between the poses and the sheet are broken at by means of a male upper plane tool descending into a lower plane tool female, so as to release each of the poses that fall on top of an underlying stack. The residual sheet is finally entrained in an exit station where it is released by the clamp bar.

When designing the layout of the cutting nets on the cutting station plate, a distinction is made between a layout in "simple cut" in which the poses are contiguous and a provision in "double cut" in which the poses are separated longitudinally and transversely from each other by intermediate bands usually 5 mm wide. Although generating a larger surface significant waste of paper or cardboard, imposition in "double cut" is preferred when the cut between two poses is rounded with different departures and arrivals, and when the adjacent edges of two poses are different colors with a somewhat uncertain border.

In the separation station, the sheet is brought flat on a lower tool in the form of a perforated horizontal board according to the perimeter of the poses to eject. In the case of a double cut, this lower tool is therefore in the form of a grid with each bar longitudinal and transverse reproduces the shape of the intermediate bands separating the poses from each other.

The upper implement intended to be lowered sequentially into the implement lower comprises on the one hand pushers, that is to say wooden skids or foam, each attached to the tool above a pose from which it resumes the outline is slightly smaller. This superior tool also includes pressers, i.e. bars or studs located respectively above the intermediate bands and mounted on elastic supports so as to press each strip against its corresponding bar of the grid of the lower tool during the separation of the poses.

In the case of imposition of a sheet in "double cut", the residual sheet after separation of the poses also occurs under the form of a grid of paper or cardboard initially supported by each bars of the lower tool.

However, shortly after the start of removal of the residual sheet taken by the gripper bar to the exit station, the bands transverse intermediates in the direction of movement are no longer supported only at their ends and hang down their midpoints. When these transverse bands are relatively long, for example greater than 30 cm, the central arrows can reach 1 or 2 cm, making these parts will then hook onto the other bars of the tool grid inferior. Beyond a certain rate, the residual leaves have then tendency to tear and fall back on stacks of poses so untimely.

The object of the present invention is to improve separation equipment that obviates the problem of rupture of the residual sheet when it is removed. The design of this improvement must however keep it simple for reliable operation and low cost of production.

• un outil inférieur sous la forme d'une grille dont les barreaux reproduisent sensiblement le contour des poses, et
• un outil supérieur comprenant d'une part des pousseurs, chacun fixé au-dessus d'une pose dont il en reprend sensiblement le contour en légèrement plus petit, et d'autre part des presseurs montés sur l'outil au-dessus des barreaux au moyen de supports élastiques de telle sorte à appuyer chaque bande intermédiaire et latérale contre son barreau en correspondance pendant la séparation des poses, du fait qu'une partie au moins des presseurs situés au-dessus des bandes intermédiaires longitudinales et bandes latérales présentent un ou plusieurs orifices aspirants reliés à une source de dépression pneumatique, le nombre des orifices et leurs sections, ainsi que la valeur de la dépression étant tels que ces presseurs soulèvent au moins la partie amont de la feuille résiduelle lors de la remontée de l'outil supérieur pendant le retrait de cette feuille.

These purposes are achieved in a device for separating blanks from a plate element, these blanks being surrounded by two lateral longitudinal bands, by two front and rear transverse bands, and being separated by intermediate bands, this equipment comprising:

• a lower tool in the form of a grid whose bars substantially reproduce the outline of the poses, and
• an upper tool comprising, on the one hand, pushers, each fixed above a pose, the outline of which is substantially smaller and slightly smaller, and, on the other hand, pressers mounted on the tool above the bars at means of elastic supports so as to press each intermediate and lateral band against its corresponding bar during the separation of the poses, owing to the fact that at least part of the pressers situated above the longitudinal intermediate bands and lateral bands have one or more suction orifices connected to a source of pneumatic vacuum, the number of orifices and their sections, as well as the value of the vacuum being such that these pressers raise at least the upstream part of the residual sheet during the ascent of the upper tool during removing this sheet.

In other words, the longitudinal pressers are changed from so that you can take it up when the tool is raised upper, between two-thirds and four-fifths upstream of the leaf residual. The low points of the transverse intermediate bands bending are then clearly above the transverse bars of the lower tool. We thus eliminated in a simple and elegant way any risk of collision between the residual sheet and the lower grid tool. In addition, the depression is adjusted to a value just sufficient for only compensate for the weight of the sheet without creating an undue friction force which could cause cause a break in the clamp bar. In particular, the effect of this depression decreases as the leaf is withdrawn by successive opening of the orifices, always only exerting a force of just sufficient lifting.

According to a preferred embodiment, the pressers located above the longitudinal intermediate bands and side bands are are in the form of longitudinal cylinders closed in two ends, of lengths substantially identical to those of the tools, and of which their flat lower faces have a series of suction orifices. The use of cylinder as longitudinal pressers greatly simplifies the connection of the orifices to the source of vacuum. In addition, the undersides planes constitute homogeneous surfaces against which the longitudinal strips of the residual leaf when removed.

Preferably, the distance (a) between the downstream end of the pressure cylinder and the start of the series of orifices is between a quarter and a third of the length of the cylinder. This allows for a curvature softened between the raised sheet and the clamp bar located slightly above of the lower tool.

Advantageously, the series of orifices formed in the two pressure rollers located above each of the two side bands are offset inward from the center line of the face lower. It has indeed been observed that the lowering of the transverse bands causes a tightening of the residual leaf. This mismatch of the two series of holes on each side ensures that the two bands side are always correctly understood.

According to an embodiment based on a depression at the level orifices between 500 and 700 millibars, a series includes a dozen orifices with a diameter of the order of 1 millimeter and spaced 5 to 15 centimeters.

Usefully, a tank-distributor in the form of a cylinder closed at both ends is arranged transversely a little above longitudinal pressure cylinders, and is connected on the one hand to a pump with vacuum and on the other hand to each of the pressing cylinders by a flexible pipe, by example describing a loop. This arrangement is relatively simple to realize, and allow the installation of flexible supply pipes for compensate for the relative movements of the pressure rollers with respect to the upper tool, these pipes being easy to access for monitoring and maintenance.

• la figure 1 est une vue schématique en perspective du dessous d'un équipement de séparation de pose selon un mode de réalisation de l'invention, et
• les figures 2a, 2b et 2c sont des vues schématiques de côté de l'équipement respectivement lors de l'arrivée d'une feuille, lors de la séparation des poses, et lors du retrait de la feuille résiduelle.

The invention will be better understood from the study of an exemplary embodiment taken on a nonlimiting basis and illustrated in the appended figures in which:

• FIG. 1 is a schematic perspective view from below of a laying separation equipment according to an embodiment of the invention, and
• FIGS. 2a, 2b and 2c are schematic side views of the equipment respectively when a sheet arrives, when the blanks are separated, and when the residual sheet is removed.

In the rest of the presentation, we will use the terms upstream and downstream with reference to the direction of movement of the sheets, i.e. a part upstream side is close to the station entrance, while a room on the downstream side is close to the exit. Similarly, the expressions longitudinal / transverse and left / right are to be considered in relation to the direction strip travel, the left side is usually the driver side and the right side the side opposite to the machine. Referring to Figure 1, the installation separation equipment comprises a lower tool 10 and upper tool 20.

The lower tool 10 is based on a grid tool 12 in the form a board usually made of wood in which a plurality has been provided openwork 14 corresponding to the layout of the poses cut from a sheet in a "double-cut" mode. According to this layout, the poses are surrounded by two side bands, a rear band and a band front taken by the grippers, and these poses are separated between them by intermediate longitudinal and lateral width bands minimum of 5 mm. As a result, the tool 12 presents itself in the form of a grid whose transverse bars 13 and longitudinal 15 resume substantially the shape of the corresponding intermediate bands, but in having a slightly smaller width.

In the illustrated embodiment, the grid tool 12 is supported by a plurality of cross-supports 16 located under the front bar, under each of the transverse bars 13 and under the rear bar. These support sleepers 16 themselves rest on a lower frame 18 removable. Alternatively, these cross-supports 16 are an integral part of the box 18.

Usually, these frames and crosspieces are made from profiled metal bars, preferably aluminum for their relative lightness. The higher than wide profile of these profiles ensures great rigidity in the vertical direction of the tool 10. The external faces of the crosspieces upstream and downstream of the frame have a groove making it possible to exit then to reinstall this tool in the station by passing it through a side window and the sliding of two upstream and downstream bacon belonging to the fixing the station. The frame is further completed in its four points of centering studs with conical part and receiving locking pins. We can easily remove this lower tool 10 to change the grid tool 12 into function of the new installation layout of the production series next.

The upper tool 20 also includes a rectangular frame 22 stiffened by beams 24, both also made from particularly rigid profiles in the vertical direction.

To this frame is first fixed a plurality of pushers 28, and this rigidly by means of fasteners 26. Each pusher 28 is in vertical correspondence with a hole 14 in the lower grid tool 12. These pushers 28 are in the form of wooden plates or blocks rigid elastomer, possibly hollowed out in the middle, but the contour resumes that of one of the poses cut from the sheet, so the outline of its opening 14 in correspondence.

Between the pushers 28 are installed longitudinal pressers 36 and transverse 40. The longitudinal pressers 36 are connected to the beam 24 of the frame 22 by a pair of elastic telescopic supports 39: a upstream and downstream. Such a support 39 may be a rod whose end lower is fixed to the presser 36 and whose upper end slides in a tab connected to the crosspiece 24. A spring coaxial with the rod acts between the presser 36 and the tab so as to compress when this presser closer to its spar. The length of the rod is such that the face bottom of the presser 36 is located slightly below, on the order of 5 to 10 mm, from the underside of the pushers 28. The transverse pressers 40 are mounted analogously to the spar 24 by supports elastic telescopic 42. These pressers 36 and 40 being located between the pushers 28, so they are found in vertical correspondence respectively with the bars 15 and 13 of the grid tool 12.

More particularly according to the invention, the longitudinal pressers 36 have a series of suction ports 38. For this, these pressers 36 are made by means of tubes of rectangular section, and closed in their extremities. The interior of each of these tubes is connected by a flexible tube 34 to a distributor-reservoir 30 itself connected to a vacuum pump by a supply conduit 32. This distributor-reservoir 30 is provided under the form of a tube closed at both ends and arranged transversely to the longitudinal pressers 36, and this between the pushers 28 and the side members 24. The tubes 34 are made of flexible material, and can even take the form of a loop, so as to easily deform during the movement of the longitudinal pressers 36 relative to the side member 24.

In the illustrated embodiment, each longitudinal presser 36 presents the same series of a dozen suction ports 38, each orifice having a diameter on the order of 1 mm and being spaced on the order of 5 to 15 cm from each other. The depression applied in the distributor-reservoir 30 is such that, taking into account the pressure drops in the flexible tubes 34, a vacuum of the order of 500 to 700 is obtained millibars at the suction ports 38.

In particular, the series of orifices 38 do not start from the downstream end longitudinal pressers 36 only from a distance (a) of the order of third or even a quarter of the length of said presser 36.

The operation of the plant separation equipment according to the invention will be better understood on examining FIGS. 2a to 2c, in which have been reported the same reference numerals in Figure 1.

FIG. 2a illustrates how, the upper tool 20 being raised, a gripper bar 5 brings a sheet 1 on top of the fixed lower tool 10, and more particularly on the top of the grid tool 12. The function suction of the longitudinal pressers 36 has no effect at this time.

FIG. 2b illustrates how the upper tool 20 is lowered in the lower tool 10 until the pushers 28 enter the openings 14. Just before this return of the pushers, the longitudinal pressers 36 and transverse tightened the intermediate strips against the bars in correspondence of the tool-grid 12. The penetration of the pushers 28 into the openwork 14 causes the material bridges connecting each laying on the sheet. This rupture is accompanied by an ejection of the poses 3 towards the bottom which fall squared on top of their respective pile 7.

FIG. 2c illustrates the ascent of the upper tool 20 and the start of the clamp bar 5 to pull the residual sheet 1 'towards the output station.

More particularly according to the invention, the presence of orifices aspirants 38 causes atmospheric pressure to plate this perforated sheet 1 ' against the longitudinal pressers 36, this sheet therefore rising with the tool upper 20. As can be seen then, the intermediate bands transverse 2 in suspension are then found clearly above the transverse bars 13 with which they can no longer interfere. When of its removal, the residual sheet 1 'therefore slides along the pressers longitudinal 36 raised, the upstream holes being re-opened as and sheet advance measurement, which automatically readjusts the effect of the atmospheric pressure on the downstream part of this residual sheet.

As can be seen, the absence of suction ports in the upstream portion of the longitudinal presser 36 allows the sheet to describe a softened curve towards the clamp bar 5 situated at a lower level, practically at the level of the upper face of the tool 10.

Thanks to this improvement, the removal of the residual sheet 1 ' works reliably even at high speeds. The modification has essentially consisted in the realization of series of orifices in elements already present, and by the simple addition of a buffer tank 30 and a pipeline of flexible pipes 34 correctly dimensioned. The cost of this improvement is therefore low and its maintenance does not pose no particular problem.

Many improvements can be made to this equipment within the scope of the claims.

Claims (6)

1. Equipment for separating blanks from a flat element, the blanks having extending around them two longitudinal lateral strips and two transverse front and rear strips and being separated from one another by intermediate strips, the equipment comprising :

   a lower tool (10) in the form of a grid (12) whose bars (15) substantially reproduce the perimeter of the blanks, and

   an upper tool (20) comprising pushers (28), each secured (26) above a blank of which it substantially repeats the perimeter but on a slightly smaller scale, and pressers (36, 40) disposed on the tool above the bars with the interposition of resilient supports (39, 42) so as to urge each intermediate and lateral strip against its companion bar during the separation of the blanks, characterized in that at least some of the pressers (36) disposed above the longitudinal intermediate strips and lateral strips are formed with one or more suction orifices (38) connected to a pneumatic negative pressure source (30), the number and cross-sections of the orifices and the value of the negative pressure being such that the pressers raise at least the upstream part of the residual sheet as the upper tool rises during the withdrawal of the sheet.
2. Equipment according to claim 1, characterized in that the pressers (36) disposed above the longitudinal intermediate strips and lateral strips are in the form of longitudinal cylinders closed at both their ends and having substantially the same lengths as the tools (10, 20), the lower plane surfaces of the longitudinal cylinders being formed with a row of suction orifices (38).
3. Equipment according to claim 2, characterized in that the distance (a) between the downstream end of the presser cylinder (36) and the start of the row of suction orifices (38) is between one-quarter and one-third of the cylinder length.
4. Equipment according to claim 2 or 3, characterized in that the rows of orifices in the two presser cylinders (36) disposed above each of two lateral strips are offset inwardly from the centerline of the lower surface.
5. Equipment according to claim 2, characterized in that a row comprises twelve orifices (38) which have a diameter of the order of 1 millimeter and which are spaced apart from one another by from 5 to 15 centimeters, for a negative pressure of from 500 to 700 millibars in the orifices.
6. Equipment according to any of claims 2 to 5, characterized in that a combined distributor and reservoir (30) in the form of a cylinder closed at both its ends is disposed transversely slightly above the longitudinal presser cylinders (36) and is connected to a vacuum pump and to each of the presser cylinders by a flexible pipe (34).

Images