EP0763407A1 - 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 a device for separating poses within a machine for cutting sheet elements such as, for example, sheets of paper or cardboard.

These machines are, among other things, used to cut from 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 faces of a box, some edges being completed with gluing or closing tabs.

Such a machine usually comprises first of all an introduction station 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 placed in position against front and side cleats. The sheet can then be gripped at its front edge by a series of clamps mounted along a transverse bar, each end of which is attached to a lateral chain train carrying the bar, therefore the sheet, to the following processing stations.

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

The sheet is normally then taken to an ejection station where the waste, that is to say the unused areas of the sheet between the tabs or between the formats, are pinched by upper and lower needles to be drawn towards the down in a bin.

The sheet is then brought into the blanking station, where the attachment points between the blanks and the sheet are broken by means of a male upper flat tool descending into a female lower flat tool, so as to release each poses falling on top of an underlying stack. The residual sheet is finally drawn into an exit station where it is released by the clamp bar.

When designing the layout of the cutting threads on the plate of the cutting station, a distinction is made between a "single cut" arrangement in which the poses are joined and a "double cut" arrangement in which the poses are separated longitudinally and transversely from each other by intermediate strips usually 5 mm wide. Although generating a larger area of paper or cardboard waste, 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 of 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 around the periphery of the blanks to be ejected. In the case of a double cut, this lower tool is therefore in the form of a grid, each longitudinal and transverse bar of which reproduces the shape of the intermediate strips separating the poses from one another.

The upper tool intended to be lowered sequentially into the lower tool comprises on the one hand pushers, that is to say wooden or foam pads, each fixed on the tool above a pose from which it takes the slightly smaller outline. This upper tool also comprises pressers, that is to say bars or pots situated respectively above the intermediate strips and mounted on elastic supports so as to press each strip against its bar in correspondence with the grid of the lower tool during separation of the poses.

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

However, shortly after the start of the removal of the residual sheet carried by the gripper bar towards the exit station, the transverse intermediate bands in the direction of movement are no longer supported except at their ends and hang in their middle downwards. When these transverse bands are relatively long, for example greater than 30 cm, the central arrows can reach 1 or 2 cm, causing these parts to subsequently hook onto the other bars of the grid of the lower tool. Beyond a certain rate, the residual leaves then tend to tear and fall back on the stacks of poses in an inappropriate manner.

The object of the present invention is an improvement of the separation equipment which makes it possible to obviate the problem of the rupture of the residual sheet during its removal. The design of this improvement must however remain simple in order to have reliable operation and a 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 poses from a plate element, these poses being surrounded by two lateral longitudinal bands, by two transverse front and rear 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 strip 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 strips and lateral strips have one or more suction orifices connected to a source of vacuum pneumatic, 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 raising of the upper tool during the withdrawal of this sheet.

In other words, the longitudinal pressers are modified so as to be able to take upwards, during the ascent of the upper tool, between two thirds and four fifths upstream of the residual sheet. The low points of the transverse bending intermediate bands are then clearly above the transverse bars of the lower tool. In this way, the risk of collision between the residual sheet and the lower grid tool has been eliminated in a simple and elegant manner. In addition, the depression is adjusted to a value just sufficient to only compensate for the weight of the sheet without creating an undue friction force which could cause a rupture at the level of the clamp bar. In particular, the effect of this depression decreases as the sheet is withdrawn by successive opening of the orifices, so as to always exert only a lifting force that is just sufficient.

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

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 makes it possible to provide a softened curvature between the raised sheet and the gripper bar located slightly above the lower tool.

Advantageously, the series of orifices provided in the two pressure rollers situated above each of the two lateral bands are offset inwards relative to the center line of the lower face. It has in fact been found that the lowering of the transverse bands causes a tightening of the residual sheet. This offset of the two series of orifices on each side makes it possible to ensure that the two lateral bands are always correctly understood.

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

Usefully, a reservoir-distributor in the form of a cylinder closed at its two ends is arranged transversely little above the longitudinal pressure cylinders, and is connected on the one hand to a vacuum pump and on the other hand to each pressure cylinders by a flexible hose, for example describing a loop. This arrangement is relatively simple to perform, and allows the installation of flexible supply pipes to compensate for the relative movements of the pressure rollers relative 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 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 non-limiting 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 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, the terms upstream and downstream will be used with reference to the direction of movement of the leaves, that is to say that a room on the upstream side is close to the entrance to the station. , while a part on the downstream side is close to the outlet. Similarly, the expressions longitudinal / transverse and left / right are to be considered with respect to the direction of travel of the strip, the left side being usually the driver side and the right side the side opposite to the driver of the machine. . With reference to FIG. 1, the installation separation equipment comprises a lower tool 10 and an upper tool 20.

The lower tool 10 is based on a grid tool 12 in the form of a board usually made of wood in which a plurality of openings 14 has been provided corresponding to the implantation of the poses cut from a sheet in a "double" mode. -chopped off". According to this layout, the poses are surrounded by two lateral bands, a rear band and a frontal band taken up by the drive clamps, and these poses are separated from each other by longitudinal and lateral intermediate bands of minimum width 5 mm. Therefore, the tool 12 is itself in the form of a grid, the transverse bars 13 and longitudinal 15 substantially resume the shape of the corresponding intermediate strips, but 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 cross-supports 16 themselves rest on a removable lower frame 18. Alternatively, these cross-supports 16 are an integral part of the frame 18.

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

The upper tool 20 also includes a rectangular frame 22 stiffened by side members 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 an opening 14 of the lower grid tool 12. These pushers 28 are are in the form of wooden plates or rigid elastomer blocks, possibly hollowed out in the middle, but whose outline takes up that of one of the poses cut from the sheet, therefore the outline of its aperture 14 in correspondence.

Between the pushers 28 are installed longitudinal and transverse pressers 40. The longitudinal pressers 36 are connected to the side member 24 of the frame 22 by a pair of elastic telescopic supports 39: an upstream and a downstream. Such a support 39 may be a rod whose lower end is fixed to the presser 36 and whose upper end slides in a lug connected to the crosspiece 24. A spring coaxial with the rod acts between the presser 36 and the lug of such so as to compress when this presser approaches 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 in a similar manner to the spar 24 by elastic telescopic supports 42. These pressers 36 and 40 being located between the pushers 28, they are therefore 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 orifices 38. For this, these pressers 36 are produced by means of tubes of rectangular section, and closed at their ends. The interior of each of these tubes is connected by a flexible tube 34 to a reservoir-distributor 30 itself connected to a vacuum pump by a supply duct 32. This reservoir-distributor 30 is in the form of a tube closed at its two 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 deform easily during the movement of the longitudinal pressers 36 relative to the spar 24.

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

In particular, the series of orifices 38 start from the downstream end of the longitudinal pressers 36 only from a distance (a) of the order of a third, or even a quarter, of the length of said presser 36.

The operation of the equipment for separating the blanks according to the invention will be better understood on examining FIGS. 2a to 2c, in which the same reference numbers in FIG. 1 have been reported.

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 and transverse pressers 36 have tightened the intermediate bands against the bars in correspondence with the grid tool 12. The penetration of the pushers 28 into the openings 14 causes the immediate breaking of the material bridges connecting each pose to the sheet. This break is accompanied by an ejection of the poses 3 downwards which fall squarely on the top of their respective stack 7.

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

More particularly according to the invention, the presence of suction orifices 38 means that atmospheric pressure presses this perforated sheet 1 'against the longitudinal pressers 36, this sheet therefore rising with the upper tool 20. As can then be seen, the transverse intermediate strips 2 in suspension are then found clearly above the transverse bars 13 with which they can no longer interfere. During its removal, the residual sheet 1 ′ therefore slides along the raised longitudinal pressers 36, the upstream orifices being re-opened as the sheet advances, which automatically readjusts the effect of the pressure atmospheric on the downstream part of this residual leaf.

As can be seen, the absence of suction orifices in the upstream part 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 tool 10.

With this improvement, the removal of the residual sheet 1 'is carried out reliably even at high rates. The modification essentially consisted in the production of a series of orifices in elements already present, and in the only addition of a buffer tank 30 and of a pipe of flexible pipes 34 correctly dimensioned. The cost of carrying out this improvement is therefore low and its maintenance poses no particular problem.

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

Claims (6)

Equipment for separating poses from a plate element, these poses 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 (10) in the form of a grid (12) whose bars (15) substantially reproduce the outline of the poses, and an upper tool (20) comprising, on the one hand, pushers (28), each fixed (26) above a pose, the outline of which is substantially smaller and slightly smaller, and on the other hand, pressers ( 36, 40) mounted on the tool above the bars by means of elastic supports (39, 42) so as to press each intermediate and lateral strip against its corresponding bar during the separation of the poses, characterized in that at least part of the pressers (36) located above the longitudinal intermediate bands and side bands has one or more suction orifices (38) connected to a source of pneumatic vacuum (30), 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 raising of the upper tool during the withdrawal of this sheet. Equipment according to claim 1, characterized in that the pressers (36) located above the longitudinal intermediate bands and lateral bands are in the form of longitudinal cylinders closed at their two ends, of lengths substantially identical to those of the tools (10 , 20), and whose flat lower faces have a series of suction orifices (38). Equipment according to claim 2, characterized in that the distance (a) between the downstream end of the pressing cylinder (36) and the start of the series of suction orifices (38) is between a quarter and a third of the length of cylinder. Equipment according to claim 2 or 3, characterized in that the series of orifices provided in the two pressure rollers situated above each of two lateral bands are offset inwards relative to the center line of the lower face . Equipment according to claim 2, characterized in that a series comprises a dozen orifices (38) with a diameter of the order of 1 millimeter and spaced 5 to 15 centimeters apart for a depression at the level of said orifices between 500 and 700 millibars. Equipment according to one of claims 2 to 5, characterized in that a reservoir-distributor (30) in the form of a cylinder closed at its two ends is arranged transversely slightly above the longitudinal pressure cylinders (36) , and in that it is connected on the one hand to a vacuum pump and on the other hand to each of the pressing cylinders by a flexible pipe (34).

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