EP1400325B1 - Method and device for seperating blanks in a machine for cutting sheet material - Google Patents

Abstract

The device has a lower tool to support a sheet and including multiple openings (31). An upper tool supports punches (15) on a side facing towards the lower tool. Each punch is shaped to pass into the opening as the tools move towards each other. A suction device on each punch and a suction source connected with the devices selectively suck to hold blanks on sheet to the punches and release the blanks from the punches. An Independent claim is also included for a method of blanking a plate-like blankable sheet.

Description

The present invention relates to a method and a device for separating poses in a machine for cutting plate elements such as, for example, sheets of paper, cardboard or plastic.

The shaping of such sheets is generally carried out within a production line consisting mainly of a cutting station, a waste ejection station and a separation and reception station poses. The leaves are conveyed successively from one station to another by means of a bar of clamps, mounted on a chain train, gripping the front edge of the sheet. At each station, the chain train is stopped and each sheet undergoes a transformation constituting a new stage in the process of its shaping.

It is thus possible to produce, for example, packaging boxes, labels or any other generally pre-printed article from each of these sheets. Developed flat during their shaping, these items are commonly called poses by those skilled in the art.

These sheets are first introduced one by one cyclically in a platen press which will cut as many poses as the surface of the sheet may contain. To prevent the sheet from being dislocated once cut, it is planned to maintain all the poses to each other by attachment points, or small bridges of material, obtained by notches (not cutting) made in cutting nets of the press tool.

Although the poses have been judiciously disposed on the sheet, it is generally not possible to avoid the formation of interstitial wastes. Therefore, it is appropriate to pass each of these sheets in another station, called waste ejection station, to remove all the unwanted parts, by pinching between a plurality of ejectors. Following this operation, the sheet is still taken by the clamp bar to a so-called separation and receiving station poses, where these poses will be precisely detached from each other and carefully stacked on a pallet to form as many piles as there are poses in a leaf. Finally, the residual leaf, or skeleton, which includes its front edge, is released by the clip bar into an output station.

It is in the station for separating and receiving poses that the object of the present invention finds its use.

It is known to use, in a station for separating and receiving poses, a mobile upper tool and a fixed lower tool. The upper tool is constituted by a set of punches and the lower tool by a matrix with openings. In a downward vertical movement, the movable upper punches suddenly force all the poses through the apertures of the lower die and thus cause the breaking of the attachment points which connected each of the poses to the remainder of the sheet. The separation tools must therefore be adapted to the shape and layout of the poses of each new series of sheets to be worked. In general, the punches are mounted in register with the cutting lines of the press, on a base plate attached to an upper tool holder frame of the separating station. Below and opposite each punch is a corresponding opening or mesh of the lower die. The latter being formed of bars defining the meshes, or a widely openwork board.

The patents CH682651 and EP763407 describe in greater detail such devices that function satisfactorily for large or medium-sized poses. However, when it is necessary to separate poses of small size, or small width such as tabs, these poses tend to rotate or turn when they are ejected from the sheet. As a result, their stacking can no longer be assured and becomes random and incorrect. When the poses have a sufficiently large surface, which is generally the case when making packaging, these poses fall naturally by hovering and stacking correctly on the pallet. It can be seen that the quotient of the drop height by the surface of the pose is small enough so that the pose does not have time to turn around. However, this drop height, generally of the order of 65 mm, can only be very difficult to reduce because of various dimensional constraints, either at the level of the bulk of the mechanical parts within the station, or at the level of the use and maintenance, where a certain space between the tools is necessary, for example in case of jamming, to be able to easily remove damaged leaves.

US Patent 5,409,368 relates to an apparatus for separating an object from a support to which it is attached. In this patent, the problem is to separate from a plastic support groups of four pellets containing an insecticide. Part of this plastic support forming the lower part of the pellets, after separation from said support. This is a simple separation of a group of objects from their support sheet, the problem of stacking these groups of objects is not mentioned. In addition, in this patent, no elastic effect occurs during the separation.

The problem of improper stacking poses is even more marked when these are derived from a plastic sheet. Indeed, this kind of material often gives the poses a good elasticity when trying to bend them. However, this is precisely the case during the operation of the separation of the poses. When the punch presses on the pose, it bends more and more until its attachment points suddenly give way. At this time, the pose is projected down at very high speed under the effect of relaxation which occurs abruptly during the rupture of the material bridges. The speed of propulsion of the pose being much higher than that of the movement of the punch, its fall becomes totally uncontrollable. It has also been found that this "spring effect" of relaxation is all the more marked that the material used is resistant to breakage (this is the case of plastic compared to cardboard). The thickness (of the order of 0.2 to 0.6 mm) and the geometry of the pose also contribute to reinforcing this reaction, especially when the poses are particularly narrow and elongated and are in the form of small tongues for example.

Another disadvantage lies in the fact that sometimes the attachment points do not all break at the same time during the passage of the punch through the lower tool. This occurs regularly when the poses are treated in synthetic material, such as polypropylene, thin (typically between 40 microns and 0.1 mm). Thus, if all the points of attachment on the same side of the pose do not break while those on the other side break properly, this pose can not be completely detached and will remain hanging under the sheet by the persistent attachment points. In this case, there is either a jam of the machine, or a disturbance in the stack when the pose will fall when removing the rest of the sheet.

The object of the present invention is to eliminate the aforementioned drawbacks by describing a method and a device for separating and stacking poses allowing the control of the fall of the poses in order to avoid any reversal or other untimely disturbance of these during their stacking. For these purposes, the device of the present invention uses punches equipped with suction cups to capture the poses before starting the separation operation and hold them, by suction, until the punches have completely crossed the matrix and have descended preferentially as close as possible to the top of the stacks of poses. This device has the advantage of being able to control as long as possible the fall of all poses until the punches release them, then go back to perform a new cycle of separation of the poses.

To this end, the subject of the present invention is a device for separating and stacking poses, as described in claim 1, and a method implemented by this device according to claim 6.

• la figure 1 représente une vue schématique en coupe partielle du dispositif de séparation et d'empilage des poses de la présente invention, dans une première situation conforme au début du cycle de séparation des poses ;
• la figure 2 représente le même dispositif dans une seconde situation proche de la fin du cycle de séparation des poses ;
• la figure 3 représente une variante du dispositif illustré à la figure 1.

The invention will be better understood from the study of an embodiment taken in no way limiting and illustrated by the appended figures in which:

• Figure 1 shows a schematic partial sectional view of the separating device and stacking of the poses of the present invention, in a first situation according to the beginning of the separation cycle of the poses;
• Figure 2 shows the same device in a second situation near the end of the blank separation cycle;
• FIG. 3 represents a variant of the device illustrated in FIG.

Figures 1 to 3 show schematically the device 1 for separating and stacking the poses of the present invention in a simplified illustration. Certain proportions of the components of the component have deliberately not been respected in order to favor the clarity of the drawing and the understanding of the process applied to this device.

FIG. 1 gives a representation of this device in a first situation corresponding to the beginning of a cycle which is continuously repeated in a station for separating and receiving poses working sheets 2 previously cut out. These sheets are conveyed, within the machine, according to the direction given by the arrow 3.

The device 1 comprises an upper tool 10 movable in the vertical plane according to the arrow 4, a horizontal lower tool 30 on which stops the sheet 2 at the beginning of each cycle, and a pallet 35 receiving the poses 5 so as to form a stack 6. The upper tool 10 and the lower tool 30 have dimensions corresponding to the format of the sheet 2 whose poses must be separated by breaking their attachment points 7.

The lower tool 30, also called die, includes apertures 31 whose size is slightly greater than that of the poses 5 so that they can easily pass therethrough. The first operation is therefore to position the sheet 2 so as to obtain a perfect registration between the poses and the openings of the lower tool.

The upper tool 10 comprises a base plate 11, generally made of wood or plastic, on both sides of which are mounted various organs useful for the separation of the poses. For this purpose, there are essentially pressers 12 and punches 15. In order to simplify the drawing of Figures 1 to 3, only two pressers arranged on either side of a single punch have been shown. In reality, there are, of course, at least as many punches as there are poses 5 in the sheet 2.

The squeezers are intended to keep the sheet against the lower tool 30 to prevent it from moving when the poses are detached from the skeleton of the sheet. Each of these pressers generally consists of a support heel 13 placed at the end of a telescopic axis, represented here schematically by a spring 14. The other end of this spring being integral with the base plate 11. Another known embodiment, these pressers may be preferably constituted by pads of parallelepiped shape, cut in compressible foam.

The actual separation of the laying 5 will be performed by the punch 15, which is secured to the base plate 11 by a body 16 terminated at one end by a suction cup 17. The latter is advantageously expandable and presents itself for example in the form of a bellows. The body 16 of the punch and the base plate 11 of the upper tool are traversed by a conduit 18, one end of which opens into the suction cup 17, while the other end is extended by a pipe 19. The latter is connected to a pipe 20, arranged on the upper part of the base plate 11. As shown schematically in the figures, this pipe is finally connected to a source 23 suction air through at least one valve 21 and at least one member 22 regulating or measuring. Advantageously, these devices allow measurements of certain main characteristics of the air flow, such as its flow rate, its pressure or its speed, for example. The suction source 23 is preferably arranged outside the separation station, above the machine, for example. Usefully, each punch 15 of the upper tool 10 is connected to a pipe 20 and all of these pipes form an air distribution network connected to the suction source 23 through at least one valve 21 and one or more regulating or measuring members 22.

As shown in Figure 1, and thanks to the startup of the suction in the suction cup 17, the suction cup is able to grip the pose 5 even before the pressers 12 come into contact with the adjacent sheet portions at the pose. Therefore, the pose is completely controlled and controlled by the punch 15, this before any other operation.

The control of the entire air distribution network is in turn managed electronically, or mechanically using cams, by a control unit 24 symbolized in the figures by the rectangle drawn in broken lines. It thus becomes possible for the operator to be able to act at any time on the suction device by means of this control unit. The latter could be materialized by a control console allowing, on the one hand to display and know the parameters of the suction flow, and secondly to act accordingly, if necessary, to correct this flow. It would also be possible to provide a storage of the various adjustment parameters used according to the different work carried out in the station separation of poses.

Figure 2 shows the same device as that of Figure 1, but in another situation corresponding to a certain time later in the cycle of separation and stacking poses. Thus in the meantime, once the punch 15 has taken control of the installation 5 by suction of the air through the suction cup 17, the pressers 12 bear against the sheet 2 in the direct vicinity of the opening 31 Thanks to the continuous downward movement of the upper tool 10, the bellows of the suction cup 17 are compressed gradually until this compressive force exceeds the mechanical strength of the attachment points 7. From this moment, the installation is not abruptly ejected forward, but on the contrary remains under the control of the punch 15 which continuously continues its descent towards the stack 6. Arrived at the lowest level of its stroke, the punch releases the pose 5 following the repressurization of the suction cup 17, ordered by the unit of control 24, and the free circulation of air in the ducts 18. At this time, the drop height h ₂ of the laying 5 is minimal (of the order of 20 to 30 mm). In comparison, the rupture of the attachment points 7 took place at a much higher height h ₁ (of the order of 65 mm).

Once the suction cup 17 has separated from the installation 5, the upper tool 10 rises, as indicated by the arrow 4 in FIG. 2, until the pressers 12 separate in turn from the rest. of the sheet 2 and that the lower level of the suction cup 17 reaches at least the top of the sheet 2. Therefore, the latter can be removed from the separation station of the poses, in the direction given by the arrow 3. A new The cycle can then begin again as soon as a new sheet 2 arrives. As the stack 6 of sheets accumulates, the pallet 35 descends so that the upper surface of the stack remains at a constant level. . As a result, the height of fall h ₂ preferably remains also invariable.

Figure 3 shows a variant of the same device, but in a slightly different configuration. This variant suggests in particular another punch 45 in which the body 46 comprises a recess 40 allowing the folding of the suction cup 17 inside this recess. According to this arrangement, only a very small distance d separates the bottom of the suction cup 17 from the lower surface of the body 46. Being constituted by a sufficiently flexible bellows, the suction cup 17 can therefore, even before the attachment points yield completely retract into the recess 40 when the punch 45 begins to press the pose 5. As a result, it is the lower surface of the body 46 which, by coming into contact with the pose 5, will inflect the latter 5. down to breaking the attachment points 7 which connect it to the sheet 2. Maintained under constant suction, the fall of this pose 5 remains under the control of the punch 45 until the control device 24 orders to cut off the suction flow and let the air in the pipes 20 again.

In this variant, it has been imagined that the pressers come into contact with the sheet 2 before the suction cup 17 of the punch 15 grasps the application 5 by suction. The remainder of the process being as previously described during the continuation of the descent of the punch, and in a strictly reverse order during the ascent of the upper tool 10.

Whatever the variant chosen, the diameter of the pipes of the air distribution network is dimensioned according to the surface and the total number of poses per sheet. The power of the suction source is also adapted according to the work to be performed but, in many cases, tests have shown that the regulators 21 have a sufficient adjustment range to cover almost all needs.

Without this being an exclusion, it is not planned to reverse the pressurization in the ducts to inject a flow of air blowing into the suction cup in order to take off more quickly the laying of the lower surface of the sucker. This could be useful, however, if one were to deal with very small poses, very light and having a somewhat too adherent surface. Indeed, such a pose could then show some difficulty in separating naturally from the suction cup by simple effect of gravity. In this case, the suction source 23 would be transformed into a source 23 of air discharge, simply by reversing the polarities of the engine constituting it.

It would also be possible to cut the suction effect in the suction cup, in the interval between the breaking of the attachment points and the lowest point of the stroke of the upper tool 10. In this case, the effect beneficial control of the pose during its detachment of the sheet would still be preserved and this pose would in any case never ejected at a speed greater than that of the movement of the punch detaching it.

Workshop tests have also shown that it is advantageous to favor a bellows suction cup rather than a bell pad as generally found in sucking groups introducing the leaves into a production line. Indeed, the advantage of the expandable characteristic of the bellows suction cup lies mainly in the fact that it allows to enter the pose in all cases, even when there is a certain gap between the plane of the lower surface of the suction cup and the plane of the installation, or when the latter does not have a perfectly flat surface. Nevertheless, it would of course be possible to provide the arrangement of another type of suction cup in the device for separating poses as presented above.

1. a) mise en repérage des poses 5 de la feuille pré-découpée face aux ouvertures 31 de l'outil inférieur 30 ;
2. b) activation de l'aspiration de l'air dans les ventouses 17 des poinçons 15 ;
3. c) saisie des poses 5 par les ventouses 17 avant la rupture des points d'attache 7 par les poinçons 15 ;
4. d) séparation des poses 5 et contrôle de ces dernières par le maintien d'une dépression dans les ventouses 17 durant la rupture des points d'attache 7 ;
5. e) modification de la pression de l'air dans les ventouses 17 de façon à décoller les poses 5 des ventouses 17 ;
6. f) empilage des poses (5) décollées des ventouses (17);
7. g) remontée de l'outil supérieur 10 vers sa position initiale;
8. h) évacuation de la feuille 2 hors du dispositif 1 de séparation des poses.

The method for separating and stacking the poses applied to this device thus comprises successively the following main steps:

1. a) locating the poses 5 of the pre-cut sheet facing the openings 31 of the lower tool 30;
2. b) activation of the suction of the air in the suction cups 17 of the punches 15;
3. c) gripping of the poses 5 by the suction cups 17 before the breaking of the attachment points 7 by the punches 15;
4. d) separation of the poses 5 and control of the latter by maintaining a vacuum in the suction cups 17 during the breaking of the attachment points 7;
5. e) modifying the pressure of the air in the suction cups 17 so as to take off the poses 5 of the suction cups 17;
6. f) stacking the poses (5) detached from the suction cups (17);
7. g) raising the upper tool 10 to its initial position;
8. h) evacuation of the sheet 2 from the device 1 for separation of the poses.

In this process, it should also be noted that one could also add a step stipulating that the pressers 12 come into contact with the sheet 2, either before the capture of the poses by the suction cups, or after this seizure.

Finally, it will be recalled that the arrangements of the various organs of the device which are the subject of the present invention have been illustrated very schematically in the figures and that the invention is not limited to such illustrations but may include numerous improvements made in the context of the invention. claims.

Claims (9)

1. Device for separating and piling up blanks in a machine for cutting plate or sheet (2) elements, such as plastic plates or sheets, which have been previously cut in several blanks (5) that are held together by a number of nicks (7), comprising a horizontal and fixed lower tool (30) in which are provided as many openings (31) as there are blanks (5), an upper tool (10) cyclically movable in the vertical plane and having a plurality of telescopic pressing devices (12) on its lower surface for holding the said sheet (2) on the lower tool (30) and a plurality of punches to release the blanks (5) from the sheet (2) during the vertical movement of the punches (15, 45) passing through the plane of the lower tool (30) through said openings (31), so that said blanks (5) can be piled up, characterized in that said punches (15, 45) are equipped with suction cups (17) which are connected, by a distribution network (18, 19, 20) located above the upper tool (10), to a vaccum or a pressure source (23) able to generate changes in the air pressure within the suction cup (17), at least one part of each suction cup (17) projects below the lower end (46) of the punch (15, 45) to which it is fixedly attached, and in that said punches (15, 45), which are equipped with suction cups (17) and have passed through the lower tool (30), are arranged for being lowered to the vicinity of the top of the piles of the previously piled up blanks; and in that the device comprises a control unit (24) which controls the vaccum in the suction cups (17) so that the blanks are held by suction, until the punches (15, 45) have completely passed through the plane of the lower tool (30) and have been lowered to the vicinity of the top of the piles of the previously piled up blanks.
2. Device according to claim 1, characterized in that the suction cups (17) are expansible.
3. Device according to claim 1, characterized in that the distribution network (18, 19, 20) includes at least one valve (21) and/or at least one air regulation or measuring member (22).
4. Device according to claim 3, characterized in that the distribution network (18, 19, 20) and/or the vaccum or pressure source (23) are operated by a control unit (24).
5. Method for separating and piling up blanks according to claim 1, characterized in that it successively includes the following steps:

   a) Registering the blanks (5) of the pre-cut sheet (2) opposite to the openings (31) of the lower tool (30);

   b) Activating the vaccum in the suction cups (17) of the punches (15, 45);

   c) Gripping the blanks (5) by the suction cups (17) before the rupture of the nicks (7) by the punches (15, 45);

   d) Separating the blanks (5) and controlling them by keeping the suction cups (17) under low pressure during the rupture of the nicks (7);

   e) Lowering the punches (15, 45) to the vicinity of the top of the piles of the previously piled up blanks;

   f) Changing the air pressure in the suction cups (17) so as to release the blanks (5) from the suction cups (17);

   g) Piling up the blanks (5) released from the suction cups (17);

   h) Returning the upper tool (10) upward to its initial position;

   i) Evacuating the sheet (2) outside of the device (1) for separating blanks.
6. Method according to claim 5, characterized in that the pressing devices (12) contact the sheet (2) before the blanks (5) are gripped by the suction cups (17).
7. Method according to claim 5, characterized in that the pressing devices (12) contact the sheet (2) after the blanks (5) have been gripped by the suction cups (17).
8. Method according to claim 5, characterized in that the changing of the air pressure in the suction cups (17) comprises equalizing the value of this pressure with that of the ambient pressure in the vicinity of the device (1).
9. Method according to claim 5, characterized in that the changing of the air pressure in the suction cups (17) comprises increasing the value of this pressure to be above the value of the ambient pressure in the vicinity of the device (1).

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