EP0574745B1 - Device for separating piled sheets from synthetic material, paperbound or the like - Google Patents

Abstract

The separating device consists of a magazine (1) in which piled sheets (6) of plastic or the like are arranged, and has movable suction devices (13) in order to move the separated sheets (6) to a working station (28), the sheets (6) in the pile (12) being supported, lying horizontally, by supports (8) on the lower edge (7) of the magazine (1) and the lowermost sheet (6) being exposed between the supports and accessible to the suction device (13). In order to separate the sheets reliably with relatively simple means and, preferably, to bring them reproducibly into engagement in an accurate position with the suction device (13), provision is made according to the invention for a rotatably driven shaft (8) to be arranged along the two lower edges (7) of the magazine (1) as a support, the cross-section of the shaft being recessed in the region of the length of the sheets (6) to form a shoulder, the depth of the shoulder being equal to the thickness of the sheet to be separated, and for the suction devices to be able to be advanced towards the sheet (6) and retracted arranged so as to be approximately centrally between the edges (7) of the magazine (1). <IMAGE>

Description

The invention relates to a device for separating sheets of plastic, cardboard or the like stacked in a magazine with at least one movable suction device and for transporting the separated sheets to a work station, the sheets in the stack lying essentially horizontally by holders at the lower edge of the magazine are supported and in between the lowest sheet is exposed and is accessible to the vacuum cleaner, a rotatably driven shaft being arranged along at least one of the two lower edges of the magazine as a holder.

With somewhat stiffer sheets of cardboard, plastic material or similar materials, there is often the problem of separating such sheets, sheets or blanks when working from the stack. This separation is generally difficult when the sheets or sheets inadvertently stick together.

Separating devices are known in which sliders move the bottom sheet in each direction over the lower lateral holder until the sheets have lost their grip on the edge in question and hang freely down into the opening, after which an oppositely arranged further slider is opposite Performs sliding movement and also pushes the opposite edge of the sheet from its lower bracket, so that the sheet can then fall freely down into other devices. As a result of the weight of a large stack on the bottom sheet in each case, this adheres to a greater or lesser extent to sheets above it, with the result that the slides grip several sheets at the same time, so that separation is not reliably guaranteed. Devices have also been built in which two slide arrangements of this type lie one below the other in order to achieve separation in the underlying second stage with certainty.

In particular, however, if there are corrugations in the longitudinal direction of the edge of the respective sheet, which is particularly often found in sheets made of plastic material, the slides of the known separating device only grip at points, or the slides do not find any point of engagement at all, precisely because the slider is bent up of the leaf margin was a gap. Separation with this device is therefore unreliable in the case of corrugated sheets.

A separating device of the type mentioned is known from DE-A-24 36 354. There are transport rollers on two opposite lower edges of the magazine, between which, arranged deeper, pairs of take-off cylinders with suction devices are rotatably arranged. In the known device, a group of approximately 3 to 6 sheets, which are located in the lower region of the magazine, are continuously bent upward in a convex manner. The lowest sheet in each case is removed by rolling it off the stack or by partially rolling the sheet onto one of the successively engaging pairs of take-off cylinders with the inclusion of suction air. In the course of further, fully continuous movements, the sheet is passed on to a central takeover cylinder. The known device is complex, complicated and allows the sheets to be separated only by comparatively strong bending of the sheets, in particular when the bottom sheet from the transport roller onto the removal cylinder pairs and then even onto the central take-over cylinder, each encompassing the curved surfaces partly in opposite directions , is led and guided.

The invention is therefore based on the object to provide a separating device of the type described in more detail above, with which the sheets of plastic, cardboard or the like can be reliably separated with simpler means and can preferably be reproducibly brought into engagement with the mentioned suction device in a precise position .

It is already part of the idea according to the invention to use suction cups to pull off the bottom sheet in each case, although the use of suction cups for separating them is known per se in conventional devices. What is special about the present invention is the consideration of combining agents known per se with new agents for a surprising effect.

With regard to the described device, the object is achieved in that the shaft is driven in an oscillating manner so that the bottom sheet is brought into a downwardly bent position, the cross section of the shaft is excluded in the region of the length of the sheet to form a shoulder, which The depth of the shoulder is equal to the thickness of the sheet to be separated and that a sucker is arranged to move and retract from below against the sheet approximately in the middle between the edges of the magazine. Through the measures according to the invention, the bottom sheet falls into the aforementioned shoulder-shaped recess of the at least one shaft and is gripped even at a corrugated sheet edge laterally from the shoulder at numerous points in such a way that with certainty only the bottom sheet when turning the shoulder in the direction of the opposite holder is gripped and subjected to a bending movement due to the shortening of the distance to the opposite holder. The shoulder has a small edge which, prior to engagement with the sheet edge, lies in the direction of the stack height, that is to say is essentially arranged vertically, and a support surface at an angle of approximately 90 ° to which the sheet edge comes to rest. As a result of the rotary movement of the edge of the shoulder between these two surfaces in the direction of the opposite holder, in addition to the shortening of the distance to the opposite holder, the last-mentioned bearing surface for opening between the two holders is inclined downward. As a result, pulling out the bottom sheet is even easier and the edges of the sheets are protected in the area of the shoulder of the shaft. Pulling out the bottom sheet in each case with the aid of the suction device permits reliable separation, the position of the sheet relative to the suction device preferably being taken reproducibly.

The separation takes place particularly favorably if, according to the invention, both mutually opposite holders are also designed as partially recessed shafts, which are driven to rotate in opposite directions synchronously with one another. The rotation of the shafts about their longitudinal axes is advantageously oscillating, the arc of the oscillation needing to be only in a range between 10 and 40 °, and in practice it has even been found that a rotation over an angular range of between 20 ° and 30 ° brings good results. This enables the device to separate a large number of sheets per unit of time.

It is also advantageous according to the invention if the shaft has an approximately semicircular recess in cross section next to the shoulder. In general, a normal wave is round and its outer surface is imagined as a cylinder jacket. The shaft extends under the magazine edge over the entire length of the magazine and beyond its side walls thus certainly longer than the longitudinal edge of the sheet to be separated. For the purpose of simplified production, the shoulder mentioned can extend beyond the length of the sheet edge and possibly even beyond the corresponding magazine length. The recess which is semicircular in cross section, on the other hand, is only provided over the length of the leaf edge, if only for reasons of stability, for exact shaft movements. In the area of the sheet to be separated, the shaft is flattened, so that a space is created between the waves, which is in any case wider than the smallest distance between two opposite shafts with a circular cross-section without the recess according to the invention. However, an enlarged space has advantages for the movement of machine elements, as will be described in the following, which could not be moved in a comparably good manner without this enlarged space.

In a further advantageous embodiment of the invention, the suction cup is translationally movable by means of a first drive, and the first drive is fastened to a second drive for carrying out a rotary movement. In this way, the suction cup can be moved in a straight line so that it can be moved from below through the opening of the Magazine can be moved between the opposite holders to the lower surface of the bottom sheet. The first drive can then move the sheet sucked by vacuum in a straight line in the opposite direction to the advancing movement of the suction device downward from the stack. Since this first drive is now attached to a second rotary drive, the suction device can additionally perform a rotary movement together with the attached and separated sheet and transport the separated sheet to another location, e.g. a place where the isolated sheet is removed and subjected to further treatments.

In a preferred embodiment, the sheets to be separated are rectangular and sometimes have a greater length than width, so that it is expedient to provide correspondingly long shafts as a holder arn magazine below and, accordingly, to arrange several suction cups in a row one behind the other so that the elongated sheet over its entire length can be recorded and held in several places. It is expedient to arrange two so-called first drives spaced apart over the length of the sheet to be separated, although a first drive could also be provided for each suction cup. It is particularly expedient to provide two first drives which can move any number of suction cups simultaneously using suitable holding means, in which case both first drives must of course then be moved in phase. Then the second drive for the rotary movement can simultaneously turn both first drives (also in phase with one another) and thus rotate all suction cups in a row or possibly even several rows simultaneously and in phase.

In an expedient embodiment, according to the invention, a translationally movable pressure plate is attached to the first drive, on which the suction pad can be moved in a straight line by a third drive in the same direction as the pressure plate. The above-mentioned machine element is thus a pressure plate in this embodiment, which is namely arranged on the side facing the sheet to be separated and against which this sheet can be placed if the single suction cup or the plurality of suction cups is translational / linear via the third drive mentioned withdrawn relative to the Andrudkplatte. For this purpose, the pressure plate preferably has openings into which the suction cup (s) can be drawn, with the result that the surface of the pressure plate is flush, smooth or flat and the sheet to be separated can be applied accordingly. The third drive mentioned will therefore be conveniently arranged on the back of the pressure plate, which is turned away from the magazine, so that the respective suction cup can be retracted into the outer contour of the pressure plate (with the aid of the third drive), and then the pressure plate with all of it Suckers and their third drives can be rotated by the second drive to remove the separated sheet.

The rotationally coordinated rotary movements of the one or two shafts on the magazine edge on the one hand and the transport shaft of the second drive on the other hand are carried out via pneumatically, hydraulically or mechanically controlled levers.

It is also advantageous according to the invention if at least one wall of the magazine for centering the stacked sheets is arranged to be displaceable perpendicular to the wall plane. Preferably, one wall of the magazine is pressed gently via an air cylinder in the direction of the opposite, stationary magazine wall, thereby centering the stack of sheets to be separated, with the advantage that the position of each sheet to be separated is always the same and can be reproduced very precisely. This allows you to attach every single sheet to the suction cup in an exact position. This brings considerable advantages for further precise placement of the sheet at subsequent work places.

While it is sufficient in some embodiments to provide only one of the two holders on the lower magazine edge as a shaft with a shoulder and preferably a semicircular recess, the accuracy of the arrangement of two opposite shafts as holders on the lower magazine edge may be required in special applications. It is inevitable that certain plastic sheets, which are produced, for example, by cutting from a band, have tolerances that experience has shown to be 100% effective in one place if only one holder is designed as a shaft. However, you have both holders as shafts the tolerance is spread over both sides, is halved and practically negligible.

Figur 1

schematisch eine Querschnittsansicht durch das Magazin mit darunter angeordnetem Sauger mit den Antrieben, wobei links eine nachfolgende Arbeitsstelle angedeutet ist,

Figur 2

eine Schnittansicht entlang der Linie II-II der Figur 1,

Figur 3

eine vergrößerte Einzelansicht der Einzelheit III in Figur 1 und

Figur 4

eine teilweise abgebrochene Draufsicht entlang der Linie IV-IV der Figur 3.

Further advantages, features and possible applications of the present invention will become apparent from the following description in conjunction with the accompanying drawings. Show it:

Figure 1

schematically a cross-sectional view through the magazine with the suction device arranged underneath with the drives, a subsequent work location being indicated on the left,

Figure 2

2 shows a sectional view along the line II-II in FIG. 1,

Figure 3

an enlarged individual view of detail III in Figure 1 and

Figure 4

a partially broken plan view along the line IV-IV of Figure 3.

1 and 2 show the main parts of the preferred embodiment of a separating device shown here as an example. The magazine, generally designated 1, is to be thought of as rectangular in plan view and has two longitudinal walls 2, 2 'and two transverse walls 3, 3', each wall consisting of two parallel wall parts, which, however, are not described in more detail here. The walls 2, 2 ', 3, 3' are vertical (perpendicular), so that they can be loaded from above with plastic sheets 6 produced by a cutting device 4 from a web 5. The bottom sheet 6 falls to the lower edges 7 of the magazine 1, below which two shafts 8 are arranged parallel to each other. The axis of rotation 9 of the shafts 8 lies almost in the extension of the inner surface of the walls 2, 2 ', only slightly shifted outside the opening 10, as can be seen more clearly from FIG. The opening 10 extends from the inner lower edge of the edge 7 of the one longitudinal wall 2 to the opposite lower left edge of the right edge 7 of the right longitudinal wall 2 'and is rectangular in plan view in the direction of the arrow 11 (FIG. 2). The respective shaft 8 touches the lower edge 7 of the side wall 2, 2 'of the magazine 1, which results in contact points X (FIG. 3) and also on the opposite side (without designation); in practice small contact areas because the leaves are not 100% rigid and straight. On the contrary, they have to be resiliently flexible, because otherwise the separating device described here would not work.

The two shafts 8 are, so to speak, the oats on the lower edge 7 of the magazine 1, on which the sheets 6 are supported.

One sheet 6 after the other falls into the box-shaped space of the magazine 1 until the height of the stack 12 shown in FIGS. 1 and 2 is reached.

In the middle, below the opening 10, there are five pneumatic suction devices 13 in a row, the front of which can be seen in FIG. 1, while all five suction devices 13 are shown in the cross-sectional view in FIG. As shown in FIG. 2, they lie in front of the left rear shaft 8.

Each suction cup 13 is attached to the outer end 14 of the piston rod 15 of a so-called third drive 16, so that there are as many third drives 16 as suction cups 13. These third drives 16 are fastened to a pressure plate 17, which extends over almost the entire length ( L) and extends transversely to almost the entire width of the sheets 6. This pressure plate 17 thus holds the third drive 16 in each case and enables a relative movement of the suction cups 13 in the direction of the double arrow 18 in a straight line upwards and for retraction vertically downwards. The pressure plate 17 in turn is attached to the outer ends of further piston rods 19 of a so-called first drive 20, which is attached in the form of an air cylinder 20 to a transport shaft 21 which is supported in two bearings 22 as shown in FIG. 2. The axis of rotation of the transport shaft 21 is designated 23.

The rotary movement of the transport shaft 21 takes place via a controlled lever 24; the rotation of the respective shaft 8 via a lever 25. The drives of the levers 24 and 25 are not shown. In the longitudinal distance of the transport shaft 21, two air cylinders 20 are arranged, so that the pressure plate 17 is securely and reliably held in two places. Separated from the movement of the suction cups 13 with respect to the pressure plate 17, as represented by the double arrow 18, the pressure plate 17 itself can also be moved relative to the transport shaft 21 in the direction of the double arrow 26 via the so-called first drive 20 (air cylinder). The stroke of the translational up and down movement 26 of the pressure plate 17 is greater than the stroke of the straight up and down movement of the suction cups 13 according to the double arrow 18.

In addition, the rotary movement of the transport shaft 21 in the direction of the curved double arrow 27 in FIG. 1 causes the suction cups 13 to move from the position shown in solid lines in FIG. 1 to the position shown in broken lines, in which the suction cup is denoted by 13 '. In addition, a heated plate 28 is shown with a plurality of vacuum openings 29, the vacuum openings on the right surface being thought to be arranged. This heated plate 28 can be moved up and down vertically in the direction of the double arrow 30.

The sheets 6 to be separated in the stack 12 are centered by moving the right rear side wall 3 'of the magazine 1 with the aid of an air cylinder 31, which allows the side wall 3' to be displaced in the direction of the double arrow 33 via a piston rod 32.

The respective shaft 8 is supported in bearings 34. We now turn to the design of the respective shaft 8 and in this connection consider FIGS. 3 and 4. In FIG. 3, at the bottom left you can see the right end of the pressure plate 17, which has broken off to the left, as well as the isolated sheet 6 above it and the stack 12 in the magazine 1. Under its edge 7 is the shaft 8, the diameter D of which is shown in FIG.

While on the respective outer length D (FIG. 4) the shaft 8 is left essentially circular (at best the shoulder 35 can pass through), the cross section of the shaft 8 shown in FIG. 3 is provided with a recess forming a shoulder 35. Its depth t is as thick as the sheet 6 to be separated. The radially arranged plane 36 of the shoulder therefore represents a very short area, i.e. it corresponds to the height t. This plane appears in the view in FIG. 4 as line 36. The right edge 37 of sheet 6 bears against this shortly before and at the latest after the start of rotation of shaft 8. For clarification, this right edge 37 of the sheet 6, which appears as a line, is shown lying at a somewhat exaggerated distance from the edge 36 in FIG.

Perpendicular to the narrow surface 36 of the shoulder 35 is the somewhat larger contact surface 38 of the shoulder 35, which extends to the edge 39 which touches the circle of the shaft 8 at the point 39 shown in FIG. This longitudinal edge 39 of the shoulder 35 is shown in FIG. 4 as a line which can only be seen in broken lines in the area below the sheet 6. Seen from above in the direction of the line IV-IV, the shoulder 35 thus extends from the line 37 to the line 39. This shoulder can also be pulled outward beyond the circular end region d of the shaft 8. However, the device works just as well if the circumferential surface over the ends d of the shaft 8 is really cylindrical.

It can be seen from FIG. 3 that the shaft 8 at the radial distance from the shoulder 35 is also provided with a semicircular recess 40, which can be seen in FIG. 3 as a partial circular surface, while FIG. 4 shows the empty space 40. This - in cross section - semicircular recess 40 extends only over the length L of the respective blade 6, does not extend over the circular end region d of the shaft 8. The purpose of this semicircular recess 40 is to create a space under the opening 40, as shown in Figure 1. Because of this space, the pressure plate 17 is supposed to be close up can be moved to the bottom sheet 6, so that the excavation path of the suction device 13 from the surface of the pressure plate 17 according to the double arrow 18 can only be very short (small stroke). In addition, the space according to the illustration in FIG. 1, in particular on the left side, is intended to enable the rotary movement of the pressure plate 17 with the sheet 6 fastened via the suction cups 13 according to arrow 27 to the bottom left.

If one takes a closer look at the cross-sectional view of the shaft 8 in FIG. 3, it can be seen that the inner plane 41 of the semicircular recess 40 does not open directly into the shoulder edge 37 in a radial extension. Rather, a nose 42 is formed between the shoulder 35 and the semicircular recess 40, which extends along the entire semicircular recess 40 and the upper side of which forms the contact surface 38 of the shoulder 35. The outer upper edge of this strip-shaped nose 42 is the already mentioned edge 39, which does not protrude beyond the outer contour of the circle of the shaft 8.

In the illustration in FIG. 4, the plane 41 appears next to the semicircular recess 40 as an invisible dashed line.

In operation, the suction device 13 is pivoted via the second drive 21, 24 with the pressure plate 17 withdrawn into the upper right position shown in solid lines in FIG. Thereafter, the first drive 19, 20 is actuated until the pressure plate 17 has moved upward from the position shown with solid lines to the extent that the piston rod 19 can be seen, which can only be seen in FIG. 1 in the position shown in broken lines as 19 '. Then the respective third drive 15, 16 is actuated so that the suction cups 13 can move up in the direction of arrow 18 up to the underside of the sheet 6 bent by the shafts 8.

From the straight state, in which the outer edges 37 of the lowermost sheets 6 come to rest on the respective shaft 8 at point X in FIG. 3, the sheet 6 is brought into the bent position in that the shaft 8 in the direction of the bent Arrow (Figure 3) 43 is moved so far that the rear edge 36 of the shoulder 35 extends slightly beyond the contact point X (the opposite shaft must rotate in phase in the opposite direction). Then the outer edge 37 of the sheet 6 falls into the shoulder 35. The rotation of the shaft 8 then stops and the rotational movement is switched over. In the opposite direction, the shaft 8 is then rotated, for example, to the position shown in FIGS. 1 and 3, where the rotary movement of the shaft 8 is stopped again.

Now the suction cups 13 grip the underside of the sheet 6, vacuum is applied, and the sheet 6 can be pulled out of engagement by the shoulders 35 of the two shafts 8 by pulling back the piston rod 15 by means of an air cylinder 16 and can be applied downward against the pressure plate 17.

Then the first drive is switched on again, the piston rods 19 pull the pressure plate radially back, reducing the turning radius. The second drive is then switched on by rotating the transport shaft 21 in the direction of the curved arrow 27 (FIG. 1) downward by about 90 ° so that the pressure plate assumes the dashed position. In this one can see the pressure plate 17 'with the sheet 6' held by the suction cups 13 '. The first drive has meanwhile been switched on, so that the piston rod 19 'is moved radially outward, so that the blade 6' comes into contact with the surface of the heated plate 28. The vacuum can now be applied via the nozzle openings 29 while the suction devices 13 'are being ventilated. At this moment, the sheet 6 'has been transferred to the heated plate 28, so that after pulling back the piston rod 19', the pressure plate 17 'can be pulled back to the short radius position after the "pressing" has been carried out and again according to arrow 27 in the can be pivoted back with solid lines position shown in Figure 1. The game then starts again.

Claims (7)

1. Device for separating sheets (6) of plastics, paperboard or the like stacked in a magazine (1), with at least one moveable suction means (13), and for transporting the separated sheets (6) to a workplace (28), wherein the sheets (6) are supported lying substantially horizontally in the stack (12) by means of supports (8) on the bottom edge (7) of the magazine, and between which the bottom sheet (6) lies freely and is accessible to the suction means (13), wherein along at least one of the two bottom edges (7) of the magazine (1) a rotary-driven shaft (8) is arranged as a support (8), characterised in that the shaft (8) is driven in an oscillating manner so that the bottom sheet (6) is brought into a downwardly curved position, the cross-section of the shaft (8) is recessed in the area of the length (L) of the sheet (6) forming a shoulder (35), the depth (t) of the shoulder (35) is equal to the thickness of the sheet (6) to be separated and that approximately in the centre between the edges (7) of the magazine (1) the suction means (13) is arranged so that it can be moved from below towards and away from the sheet.
2. Device according to claim 1, characterised in that the two supports opposite one another are configured as shafts (8) partly recessed in cross-section, which are synchronously driven with respect to one another in a rotating manner in opposite directions.
3. Device according to claim 1 or 2, characterised in that the shaft (8) has, in addition to the shoulder (35), a recess (40) with an approximately semi-circular cross-section.
4. Device according to one of claims 1 to 3, characterised in that between the shoulder (35) and the semi-circular recess (40), the shaft (8) is provided with a lug (42) extending tangentially within the cylindrically walled external surface of the shaft (8).
5. Device according to one of claims 1 to 4, characterised in that the suction means (13) is moveable in a translatory manner by means of a first drive (19, 20) and the first drive (19, 20) is fixed to a second drive (21, 24) for performing a rotary movement.
6. Device according to claim 5, characterised in that onto the first drive (19, 20) there is fixed a pressure plate (17) moveable in a translatory manner, on which the suction means (13) can be moved in a straight line by means of a third drive (15, 16) in the same direction (18) as the pressure plate (17).
7. Device according to one of claims 1 to 6, characterised in that at least one wall (7) of the magazine (1) is arranged to be displaceable perpendicular to the plane of the wall, for centring the stacked sheets (6; 12).

Images