DE19645265A1 - Device for mechanically separating workpieces that are connected lengthways - Google Patents

Abstract

The invention concerns a device for mechanically separating plastics workpieces (2) which are interconnected in train-like manner in a row via longitudinal seams, wherein the workpieces (2) are delivered, moved by holders relative to cutting devices, and then led away. According to the invention, in order to be able to design the seam projecting perpendicularly from the surface of a hollow body such that it is narrower yet be able to continue using the known production techniques, the holder holding the row of workpieces (2) can be adjusted parallel to at least one drive shaft (7, 8), and at least partially circular holder blades (9, 9') which have a groove on their periphery are secured on the drive shaft (7, 8) at a mutual spacing equal to the division of the row of workpieces (2) and can be brought into operational engagement with corresponding insertion blades (10, 10') disposed on the other side of the row of workpieces (2).

Description

The invention relates to a device for mechanical separation of strings in a row Workpieces of plastic joined together by longitudinal seams, in which the Workpieces fed, moved and removed relative to cutting devices by means of holders will.

From DE-A-43 05 913 it is known to use hollow bodies, in particular plastic packaging, to be produced in such a way that they are connected together in a row in a row via longitudinal seams. The known pack is centered in a plane parallel to the longitudinal central axis by a seam moved. On the one hand, this seam is production-related and, on the other hand, it stiffens the Pack. Nevertheless, the end user wants the seams to be as narrow as possible. During this seam can be accommodated in a molded-in depression in the base area, this exists Not possible for the two end faces protruding in the longitudinal direction at the front and rear. Rather, this seam protrudes vertically from these end faces or end walls by a few millimeters out. The width of these longitudinal seams cannot be reduced arbitrarily.  

When producing the aforementioned, known packaging, flat plates are made thermoformed plastic placed on a completely enclosed flat surface of a tool, in which depressions are arranged side by side such that half shells can be deep drawn. This way you can have several in a row produce interconnected hollow bodies, especially plastic packs, if one connects the half shells together. Two interconnected half shells then result a hollow body. This way, packs come in a series of two or four or eight or ten packs, which are connected to one another via webs. Form these webs later the longitudinal seams of the packs. The bars must be cooled and deep drawn need a minimum area. This later results in the longitudinal seams on the opposite ends of the respective pack with a width not to be undercut, which is also used to a small extent by the way, the half shell with the to connect others. Various proposals have been made, such as these strand-like Rows of hollow bodies can be separated, for example by separation welding, sawing or To cut. If you halve the connecting bridge between two packs, then each pack has a longitudinal seam that is too wide for the end user and that extends too far from the respective end surface protrudes in front and back.

Devices for the mechanical separation of such pack rows would, however, if you want to make narrower longitudinal seams, too complicated.

The object of the invention is therefore to so a device of the type mentioned improve that perpendicular from the surface of the workpiece, especially one Hollow body, protruding seam can be made narrower and still the well-known Manufacturing techniques can be maintained.

According to the invention, this object is achieved in that the row of workpieces receiving holder is adjustable parallel to at least one drive shaft on the drive shaft at a distance from each other equal to the division of the row of workpieces at least partially circular, on Scope of a groove-containing recording knife are attached, with corresponding, on the on the other side of the row of workpieces arranged insertable knives can be brought into active engagement. The arrangement of the workpiece row in a holder is known per se. This holder will as well have an elongated shape, like the row of workpieces, because the holder must be adapted to the row be. What is new is the arrangement of at least one drive shaft parallel to the holder and the Attachment of at least part-circular knives at an axial distance on this drive shaft such that the distance is equal to the division of the row of workpieces. This way comes each  a knife between two workpieces.

The knife, which is at least partially circular, has a groove on the circumference, so that it becomes a recording knife in the sense that a counter tool can be inserted into this groove can. Corresponding insert knives are now on the other side of the workpiece row arranged, which engage in the groove on the circumference of the receiving knife.

In this way, the invention provides two parallel cuts such that a strip is chip-like remains between the two cutting surfaces or is removed. This solution enables, for example, in the manufacture of hollow bodies, in particular plastic ver packs, the retention of the previous deep-drawing technology with the relatively wide Bridges between adjacent troughs because of the between two workpieces remaining wide web not halved by a single cut is relative with the result wider longitudinal seams, but because according to the invention two parallel and spaced apart running cuts are used to form two longitudinal seams of adjacent workpieces, so that there are narrow longitudinal seams and the excess material in between in shape a separated strip is led away.

This allows the seam to protrude from the surface of the workpiece approximately vertically can be made narrower by separating two workpieces from each other, and yet can the manufacturing process with the wide connecting bars for cooling and The attachment of the mold halves are retained together.

It is advantageous according to the invention if the distance is greater than the width of the one another workpieces to be separated and a second one of the same length parallel to the one drive shaft Drive shaft with a length slightly larger than the length of the row of work pieces rotatably driven is provided and at least equal to the division of the row of workpieces Partially circular insert knife having a cutting tongue on the circumference. At this In the embodiment, the row of workpieces passes between the two arranged parallel to one another Drive shafts. On one drive shaft the axial spacing is equal to the division of the Workpiece row attached a number of at least part-circular receiving knives, and There are a corresponding number on the side opposite the row of workpieces Insert knife on the other drive shaft and with the same pitch. This one pocket knives are also at least part circular and have a continuous circumference Cutting tongue, which fits into the circumferential groove of the receiving knife. This makes two work Shear forces between the cutting tongue of the insert knife and the groove of the receiving knife  together that a strip is cut out in between, which one simply takes away can. It is understood that the distance between the two arranged parallel to each other Drive shaft is large enough to hold the workpieces in between. The diameter the at least part-circular knife is then suitably large, so that the surfaces of the cutting tongue coming into active engagement with one another on the insert knife and the groove on the receiving knife come to rest in the middle area so that the Connecting web between the row-shaped workpieces is cut out without the workpieces are affected.

The cut can be made particularly cheap if the knife according to the invention are driven in opposite oscillating. Then it is enough from the respective circle of the knife (if you look at this from the side) to cut off a segment, which makes better Access conditions for attaching the knives to the drive shafts, etc. result. The The row of workpieces is spaced under the drive shafts and under the knife in the holder introduced, and this is then relative to the drive shafts between them to Example pushed upwards while the drive shafts turn the blades in Bring oscillatory movement so that the two cuts between two workpieces each can be placed continuously from top to bottom. The cut out strip becomes after the cut.

To increase the performance of packaging machines, workpieces are hollow and one-sided open plastic packages in rows of eight, ten or more hollow bodies in a row Thermoforming and sealing. In a series of ten packs there are then 9 To make double cuts. Each drive shaft then has nine receiving knives or Pocket knife with the consequence that with packs with volumes of 1-2 liter shafts with a Length over 1 meter and up to 1.50 meters must be used. Besides, has at packing manufacturers the wish arises, the production of 1 liter packs on 2 liter pack or generally switch from a first volume to a second volume. At larger packs, the distance between the drive shafts must be larger, and it must the diameter of the receiving and inserting knives also become larger. The hereby Resulting larger burdens and costs have led to considerations of their outcome represents a second solution such that the separating device according to the invention is characterized in that the distance is greater than the width of those to be separated Workpieces and parallel to the one drive shaft with a stationary knife carrier of the same length a length slightly greater than the length of the row of workpieces to which the Insert knives are attached, and that the drive shaft is driven continuously rotating.  

In connection with the first embodiment with the two drive shafts, each of which their series of at least part-circular knives was carried out, which is why the The distance between the drive shafts cannot be chosen arbitrarily large, with the result that you can not produce any size hollow body or workpieces. Now choose for this second embodiment with the stationary insert knives a first maximum width from workpieces to be machined, for example, packs with a volume of 4 liters of liquid, then the first teaching of the invention is the selection of the distance of the elongated knife carrier to the one drive shaft. It can be wide and narrow Workpieces are inserted into the space between the drive shaft and the knife carrier. While still the one drive shaft at an axial distance equal to the division of the Workpiece row at least part-circular receiving knife is located in the opposite knife carrier a corresponding number of pocket knives that are now are stationary attached to the stationary knife carrier. A stationary attachment is technically easier than a turned part. In addition, the knife holder is a stationary part better to design so that the distance between the drive shaft and the knife carrier can be greater than the distance between two drive shafts without functional disadvantages. A Another improvement is the continuous rotary drive for the single drive shaft compared to the oppositely oscillating drive mode of the first embodiment.

In addition, you can provide according to the invention that the drive shaft in the middle of it Longitudinal extension is driven. Even with a 1 meter or 1.50 meter drive shaft can avoid deflections and other tolerance-related inaccuracies because the drive from the center brings the wavelength in half. That in In the case of the second embodiment, circular recording knives can also be changed more easily when the drive shafts from the drive to their end are shorter, and so can other assembly changes can be made more easily.

In an advantageous further embodiment of the invention protrudes into the groove of the respective rotatable Pick-up knife from the rear, opposite the insertion knife a stationary ejector squeegee. This squeegee is as thin as the cutting tongue of the Insert knife and protrudes from outside into the groove of the receiving knife, which is still there can turn. The groove therefore has a depth of about a quarter to a half of the radius of the circular recording knife. It projects in a crescent shape over about half the circumference of one side outside to the opposite side (inside next to the cutting point). Radial the ejector blade has a partially rounded surface (preferably in the area of the Recording knife round) guide surface in the area of the circular  Recording knife at a distance of about 1-10 mm, preferably 2-5 mm, from the outside The scope of the recording knife runs. This can be a cut out plastic strip be held by the groove of the receiving knife and with the rotary movement of the knife hike with him until he hits the guide surface and radially outwards and backwards is brought out. In the rear area, the guide surface of the ejector blade can be straight. This rear guide surface is preferably set at approximately 45 ° against the perpendicular, and a waste container is preferably located below and behind it. The cut out Stripes or chips then fall into the after leaving the guide surface of the ejector knife Waste bin.

As explained above, the stationary insert knife is located in the area of the cutting point. According to the invention, this is characterized in that it is a clamped flat knife with a partially curved blade, to which a hard metal insert is preferably attached. The knife carrier is preferably executed for the circular receiving knife Fastening cheeks, between which or on which the insert knife in the form of a flat Sheet is clamped and screwed tight. The narrow side facing the cutting point or narrow edge of the insert knife is curved and enters the cutting area wear-free and rustproof hard metal, in particular a Widia insert, which is like a Cutting tongue with the foremost area of the curved blade in the groove of the receptacle sers protrudes. There is the active intervention with the receiving knife and the cutting area.

The device according to the invention is suitable for separating hollow bodies thermoformed plastic, especially of plastic packaging. The thermoformable Plastic material for such a package can be a thermoplastic, for Example polypropene. PVC can also serve as such plastic, with polypropene in the Technology is also largely known as polypropylene. These packs consist of perfectly reworkable and easily rotten parts and materials. You can do that Also fill plastic material, using as fillers here on chalk, mica, talc, plaster or the like is thought. In practice, filling levels of up to 70%, preferably 60%, proven to be cheap. Such filled plastic materials can therefore be reprocessed or can be recycled and have the properties of a plastic, in particular deep-drawable and also sealable.

Further features, advantages and properties of the present invention result from the following description in conjunction with the accompanying drawings, which preferred Illustrate embodiments of the invention. Show it:  

Fig canceled. 1, the cross-sectional view of a first embodiment with two drive shafts and at intervals in pairs on this recording and arranged Einsteckmessern,

Fig. 2 is a sectional view through two drive shafts with a pair of knives according to the first embodiment of FIG. 1, but without the workpieces,

Fig. 3, the partially broken away cross-sectional view of a second embodiment wherein the Einsteckmesser is stationary, with the right arranged next to waste container,

Fig. 4 is a plan view of the device of FIG. 3, cut in the middle, and

Fig. 5 is an enlarged partial view of the second embodiment according to FIGS. 3 and 4, wherein the wiper blade is particularly illustrative light instead of the central drive.

In Fig. 1 is seen in plan view of strand-like manner in a series of longitudinal seams 1 interconnected workpieces 2 in the form of packs that have above a pour opening 3, in which one vertically from top to bottom in Fig. 1 in looks. This viewing direction is parallel to the longitudinal direction of the pack 2 , the opposite side walls 4 , 5 of which are each crossed by the longitudinal seam 1 , which can be seen as a vertical, bold line in FIGS. 3 and 5. To explain the two embodiments described here, reference is made to a hollow body, namely the workpiece 2 in the form of a liquid pack.

For the sake of simplicity, the holder 6 for accommodating both the packs 2 which are still attached to one another and the packs which have been separated after processing is omitted in FIGS. 1 and 2 and is only shown in connection with the second embodiment according to FIGS. 3 to 5.

In the first embodiment according to FIGS. 1 and 2, the row of packings connected to one another via the longitudinal seams 1 (or their holder, not shown) is parallel to two drive shafts 7 and 8 , whose (clear, ie smallest) distance from one another is greater than that Width B of the pack 2 must be such that both the row of packs and, after separating, the respective pack can be guided in its longitudinal direction through the space between the drive shafts 7 and 8 .

Both the shaft 7 and the shaft 8 carry knives 9 , 10 and 9 ', 10 '. In the axial direction of the drive shaft 7 are rotationally fixed on their part-circular receiving knife 9 , 9 'at an axial distance from one another, which is equal to the division of the pack row 2 in the sense that the outer circumference 11 of the receiving knife 9 , 9 ' tapered towards the circumference in each case fits between two successive packs 2 and there can come into engagement with the longitudinal seam 1 connecting these packs 2 .

In the same way, part-circular insert knives 10 , 10 'are also mounted on the second drive shaft 8 in a rotationally fixed manner, which likewise taper towards their circumference 12 . In the same way as described above in connection with the receiving knife 9 , 9 ', the insert knife 10 , 10 ' are attached to the drive shaft 8 at a distance equal to the division of the pack row.

From the cross sectional view of Fig. 1 to 10 detects the cutting tongue 13 of the respective Einsteckmessers 10 'which, 9 in the groove 14 in the receiving knife 9' is immersed.

The knives 9 , 10 of the first embodiment according to FIGS. 1 and 2 are driven oscillating in opposite directions and work, while the row of packs 2 on the holder are pushed upwards, for example, from below between the drive shafts 7 and 8 . By immersing the cutting tongue 13 on the circumference 12 of the inserting knife 10, a double cut is created which is such that it allows a longitudinal seam 1 to protrude from the front and rear surface of the pack 2 , but only by a very small distance of 0.5 -3 mm, preferably 2 mm, while a strip of the thickness of the cutting tongue 13 between the successive longitudinal seams 1 is cut off and removed.

The second embodiment is shown in FIGS. 3 to 5 and does not have two but only one drive shaft 8 . At a distance greater than the width B of the packs 2 , an approximately equally long, stationary knife carrier 15 , which is illustrated in FIG. 4, extends parallel to the drive shaft 8 , on the left in FIGS . 3 and 5 and in FIG. 4, while it is omitted for simplicity in FIGS. 3 and 5. But you can see the stationary insert knife 10 a, which is inclined at about 40-50 ° against the vertical. Its front edge faces the circular recording knife 9 . This front edge is hidden in the figures, but one can see the hard metal insert 16 made of Widia steel, which is part of the front edge, which is preferably curved upward, and projects as a cutting tongue 13 into the groove 14 of the receiving knife 9 . The receiving knife 9 is continuously rotatably driven in the direction of the curved arrow 17 , while the insert knife 10 a is stationary.

Similar to the long drive shafts 7 and 8 of the first embodiment, the drive shaft 8 of the second embodiment is so long that it extends over all, for example seven stations, along eight packs 2 arranged in a row. In Fig. 4, a sectional view taken approximately along the dash-dotted line IV-IV in Fig. 3, you can see through the demolition only the first and last station, ie the first and last recording knife 9 , which is opposed by a stationary insert knife 10 a.

In Fig. 4 in the central region, the designated 18 midway along the length of the drive shaft 8 is shown. The drive shaft thus extends in one piece only over five or four or three stations if ten, nine or a similar number of packs in a row are to be separated at the same time. The deflection of the drive shaft 8 is therefore considerably less.

The depth of penetration of the cutting tongue 13 into the groove 14 of the knives 9 , 10 is approximately 2 mm, and this for both embodiments.

The drive takes place via the motor 20 flanged at 19 via a worm 21 and a worm wheel 22 , which is attached to the drive shaft 8 in a rotationally fixed manner, like the receiving knife 9 .

If one considers the cutting area of the receiving knife 9 where the cutting tongue 13 projects into the groove 14 of the receiving knife 9 as the front side, then there is a fastening rod 23 on the side opposite the insert knife 10 a (with respect to the receiving knife 9 ), on which means Plastic reinforcements 24 an ejector 26 is rotatably attached via screw connections 25 . Its front end, shown on the left in FIG. 5, grips more than half of the drive shaft 8 in a crescent shape and lies in the deeply cut groove 14 of the receiving knife 9 . The rear end is straight and on the plastic reinforcements 24 on the rod 23 rotatably held. The plastic reinforcement 24 is kept so wide that the chip or the cut strip of plastic is guided and will surely find a support surface when it is discharged backwards and downwards in the direction of arrow 27 into the waste container 28 .

In operation, the row of, for example, eight packs 2 in a row is introduced via a holder 6 under the cutting area parallel to the drive shaft 8 , so that the web connecting the packs 2 or their longitudinal seam 1 comes to lie in the cutting area when the packs 2 are promoted vertically upwards. The cutting area is the area of engagement of the cutting tongue 13 or the widia insert 16 in the groove 14 of the receiving knife 9 . In the second embodiment according to FIGS. 3 to 5, the receiving knife 17 is set in a circular shape in a continuous rotation according to the curved arrow 17 .

Then the packs 2 are pushed over the holder 6 upwards, so that each stationary insert knife 10 a begins to cut out a strip which is shown in FIG. 5 with a thick dash-dotted line and is designated by 29 . This strip consists of the same material as the pack 2 and represents the waste to be discharged. Although the dash-dotted line 29 is shown somewhat long in FIG. 5, one must of course think of the cut-out strip as long as the longitudinal seam 1 of the pack 2 . In Fig. 5 the path of the strip during its removal is to be illustrated. At the upper end corner of the widia insert 16 , the strip is cut out and clamped in the groove 14 of the receiving knife 9 . It lies loosely clamped in the groove and moves up and to the right in an arc. It lies on the curved outer surface 30 of the ejector knife 26 and is guided in an arc around the drive shaft 8 to the right at a distance from its axis, namely on the surface 30 . Because the ejection squeegee 26 becomes straight in the upper right quadrant, the strip or chip 29 made of plastic then also moves downward in the direction of the arrow 27 on the straight surface 30 of the squeegee 26 . It is, so to speak, lifted out of the circular groove 14 of the receiving knife 9 and - partly also via the plastic reinforcements 24 - guided down into the waste container 28 .

Claims (8)

1. Device for the mechanical separation of strands in a row over longitudinal seams ( 1 ) interconnected workpieces ( 2 ) made of plastic, in which the workpieces ( 2 ) are fed, moved and removed relative to cutting devices by means of holders ( 6 ), characterized that the holder ( 6 ) receiving the row of workpieces ( 2 ) can be adjusted parallel to at least one drive shaft ( 7 , 8 ) on the drive shaft ( 7 , 8 ) at a distance from one another equal to the division of the row of workpieces ( 2 ) at least in part-circular fashion on the circumference a groove ( 14 ) having receiving knives ( 9 , 9 ') are fastened, which can be brought into operative engagement with appropriate speaking, on the other side of the workpiece row ( 2 ) arranged inserting knives ( 10 , 10 '; 10 a). 2. Device according to claim 1, characterized in that at a distance greater than the width (B) of the workpieces to be separated ( 2 ) and parallel to the one drive shaft ( 7 ) a second, approximately equally long drive shaft ( 8 ) with a length slightly larger than the length of the row of workpieces ( 2 ) is provided in a rotatably driven manner and at a distance from each other equal to the division of the row of workpieces ( 2 ) has at least part-circular insert knives ( 10 , 10 ') which have a cutting tongue ( 13 ) on the circumference. 3. Apparatus according to claim 1 or 2, characterized in that the knives ( 9 , 10 ) are driven oscillating in opposite directions. 4. The device according to claim 1, characterized in that at a distance greater than the width (B) of the workpieces to be separated ( 2 ) and parallel to the one drive shaft ( 8 ) an equally long, approximately stationary knife carrier ( 15 ) with a length is attached somewhat larger than the length of the row of workpieces, on which the insert blades ( 10 a) are attached, and that the drive shaft ( 8 ) is driven continuously rotating. 5. The device according to claim 4, characterized in that the drive shaft ( 8 ) is driven in the middle ( 18 ) of its longitudinal extent. 6. Device according to one of claims 1 to 5, characterized in that in the groove ( 14 ) of the respective rotatable pick-up knife ( 9 ) from the rear, a plug-in knife ( 10 a) opposite side in each case a stationary From squeegee ( 26 ) protrudes into it. 7. Device according to one of claims 4 to 6, characterized in that the insert knife ( 10 a) is a clamped flat knife with a partially curved blade, to which a hard metal insert ( 16 ) is preferably attached. 8. Use of the device according to one of claims 1 to 7 for separating hollow bodies made of thermoformable plastic, in particular of plasticizer packs ( 2 ).