EP0015392B1 - Advancing device with a diverter for sheet-like materials - Google Patents

Description

The invention relates to a conveyor device with a switch according to the preamble of claim 1.

From DE-B-25 59 138 a device is known in which the switch is designed as a pivotable tongue around one end and can optionally be adjusted to one of the inputs of two further conveyors, so that a workpiece supplied to the switch can either be one or the second conveyor can be fed.

Devices of this type are used to subdivide a sequence of workpieces, in particular of bags produced in succession in a bag welding machine, by alternately feeding these workpieces to the two further conveyors into two workpiece sequences, in which case the distances between the successive workpieces are greater than a workpiece length, so that the conveying speed of the workpieces can be significantly reduced by reducing these distances. This is particularly important if the film-shaped objects are to be stacked into flat stacks.

If a rapid sequence of sheet-shaped workpieces, e.g. of thermoplastic bags welded in a welding machine, then the individual workpieces are thrown against a stop at a relatively high speed during stacking and are suddenly braked as a result. Due to the sudden braking, the rear parts of the workpiece slide over the front, so that a perfect stacking at high conveyor speeds of the film-shaped workpieces is not possible.

Here, the known switches provide a remedy, since the conveying speed of the film-shaped workpieces in the two further conveyors can thereby be significantly reduced, and this enables perfect stacking even in the case of rapid sequences of the film-shaped workpieces in the first conveyor.

However, the known switches which work with a tongue which can be swiveled up and down are not suitable for deflecting workpieces which are fed in very quickly in succession, since the operation of the switches causes increasing difficulties with increasing frequency of the workpiece sequence.

DE-A 27 25 546 discloses a device of the type mentioned at the outset, which is used to selectively eject selected sheets of paper from a series of sheets of paper lying very closely behind one another by deflecting them. After an interruption, the paper sheets that have not been discharged are fed to a second conveyor formed by transport belts. However, this is only possible with film-shaped workpieces that have a certain inherent rigidity like paper. On the other hand, if you want an unstiff material, e.g. Transport bags made of thermoplastic material in a rapid sequence, then there is the risk that in the interruption mentioned between the device mentioned at the beginning and the second conveyor formed by the transport belt, the bags lose the intended path and this leads to malfunctions.

The invention is based on the object of designing the conveyor device of the type mentioned at the outset in such a way that it can also be used for film-shaped workpieces made of a completely stiff material, e.g. also for thermoplastic bags.

This object is achieved by the features mentioned in the characterizing part of claim 1.

The fact that, according to the invention, each sheet running through the switch is always guided by a guide body, it is achieved that when a sequence of workpieces which, like bags made of thermoplastic plastic, have no inherent rigidity at all, is transported in two sequences after passing through the switch can be done without having to interrupt the guidance of the workpieces for one of the two sequences. The invention therefore makes it possible for the first time to deflect workpieces without inherent rigidity in a switch without mechanical means very quickly and easily in two sequences, the thickness of the film-shaped workpieces being irrelevant and also e.g. Plastic bags made of extremely thin material can be conveyed through the switch and alternately safely guided to two second conveyors.

In an advantageous embodiment, the switch is connected downstream of a welding machine with a continuously rotating welding bar for producing bags made of thermoplastic material. It is provided that the rotational frequency of the guide body is synchronized with the rotational frequency of the welding bar. The circulation phase of the guide body can be adapted to the conveying phase of the first conveyor so that the front edge of each workpiece alternately touches the circumferential surface of one or the other guide body in the perforated area and is accordingly sucked in and deflected accordingly.

Rotational bodies such as rollers or disks can be provided as guide bodies.

In an advantageous embodiment, the guide bodies are designed as tapes according to claim 2, for example according to claim 4 as toothed belts or toothed belts which, as a result of the toothing, the belt always assumes a precisely defined position relative to the toothed pulley which redirects it, so that suction holes can be provided in such a toothed belt-shaped guide body, which only coincide with a suction hole in the toothed disk when the leading edge of a film-shaped workpiece touches the tape in the area of its suction hole.

In the guide device mentioned at the outset, known from DE-OS 27 25 546, the paper sheets are deflected during the selective discharge by a roller serving as a guide body with suction bores and are guided by conveyor belts for which annular grooves are embedded in the outer surface of the roller, in which the Bands are guided between the mouths of the suction holes. However, the production of rolls with such ring grooves is relatively expensive. The use of toothed belts provided with suction holes according to the invention also has the disadvantage that these are relatively expensive components and are only commercially available in certain specified length gradations with relatively short maximum lengths, so that, in addition to increasing the cost of production and operating costs, this also limits the design options are.

Through the embodiment of the invention claimed in claim 15, expensive rollers or toothed belts can be avoided. Air-permeable tapes are available in a wide variety of embodiments, for example in the form of fabric tapes or belt-like structures provided with perforation holes. An annular groove is not required for the deflection of such a band in a roller used for deflection, so that the roller serving as deflection body can be used in its simplest form with a smooth surface. The conveyor belt now does not have to assume a defined position with respect to the deflection body because of the air-permeable region which extends over the entire length of the conveyor belt. Air-permeable conveyor belts are also considerably cheaper than the toothed belts mentioned above and are available in any lengths so that they do not limit the design options of the conveyor device. By means of a phase control it can be achieved very easily that the desired film-shaped workpiece is sucked with its front edge in the switch from the suction hole of the deflecting body through the air-permeable area to the conveyor belt and thereby deflected. If the distance between the leading edges of the successive workpieces is the same or a multiple of the circumference of the deflecting roller, then either workpiece is deflected or any selected workpiece can be deflected by controlling the negative pressure within the deflecting roller. If, on the other hand, the circumference of the deflecting roller is dimensioned twice as large as the distance between the leading edges of two adjacent workpieces fed to the switch, every second workpiece is advantageously deflected. When controlling the device according to the invention, it is therefore expedient to provide that the distance between the leading edges of the workpieces following one another in the first conveyor and the length of the circumference of the cylindrical deflecting body are in a relationship to one another in which the one size is an integral multiple of other is.

The invention is explained in detail in the following description of exemplary embodiments shown schematically in a highly simplified manner in the drawing, with two deflecting devices of the switch acting in opposite directions.

• Fig. 1 eine Seitenansicht des Ausführungsbeispieles;
• Fig. 2 eine perspektivische Teilansicht auf die untere Umlenkeinrichtung der Weiche des Ausführungsbeispieles nach Fig. 1;
• Fig. 3 eine Draufsicht der unteren Umlenkeinrichtung und des dieser nachgeschalteten weiteren Förderers;
• Fig. 4 eine teilweise im Vertikalschnitt dargestellte Seitenansicht einer Zahnbandscheibe der unteren Umlenkeinrichtung;
• Fig. 5 einen Teil-Axialschnitt durch mehrere koaxial angeordnete Zahnbandscheiben, der die Verbindung der Ansauglöcher in den Zahnbändern mit einem Ansaugkanal zeigt, und
• Fig. 6 eine der Fig. 1 entsprechende Darstellung eines zweiten Ausführungsbeispieles.

Show it:

• Fig. 1 is a side view of the embodiment;
• FIG. 2 shows a partial perspective view of the lower deflection device of the switch of the exemplary embodiment according to FIG. 1;
• 3 shows a plan view of the lower deflection device and of the further conveyor connected downstream thereof;
• 4 shows a side view, partially in vertical section, of a toothed disc of the lower deflection device;
• Fig. 5 is a partial axial section through several coaxially arranged toothed belt disks, which shows the connection of the suction holes in the toothed belts with an intake duct, and
• Fig. 6 is a representation corresponding to Fig. 1 of a second embodiment.

The exemplary embodiment of a conveyor device for film-shaped workpieces shown in the drawing has a switch 301 which consists of a lower deflection device 301 a and an upper deflection device 301 b and which is designated by a bag welding machine, designated as a whole by 302 and indicated only schematically in FIG. 1 manufactured bags 20 made of thermoplastic plastic are supplied in rapid succession. By means of the two deflection devices 301 and 301b, these bags 20 are alternately fed to two further conveyors 303a and 303b, which the bags 20 each have a stacking place 306a or 306b by means of pulley arrangements 304a or 304b known for this purpose and also known brake shaft pairs 305a or 305b feed where the bags 20 are stacked into flat stacks.

The bag sealing machine 302 can be designed in any known manner. However, the exemplary embodiment of a conveyor device for plastic bags described here is particularly suitable for welding machines, who manufacture bags with a very high frequency. Bag welding machines of this type work with a welding tool that rotates continuously but preferably with a non-uniform and adjustable peripheral speed. Such high-performance bag welding machines are known, for example, from DE-PS 14 79 807 and described in the unpublished DE-OS 28 10 204, 28 10 127 and 28 46 220. However, the conveying device described here can also be used with the less efficient bag-making machines which work with a sealing strip which can be moved up and down and with a film web fed in batches.

The welding machine 302 shown in FIG. 1 has two feed rollers 11 and 12 and a continuously but non-uniformly rotating welding roller 15 which interacts with a counter roller 17. Through the feed rollers 11 and 12 forming a conveying gap, a longitudinally slotted, tubular, thermoplastic film web 10 is fed to a welding gap between the welding roller 15 and the counter roller 17. The welding roller 15 has a welding tool 16 which, when the welding roller 15 rotates in the direction of the arrow 18 shown in the drawing, together with the counter-roller 17 which also rotates in the opposite direction in the direction of the arrow 19 shown in the drawing, performs a separation welding in which a bag 20 separated from the film web 10 and at the same time a side seam trailing in the conveying direction is formed on the bag 20 and a seam on the front edge of the tubular film web 10, which forms a leading side seam in the next bag.

Each of the two deflection devices 301 a and 301 b has a plurality of toothed belts 307a and 307b, which run side by side in parallel vertical planes (FIGS. 1, 2 and 3), of which each toothed belt 307a and 307b for circulation in the direction of arrow 311 a and 311 b on three toothed belt disks 308a, 309a and 310a or 308b, 309b and 31 Whether it is mounted such that each of the toothed belts 307a rotates in the same vertical plane as a corresponding toothed belt 307b.

The toothed belt disks with the same reference number are arranged coaxially, so that the toothed belts 307a on the one hand and 307b on the other hand overlap in the direction perpendicular to their plane of rotation. The upper run of each toothed belt 307a touches the lower run of each toothed belt 307b in a horizontal plane, so that the upper runs of the toothed belts 307a form a horizontal conveying gap 312 for the bags 20 with the lower runs of the toothed belts 307b (FIG. 1).

The axes 313a and 313b of the adjacent toothed discs 308a and 308b located at the exit of the switch 301 are arranged parallel to one another in a plane which forms an angle a of less than 90 ° with the horizontal plane of the conveyor gap 312 of the switch. As a result, the clear distance between the toothed belt disks 308a and 308b, which is required in the case of disks arranged vertically one above the other for touching the toothed belt strands in the conveying gap 312, can be increased by a factor of 1 / sin a to compensate for fluctuations in the thickness of the toothed belts without the contact increasing the tooth belt dreams changes.

The distance between the toothed belt disks 310b and the toothed belt disks 308b is smaller than the distance between the toothed belt disks 310a and the toothed belt disks 308a, so that the conveyor gap 312 only begins at a distance from the output of the welding machine 302. To bridge this distance, round belts 315 are provided in the spaces between the toothed belts 307b, which run around round pulleys 316 at the end on the left in FIG. 1 and around rollers 317 and 318 at the end on the right in FIG. 1, in which grooves for the round belts 315 are provided. These rollers 317 and 318 extend over the entire width of the switch 301 and are rotatably supported at their ends in levers 319, the ends of which are remote from the rollers 317 and 318 and are pivotable about a common axis 321 in the machine frame, of which in FIG. 3 and 5 only walls 320 and 343 are shown. With these levers, one end of crank rods 322 are pivotally connected, the other ends of which are pivotally connected to crank disks 323. Between the round belt pulleys 316, on the one hand, and the round belt rollers 317 and 318, on the other hand, there is a roller 324, which extends over the entire width of the switch 301, the underside of which rests on the lower strands of the round belts 315 and is rotatable with its two ends and parallel to the conveyor gap 312 is adjustable in the machine frame. The round belts 315 and the toothed belt discs 307a form an inlet gap upstream of the conveyor gap 312, which gap opens and closes continuously when the crank discs 323 rotate. The crank disks 323 are coupled to the drive of the welding roller 15 in such a way that each time a welding is completed by the welding tool 16, the inlet gap closes and the separated bag 20, the leading edge of which has entered the opened inlet gap 325, in the inlet gap 325 clamped and is conveyed into the conveyor gap 312 by the toothed belts 307a and round belts 315 rotating at the same peripheral speed.

The two further conveyors 303a and 303b are symmetrical in relation to the plane of the conveying gap 312, so that the description of one conveyer 303a is sufficient to also explain the construction of the second conveyer 303b.

The conveyor 303a has a number of conveyor belts 326a corresponding to the number of toothed belts 307a, of which each conveyor belt 326a is mounted on conveyor belt disks 327a, 328a and 329a in such a way that the conveyor belt strand which extends between the conveyor belt disks 327a and 328a bears against the adjacent toothed belt 307a and forms a conveyor gap 330a therewith. A number of the coaxial conveyor discs, e.g. the conveyor belt disks 328a is driven so that the conveyor belts 326a rotate in the direction of arrow 331a at the same peripheral speed as the toothed belts 307a.

Each conveyor belt 326a is assigned a conveyor belt 332a, which rotates around two conveyor belt disks 333a and 334a. The conveyor belt disks 333a on the one hand and the conveyor belt disks 334a on the other hand are each mounted on common axes which are arranged such that the upper runs of the conveyor belts 332a abut against the runs of the conveyor belts 326a extending between the conveyor belt disks 328a and 329a and thereby form a conveyor gap 335a.

In order to deflect a bag gripped by the conveyor gap 330a into the conveyor gap 335a, round belts 336a are provided in the connected spaces between the toothed belts 307a and the conveyor belts 326a and 332a, which are on round belt pulleys 337a (FIGS. 3 and 5), 338a, 339a and 341 a are guided in such a way that, together with the conveyor belts 326a, they deflect the bags from the conveyor gap 330a into the conveyor gap 335a, as can be seen in particular from FIG. 1.

The corresponding parts of the further conveyor 303b are designated in the drawing with the same reference numbers, only that the letter a is replaced by the letter b there.

The toothed belt pulleys 308a and 308b are fastened together with the round belt pulleys 337a and corresponding round belt pulleys of the deflection device 301b to hollow shafts 342a (FIG. 5), 342b which are rotatably mounted in the side walls 320 and 343 of the machine frame. The cavity 340 of the hollow shaft 342a is connected to a suction fan 345 via a hose 344a. For this purpose, the hose 344a is connected to a suction air connector 346a, which is rotatably mounted on the open end of the hollow shaft 342a by means of a grooved ball bearing 347a sealed on both sides, so that a rotary connection connecting the hose 344a to the rotatable shaft 342a is thereby formed. Correspondingly, the cavity of the hollow shaft 342b (FIG. 2) carrying the toothed belt pulleys 308b and the round belt pulleys 337b is connected to the suction blower 345 via a hose 344b.

In the outer circumference of the hollow shaft 342a, an axial groove 348 for feather keys 349 is provided, by means of which the toothed belt disks 308a attached to the hollow shaft are connected in a rotationally fixed manner to the hollow shaft. Spacer rings 351 are arranged on the hollow shaft between the toothed belt disks 308a, on which the round belt pulleys 337a sit, which are clamped between the toothed belt disks 308a by means of screw nuts 352.

Each toothed disc 308a is provided with an annular groove 353 in the wall of its central bore. Furthermore, each toothed disc 307a has ten radial bores 354, which are arranged in pairs in diametrical planes such that their outer ends in the head surface 355 of adjacent teeth 356 and their inner ends open into the annular groove 353. The bore openings 357 in the top surface of the teeth 356 are widened over the cross section of the radial bores 354 at least in the tooth width direction, on all sides in the exemplary embodiment shown. The number of pairs of radial bores 354 is selected such that the rows of bore openings extending in the circumferential direction of the toothed intervertebral disc extend over a section of the toothed intervertebral disc circumference which is approximately as long as the length of the section of the toothed intervertebral disc circumference wrapped by the associated toothed belt 307a, as can be seen from Fig. 4. Bores 350 are provided in both hollow shafts 342a and 342b for connecting the annular grooves 353 to the cavities 340.

In each toothed belt 307a several, in the illustrated embodiment three groups 362a, of suction holes 358 arranged in adjacent valley bottoms 359 between two teeth 361 are arranged such that, with a corresponding arrangement of the toothed belt 307a on the toothed disk 308a, the suction holes 358 with the mouths 357 of the radial bores 354 ceilings. The adjacent groups 362a of the suction holes 358 are arranged in such a way that there are twice as many teeth 361 between the suction holes covering the same pairs of bore openings 357 when the toothed belt 307a rotates as the toothed disc 308a.

In exactly the same way, the toothed belt disks 308b are connected to their hollow shaft and also have radial bores 354, the mouths of which coincide with suction holes 358 when the toothed belts 307b rotate. However, since the toothed belts 307b are shorter than the toothed belts 307a, only two groups 362b of suction bores 358 are provided in the toothed belts 307b in the exemplary embodiment shown.

The toothed belt discs 308a and 308b have a circumference through which the tooth rotates with each rotation of the toothed belt discs belts 307a and 307b are moved a distance which is as long as the width of the widest bag measured in the conveying direction 311c, b. As a result, the front edge of each bag fed through the conveyor gap 312 to the outlet of the switch 301 is always opposite the same segment of the toothed belt disks 308a and 308b.

The toothed belt disks 308a and 308b are fastened to the hollow shafts in such a phase relationship that the outer ends of the radial bores 354 are always symmetrical to the plane of the conveying gap 312 and thus always at the same time and in the same assignment at the turnout exit as in FIG. 1 is shown.

The hollow shaft 342a, like the hollow shaft 342b carrying the toothed belt disks 308b, is driven with the same number of revolutions in the unit of time as the welding roller 15. The toothed belt disks 308a and 308b here have the same diameter, which is however so large that the one revolution of the toothed belt discs 308a and 308b causes a bag to be slightly larger than the feed of the material web 10 caused during one revolution of the welding roller 15. The round belt pulley 316 is also driven accordingly in order to generate the same feed speed for the round belts 315. It is thereby achieved that the bags 20 ejected by the welding machine 302 are moved at a somewhat higher feed rate than the material web 10, so that a proper separation of each new bag from the material web 10 is thereby ensured.

The hollow shaft 342a is driven by a phase adjustment gear 364. For this purpose, a differential gear or preferably a gear known from the Harmonic Drive System GmbH company known as "HARMONIC DRIVE differential gear". be used. The phase position adjustment gear 364 is provided with a handle 365, by means of which the phase position of the toothed disc 308a can be set without changing the speed. The hollow shaft 342a is connected to the hollow shaft 342b via two gearwheels 366 and 367, so that it is driven at the same speed, but with the opposite direction of rotation, as the hollow shaft 342a. The toothed belts 307a and 307b are arranged on their toothed belt disks 308a and 308b; that whenever the bore mouths 357 of the toothed belt discs 308a coincide with the suction holes 358 of the toothed belt 307a, the bore mouths 357 of the toothed belt discs 308b are covered by sections of the toothed belt 307b which are not provided with suction holes. This is possible because there are twice as many teeth 361 as the number of teeth 361 between the corresponding bore openings 357 of both the toothed belts 307a and the toothed belts 307b, so that the bore openings 357 of each toothed intervertebral disc 308a and 308b are adjacent to the suction holes 358 Only cover groups 362a and 362b after every second rotation of each toothed disc 308a and 308b.

The operation of the embodiment is explained below with reference to FIG. 1.

Through the feed rollers 11 and 12, the material web 10 is inserted into the gap between the welding roller 15 and the counter roller 17. As long as the welding tool 16 is not yet in the welding position, the inlet gap 325 is open. At the moment when the welding tool 16 separates a bag 20 from the continuously supplied material web 10 by welding, the inlet gap 325 closes, so that the bag is clamped between the toothed belts 307a and the round belt 315 and is slightly larger in the conveyor gap 312 Speed is introduced as the speed of the material web 10. During operation of the machine, the suction fan 345 is continuously in operation, so that the radial bores 354 of all toothed discs 308a and 308b are always connected to the cavity 340 of the hollow shafts 342a and 342b, which is under vacuum. By the phase adjustment 364 (Fig. 2), the phase position of the toothed discs 308a and thus automatically the toothed discs 308b is set so that whenever the front edge of a bag 20 gets into the space between the toothed discs 308a on the one hand and 308b on the other hand, either that Suction holes 358 of the toothed belts 307a or the suction holes 358 of the toothed belts 307b are located in the region of the front edge of the bag. Since the suction holes 358 of each toothed belt 307a or 307b then coincide with the corresponding bore mouth 357 of the radio bores 354 when they touch the circumference of the corresponding toothed belt disc 308a or 308b, the front edge of the bag is sucked onto the corresponding toothed belt 307a or 307b and thereby held on the toothed belt until the front edge of the bag either gets into the conveyor gap 330a or 330b, from where it is then inserted into the conveyor gap 335a by means of the round belts 336a or 336b, from which it then passes over the pulley arrangement 304a to the brake shaft pair 305a or 305b is supplied. Since the arrangement of the groups 362a and 361b of the suction holes 358 in the toothed belts 307a and 307b of the two different deflection devices 301a and 301b always alternately feeds the one bag to the further conveyor 303a and 303b, there is between the successive ones Bags in the further conveyors 303a and 303b are always at a distance corresponding to at least one bag length, so that the bags can now be braked strongly by the brake shaft pair 305a or 305b before being introduced into the stacking place 306a or 306b.

The embodiment described above and shown in the drawing represents a preferred embodiment. However, the invention can also be carried out in many modifications. For example, to achieve the same purpose, it is sufficient to provide only the deflection device 301 b, which then deflects every second bag from the straight path of the conveyor gap 312. The conveyor gap could in this case be formed by providing conventional conveyor belts instead of the toothed belts 307a, which extend in the plane of the conveyor gap 312 beyond the deflection device 301b and there, with the lower runs of conveyor belts arranged above them, in the manner of the conveyor gaps 335a Form conveyor gap.

Another possible modification is that deflection rollers are provided as deflection bodies instead of toothed belts 307a and 307b. However, these deflection rollers would then have to have a diameter at least twice as large as that of the toothed belt discs 308a and 308b.

In the preferred embodiment, ten suction holes are provided. Depending on the size of the bags, more or fewer suction holes can be provided, e.g. it may be sufficient in some cases if there is only one suction hole for sucking the front edge of the bag.

The exemplary embodiment of a conveyor device for film-shaped workpieces shown in FIG. 6 has a switch 301 which consists of a lower deflection device 301 and an upper deflection device 301 b and which is designated by a bag welding machine, designated as a whole by 302 and indicated only schematically in FIG. 6 manufactured bags 20 made of thermoplastic plastic are supplied in rapid succession. By means of the two deflection devices 301 a and 301 b, these bags 20 are fed alternately via two further conveyors 303a and 303b to a union point 401, in which two bags are placed one against the other in an aligned position, which will be explained in more detail below. From the union point 401, the pairs of bags are then fed via a pulley arrangement 304 known for this purpose and a brake shaft pair 305, also known, to a stacking station, where the bags 20 are stacked into flat stacks.

The loot welding machine 302 can be designed in any known manner. However, the exemplary embodiment of a conveyor device for plastic bags described here is particularly suitable for welding machines which produce bags at a very high frequency and which work with a welding tool 16 which rotates continuously but preferably with a non-uniform and adjustable peripheral speed.

Such high-performance bag welding machines are e.g. known from DE-PS 14 79 807 and described in the unpublished DE-OSes 2810204, 28 10 127 and 28 46 220. However, the conveying device described here can also be used with the less efficient bag-making machines which work with a sealing strip which can be moved up and down and with a film web fed in batches.

The welding machine 302 shown in FIG. 6 has a continuously but non-uniformly rotating welding roller 15, to which a longitudinally slit, tubular, thermoplastic film web 10 is fed from feed rollers (not shown) forming a conveying gap. The welding roller 15 forms a welding gap together with a counter roller 17 and carries the welding tool 16 which, at the welding gap when the welding roller 15 rotates in the direction of the arrow 18 shown in the drawing, together with the counter roller 17 rotating in the opposite direction in the sense of the arrow 19 shown in the drawing performs a separation welding in which a bag 20 is separated from the film web 10 and at the same time a side seam trailing in the conveying direction is formed on the bag 20 and a seam on the front edge of the tubular film web 10, which forms a leading side seam in the next bag.

Each of the two deflection devices 301 a and 301 b of the switch 301 has a plurality of conveyor belts 402 and 403 which run around one another in parallel vertical planes and whose conveying surface is designed to be air-permeable. The exemplary embodiment is a belt-like endless belt which is pierced by a large number of perforation holes. Each of the conveyor belts 402 and 403 is guided for rotation in the direction of arrows 311b and 311 via rollers 404 to 413 and 414 to 421, of which some rollers are arranged such that they can be adjusted in position as tensioning and adjusting rollers, which will be discussed in more detail below . In addition, the conveyor belts 402 and 403 are guided in the area of the switch around an associated deflecting roller 422 or 423, wrapping part of the circumference thereof, as shown in the figure. The two deflecting rollers 422 and 423 are arranged opposite one another in such a way that between the conveyor belts 402 and 403 wrapping around them a conveying gap is formed at the narrow point between the deflecting rollers 422 and 423, in which the bags 20 are fed to the narrow point between the deflecting rollers 422 and 423 will the forms the deflection point of the switch 301. The rollers 409, 410, 411 and 417, which guide the conveyor belts 402 and 403, are arranged relative to the output end of the bag welding machine 302 such that the conveyor gap, forming the first conveyor, extends from the deflection point of the switch to the immediate vicinity of the welding machine, so that the bags 20 can be inserted directly into the conveyor gap.

In the present exemplary embodiment, the deflecting rollers 422 and 423, which rotate in opposite directions during operation in the directions of rotation indicated by arrows 424 and 425, are selected in such a way that their circumference is twice as large as the distance between the leading edges of adjacent ones, the bag supplied to the switch 20. Each of the deflecting rollers 422 and 423 also has a row of suction openings 426 and 427, which run along an axially parallel surface line of the deflecting roller, the inner sides of which are connected to a vacuum source, which is not shown in the drawing. The suction openings of the one deflection roller are 180 ° out of phase with respect to the suction openings of the other deflection roller, so that in connection with the size of the circumference of the deflection roller indicated above it is achieved that the suction openings of each deflection roller at the constriction between the rollers forming the deflection point of the switch the leading edge of each second bag 20 are aligned. In the example shown in the figure, the row of suction openings 427 of the lower deflection roller 423 is just at the deflection point. Due to the suction effect of the suction openings 427, an intake flow is generated in the adjoining area of the air-permeable conveyor belt 403 wrapping around the deflecting roller 423, which deflects the front edge of the bag 20 lying above this area downward during the rotational movement of the deflecting roller 423 in the direction of arrow 425, so that this bag 20 is fed for further transport to the second conveyor 303a shown below in the drawing. When the rear edge of this bag has passed the deflection point and the leading edge of the next bag 20 has entered the deflection point, the row of suction openings 426 has reached the area of the deflection point due to the specified circumferential size of the upper deflecting roller 422, so that due to the air permeable Conveyor belt 402 effective suction effect, this next bag 20 is now deflected upwards and is fed to the second conveyor 303b located at the top of the drawing for further transport.

Both of the air-permeable conveyor belts 402 and 403 interact in the region of the transport path which forms the second conveyor 303a and 303b, each with an associated auxiliary conveyor belt 428a or 428b, which are guided via associated tensioning and guide rollers 429a and 429b so that the Auxiliary conveyor belts on the conveyor line running from the switch 301 to the union 401 form a conveyor gap with the adjacent conveyor surface of the assigned, air-permeable conveyor belt 403 or 402, into which the bags 20 are transported to the union 401. At the merging point two deflecting rollers 432 and 433 rotating in opposite directions in the direction indicated by arrows 430 and 431 are provided, each of which has a series of suction openings 433 and 434, respectively, so that here in connection with the associated air-permeable conveyor belts 402 and 403 each a switch is formed, which the bags 20 fed from the second conveyors 303a and 303b feed a common third conveyor 436. With these switches, the size of the distance between the leading edges of the successive workpieces 20 is twice the size of the circumference of the deflecting rollers 432 and 433.

As already mentioned, the air-permeable conveyor belts 402 and 403 are guided by the rollers 404, 405 and 414, 421 in such a way that they form the third conveyor 436 and transport the pairs of bags placed against one another beyond the union point 401 via the downstream brake roller pair to the stacking location.

So that the path lengths of the transport routes of the second conveyors 303a and 303b can be easily adapted to one another in such a way that the supplied bags 20 are placed against one another at the union point 401 in a precisely aligned position, the rollers 415 and 416 are designed to be position-adjustable. At least one of the tensioning and guiding rollers 429a of the auxiliary conveyor belt and at least one of the rollers 417 to 421 of the air-permeable conveyor belt 403 located outside the conveying path are resiliently mounted for the tension compensation of the air-permeable conveyor belt 403 and the auxiliary conveyor belt 428a which is necessary due to the positional adjustment of these rollers. At least one of the rollers of the rollers leading the air-permeable conveyor belt 402, which is located at the top in the drawing, is also arranged to be flexible or positionally adjustable for tension compensation. For example, the rollers 409 and 410 can be designed as an adjustable unit, so that the inlet gap of the first conveyor section can be adjusted.

Claims (19)

1. Conveyor device having a switch (301) which deflects workpieces selected from sheet- shaped workpieces (20) being fed sequentially in a row from a first conveyor to one of two additional conveyors (303a, 303b) by means of at least one guiding body (307a, 307b; 402, 403) having an endless circumferential surface, said guiding body being drivable supported to rotate its endless circumferential surface, the circumferential surface being at least partially perforated for sucking the leading edge of the selected workpiece, the perforated area (362a, 362b) being connected to a vacuum-space (345) at least during the deflection, characterized in that for workpieces (20) without inherent stiffness, there is provided at least one further guiding body (307a and 307b), both of the guiding bodies being driveable in such manner, that their circumferential surfaces rotate in opposite directions and create a conveying slot (312) into which the first conveyor discharges, and in that for the selective deflection of the workpieces (20), entering the conveying slot, into one of the two additional conveyors (303a, 303b), the perforated area (362a, 362b) of the circumferential surface of either the one or the other of the guiding bodies, each at a time can have vacuum applied to it.

2. Device according to claim 1, characterized in that the guiding bodies are developed as belts (307a, 307b; 402, 403), each of which runs around at least two cylindrical deflection bodies (308a, 309a, 31 Oa; 308b, 309b, 31 Ob; 404-411, 422, 432; 414-421, 423, 433), whereby the one deflection body (308a, 308b; 422, 423) is part of the switch, and in that for the connection of the perforated area of each belt with the vacuum-space (345) there is connected therewith at least one borehole (354, 426, 427) provided for in the deflection body being part of the switch, the mouth of said borehole being in coincidence with the perforated area of the belt in the course of the movement of the belt around the deflection body.

3. Device according to claim 1 or 2, characterized in that the perforated area in the belt (307a, 307b) is formed by at least one suction hole (358).

4. Device according to claim 3, characterized in that as a belt a toothed belt (307a, 307b) and as deflection bodies toothed-belt discs (308a, 308b) are provided, in that the suction hole (358) is located in the bottom land (359) between two teeth (361) of the toothed belt (307a, 307b) and in that the mouth (357) of the borehole (354) is located at the top land (355) of a tooth (356) of a toothed-belt disc (308a, 308b).

5. Device according to claim 4, characterized in that the number of teeth (361) of the toothed belt (307a, 307b) is an integer multiple of the number of teeth of the toothed-belt disc (308a, 308b) at the outlet of the switch.

6. Device according to claim 4 or 5, characterized in that in the toothed-belt disc (308a, 308b) there is a plurality of boreholes (354) whose mouths form at least one row in the direction of travel of the toothed belt (307a, 307b), and in that a corresponding number of suction holes (358) is provided for in the toothed belt.

7. Device according to one of the claims 4 through 6 characterized in that the mouth of the borehole (357) is widened in the top land (355) of a tooth (356) of the toothed-belt disc (308a, 308b) beyond the cross-section of its borehole at least in the direction of the width of the tooth.

8. Device according to one of the claims 6 or 7 characterized in that a row of borehole mouths (357) extends over a section of the circumference of the toothed-belt disc which is at most as long as the length of the section of the circumference of the toothed-belt disc which is wrapped by the toothed-belt (307a, 307b).

9. Device according to one of the claims 2, 3 or 8, characterized in that as deflection bodies deflection rollers (422, 423, 432, 433) are provided.

10. Device according to one of the claims 1 through 9, characterized in that the deflection body (422, 423) has an axial length which corresponds at least to the width of the widest workpiece (20) to be fed to the switch (301 and in that a conveyor belt, the width of which extends over the greater part of the axial length of the deflection roller, or a plurality of narrower conveyor belts (402, 403) travelling alongside of each other and which together cover the greater part of the axial length of the deflection roller, is or are provided.

11. Device according to one of the claims 2 through 10 characterized in that the belt (307a, 307b; 402, 403) which serves as a guiding body also forms a conveying surface for the first conveyor which feeds the workpieces (20) to the switch (301).

12. Device according to one of the claims 2 through 11 characterized in that at least the belt (402, 403) which can be driven in one rotational sense is also used for constituting the conveying surface of one (303b) of the second conveyors (303a, 303b).

13. Device according to one of the claims 1 through 12 characterized in that the conveyor belts of the second conveyors (303a, 303b) come together at a combination place (401), and in that the conveyor phase of the two second conveyors (303a, 303b) and the lengths of the conveyor paths are so adapted to each other that at the combination place (401) the workpieces (20) fed by the two second conveyors (303a, 303b) rest against each other in coincidence.

. 14. Device according to claim 13, characterized by at least one auxiliary conveyor belt (428a, 428b) which constitutes with a corresponding belt (403 respectively 402) forming a guiding body of the corresponding second conveyor (303a, 303b) a conveying slot, in which the workpieces (20) can be fed from the switch (301) to the combination place (401).

15. Device according to one of the claims 2 through 14, characterized in that at least one conveying belt (402, 403) is provided, which is permeable to air due to a region which is permeable to air and which extends over the entire length of the belt.

16. Device according to claim 15, characterized in that the region of the conveyor belt (402, 403) being permeable to air is formed by perforation holes.

17. Device according to claim 13 and one of the claims 15 or 16, characterized in that there are at least two conveyor belts permeable to air (402 and 403) which form the two guiding bodies of the switch (301) and one conveying surface of each of the second conveyors (303b respectively 303a) and which are brought together at the combination place (401) for the creation of a third conveyor (436) by means of one deflection roller (432 respectively 433) each, which have at least one suction aperture (434 respectively 435) at their circumferential surface.

18. Device according to one of the claims 2 through 17, characterized in that the axes (313a, 313b) of the guiding bodies (308a, 308b) at the switch outlet are arranged in a plane which forms an angle of less than 90° with the plane of the conveying slot at the end of the first conveyor.

19. Device according to one of the claims 1 through 18, characterized in that the switch (301) is arranged behind a welding machine (302) having a continuously rotating welding strip (16) for the production of bags (20) of thermoplastic resin, and in that the frequency of rotation of the guiding body is synchronized with the frequency of motion of the welding strip.

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