EP0456604A1 - Making, maintaining and tensioning a tying loop - Google Patents

Abstract

A tying machine for packaging articles in stack form comprises a band guide (12) limiting the extension of the loop and having a sliding surface (16). During the advance and after the end position has been reached, a winding band (18) is maintained by pneumatic means in a loop form determined essentially by the sliding surface (16), during the band pull-back is drawn out of the band guide (12) without the movement of any mechanical parts and is laid round the packaging articles. The band guide (12) with the sliding surface (16) and lateral guides (36, 38) for maintaining the winding band (18) in a loop form has exclusively pneumatic means.

Description

The present patent application relates to a method and a device for forming, holding up and tensioning a loop around the packaged goods of a banding machine, which comprises a band guide which limits the expansion of the loop and has a sliding surface.

A banding machine processes square, rectangular, round or trapezoidal stacks by connecting them with at least one band - simultaneously or in succession. The packaged goods can be hard or very soft. For example, printed matter, trimmings, envelopes, labels, banknotes, checks, business cards, books, brochures, newspapers, booklets, signs, but also pharmaceutical products, textile products, stockings, vegetable products, cheese boxes, meat packs, shoe soles or the like can be bound in batches.

A banding machine works semi or fully automatically. A winding tape made of paper, plastic-coated paper or plastic forms a loop into which the stack to be bound, the packaged goods, is introduced. Controlled by a sensor or triggered by a hand or foot switch, the wrapping tape clamped at its free end is pulled back until it is snug against the packaged goods. Soft stacks can be compressed more or less by hand. Then the clamped end is glued to the tightened tape or welded and cut off.

EP-A2 0057471 describes a method and a device for forming and tensioning a strapping loop around a packaged product. The loop is formed by pushing the band along a circular guide surface up to a stop and then pulling out the small loop the level of the guide is turned out, creating a free-standing arch. The packaged goods are introduced and banded into the expanded large sheet. Neither the method nor the device for the strapping can be used for banding machines, which work with much thinner and smoother binding materials.

In the case of banding machines of known design, mechanical suspension means or support means must be used to form and maintain a winding tape loop of greater widths. This is the only way to make a large processing range possible without the loop bending before it is fully expanded or before the stack is introduced. However, relatively complex devices are accepted, which must be synchronized to the work cycle.

The disadvantage of complex mechanical means for forming and holding up a winding tape is prevented by a known, automatic loop formation in that the tape is guided from one side horn to the other and thus remains cantilevered. Although this solution represents a significant advance, it still has disadvantages:

- A relatively stable wrapping tape must be used, which has the rigidity necessary to hold it up freely.

- The width of the stacks of packaged goods to be bound with a banding machine is relatively narrow; above 240 to a maximum of 320 mm, a band of normal thickness and rigidity can no longer remain unsupported, even if it is of good quality.

The inventor has therefore set himself the task of creating a method and a device of the type mentioned at the outset which permit automatic formation of loops of any required width, even with thin, inexpensive winding tapes, without having to use mechanical means for holding them up. The loop formation should be done economically with a simple device.

With regard to the method, the object is achieved according to the invention in that the winding tape is kept in a loop shape essentially given by the sliding surface during the advancement and after reaching the end position and is pulled out of the tape guide during the tape retraction without moving mechanical parts. Special embodiments and further developments of the invention are the subject of dependent claims.

Apart from the pneumatic holding up of the loop which is being formed and formed, the banding takes place in the usual manner, with a working cycle of about 20 to 30 tapes per minute.

Multiple banding can be carried out simultaneously by inserting the stack of packaged goods into a band guide or by arranging two or more band guides of a banding machine.

According to a first method variant of the invention, a vacuum is generated by the pneumatic means in the area of at least part of the sliding surface. A vacuum that is only a few millibars below normal pressure can suffice to form and hold up a winding tape loop made of thin material. For the time being, a small loop is formed by means known per se, which is widened by quickly pushing the winding tape. Nice the loop is sucked in near the gliding surface and held up until it retracts after reaching the end position. Too strong a vacuum would interfere with or even prevent the winding tape from sliding during the widening of the loop and / or would lead to static charges for certain materials.

According to a second method variant, an air flow flowing obliquely upwards is directed from at least part of the sliding surface from the outer lower edges of an essentially U-shaped band guide which is open at the bottom and is diverted from there. Analogous to a weak negative pressure, a slight excess pressure is sufficient to carry a winding tape pushed along the sliding surface of the tape guide. The injection effect generated is sufficient to suck in the loop widened in the vicinity of the sliding surface.

The pneumatic means for generating a negative or positive pressure are preferably switched on and off with the banding machine. Since only low negative or positive pressures are generated, the energy used during idle time is negligible, especially since the machine is shut down anyway in the event of longer interruptions. Of course, the banding machine can be equipped with a switch that can be operated manually or by foot pressure, which allows the pneumatic means to be switched on and off separately. Finally, the actuation of the pneumatic means can also be sensor-controlled, especially if the banding machine is only used periodically to bind individual stacks. This sensor position can be set, for example, with the manual on and off switch.

With regard to the device for carrying out the method, the object is achieved according to the invention in that the belt guide with the sliding surface and side guides for Holding up the winding tape in the form of a loop has only pneumatic means. Special embodiments and further developments of the invention are the subject of dependent claims.

No mechanical supports or support surfaces of any kind are required to hold the winding tape up.

The length of the belt guide determines the width of the packaged goods that can be bound with the banding machine. This can be extended to about 50 cm and more without adjusting the belt quality and thickness due to the machine.

The band guide is designed so that it can be appropriately dimensioned on all commercially available banding machines, expediently with just a few simple steps. Mounting kits that allow the horns of a banding machine to be plugged in have proven to be particularly advantageous.

The tape guide can also be adjustable in length according to known principles of the designer, for example by being telescopically extendable.

One pneumatic means is used to generate a negative pressure, the other to generate an excess pressure. However, both negative pressure and positive pressure are only slight, they preferably differ only slightly from normal pressure, for example in the range from 5 to 100 Mb (millibars).

In order to generate a vacuum between the belt guide with the sliding surface and the side guides on the one hand and the winding belt on the other hand, the latter has at least one opening above which a suction fan or a suction pipe or a suction hose of a suction fan is arranged. Because he has poor performance must have, the fan or the fans are designed to be relatively small and inefficient, which is advantageous in every respect. The suction generated only has to hold up the winding tape.

When forming loops by widening, the winding tape must also be able to slide along the sliding surface, even if only slightly, without this being opposed by any substantial resistance. Therefore, the wrapping tape may only adhere a little.

A fan with a corresponding opening in the longitudinal direction of the belt guide can preferably be moved to different positions depending on the belt quality. The same applies analogously to a suction hose with a corresponding opening. In this way, an expanding loop can be optimally detected. If several openings assigned to a suction fan or suction hose are arranged in a sliding surface, these can of course also be moved in the longitudinal direction of the belt guide.

In order to avoid bulging of the winding tape in large-dimensioned opening / s of the sliding surface associated with a suction fan or suction hose, support webs are arranged which run approximately in the longitudinal direction of the tape guide.

If at least one opening mentioned is arranged, the sliding surface is preferably smooth and consists at least on the surface of a material which causes no or only a slight static charge when the winding tape is displaced.

Instead of at least one large-area opening, the sliding surface can be at least partially perforated, perforated or slotted and have a chamber with a corresponding negative pressure between the sliding surface and the band guide.

Finally, the sliding surface can at least partially consist of a fabric, knitted fabric, fleece or fine-mesh net, but care must be taken to ensure that the winding tape can also slide.

After all variants of the formation of the sliding surface, with one opening, several openings or perforations, ribs running in the longitudinal direction can be arranged, which in turn form a new sliding surface formed by the ribs at a distance from the rear wall of the band guide. This variant is particularly advantageous for strip materials which, in combination with the sliding surface, tend to become static. Furthermore, if only a single suction opening is formed, the suction effect can be better distributed and developed earlier. In this case, however, the air flow is not prevented by the belt lying on it.

The suction means can be designed in such a way that a negative pressure is only generated in a part of the interstices between the ribs when the winding tape lies on it. For example, negative pressure can only be generated in / in the middle and / or the outer spaces.

As mentioned, a slight overpressure can be generated instead of a negative pressure, in that in a downwardly open, U-shaped band guide with a sliding surface, at the lower edge of the parallel legs, air outlet nozzles, holes and / or slots emerging in the direction of the sliding surface Air jet are arranged. The escaping air holds up the winding tape forming a loop. It is pressed lightly against the sliding surface or can be at least partially suspended.

Some of the nozzles, holes or slots can be directed forward in the direction of advance of the winding tape and cause a tape advance, which can be particularly advantageous with thin, soft tape material.

Another variant is that all air outlet nozzles, holes and / or slots are directed slightly forward and achieve the same effect.

Although the method and device according to the invention can be used for all known banding machines using all known winding tapes, the advantages with thin and soft tapes have a particularly advantageous effect. In particular in cooperation with feed nozzles, winding tapes can be made thinner and softer than previously customary and can nevertheless be used for wide loops.

• Fig. 1 eine aufgeschnittene Prinzipskizze einer Banderoliermaschine mit einer angeflanschten Bandführung,
• Fig. 2 eine perspektivische Ansicht einer in ihrer Längsrichtung verschiebbaren Bandführung,
• Fig. 3 eine aufgeschnittene Ansicht von an einer Bandführung angeschlossenen Saugschläuchen,
• Fig. 4 - 7 verschiedene Ausführungsformen von Gleitflächen mit Luftansaugung,
• Fig. 8 einen Querschnitt durch eine Bandführung mit Luftströmen, und
• Fig. 9 einen teilweisen Längsschnitt durch eine Bandführung mit einer Düsenleiste.

The invention is explained in more detail with reference to exemplary embodiments shown in the drawing, which are also the subject of dependent claims. They show schematically:

• 1 is a cut open schematic diagram of a banding machine with a flanged band guide,
• 2 is a perspective view of a tape guide displaceable in its longitudinal direction,
• 3 is a cutaway view of suction hoses connected to a belt guide,
• 4 - 7 different embodiments of sliding surfaces with air intake,
• Fig. 8 shows a cross section through a tape guide with air flows, and
• Fig. 9 is a partial longitudinal section through a tape guide with a nozzle bar.

On the banding machine 10 shown in FIG. 1, also called the banding machine, a band guide 12 with an internal sliding surface 16 is arranged by means of flanges 14. For the time being, a small loop of the winding tape 18 is formed with known means, which is pushed open into a large loop with a feed mechanism which is also known per se and is therefore not shown. The dashed line 18 'shows the widening loop in an intermediate stage, of course the packaged goods have not yet been inserted. The winding tape 18 shown in solid lines shows the final stage of the loop formation.

Of the devices arranged in the banding machine and known per se, such as feed rollers, counter-tensioning rollers, bandwidth adjustment, band clamps, hold-down devices and knives, for the sake of simplicity and clarity, only the welding plate 22 for connecting the advanced end face of the winding tape to the retracted winding tape 18 itself Feed is determined by the pinching time of the winding tape between the feed rollers rotating at constant speed. The retraction is triggered after a sensor 20 indicates that packaged goods 26 have been inserted, and is carried out by clamping the winding tape 18 between the tensioning rollers, in the opposite direction of the arrow 24. After the withdrawal with adjustable tensile force, the wrapping tape 18 encloses the inserted stack, the packaged goods 26 , Fed up. Of course, manual control can also take place instead of sensor control.

In the case of a large working width of a conventional banding machine, a wrapping tape of relatively great thickness and rigidity would have to be selected so that the width can be spanned. This would not only be expensive, but also impractical for the tight application of the winding tape to the packaged goods.

1, there is a suction fan 28 with an opening in the sliding surface 16 corresponding to the inner cross section cannot bend downwards if the clamping force across the width b is insufficient. However, the suction effect is not so great that moving is impaired.

With an even larger width b, a plurality of suction fans 28 can be arranged one behind the other.

The sliding surface 16 has lateral guides (not shown) in the form of a U which is open at the bottom in cross section (FIG. 2), in order to prevent the winding tape 18 from escaping.

Fig. 2 shows two nested, in the longitudinal direction L of the tape guide 12 mutually displaceable profiles. The outer profile 32 is - not visible - attached to two side horns of the banding machine. The outer profile 32 is essentially U-shaped with respect to the cross section, with the opening directed downward, it essentially corresponds to a sliding surface with side guides according to FIG. 1.

An inner profile 34 which is displaceable in the longitudinal direction L in the outer profile 32 has ribs 40 running parallel to the legs 36, 38 of the outer profile 32. These ribs 40 have support surfaces 39 which run at right angles on the end face and form the sliding surface 16. The legs 36, 38 designed as lateral guides project significantly beyond the ribs 40.

In Fig. 3 the sliding surface 16 of a very wide band guide 12 (Fig. 1) is shown. The low vacuum exerting a suction on the winding tape 18 is in one Fan not shown generated in the direction of arrow 42. Suction hoses 44 adjoin a total of three openings 30 in the sliding surface 16 and unite in the direction of the fan to form a common suction hose 46.

The suction hoses 44, 46 are designed so that the sliding surface 16 can be moved in its longitudinal direction (L).

FIG. 4 shows an opening 30 according to FIGS. 1 and 3 from below. Support webs 48 are arranged in the longitudinal direction L of the band guide. These prevent a thin, relatively flexible winding tape 18 (FIGS. 1, 3) from being sucked into the relatively large opening 30 despite the low negative pressure.

In the embodiment according to FIG. 5, at least part of the sliding surface 16 is designed as a perforated plate with numerous small bores 50 with a diameter of a few millimeters, in FIG. 6 as a slotted plate with longitudinal slots with a length of a few centimeters and a width of a few millimeters.

7, at least part of the sliding surface 16 is designed as a fabric 54.

The band guide 12 drawn in cross section in FIG. 8 is essentially U-shaped, with the opening directed downward. The parallel legs 36, 38 each carry a nozzle strip 56 with obliquely upward air outlet holes at the lower end. The air flow can hold the winding tape 18 in suspension or press it lightly against the sliding surface 16 of the tape guide 12.

Air outlet openings, not shown, are formed in the sliding surface 16. Underneath the tape guide an injector action which sucks a light winding tape (18) when the loop is pushed open into the area of action of the nozzle strips 56.

When the tape is withdrawn, the winding tape 18 can be pulled out of the tape guide 12 and stretched around the packaged goods without any problems, as is the case with the vacuum variants, without any mechanical parts having to be moved synchronously.

FIG. 9 shows a partial longitudinal section through a tape guide 12 with the front edge 58 of the winding tape 18, which is advanced in the direction of arrow 60.

The nozzle bar 56 has individual nozzles instead of bores, the one nozzle 60 running perpendicular to the sliding surface 16, the other being designed as feed nozzles 62. In the case of thin, flexible belts 18 in particular, it may be advantageous to provide a feed.

Claims (12)

Method for forming, holding up and tensioning a loop around the packaged goods (26) of a banding machine (10), which comprises a band guide (12) which limits the expansion of the loop and has a sliding surface (16),
characterized in that
a winding tape (18) is held up during the advancement and after reaching the end position by pneumatic means in a loop shape essentially given by the sliding surface (16) and is pulled out of the tape guide (12) during the tape retraction without moving mechanical parts. A method according to claim 1, characterized in that a negative pressure is generated in the area of at least part of the sliding surface (16). A method according to claim 1, characterized in that in the area of at least part of the sliding surface (16) an air flow flowing obliquely upwards from the outer lower edges of the legs (36, 38) of a substantially U-shaped band guide (12) open at the bottom is judged. Method according to one of claims 1 to 3, characterized in that the pneumatic means are switched on and off automatically with the banding machine (10), manually with a hand switch and / or automatically with sensors. Device for carrying out the method according to one of claims 1 to 4, characterized in that the tape guide (12) with the sliding surface (16) and side guides (36, 38) for holding up the winding tape (18) in loop form has only pneumatic means. Apparatus according to claim 5, characterized in that the preferably length-adjustable band guide (12) is detachably connected to the banding machine (10) with a few hand movements or can be plugged onto its horns. Apparatus according to claim 5 or 6, characterized in that the sliding surface (16) of the belt guide (12) has at least one opening (30, 50, 52) through which a suction fan (28) or a suction pipe or a suction hose ( 44) of a suction fan (28) is arranged, which between the sliding surface (16) and winding tape (18) generates a vacuum and thus a suction. Apparatus according to claim 7, characterized in that the suction fan (s) (28) or the suction hose (s) (44) with their suction opening (30) are adjustable in the longitudinal direction (L) of the belt guide (12), and the Suction opening (s) preferably have support webs (48) running in the longitudinal direction (L). Apparatus according to claim 7, characterized in that the sliding surface (16) is at least partially perforated, perforated or slotted or at least partially consists of a fabric, knitted fabric, fleece or fine-mesh network. Device according to one of claims 8 or 9, characterized in that the sliding surface (16) consists of the contact surfaces (39) of longitudinal ribs (40), at least some of the spaces (41) between the ribs (40) when the winding tape () 18) has a negative pressure. Apparatus according to claim 5 or 6, characterized in that the band guide (12) is substantially U-shaped, open at the bottom, and the lower edges of the parallel legs (36,38) air outlet holes, slots and / or nozzles (60,62) with an air jet emerging in the direction of the sliding surface (16). Apparatus according to claim 11, characterized in that at least some of the air outlet holes, slots or nozzles are designed as feed nozzles (62) for the winding tape (18).

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