EP0870679A1 - Package strapping machine - Google Patents

Abstract

A reel of thermoplastic strap (55)is rotatably mounted onto the side of the device and a feeds into the device through a pair of motor driven rollers (16) to a store area (17). A second pair of reversible friction rollers (18) drive the strap into the strap guide channel (12) via a high tension tightening drum (19) followed by a strap clamp (20) and guide channel (21) to the closing unit (15). When the package is wrapped tautly via the reversible friction rollers, the end sections are overlapped and friction welded. Friction welding is achieved where clamps either side of the overlapping region press one strap section against a counter-support and an oscillator vibrates one strap end portion against the other at high frequency, causing a friction weld.

Description

The invention relates to a device for strapping of packages according to the preamble of the claim 1.

Vibration welding using a high Frequency driven vibrator is characterized that the transducer in the band closure area one of the two overlapping band sections in high frequency vibrations relative to the other Belt section moves, which creates frictional heat, the areas of the overlapping areas touching each other Sections of tape melt so that they melt together be cohesively connected.

From DE 17 61 166 B1 it is known to use the "vibrator" mentioned vibrators swing in the longitudinal direction of the belt allow. Because the transducer against the tape tensile forces must work, especially when not or only slightly compressible packages none achieve high tension forces. Are also particularly high Driving forces on the transducer required. Furthermore the arrangement is such that the connection point of the overlapping band sections that in the Loop acting fully acts as this Tape material only between the vibrator and from the clamped on the other side of the hinge against him is. This type of strap closure training is very subject to wear.

In the device according to US 4,776,905 the overlapping band sections on one side pressed tightly next to the transducer, and the Schwinger moves the section of the tape he is attacking transversely to the longitudinal direction of the tape over that of a counterholder against it pressed second band section. Different to the oscillation of the transducer and that belonging to it This transverse movement leads to the end of the strip in the longitudinal direction of the strip of the tape in the manufacture of the sweat closure to a very strong shear stress from the Swinging band section. This can therefore during closure formation, especially at high Tear off the belt tension easily.

To tackle this disadvantage to some extent, in the abutment plate next to the transducer is a button-shaped, around an axis perpendicular to the belt rotatable clamp body arranged. This can however the transverse vibratory movements of the belt only increase intercept a very small part as it is only rotating Movements at a distance from the linear across the band can perform moving vibrator. Otherwise there is the problem of this friction welding device Band tears rather on the side facing away from the clamping device Side of the transducer. Since no second band clamp is provided and due to the thermal Strain on the belt during the formation of the closure only low clamping forces can be achieved.

A used training of the subject of US 4,776,905 provides instead of the button-shaped order its longitudinal axis freely rotatable band clamp this around a distant axis can also be swiveled to arrange. Such a clamp can cross Belt movement of the end of the belt carried by the transducer on a larger radius and therefore a little better but still not follow optimally. Otherwise exist the disadvantages mentioned in the subject of US 4,776,905 here too.

Furthermore, e.g. from EP 0 605 759 a friction welding device became known in which the transducer neither in the longitudinal direction of the belt nor in the transverse direction of the belt vibrates linearly, but as a ring disc is formed with an eccentric offset revolves perpendicular to the belt surface. Of the The belt section taken along by the vibrator is thus subject to a wobble or "wobble" movement. In the ring body of the vibrator is only spring-loaded Pressure piece integrated to the band ends in Leading range of the transducer or against each other to keep. With the corresponding, executed in practice The device is located in the tape running direction in front of and behind this vibration welding unit, band clamps, which basically allow the strap closure under the tension of the strapped tape, but the tape is in the fastener area all directions more or less heavily loaded. Around the occurring shear stress on the belt sections to be limited, those not shown in EP 0 605 795 A1, on the practical machine however existing band clamps in front of and behind the in Vibration lock assembly very far apart, around long, freely movable belt sections to have and to be able to take advantage of their stretch. However, this results in the disadvantage that no small ones Packages, e.g. Bar material to be strapped can.

Also DE 40 14 305 C2, of which the present one Invention is concerned with the problem that adverse consequences of band stress in one Vibration welding area in which the to each other connecting band sections overlap each other and being in front of and behind this closure area arranged a clamp holding only one band section is. Here the arrangement is such that the band clamp on the band section attacked by the transducer itself thanks to a mechanical, active drive in sync with the vibrator is driven and taking it with it of the band section parallel to the swinging movement of the transducer moves, this swinging motion perpendicular to the longitudinal direction of the belt.

So that the driven jaw of the belt section can also take it effectively, this will the side facing away from the jaw against a smooth Abutment surface pressed. On the one hand, this results high friction forces and consequent wear, on the other hand, the smooth surface of the Abutment naturally to lower clamping forces. The fact that the jaw is actively driven the mechanical complexity of the device is large.

Proceeding from this, the object of the invention based, a device for strapping packages according to the friction welding process according to the generic term of claim 1 to create a closure training permitted under high belt tensile forces, which is also able to carry relatively small packaged goods strapping high strap tension and at the on complex no additional drives for unit parts can be.

The invention solves this problem with the features of claim 1 and is characterized accordingly, that the transducer oscillates about an axis, which runs through the movable jaw and that this around the same axis in the same direction as the transducer oscillates, but only from the vibrating band section is carried along.

Because the oscillator oscillates around an axis, that runs through the movable jaw, the transducer leads a circular arc around this axis Moving back and forth across a segment of a circle out. Its movement is only at one point in the trajectory oriented perpendicular to the belt longitudinal direction, so that the band section is much less is claimed for shear. If the jaw now according to the same axis according to the same axis the oscillator oscillates, act between the jaw and the band held by her has no relative movements. According to the invention However, the jaw is not driven, it is only carried by the vibrating band section.

Carrying the jaw in this sense was with the prior art referred to so far not provided.

An optimal vibration synchronous carrying of the Jaw is by the vibrating band section according to a further embodiment of the invention especially given when moving Jaw interacting abutment one section of the transducer itself. This leads to the further one Advantage that all surfaces of transducers and Jaw that comes into contact with band surfaces, designed to increase friction, in particular roughened or can be serrated, because between these one another contacting surfaces there is no slip. The The consequence of this is that the clamping jaw has very high clamping forces can exercise. It is also a very simple one Design realized.

Leave the oscillator and freely movable clamping jaw integrate in a particularly favorable way, that the transducer is attached to the end of a hollow shaft which is the movable jaw axially displaceable as well as rotatable.

According to a further embodiment of the Invention is provided that the friction surface of the Transducer with the opposite surface of one Vibration abutment formed an inclination angle, pointing away from the vibrating axis of the transducer opens in the direction of the tape and has an order of magnitude of approximately 0.3 ° to 1.0 °. This will make the different Distance from band sections to the oscillation center in coordination with the pressure forces that occur taken into account in an advantageous manner. From away from the oscillation axis the pressure forces increase increasing vibration path according to the angular inclination continuously. This will be an extraordinary achievement uniform stress on the unit parts and the tape over the length of the closure created away and a completely homogeneous weld.

The oscillation angle of the transducer is otherwise preferably small and of the order of magnitude from about 4 ° to 5 °.

According to a further feature of the invention forms the transducer the head plate of the Band closure unit is at the end of the hollow shaft attached and cantilevered from there into the strap level a. Because of this conception, the entire tape closure unit from the closure area swing out, with its simple way and Way released the strap loop surrounding the package can be. Also the means of control can be very simple. In this regard the features of claims 8 to 10 of importance. A Another particular advantage is that the drive shaft forms a central drive via the all stroke-controlled functional parts of the strap closure unit can be clock controlled.

Fig. 1

eine Umreifungsmaschine in schematischer Ansicht,

Fig. 2

eine schematische Darstellung des Bandverschlußaggregats in einer ersten Stellung nach dem Einschießen des ein Packstück umgebenden Bandes,

Fig. 3

eine der Fig. 2 entsprechende Darstellung des Verschlußaggregats mit um das Packstück herum gestraffter Bandschlaufe,

Fig. 4

einen gegenüber Fig. 3 vergrößerte Darstellung nur des Verschlußbereichs der Vorrichtung, wobei zur Verdeutlichung sämtliche Flächenrauhungen nicht dargestellt sind.

Fig. 5

einen der Betriebsstellung der Fig. 3 und 4 entsprechenden schematischen Querschnitt durch das Verschlußaggregat im Bereich des Schwingers,

Fig. 6

eine vergrößerte Darstellung zur Erläuterung von Geometrie und Funktion von Schwinger und Klemmbacke, und

Fig. 7

eine Fig. 4 entsprechende Darstellung der Aggregatstellung am Ende eines Arbeitszyklus.

Otherwise, the invention is best understood on the basis of the following explanation, using an exemplary embodiment shown in the drawings. The drawings show:

Fig. 1

a strapping machine in a schematic view,

Fig. 2

FIG. 2 shows a schematic illustration of the band closure unit in a first position after the band surrounding a package has been shot in, FIG.

Fig. 3

2 shows a representation of the closure unit with a strap loop tightened around the package,

Fig. 4

an enlarged view compared to FIG. 3 only the closure area of the device, all surface roughening not being shown for clarity.

Fig. 5

3 and 4 a schematic cross section corresponding to the operating position of FIGS. 3 and 4 through the closure assembly in the area of the oscillator,

Fig. 6

an enlarged view to explain the geometry and function of the transducer and jaw, and

Fig. 7

a Fig. 4 corresponding representation of the aggregate position at the end of a work cycle.

A band strapping machine in its entirety is designated by 10 in FIG. 1. On your machine frame 11 is a substantially closed Band guide channel 12, through and around with package 13 indicated by dash-dotted lines around a thermoplastic plastic tape 14 one Band closure unit 15 is supplied. Its job consists of overlapping end portions of the around the package 13 led band 14 by means of Friction welding to be welded together by exposure to heat.

The belt 14 is outside the machine frame 11 on a rotatably mounted tape reel (drum 55) stocked. First, the belt 14 passes through on the machine input side a pair of rollers 16, which two to each other opposite hinge surfaces frictionally has attacking roles that towards each other tensioned and thus held with pressure against the band 14 are. The motor drive of this pair of rollers 16 conveys the tape 14 into a tape storage 17, the one such length of tape 14 stored tension-free, such as he at least for the following strapping and for the Distance of the belt 14 to the sealing unit 15 is needed.

Following the tape storage 17 in the tape feed direction a second pair of rollers 18 is arranged. Also the two rollers of this pair of rollers 18 drive the belt 14 frictionally. This pair of rollers 18 is reversible driven, because it serves the one shot of the tape 14 in the tape guide channel 12 and, with opposite drive direction, on the other hand that Retraction of the band 14 and its tightening around the package 13. In the latter sense, the pair of rollers is 18th a so-called "low tension clamping device".

In the tape feed direction is the weft and retraction roller pair 18 another "high tension clamping device" subordinated by means of tension drum 19, the Subject of another patent application and not here is of further importance. On this tension drum 19 a special band clamp 20 and a guide channel follow 21 through which the band 14 made its way to Band closure unit 15 takes.

Fig. 2 illustrates details of the tape lock assembly 15. According to this illustration was the band 14 by means of the weft roller pair 18th through the tension drum 19 and through the belt guide 21 fed through the tape closure unit 15 until the leading end of tape 14 'against a so-called bullet switch 23 ran.

On its way there has free leading Band end 14 'a separator slot 24 in a first Pass through the band clamp 25 and then one of the band guides serving separator 26 within a so-called "Weld clamp" 27. The two separator slots serve the band sections in their common overlap area keep away from each other and an unobstructed cut off of the lower one To enable band section.

The actuation of the entry switch 23 by the Leading, free tape end 14 'signals the machine control the machine starting position and leads practically a 'reset'. This starting position is characterized in that within the tape guide channel 12 (Fig. 1) is already a strapping Section of the tape 14 is ready.

At the press of a button then initiated machine command the strapping process begins itself, after a package 13 has been placed in the channel 12. The pair of rollers 18 receives the command to reverse Drive and pulls the tape 14 back, which accordingly the friction forces exerted by the pair of rollers 18 to tighten the package 13 because the first band clamp 25 the front band section 14 ' presses against the lower surface of the head plate 22.

Should the package 13 with a higher belt tension acted upon as the "low tension" pair of rollers 18 can impress the band 14, turns itself the "High Tension" tensioning drum 19 rotating in the belt tensioning process and thereby tightens the ligament with stronger Tension.

Such a taut band condition shows Fig. 3, which also shows that the separator 26 (Fig. 2) from its operating position there has been swung out sideways, whereupon the Weld clamp 27 and a second one, which is arranged outside next to it Band clamp 41 have been moved upwards, which now also holds the tape 14 here.

A cutting knife attached to the weld clamp 27 46 has the length of strap required for strapping separated from the tape supply. Now that's about that Package 13 tightened band 14 in the welding position to form a strap closure.

This position is - accordingly also Fig. 4, the the essential functional parts larger than Fig. 3 shows - mainly characterized by the fact that the front End of band from jaw 25 'of the first band clamp 25 in cooperation with the head plate 22 on the one side of the closure formation zone is held, while the jaw 41 'of the band clamp 41 the other Strap end 14 '' on the other side of the strap closure zone presses against a clamping abutment 42. Every jaw 25 'and 41' thus holds only one band section each firmly, and the overlapping band sections 43 and 44 to be connected together are located in the band closure zone in between. The Strap closure zone is from resulting from strapping Belt tension forces kept free.

The top plate 22 is also a vibrator or Vibrator and about a vertical axis designated 29 driven oscillating. The axis of oscillation 29 is at the same time the central axis of the band clamp 25 Clamping jaw 25 'which can rotate freely around this axis is. Specifically, the arrangement is made so that the bearing shaft 30 of the band clamp 25 in a Hollow shaft 31 is guided. 5 and 7 show is the hollow shaft 31 with the oscillating head plate 22 Movementally connected.

The vibrator 22 is driven by means of a motor 33 flanged to a bearing block 32, a tuning fork 35 via an eccentric shaft 34 drives oscillating, with the hollow shaft 31 rotatably connected is. Thus, the vibrator 22 performs oscillating Movements around the vertical axis 29. This is shown in Fig. 6, the one end position the swinging motion with solid, the other with dash-dotted lines is shown. Shown is a top view of the transducer 22, the partially erupted to the one below To make jaw 25 'of the band clamp 25 visible.

The oscillatory movement of the vibrator 22 leads on the one hand the band section 43 on which the Vibrator 22 attacks, relative to that of the weld clamp 27 held opposite band section 44 moved back and forth across a sector of a circle becomes what becomes frictional heat and thereby softening of the mutually facing surfaces of the overlapping Band sections leads. The oscillation angle is with about 4 ° to 5 ° small, which is both for protection of the belt and the aggregate parts contributes as itself also reduces wear and noise.

For the optimal distribution of pressure forces during of the friction welding process is the most Band section 44 engaging surface 28 to the lower surface 22 of the vibrator, which engages the band portion 43 to inclined at an angle w. The angle w, its apex lies in or close to the oscillation axis 29, opens from there across the clamping section Outside. By the angle of inclination w, which is about 0.7 ° is a coordination between the friction path and Pressure force reached that the force with increasing oscillation path, i.e. in the direction of itself opening angle w, becomes slightly smaller. Also this contributes significantly to low wear and low noise the device and a homogeneous weld at.

The band section oscillatingly moved by the oscillator 22 43 is the first of the jaw 25 ' Band clamp 25 also against the bottom of the Vibrator 22 pressed so that the vibrator 22nd oscillating belt section 43 rotatably guided in the hollow shaft 31 of the vibrator 22 Clamping jaw 25 'of the band clamp 25. This will the shear forces acting on the band section 43 kept so low that they are not harmful Effects on a secure closure, including under high belt tension can occur.

After the tape closure in the described Has been produced, the band clamps 25 drive and 41 and the weld clamp 27 with respect to the drawings back down, and all stroke-controlled Facilities of the closure unit, in particular the Vibrator 22 and the band clamp 25 integrated in it are pivoted sideways out of the band closure plane. This is shown in Fig. 7, in which also the previous already swung out in the opposite direction Separator 26 can be seen.

The control of the moving functional parts takes place centrally via a control shaft 45 with control cams 47 for the stroke-controlled band clamp 25, one Control cam 48 for the welding clamp 27 and one Control cam 49 for the second band clamp 41. As a result the swinging out of the unit parts can do that strapped package particularly easy from the machine table remove.

Claims (10)

Device for strapping packages with a thermoplastic band, which is fed from a band supply into a band guide channel surrounding the package and through this to a band closure unit, which connects overlapping band sections in the band strapping plane by means of friction welding, with in front and behind the overlap area in each case a clamping jaw for pressing a band section against an abutment is provided and in the overlap area of the band sections an oscillator driven in oscillation parallel to the band plane sets the band section facing it in relation to the other in high-frequency, frictional heat generating vibrations and thereby welds the band sections together, and wherein the clamping jaw of the band section on which the vibrator engages is movably arranged in and against at least one direction parallel to the band plane, characterized in that the Sc hwinger (22) oscillates about an axis (29) which runs through the movable clamping jaw (25 ') and that this oscillates in the same direction with the oscillator (22) about the same axis (29), but is only carried along by the oscillating belt section (43) . Device according to claim 1, characterized in that with the movable jaw (25 ') interacting abutments a section of the transducer (22) is itself. Device according to claim 1 or 2, characterized characterized in that the oscillator (22) at the end of a Hollow shaft (31) is attached, which is the movable Clamping jaw (25 ') axially displaceable and rotatable stores. Device according to one of claims 1 to 3, characterized in that the friction surface (22a) of the Schwingers (22) with the opposite surface (28) a vibration abutment (welding clamp 27) includes an angle of inclination (w) that is different from the Swing axis (29) of the oscillator (22) shows the way in Belt direction opens. Device according to claim 4, characterized in that the angle of inclination (w) is an order of magnitude from about 0.3 ° to 1.0 °. Device according to claim 1 or one of the following, characterized in that the oscillation angle of the transducer (22) is of the order of magnitude of approximately 4 ° to 5 °. Device according to claim 1 or one of the following, in particular according to claim 3, characterized in that the transducer (22) to the package (13) Pointing head plate of the strap closure unit (15) forms, is attached to the end of the hollow shaft (31) and from there freely on one side into the strap level claws in. Device according to claim 1 or one of the following, characterized in that the the transducer (22) associated movable band clamp (25) one Has hollow shaft (31) through shaft (30), which forms the plunger for their stroke control, which front of a control surface as part of a Control element such as cam (47) or cam disc can be acted upon is which control element is parallel to one another drive shaft extending to the strapping plane (45) is attached. Device according to claim 8, characterized in that the drive shaft (45) control members (47; 48; 49) for all stroke-controlled functional parts of the Band closure unit carries and thus a central drive trains. Apparatus according to claim 8 or 9, characterized characterized in that the stroke-controlled tape closure unit parts such as band clamps (25, 41), band severing knife (46) and transducer abutment (27) and those with them interacting lifting-resistant functional parts such as transducers (22) and clamping abutment (42) in a common Carrier (50) are guided or held, the order The axis of the central drive shaft (45) is pivotally mounted is and by means of additional moved by it Control surfaces can be pivoted in such a way that the tape closure unit (15) overall temporarily from the Strap strapping level is controllable.

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