DE19614634A1 - Ultrasonically welding ends of thermoplastic packaging belt - Google Patents

Abstract

An assembly heat-welds the two ends of a thermoplastic belt providing outer security for a small package. The belt is tautened around the package and the two ends are heat-joined using ultrasonic energy while resting between a two-part (4,5) locking plate (3). The energy is imparted to the plate by an emitter (13). This emitter may be rotated back and forth about its longitudinal axis, or by a pressure shoe.

Description

The invention relates to a device for connecting the ends of tapes or the like used in setting goods, for example of tapes comprising thermoplastic material, with a Support for the ends of the tapes serving ent removable plate and with a movable over the plate and against the ends of the straps adjustable on the plate.

It is known to tie all kinds of goods, tapes around the goods to lay and tighten, so that the straps the goods with a certain pretension, but without the goods or their Damaging packaging. The ends of each band, especially if the tapes are made of thermoplastic material or at least have thermoplastic material, for example made of polypropylene or other thermoplastic, by Heat combined, d. H. with each other, so to speak welded.

It is known to pass through the superimposed ends of the tapes to warm up high-frequency vibrations and towards each other press so that the superimposed ends of the tapes are together be welded. For this you need a plate as a base, on which the ends of the tapes to be welded together lying, and one against this plate or those lying on it Bands adjustable head, the high-frequency swinging movements of for example 20,000 hertz, which is sufficient to match that of to warm the band ends touching the vibrating head so much that their material becomes at least doughy in order to weld the To bring the ends of the tape. The tape is also in places heated, where no welding takes place.  

As the band ends are welded after the transport has been tied goods on the goods must be exported as a document seen plate not moved during the welding process between attached to the relevant volume and the goods and must, according to Ver welding can be pulled out. The tapes must therefore with a certain preload around the goods or the goods to be set because the plate used as a base takes up space and after pulling out, the tape tension is loosened. This is Especially problematic with smaller containers, because the pre can not adjust the tension of the straps arbitrarily, otherwise you can If the tapes damage the packaged goods or their packaging. The problem arises, especially in the case of smaller containers, that after pulling out the washer, do not remove the tape in question more sufficiently firm, but only loosely the packaged goods wraps around.

The thickness of the base plate can not be chosen arbitrarily small because they have a certain stiffness to perform their function must have.

The invention has for its object the ends of for tying connect strips of goods used together and ins special to be able to weld together that by removing the belt used here does not feel the belt tension sinks and nevertheless a firm and permanent connection of the superimposed tape ends is achieved.

According to the invention, this object is achieved with a device which has the features of claim 1. Advantageous Ausge Events and developments of the device according to the invention are the subject of the subclaims.  

With the device according to the invention it is possible to the Plate to be deposited in the immediate welding area to make extremely thin, namely in that the plate is divided into two and the head generating the welding heat is, for example, cylindrical is trained and are set in rotating vibrations can. The two-part plate is designed so that it is a Contains recess in which the head is retracted or indented can be. This way the plate is actually sweating to keep the area thin while using a cylindrical Welding head their thickness from the parting plane or dividing line starting increases, so that an undesirable bending of the plate under the pressure exerted on them during the welding process can occur.

The tape ends to be welded together take on use a slightly curved shape corresponds to a cylindrical welding head according to the curvature of the surface of the sweat head, but what is insignificant. It is crucial that the plate or its two Parts in the welding area can be kept very thin, so that the tension generated in the welded band hardly drops when the plate or its two parts from the area of sweat place pulls out.

The device according to the invention is particularly suitable for setting smaller packs or containers suitable for which already a Smaller voltage drop in the welded band after removal the welding device can have unfavorable consequences.

In the drawing are for further explanation of the invention Embodiments of the welding device according to the invention shown schematically, namely

Fig. 1 is an end view of the device with extended auseinanderge plate parts,

Fig. 2 shows a horizontal section through the device of Fig. 1 in the rest position with the plate parts moved apart and the welding head withdrawn.

Fig. 3 is a partial plan view of the two parts of the plate of FIGS . 1 and 2 in the operating position, wherein the rotatably mounted, cylindrical head is in the operating position and between the parts of the closed backing plate and the cylindrical head ends of a band can be recognized

FIG. 4 is a partial section of FIG. 3, enlarged in scale, from which the roughened surfaces of the parts of the backing plate and the cylindrical head can be seen,

Fig. 5 is a plan view. 3 a further From guide die similarly as in Fig, in which the ends of the tape off and mounted retractable heating tongue are heated by means of one of the two parts of the back-up plate before they are pressed against each other by means of a plunger,

Fig. 6 is a plan view of the apparatus of FIG. 5, wherein the two parts of the back-up plate are moved apart and the successive welded ends of the band have released,

Fig. 7 is a plan view of yet another embodiment of the device according to the invention similarly as in FIGS. 3 and 5, in which the superposed ends by means of an on pushing it and moved laterally back and forth pressure stempels successive rubbed and thereby heated and welded finally with each other, and

Fig. 8 is an enlarged scale partial section of Vorrich processing of Fig. 7.

According to Fig. 1 and 2, a housing block 1 is provided at one end face 2 with a back-up plate 3, the slide-shaped of two parts 4 and 5, which supported with ridges 6 and 7 in a continuous undercut guide 8 relative to each other are so that they can be moved from the retracted position shown in the drawing into the parting plane 9 of the plate 3 so that the two-part backing plate 3 is in the closed operating position.

Within the housing block 1 , an arm 10 is slidably guided along a longitudinal axis 11 , which lies in the division plane 9 of the backing plate 3 , relative to the backing plate 3 . A lever 12 , which can be adjusted by a drive (not shown), is articulated to the rear end of the slide-like or plunger-like arm 10 projecting from the housing block 1 .

On the lever 12 opposite end of the arm 10 , a cylindrical head 13 is mounted, which is rotatable about its central axis 14 , which is just in the division plane 9 of the backing plate 3 . Via a drive 15 , which is only indicated schematically, the head 13 can be set into rotary oscillation movements of low amplitude, oscillation frequencies of approximately 200 to 300 Hertz being provided.

In order to bring the cylindrical head 13 into the operating position, the arm 10 is moved along its longitudinal axis 11 by moving the lever 12 from its retracted position shown in FIG. 2 into the operating position against the inside of the two-part backing plate 3 . The arm 10 is provided with a wedge-shaped or conical section 16 , on which rollers 17 of two actuating levers 18 rest, which are each pivotably mounted within the housing block 1 about a fixed axis 19 .

Each adjusting lever 18 cooperates with an additional lever 22 via an adjusting screw 20 with a screwed lock nut 21 . Each of these further levers 22 is pivotally mounted about one of the two axes 19 . At the outer end, each lever 22 is provided with a jaw 23 which engages in a square bush 24 which is rotatably mounted on an axis 25 . This axis 25 is fastened in an elongated hole 26 , which is provided in each of the two parts 4 and 5 of the backing plate 3 .

When the head 13 is advanced into the operating position along the longitudinal axis 11 , the wedge-shaped or conical section 16 pushes the rollers 17 of the actuating levers 18 lying against it apart, as a result of which the actuating levers 18 are pivoted about the axis 19 assigned to them. This pivoting movement is carried on the lever 22 , which thereby push the parts 4 and 5 of the backing plate 3 towards one another. By means of the adjusting screws 20 , the He bel 22 are set so that the parts 4 and 5 of the backing plate 3 lie against each other with their respective leading edge 27 when the cylindrical head 13 is in its advanced operating position.

The parts 4 and 5 of the backing plate 3 are each provided with an arcuate recess 28 which corresponds to the curvature of the upper surface of the cylindrical head 13 so that the head 13 lies in the operating position within the recesses 28 and between the surface of the head 13 and the surfaces of the recesses 28 only a small gap remains, which corresponds approximately to the thickness of the interposed, superimposed ends of a band not shown here. The head 13 is then set into arcuate oscillating movements of low amplitude in order to generate the necessary heat in the ends of the thermoplastic tape lying one on top of the other and thereby bring about the welding of these ends by means of the contact pressure of the welding head 13 .

After completion of a welding process, the head 13 is pulled back. By means of return springs, not shown, the levers 22 are pivoted back into the starting position shown in FIG. 2, so that the parts 4 and 5 of the backing plate 3 move apart again into the starting position.

As soon as a new band has been placed around a container and tightened, the arm 10 is advanced again and the device is thus closed for a new welding.

From Fig. 3 and 4 it can be seen that the surfaces of the cylinder-shaped head 13 and the arcuate recesses 28 are each provided with a roughening 29 or 30 or a corrugation, so that between the head 13 and parts 4 and 5 of the Backing plate 3 located ends 31 and 32 of a band are each held in a short circuit on the surface of the head 13 and the recesses 28 in order to generate a relative movement between the ends 31 and 32 for heating these ends for a short time during the oscillating movements of the head 13 and to weld the heated strip ends together under a pressure indicated by an arrow 33 .

In this embodiment, the smallest necessary thickness 34 of the two parts 4 and 5 of the backing plate 3 is particularly small, so that the tape tension is only slightly reduced after the release of the welded ends 31 and 32 of the tape.

In the embodiment of the device according to FIGS. 5 and 6, the ends 31 and 32 of the band are not heated by relative frictional movements for the welding process, but by means of a heating tongue 35 , which is displaceably mounted in one part 5 of the backing plate 3 to be able to insert them between the band ends 31 and 32 . After the tape ends 31 and 32 are sufficiently heated, the heating tongue 35 is withdrawn, whereupon a pressure stamp 36 presses the heated tape ends 31 and 32 onto one another in order to bring about the desired welding. Then the welded tape ends 31 and 32 can be released after pulling back the parts 4 and 5 of the backing plate 3 .

Fig. 6 shows that the welded tape ends 31 and 32 are moved only a small distance after the parts 4 and 5 of the backing plate 3 have been moved apart, so that the tape tension also decreases only slightly, although the minimum thickness 34 Parts 4 and 5 of the backing plate 3 in this embodiment are larger than in the embodiment according to FIGS. 3 and 4.

In the embodiment according to FIGS. 7 and 8, the heat required for welding the band ends 31 and 32 is generated by a pressure stamp 37 , which in the horizontal direction according to a double arrow 38 in the direction of movement of the parts 4 and 5 indicated by arrows 39 and 40 the backing plate 3 can be moved swinging. Also in this embodiment, the plunger 37 is provided with a roughening 41 , just as the parts 4 and 5 and the backing plate 3 opposite the plunger have a roughening 42 , in order to achieve a frictional contact movement between the two band ends 31 and 32 to be able, however, to prevent these ends from moving relative to their support during the frictional contact movement.

In this embodiment as well, the smallest thickness 34 of parts 4 and 5 of the underlay plate 3 is greater than in the embodiment according to FIGS. 3 and 4, but it is nevertheless very small, as shown in FIG. 6 in connection with the embodiment according to FIG. 5 and 6 shows.

In the embodiments according to FIGS. 1 to 4 and 7 and 8, the frequency of the relative movements between the band ends 31 and 32 to be welded to one another is relatively low in contrast to previously known high-frequency ultrasound heating. This frequency is approximately in the range of 200 Hertz and particularly preferably in a range between approximately 200 and approximately 300 Hertz.

Claims (12)

1. Device for connecting the ends of tapes used in the setting of goods or the like, for example of tapes having thermoplastic material, with a removable plate serving as a support for the ends of the tapes lying on top of one another and with a plate movable over and against the plate End of the belts which can be placed on the plate, characterized in that the backing plate ( 3 ) is formed in two parts ( 4 , 5 ) and the head ( 13 ) is a rotating body which is mounted such that it can be swung back and forth about its longitudinal axis ( 14 ) is, or is a pressure stamp ( 36 ; 37 ). 2. Device according to claim 1, characterized in that the plate ( 3 ) is divided in the forward direction of the tapes and that its two parts ( 4 , 5 ) are laterally adjustable against each other and are mounted removable from each other. 3. Apparatus according to claim I or 2, characterized in that both parts ( 4 , 5 ) of the plate ( 3 ) are movably supported synchronously. 4. Device according to one of claims 1 to 3, characterized in that the plate ( 3 ) lying opposite the head ( 13 ) has an arcuate recess ( 28 ) into which the head ( 13 ) protrudes in its operating position. 5. The device according to claim 4, characterized in that when the backing plate ( 3 ) is closed, the deepest point of the depression ( 28 ) with the parting plane ( 9 ) of the two-part plate ( 3 ) coincides. 6. Device according to one of claims 1 to 3, characterized in that the plate ( 3 ) opposite the pressure stamp ( 36 ; 37 ) contains a rectangular recess into which the pressure stamp protrudes in its operating position. 7. The device according to claim 6, characterized in that the pressure stamp ( 37 ) parallel to the backing plate ( 3 ) is swingably mounted. 8. Device according to one of claims 1 to 7, characterized in that the recess ( 28 ) of the backing plate ( 3 ) and the head ( 13 ) or the plunger ( 37 ) with roughened contact surfaces ( 29 , 30 , 41 , 42 ) are provided. 9. Device according to one of claims 1 to 3, characterized in that in a part ( 5 ) of the backing plate ( 3 ), a heating tongue ( 35 ) in the recess ( 28 ) is mounted retractable. 10. Device according to one of claims 1 to 9, characterized in that the adjusting device for the head ( 13 ) or the pressure stamp ( 36 ; 37 ) with adjusting devices ( 17 to 25 ) for the two parts ( 4 , 5 ) of Plate ( 3 ) is coupled. 11. The device according to claim 10, characterized in that the actuating devices ( 17 to 25 ) for the two parts ( 4 , 5 ) of the divided plate ( 3 ) to operate synchronously with a common mechanical drive ( 10 , 12 , 16 ) are connected . 12. The apparatus of claim 10 or 11, characterized in that the adjusting devices ( 17 to 25 ) for the two parts ( 4 , 5 ) of the divided backing plate ( 3 ) contain an adjustment ( 20 , 21 ).