Apparatus for tightening,joining,and cutting off of plastic strips to girdle wrapped articles

The device for tensioning, joining and cutting plastic straps for packing articles is provided with a tensioning roller (17), sp. (13),. with which a movable friction jaw (47) is permanently connected, which is pressed against the ends (18, 19) of the tape connected to each other by friction. the heat generated by the oscillating movement of one end. (18) a tape carried by the friction jaw (47). The tensioner pulley (17) is coupled to the drive (13) via a loop spring clutch which is disengaged when the desired band tension is reached by a switching member (93) which is effective together with a presser (24) pressing the friction jaw (47) (18, 19) of the tapes and at the same time releasing the cutting member (81) by which the moving end (18) of the tape is cut, so that tensioning, welding and splicing of the tape ends (18, 19) are fully automatic.

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BACKGROUND OF THE INVENTION The present invention relates to a device for tensioning, joining and cutting plastic straps for wrapping articles, provided with a guide channel for the ends of the strap positioned in the housing of the device between the tensioning pulley connected to the drive. . a. support 7. a flat, at least one friction jaw, connected permanently to the drive, provided with a thrust member and mounted pivotably on an axis and simultaneously displaceably parallel to the support surface, and a cutting member also connected to the drive unit. ....... .

In the prior art tensioning and coupling devices for wrapping pre-packaged pre-packers. - ·. In order to achieve the necessary tension of the strap, the pressing member for the friction jaw must be actuated separately. In addition, a cutting member must be brought into the working position, which is generally fed by a lever or a switch and which then separates the end of the strip after the joint. With these known devices, the wrapping of the tape can be damaged during the wrapping of the articles thus carried out, which can then break during transport with the application of greater stress.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to overcome these disadvantages of known packaging devices and to solve the construction of a fully automatic tensioning device for honeycomb strips on which ...

the belt would be wrapped, the tape stretched, the ends joined together, and the ends separated. next '' '' '' .....⁷ equipment ky.

This finding is characterized in that a planetary gear set with a controlled loop spring clutch is arranged between the drive unit and the tensioning pulley, the switching element of which is connected to a projection on the housing of the device and a two-arm lever mounted on the housing, it is spring loaded and its second arm is provided with a thrust member having its thrust surface on the thrust roller on the friction jaws of the cutting member.

The main advantage of this solution is that the tensioner pulley automatically switches off when the desired tension value of the strap is reached, while the friction jaw is simultaneously moved into its functional position and the ends of the plastic strap are connected to each other under pressure and friction temperature. In this case, it is advantageous to use a timer for switching off the drive after a certain period of time, after which the localized softening of the ends of the strip and the mutual connection by welding are achieved .

According to a preferred embodiment of the device according to the invention, the loop spring clutch is provided with a loop spring which is guided around the bearing and / or the drive part and which bears at its other end on the switching member. This design · is easy to manufacture from simple components · commercially available and ensures reliable operation.

According to another advantageous embodiment of the device according to the invention, the sun gear of the planetary gear is connected to the drive unit and the carrier of the planetary gear is connected to the tensioning roller, the loop spring. _? . The coupling is arranged between the crown gear. around the planetary gear and the switching organ.

The loop spring is mounted around the cot of the new one. A planetary gear set. and with one end engages in a rotatably mounted annular switching member provided with a projection for actuating the two-arm lever and abutting the first projection on the spring element to determine the maximum torque transmitted.

The thrust member may be a thrust lever whose one end is connected to a tension spring and which is articulated on a two-arm lever. The two lever arms are connected to each other by a joint which, in the upright position of the arms, is reinforced by a stop on the housing of the device and keeps the pressure lever in its non-operating position. The second arm of the double-arm lever acts on the second extension of the switching member and can act on the second_and loose ...... end of the loop spring to loosen it when the joint at the end of the arms bends. ... Team. At the same time, the movable friction jaw of the strip section is inserted into its working position after insertion of the strips into its working position and the tensioning pulley and start of the device is fully automatic. operate by hand lever or switch.

In order to prevent the friction jaw from acting on the stretched and tensioned strip at the time of its unwinding after the drive has been started and at the time of tensioning, it maintains the push. In the idle position of the pressing member, the pressing surface engages the movable friction jaws at a distance from the ends of the strap.

For cutting off the excess part of the tape coming from the magazine, the device is according to. The invention has a cutting member movable perpendicular to the plane of the tape against the cut end of the tape and not displaceable in the direction of the tape axis under which one of the two ends of the tape is moved. This solution avoids damaging the other end of the strip wrapping the wrapped article during cutting, since the cutting member remains stationary relative to the other end of the strip. At the same time, the ends of the strip below the cutting member are reliably detached because they move relative to the cutting member by reciprocating movements which ensure the necessary relative movement of the object to be cut and the cutting edge necessary for a smooth cut. Preferably, the cutting member is curved into a circular arc, by which the ends of the strip are cut off during pivoting movements in two mutually opposite directions. During cutting, the cutting member is pressed by a compression spring to one end of the strip.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE TENSION, CONNECTING AND CUTTING EQUIPMENT FOR TAPE PROCESSING ENCLOSING THE WRAPPED ARTICLE, FIG. Fig. 3 is a partial vertical cross-sectional view of the device of Fig. 1, some parts of which are omitted for clarity;

III-III of FIG. 2, FIG. 4 is a partial vertical section through the plane of FIG.

IV-IV of Fig. 3 and seen from the rear, Fig. 5 is a horizontal section through the device of Fig. 4, taken along the line V-V in Fig. 4; Fig. 6 shows a partial section through the device of Fig. 2; plane VI-VI, Fig. 7 is a partial plan view of the apparatus of Fig. 1, the tensioning and operating lever of which is omitted and shown in the direction of arrow VII in Fig. 2; FIG. 2 is an enlarged view of FIG. 9 is a partial view of part of FIG. 2, in which the end of the tape guide is shown on a larger scale.

The device according to the invention is shown in the examples in the form of a hand-held device 10 for tensioning, interconnecting the ends and cutting off the plastic tape during wrapping of wrapped articles, whose front part 11 contains aggregates for tensioning, closing and cutting the plastic tape wrapped around and in the rear part 12 there is a drive 13 and electrical switching and operating elements. All the components are housed in a housing 14, over which a hand lever 15 is mounted in the longitudinal direction of the apparatus 10, by which the support plate 15 can be released and lifted from the tensioner pulley 17 so that both tape ends 18, 19 can be inserted into the guide channel 20 Between the tensioner roller 17 and the support plate 16 from the front, i.e. from the left in FIG. When inserting the tape, the guide lever 21 is raised upwards; the guide lever 21 is adjustable in a direction perpendicular to the longitudinal axis of the apparatus 10 and allows the processing of the strapping tapes of different width.

Inside the hand lever 15 there is a thrust lever 22 which is pivotable and acts on the upper end 23 of the thrust member 24, which will be described in more detail below, and by which the movable friction jaw can be brought back to its initial position , as will be described in more detail below.

On the upper side of the housing 14 there is a switch 25 by which the actuating mechanism of the drive 13, which is not described in detail here, can be switched on.

The tensioner pulley 17 is firmly against the upper end 18 of the tape which is pushed by the backing plate 16 against the tensioner pulley 17 and is pulled backward by the tensioner pulley 17 in the direction of arrow 26, during which pulling pulley 17 rotates in the direction of second arrow 27. The tensioner roller 17 is rotatably mounted in the front part 11 of the apparatus 10 in the housing 14 (FIG.

5) and is kept rotating by a worm drive 28 whose worm wheel 29 is arranged on the shaft 30 of the tensioner pulley 17 and is driven by a worm 31 which is housed in the housing 14 in the longitudinal direction (FIG. 4) and the worm shaft 32 is rigidly connected to the carrier 34 of the planetary gear 35 by its rear end 33 '. The planet carrier 34 houses a planetary gear 36, or several planetary gear 36, which engage the crown gear 37 and the sun gear 38, which is mounted on the output shaft 39 of the drive gear 40 whose drive shaft 41 is connected via a clutch 42 to the drive 13 [FIG. 5).

On the drive shaft 41, which is housed in the housing 14 · parallel to the output shaft 39 · and which carries a pinion 43 which engages a gear mounted on the output shaft 39, is additionally mounted rotatably an eccentric 45 which drives The connecting rod 46 has a movable friction jaw 47 which is located above the tape guide channel 20 on the front of the apparatus 10 and which is pivotable in two mutually opposite directions about the axis 48 in the direction of the arrow 49 (FIG. 5).

As can be seen in FIG. 2, the longitudinal section of the friction jaw 47 is substantially H-shaped and surrounds with its two front legs 50, 51 a housing block 52 which is part of the housing 14 and also has a vertical an axis 48 around which the friction jaw 47 can not only perform pivotal movements, but can also move up and down in the longitudinal direction and within certain limits. Sufficient clearance is provided between the bearing block 52 on one side and the front legs 50, 51 of the movable friction jaw 47 to allow these vertical displacements.

On the rear face 54 of the H-shaped friction jaw 47 is rotatably mounted between the two rear legs 56, 57 of the pressure roller 58, which is formed by a ring mounted on a ball bearing, as best seen in Fig. 6. 58, the aforementioned pressure member 24, comprising a pressure lever, is pivoted at its lower end 59 about a pin 60 in the housing 14. In addition, the pressing member 24 has at its lower end a protruding pressing surface 61 which engages the upper rear arm 56 above the rear face 54 of the movable friction jaw 47 and keeps them in its upper non-operating position in which the guide channel 20 remains free and which does not act on the ends 18, 19 of the tape.

At its upper end 23, the thrust member 24 is connected by means of a hinge pin 62 to the first arm 63a of the two-arm lever 63, the second arm 63b being pivotably mounted on the horizontal pivot axis 64 in the housing 14. a tension spring 66, which is fixed to the housing 14 and which tries to pull the front end 65 of the two-arm lever 63 downward, thereby pivoting the two-arm lever 63 about a horizontal pivot axis. 64 counterclockwise. The two arms 63a, 63b of the two-arm lever 63 are connected to each other by a hinge 67 which can abut a stop 68 in the housing 14. When the second arm 63b is pivoted. counterclockwise, the hinge · 67 moves slightly upwards until it reaches the stop 68 and is reinforced on its upper side.

The hinge pin 62 retains a strong tension spring 69, which extends in the groove 70 of the housing 14 substantially horizontally and is fastened in its housing end 14 in the housing 14 of the device (FIG. 7). The strong tension spring 69 tries to pivot the pressure. counterclockwise, but the two-arm lever 63 prevents this when it is in the position shown in FIG. 2 in which the hinge 67 is supported against the stop 68.

It can be seen from FIG. 2 that a further lever 171 is articulated to the front horse 65 of the lever arm 63, which is articulated to a rocker arm 72 that can swing about the rocker arm 73 housed in the housing 14 and pushes with its rear crank end. 74 to one end 75 of the loop spring 94 which extends through the longitudinal opening 76 in the intermediate wall 77 of the housing 14 into the areas of the rocker arm 72; the function of the loop spring 94 will be explained in the following.

Referring to FIG. 2, at the rear end of the front portion 11 of the apparatus 10, a knife guide block 78 is mounted above the guide channel 20 for guiding the tape, in which a guide sleeve 79 carrying a knife holder 80 at its lower end is mounted. the cutting side 81 of which, for example, a leaf knife, is fastened by means of a screw 82. The blade of the cutting member 81 is formed in the form of a portion of the cylindrical surface and is curved into a circular arc whose center lies in the vertical axis 48 of the movable friction jaw 47.

The knife guide housing 79 is provided with a blind hole 84, open upwardly, in which a compression spring 85 is provided, which is supported at one end by the bottom of the blind hole 84 and the other end abuts the upper bottom 86 of the knife block 78. attempts to push the knife guide bush 79 downward with the knife holder 80 of the cutting member 81. A compression spring 85 surrounds a tension rod 87 which is mounted in the lower portion of the knife guide sleeve 79 extends through the upper bottom 86 of the knife guide block 78 and is articulated at its free end to an actuation formed in the form of an angle lever 88 supported by a tapered end 89 its second free arm 90 against the rear edge of the pressure member 24.

It can be seen from FIG. 2 that the control member 88 is trying to pull the guide sleeve 79 and its knife holder and cutting member 81 against it in its position shown in FIG. applying an upward compression force of the spring 85 to maintain the cutting member 81 in its idle position.

Figures 3 and 4 show that the ring gear 37 on the worm shaft 32 is rotatably mounted on the worm shaft 32 by means of an annular flange 91 which is spaced at a certain distance by an annular flange portion 92 of the annular switching member 93 which is mounted on the worm shaft 32 is also rotatable. A loop spring 94 of the loop spring clutch is wound on the ring flange 91 of the ring gear 37. whose rear end 75 extends through the aperture 76 of the partition 77 into the adjacent space and abuts the crank end 74 of the rocker arm 72, as previously described. The other rear end 95 of the loop spring 94 is rigidly connected to the annular switching member 93 (FIG. 4),

It can be seen from Fig. 3 that the switching member 93 is provided with a first projection 96 extending in a radial direction from its axis and a second projection 97 located on its opposite side. The first projection 96 of the switch member 93 extends into the recess 98 of the housing 14 and abuts one end 99 of the spring element 100, which in the illustrated embodiment is a compression spring supported on its opposite end 101 by a support 102 supported by the adjusting spindle 103. which is screwed by its upper threaded end 104, which passes through the housing 14, into the adjusting nut 105, which adjusts the tension of the spring element 100.

The second projection 97 of the switch member 93 extends through the opening 106 in the intermediate wall 77 of the housing 14 into the groove 70 and engages below the second arm 63b of the two-arm lever 63 located in front of the horizontal pivot axis 64.

In order to allow the tape ends 18, 19 to be easily inserted into the guide channel 20, in which the tape is then firmly gripped without preventing lateral displacement of the upper tape end 18 relative to the lower tape end 19, a blind hole 109, 110 is formed on both sides of the guide channel 20 by means of a guide channel 20, covered by the intermediate space 108, in which rolling elements 112, in particular balls, loaded with compression springs 111 are arranged. In this case, rolling elements 112 protruding partially from the blind holes touch the opposing surfaces 113, 114, each facing the guide channel 20 and limiting it from the top and bottom, i.e. the rolling elements 112 disposed in the base plate 107 are pressed against the bottom surface 113 108, while the roller bodies 112 located in the blind holes 110 of the intermediate plate 108 are pushed by the compression springs 111 against the upper opposite surface 114 of the base plate 107.

From Fig. 2, but better still from Figs. 8 and 9, the rolling elements 112 are each arranged in pairs adjacent the ends 18, 19 of the band and that the lower pair 112a of the rolling elements 112 disposed in the base plate 107 is disposed in the base plate.

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10 the longitudinal direction of the strip at a distance from the upper pair 112b of the roller bodies 112 located in the intermediate space 108.

The operation of the device according to the invention is as follows:

After wrapping the strap around the wrapped object (not shown) and inserting the ends 18, 19 of the strap into the guide channel 20 from the front of the device and before inserting the backing plate 16 away from the tensioner pulley 17 by hand 15, the hand lever 15 is released. 16 presses the two ends 18, 19 of the tape onto the tension roller 17. Then, by means of the switch 25, the drive 13 is switched on by means of a switching device (not shown).

The rotating drive shaft 41 then pivots the movable friction jaw 47 through its connecting rod 46 to its raised position as shown in Fig. 2 and moves it in two opposite directions by oscillating movements, in which position the upper rear leg 56 of the friction jaw 47 is supported on Thus, in this position, the movable friction jaw 47 does not come into contact with the tape ends 18, 19 which are located below, but moves freely above them.

At the same time, the sun gear 38 is driven by the drive gear 40, which drives the sun gear 36. The sun gear 37 of the planetary gear is firmly held by the loop spring 94 and the initially stationary switching member 93 so that the sun gear 36 rotates in the inner gear of the sun gear. 37 and rotates the worm shaft 32 which is rigidly connected to the gear shaft. of the satellite 36, and which then drives via the worm gear 29 the shaft 39 of the tensioner pulley 17, which then rotates and the upper end 18 of the wrapper wrapping tape moves in the direction of arrow 25 and thereby applies tension to the wrapper wrapping tape the lower end 19 of the tape is held firmly by a measure (not shown) in the apparatus according to the invention.

When the band tension reaches the value set on the spring element 100, the torque transmitted from the ring gear 37 via the loop spring 94 to the switching member 93 exceeds the force of the spring member 100 on which the first projection 96 of the switching member 93 is mounted. the switching member 93 begins to rotate clockwise (FIG. 3), as indicated by the arrow 115. Rotation of the switching element 93 results in lifting of the second projection 97 of the switching element 93 and lifting of the front end 65 of the double-arm lever 63 (FIG. 2) against the action of the tension spring 66. its support at the upper end and the strong tension spring 69 (FIG. 7) can exert its action, which pivots the pressing member 24 in a counter-clockwise direction. In doing so, the pressing surface 61 releases the movable friction jaw 47 and the lower end 59 of the pressing organ 24 begins to press on the pressing roller 58 mounted on the rear face 54 of the movable friction jaw 47. The movable friction jaw 47 is still maintained in the oscillating drive. the back and forth of the tape 18, which carries it as it oscillates about the vertical axis 48 in two opposite directions with simultaneous lever pressure by the pressure member 24. During these relative movements of the tape ends 18, 19, the frictional heat is produced by a known phenomenon, which results in the softening of the superposed parts of the surfaces of the tape ends 18, 19, so that a fusion weld can be achieved if the friction jaw 47 is maintained Pressed.

If the thrust member 24 is swung forward by the force of the tension spring 69, the control member 88, which rests on its rear side, swivels along with it. The guide sleeve 79 and the knife holder 80 associated therewith are released and the compression spring 85 is pressed downwards until the head 83 of the screw 82 abuts the upper surface 85 'of the recessed recess 84 * of the lower rear arm 57 of the movable friction jaw 47. Since the upper end 18 of the tape moves in mutually opposite directions perpendicular to the longitudinal axis of the tape, under the now lowered cutting member 81, this moving play end 18 is cut off while the stationary lower end 19 remains intact. ,

If the pressure member 24 pivots counterclockwise forwards, the switch 116 is released, which has been depressed and held in the idle position by the end 23 of the pressure member 24. This switch 116 turns off the time switch that keeps the drive 13 in operation for a period of time, which time is set to frictional. The jaw 47, pressed against its upper end 18 of the tape as it oscillates, was sufficient to generate sufficient frictional heat in the mating faces of the mating ends 18, 19 of the tape to soften and bond the mating faces.

Simultaneously with the pivoting of the double-arm lever 63, the rocker arm 72 is also rotated clockwise by the action of the other lever 171, its cranked end 74 pressing against one end 75 of the loop spring 94. The loop spring clutch releases so that the crown gear 37 can rotate freely on the worm shaft 32. The sun gear 38 of the planetary gear 35 then drives the crown gear 37 and the planetary carrier 34 and the worm drive 28 associated therewith via the gear satellite 36.

As soon as the time interval set on the timer has elapsed, the drive 13 is switched off by means of a switching device (not shown) with the control circuit.

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Weld by the pressure member 24 on the friction jaw 47, is retained. In this case, the tightly pressed strip ends 18, 19 can be welded together in the region where the heating and softening have taken place and can thus be firmly connected.

The hand lever 15 is then pressed. the support plate 16 can be moved away from the tensioning. the pulleys 17 and the handpiece 10 can be removed laterally from the formed loop wrap. Here, the rolling elements 112. it pushes into the blind holes 109, 110 so that the wrapping tape can slip forward from the guide channel 20.

When the hand lever 15 is depressed, the pressure lever 22, which is pivotably attached to the upper end 23 of the pressure member 24, presses it against the action of the tension spring 69 to the initial position shown in FIG. at the same time, the control member 88 is pivoted and the cutting device is retracted.

In addition, the upper end 23 pushes the actuator 88 again against the switch 116 and returns it to its initial position.

The invention is not limited to the illustrated embodiment, but it is possible to make several modifications and additions that fall within the scope of the invention. As already mentioned, instead of a loop spring clutch, it is possible to use magnetic clutches, ratchets with gears. - pneumatic or hydraulic couplings - etc. for detaching the tensioning wheel from the drive unit while operating the pressure member. It is also possible to use other tensioning devices, for example a thong-tensioning device, or the device may be provided with hydraulic pressure members instead of a thrusting lever to compress the movable friction jaw.