EP0894718B1 - Device for introducing a strap in a strapping machine - Google Patents

Description

The invention relates to a belt sliding device Strapping device for putting a strap around a packaged product, as well as the one provided with a belt sliding device Strapping.

To put on a tape around a good to be packed A variety of strapping machines have already become known. Although these machines are structurally strong at times different from each other, they have in common that they each have a belt sliding device with which the Tape pulled from a supply roll and the feed of the Tape to form a tape loop around the packaged goods becomes. After the band loop is formed, the band must tightly applied to the packaged goods. To generate the the tape tension required for this will be the tape as long withdrawn until the required tape tension is applied is. This process is usually also done the belt slide device used.

In the known belt sliding devices can basically two types can be distinguished. In the first type the tape is over a circumferential belt of a belt or enveloping drive. The belt is thereby caused by frictional forces between the belt and the belt. In which The second type of belt pusher is a feed of the volume achieved by directly over a or several roles is performed. Again, there is a frictional force - namely between the roles and the belt - used.

The present invention relates to the first type of belt sliding devices, which for example from the CH-PS 662 791 is known. There is a strapping device with described a belt sliding device in which a belt is guided over a deflection roller and a drive roller. So one for feeding and tensioning the belt required friction between the belt and the belt comes about, an eccentric disc presses the tape against the Belt. Has been particularly advantageous with this device shown that the tape is not only in the area of Wrap angle of the belt on the pulley. Due to the eccentric disc, it turns up on the pulley on the one hand, a larger wrap angle of the belt. In addition, the eccentric disc also causes the tape already outside the range of the wrap angle on Belt rests, which creates a relatively large contact surface between the belt and the band. This guy of belt sliding devices is therefore predestined for the application of particularly high clamping forces.

Despite these advantages, the arrangement cannot be complete satisfy, especially because of the redirection of the belt through the eccentric disk belt deformations can result. These band deformations are automated Strapping of packaged goods with straps in particular disadvantageous because they guide the tape properly difficult if not during the formation of the tape loop even prevent. Such band deformations can Automated strapping machines come to a standstill. To put the machine back into operation after standstill take and then a perfect function usually grant the deformed band section removed as a committee.

The invention is therefore based on the object of a belt sliding device of the type mentioned at the beginning, as well as a Strapping device - the one with a strap pusher is provided - to further train that the danger the emergence of such band deformations at least is reduced.

This task is accomplished by a Belt sliding device according to claim 1 solved.

The task is also carried out by a strapping device solved according to claim 15.

An essential aspect of the invention is therefore that for the tension phase - i.e. the time span in which the tape tension is applied to the tape at which the Band is subsequently closed - a separate tensioning wheel is used. The measure, for generation a feed rate of up to 4 m / s and the application of the Clamping force to use a different wheel each allows the tensioning wheel to the belt only during the tensioning phase to apply. As a result, the tape only lies flat on the envelope member, for example a V-belt, and also experiences a deflection by a tensioning wheel only if it is actually is excited. Band deformation due to a die Wheel creating tension in the belt - like through the eccentric disc from CH-PS 662 791 - can thus essentially can be avoided, especially when the strapping device is at a standstill not the feared "memory effect" established. It has been shown that a essential cause for band deformations a longer lasting Wrapping a wheel or a roller through the Band at high band tension. The tape takes this permanently a shape that its course in the belt sliding device equivalent.

In preferred embodiments of the invention, this can Tensioning wheel can be transferred to two end positions, this being the case conveniently done by a pivoting movement. In The first end position is the tensioning wheel at a distance from the belt and arranged to the belt so that between the tensioning wheel and the Band does not come into contact. In the second end position, which the tensioning wheel only occupies in the tensioning phase will Tensioning wheel pivoted in the direction of the belt, so that a partial wrapping of the tensioning wheel through the belt and gives the strap.

It has proven to be advantageous if the tensioning wheel itself is not driven. The one required for tensioning Rotational movement of a belt can be convenient generated by the first drive wheel.

In further expedient embodiments of the invention the belt sliding device has a second drive wheel that can be placed in a position where it presses against an outer surface of the enveloping member or belt and is partially embraced by it. The second Drive wheel can be used to generate the feed movement of the Belt, i.e. the movement with which the belt pulls the tape from a supply roll to education a belt loop to enable the packaged goods. It is however preferred that the second drive wheel additionally also to generate the for a withdrawal movement of the Band required rotation of the enveloping member used becomes. In this context, it may be useful exclusively for both the feed and retraction movements to use the second drive wheel. Furthermore can be provided, the second drive wheel only for this use both movement.

In further advantageous embodiments of the invention is the second drive wheel with a contact pressure, which is preferably generated by a spring against the belt on. In addition, the second drive wheel is pivoted, without locking it in a specific position. Because the strap is also not between one on the other Side of the belt arranged counter wheel, such as the deflection wheel, and the drive wheel is pinched, results the position of the second drive wheel in dependence from the belt tension. The second drive wheel thus has also functions as a belt tensioner.

In order to obtain the best possible friction, lies in a further preferred embodiment of the invention Pinch roller both in the feed, retraction and in the tension phase on the belt and presses it onto one of the two wheels, preferably on a non-driven one Guide wheel.

Further preferred configurations of the invention result itself from the dependent claims.

Fig. 1

eine Umreifungsvorrichtung in einer Seitenansicht, mit einer erfindungsgemässen Bandschiebeeinrichtung;

Fig. 2

die Bandschiebeeinrichtung aus Fig. 1 während einer Vorschub- und Rückzugphase;

Fig.3

die Bandschiebeeinrichtung aus Fig. 1 während einer Spannphase.

The invention is explained in more detail with reference to the exemplary embodiments shown schematically in the figures; show it:

Fig. 1

a strapping device in a side view, with a strap sliding device according to the invention;

Fig. 2

1 during a feed and retraction phase;

Figure 3

1 during a tensioning phase.

Fig. 1 shows a highly schematized automated Strapping device 1 with which a plastic strap 2 withdrawn from a supply roll 3 and in a guide 4 around a packaged item 5 is placed. 1 the plastic band 2 already loosely surrounds the packaged goods 5 a loop 6.

A band pushing device 7 of the strapping device 1 performs both the feed, retraction and tensioning of the Volume 2. After the target tension is applied to the tape the tape is moved from one in the feed direction (corresponds to arrow 8) of the belt behind the belt sliding device 7 arranged closing unit 9 by friction welding closed and the loop 6 separated from the tape 2. Of course, the ends of the Band loop 6 also by any other Connection technology can be connected.

It can be seen in FIG. 2 that the belt sliding device 7 an enveloping drive 12 with a multiple V-belt 13 Has envelope member. The V-belt 13 runs with its inner surface 14 via two wheels 15, 16 with different Diameters. Here the smaller wheel is on first drive wheel 16 for the belt, which is not one DC motor shown driven by a spiroid gear becomes. The larger wheel is a non-driven, free running deflection wheel 15, with which the band 2 of its direction with which it is in the belt sliding device runs in, deflected towards the closing unit 9 becomes. To make changing the belt easier and for adjustment the belt tension is the distance between the Deflection wheel 15 and the drive wheel 16 in a not shown Modifiable, e.g. in which the deflection wheel on a pivot lever is arranged.

To generate the feed and retraction movement, the Belt slide device 7 one of one also not shown DC motor driven second Drive wheel 17 on. The second drive wheel 17 is on one lever 19 pivoted about an axis 18 and is by a spring, not shown, against an outer surface 20 of the belt 13 pressed. This wraps around the belt 13 a portion of the circumference of the second drive wheel 17, causing this to rotate on the belt 13 transfers.

A non-driven pressure roller 23 is with its axis arranged at one end of a further lever 24. The in lever 24 running approximately along an arc is on his other end 25 pivotally mounted, so that between the lever 24 and the deflection wheel 15 forms a gap in which the belt 13 and the band 2 runs. In addition, the pressure roller 23 by a not shown Spring pressed in the direction of the deflection wheel 15. Consequently the pressure roller 23 presses the band 2 onto the outer surface 20 of the belt. The contact pressure of the pressure roller 23 is Cause of the creation of a feed Frictional force between the belt 13 and the belt 2. The place at which the essentially linear contact between the pressure roller 23 and the belt 2, is located on the one hand in the area in which the belt the pulley 15 wraps around. On the other hand, the pressure roller presses 23 at a point on the tape 2 at which the tape lifts off the belt 13 and approximately tangentially from the deflection wheel 15 runs away.

Furthermore, the pressure roller 23 is provided with a not shown Provide sensor with which their speed, at least however, their rotational state is detectable. When the Pressure roller 23, the sensor sends a corresponding signal to a central control of the, also not shown Strapping.

As can be seen from FIGS. 2 and 3, the belt sliding device has 7 a freely rotatable tension wheel 26, the also on a lever 28 pivotable about an axis 27 is arranged. The tensioning wheel can be moved through the swivel lever 28 be transferred to two end positions. In the shown in Fig. 2 the first end position is the tensioning wheel 26 at a distance from Volume 2 arranged and has no contact with it. By a pivoting movement of the lever 28 is the tensioning wheel 26 in the second end position shown in Fig. 3 convertible, in which presses the tensioning wheel 26 against the belt 13, so that both the band 2 and the belt 13 the tension wheel 26 partially wrap around its circumference. The part of the Belt 13, which wraps around the tensioning wheel 26, lies freely between the two wheels 15, 16, without these to lie on or between these and the tensioning wheel 26 getting pinched. Swiveling the tensioning wheel 26 thus causes the belt 13 and the band 2 to experience additional redirection. As a result, the tape is 2 along the belt for a longer distance than in the comparison to the feed and retraction phases described above. In with respect to an (imaginary) straight line connecting the axes of the the two wheels 15, 16 is the tensioning wheel 26 in this second end position approximately at the middle of the Connecting line. The second drive wheel 17 is located with regard to the straight line mentioned on the other side, but also about the height of the middle this straight line and thus opposite the tensioning wheel.

By pivoting the tensioning wheel 26, the Belt tension increased. This causes the belt 13th the second drive wheel 17 against that acting on the lever 19 Spring force - in the direction away from the tensioning wheel 26 - presses. As a result, the wrap angle of the Belt on the second drive wheel 17 during the tensioning phase. The second drive wheel also acts like a belt tensioner, with which a predetermined belt tension is set can be.

To the movements of the individual elements of the belt sliding device to generate are the first and the first second drive wheel 16, 17 each with a separate own drive motor (not shown). In addition, the strapping device according to the invention 1 a likewise not shown in the figures, further - designed as a DC motor - Drive motor with which the pivoting movement of the lever 28th of the tension wheel 26 is generated.

Both the drive motors of the drive wheels 16, 17 and the drive motor of the swivel lever are controlled by a parent central control of the strapping device 1 driven.

To generate the feed of the tape, the second one Drive wheel 17 driven by its DC motor, so that it rotates clockwise, as shown in Fig. 2 by the Arrow 29 is indicated. A frictional connection between the Drive wheel 17 and the belt takes the latter, which turns it counterclockwise. Since the Belt 13 with a certain tension on the two wheels 15, 16 sits, these are carried along by the belt movement. As has already been explained, the pressure roller 23 presses the band 2 against the belt, which essentially in Area of the pressure roller 23 also a friction between the belt and the belt 13 is generated. This friction causes the feed (arrow 8) of the band 2 to form the Belt loop around the packaged goods 5 in the guide 4 (FIG. 1). As soon as the end of the tape from the guide 4 back into the Capping unit 9 enters and there one as a limit switch trained stop (not shown) is actuated the drive motor of the second drive wheel 17 is switched off and clamped the tape end. To a particularly quick one To achieve this engine comes to a standstill Counterflow braked.

After this feed phase has ended, the belt surrounds it Packaged goods 5 loose, i.e. it surrounds the packaged goods without closing them touch. In the subsequent withdrawal phase, volume 2 withdrawn against the direction of arrow 8 to it create the packaged goods 5. The withdrawal phase begins with the Switch on and reverse the direction of rotation of the second drive wheel 17. The second drive wheel 17 thus rotates during the retreat phase counterclockwise, which is shown in Fig. 2 is indicated by the arrow 30. The pressure of the pinch roller 23 on the belt now causes the belt to come off the belt is pulled back towards the supply roll 3 until it is on Packaged goods are present. The withdrawal movement ends when the tape is provided with a clamping force that is greater than that Frictional force between the belt 13 and the belt 2. Is this Condition reached, both the tape and the pinch roller remain 23 stand and the strap slips under the belt.

As soon as the pressure roller sensor detects that it is at a standstill , the control system causes the Tensioning wheel 26 from its first to its second end position (Fig. 3), whereby the tensioning phase is initiated. The Tension phase is characterized by the fact that the tape with only withdrawn a relatively short length of tape and in essentially the band tension is increased.

Simultaneously with the pivoting of the tensioning wheel 26 Motor of the second drive wheel 17 turned off and that first drive wheel 16 with a clockwise direction of rotation (Arrow 31) driven. Here, the pivot lever 28 is actuated a mechanical tooth coupling, not shown, with the the first drive wheel coupled to its drive motor becomes. The gear coupling points on the side of the drive wheel 16 an internally toothed gear and on the side of the Drive motor an externally toothed pinion. So that Teeth of the pinion the corresponding tooth gaps of the gear the electric motor turns the pinion already in this process. Compared to the previously known Belt sliding devices for the engagement of moving elements on drive motors so far often usual electromechanical friction clutches occurs this clutch has almost no wear. Furthermore very high clamping forces can be achieved with these coupling types of up to 4000 N.

The for the application of a clamping force of up to 4000 N. required friction between the belt and belt can one by the compared to the second drive wheel 17th generates larger diameter of the first drive wheel 16 which allows greater torques. On the other hand the belt experiences an additional tension wheel 26 Redirection, which means that it also over a longer distance Belt is tight. The one that can be transferred from the belt to the belt This increases the frictional force. Finally, the height the clamping force by a torque control of the Drive motor of the first drive wheel are limited. There the drive motor of the second drive wheel during the Tensioning phase is switched off, the tensioning wheel runs during the Clamping process freely with.

After the target clamping force is reached, the closing unit comes 9 used. In this is now the Place the tape 2 clamped, which is connected to the tape end shall be. After the drive motor of the first Drive wheel 16 is turned off, the belt loop with welded to the end of the strip and separated from the supplied strip 2.

After the tape is clamped in the capping unit, the control system causes the tensioning wheel to be transferred again 26 from its second to its first end position. Thereby lifts the tensioning wheel 26 from belt 2 and relieves it. Thus, the tape has - after the tensioning phase has ended Start of the next feed phase - only in the area of the Pressure roller 23 has a substantially linear contact with the belt 13. This can cause permanent band deformation be avoided due to the "memory effect".

Claims (15)

1. A band-moving device of a strapping device for applying a band (2) around a package, comprising:

   an enveloping drive (12) having only one enveloping component and at least two wheels (15, 16) engaging an inner surface (14) of said component, at least one of said two wheels (15, 16) being designed as a drive wheel (16) operatively connectable with a drive motor to drive the enveloping component (13),

   a pressure pulley (23) for pressing the band onto an outer surface of the enveloping component to produce, between the band (2) and the enveloping component, a frictional force to move the band in one direction,

   a mechanism to reverse the direction of rotation of the enveloping component (13), so that the band (2) can be moved both in a feeding direction and in a tensioning direction, and

   another tensioning wheel located opposite the outer surface (20) of the enveloping component, designed as a tensioning wheel (26) for pressing the band (2) onto the enveloping component, during a tensioning phase, in order to apply a band tension, characterised in that the pressure pulley (2, 3) is arranged in a region in which the enveloping component (13) wraps around one of the two wheels (15, 16) to thereby press the enveloping component (13) against one of the two wheels with the pressure pulley (23).
2. The band-moving device as claimed in Claim 1, characterised in that the tensioning wheel (26) is moveable into two end positions, whereby the tensioning wheel (26) is arranged at a distance from the enveloping component when in the first end position, and the enveloping component partly wraps around the tensioning wheel (26) when the tensioning wheel is in the second end position.
3. The band-moving device as claimed in one or both of the foregoing claims, characterised in that the tensioning wheel (26) is pivotably hinged on a lever (28).
4. The band-moving device as claimed in one or more of the foregoing claims, characterised by a second drive wheel (17) for engaging the outer surface (20) to drive the enveloping component.
5. The band-moving device as claimed in Claim 4, characterised in that the position of the second drive wheel (17) can be varied with respect to the position of the first drive wheel (16).
6. The band-moving device as claimed in Claim 5, characterised in that the second drive wheel (17) is pivotably mounted on a lever (19), and in that the second drive wheel (17) can be pressed onto the enveloping component, particularly by means of an elastic spring which is arranged to act on the lever (19).
7. The band-moving device as claimed in one or more of the foregoing Claims 4 to 6, wherein, during a feeding phase in which the band is subjected to a feeding motion by being pulled from a delivery spool, only the second drive wheel (17) drives the enveloping component.
8. The band-moving device as claimed in one or more of the foregoing claims, characterised in that, during a tensioning phase in which the band is pulled back counter to the feeding direction in order to apply the band tension, the enveloping component can be driven only by the first drive wheel (16).
9. The band-moving device as claimed in one or more of the foregoing Claims 4 to 8, characterised in that the pressure pulley (23) is provided with a sensor which monitors the state of rotation, particularly a standstill position, of the pressure pulley (23), the sensor sending a signal to a control unit indicative of a specific state of rotation, in particular a standstill position, of the pressure pulley, whereby the control unit switches off a drive motor of one of the drive wheels (16, 17) and the control unit then causes the tensioning wheel (26) to be pressed against the enveloping component and to generate a drive motion of the other drive wheel (16, 17).
10. The band-moving device as claimed in one or more of the foregoing claims, characterised in that the pressure pulley (23) is arranged in that region of a wrap angle by which the enveloping component wraps around the guide wheel (15), and in that the pressure pulley (23) presses the band against the enveloping component and thereby presses the enveloping component against the guide wheel (15).
11. The band-moving device as claimed in one or more of the foregoing claims, characterised in that the enveloping component is a V-belt (13).
12. The band-moving device as claimed in one or more of the foregoing claims, characterised in that to prevent excessive band feeding a drive motor can be braked using countercurrent.
13. The band-moving device as claimed in one or more of the foregoing claims, characterised in that the pressure pulley (23) rests on the band in a feeding phase, a pulling-back phase and in a tensioning phase.
14. The band-moving device as claimed in one or more of the foregoing claims, characterised in that the tensioning wheel (26) is engaged with the enveloping component only during the tensioning phase.
15. A strapping device for hooping a package with a band, in particular a plastic band, characterised by a band-moving device (7) as claimed in one or more of Claims 1 to 14.

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