EP0894718A1 - Device for introducing a strap in a strapping machine - Google Patents

Abstract

The arrangement has an envelope drive with only one envelope element or V-belt (13) with its surface passing over two wheels, at least one a drive wheel able to be driven by a motor to drive the V-belt. The band (2) is pressed against the surface of the V-belt by a pressure roller to generate friction between the band and V-belt which moves the band in one direction. The pressure roller is deployed where the envelope element passes round one of the wheels and presses the V-belt against the wheel. The direction of rotation of the V-belt can be reversed so that the band can be moved in feed and tensioning directions. A clamp wheel (26) opposite the outer surface of the V-belt applies band tension to the V-belt during a band tension phase.

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 device.

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 is pulled from a supply roll and the feed of the Tape to form a 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 To generate the the tape tension required for this will be the tape withdrawn until the required tape tension is applied is. This process is usually also used used the belt sliding device.

In the known belt sliding devices can basically two types can be distinguished. In the first type the belt is over a circumferential belt of a belt or Envelope drive led. 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 tape is achieved by directly or several roles is performed. Here too 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 demonstrated that the tape is not only in the area of Wrap angle of the belt on the pulley. Because of 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 area between the belt and the band. That 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 in the automated Strapping of packaged goods with straps in particular disadvantageous because they guide the tape properly if not difficult 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 will 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 object is achieved by an Strap shifting device of a strapping device for Put on a tape loosened a packaged goods, which with a Envelope drive is provided, which is only an envelope member has that with an inner surface over at least two Wheels is guided as at least one of the two wheels Drive wheel is formed with a drive motor in Active connection can be brought, whereby the envelope member is drivable, the tape by a pressure roller on a Outer surface of the enveloping member can be pressed in order between the Band and the enveloping member to generate a frictional force which is slidable in one direction, the Pinch roller is arranged in an area in which the Envelope member wraps around one of the two wheels, whereby with the Pinch roller the envelope member against one of the two wheels can be pressed, means for reversing the direction of rotation of the Envelope are present, so that the tape in both Feed as well as in a clamping direction is movable, and another, the outer surface of the envelope member opposite wheel is present, which as a tensioning wheel is formed, the band during a tensioning phase Applying a tape tension to the envelope member presses.

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 create. As a result, the tape only lies flat on the envelope member, for example a V-belt, and also experiences a redirection by a tensioning wheel only if it is actually is excited. Band deformation due to a 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" sets. 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 follows its course in the belt sliding device corresponds.

In preferred embodiments of the invention, this can Tensioning wheel can be transferred to two end positions, this being the case expediently carried out 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 wrap 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 envelope 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 Deflection wheel.

Further preferred configurations of the invention result themselves 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;

Fig. 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 product 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 to 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 arrives, 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 transmits.

A non-driven pressure roller 23 is with its axis arranged at one end of a further lever 24. The in about a lever 24 extending 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 feeder 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 device.

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 in 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 there is the tensioning wheel 26 in this second end position approximately at the middle of the Straight line. The second drive wheel 17 is located in relation 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. This reduces 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 tensioning 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 controlled.

To create 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, whereby it rotates 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 frictional connection 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 tape 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 that 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 belt and separated from the fed belt 2.

After the tape is clamped in the capping unit, the control system again transfers the tensioning wheel 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)

Belt pushing device of a strapping device for applying a belt around a packaged product, which is provided with an enveloping drive which has only one enveloping member which is guided with an inner surface over at least two wheels, at least one of the two wheels is designed as a drive wheel which can be brought into operative connection with a drive motor, as a result of which the enveloping member can be driven, the band can be pressed against an outer surface of the enveloping member by a pressure roller in order to generate a frictional force between the band and the enveloping member, by means of which the band can be pushed in one direction, the pressure roller is arranged in an area in which the enveloping member of one of the two wheels wraps around, whereby the cover member can be pressed against the one of the two wheels with the pressure roller, Means for reversing the direction of rotation of the enveloping member are provided, so that the belt can be moved in both a feed and a tensioning direction, and there is a further wheel opposite the outer surface (20) of the enveloping member, which is designed as a tensioning wheel (26), which presses the band (2) to apply a band tension to the enveloping member during a tensioning phase. Belt tensioning device according to claim 1, characterized in that the tensioning wheel (26) can be transferred into two end positions, the tensioning wheel (26) being arranged at a distance from the enveloping member in the first end position and the wrapping member partially wrapping around the tensioning wheel (26) in the second end position . Belt sliding device according to one or both of the preceding claims, characterized in that the tensioning wheel (26) is articulated on a lever (28). Belt sliding device according to one or more of the preceding claims, characterized by a second drive wheel (17) with which the latter can be driven by abutment against the outer surface (20) of the enveloping member. Belt sliding device according to claim 4, characterized in that the position of the second drive wheel (17) can be changed relative to the position of the first drive wheel (16). Belt sliding device according to claim 5, characterized in that the second drive wheel (17) is pivotably articulated on a lever (19), and that the second drive wheel (17) can be pressed against the enveloping member in particular with an elastic spring acting on the lever (19) . Belt sliding device according to one or more of the preceding claims 4 to 6, characterized in that only the second drive wheel (17) drives the enveloping member during a feed phase in which the belt is fed by pulling off a supply roll. Belt sliding device according to one or more of the preceding claims, characterized in that during a tensioning phase, in which the belt is pulled back to apply the belt tension against the feed direction, the enveloping member can only be driven by the first drive wheel (16). Belt sliding device according to one or more of the preceding claims 4 to 8, characterized in that the pressure roller (23) is provided with a sensor with which the rotational state, in particular a standstill, of the pressure roller (23) can be detected, with the sensor being used for a certain rotational state, in particular when the pressure roller is at a signal can be sent to a controller, whereby the controller switches off a drive motor of one of the drive wheels (16, 17), the controller then pressing the tensioning wheel (26) on the cover member and Generates a drive movement of the other drive wheel (16, 17). Belt pushing device according to one or more of the preceding claims, characterized in that the pressure roller (23) is arranged in the region of a wrap angle with which the enveloping member wraps around the deflection wheel (15), and that the pressure roller (23) there is the tape against the enveloping member and thereby presses the envelope member against the deflection wheel (15). Belt sliding device according to one or more of the preceding claims, characterized in that the enveloping member is a multiple V-belt (13). Belt sliding device according to one or more of the preceding claims, characterized in that a drive motor can be braked with countercurrent to avoid excessive belt feed. Belt sliding device according to one or more of the preceding claims, characterized in that the pressure roller (23) rests on the belt both in a feed, retraction and tensioning phase. Belt sliding device according to one or more of the preceding claims, characterized in that the tensioning wheel (26) engages with the enveloping member only during the tensioning phase. Strapping device for strapping a packaged item with a strap, in particular with a plastic strap, characterized by a strap sliding device (7) according to one or more of Claims 1 to 14.

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