Strapping device with electrical drive

The invention relates to a mobile strapping device for strapping packaged goods with a strapping tape, which has a tensioning device for applying tape tension to a loop of a strapping tape, as well as a connecting device for creating a connection at two superimposed areas of the loop of the strapping tape, and a rechargeable energy store for storage of energy, which can be released as drive energy for motorized drive movements at least for the connecting device and / or for the clamping device.

Such mobile strapping devices are used for strapping packaged goods with a plastic strap. For this purpose, a loop of the respective plastic strap is placed around the packaged goods. As a rule, the plastic tape is pulled off a supply roll. After the loop has been completely placed around the packaged goods, the end area of ​​the tape overlaps a section of the tape loop. The strapping device is now applied to this two-layer area of ​​the strap, the strap is clamped in the strapping device, strap tension is applied to the strap loop by means of the tensioning device and a closure is created on the loop between the two strap layers by means of the connecting device. Various locking technologies are possible here, including friction welding, among others. In the case of the latter, a friction shoe moving in an oscillating manner is used to press the belt in the area of ​​two ends of the belt loop. The pressure and the heat generated by the movement locally melts the band, which is usually made of plastic, for a short time. This creates a permanent connection between the two layers of tape that can at most be released again with great force. The loop is then separated from the supply roll. The respective packaged goods are strapped as a result.

Strapping devices of this type generally have a rechargeable and optionally exchangeable accumulator for the energy supply, with which direct current motors are supplied with electrical energy. The direct current motors are provided in the portable mobile strapping devices for generating drive movements of the tensioning device and / or the welding device.

Such mobile strapping devices of the generic type are often used continuously in industry for packaging goods. The aim is therefore to operate the strapping devices as simply as possible. This is intended to ensure, on the one hand, high functional reliability of the strapping device combined with the production of high-quality strapping and, on the other hand, the lowest possible stress for the operating people. Previously known strapping devices are not completely satisfactory in this regard.

The invention is therefore based on the object of creating a generic mobile strapping device of the type mentioned at the outset which, despite the possibility of at least largely automated generation of strap strapping, has a high level of functional reliability and good handling properties.

In a strapping device of the type mentioned at the outset, this object is achieved according to the invention by a brushless direct current motor as a drive for the tensioning device and / or connecting device. As will be explained in more detail below, brushless DC motors have electrical and mechanical properties that result in particular advantages in connection with mobile strapping tools. In addition, such motors are largely free of wear and tear and maintenance, which contributes to the high functional reliability of the strapping tools.

Furthermore, a speed-dependent or speed-controlled tensioning process, as is now possible with brushless DC motors, also enables a quick first tensioning, i.e. tensioning with a high belt retraction speed, which is followed by a second tensioning process with a lower belt retraction speed compared to the first tensioning process. With such brushless motors in particular, the belt retraction speeds can be adjusted independently of one another in certain ranges, due to the possibility of setting the speed of the motor shaft and the motor torque to the requirements required for the two tensioning processes. With the described division into a first and at least one second tensioning process, particularly high belt tensions can be achieved.

A strapping device according to the invention can furthermore have an energy store designed as a lithium-ion accumulator, with which energy can be made available to drive a connecting device designed as a friction welding device. It has been shown that particularly good functional reliability can also be achieved with such accumulators, since these accumulators provide sufficient energy to carry out a high number of strapping cycles with mobile strapping devices, even when high strap tension is applied and strapping processes that are at least largely automated motor drive movements are to take place.

It has also been shown that lithium-ion accumulators in combination with friction welding devices can be seen as an ideal addition to other storage devices for electrical energy. The friction welding process as such is dependent on the pressure of the two bands on one another and on the frequency of the welding shoe or welding element moving in an oscillating manner. To weld PP or PET tapes, welding shoe frequencies of approx. 250 - Aimed for 300 Hz with a contact pressure of 300 - 350 N. In order to achieve these values, a speed of rotation of an eccentric driving the welding shoe of approx. 6000 rpm to 7000 rpm is required on the drive side. Ideally, with these initial values, a welding process takes place in a period of 1.5 seconds to 2 seconds. If the speed of the eccentric shaft drops below 6000 rpm, the quality of the strap closure deteriorates significantly.

It has now been shown within the scope of the invention that the early decreasing quality of the closures observed with conventional hand strapping tools, although the batteries are not even 60% discharged, does not show up in this way with lithium-ion batteries. Lithium-ion batteries can provide the voltage values ​​required for a high speed for a significantly longer period of time. In comparison to other batteries of comparable size, lithium-ion accumulators can thus enable significantly longer, ie with a significantly higher number of strapping, still friction-weld closures with the desired strength. Only shortly before the stored energy is completely consumed does the supply voltage provided by lithium-ion batteries drop to values ​​that should be avoided in friction welding processes. After roughly the point in time at which the user should be prompted by a corresponding signal from the strapping device to charge the battery due to an imminent complete discharge of the lithium-ion battery, coincides with the point in time from which the battery is also not of good quality Allows more friction locks, in contrast to conventional accumulators, the signal for charging can also be provided as an indication for the user, that from now on the required quality of the strapping still produced is no longer given.

Since lithium-ion batteries have a significantly higher energy density than conventional batteries, these advantages can even be achieved with batteries that are smaller in terms of size. The lower weight of the accumulators used, which is thus possible, is a further significant advantage, particularly for use in mobile, portable strapping devices.

Particular advantages can be achieved by using lithium-ion batteries in conjunction with at least one brushless direct current motor as a drive for the clamping device and / or friction welding device. This can be further increased by a planetary gear, in particular if the at least one planetary gear is arranged together with the brushless DC motor and the lithium-ion battery in the drive train for the tensioning device and / or friction welding device.

An embodiment of the strapping device in which the tensioning device and the welding device are provided with only one common drive can also have independent significance. This only one drive can preferably be designed as an electric motor, with the drive movement of which the clamping device and the friction welding device can be driven one after the other. Preferably, with this only one motor, not only the drive movement of the welding process itself, but also a movement of the friction welding device from a rest position to a welding position in which a welding element of the friction welding device rests with pressure on the strip layers to be welded together and is applied by an oscillating movement a friction-welded connection is created between the layers of the tape. In this case, the welding element of the friction welding device is preferably inactive in the rest position and is preferably only started when a movement out of the rest position begins.

According to a further aspect of the present invention, which can also have an independent meaning, the strapping device is provided with means by which rotational positions of the motor shaft or positions of components of the strapping device that are dependent on the motor shaft can be determined. The information about one or more rotational positions can preferably be used by a control of the strapping device to control components of the strapping device, such as the friction welding device and / or the tensioning device. If a brushless direct current motor is used as the drive, this can be done in a particularly simple manner. For their commutation, such motors have to determine information about the instantaneous positions of the rotating component of the motor, which is usually designed as a rotating armature. For this purpose, detectors or sensors, such as Hall sensors, are provided on the motor, which determine the rotational positions of the rotating motor components and make them available to the motor controller. This information can also be used to advantage, in particular, to control the friction welding device.

In a preferred embodiment of the strapping device, it can be provided that a number of revolutions of the rotating component of the motor is determined in order to carry out a switching process when a predetermined value for the revolutions is reached. This switching process can, in particular, involve switching off the friction welding device in order to terminate the creation of a friction welding connection. In a further advantageous embodiment of the invention, it can be provided that the motor cannot be switched off in one or more specific rotational positions or can only be switched off in one or more specific rotational positions.

Finally, it has been shown to be advantageous if a toggle lever device is provided for transferring the welding device from the rest position to the welding position and back. The levers of the toggle lever device connected to one another via a joint can be brought into their two end positions by overcoming two dead center positions, in which they hold the welding device in the rest position or in the welding position. The toggle lever device is advantageously held at least in the two end positions by a force in each case, preferably by a force emitted by a mechanical spring. The toggle lever device should only be able to move from one end position to the other by overcoming this force. The toggle lever device has the advantage that the end positions of the welding device can only be changed by overcoming comparatively high torques. Since this applies in particular to the welding position, the toggle lever device contributes to a further increase in the functional reliability of the strapping device. Furthermore, the toggle device complements the drive train of the strapping device, which in one embodiment of the invention is not only the toggle device but also a brushless direct current motor and a planetary gear, for an automated transfer of the welding device into its welding position, since all components are able to generate and / or generate high torques only perform movements when applying high torques.

Further preferred embodiments of the invention emerge from the claims, the description and the drawing.

The invention is explained in more detail with reference to exemplary embodiments shown purely schematically in the figures, which show:<dl id="dl0001"><dt>Fig. 1</dt><dd>a perspective view of a strapping device according to the invention;</dd><dt>Fig. 2</dt><dd>the strapping tool off <figref idref="f0001">Fig. 1</figref> without housing;</dd><dt>Fig. 3</dt><dd>a partially sectioned view of the motor of the strapping device <figref idref="f0001">Fig. 1</figref> together with components arranged on the motor shaft;</dd><dt>Fig. 4</dt><dd>a highly schematic representation of the motor together with its electronic circuit for commutation;</dd><dt>Fig. 5</dt><dd>a perspective partial representation of the drive train of the strapping device <figref idref="f0001">Fig. 1</figref>;</dd><dt>Fig. 6</dt><dd>the drive train off <figref idref="f0005">Fig. 5</figref> in a representation from a different viewing direction;</dd><dt>Fig. 7</dt><dd>a side view of the powertrain <figref idref="f0005">Fig. 5</figref> with the welding device in a rest position;</dd><dt>Fig. 8</dt><dd>a side view of the powertrain <figref idref="f0005">Fig. 5</figref> with the welding device in a position between two end positions;</dd><dt>Fig. 9</dt><dd>a side view of the powertrain <figref idref="f0005">Fig. 5</figref> with the welding device in a welding position.</dd><dt>Fig. 10</dt><dd>a side view of the tensioning device of the strapping device without a housing, in which a tensioning rocker is in a rest position;</dd><dt>Fig. 11</dt><dd>a side view of the tensioning device of the strapping tool without a housing, in which a tensioning rocker is in a tensioning position;</dd><dt>Fig. 12</dt><dd>the partially sectioned rocker of the strapping tool <figref idref="f0007">Fig. 10</figref> in a side view;</dd><dt>Fig. 13</dt><dd>the rocker arm off <figref idref="f0009">Fig. 12</figref> in a front view;</dd><dt>Fig. 14</dt><dd>a detail <figref idref="f0009">Fig. 12</figref> according to the line C - C.</dd></dl>

That in the <figref idref="f0001">Fig. 1</figref> and <figref idref="f0002">2</figref> The exclusively hand-operated strapping device 1 according to the invention shown has a housing 2 which surrounds the mechanism of the strapping device and on which a handle 3 for handling the device is formed. The strapping device is also provided with a base plate 4, the underside of which is provided for arrangement on an object to be packaged. All functional units of the strapping device 1 are fastened on the base plate 4 and on the carrier of the strapping device (not shown in greater detail) connected to the base plate.

With the strapping device 1 an in <figref idref="f0001">Fig. 1</figref> Loop (not shown) of a plastic tape, for example made of polypropylene (PP) or polyester (PET)), which was previously placed around the object to be packaged, can be tensioned by means of a tensioning device 6 of the strapping device. For this purpose, the tensioning device has a tensioning wheel 7 with which the band can be gripped for a tensioning process. The tensioning wheel 7 interacts with a rocker 8, which can be pivoted by means of a rocker lever 9 from an end position at a distance from the tensioning wheel to a second end position around a rocker pivot axis 8a, in which the rocker 8 is pressed against the tensioning wheel 7. The band located between the tensioning wheel 7 and the rocker 8 is also pressed against the tensioning wheel 7. By rotating the tensioning wheel 7, it is then possible to provide the tape loop with a tape tension that is sufficiently high for the packaging purpose. The tensioning process and the rocker 8, which is advantageously designed for this purpose, will be explained in more detail below.

The two layers can then be welded by means of the friction welding device 8 of the strapping device at a point on the tape loop at which two layers of the tape lie one above the other. This allows the tape loop to be closed permanently. For this purpose, the friction welding device 10 is provided with a welding shoe 11 which, by mechanical pressure on the strapping band and a simultaneous oscillating movement at a predetermined frequency, melts the two layers of the strapping band. The plasticized or melted areas flow into one another and after the tape has cooled down, a connection is created between the two tape layers. If necessary, the band loop can then be separated from a supply roll of the band by means of a cutting device, not shown in detail, of the strapping device 1.

The actuation of the clamping device 6, the infeed of the friction welding device 10 by means of a transfer device 19 (<figref idref="f0005">Fig. 6</figref>) the friction welding device 10 as well as the use of the friction welding device per se and the actuation of the cutting device take place using only one common electric motor 14, which provides a drive movement for each of these components. For its power supply, an exchangeable and, in particular, removable accumulator 15 is arranged on the strapping tool. A supply of other external auxiliary energy, such as compressed air or other electricity, is possible with the strapping device according to FIGS <figref idref="f0001">Fig. 1</figref> and <figref idref="f0002">2</figref> not provided.

In the present case, the portable mobile strapping device 1 has an actuating element 16 designed as a pressure switch, which is provided for starting up the motor. Three modes can be set for the actuating element 16 by means of a switch 17. In the first mode, both the clamping device 6 and the friction welding device 10 are triggered in succession and in an automated manner by actuating the actuating element 16, without further operator activity being required. To set the second mode, the switch 17 is switched to a second switching mode. In the second possible mode, only the tensioning device 6 is triggered by actuating the actuating element 16. To trigger the friction welding device 10 separately, a second actuating element 18 must be actuated by the operator. In alternative embodiments, it can also be provided that, in this mode, the first actuating element 16 is to be actuated a second time in order to trigger the friction welding device. The third mode is a kind of semi-automatic mode, in which the tensioning button 16 must be pressed until the tensioning force or tension in the belt, which can be preset in stages, is reached. In this mode, it is possible to interrupt the tensioning process by releasing the tensioning button 16, for example to attach edge protectors to the strapping material under the strapping band. The tensioning process can then be continued again by pressing the tensioning button. This third mode can be combined both with a separately triggered and with an automatically subsequent friction welding process.

On an in <figref idref="f0003">Fig. 3</figref> A gear mechanism 13 is arranged on the motor shaft 27 of the motor, which is designed as a brushless, grooved internal rotor direct current motor 14, as shown. In the exemplary embodiment shown here, a motor from Maxon Motor AG, Brünigstrasse 20, 6072 Sachseln, of the type ECI40 is used. The brushless direct current motor 14 can be operated in both directions of rotation, one direction of rotation being used as the drive movement of the clamping device 6 and the other direction of rotation being used as the drive movement of the welding device 10.

The in <figref idref="f0004">Fig. 4</figref> The brushless direct current motor 14 shown purely schematically is designed with a grooved internal rotor (rotor) 20 with three Hall sensors HS1, HS2, HS3. This EC motor (electronically commutated motor) has a permanent magnet in its rotor 20 and is provided with an electronic controller 22 which is provided in the stator 24 for electronic commutation. The electronic control 22 determines the current position of the rotor 20 via the Hall sensors HS1, HS2, HS3, which in the exemplary embodiment also assume the function of position sensors, and switches the electrical magnetic field in the windings of the stator 24. The phases (phase 1, phase 2, phase 3) can thus be switched depending on the position of the rotor 20 in order to effect a rotary movement of the rotor in a specific direction of rotation with a predeterminable variable speed and torque. In the present case, a so-called "1 quadrant motor drive amplifier" is used, which provides the motor with the voltage as well as peak and continuous current and regulates this. The current flow for coil strands, not shown in detail, of the stator 24 is regulated, ie commutated, via a bridge circuit 25 (MOSFET transistors). Furthermore, a temperature sensor (not shown) is provided on the engine. The direction of rotation, the speed of rotation, the current limit and the temperature can be monitored and controlled. The commutation is built up as a separate printed component and housed separately from the motor in the strapping device.

The power supply is ensured by the accumulator 15 designed as a lithium-ion accumulator. Batteries of this type are based on several independent lithium-ion cells in which chemical processes for generating a potential difference between two poles of the respective cell run at least essentially separately from one another. The exemplary embodiment is a lithium-ion battery from the manufacturer Robert Bosch GmbH, D-70745 Leinfelden-Echterdingen. The battery of the exemplary embodiment has eight cells and a capacity of 2.6 ampere hours. Graphite is provided as the active material or as the negative electrode of the lithium-ion battery. The positive electrode of the accumulator often has lithium metal oxides, in particular in the form of layered structures. Anhydrous salts such as lithium hexafluorophosphate or polymers are usually used as the electrolyte. The voltage delivered by a conventional lithium-ion battery is usually 3.6 volts. The energy density of such accumulators is around 100 Wh / kg - 120 Wh / kg.

The transmission device 13 has a freewheel 36 which is arranged on the drive shaft on the motor side and on which a sun gear 35 of a first planetary gear stage is arranged. The freewheel 36 transmits the rotary movement to the sun gear 35 only in one of the two possible directions of rotation of the drive. The sun gear 35 meshes with three planetary gears 37 which are in engagement with a stationary ring gear 38 in a manner known per se. Each of the planetary gears 37 is in turn arranged on a shaft 39 assigned to it, which is connected in one piece to an output gear 40. The rotation of the planet gears 37 around the motor shaft 27 results in a rotational movement of the output gear 40 around the motor shaft 27 and determines a rotational speed of this rotational movement of the output gear 40.In addition to the sun gear 35, the output gear 40 is also located on the freewheel 36 and is therefore also on the motor shaft stored. This freewheel 36 leads to the fact that both the sun gear 35 and the driven gear 40 rotate only in one direction of rotation of the rotational movement of the motor shaft 27. The freewheel 29 can be of the type INA HFL0615, for example, as offered by Schaeffler KG, D-91074 Herzogenaurach.

On the motor-side output shaft 27, the transmission device 13 also has a toothed sun gear 28 belonging to a second planetary gear stage, through the recess of which the shaft 27 is passed, but in this case the shaft 27 is not connected to the sun gear 28. The sun gear is attached to a disk 34, which in turn is connected to the planet gears 37. The rotational movement of the planetary gears 37 about the motor-side output shaft 27 is thus transmitted to the disk 34, which in turn transmits its rotational movement to the sun gear 28 at the same speed. The sun gear 28 meshes with several planet gears, namely three gearwheels 31 each arranged on a shaft 30 running parallel to the motor shaft 27. The shafts 30 of the three gearwheels 31 are stationary, ie they do not rotate around the motor shaft 27. The three gears 31 are in turn in mesh with an internally toothed ring gear which has a cam 32 on its outside and is referred to below as cam wheel 33. The sun gear 28, the three gears 31 and the cam gear 33 are components of the second planetary gear stage. The rotational movement of the shaft 27 on the input side of the planetary gear and the rotational movement of the cam wheel 33 are in a ratio of 60: 1, ie The two-stage planetary gear provides a 60-fold reduction.

At the end of the motor shaft 27, a bevel gear 43 is also arranged on a second freewheel 42, which is in engagement with a second bevel gear, not shown in detail. This freewheel 42 also transmits the rotary movement only in one direction of rotation of the motor shaft 27. The direction of rotation in which the freewheel 36 of the sun gear 35 and the freewheel 42 transmit the rotational movement of the motor shaft 27 are opposite to one another. This means that only the freewheel 36 rotates in one direction of rotation and only the freewheel 42 rotates in the other direction of rotation.

The second bevel gear is arranged at one end of a tensioning shaft, not shown, which carries a further planetary gear 46 at its other end (<figref idref="f0002">Fig. 2</figref>). The drive movement of the electric motor in a specific direction of rotation is thus transmitted to the two bevel gears 43 to the tensioning shaft. The tensioning wheel 49 of the tensioning device 6, which is designed as an internally toothed ring gear, is set in rotation via a sun gear 47 and three planetary gears 48. The tensioning wheel 7, which is provided with a surface structure on its outer surface, takes the respective strapping band along with it during its rotational movement by means of a frictional connection, as a result of which the intended band tension is applied to the band loop.

In the area of ​​its outer circumferential surface, the output gear 40 is designed as a gear on which a toothed belt 50 of a casing drive is arranged (<figref idref="f0005">FIGS. 5 and 6</figref>). The toothed belt 50 also loops around a pinion 51 which is smaller in diameter than the output gear 40 and whose shaft drives an eccentric drive 52 for an oscillating back and forth movement of the welding shoe 53. Instead of a toothed belt drive, any other form of envelope drive could also be provided, for example a V-belt or chain drive. The eccentric drive 52 has an eccentric shaft 54 ​​on which an eccentric 55 is arranged, on which in turn a welding shoe arm 56 with a circular recess is seated. The eccentric rotational movement of the eccentric 55 about the rotational axis 57 of the eccentric shaft 54 ​​leads to a translatory oscillating back and forth movement of the welding shoe 53. Both the eccentric drive 52 and the welding shoe 53 itself can also be designed in any other manner known per se.

The welding device is also provided with a toggle lever device 60, by means of which the welding device is moved from a rest position (<figref idref="f0006">Fig. 7</figref>) into a welding position (<figref idref="f0006">Fig. 9</figref>) can be transferred. The toggle lever device 60 is attached to the welding shoe arm 56 and is provided with a longer toggle lever 61 which is pivotably articulated on the welding shoe arm 56. The toggle lever device 60 is also provided with a pivoting element 63 which is articulated so as to be pivotable about a pivot axis 62 and which functions as a shorter toggle lever in the toggle lever device 60. The pivot axis 62 of the pivot element 63 runs parallel to the axes of the motor shaft 27 and the eccentric shaft 57.

The pivoting movement is set in motion by means of the cam 32 of the cam wheel 33, which in the counterclockwise direction - based on the representations of the <figref idref="f0006">Figures 7 to 9</figref> - the cam wheel 33 comes under the swivel element 63 (<figref idref="f0006">Fig. 8</figref>). A ramp-like surface 32a of the cam 32 touches a contact element 64 inserted into the pivot element 63. The pivot element 63 is thereby rotated clockwise about its pivot axis 62. In the area of ​​a concave recess of the pivot element 63, a two-part longitudinally variable toggle lever rod of the toggle lever 61, which is based on the "piston-cylinder" principle, is pivotable about a pivot axis 69. The latter is also rotatably articulated to an articulation point 65, designed as a further pivot axis 65, of the welding shoe arm 56 in the vicinity of the welding shoe 53 and at a distance from the pivot axis 57 of the welding shoe arm 56. Between the two ends of the longitudinally variable toggle lever rod there is a compression spring 67, by means of which the toggle lever 61 is pressed both against the welding shoe arm 56 and against the swivel element 63. The pivoting element 63 is thus operatively connected to the toggle lever 61 and the welding shoe arm 56 with regard to its pivoting movements.

As in the representations of the <figref idref="f0006">Figures 7 and 9</figref> As can be seen, in the rest position there is an (imaginary) connecting line 68 running through the toggle lever 61 of the two articulation points of the toggle lever 61 between the pivot axis 62 of the pivot element 63 and the cam wheel 33, i.e. on one side of the pivot axis 62 Cam wheel 33 is the pivot element 63 - in relation to the illustrations of <figref idref="f0006">Figures 7 to 9</figref> - rotated clockwise. Here, the toggle lever 61 is taken along by the pivot element 63. In<figref idref="f0006">Fig. 8</figref> an intermediate position of the toggle lever 61 is shown, in which the connecting line 68 of the articulation points 65, 69 intersects the pivot axis 62 of the pivot element 63. In the in<figref idref="f0006">Fig. 9</figref> The end position of the movement shown (welding position) is the toggle lever 61 with its connecting line 68 in relation to the cam wheel 33 and the rest position on the other side of the pivot axis 62 of the pivoting element 63 Rest position transferred into the welding position by rotation about the pivot axis 57. In the latter, the compression spring 67 presses the swivel element 63 against a stop (not shown in detail) and the welding shoe 53 against the two strip layers to be welded together. The toggle lever 61 and thus also the welding shoe arm 56 are thus in a stable welding position.

The ones in the representation of <figref idref="f0005">Fig. 6</figref> and <figref idref="f0006">9</figref> Counterclockwise drive movement of the electric motor is transmitted from the toothed belt 50 to the welding shoe 53, which is now moved into the welding position by the toggle lever device 60, which presses on the two layers of tape and moves back and forth in an oscillating movement. The welding time for producing a friction weld connection is determined by the fact that the adjustable number of revolutions of the cam wheel 33 is counted from the point in time from which the cam 32 actuates the contact element 64. For this purpose, the number of revolutions of the shaft 27 of the brushless direct current motor 14 is counted in order to determine the position of the cam wheel 33 from which the motor 14 is to be switched off and the welding process is to be ended. The aim here is to prevent the cam 32 from remaining under the contact element 64 when the motor 14 is switched off. To switch off the motor 14, only relative positions of the cam 32 with respect to the pivot element 63 are provided, in which the cam 32 is not located below the pivot element. This ensures that the welding shoe arm 56 from the welding position back to the rest position (<figref idref="f0006">Fig. 7</figref>) can pivot. This in particular avoids a position of the cam 32 in which the cam 32 would arrange the toggle lever 61 in a dead center position, ie in a position in which the connecting line 68 of the two articulation points the pivot axis 62 of the pivot element 63 - as in FIG<figref idref="f0006">Fig. 8</figref> illustrated - cuts. Since such a position is avoided, the rocker (<figref idref="f0002">Fig. 2</figref>) released from the tensioning wheel 7 and, in addition, the toggle lever 61 in the direction of the cam wheel 33 in the in <figref idref="f0006">Fig. 7</figref> position shown can be swiveled. After the band loop has been removed from the strapping device, the latter is ready for another strapping process.

The described "clamping" and "welding" processes, which take place one after the other, can be triggered jointly in a switching state of the actuating element 16. For this purpose, the actuating element 16 is to be actuated once, whereby the electric motor 14 first runs in the first direction of rotation and in this case (exclusively) the clamping device 6 is driven. The strap tension to be applied to the respective strap can be set on the strapping device, preferably by means of a push button, in nine stages, which correspond to nine different strap tension values. As an alternative to this, a stepless adjustment of the belt tension could also be provided. Since the motor current depends on the torque of the tensioning wheel 7 and this in turn depends on the current strap tension, the strap tension to be applied can be set in the form of a limit value of the motor current via push buttons in nine stages on the control electronics of the strapping device.

After an adjustable and thus predeterminable limit value for the motor current or for the belt tension has been reached, the motor 14 is switched off by its controller 22. Immediately thereafter, the motor is operated by the controller 22 in the opposite direction of rotation. As a result, in the manner described above, the welding shoe 53 is lowered onto the two layers of tape lying one above the other and the oscillating movement of the welding shoe is carried out to produce the friction-welded connection.

By actuating the switch 17, the actuating element 16 can only be assigned the function of triggering the clamping device. If such a setting has been made, only the tensioning device is put into operation by actuating the actuating element and switched off again after the pre-set belt tension has been reached. In order to trigger the friction welding process, the second actuating element 18 must be actuated. Except for the separate triggering, however, the function of the friction welding device is identical to the other mode of the first actuating element.

As already explained above, the rocker 8 can by actuating the in the <figref idref="f0002">Fig. 2</figref>, <figref idref="f0007">10</figref>, <figref idref="f0008">11</figref> shown rocker lever 9 perform pivoting movements about the rocker axis 8a. The rocker is for this purpose by means of a behind the tensioning wheel 7 and therefore in<figref idref="f0002">Fig. 2</figref> unrecognizable, rotatable cam disk moves. The cam disk can rotate about 30 ° via rocker lever 9 and move rocker 8 or tensioning plate 12 relative to tensioning wheel 7, which enables the strap to be inserted into the strapping device or between tensioning wheel 7 and tensioning plate 12.

As a result, the toothed clamping plate 12 arranged in the region of the free end of the rocker on the latter can also be replaced by an in <figref idref="f0007">Fig, 10</figref> shown rest position in an off <figref idref="f0008">Fig. 11</figref> emerging clamping position and swiveled back again. In the rest position, the tensioning plate 12 has a sufficiently large distance from the tensioning wheel 7 so that a strapping band can be arranged in two layers between the tensioning wheel and the tensioning plate, as is necessary for the formation of a fastener on a tape loop. In the tensioned position, the tensioning plate 12 is pressed against the tensioning wheel 7 in a manner known per se, for example by means of a spring force acting on the rocker, wherein, unlike in FIG <figref idref="f0008">Fig. 11</figref> shown, during a strapping process, the two-ply tape is located between the tensioning plate and the tensioning wheel and thus no contact should take place between the latter two. The toothed surface 12a (clamping surface) facing the tensioning wheel 7 is concavely curved, the radius of curvature corresponding to the radius of the tensioning wheel 7 or being slightly larger.

As in particular in the <figref idref="f0007">Fig. 10</figref> and <figref idref="f0008">11</figref> as well as in the detailed representations of the <figref idref="f0009">Figures 12-14</figref> can be seen, the toothed clamping plate 12 is arranged in a groove-shaped recess 71 of the rocker. The length - in relation to the direction of the tape path - of the recess 71 is greater than the length of the tensioning plate 12. In addition, the tensioning plate 12 is provided with a convexly curved contact surface 12b with which it is supported in the recess 71 of the rocker 8 on a flat support surface 72 is. As can be seen in particular from the<figref idref="f0008">Fig. 11</figref> and <figref idref="f0009">12</figref> results, the convex curvature runs in a direction parallel to the direction of belt extension 70, while the contact surface 12b is flat transverse to this direction (<figref idref="f0009">Fig. 13</figref>). Due to this configuration, the tensioning plate 12 is able to perform tilting movements in the direction 70 of the tape run relative to the rocker 8 and to the tensioning wheel 7. Furthermore, the clamping plate 12 is fastened to the rocker 8 with a screw 73 passed through the rocker from below. For this purpose, the screw is located in an elongated hole 74 of the rocker, the longitudinal extent of which runs parallel to the course of the strap 70 in the strapping device. As a result, the clamping plate 12 is also arranged on the rocker 8 in a longitudinally displaceable manner in addition to being tiltable.

During a clamping process, the clamping rocker 8 is first moved from the rest position (<figref idref="f0007">Fig. 10</figref>) in the clamping position (<figref idref="f0008">Fig. 11</figref>) transferred. In the tensioned position, the spring-loaded rocker 8 presses the tensioning plate 12 in the direction of the tensioning wheel and thereby clamps both layers of tape between the tensioning wheel 7 and the tensioning plate 12. Due to different belt thicknesses, different distances between the tensioning plate 12 and the circumferential surface 7a of the tensioning wheel 7 can result. This not only results in different pivoting positions of the rocker 8, but also different positions of the tensioning plate 12 in relation to the circumferential direction of the tensioning wheel 7. In order to still achieve uniform contact pressure , the clamping plate 12 aligns itself during the pressing process against the belt by a longitudinal movement in the recess 71 and a tilting movement over the contact surface 12b on the support surface 72 so that the clamping plate 12 has as even pressure as possible over its entire length exerts on the strap. If the tensioning wheel 7 is now switched on, the toothing of the tensioning plate 12 holds the lower band layer in place, while the tensioning wheel 7 grips the upper band layer with its toothed circumferential surface 7a. The rotational movement of the tensioning wheel 7 and the lower coefficient of friction between the two tape layers then lead to the tensioning wheel pulling back the upper tape layer and thus increasing the tension in the tape loop up to the desired tensile stress value.

Other designs:

<ol id="ol0001" compact="compact"><li>1. Mobile strapping device for strapping packaged goods with a strapping tape, which has a tensioning device for applying tape tension to a loop of a strapping tape, as well as a connecting device for creating a connection on two superimposed areas of the loop of the strapping tape, and a rechargeable energy storage device for storing energy, as Drive energy for motorized drive movements can be released at least for the connecting device and / or for the clamping device, characterized by a brushless DC motor as a drive for the clamping device and / or connecting device.</li><li>2. Strapping device according to embodiment 1, characterized by a connecting device designed as a friction welding device.</li><li>3. Strapping device according to embodiment 1 or 2, characterized in that the energy store has a lithium-ion accumulator with which energy can be made available to drive a connecting device designed as a friction welding device.</li><li>4th Mobile strapping device according to at least one of the preceding embodiments, characterized by means for automatically switching off the electric drive.</li><li>5. Mobile strapping device according to at least one of the preceding embodiments, characterized by means for determining the rotational position of the motor shaft or the position of an element arranged in the drive train of the welding device as a function of the position of the motor shaft.</li><li>6th Mobile strapping device according to embodiment 5, characterized by at least one, preferably several, in particular at least three, detector arranged on the electric drive for determining the rotational position of the motor shaft.</li><li>7th Mobile strapping device according to embodiment 6, characterized by detectors for determining the rotational position of the motor shaft, which are also part of a circuit for controlling an electronically generated commutation of the electric drive.</li><li>8th. Mobile strapping device according to at least one of the preceding embodiments, characterized in that a duration of Welding cycle during which the friction welding device is in use can be set, the duration being predeterminable as a function of a number of revolutions of the electric drive.</li><li>9. Strapping device according to at least one of the preceding embodiments, characterized by a planetary gear for transmitting and changing the speed of a drive movement provided by an electric drive of the friction welding device.</li><li>10. Mobile strapping device according to at least one of the preceding embodiments, characterized in that the friction welding device is provided with a toggle lever device which can be pivoted between two end positions, one end position of the toggle lever device determining a friction welding position and the other end position determining a rest position in which the friction welding device is not in use is.</li><li>11. Mobile strapping device according to at least one of the preceding embodiments, characterized by a speed-controlled tensioning cycle of the tensioning device, during which the electric drive is operated at least temporarily at different speeds with at least essentially constant torque.</li><li>12th Method for strapping packaged goods with a strap by means of a mobile battery-operated strapping device, in which a loop of a strap is placed around packaged goods, then a tensioning device of the strapping device is used to apply strap tension to the loop, with a connecting device of the Strapping device a connection is created at two superimposed areas of the loop of the strapping tape, characterized in that, that by means of a brushless DC motor drive movements are provided for a speed-controlled first tensioning process and a subsequent second tensioning process, the second tensioning process being carried out at a reduced belt retraction speed compared to the first tensioning process. 13th Method according to embodiment 12, characterized in that the first and the second tensioning process are each carried out at substantially constant belt retraction speeds.</li></ol><tables id="tabl0001" num="0001"><table frame="none"><title><b>List of reference symbols</b></title><tgroup cols="4" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="13mm" /><colspec colnum="2" colname="col2" colwidth="48mm" /><colspec colnum="3" colname="col3" colwidth="13mm" /><colspec colnum="4" colname="col4" colwidth="48mm" /><tbody><row><entry>1</entry><entry>Strapping tool 1</entry><entry>32</entry><entry>cam</entry></row><row><entry>2</entry><entry>casing</entry><entry>32a</entry><entry>surface</entry></row><row><entry>3</entry><entry>Handle</entry><entry>33</entry><entry>Cam wheel</entry></row><row><entry>4</entry><entry>Base plate</entry><entry>35</entry><entry>Sun gear</entry></row><row><entry>6</entry><entry>Clamping device</entry><entry>36</entry><entry>Freewheel</entry></row><row><entry>7</entry><entry>Tensioning wheel</entry><entry>37</entry><entry>Planetary gear</entry></row><row><entry>7a</entry><entry>Circumferential surface</entry><entry>38</entry><entry>Ring gear</entry></row><row><entry>8</entry><entry>Seesaw</entry><entry>39</entry><entry>wave</entry></row><row><entry>8a</entry><entry>Rocker pivot axis</entry><entry>40</entry><entry>Output gear</entry></row><row><entry>9</entry><entry>Rocker arm</entry><entry>42</entry><entry>Freewheel</entry></row><row><entry>10</entry><entry>Friction welding device</entry><entry>43</entry><entry>Bevel gear</entry></row><row><entry>11</entry><entry>Welding shoe</entry><entry>46</entry><entry>Planetary gear</entry></row><row><entry>12</entry><entry>Clamping plate</entry><entry>47</entry><entry>Sun gear</entry></row><row><entry>12a</entry><entry>Clamping surface</entry><entry>48</entry><entry>Planetary gear</entry></row><row><entry>12b</entry><entry>Contact area</entry><entry>49</entry><entry>Tensioning wheel</entry></row><row><entry>13</entry><entry>Transmission device</entry><entry>50</entry><entry>Timing belt</entry></row><row><entry>14</entry><entry>electric DC motor</entry><entry>51</entry><entry>pinion</entry></row><row><entry>15</entry><entry>accumulator</entry><entry>52</entry><entry>Eccentric drive</entry></row><row><entry>16</entry><entry>Actuator</entry><entry>53</entry><entry>Welding shoe</entry></row><row><entry>17</entry><entry>counter</entry><entry>54</entry><entry>Eccentric shaft</entry></row><row><entry>18</entry><entry>Actuator</entry><entry>55</entry><entry>eccentric</entry></row><row><entry>19</entry><entry>Transfer facility</entry><entry>56</entry><entry>Welding shoe arm</entry></row><row><entry>20</entry><entry>rotor</entry><entry>57</entry><entry>Rotation axis eccentric shaft</entry></row><row><entry>HS1</entry><entry>Hall sensor</entry><entry>60</entry><entry>Toggle mechanism</entry></row><row><entry>HS2</entry><entry>Hall sensor</entry><entry>61</entry><entry>longer knee lever</entry></row><row><entry>HS3</entry><entry>Hall sensor</entry><entry>62</entry><entry>Swivel axis</entry></row><row><entry>22</entry><entry>electronic control</entry><entry>63</entry><entry>Swivel element</entry></row><row><entry>24</entry><entry>stator</entry><entry>64</entry><entry>Contact element</entry></row><row><entry>25</entry><entry>Bridge circuit</entry><entry>65</entry><entry>Swivel axis</entry></row><row><entry>27</entry><entry>motor-side output shaft</entry><entry>66</entry><entry>Swivel axis</entry></row><row><entry>28</entry><entry>Sun gear</entry><entry>67</entry><entry>Compression spring</entry></row><row><entry>30</entry><entry>wave</entry><entry>68</entry><entry>Connecting line</entry></row><row><entry>31</entry><entry>gear</entry><entry>69</entry><entry>Swivel axis</entry></row><row><entry>70</entry><entry>Direction of tape run</entry><entry>74</entry><entry>Long hole</entry></row><row><entry>71</entry><entry>Recess</entry><entry /><entry /></row><row><entry>72</entry><entry>Support surface</entry><entry /><entry /></row><row><entry>73</entry><entry>screw</entry><entry /><entry /></row></tbody></tgroup></table></tables>