EP3549876B1 - Strapping device with an electrical drive - Google Patents

Description

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 with 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, an oscillating friction shoe 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 replaceable accumulator for the energy supply, with which DC motors are supplied with electrical energy. The DC 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. A strapping device is for example in EP 1 413 519 A disclosed.

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 strapping device having the features of the independent claim. 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 a high level of 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. The belt retraction speeds can be adjusted, especially in the case of such brushless motors, due to the possibility of the speed of the motor shaft and the motor torque to be set independently of one another in certain areas, adapt to the requirements required for the two clamping 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 in the form of a lithium-ion accumulator, with which energy can be made available for driving a connection device in the form of 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, the aim is to use welding shoe frequencies of approx. 250 - 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 falls 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 Accumulators can provide the voltage values required for a high speed for a significantly longer period of time. This means that lithium-ion batteries, in comparison to other batteries of comparable size, can still enable friction-welded closures with the desired strength for significantly longer, ie with a significantly higher number of straps. 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 during 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 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 greater 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 used as a be designed 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 weld 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 engine, which determine the rotational positions of the rotating engine components and make them available to the engine controller. This information can also be used with advantage, in particular, to control the friction welding device.

Thus, 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 another advantageous An embodiment of the invention can provide that the motor cannot be turned off in one or more specific rotational positions or can only be turned 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 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 lever device supplements the drive train of the strapping device, which in one embodiment of the invention also has a brushless direct current motor and a planetary gearbox for an automated transfer of the welding device into its welding position, since all components are able to generate 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.

Fig. 1

eine perspektivische Darstellung einer erfindungsgemässen Umreifungs vorrichtung;

Fig. 2

das Umreifungsgerät aus Fig. 1 ohne Gehäuse;

Fig. 3

eine teilweise geschnittene Darstellung des Motors der Umreifungsvorrichtung aus Fig. 1 zusammen mit auf der Motorwelle angeordneten Komponenten;

Fig. 4

eine stark schematisierte Darstellung des Motors zusammen mit seiner elektronischen Schaltung zur Kommutierung;

Fig. 5

eine perspektivische Teildarstellung des Antriebsstrangs des Umreifungsgeräts aus Fig. 1;

Fig. 6

der Antriebsstrang aus Fig. 5 in einer Darstellung aus einer anderen Blickrichtung;

Fig. 7

eine Seitenansicht des Antriebsstrangs aus Fig. 5 mit der Schweißeinrichtung in einer Ruheposition;

Fig. 8

eine Seitenansicht des Antriebsstrangs aus Fig. 5 mit der Schweißeinrichtung in einer Position zwischen zwei Endpositionen;

Fig. 9

eine Seitenansicht des Antriebsstrangs aus Fig. 5 mit der Schweißeinrichtung in einer Schweissposition.

Fig. 10

eine Seitenansicht auf die Spanneinrichtung des Umreifungsgerätes ohne Gehäuse, in der sich eine Spannwippe in einer Ruhestellung befindet;

Fig. 11

eine Seitenansicht auf die Spanneinrichtung des Umreifungsgerätes ohne Gehäuse, in der sich eine Spannwippe in einer Spannstellung befindet;

Fig. 12

die teilweise geschnitten dargestellte Spannwippe des Umreifungsgerätes aus Fig. 10 in einer Seitenansicht;

Fig. 13

die Spannwippe aus Fig. 12 in einer Frontansicht;

Fig. 14

ein Detail aus Fig. 12 gemäss der Linie C - C.

The invention is explained in more detail with reference to exemplary embodiments shown purely schematically in the figures, which show:

Fig. 1

a perspective view of a strapping device according to the invention;

Fig. 2

the strapping tool off Fig. 1 without housing;

Fig. 3

a partially sectioned view of the motor of the strapping device Fig. 1 together with components arranged on the motor shaft;

Fig. 4

a highly schematic representation of the motor together with its electronic circuit for commutation;

Fig. 5

a perspective partial representation of the drive train of the strapping device Fig. 1 ;

Fig. 6

the drive train off Fig. 5 in a representation from a different viewing direction;

Fig. 7

a side view of the powertrain Fig. 5 with the welding device in a rest position;

Fig. 8

a side view of the powertrain Fig. 5 with the welding device in a position between two end positions;

Fig. 9

a side view of the powertrain Fig. 5 with the welding device in a welding position.

Fig. 10

a side view of the tensioning device of the strapping device without a housing, in which a tensioning rocker is in a rest position;

Fig. 11

a side view of the tensioning device of the strapping tool without a housing, in which a tensioning rocker is in a tensioning position;

Fig. 12

the tensioning rocker of the strapping device shown partially in section Fig. 10 in a side view;

Fig. 13

the rocker arm off Fig. 12 in a front view;

Fig. 14

a detail Fig. 12 according to line C - C.

That in the Fig. 1 and 2 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 detail) which is connected to the base plate.

With the strapping device 1 an in Fig. 1 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 cooperates 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, is applied to the Strapping band and a simultaneous oscillating movement with 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 ( Fig. 6 ) 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 Fig. 1 and 2 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 activities of an operator 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, which can be preset in stages, is reached or tensile stress in the band 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 material to be strapped under the strap. 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 Fig. 3 A transmission device 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 as the drive movement of the welding device 10.

The in Fig. 4 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 control 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 can thus (Phase 1, Phase 2, Phase 3) can be switched depending on the position of the rotor 20 in order to cause a rotary movement of the rotor in a certain 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 controls it. 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. There can be direction of rotation, speed of rotation, current limitation 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 embodiment has eight cells and has 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 arranged on the motor-side drive shaft, 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 planetary 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 gear 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 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 around 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, each arranged on a shaft 30 running parallel to the motor shaft 27. The shafts 30 of the three gears 31 are stationary, ie they do not rotate around the motor shaft 27. The three gears 31 are again in engagement 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, i.e. a 60-fold reduction takes place due to the two-stage planetary gear.

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 ( Fig. 2 ). 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. About a Sun gear 47 as well as three planet gears 48 are thereby set in rotation the tensioning gear 49 of the tensioning device 6, which is designed as an internally toothed ring gear. The tensioning wheel 7, which is provided with a surface structure on its outer surface, entrains the respective strapping band during its rotational movement by means of a frictional connection, whereby the intended band tension is applied to the band loop.

The output gear 40 is designed in the area of its outer circumferential surface as a gear on which a toothed belt 50 of a casing drive is arranged ( FIGS. 5 and 6 ). The toothed belt 50 also loops around a pinion 51 with a smaller diameter than the output gear 40, the shaft of which 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 axis of rotation 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 previously known manner.

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 ( Fig. 7 ) into a welding position ( Fig. 9 ) 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 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 Figures 7 to 9 - The cam wheel 33 under the pivot element 63 arrives ( Fig. 8 ). A surface 32a of the cam 32 that rises like a ramp 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 arranged 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 Figures 7 and 9 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 Figures 7 to 9 - rotated clockwise. Here, the toggle lever 61 is taken along by the pivot element 63. In Fig. 8 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 Fig. 9 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 pivot element 63 against a stop (not shown in detail) and the welding shoe 53 against the two layers of tape 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 Fig. 6 and 9 Counterclockwise drive movement of the electric motor is transmitted from the toothed belt 50 to the welding shoe 53, which is now transferred 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 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 ( Fig. 7 ) 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 Fig. 8 illustrated - cuts. Since such a position is avoided, the rocker ( Fig. 2 ) released from the tensioning wheel 7 and, in addition, the toggle lever 61 in the direction of the cam wheel 33 into the in Fig. 7 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 adjusted on the strapping device preferably by means of a push button in nine stages, the nine different Belt tension values can be adjusted. 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 Fig. 2 , 10 , 11 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 Fig. 2 unrecognizable, rotatable cam disk moves. Via the rocker lever 9, the cam disk can perform a rotary movement of approx. 30 ° and move the rocker 8 or clamping plate 12 relative to the tensioning wheel 7, which enables the strap to be inserted into the strapping device or between the tensioning wheel 7 and clamping 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 Fig, 10 shown rest position in an off Fig. 11 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 Fig. 11 shown, during a strapping process, the two-ply tape is located between the tensioning plate and the tensioning wheel and therefore 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 Fig. 10 and 11 as well as in the detailed representations of the Figures 12-14 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 Fig. 11 and 12th results, the convex curvature runs in a direction parallel to the direction of the tape run 70, while the contact surface 12b is flat transversely to this direction ( Fig. 13 ). 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. In addition to being tiltable, the clamping plate 12 is also arranged on the rocker 8 so that it can be moved longitudinally.

During a clamping process, the clamping rocker 8 is first moved from the rest position ( Fig. 10 ) in the clamping position ( Fig. 11 ) 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 clamping 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 is directed towards the belt by a longitudinal movement in the recess during the pressing process 71 as well as a tilting movement over the contact surface 12b on the support surface 72 automatically so that the tensioning plate 12 exerts pressure on the strapping that is as uniform as possible over its entire length. 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. <b> List of reference symbols </b> 1 Strapping tool 1 30th wave 2 casing 31 gear 3 Handle 32 cam 4th Base plate 32a area 6th Clamping device 33 Cam wheel 7th Tensioning wheel 35 Sun gear 7a Circumferential surface 36 Freewheel 8th Seesaw 37 Planetary gear 8a Rocker pivot axis 38 Ring gear 9 Rocker arm 39 wave 10 Friction welding device 40 Output gear 11 Welding shoe 42 Freewheel 12th Clamping plate 43 Bevel gear 12a Clamping surface 46 Planetary gear 12b Contact area 47 Sun gear 13th Transmission device 48 Planetary gear 14th electric DC motor 49 Tensioning wheel 15th accumulator 50 Timing belt 16 Actuator 51 pinion 17th counter 52 Eccentric drive 18th Actuator 53 Welding shoe 19th Transfer facility 54 Eccentric shaft 20th rotor 55 eccentric HS1 Hall sensor 56 Welding shoe arm HS2 Hall sensor 57 Rotation axis eccentric shaft HS3 Hall sensor 60 Toggle mechanism 22nd electronic control 61 longer knee lever 24 stator 62 Swivel axis 25th Bridge circuit 63 Swivel element 27 motor-side output shaft 64 Contact element 28 Sun gear 65 Swivel axis 66 Swivel axis 72 Support surface 67 Compression spring 73 screw 68 Connecting line 74 Long hole 69 Swivel axis 70 Direction of tape run 71 Recess

Claims (8)

1. Mobile and portable strapping device for strapping packing goods with a strapping tape, said device having
   a tensioning installation (6) for applying a tape tension to a loop of a strapping tape; as well as
   a connection installation which for generating a connection on two regions of the loop of the strapping tape that lie on top of one another is configured as a friction-welding installation (10); and
   a rechargeable energy accumulator for storing energy which as driving energy for motorized driving movements is releasable at least to the connection installation and to the tensioning installation, characterized by
   a brushless DC motor (14) as a common drive for the tensioning installation (6) and the friction-welding installation (10),
   wherein the mobile strapping device has an activation element (16) which is configured as a pressure switch and for which three modes can be set by means of a switch (17),
   wherein in a first mode, by activating the activation element (16) without any further activities by a user being necessary, the tensioning installation (6) as well as the friction-welding installation (10) are triggered successively and in an automated manner, wherein for setting a second mode the switch (17) is switched to a second switching mode, and
   wherein in the second possible mode, by activating the activation element (16), only the tensioning installation (6) is then triggered, and for separately triggering the friction-welding installation (10) either a second activation element (18) has to be activated by the user, or it is provided that the first activation element (16) for triggering the friction-welding installation is to be activated a second time, and wherein the third mode is a type of semi-automatic mode in which the tensioning button (16) is to be pushed until the tension force in the strap that is able to be pre-set in stages or in a stepless manner is reached, wherein it is possible in this mode to interrupt the tensioning procedure by releasing the tensioning button (16) and for the tensioning procedure to be continued by pushing the tensioning button.
2. Mobile and portable strapping device according to Claim 1, characterized in that the third mode is able to be combined with a friction-welding procedure which is to be separately triggered as well as with an automatically following friction-welding procedure.
3. Mobile and portable strapping device according to at least one of the preceding claims, characterized by means for automatically switching off the electric drive.
4. Mobile and portable strapping device according to at least one of the preceding claims, characterized by means for determining the rotary position of the motor shaft, or a position of an element which is disposed in the drivetrain of the welding installation so as to depend on the position of the motor shaft.
5. Mobile and portable strapping device according to Claim 2, characterized by at least one detector, preferably a plurality of detectors, in particular at least three detectors, which for determining the rotary position of the motor shaft is/are disposed on the electric drive.
6. Mobile and portable strapping device according to Claim 1 or 2, characterized by detectors for determining the rotary position of the motor shaft, said detectors moreover being a component part of a circuitry for controlling an electronically generated commutation of the electric drive.
7. Mobile and portable strapping device according to at least one of the preceding claims, characterized in that a duration of a welding cycle during which the friction-welding installation is in use is able to be set, wherein the duration is able to be pre-determined as a function of a number of revolutions of the electric drive.
8. Mobile and portable strapping device according to at least one of the preceding claims, characterized by a tensioning cycle of the tensioning installation that is controlled by a rotating speed, the electric drive during said tensioning cycle being at least temporarily operated at different rotating speeds at a torque which is at least substantially constant.

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