Method for monitoring the function of a tubular bag machine

Abstract

A method for monitoring a tubular bag machine having a drive control system and independently controlled electronic drive units controlled by a drive control system for driving functional elements of the packing machine in a cycle time-synchronous manner in predefined motion sequences, one drive unit being a transverse sealing unit with a drive motor and two transverse sealing jaws for transversely sealing a film tube, and the drive motor torque measured using a drive controller, and the drive motor position measured using a position sensor, the method including moving the film tube into the sealing zone between the transverse sealing jaws, closing the jaws according to a predefined target torque stored in the drive control system, measuring the actual position of the drive motor upon reaching the target torque, and comparing the measured position to a target position stored in the drive control system associated with the predefined target torque.

Claims

1. A method for testing the function of a tubular bag machine, the tubular bag machine comprising a drive control system and multiple electronic drive units which are controlled independently of each other by the drive control system and which drive different functional elements of the tubular bag machine in a cycle time-synchronous manner as they are going through predefined motion sequences, and one drive unit being realized in the manner of a transverse sealing unit, and the transverse sealing unit comprising at least one drive motor (02) and two transverse sealing jaws (13a, 13b) which are driven relative to each other by the drive motor (02) and by means of which a film tube (09) is sealed transversely to a conveying direction (21), and a drive torque (M) of the drive motor (02) being measured directly or indirectly using a drive controller, and a position (φ) of the drive motor (02) being measured directly or indirectly using a position sensor, the method comprising the following steps: a) calibrating the transverse sealing unit by measuring a torque of the drive motor corresponding to a predefined target angular position of the drive motor stored in the drive control system, and storing said torque as a target torque in the drive control system; b) moving the film tube (09) into a sealing zone between the transverse sealing jaws (13a, 13b); c) closing the transverse sealing jaws (13a, 13b) according to the predefined target angular position stored in the drive control system; d) measuring an actual torque of the drive motor once the predefined target angular position has been reached; e) comparing the measured actual torque to the target torque stored in the drive control system and associated with the predefined target angular position.

2. The method according to claim 1, characterized in that step a) comprises measuring the torque of the drive motor corresponding to the predefined target angular position multiple times in a row, and further comprises calculating a mean torque value from said measuring step, the mean torque value being stored in the drive control system as the target torque associated with the predefined target angular position.

3. The method according to claim 1, characterized in that the actual torque is measured indirectly by the drive controller of the drive motor (02).

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) FIG. 1 shows a schematic side view of the transverse sealing unit of a known tubular bag machine;

(2) FIG. 2 shows a diagram relating to the determination of the target position associated with a target torque;

(3) FIG. 3 shows a diagram relating to the monitoring of the function of the transverse sealing unit of FIG. 1, taking into account a tolerance threshold.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 is a schematic of an example of the transverse sealing unit of a tubular bag machine comprising two transverse sealing jaws 13a and 13b which are moveable relative to each other.

(5) An endlessly produced film tube 09 which can be filled with material to be packaged by means of a filling tube 08 is visible in FIG. 1. Film tube 09 is transported in conveying direction 21. To produce the individual tubular bags, film tube 09 is sealed transversely. Transverse sealing jaws 13a and 13b are used to do so. Said transverse sealing jaws 13a and 13b can be moved toward each other and away from each other in transverse direction 22 transversely to conveying direction 21. In the sealing position, transverse sealing jaws 13a and 13b are moved against each other so that film tube 09 located between them can be compressed and sealed by heating transverse sealing jaws 13a and 13b. The technique for the transverse sealing of tubular bags is known in principle and requires no further explanation.

(6) In the exemplary embodiment illustrated in FIG. 1, transverse sealing jaws 13a and 13b are each disposed on support bars 16 which are mounted in a support bar mount 17 so as to be linearly displaceable in the transverse direction. Contrary movement of transverse sealing jaws 13a and 13b is realized by means of an eccentric mechanism. To this end, one eccentric element 14a and 14b per support bar 16 is mounted on drive shaft 04 so as to co-rotate therewith. In turn, a coupling element 15 which is connected to associated support bar 16 in a pivoting manner is mounted on each eccentric element 14a and 14b so as to rotate independently thereof. Thus, rotation 24 of drive shaft 04 and, simultaneously, of eccentric elements 14a and 14b can be translated into an alternating movement of respective support bars 16 and thus of transverse sealing jaws 13a and 13b.

(7) Together with coupling element 15 and support bar 16, eccentric elements 14a and 14b disposed on drive shaft 04 form a translation mechanism which translates rotation 24 of drive shaft 04 into an alternating contrary movement of transverse sealing jaws 13a and 13b. The translation mechanism with transverse sealing jaws 13a and 13b is part of transverse sealing unit 11. A drive motor 02 realized in the manner of a servomotor and comprising a base 03a and a stator 03b is provided for driving drive shaft 04. Drive motor 02 is realized in the manner of a servomotor in which the actual position, namely rotation angle φ, and actual torque M can be measured using a drive controller, which is not shown in FIG. 1.

(8) FIG. 2 shows a diagram relating to the recording of a target position, namely target rotation angle φ, which is associated with a target torque M. To record the corresponding value of target rotation angle φ, the entire tubular bag machine including transverse sealing unit 01 is first calibrated and film tube 09 used for the tubular bag production process is moved between transverse sealing jaws 13a and 13b. Then, the drive control system sets target torque M.sub.Soll for transverse sealing unit 01. Once torque value M.sub.Soll has been reached, actual rotation angle φ.sub.1st is determined by the position sensor system of the servomotor and the thus determined actual rotation angle φ.sub.1st is stored in the drive control system as target rotation angle φ.sub.Soll. As illustrated in FIG. 2 in a schematic and exemplary manner, the value pair M.sub.Soll and φ.sub.Soll lies on a spring characteristic curve which represents the spring stiffness of the transverse sealing unit.

(9) FIG. 3 shows the diagram according to FIG. 2 with the addition of two tolerance thresholds 30 and 31. Said two tolerance thresholds 30 and 31 form a corridor around the value of target rotation angle φ.sub.Soll. During production of the tubular bags, the resulting value pairs of the reached target torque M.sub.Soll and the resulting actual position are permanently monitored parallel to the process. In FIG. 3, examples of two such value pairs 32 and 33 are displayed. In the case of value pair 32, the actual position after reaching the target torque M.sub.Soll is slightly above the value of target rotation angle φ.sub.Soll but still below tolerance threshold 30. Consequently, no error has been reported yet in this case because the deviation error is still relatively small.

(10) In the case of value pair 33, the actual rotation angle upon reaching of target torque M.sub.Soll is already outside the tolerance corridor, which is why an error has been reported.