EP0639529B1 - Device and method for screwing screwclosures - Google Patents

Description

Device and method for screwing on screw closures, in particular screw closures with a tamper-evident locking ring that spans a transfer ring on the bottle neck, comprising a rotationally drivable screw cap that engages or spills over the screw cap and is arranged at the free front end of a drive shaft, the drive shaft via an electromagnetic clutch can be coupled to the rotary shaft of a rotary drive to form a drive clutch, the screw attachment being mounted so that it can move up and down to engage the screw cap, a brake magnetic clutch being arranged between the drive shaft carrying the screw attachment and a rotationally fixed clutch housing surrounding the electromagnetic clutch is, and wherein a sensor for detecting the screwing torque is provided.

Furthermore, the invention relates to a method in which it is provided that the rotary drive is braked towards the end of the screwing-on process by an electromagnetic brake clutch.

Such a device and such a method are known from DE 41 31 910 A1 by the applicant.

The invention is based on the fact that - as already discussed in the generic document - with conventional screwing devices and methods it is possible to automatically screw a closure cap loosely placed on a filled container. The rotary drive and the electromagnetic clutch are designed in known arrangements so that the screwing resistance is reliably overcome when screwing on. In order to achieve this, the torque must be set relatively high, so that it is guaranteed that irregularities, for example on the threaded neck of glass bottles, and the increased Resistance when slipping on the tamper-evident ring on the cap can be reliably overcome using a transfer ring on the bottle. However, this also means that in some cases the closing torque is so high that the screwed-on closure can hardly be opened by older or frail people.

The solution to this problem has been considerably improved by the measure according to DE 41 31 910 A1 of the applicant. Then an electromagnetic brake clutch was installed, which was fully activated depending on the reaching of a maximum distance or time during the screwing-on process or also a certain torque threshold in order to bring the torque transferred to the screw cap to zero as quickly as possible.

Proceeding from this, the object of the invention is to improve the generic device and the generic method even further, so that this also meets the highest requirements for a defined closure torque, as are made in particular by the pharmaceutical industry when unscrewing closure caps for pharmaceutical bottles can be.

This object is achieved in that a device for detecting the lowering path of the screw attachment is provided, that the sensor for detecting the torque is designed as a torque sensor continuously detecting the torque present in each case, that the torque transmitter is followed by a controller such that the output signal of the torque transmitter is supplied to the controller as the actual value of the torque, an output of the controller being connected to the brake magnetic coupling in order to compare the stored setpoint value or setpoint curve dependent on the screw-on travel distance with the actual values supplied by the torque transmitter and by Adjust devices for influencing the current strength or current duration or current pulse duration of the brake magnetic clutch to the predetermined target values.

With this configuration, the magnetic brake clutch is not only used to maximize the torque from a certain distance to bring quickly to zero, but a very defined torque is adjusted so that a predetermined locking torque is reliably achieved. In this way, a fundamentally improved reproducibility of the closing process can be achieved, whereby on the one hand it is ensured that the closure cap is always completely screwed on and on the other hand an excessive closing torque which prevents reopening is avoided.

In a further embodiment of the invention, a device for continuously detecting the lowering path is provided, the output of which is connected to an input of the controller. This device is advantageously designed as an incremental encoder, it being possible for a rack to be arranged on the outside of the housing of the device, in which a gearwheel of the stationary incremental encoder engages.

The above-mentioned object is also achieved by a method which is characterized in that a desired course of the torque as a function of the screw-on travel distance is stored in the controller, that the lowering travel is detected by means of a corresponding encoder with each individual screw-on process, and that Setpoint torque stored for the respective amount of the lowering path is compared with the actual torque determined by the torque transmitter and the brake clutch is more or less engaged according to the deviation.

The activation of the brake magnetic clutch depending on the required correction can be done so that the amplitude of the current through the magnet windings is changed or that a kind of pulse width modulation is used, so that the effective duration of current is changed by changing the width and, if necessary, plus the height of the pulses can be. In the context of the invention, the control is preferably carried out exclusively via the brake clutch, whereas the drive clutch remains permanently and uniformly energized. This naturally presupposes that the braking effect of the brake clutch and accordingly, their dimensioning is such that, despite the current being supplied to the drive clutch, braking to zero torque is possible, if necessary.

Advantageously, it is provided that the control of the torque starts at the lowering distance that corresponds to the overlapping of the lower edge of the transfer ring by the lower edge of the tamper-evident ring on the closure cap. Up to this point in time or waypoint, a relatively high torque has to be used in order to overcome irregularities in the thread on the one hand and the thickening caused by the transfer ring on the other hand. The required torque then drops significantly, and the control according to the invention is then used to achieve the desired locking torque.

One can advantageously proceed in such a way that after the start of the regulation, the screwing torque is initially kept constant and then increased to a final value corresponding to the desired closing torque. This makes it possible to set a defined state over a certain distance or a certain period of time after the phase of greatly increased torque, until the final value of the closing torque is then set based on this defined level.

After this predetermined closing torque value has been reached, the control is advantageously set and transitioned from controlled operation to a state in which the maximum braking effect is used and the torque acting on the screw cap is brought to zero. Accordingly, it is ensured that the screw cap has a defined end position and at the same time a defined closing torque.

In an advantageous embodiment of the method according to the invention it can be provided that an output of the controller with a memory or recorder for logging the torque values achieved with each individual screwing operation. Accordingly, when bottles with high-quality products are closed, particularly in the pharmaceutical sector, a high level of quality assurance of the filled bottles can be achieved, which was not possible with conventional closing techniques.

Finally, within the scope of the method according to the invention it is still possible that if, due to the individual circumstances, the intended closing torque is not reached in a particular screwing operation, an error message is given and, if necessary, an ejector is activated to reject the bottle which has not been closed properly.

Fig. 1

einen schematischen Längsschnitt durch den mechanischen Teil einer erfindungsgemäßen Vorrichtung,

Fig. 2

ein Diagramm zur Veranschaulichung des Drehmomentenverlaufs in Abhängigkeit von dem Aufschraubweg bzw. den verschiedenen Aufschraubphasen und

Fig. 3

ein Diagramm zur Veranschaulichung des Drehmoments in Abhängigkeit von dem Verschraubweg längs des Flaschenhalses.

The invention is explained in more detail below on the basis of a preferred exemplary embodiment in conjunction with the drawing. Show

Fig. 1

2 shows a schematic longitudinal section through the mechanical part of a device according to the invention,

Fig. 2

a diagram illustrating the torque curve as a function of the screw-on path or the different screw-on phases and

Fig. 3

a diagram illustrating the torque as a function of the screwing along the bottle neck.

To this extent, in accordance with the embodiment according to the generic DE 41 31 910 A1, the device shown in FIG. 1 comprises a screw attachment 1, which is dimensioned such that it can grip a screw cap, not shown in FIG. 1, placed loosely on a container neck . The screw attachment is fastened to a drive shaft 2, which is mounted in a first housing part 5 via a ball bearing 3 for absorbing the radial forces and an axial ball bearing 4 for absorbing the axial forces. By two star couplings 29 and 30 is the Drive shaft 2 with the drive shaft 12 rotatably connected with an intermediate torque sensor.

This torque transmitter Md is formed by a product which is commercially available as such and is therefore not shown in detail. Because of its arrangement, this torque transmitter Md can detect the screw-on torque that is transmitted by the screw-on device 1.

A magnetizable disc 6 with a flange extension comprising the drive shaft 12 forms, together with a coil 8, which is supplied with current via a schematically indicated line 9, an electromagnetic brake clutch 10. The magnetizable disc 6 and the flange extension 7 are with the drive shaft 12 non-rotatably connected. The coil 8 is arranged rotatably relative to the housing part 5.

Above the coil 8, a coil 13 is arranged, which is also mounted in a rotationally fixed manner with respect to the housing part 5, and in which a magnetic flange part 14 connected to the shaft 28 in a rotationally fixed manner engages.

A corresponding flange part 16 is mounted over a narrow horizontal gap, separated from the flange part 14 by means of an axial ball bearing 15, and is connected in a rotationally fixed manner to the shaft 17 by means of a tooth coupling 11 with a rotary drive (not shown).

The two flange parts 14 and 16 together with the coil 13 form an electromagnetic clutch 20. This electromagnetic clutch 20 transmits a defined torque corresponding to the current supplied via a line 21 to the coil 13 from the shaft 17 to the drive shaft 12 and via the torque transmitter Md the shaft 2 which carries the screw attachment 1. Accordingly, the electromagnetic clutch 20 functions as a drive clutch.

For screwing on, after a pharmaceutical bottle with a loosely attached screw cap has been positioned below the device shown in the drawing, for example, the housing 5 or 19 is lowered over the base plate 22 in the direction of the arrow 23, the electromagnetic Clutch 20, that is, the drive clutch, is activated by switching on the current through the coil 13. Accordingly, the screw attachment 1 rotates and the screw cap is screwed on, the housings 5, 19 being continuously lowered together with the rotary drive. The progress of the lowering process is detected by a rack 25 attached to the outside of the base plate 22, which drives a gear 26 of an incremental encoder, not shown in the drawing, the gear 26, as indicated at 27, being mounted in a stationary manner.

The course of the screwing-on process and its termination by the brake clutch 10 in cooperation with the control according to the invention based on the actual value detection by the torque transmitter Md is described in more detail below in connection with FIGS. 2 and 3.

In Fig. 2, the screw-on torque F is a function of the screw-on distance s, i.e. from the progressive lowering movement of the screw head 1, as detected by the incremental encoder via the gear 26.

Below the axis s, arrows indicate whether a rotary or lowering or lifting movement is taking place. The respective phase of the screwing process is also shown below the axis s. The screwing-on process is described with reference to the screwing on of a closure cap with a tamper-evident locking ring and a drip insert, which is screwed onto a bottle which has an external thread on the bottle neck and a transfer ring which, after unscrewing during the closing process and after unscrewing the closure cap during use holds back the tamper-evident ring on the bottle neck in a manner known per se and thus makes it recognizable that the bottle has already been opened once in use.

Starting from the position shown in Fig. 2a, the cap is lowered into the position shown in Fig. 2b, from which the screwdriver 1 is engaged and the cap rotates, so that their internal thread comes into engagement with the external thread of the bottle neck, which increases the torque. An additional increase in torque is due to the fact that, starting from this phase, the drip insert is pushed into the inside of the bottle neck and reaches the position shown in FIG. 2c.

In the phase shown in FIG. 2c, a further increase in the torque occurs in that the tamper-evident ring 29 is pushed over the edge of the transfer ring until the lower edge of the tamper-evident ring 29 engages over the lower edge of the transfer ring. In this phase, the required torque suddenly drops, as shown between phases c and d in the drawing, and the control according to the invention is used here starting from this way point, with phase d regulating to a constant torque value is screwed further down and then in phase e the torque value is increased until the desired locking torque. After this value has been reached, the control process implemented by applying the brake clutch 10 to a greater or lesser extent is terminated and the brake is activated to the maximum, so that the torque is set to zero and, as indicated by the arrow pointing upward, the screw attachment is moved upward becomes.

A - B:

Der Verschluß wird bis über den Transferring mit eingestelltem maximalen Drehmoment und verhältnismäßig hoher Drehzahl ohne Einschalten der Bremse verschraubt.

B - C:

Der Transferring wird überschritten. Die Drehzahl wird auf ca. 10 % des vorherigen Wertes abgebremst, um die Fliehkraft zu reduzieren.

C - D:

Mit niedriger Drehzahl wird bis auf den eingestellten Drehmomentwert geregelt. Das Drehmoment steigt aufgrund der Pressung an. Durch die Regelung über die Erfassung des Drehmoments und die Aktivierung der Bremse wird das eingestellte Drehmoment bis zum Erreichen des Endes des Verschließvorganges gehalten.

D - E:

Um ein Überschrauben zu verhindern, wird die Bremse voll aktiviert.

In Fig. 3, the torque curve shown schematically in Fig. 2 is again shown depending on the geometry of the bottle neck or the cap. Again, the phases described above must be taken into account as follows:

A - B:

The closure is screwed up over the transfer ring with the set maximum torque and relatively high speed without the brake being switched on.

B - C:

The transfer ring is exceeded. The speed is braked to approx. 10% of the previous value in order to reduce the centrifugal force.

C - D:

At low speed, it is regulated up to the set torque value. The torque increases due to the pressure. By regulating the acquisition of the torque and activating the brake, the set torque is held until the end of the closing process.

D - E:

The brake is fully activated to prevent screwing.

Claims (10)

1. An apparatus for the screwing on of screw closures, in particular of screw closures having a tamperproof safety ring overlapping a transfer ring on the bottle neck, comprising a screwing-on head (1) drivable to rotate and seizing or, respectively, overlapping the screw cap and which is disposed on the free front end of a drive shaft (2), the drive shaft (2), by way of an electromagnetic coupling (20), being connectable to the shaft, driven to rotate, of a rotary drive for the formation of a drive coupling, the screwing-on head (1) being reciprocatingly supported for engagement with the screw cap, a magnetic brake coupling (10) being disposed between the drive shaft bearing the screwing-on head and a coupling housing disposed against rotation and surrounding the electromagnetic coupling (20), and a sensor being provided for the detection of the screwing torque, characterized in that a device is provided for detecting the distance of lowering of the screwing-on neck in that the sensor for detecting the torsional moment is a torque indicator (Md) continuously detecting the torsional moment occurring in each case, in that a controller is disposed downstream of the torque indicator (Md) in such a way that the output signal of the torque indicator (Md) is fed as an actual value of the torsional moment to the controller, an output of the controller being connected with the magnetic brake coupling (10), for controlling on the preset desired values by comparison of a stored desired value or desired value course depending on the screwing-on distance with the actual values furnished by the torque indicator (Md), and by devices for acting on the intensity or on the duration or pulse duration of current exerted on the brake coupling (10).
2. Apparatus according to claim 1, characterized in that a device for the continuous detection of the lowering distance is provided, the output of which is connected with the controller.
3. Apparatus according to claim 2, characterized in that the device for the detection of the lowering distance is an incremental transmitter.
4. Apparatus according to claim 3, characterized in that on the outside of the housing (5) of the apparatus, a rack (25) is disposed, with which a pinion (26) of the stationary incremental transmitter engages.
5. Method for screwing on screw closures by means of an apparatus according to claim 1, characterized in that a desired course of the torsional moment in dependence on the screwing-on distance is stored in the controller, in that the lowering distance is detected for each individual screwing-on operation by means of a corresponding indicator and in that the desired torque stored for the respective lowering distance is compared with the actual torque detected by the torque indicator and in that the brake coupling is engaged more or less depending on the deviation.
6. Method according to claim 5, characterized in that the control of the torsional moment commences at such a lowering distance as corresponds to the overlapping of the lower edge of the transfer ring by the lower edge of the tamperproof safety ring of the closure cap.
7. Method according to claim 6, characterized in that, once the control has been started, the screwing-on torque is first kept constant and then increased to a final value corresponding to the envisaged closing torque.
8. Method according to claim 5, characterized in that, after this preset closing torque value has been reached, the control is stopped, and by utilization of the maximum braking effect, the torsional moment acting on the screw cap is set toward zero.
9. Method according to claim 5, characterized in that an output of the controller is connected with a memory or recorder for recording the torque values realized in each individual screwing-on operation.
10. Method according to claim 5, characterized in that, the provided closing torque not being reached because of the individual facts during a certain screwing operation, an error report is emitted and, possibly, a discharger is activated for sorting out the bottle that is not regularly closed.

Images