EP2029468B1 - Method for determining the final cap torque required for capping bottles or like containers - Google Patents

Description

The invention relates to a method according to the preamble of claim 1. In containers, for example bottles, with screw caps, it is desirable for the consumer to open such closures only a certain force, i. only has to apply a certain maximum opening torque, so such screw caps are not closed too tight. However, it is also imperative that screw caps are sufficiently tightly bolted to the respective container to achieve a tight seal and, for example, escape of contents, e.g. Carbonic acid, but also to prevent the ingress of foreign substances, such as harmful germs reliably in the original sealed container.

Due to the properties of the combination screw cap and container on the one hand, and due to the structure and control of the motor-driven closing units used for closing the moment or opening moment required for opening a container by the maximum torque (hereinafter closing end torque) when screwing or Closing the container determines.

In order to meet the above requirements in terms of production safety and convenience, it is necessary to set the maximum closing end torque accordingly. Furthermore, it is also desirable to keep the opening moments of all sealed containers within close tolerance limits.

It is known to empirically adjust the closing end torque in the case of motor-driven closing units of a closing machine, for example by closing a plurality of containers with the respective closing unit to be set in a setting or adjusting phase and subsequently reopening them by hand, in which case the opening moment is opened suitable measuring device (eg torque meter) is measured. A generic device is in the WO 2004/085304 shown. By comparing the nominal value of the opening torque with the measured actual value of this torque, the respective screwing or closing unit is then possibly adjusted taking into account the measured values of further tests. The disadvantage here is, inter alia, that the measurement by hand by trained personnel is required for this setting, which is also able to draw conclusions from the measured values for the setting of the respective closing unit. A further disadvantage is that the measurement results in Opening the container during the adjustment phase are very inaccurate, and indeed because of the manually executed opening movement, which basically can not be constant or continuous.

The object of the invention is to provide a method with which the adjustment can be done purely by machine. To solve this problem, a method according to claim 1 is formed.

The method according to the invention has the advantage that virtually no personnel, in any case no personnel is required for the adjustment of several Verschraub- or Verschließeinheiten a sealing machine, which must perform special measurements by hand.

Furthermore, the method according to the invention enables a comparison of the screwing or closing units in a much shorter time and leads to reproducible results at lower costs.

Further developments of the invention are the subject of the dependent claims.

Fig. 1

eine mit einem Schraubverschluss verschlossene Flasche;

Fig. 2

in vereinfachter Darstellung und in Draufsicht eine Verschließmaschine umlaufender Bauart;

Fig. 3

eine der Verschraub- oder Verschließeinheiten der Verschließmaschine der Figur 2, mit Verschraubspindel und mit zugehörigem Antrieb;

Fig. 4

eine schematische Darstellung eines dreigängigen Schraubverschlusses mit Zweidrittelwindungen;

Fig. 5

Diagramme der Winkelgeschwindigkeit sowie des Drehmomentes beim Verschließen, in Abhängigkeit vom Dreh- bzw. Schraubwinkel.

The invention will be explained in more detail below with reference to the figures of exemplary embodiments. Show it:

Fig. 1

a bottle closed with a screw cap;

Fig. 2

in a simplified representation and in plan view of a closing machine of rotating design;

Fig. 3

one of the screwing or closing units of the closing machine of FIG. 2 , with screw spindle and with associated drive;

Fig. 4

a schematic representation of a three-threaded screw cap with two-thirds turns;

Fig. 5

Diagrams of the angular velocity and the torque during closing, depending on the turning or helix angle.

In the figures, 1 is a container in the form of a bottle, which by a screwed, in the fig1 shown cut closure 2 is closed in the form of a cap. The closing of the bottles 2 takes place in the manner known to the person skilled in a sealing machine 3, of which in the FIG. 2 only a schematic view of a rotor 4 driven in rotation about a vertical machine axis is shown, on whose circumference a plurality of closing positions 5 are formed. The bottles 1 to be closed are each fed to a closing position 5 at a bottle inlet 3.1 of the capper. The sealed bottles 1 are fed to a bottle outlet 3.2 for further use.

On the angular range of rotation (arrow A) of the rotor 4 between the bottle inlet 3.1 and the bottle outlet 3.2 a closure 2 is placed on each bottle 1 and this then screwed onto the thread formed at the respective bottle mouth 1.1, with a closing end torque , which among other things taking into account various bottle or closure parameters, such as number of threads and the pitch of the thread 1.1, taking into account material parameters, etc. conditional on an opening moment, which must be applied by the user when opening the bottle 1 and the closure 2 and thus a Function of the closing moment is.

For applying the closures 2 on the bottles 1, each Verschließposition 5 in the manner also known to the person skilled in a Verschließeinheit 6 with screw or capping head 7 with associated drive, screwed with the (screw) the respective closure 2 on the thread 1.1 at the bottle mouth becomes. Each closing unit 6 is individually controllable, namely to achieve a, corresponding to the respective desired opening torque closing end torque during closing, as will be explained in more detail below. The drives assigned to the individual closing units 6 are preferably those drives which permit an individual adjustment of rotational speeds, directions of rotation and / or torques independent of the other drives. This may be e.g. to act known servo, stepper or synchronous motors in which the desired operating parameters can be set and realized in a controlled and / or controlled manner.

In one embodiment of the method according to the invention, for example, an individual adjustment (tuning) of the individual closure units 6 and their drives, in the form that initially taking into account known parameters such. B. such concerning the formation and / or geometry of the thread 1.1, the design and geometry of the closures 2, the type of materials used, etc., as well as taking into account the desired opening moment the closing torque or the torque corresponding thereto at the screw or closing head 7 is calculated, for example on the basis of a mathematical model, which also maps or takes into account the mechanical and / or electromagnetic conditions of the closing units 6.

With this torque setting, an individual adjustment of the closing units 6 is then carried out at each closing position 5, in such a way that in this tuning, a bottle 1 is closed with the calculated moment setting or with this calculated moment and then opened again. The occurring moments, speeds and angles of rotation are detected by a corresponding sensor, recorded or stored for subsequent calculations and optimizations.

Specifically, the measurement of the moments can be done by suitable devices, such as torque boxes, strain gauges, but also indirectly by measuring the motor current of the drive of the respective closing unit 6. In principle, it may be sufficient to detect and store in each case the maximum value of the torques, rotational speeds and / or rotational angles.

When determining the torques by measuring the motor current, for example, the maximum value of the current at the end of the closure (as a measure of the closing end torque) and the maximum value of the current during opening (as a measure of the opening moment) are determined. Furthermore, the opening speed is determined. On the basis of a current-torque characteristic of the drive motor specific to the respective drive motor and taking into account the existing gear ratio, the torque exerted on the closure 2 by the closing unit 6 or its head 7 can then be calculated with sufficient accuracy during closing and opening.

The original closing moment, for example, based on the model calculation or empirically determined, is then corrected individually for each closing unit 6 on the basis of the measured values determined during opening during the adjustment or tuning phase, in particular on the basis of the determined opening torque such that the result from the closing end torque Opening torque corresponds to the desired value. This correction takes place, for example, by multiplying the originally calculated or empirically determined closing end torque by a correction factor which corresponds to the quotient of the setpoint value for the opening moment and the actual value of the opening moment determined during the adjustment phase.

After the adjustment or tuning of all Verschließeinheiten 6 at the Verschließpositionen 5, ie after completion of the adjustment phase is carried out in a subsequent production phase, the closure of the bottles 1 with the closures 2 by screwing in such a way that for each bottle 2 an opening torque with the desired value.

In this case, in particular, it is possible to adapt the individual closing units 6 so that the original closing end torque for the closing elements 6 of all closing positions 5 is stored as a common value in a control unit 8 and for each closing unit 6 individually the correction or tuning factor.

In electric drives with DC machine-like performance, the current-torque characteristic is usually dependent on the speed, so that in the determination of the torque, in particular the maximum opening torque, the speed of the respective closing device 6 and the head 7 is taken into account.

Furthermore, the torque is also dependent on the respective installation situation and the specific mechanical conditions of each closure unit 6, so that it is at least useful for improving the balance, by measuring the idle current, to determine the idling torque of each closing unit 6 and in the memory of the Control device 8 store individually for each closing unit 6, so that this idle torque then in the determination of the correction or tuning factor of each closing and / or later in the production phase when closing the bottle 1 with the corrected output value of the closing end torque in addition to the respective correction factor can be taken into account.

For the determination of the tuning factor, it is only necessary to loosen the respective closure 2 on the respective bottle 1, to which a rotary movement by a small angle, for example 90 °, is sufficient. By lowering the speed of the rotor 4 of the closing machine 3 during the determination of the tuning factor, it is possible to close the relevant bottle 2 during its further passage through the capping machine 3 after opening again, so that also incurred during the adjustment waste is avoided ,

In the described adjustment or in the described determination of the correction factor, it is also possible to take into account measured values which were determined manually outside the capping machine, for example by measuring the opening torque. Furthermore, by comparing different opening methods, namely for example the opening through the respective closing unit 6 and through the opening outside the closing machine 3 by hand, further factors or findings can be determined which are used for the adjustment or for the determination of the corrector or tuning factor can be.

The screwing angle required for screwing the respective closure 2 onto a bottle 1 until final closure is decisively influenced by the geometry of the closure 2 or of the thread 1.1. The following example of a three-speed shutter with two-third turns in plan view illustrates this.

If N _G denotes the number of threads and N _W the number of turns of a thread, then the thread pitch designated T corresponds to the angle between two successive thread starts and is calculated from the ratio of the full angle to the number of threads: $$\mathrm{T}=\mathrm{2}\mathrm{\pi }/{\mathrm{N}}_{\mathrm{G}}$$

The maximum bolting angle corresponds to the number of turns of a gear in rad: $${\mathrm{\phi }}_{\mathrm{V}.\mathrm{Max}}=\mathrm{2}\mathrm{\pi }\cdot {\mathrm{N}}_{\mathrm{W}}$$

The minimum bolting angle is smaller by one pitch than the maximum: $${\mathrm{\phi }}_{\mathrm{V}.\min }=\mathrm{2}\mathrm{\pi }\cdot {\mathrm{N}}_{\mathrm{W}}-\mathrm{T}=\mathrm{2}\mathrm{\pi }\left[{\mathrm{N}}_{\mathrm{W}}-\mathrm{1}/{\mathrm{N}}_{\mathrm{G}}\right]$$

The following example of a three-speed shutter with two-third turns in plan view illustrates this. The superimposed threads have been drawn into each other for better representation, with the white point at the beginning of the thread and the black dot corresponds to the threaded end.

The screwing process can now be imagined so that an imaginary point of the bottle thread can attack at any point of the outermost lines. By the rotation in the mathematically negative sense is screwed up. If the imaginary bottle thread point reaches the end position shown in black, the tension between the cap and bottle begins.

The FIG. 5 shows in the diagrams a and b the typical course of the angular velocity of the respective closing unit 6 and the head 7 and the torque transmitted to a closure 2 when closing a bottle 1 with the closure during the production phase.

As shown in the diagram a, initially takes place at a substantially constant rotational or angular velocity w the assumption of the respective closure 2 by a closing unit 6 and then placing the closure 2 on the respective bottle 1. The screwing then takes place at an increased angular velocity ω, wherein also according to the diagram b, the torque with increasing Verschraubwinkel φ increases. As soon as a switching moment is reached, the rotational speed w of the closing device 6 is reduced, until a reduction to the value zero takes place when a closing end torque is reached, namely while maintaining the closing end torque, so that a further tightening of the closure 2 at a Alignment of the threads can be done and the shutter 2 is then turned on with the desired opening moment corresponding closing end torque on the bottle 1 and on the thread 1.1.

The invention has been described above by means of an embodiment. It is understood that numerous changes and modifications are possible without thereby departing from the spirit of the invention.

For example, it was assumed above that the adjustment or tuning takes place each time before a subsequent production phase. In principle, it is also possible to carry out this adjustment, for example, continuously or at specific time intervals during a production phase. This periodic adjustment during a production phase then has the advantage that changes in the operating parameters occurring during the adjustment during production, for example due to wear, are taken into account, in particular at the screwing and closing units 6 or their heads 7, and thus a particularly high production reliability results.

LIST OF REFERENCE NUMBERS

1

bottle

1.1

Thread on the bottle mouth

2

cap-like closure

3

sealing

4

rotor

5

closing positions

6

Closing unit with screw spindle

7

Drive the sealing unit

8th

control unit

Claims (11)

1. Method for determining the cap torque required for capping bottles or the like containers with screw caps (2), using a motor-driven capping unit (6) of a capping machine (3), with which, in a phase of adjustment, at least one cap (2) of a previously capped container (1) is reopened, with in this situation at least the opening torque required for the said reopening being determined as the corrective value and the subsequent capping of the containers (1) being carried out by the capping unit (6) with a final cap torque that takes into consideration this corrective value, characterised in that in the phase of adjustment the at least one cap (2) is reopened by the capping unit (6), and in this situation at least the opening torque of the capping unit (6) and/or of a drive of the capping unit (6) required for this reopening is determined as a corrective value.
2. Method according to claim 1, characterised in that, at the beginning of the phase of adjustment, the no-load torque of the at least one capping unit (6) is determined.
3. Method according to claim 2, characterised in that the no-load torque is taken into consideration in the determination of the corrected final cap torque.
4. Method according to claim 2 or 3, characterised in that the no-load torque is taken into consideration in the determination of the opening torque during the phase of adjustment.
5. Method according to any one of the preceding claims, characterised in that, from the measured values determined at the reopening of the at least one container (1) during the phase of adjustment, a corrective factor is formed, with which a final cap torque is corrected, this torque being original, empirical, or determined by calculation.
6. Method according to any one of the preceding claims, characterised in that, with the use of one capping machine (3) with at least two capping units (5), the adjustment for each capping unit is carried out individually.
7. Method according to claim 6, characterised in that, for each capping unit, the no-load torque and/or the corrective factor are determined and/or stored individually.
8. Method according to any one of the preceding claims, characterised in that in each case a production phase follows on from a phase of adjustment, in which the containers (1) are capped with the corrected final cap torque.
9. Method according to any one of the preceding claims, characterised in that, during the production phase, in each case an adjustment takes place continuously or at predetermined time intervals.
10. Method according to any one of the preceding claims, characterised in that the corrected final cap torque is determined by the multiplication of an initial final cap torque by the corrective value.
11. Method according to any one of the preceding claims, characterised in that the corrective value is formed as a quotient from a desired value for the opening torque and the value of the opening torque measured during the phase of adjustment.

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