Capping device and method for tightening screw caps

Abstract

To provide a novel lid closing apparatus for closing a screw cap, the apparatus comprising a motor and a power transmission mechanism for transmitting force to the screw cap from the motor by the power transmission mechanism.SOLUTION: A lid closing apparatus of the present invention comprises a control unit configured to adapt the operation of a motor dynamically by utilizing a measured actual value of an operating parameter of the motor such as a target lid closing torque and an actual lid closing torque model.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the technical field of devices for automatically tightening screw caps on containers, for example in a motor-driven manner, and in particular to a capping device for tightening screw caps, which comprises a motor and a power train and is configured to transmit force from the motor to the screw cap via the power train. [Background technology]

[0002] It is known that the screw cap is tightened by the motor by appropriately transmitting the force of the motor, so that the screw cap rotates on a thread, for example a thread on the opening of a container. In this case, as an example, a maximum motor torque is specified. This variable can be easily detected with existing systems and the motor can be controlled so that the maximum motor torque is not exceeded. In this specification, the motor torque is the torque output by the motor. When transmitted to the cap, this motor torque is divided at least into the intrinsic torque of the power transmission mechanism and the torque acting on the screw cap. The degree of sealing after the screw cap is tightened can be quantified, for example, by the actual capping torque. The actual capping torque depends on the torque acting on the screw cap during the capping process. Furthermore, the properties of the screw cap and its counterpart, in particular the respective threads, are also important in the capping process. In order to determine the influence on the actual capping torque, the properties of the threads can be quantified in the form of a counter torque. For example, in this specification, the coefficient of friction of the cap and its counterpart, the shape of the threads or the elasticity of the respective materials can affect the magnitude of the counter torque. The actual capping torque depends not only on the torque acting on the screw cap but also on this counter torque.

[0003] In principle, it is desirable for the actual capping torque to deviate as little as possible from a predetermined target capping torque, however known systems cause the actual capping torque to vary over a relatively wide range. Summary of the Invention [Problem to be solved by the invention]

[0004] The object underlying the present invention is therefore to provide a capping device and a method for tightening screw caps, whereby the mean deviation of the actual capping torque from the target capping torque is reduced. [Means for solving the problem]

[0005] This object is achieved by the subject matter of the independent claims. Preferred embodiments are set forth in the dependent claims.

[0006] According to the present invention, the capping device mentioned at the beginning is provided with a control unit configured to dynamically adapt the operation of the motor using actual measured values ​​of the motor's operating parameters, such as the actual motor speed, the target capping torque and an actual capping torque model.

[0007] Measuring the actual capping torque during operation is technically difficult. The inventors have also found that a significant contribution to the deviation is due, inter alia, to inertia and friction that arise in the drive train and can cause a certain amount of overrun. Even if the actual capping torque is measured during operation and the motor is stopped when the target capping torque is reached, the capping torque will increase due to the overrun of the drive train by an amount that depends on various system and / or operating parameters. Therefore, correction by a simple correction value does not always bring about the desired improvement. Furthermore, deviations in the properties of the cap and / or its counterparts, for example deviations due to the respective materials used, also play a role, since the generation of the counter torque over time due to them, which occurs respectively especially towards the end of the capping process, varies with the capping process due to such deviations.

[0008] However, the claimed dynamic adaptation makes it possible to reliably reduce the deviation of the actual capping torque from the target capping torque.

[0009] In this specification, the target capping torque means a predetermined value that the actual capping torque should have after the completion of the capping process. The target capping torque may be stored anywhere, for example, in the storage medium of the capping device and in a separate storage medium. The target capping torque may be stored by a user. The height and the format or unit specified for the target capping torque depend on the actual use case and may be selected in an appropriate manner by a person skilled in the art.

[0010] In addition to the motor and the power transmission mechanism, the capping unit may also comprise elements that directly interact with the cap, such as a screw head configured for holding the cap and / or for directly transmitting forces during the capping process. The motor may be, for example, an electric motor. The power transmission mechanism may, for example, include a gear unit.

[0011] A screw cap may comprise a cap, for example a lid, for a container, the cap being provided with a thread, in particular an internal thread.

[0012] Dynamic adaptation in this context means performing the control, for example by a closed-loop control process, which has actual values ​​of the motor's operating parameters supplied to the motor and adjusts the set values ​​of the motor's operating parameters during the entire capping process such that a predefined target capping torque is achieved. In particular, the capping device may be configured such that the measurement and adaptation of the motor's operation, in particular the calculation of the actual capping torque by means of an actual capping torque model, is performed continuously.

[0013] In particular, a continuous calculation of the intrinsic torque of the drive train and the actual capping torque derived therefrom can be performed and the values ​​of the operating parameters can be adjusted based on this calculation. In the simplest case, the actual capping torque model can generate a value of the actual capping torque by forming the difference between the motor torque (torque output by the motor) and the intrinsic torque of the drive train.

[0014] The actual capping torque model may be configured to provide a modeled actual capping torque that is due to a modeled torque acting on the cap based on the modeled torque.

[0015] In this specification, the torque acting on the cap is the torque transmitted to the cap, which may be due to the motor torque, the inherent torque of the power transmission mechanism, and possibly also due to other system parameters such as friction. The capping torque depends on the torque acting on the cap and the counter torque. The counter torque may depend on the properties of the cap and / or its counterpart, especially their threads, for example as explained above. These properties and parameters may therefore affect the modeled torque acting on the cap and the modeled capping torque.

[0016] The actual capping torque model may be configured to provide the torque acting on the cap utilizing a power train model, which among other things includes a modeled intrinsic torque of the power train.

[0017] The drivetrain model may be configured to provide a value for the intrinsic torque of the drivetrain based on inertia and / or friction within the drivetrain.

[0018] The control unit may be configured to dynamically adapt operation of the motor based on the control loop.

[0019] The control loop may be configured to output a value and / or a range of values ​​and / or upper and / or lower value limits for at least one operating parameter that is set based on an actual measured value of the operating parameter and a predetermined target capping torque as input variables.

[0020] The control loop may be configured to determine a current value of the actual capping torque using the actual capping torque model, and to determine a value and / or a range of values ​​and / or upper and / or lower value limits for at least one operating parameter to be set based on the current value of the actual capping torque and the target capping torque, in particular based on a comparison between the actual capping torque value and the target capping torque value.

[0021] The control loop may be configured to determine a value and / or a range of values ​​and / or upper and / or lower values ​​of at least one operating parameter to be set according to the actual capping torque model, so as to require that when the value of the set operating parameter is set, the value of the actual capping torque approaches the target capping torque.

[0022] The control unit may be configured to set to the motor an operating parameter value that corresponds to the output value, and / or an operating parameter value that is within the range of the output value, and / or an operating parameter value that is below the output upper limit, and / or an operating parameter value that is above the output lower limit.

[0023] The operating parameters that are set may include motor speed and / or motor torque.

[0024] The capping device may be configured to determine, for example, the value of the counter torque due to a screw cap, in particular the above-mentioned counter torque, using the actual capping torque model and using a set or specific set value of the operating parameter, the desired actual value of the operating parameter, and the measured value of the operating parameter.

[0025] The invention also relates to a capper comprising at least one of the abovementioned capping devices. The capper may in particular be configured for continuous operation. The capper, in particular a capper configured for continuous operation, may be configured in the form of a machine comprising a plurality of the abovementioned capping devices. The machine may in particular be configured in the form of a rotary machine and may comprise a plurality of capping devices according to the invention. The capping devices may in this case in particular be arranged on the periphery of a carousel of the rotary machine configured to transport the containers to be sealed. In particular, the capping devices may be arranged at regular intervals on the periphery of the carousel.

[0026] The provision of multiple capping devices is favorable for an increased throughput, and in the case of devices which include multiple capping devices, particularly in rotary machines, it is particularly favorable for this high throughput to utilize a motor to carry out the capping process as quickly as possible, yet accurately, so that the use of the above-mentioned capping devices allows a high throughput, particularly in such machines, combined with high quality.

[0027] The invention also relates to a filling installation, in particular for filling food products, which comprises one or more capping devices as described above, in particular at least one capper as described above, in particular at least one rotary machine as described above.

[0028] The present invention also relates to a method for tightening a screw cap, where a force is transmitted from a motor to a screw cap by a power transmission mechanism for capping purposes, and the operation of the motor is dynamically adapted utilizing actual measurements of operating parameters of the motor, such as actual speed, target capping torque and actual capping torque model.

[0029] The method steps may be performed as a closed-loop control method, i.e. the steps may be performed repeatedly and the values ​​of the operating parameters may be dynamically adapted. The measurement of the actual values ​​of the operating parameters and the adaptation of the operation of the motor may in particular be performed continuously.

[0030] The operation of the motor may in particular be dynamically adapted based on a control loop, which may in particular be configured to output a value and / or a range of values ​​and / or upper and / or lower value limits for at least one operating parameter of the motor based on an actual value of the operating parameter and a predefined target capping torque as input variables.

[0031] The control loop may be configured to determine a current value of the actual capping torque using the actual capping torque model, and to determine a value and / or a range of values ​​and / or upper and / or lower values ​​of at least one operating parameter to be set based on the current value of the actual capping torque and the target capping torque, in particular based on a comparison of the values ​​of the actual capping torque and the target capping torque.

[0032] The control loop may be particularly configured to determine a value and / or a range of values ​​and / or upper and / or lower values ​​of at least one operating parameter to be set according to an actual capping torque model, so as to determine that when the value of the set operating parameter is set, the value of the actual capping torque approaches the target capping torque.

[0033] The method may include setting, by the control unit, to the motor an operating parameter value corresponding to the output value, and / or an operating parameter value that is within a range of the output value, and / or an operating parameter value that is below the output upper limit, and / or an operating parameter value that is above the output lower limit.

[0034] The features and advantages described in relation to the apparatus are also applicable to the method in an analogous manner.

[0035] Further features and advantages are explained below with reference to the exemplary figures. [Brief description of the drawings]

[0036] [Figure 1]1 shows a schematic diagram of a capping device according to one embodiment, which is not to scale. [Diagram 2] FIG. 2 illustrates a control loop according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] 1, a capping device 1 according to an embodiment of the present invention is shown diagrammatically, not to scale. The capping device comprises a motor 2, a power transmission mechanism 3 and a screw-in head 4.

[0038] Furthermore, this figure shows a support 5, which may or may not be part of the capping device, configured to support a container 6, in particular in the working area of ​​the screw-on head.

[0039] Further shown is a screw cap 7 held by a screw head. The screw cap has a thread 7a, where the thread 7a is an internal thread. Here, a cross section of the screw cap is shown to illustrate the thread. The container has a thread 6a at the end to be closed, where the thread 6a is typically an external thread that matches the thread of the screw cap. Needless to say, the lid tightening device is not limited to precisely tightening containers and caps of this type.

[0040] The figure also shows a sensor 8, which may be attached to or integrally formed with the motor. The sensor is configured to measure an actual value of at least one operating parameter of the motor, for example to detect the motor speed and / or the motor torque.

[0041] Further shown is a control unit 9 connected to the sensor via a data link 10, the sensor and the control unit being configured to transmit data detected by the sensor to the control unit. Alternatively, the control unit and the sensor may be integrally formed with each other.

[0042] The control unit is configured to set respective values ​​of one or more operating parameters of the motor. To this end, the control unit may have a data link 11 to the motor. Alternatively, the control unit may be formed integrally with the motor.

[0043] In the following, a method for tightening a screw cap is described which can be carried out in particular with the capping device described above.

[0044] In particular, to fasten the screw cap, the screw cap may be screwed onto a container thread of the container. In this case, the container may be supported, for example, by a support and the screw cap may be held by a screw head. The motor may be operated, for example, under the control of a control unit, and the motor force may be transmitted to the screw cap by a power transmission mechanism, in particular via the screw head. The transmission of the motor force may include transmission and / or deflection of the motor force.

[0045] The operation of the motor is dynamically adapted using actual measurements of the motor's operating parameters, such as the actual speed, the target capping torque and the actual capping torque model, etc. For this purpose, a control loop may be used, such as the control loop described in detail below in connection with FIG.

[0046] For example, the actual capping torque model can be used to determine and output a value and / or a range of values ​​and / or upper and / or lower value limits for at least one operating parameter to be set for the motor based on actual measured values ​​of the operating parameters and a predetermined target capping torque as input variables.

[0047] For example, a set motor speed and / or a set motor torque and / or a maximum value of the motor torque to which the motor torque is limited, ie an upper motor torque limit, can be determined and output.

[0048] The method may comprise the steps of determining a current actual capping torque with the aid of an actual capping torque model and determining a value and / or a range of values ​​and / or upper and / or lower limits for the at least one operating parameter to be set based on the current actual capping torque and the target capping torque. To this end, the actual capping torque may for example be compared with the target capping torque and in particular subtracted from the target capping torque.

[0049] According to the actual capping torque model, a value and / or a range of values ​​and / or upper and / or lower limits of the values ​​of the set operating parameter can be determined so that when the value of the set operating parameter is set, the value of the actual capping torque can be expected to approach the target capping torque.

[0050] The value of the operating parameter set for the motor is a value that corresponds to the output value, and / or a value that is within the range of the output value, and / or a value that is below the output upper limit, and / or a value that is above the output lower limit.

[0051] The above-described method steps are performed as a closed-loop control process, i.e. the steps are performed repeatedly and the values ​​of the operating parameters are dynamically adapted, in particular the measurements, determinations and outputs are performed continuously.

[0052] An exemplary control loop 12 that can be used in the capping device described above for the above-mentioned methods and / or to dynamically adapt the operation of the motor is shown in Figure 2. The control loop includes, among other things, a capping torque controller 13. Here, the controlled variable is the capping torque, and the input variables of the capping torque controller are the target capping torque and the actual capping torque.

[0053] In addition to the capping torque controller, the control loop comprises a section 14, which utilizes an actual capping torque model to determine the actual capping torque from the actual motor speed and the (limited) motor torque and outputs it to the capping torque controller. Here, the section typically also performs modeling of the intrinsic torque of the drive train.

[0054] Needless to say, in general, the features described in the above embodiments are not limited to these particular combinations but may be used in any other combination. [Explanation of symbols]

[0055] 1...lid fastening device, 2...motor, 3...power transmission mechanism, 4...screw head, 5...support, 6...container, 7...screw cap, 6a, 7a...screw portion, 8...sensor, 9...control unit, 10, 11...data link, 12...control loop, 13...lid fastening torque control device, 14...section

Claims

1. A cap fastening device (1) for fastening a screw cap (7), comprising a motor (2) and a power transmission mechanism (3) configured to transmit a force from the motor (2) to the screw cap (7) by the power transmission mechanism (3), The capping device (1) further comprises a control unit (9), said control unit (9) dynamically adapting the operation of said motor (2) using actual measured values ​​of the operating parameters of said motor (2) and a target capping torque and an actual capping torque model; the actual capping torque model provides a torque acting on the cap utilizing a power train model, the power train model including a modeled intrinsic torque of the power train (3); the actual capping torque model provides a modeled actual capping torque attributable to the modeled torque based on the modeled torque acting on the cap; the control unit (9) being configured to dynamically adapt the operation of the motor based on a control loop (12); said control loop (12) being configured to output a value and / or a value range and / or an upper and / or lower limit of said value of at least one operating parameter to be set based on said actual value of said operating parameter and a predefined target capping torque as input variables, said control loop (12) is configured to determine a current value of said actual capping torque by utilizing said actual capping torque model and to determine said value and / or said range of values ​​and / or said upper and / or lower limits of said at least one operating parameter to be set based on said current value of said actual capping torque and said target capping torque, in particular based on a comparison of said value of said actual capping torque with said value of said target capping torque, The capping device (1), characterized in that the device is configured to determine a counter torque due to the screw cap (7) using the actual capping torque model and using a set value of the operating parameter, a desired actual value of the operating parameter, and a measured value of the operating parameter.

2. The capping device (1) according to claim 1, wherein the drive train model provides a value of the intrinsic torque of the drive train (3) depending on inertia and / or friction within the drive train (3).

3. A capping device (1) as described in claim 1 or 2, wherein the control loop (12) is configured to determine the value and / or the range of values ​​and / or the upper and / or lower limits of the operating parameter to be set according to the actual capping torque model, so that when the value of the operating parameter to be set is set, it is possible to determine that the value of the actual capping torque approaches the value of the target capping torque.

4. The lid fastening device (1) according to any one of claims 1 to 3, wherein the control unit (9) is configured to set the motor (2) to a value corresponding to the output value, and / or a value within the range of the output value, and / or a value below the output upper limit, and / or a value above the output lower limit.

5. Capping device (1) according to any one of the preceding claims, wherein the operating parameters that are set comprise motor speed and / or motor torque.

6. A method for tightening a screw cap (7), in which a force is transmitted from a motor (2) to the screw cap (7) by a power transmission mechanism (3) for tightening the cap, The operation of the motor (2) is dynamically adapted using actual measurements of operating parameters of the motor (2), a target capping torque and an actual capping torque model; the actual capping torque model provides a torque acting on the cap utilizing a power train model, the power train model including a modeled intrinsic torque of the power train (3); the actual capping torque model provides a modeled actual capping torque attributable to the modeled torque based on the modeled torque acting on the cap; The operation of the motor is dynamically adapted based on a control loop (12); said control loop (12) being adapted to output a value and / or a range of values ​​and / or upper and / or lower limits for at least one operating parameter of said motor based on said actual value of said operating parameter and a predefined target capping torque as input variables, the control loop (12) is configured to determine a current value of the actual capping torque using the actual capping torque model and to determine the value and / or the range of values ​​and / or the upper and / or lower limits of the values ​​of the at least one operating parameter to be set based on the current value of the actual capping torque and the target capping torque, in particular based on a comparison of the values ​​of the actual capping torque and the target capping torque, the control loop (12) being configured to determine a counter torque due to the screw cap (7) using the actual capping torque model and using a set value of the operating parameter, a desired actual value of the operating parameter, and a measured value of the operating parameter.

7. 7. The method according to claim 6, wherein the control loop (12) is configured to determine the value and / or the range of values ​​and / or the upper and / or lower limits of the operating parameter to be set according to the actual capping torque model, such that when the value of the operating parameter to be set is set, the value of the actual capping torque is required to approach the target capping torque.

8. 8. The method according to claim 7, wherein a control unit (9) is used to set the motor (2) to a value corresponding to the output value and / or a value within the range of the output value and / or a value below the output upper limit and / or a value above the output lower limit.

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