Cutting device, cutting machine and method for inspecting a cutting device

Abstract

Described is a cutting device (1) for providing cuts on a surface of a plastic cap in a cutting apparatus. The cutting device comprises: a blade (2); a sensor (S) configured for detecting a vibrational signal representative of a vibration behaviour of the blade; a control unit, having a memory and a processor, connected to the sensor to receive the vibrational signal and programmed to process the vibrational signal to generate vibration data, and to process the vibration data to generate a blade maintenance signal.

Description

[0001] DESCRIPTION

[0002] CUTTING DEVICE, CUTTING MACHINE AND METHOD FOR INSPECTING A CUTTING DEVICE

[0003] Technical field

[0004] This invention relates to a cutting device, a cutting machine and a method for inspecting a cutting device, in particular for cutting container caps, for example, plastic caps used to close containers such as bottles, for example.

[0005] Background art

[0006] Typically, caps comprise a body and a tamper evident ring and the body is connected to the tamper evident ring by a connecting tear strip; more specifically, when a user twists the cap for the first time, the body is separated from the tamper evident ring and the tamper evident ring remains attached to the neck of the container. In other types of caps such as, for example, those known as "tethered caps", a permanent connecting zone of the tear strip does not tear and keeps the cap body attached to the tamper evident ring; tethered caps are thus prevented from being lost and help reduce littering.

[0007] In both traditional caps and tethered caps, the connecting strip may include a series of slits and bridges, that is to say, tearable connecting zones between the body and the tamper evident ring; alternatively, especially in the case of tethered caps, the connecting strip may include recesses, that is, narrow thickness portions which are thinner than the body and the tamper evident ring and which tear when the cap is twisted for the first time.

[0008] These cuts or the narrow thickness zones may be made during a step of moulding the cap (by compression, injection or both injection and compression), for example, inside the mould itself or by using movable drawers in the mould, or during a step subsequent to moulding, for example by slitting the cap using specific knives or by a material-removal process.

[0009] In this context, patent WO2022175824, in the name of the present Applicant, provides a cutting machine.

[0010] In this field, therefore, in order to ensure that the cuts are made correctly, it is important to inspect the blade which is configured to make the cuts.

[0011] Known in the prior art in this field are inspection systems for checking the quality of the objects.

[0012] Traditionally, inspection is carried out by optical devices.

[0013] The patent document CN102765010A describes a method for detecting the wear state or breakage of a cutting tool intended for use on a hydraulic lathe employed in machining the rotor of an electromechanical system. The method disclosed in CN102765010A involves the use of an acceleration sensor mounted on the tool holder, which measures the vibrations generated during the cutting process. The sensor is installed on the mower bar of the milling machine and detects the vibrations produced during cutting and grinding operations.

[0014] CN102765010A describes the processing of the signal obtained from the sensor, which allows for the analysis of the vibrations to determine the degree of tool wear and to indicate when replacement is necessary.

[0015] In this field, therefore, there is a need for the cutting blade to be inspected during use of the cutting machine.

[0016] However, the prior art machines have some disadvantages and can be improved. In this field, there is a need for a cutting device, a cutting machine and a method for inspecting a cutting device which allow the cutting blade to be inspected in a particularly efficient and reliable manner.

[0017] Disclosure of the invention

[0018] The aim of this disclosure is to provide a cutting device, a cutting machine and a method for inspecting a cutting device to overcome the above mentioned disadvantages of the prior art.

[0019] This aim is fully achieved by the system and method of this disclosure as characterized in the appended claims.

[0020] According to an aspect of it, this disclosure provides a cutting device. The cutting device is configured for providing cuts on a surface of a plastic cap. The plastic cap is inside a cutting apparatus (cutting machine). The cutting device comprises a blade. The cutting device comprises a sensor. The sensor is configured to detect a vibrational signal. The vibrational signal is representative of a vibration behaviour of the blade.

[0021] The cutting device comprises a control unit. The control unit is provided with a memory. The control unit is provided with a processor. The control unit is connected to the sensor to receive the vibrational signal. The control unit is programmed to process the vibrational signal to derive vibration data. The control unit is programmed to process the vibration data to generate a blade maintenance signal.

[0022] In this solution, information about the behaviour of the blade can be obtained easily and effectively using a single sensor which is often used in a cutting machine.

[0023] In an example, the control unit is programmed to process the vibration data to obtain a pattern. The pattern represents the vibration behaviour of the blade. The control unit is operable in a setup configuration and in a monitoring configuration. In the setup configuration, the control unit is programmed to save, as a reference pattern, the pattern generated from the vibration data acquired at a setting instant. In the monitoring configuration, the control unit is programmed to compare a pattern generated from the vibration data acquired at a monitoring instant with the reference pattern, to estimate a deviation between the reference pattern and the monitoring pattern. The control unit may be programmed to generate the blade maintenance signal as a function of said deviation.

[0024] In an example, the control unit is programmed for periodically updating the pattern generated from the vibration data acquired at the monitoring instant.

[0025] This solution allows checking the functioning of the blade in a reliable and effective manner.

[0026] In an example, the control unit is configured to monitor a working period in which the cutting blade has been used starting from the setting instant. In this example, the control unit is programmed to generate the maintenance signal if the working period exceeds a predetermined value.

[0027] In an example, the device includes a tag. The tag has a non-volatile memory, preferably a read-write memory. For example, the tag might be associated directly with the blade, that is to say, the blade is provided with a tag. The tag may contain identification information identifying the blade. The control unit may be configured to detect the blade based on the identification data.

[0028] This solution allows automating the blade inspection process, making it more effective and reliable.

[0029] In an example, the control unit is configured to detect a replacement of the blade responsive to detection of new identification information.

[0030] In an example, the control unit is programmed to store blade information in the tag. For example, such information may include the serial number / code of the blade and / or the type of cut, or other information.

[0031] In an example, the data stored in the tag may include the number of caps cut by the blade and / or the type of cap cut by the blade.

[0032] In an example, the control unit is configured to derive an additional reference pattern upon detection of a maintenance service performed on the cutting blade. The additional reference pattern is representative of the vibration behaviour of the cutting blade.

[0033] In an example, the tag is provided with a memory to contain data relating to the cutting blade.

[0034] In an example, the data relating to the cutting blade stored in the tag includes at least one of the following:

[0035] - a working period in which the cutting blade has been used starting from the setting instant;

[0036] - one or more monitoring patterns of a plurality of monitoring patterns obtained periodically for the cutting blade.

[0037] Preferably, the sensor has a frequency of at least 30 kHz, and more preferably, at least 40 kHz. The higher the frequency, the higher the sensitivity of the sensor.

[0038] In an example, the sensor has a frequency of 30-120 kHz or 40-100 kHz. This range allows balancing sensitivity / calculation power of the sensor.

[0039] In an example, the cutting device includes an upper plate and a lower plate. In an example, the lower plate and the upper plate are placed opposite each other and are spaced apart. In an example, the first cutting blade is interposed between the upper and lower plates. In an example, the sensor is positioned on the upper plate.

[0040] In an example, the control unit is configured to generate an alert in response to the generation of the maintenance signal.

[0041] In an example, the setting instant is entered by the user.

[0042] According to an aspect of it, this disclosure provides a cutting machine.

[0043] The cutting machine includes a cutting carousel. The cutting carousel is rotatable about a rotation axis and defines a movement path for plastic caps. The longitudinal axis of the plastic caps is parallel to the rotation axis. The cutting carousel has a plurality of holding devices. The holding devices are angularly arranged on a periphery of the cutting carousel around the rotation axis so as to rotate with the cutting carousel. Each holding device is configured to house a cap and to rotate it so as to bring the plastic cap into contact with a blade of a cutting device.

[0044] The cutting machine comprises a cutting device according to any of the aspects described herein, positioned along the movement path of the cutting carousel.

[0045] According to an aspect of it, this disclosure provides a method for inspecting a cutting device for providing cuts on a surface of a plastic cap. The method comprises a step of providing a blade. The method comprises a step of detecting a vibrational signal representative of a vibration behaviour of the blade. The method comprises a step of receiving the vibrational signal at a control unit. The method comprises a step of processing the vibrational signal to generate vibration data. The method comprises a step of processing the vibration data to generate a blade maintenance signal.

[0046] The method may comprise a step of processing the vibration data to derive a pattern, representative of the vibration behaviour of the blade.

[0047] The method may comprise a step of acquiring the vibration data at a setting instant.

[0048] The method may comprise a step of generating a reference pattern from the vibration data acquired at the setting instant.

[0049] The method may comprise a step of saving the reference pattern.

[0050] The method may comprise a step of acquiring the vibration data at a monitoring instant. The method may comprise a step of generating a monitoring pattern from the vibration data acquired at the monitoring instant.

[0051] The method may comprise a step of comparing the monitoring pattern with the reference pattern.

[0052] The method may comprise a step of estimating a deviation between the reference pattern and the monitoring pattern.

[0053] The method may comprise a step of generating a blade maintenance signal when said deviation exceeds a predetermined threshold.

[0054] The method may comprise a step of periodically updating the monitoring pattern.

[0055] The method may comprise a step of monitoring the working period in which the cutting blade has been used starting from the setting instant. The method may comprise a step of generating the maintenance signal when the working period exceeds a predetermined value.

[0056] In an example, the method comprises a step of providing the blade with a tag. The tag may contain identification information identifying the blade. The method may comprise a step of detecting the blade based on the identification data. The method comprises a step of detecting a replacement of the blade with a new blade and deriving a new reference pattern of the cutting blade when new identification data is detected. The method comprises a step of saving at least one of the following data items to a memory of the tag: a working period in which the cutting blade has been used starting from the setting instant; one or more monitoring patterns of a plurality of monitoring patterns obtained periodically for the cutting blade.

[0057] According to an aspect of it, this disclosure provides a computer program to perform one or more steps of the method described in this disclosure, when run on a processor according to one or more aspects of this disclosure.

[0058] Brief description of drawings

[0059] These and other features will become more apparent from the following description of a preferred embodiment, illustrated by way of non-limiting example in the accompanying drawings, in which:

[0060] - Figure 1 shows a cutting device according to one or more aspects of this disclosure;

[0061] - Figure 2 shows a cutting machine according to one or more aspects of this disclosure.

[0062] Detailed description of preferred embodiments of the invention

[0063] With reference to the accompanying drawings, the numeral 1 denotes a cutting device. The cutting device is mounted in a cutting machine 100 and makes cuts on a surface of a plastic cap T in the cutting machine 100. The cutting machine 100 includes a cutting carousel 101 which rotates about a rotation axis RA and defines a movement path for plastic caps T, as illustrated in Figure 1. In particular, the caps are inserted in holding devices 102 of the carousel 101 which are angularly arranged on a periphery of the cutting carousel around the rotation axis RA so as to rotate with the cutting carousel. The caps are inserted in the holding devices in such a way that a longitudinal axis LA of the plastic caps is parallel to the rotation axis RA. Each holding device houses one cap T and rotates it in the movement path so as to bring the plastic cap into contact with the cutting device which is located laterally of the carousel and tangent to the circumference of the carousel.

[0064] In particular, the cutting machine 100 has an infeed unit which receives the caps to be cut and delivers them to the carousel. The infeed unit may have a conveyor belt. Also, a wheel may be provided to receive the caps from the infeed belt and to carry them to the carousel.

[0065] The cutting machine also includes an outfeed unit O. The outfeed unit comprises a conveyor belt which receives the cut caps from the carousel 102.

[0066] The cutting machine may comprise a device for checking the quality of the cuts, for example, an optical inspection device, downstream of the cutting device.

[0067] The cutting machine may have an actuator to rotate the caps about the longitudinal axis LA so that the caps come into contact with the cutting device at the correct position and angle.

[0068] The cutting machine may include an inspection system for inspecting the angular position of the caps T upstream of and / or at the cutting device 1 .

[0069] The cutting device 1 includes a blade 2. The cutting device includes an upper plate 3A and a lower plate 3B, facing each other and spaced from each other, and the blade 2 is interposed between the upper and lower plates. The blade is stationary at a position outside the carousel. The cutting device includes a plate P which extends horizontally and on which the upper plate 3A and the lower plate 3B are positioned. The cutting device 1 includes a sensor S. In an example, the sensor S is located on the upper plate and preferably at a central position. The upper plate 3A and the lower plate 3B are connected to each other by bolts.

[0070] Alternatively, the blade might be provided with a portion which extends outwards from the plates 3A and 3B so that the sensor is in direct contact with the blade 2.

[0071] The sensor is a vibration sensor.

[0072] The sensor has a frequency of 40-100 kHz, preferably 40 kHz.

[0073] In particular, the sensor S detects a vibrational signal of the blade 2 and the signal is saved and processed by a control unit.

[0074] By processing this signal, the control unit generates a fingerprint (pattern) for the blade. In particular, the vibrational signal is detected at a setting instant. The setting instant may be set by the operator. The fingerprint which is derived from the signal obtained at the setting instant defines the reference fingerprint.

[0075] It should be noted that, in one example, the "pattern" represents a fingerprint of the vibrational behavior of the blade, obtained through specific processing of the acquired vibration data. This processing includes feature extraction from the raw signal, i.e., the identification and selection of significant parameters that effectively summarize the dynamic behavior of the blade.

[0076] Therefore, in this example, the pattern goes beyond a simple comparison of numerical values or raw signals; it provides a structured and detailed representation of the vibrational behavior, which may include, for instance, statistical parameters, characteristic frequencies, modal amplitudes, or other relevant quantities extracted from the signal.

[0077] This processed fingerprint enables a more accurate and robust comparison between the current state of the blade and the reference state stored during the setup phase, thereby facilitating the estimation of potential deviations or anomalies in the vibrational behavior, which in turn allows for the generation of a targeted and timely maintenance signal.

[0078] The setting instant may be before starting a working cycle of the cutting machine or just after the blade is mounted in the cutting device. In particular, the reference fingerprint represents the vibration behaviour of the blade 2 under normal operating conditions, when there are no anomalies.

[0079] In particular, the fingerprint may be derived using feature extraction on the signal from the sensor.

[0080] Next, at a monitoring instant, after the setting instant and during use of the blade 2, another vibrational signal is obtained. This signal is processed and a monitoring fingerprint is derived for the blade at the monitoring instant. The reference fingerprint is compared with the monitoring fingerprint and any deviation greater than a predetermined value indicates a possible blade fault and an alert is generated. The alert may be a prompt to perform maintenance or to replace the blade.

[0081] The reference fingerprint is saved. The monitoring fingerprint may be updated periodically, at predetermined intervals, for example.

[0082] The monitoring fingerprints may be saved. It is also possible to monitor a working period in which the cutting blade has been used starting from the setting instant and to generate the maintenance (alert) signal if the working period exceeds a predetermined value.

[0083] The blade is provided with a tag (RFID tag) 4 containing blade identification information and the blade is identified using the tag. When the blade 2 is replaced, the new blade is recognized by its tag and a new reference fingerprint is derived for the new blade. The tag includes a memory to contain data relating to the cutting blade.

[0084] The data may be a working period in which the cutting blade has been used starting from the setting instant and / or one of more monitoring patterns of a plurality of monitoring fingerprints obtained periodically for the cutting blade.

[0085] When a maintenance service is performed on the blade, an additional reference fingerprint is derived for the blade.

[0086] The tag therefore allows the blade to be recognized automatically and unambiguously identified so as to automate working hour monitoring operations and to start a new step of deriving the reference fingerprint, if the blade 2 is replaced.

[0087] The cutting device 1 also includes an RFID reader 5 located on the plate in communication with the tag.

Claims

CLAIMS1. A cutting device (1 ) for providing cuts on a surface of a plastic cap (T) in a cutting machine (100), the cutting device comprising:- a blade (2);- a sensor (S) configured for detecting a vibrational signal representative of a vibration behaviour of the blade;- a control unit, having a memory and a processor, connected to the sensor to receive the vibrational signal and programmed to process the vibrational signal to generate vibration data, and to process the vibration data to generate a blade maintenance signal.

2. The cutting device (1 ) of claim 1 , wherein the control unit is programmed to process the vibration data to derive a pattern, representative of the vibration behaviour of the blade, the control unit being operable in a setup configuration and in a monitoring configuration, wherein, in the setup configuration, the control unit is programmed to save, as a reference pattern, the pattern generated from the vibration data acquired at a setting instant, and in the monitoring configuration, the control unit is programmed to compare a pattern generated from the vibration data acquired at a monitoring instant with the reference pattern, to estimate a deviation between the reference pattern and the monitoring pattern, and wherein the control unit is programmed to generate the blade maintenance signal as a function of said deviation.

3. The cutting device (1 ) according to claim 2, wherein the control unit is programmed for periodically updating the pattern generated from the vibration data acquired at the monitoring instant.

4. The cutting device (1 ) according to claim 2 or 3, wherein the control unit is programmed to derive the pattern by performing feature extraction on the vibration signal.

5. The cutting device (1 ) according to any of the previous claims, whereinthe control unit is configured to monitor a working period in which the cutting blade has been used starting from the setting instant and to generate the maintenance signal if the working period exceeds a predetermined value.

6. The cutting device (1 ) according to any of the previous claims, wherein the blade is provided with a tag containing identification information identifying the blade and the control unit is configured for detecting the blade based on the identification data.

7. The cutting device (1 ) according to claim 6, wherein the control unit is configured to detect a replacement of the blade responsive to detection of new identification information, and to derive a new reference pattern upon detection of the replacement.

8. The cutting device (1 ) according to claim 6 or 7, wherein the control unit is configured to derive an additional reference pattern upon detection of a maintenance service performed on the cutting blade representative of the vibration behaviour of the blade post maintenance.

9. The cutting device (1 ) according to any of the previous claims from 6 to 8, wherein the tag is provided with a memory to contain data relating to the cutting blade.

10. The cutting device (1 ) according to claim 9, wherein the data includes at least one of the following:- a working period in which the cutting blade has been used starting from the setting instant;- one or more monitoring patterns of a plurality of monitoring patterns obtained periodically for the cutting blade.

11. The cutting device (1 ) according to any of the previous claims, wherein the sensor has a frequency of 40-100 kHz.

12. The cutting device (1 ) according to any of the previous claims, wherein the cutting device includes an upper plate (3A) and a lower plate (3B), facing each other and spaced from each other, wherein the cutting blade (2) is interposed between the upper and lower plates, wherein the sensor(S) is placed on the upper plate.

13. The cutting device (1 ) according to any of the previous claims, wherein the control unit is configured to generate an alert in response to the generation of the maintenance signal.

14. The cutting device (1 ) according to any of the previous claims wherein the setting instant is entered by the user.

15. A cutting machine (100) comprising:- a cutting carouse 101 , rotatable about a rotation axis (RA) and defining a movement path for plastic caps (T), wherein a longitudinal axis (LA) of the plastic caps is parallel to the rotation axis (RA), wherein the cutting carousel has a plurality of holding devices (102), angularly arranged on a periphery of the cutting carousel around the rotation axis so as to rotate with the cutting carousel, wherein each holding device (102) is configured to house a cap and rotate it so as to bring the plastic cap into contact with a blade (2) of a cutting device (1 );- the cutting device (1 ) according to any of the previous claims, placed along the movement path of the cutting carousel.

16. A method for inspecting a cutting device for providing cuts on a surface of a plastic cap (T) comprising the following steps:- providing a blade (2);- detecting a vibrational signal representative of a vibration behaviour of the blade;- receiving the vibrational signal at a control unit;- processing the vibrational signal to generate vibration data, and processing the vibration data to generate a blade maintenance signal.

17. The method according to claim 16, comprising the following steps:- processing the vibration data to derive a pattern, representative of the vibration behaviour of the blade;- acquiring the vibration data at a setting instant;- generating a reference pattern from the vibration data acquired at the setting instant;- saving the reference pattern;- acquiring the vibration data at a monitoring instant;- generating a monitoring pattern from the vibration data acquired at the monitoring instant;- comparing the monitoring pattern with the reference pattern;- estimating a deviation between the reference pattern and the monitoring pattern;- generating a blade maintenance signal, when said deviation exceeds a predetermined threshold.

18. The method according to claim 17, comprising a step of periodically updating the monitoring pattern.

19. The method according to any of claims 16-18, comprising a step of monitoring a working period in which the cutting blade has been used starting from the setting instant and generating the maintenance signal when the working period exceeds a predetermined value.

20. The method according to any of the previous claims from 16 to 19, comprising the following steps:- providing the blade with a tag containing identification information identifying the blade;- detecting the blade based on the identification data;- detecting a replacement of the blade with a new blade and deriving a new reference pattern of the cutting blade when new identification data is detected;- saving at least one of the following data items to a memory of the tag: a working period in which the cutting blade has been used starting from the setting instant; one or more monitoring patterns of a plurality of monitoring patterns obtained periodically for the cutting blade.

21. A computer program for carrying out the steps of any of the claims 16 to 20 when run on the processor of claim 1 .

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