Capping head for pre-threaded caps with detection of attainment of maximum torque

Abstract

Capping head (1) for applying pre-threaded caps to containers, said capping head using a coupling device (11, 12) to control the applied torque and comprising means (13a, 13b, 15) for detecting the intervention of the coupling device (11, 12), which means comprise at least one magnet (13a; 13b) integral in rotation with an element (11) of the coupling device integral in rotation with a cap-handling member (4) and a magnetic field sensor (15) integral in rotation with an element (12) of the coupling device integral in rotation with a rototranslating driving member (3). The sensor (15) uses bistable magnetic components, detecting changes of state of these components at each passage of the magnet or a magnet (13 a; 13b) opposite the sensor (15) when a relative rotation between said rotating elements of the coupling device takes place following intervention of said coupling device.

Description

[0001] “Capping head for pre-threaded caps with detection of attainment of maximum torque ”

[0002] DESCRIPTION

[0003] Technical Field

[0004] The present invention relates to capping plants, and more particularly it concerns a capping head for applying pre-threaded caps (or screw caps, these two term being used interchangeably) to containers, with detection of attainment of the maximum torque applied to the caps.

[0005] The invention further relates to a capping machine and a capping method using such head. Background Art

[0006] During operations of capping containers, it is usual to monitor the values of certain parameters characterizing the operation. In particular, in the case of capping by using screw caps, one of these parameters is the torque applied to the cap. The monitoring makes it possible, in particular, to ascertain when a predetermined maximum torque (corresponding generally to the condition of full screwing of the cap) is attained, so as to interrupt operation in order not to exceed the maximum torque.

[0007] To control the torque, in conventional capping heads it is usual to introduce, between a caphandling member (cone-shaped cap chuck) and a driving member (in particular, a rototranslating shaft), a coupling device, usually of the clutch-type, for example, with a magnetic clutch, which decouples the cap-handling member from the driving member and stops it upon attainment of the maximum torque. An example of a head with magnetic clutch is disclosed in EP 2407415 Al in the name of the Applicant.

[0008] The problem with these known heads lies in that they do not provide information on the actual intervention of the clutch, i.e., they do not allow detecting whether, and for how long, one of the clutch parts has actually stopped because the predetermined maximum torque has been attained.

[0009] A capping device for pre-threaded caps is known from WO 2018 / 142290 Al, having a magnetic clutch coupling device comprising a pair of coaxial rotors, one of which carries a number of magnets, and the other one is made of a material with magnetic hysteresis or also carries a number of magnets. The coupling device is associated with magnetic force sensors to detect the relative position of the two rotors in the axial and / or circumferential direction, which sensors are adapted to wirelessly transmit the detected data to a control member. Powering of the detection means can also be effected wirelessly. The sensors, the data processing device and the transmitter are arranged on the same rotor of the clutch, together with the means for powering them. This arrangement may increase the inertia of the head, because the components of the detection means, however miniaturized they may be, still have a certain overall mass. As is apparent to the skilled person, the increase in inertia due to an inappropriate arrangement of the components of the detection means, in turn, negatively affects the actual capping stage and may cause deterioration in the performance of the head. This effect is enhanced by the presence, on the same rotor, of the powering means for these components.

[0010] The object of the present invention is to provide a capping head for applying pre-threaded caps to containers that solves the problems of prior art.

[0011] Summary of Invention

[0012] The object is achieved with a capping head in which there are provided a coupling device to control the torque applied to a cap and decouple a cap-handling member from a driving member when the torque applied to a cap exceeds a maximum torque, and detection means for detecting intervention of the coupling device. These detection means comprise at least one magnet and a magnetic field sensor that are integral in rotation with rotating elements of the coupling device, which rotating elements in turn are integral in rotation with a cap-handling member and a rototranslating driving member. The sensor includes bistable magnetic components and is arranged to detect the changes of state of said bistable magnetic components occurring whenever the at least one magnet passes opposite the sensor when a relative rotation between said rotating elements of the coupling device takes place following the decoupling of the cap-handling member from the driving member caused by the intervention of the coupling device.

[0013] Preferably, the magnetic field sensor is a sensor based on the Wiegand effect, which generates an electric pulse at each change of state of said bistable magnetic components.

[0014] The detection means may include a single multipole magnet in which the magnetic field variation takes place at the surface, in which case the sensor is horizontally arranged, or a plurality of magnets with vertical magnetic fields arranged with alternate polarities, in which case the sensor is vertically arranged.

[0015] Preferably, the detection means further comprise means intended for processing the signals generated by the sensor and housed in a casing arranged externally to a casing for the coupling device, the latter casing being integral in rotation with the driving member.

[0016] Advantageously, the casing for the processing means is made of an electrically nonshielding material in order to allow the processed signals to be transmitted to a control system wirelessly, more particularly with radio frequency, and the processing means to be powered wirelessly, more particularly with radio frequency, by an external power source.

[0017] Advantageously, the casing for the processing means is secured to the top of the casing for the coupling device and is made integral in rotation with the latter by means of an anti-rotation ferrule.

[0018] The invention further provides a capping machine comprising one or more capping head(s) as described above, and a control system arranged to receive signals supplied by the detecting means and to analyze such signals in order to detect the proper or wrong intervention or the non-intervention of the coupling device.

[0019] According to a further aspect, the invention provides a method of capping containers by means of pre-threaded caps, said method being implemented by capping heads as described above, wherein the intervention of the coupling device is detected by means of the following steps: applying at least one magnet to a first rotating element of the coupling device, integral in rotation with the cap-handling member; applying a magnetic field sensor including bistable magnetic components to a second rotating element of the coupling device, integral in rotation with the driving member; by means of the magnetic field sensor, detecting the changes of state of said bistable magnetic components occurring at the passage of the at least one magnet opposite the sensor when a relative rotation between the rotating elements takes place following the intervention of the coupling device, and generating an electric pulse at each detected change of state; counting the generated pulses in order to detect the relative position of the rotating elements and storing the counts of said pulses; and processing the electric pulses generated by the sensor, transmitting the processed signals to a control system and analyzing such signals in order to detect the proper or wrong intervention or the non-intervention of the coupling device.

[0020] Brief Description of Drawings

[0021] These and other features and advantages of the present invention will become evident from the following description of preferred embodiments given by way of non-limiting example with reference to the annexed drawings, in which:

[0022] Fig.l is an isometric view of a turret capping machine equipped with capping heads according to the invention;

[0023] Fig.2 is an isometric view of a capping head according to the invention;

[0024] Fig.3 is an exploded view of the capping head of Fig. 2; Fig.4 is an enlarged view of a detail of the capping head of Figs. 2 and 3;

[0025] Fig.5 is a view in axial section of a capping head according to the invention using a

[0026] Wiegand effect sensor activated by a single magnet for detecting the intervention of a coupling device with magnetic clutch;

[0027] Fig.6 is a view in axial section of a capping head according to the invention using a Wiegand effect sensor activated by a plurality of magnets for detecting the intervention of a coupling device with magnetic clutch; and

[0028] Fig.7 shows a possible assembly of the electronic components of a device for detecting the intervention of the coupling device.

[0029] Description of Embodiments

[0030] Referring to Figures 1 - 4, these schematically show a rotary capping machine (or turret) 100 equipped with a plurality of capping heads 1 according to the invention for applying screw caps to containers such as bottles, containers, etc.

[0031] The heads 1 are carried by a platform 101 integral with a vertical axis shaft 102 which is rotated about its own axis to bring a head 1 to a container to be capped (not shown in the drawings), bring the containers and the heads to a capping position and then bring the containers, once capped, to a position in which they are taken out of the capping machine 100. The caps are fed to the heads 1 by a conventional cap transfer disc 103 which picks them up from a distribution channel, not shown.

[0032] Each capping head 1 comprises a body 2 attached to a rototranslating driving shaft 3 extending coaxially inside the body 2, said body housing the members that transmit the movements necessary for capping to a cap-handling member or cone-shaped cap chuck 4. In particular, in the body 2 there are arranged a coupling device, interposed between the shaft 3 and the cone-shaped cap chuck 4 to control the torque transferable by the shaft 3 to the cone- shaped cap chuck 4 during capping and causing the cone-shaped cap chuck 4 to stop when a pre-set maximum torque is attained, and elastic elements for applying the compensating axial load (top load).

[0033] By way of example only, here below reference will be made to a coupling device consisting of a magnetic clutch, shown in Figures 5 and 6. The coupling may, however, also comprise generically a pair of rotating elements integral in rotation with the rototranslating driving shaft 3 and the cone-shaped cap chuck 4, respectively. In the description below, the two elements of the coupling device will also be referred to as rotors.

[0034] In the shown case of a magnetic clutch, this can be of the type with synchronous magnets or with magnetic hysteresis. The type of clutch has no influence on the invention.

[0035] The shaft 3 has its axis parallel to the rotation axis 102 of the turret 100 and is driven in rotation for example by a gear system or an electric motor. The rotation-controlling members are arranged inside a body 104 of the turret 100 which also houses the members controlling the vertical translation of the shaft 3, for example, a system with mechanical cam and cam follower rollers, or an electric motor. The members controlling rotational and translational movements are entirely conventional and therefore will not be described further. For more details about this structure, reference is made, for example, to the already cited document EP 2407415 Al.

[0036] The body 2 of the head 1 is secured to the shaft 3 by means of an anti-rotation ferrule 5 coaxially received in a second ferrule 6 attached to the upper part of the body 2 of the head 1 and also integral in rotation with the shaft 3. This ferrule is intended to receive the electronic components, to be described below, of a device for detecting intervention of the clutch, and is made of an electrically non-shielding material.

[0037] A USB port 7, which can be closed with a cover 8, is provided on the ferrule 6, the functions of said USB port being explained below when describing the electronic components of the device for detecting intervention of the clutch.

[0038] Referring to Figures 5 and 6, these show, respectively, a capping head 1 and a part of the body 2 thereof in an embodiment example in which the magnetic clutch is of the type with synchronous magnets and consists of two vertical-axis magnetic discs 11, 12 arranged facing each other. The disc 11 is integral with the cone-shaped cap chuck 4, whereas the disc 12 is integral with an element permanently driven by the rotational motion imparted by the shaft 3. As is clear to the skilled person, the two discs of the clutch rotate synchronously with each other until the time when the resistant torque applied to the disc 11 exceeds the magnetic torque exerted on each other by the two magnetic discs, which can occur as a result of the progressive engagement between the thread of the cap and the thread of the container, or in case of malfunction of the capping head. The disc 11 will then stop when the pre-set maximum torque, defined by the distance between the two discs 11, 12, is attained.

[0039] If the clutch is of the hysteresis type, it will comprise coaxial magnetic rings instead of parallel discs.

[0040] The clutch is associated with a device for detecting intervention of the clutch resulting in loss of synchronism between the two rotors 11, 12. This detection device is a magnetic device using bistable magnetic components in which the magnetic field is periodically reversed, in particular a detection device that exploits the Wiegand effect. The detection device comprises a bistable magnet 13a (Fig. 5) or a plurality of bistable magnets 13b (Fig. 6), for example six, which is / are carried by a support 14 integral in rotation with the rotor 11 integral with the cone-shaped cap chuck 4, and therefore stops together therewith upon intervention of the clutch, and a sensor 15, which consists of bistable magnetic elements, in particular Wiegand wires, and is carried by a support 16 integral in rotation with the rotor 12 permanently rotating with the shaft 3.

[0041] The operating principles of a device for detecting rotation of an object based on the Wiegand effect are described in more detail for example in document https: / / www.yourelectricalguide.com / 2022 / 03 / wiegand-sensor-working-principle- applications.html, which can be found on the Internet site https: / / www.yourelectricalguide.com.

[0042] Wiegand sensors are devices commonly available on the market.

[0043] In the case of a single magnet 13a, this is a multipole magnet in which the magnetic field variation takes place at the surface, and thus, in order to detect such variation, the sensor 15 needs to be arranged horizontally, as can be seen in Figure 5.

[0044] In the case of a plurality of magnets 13b, these are bipolar magnets with vertical magnetic fields and are arranged with alternate polarities on the support 14. In this case, to detect the inversion of polarity, the sensor is arranged vertically, as can be seen in Figure 6.

[0045] The solution with several magnets 13b and vertical sensor 15 is preferable because a limited number of bipolar magnets like the one taken as an example is less expensive than a single multipole magnet. Furthermore, bipolar magnets are more easily available on the market.

[0046] Associating only the magnet 13a or the magnets 13b with the rotor 11 integral with the cone-shaped cap chuck 4 causes minimal additional inertia to be introduced into the system, which, moreover, is itself designed to exhibit limited inertia even in the absence of the detection device according to the invention, with the ultimate goal of affecting as little as possible the actual capping operation performed by the cone-shaped cap chuck.

[0047] When loss of synchronism between the two rotors 11, 12 of the magnetic clutch occurs, the sensor 15 generates, in a known manner, electric pulses representative of the inversion of the magnetic field of the clutch components each time a magnetic dipole of the single magnet 13a or one of the magnets 13b passes opposite the magnetic field. The sensor 15 then detects the position in which an inversion of magnetic field has occurred, and therefore the relative position of the two rotors 11, 12. In addition, thanks to the generation of electric pulses, the sensor 15 also acts as power generator, i.e. the pulses make it possible to electrically feed an electronic system which detects and permanently stores (in a non-volatile memory) the actuation thereof. The pulses are sent via a cable 17 to the electronic processing components arranged in the ferrule 6, and the processed signals are then transmitted to a receiver that is part of a system for controlling the capping machine 100 in which the capping head 1 is used. The receiver will analyze the received signals to recognize, also on the basis of the information obtained with the usual general monitoring of the operations of the capping machine, the correct or incorrect intervention, or the non-intervention, of the clutch.

[0048] The number of magnetic dipoles on the single magnet 13a or the number of magnets 13b in the case of several magnets determines the number of magnetic field inversions occurring at each revolution of the rotor 11 and therefore the number of pulses generated by the sensor 15 and the resolution of the detection device.

[0049] Advantageously, the transmission of the processed signals to the receiver takes place in a wireless mode. As is clear to the skilled person, the use of wireless technology for the transmission of data by the detection device is the preferred solution, taking into account that said device is mounted to a mobile structure and therefore the data transmission cables might hinder the movements of said structure or be damaged by such movements. For the same reasons, it is also advantageous using a wireless technology for feeding the components of the device.

[0050] Referring now to Figure 7, the electronic components of the detection device are mounted in a conventional manner on a printed circuit board 20 arranged in the ferrule 6. In principle, they will include: a module 24 for acquiring the signal from the sensor 15; a data transmission antenna 22; a data transmission module; a power adjustment module; a data storage module; a battery or power supply means receiving power provided in a wireless manner, for example, by means of radiofrequency technology, by an external source.

[0051] In particular, a central processing unit (CPU) or microcontroller 21 can be seen in Figure 7, with which the antenna 22 for transmitting the processed signals to the control system is associated. In order to power the components, the figure illustrates a battery 23, which advantageously is a rechargeable battery. If the components are powered by means of power provided in wireless mode by the external source, an antenna for receiving such power will be provided in place of the battery 23. The signals coming from the sensor 15 through the cable 17 arrive at the module 24 for acquiring the sensor signal. For the sake of accuracy, it is noted that the figure actually shows the housings in which the battery 23 and module 24 are accommodated, rather than the components themselves.

[0052] The acquisition module 24 will comprise, among other things, a counter for counting the pulses generated by the sensor 15 and a non-volatile memory, advantageously of the FRAM (Ferromagnetic RAM) type, for storing the count results. These elements, as mentioned, are powered by the pulses generated by the sensor. A start button 25 and state LEDs 26 are also provided. The USB port 27 is used to connect a cable for updating the firmware of the central processing unit 21 and for serial debugging. In the case of battery supply, the same port is also used to recharge the battery through an appropriate mains adapter.

[0053] The data transmission module, power adjustment module and data storage module are not indicated explicitly as they are assumed to be included in the CPU 21.

[0054] It should be noted that arranging the electronic components of the detection device in the ferrule 6, made of an electrically non-shielding material and located outside the metal body 2 of the head, causes the data transmission antenna 22 and the power receiving antenna, if any, to be unshielded, rather than being shielded as would instead occur if said components were arranged inside the body 2. Therefore, the management of data transmission and possible power reception is significantly smoother.

[0055] The described capping head effectively solves the problems of prior art.

[0056] Having only the magnet or magnets on the rotating element integral with the cone-shaped cap chuck 4 minimizes, as mentioned, any additional inertia and thus reduces or prevents the problems outlined above.

[0057] In addition, the Wiegand effect sensor, acting also as generator, eliminates the need for an additional power supply for such sensor and the non-volatile memory in which the detection results are stored. This also contributes to solve the problem of inertia.

[0058] It is apparent that the above description has been given merely by way of example and that numerous variations and modifications are possible without leaving the scope of protection as defined by the appended claims. In particular, even if a coupling device with magnetic clutch between the rototranslating shaft 3 and the cone-shaped cap chuck 4 has been illustrated, the coupling device may also, as mentioned, be of a different type, provided that it comprises two rotating elements to which the magnet 13a or the magnets 13b and the Wiegand effect sensor 15, respectively, are integrally attached.

Claims

CLAIMS1. Capping head (1) for applying pre-threaded caps to containers, including:- a coupling device (11, 12) arranged to decouple a cap-handling member (4) from a driving member (3) when a resistant torque applied to a cap exceeds a torque mutually exerted between a pair of rotating elements (11, 12) of the coupling device, integral in rotation with a respective one of said members (4, 3);- means (13a, 13b, 15) for detecting the intervention of the coupling device (11, 12), including at least one magnet (13a, 13b) and a magnetic field sensor (15) that are associated with said rotating elements (11, 12) so as to be integral in rotation therewith, characterized in that the magnetic field sensor (15) includes bistable magnetic components and is arranged to detect the changes of state of said bistable magnetic components occurring whenever the at least one magnet (13a; 13b) passes opposite the sensor (15) when a relative rotation between said rotating elements (11, 12) of the coupling device takes place following the decoupling of the cap-handling member (4) from the driving member (3) caused by the intervention of the coupling device (11, 12).

2. Capping head (1) according to claim 1, wherein the magnetic field sensor (15) is a sensor based on the Wiegand effect and generates an electric pulse at each change of state of said bistable magnetic components.

3. Capping head (1) according to claim 1 or 2, wherein the at least one magnet (13a; 13b) is associated with the element (11) of the coupling device (11, 12) integral in rotation with the cap-handling member (4) and the magnetic field sensor (15) is associated with the element (12) of the coupling device (11, 12) integral in rotation with the driving member (3).

4. Capping head (1) according to any of the preceding claims, wherein the means (13a, 13b, 15) for detecting the intervention of the coupling device (11, 12) include a single multipole magnet (13a) in which the magnetic field variation takes place at the surface, and the sensor (15) is horizontally arranged.

5. Capping head (1) according to any of claims 1 to 3, wherein the means (13a, 13b, 15) for detecting the intervention of the coupling device (11, 12) include a plurality of magnets (13b) with vertical magnetic fields arranged with alternate polarities, and the sensor (15) is vertically arranged.

6. Capping head (1) according to any preceding claim, wherein:- the means (13a, 13b, 15) for detecting the intervention of the coupling device (11, 12) further include means (20, 21, 22, 23) for processing the signals generated bythe sensor (15) because of the changes of state of the bistable magnetic components, and said processing means are housed in a casing (6) arranged externally to a casing(2) for the coupling device (11, 12), integral in rotation with the driving member(3); and- the casing (6) for the processing means (20, 21, 22, 23) is secured through an antirotation ferrule (5) to the top of the casing (2) for the coupling device (11, 12) so as to be integral in rotation with the latter casing.

7. Capping head (1) according to claim 6, wherein the casing (6) for the processing means (20, 21, 22, 23) is made of an electrically non-shielding material.

8. Capping head (1) according to claim 7, wherein:- the processing means (20, 21, 22, 23) are arranged to transmit the processed signals to a control system in wireless mode; and- the processing means (20, 21, 22, 23) are powered either by a battery (23) housed within the casing (6) for the processing means (20, 21, 22, 23) or by the power that is supplied in wireless mode by a source external to a capping machine to which the head belongs and is received by an antenna located in said casing (6) for the processing means (20, 21, 22, 23) in place of the battery (23).

9. Capping machine (100) for applying pre-threaded caps to containers, comprising: one or more capping heads (1) equipped with means (13a, 13b, 15) for detecting the intervention of a coupling device (11, 12) arranged to decouple a cap-handling member (4) from a rototranslating driving member (3) upon attainment of a predetermined maximum torque, according to any preceding claim; and a control system arranged to receive signals supplied by the detecting means (13a, 13b, 15) and to analyze such signals in order to detect the correct or incorrect intervention, or the non-intervention, of the clutch (11, 12).

10. Capping method for applying pre-threaded caps to containers by means of a capping head (1) providing for the detection of the intervention of a coupling device (11, 12) arranged to decouple a cap-handling member (4) from a rototranslating driving member (3) upon attainment of a predetermined maximum torque, wherein the detection of the intervention of the coupling device (11, 12) includes the steps of: applying at least one magnet (13a, 13b) to a first rotating element (11) of the coupling device, integral in rotation with the cap-handling member (4); applying a magnetic field sensor (15) including bistable magnetic components to asecond rotating element (12) of the coupling device integral in rotation with the driving member (3); by means of the magnetic field sensor (15), detecting the changes of state of said bistable magnetic components occurring at the passage of the at least one magnet (13a; 13b) opposite the sensor (15) when a relative rotation between said rotating elements (11, 12) takes place following the intervention of the coupling device (11, 12), and generating an electric pulse at each change of state; counting the generated pulses in order to detect the relative position of the rotating elements (11, 12) and storing the counts of said pulses; and processing the electric pulses generated by the sensor (15), transmitting the processed signals to a control system and analyzing such signals in order to detect the correct or incorrect intervention, or the non-intervention, of the clutch (11, 12).

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