Electropermanent magnetic system

Abstract

An electropermanent magnetic system (10) comprising an electropermanent magnet module (12) and an electronic control panel (11) configured to supply an electric current to the electropermanent magnet module (12) in order to magnetize or demagnetize it, as well as an electrical connection (13) between the control panel (11) and the electropermanent magnet module (12), wherein the electropermanent magnet module (12) comprises a permanently connected magnetization indicator (14), characterized in that the magnetization indicator (14) comprises an e-paper screen (EP) configured to display, in a first zone (Z1), at least one item of information relating to the magnetization state of the electropermanent magnet module (12), even when the e-paper screen (EP) is not activated.

Description

TECHNICAL FIELDThe present invention relates to an electropermanent magnetic system.In particular, it is an electropermanent magnetic system equipped with a magnetic state indicator.PRIOR ARTElectropermanent magnetic systems are magnetomechanical devices that serve to anchor ferromagnetic material. The peculiarity of these devices is that they can be activated (i.e. magnetized) by a suitable supply of electric energy and deactivated (i.e. demagnetized) by a likewise suitable supply of energy.Typical of the system is that the energy is delivered via an electrical control unit and is limited in time; it is normally limited to a few seconds.As a result, they are energy-saving and above all the electrical control system does not have to be permanently connected to the anchoring device.If, therefore, electropermanent anchoring devices are mounted on the table of a machine tool (e.g. a lathe, a milling machine, etc.), it is possible to equip them with plug connectors with which they can be connected only if required and activated or deactivated at the beginning or at the end of the mechanical machining.In this way, the need to make permanent wiring on the working surface of the machine itself is avoided, which is always a complex operation due to the environment particularly unfavourable for electric cables (presence of hot chips, lubricants, water, oils etc.).Moreover, electropermanent systems allow the "off-line" loading of materials to be processed on multi-pallet systems in the same way as screwing poles, so that no loading times are incurred, which is certainly not possible with electromagnets. In contrast to screw heads, however, they do not require a geometric handle and leave five of six surfaces of the object to be machined free (and thus accessible for machining).As described, electropermanent systems require energy only for "turn-on" or "turn-off" (i.e., in the magnetization or demagnetization process), with the particularity that the power may be particularly intense with respect to the energy delivered.In order to avoid very high power output, manufacturers of magnetic systems can subdivide them into subsections which are activated successively. In this way, the same power is supplied, which extends time and reduces electric power.In other cases, the partitioning of surface activation of an electropermanent system may be a feature that requires the application for which it is to be used for various reasons. In particular, it is possible to obtain anchoring systems of variable configuration, in which the whole anchoring surface S is divided as follows: where S 1, S 2, S 3, S 4 are surfaces which can be activated independently of each other.In general, the electrical control device of the magnetic anchoring system, also referred to as a control unit, not only activates the surface(s) of which the magnetic plane is (are) formed, but also checks their correct activation or deactivation by notifying the general user (human or machine) of the magnetic state of the system.In essence, the electropermanent system is characterized by its magnetic states, which we list and describe for simplicity.Demagnetization: The magnetic system has a neutral surface on which no (magnetic) force field is built up. The system remains in this state indefinitely when in its intended operating state without requiring energy to remain in this state.Magnetized: The magnetic system has a magnetically active surface and is surrounded by a (magnetic) force field. The system remains in this state indefinitely when it is in the operating conditions provided by the device itself, without requiring energy to remain in this state.Transition from magnetization to demagnetization; the magnetic system has a surface that gradually becomes neutral with the relative cancellation of the force field thereon. The system remains in this state for a certain and limited time. This transition requires the supply of electrical energy by the electrical control device to which the magnetic system must be connected.Transition from demagnetized to magnetized; the magnetic system has a surface on which a force field gradually builds up. The system remains in this state for a certain and limited time. This transition requires the supply of electrical energy by the electrical control device to which the magnetic system must be connected.As can easily be seen, there must be an electrical connection between the magnetic device and the control unit in the two transition states, since the electrical energy must be supplied by the electrical control unit. This connection can be canceled when one of the two stable states is reached.In an electropermanent system it is also possible to modulate the anchoring force by varying the electrical power with which it is activated.In the control of electropermanent anchoring systems, a single controller is often used to activate multiple magnet systems or sub-regions.In such a case, the information transmitted by the control unit could be completely incompatible with the magnetic state of the anchoring systems in the relevant environment.Another common case when using such systems is the presence of multiple control units and multiple magnetic systems.As long as the controller is connected to the magnetic plane, there is certainty that the information about the magnetic state of the plane coincides with that of the corresponding controller, but once the connection is disconnected, this certainty is lost.This has caused various manufacturers of magnetic systems to develop devices that indicate the magnetic state of the system on the system. In particular, EP2742363 A1 describes, in the name of the same applicant, a bistable electromechanical device which is rigidly connected to the anchoring system in order to indicate its magnetic state.This indicator is actuated by the control unit of the magnetic system, which activates or deactivates the magnetic surface of the anchoring device.It rotates the motor inside the state indicator via a communication channel to indicate a colored area indicating the state of the electropermanent magnet.As a result, the information about the (de)magnetization is transmitted from the control unit to the "magnetic system".The bistable device described in patent EP2742363 A1 has the characteristic that it does not require energy to remain in the desired specific display state, which is extremely important for all systems in which the connection is detachable.The user can recognize the magnetization state of the magnetic system with a view of the indicator.Since the indicator does not require power (e.g., a battery) to indicate its state, it will constantly indicate the system magnetization state even though the cabling to the controller is disconnected and even though a great deal of time has elapsed since the last magnetization / demagnetizationAn indicator such as that described above has the disadvantage that it can only transmit a single binary indication to the user.SUMMARY OF THE INVENTIONThe object of the present invention is to develop a magnetic system which is an improvement over the known technique.It is advantageous that the magnetic system provides more information to the user than is the case with known systems.These and other purposes are achieved by a magnetic system in accordance with the technical teachings of the appended claims.BRIEF DESCRIPTION OF THE FIGURESFurther features and advantages of the invention will become apparent from the description of a preferred, but not exclusive embodiment of the device, which is illustrated by way of example and therefore not by way of limitation in the appended figures, and in which FIG. 1 is a perspective view of an electropermanent magnetic system according to the present invention; FIG. 2 is a partially simplified perspective view of a portion of the magnetic system in FIG. 2. 1 FIG. 2A is a detail view, partly in section, of a pole of the part shown in FIG. 2; FIG. 3 is an enlarged and more detailed exploded view of a portion of FIG. 2 ; FIG. 4 is a detailed view of a portion of the screen of a magnetization indicator of the present invention; and FIG. 5 is a block diagram illustrating the logical / physical components of the magnetic system.DETAILED DESCRIPTION OF THE INVENTIONReferring to the figures, an electropermanent magnetic system is shown at 10.The electropermanent magnetic system 10 includes an electropermanent magnet module 12 and an electronic control panel 11 configured to supply an electric current to the electropermanent magnet module 12 to magnetizing or demagnetize it.The electropermanent magnet module 12 may be an electropermanent magnet surface. However, it may have another configuration, for example, a magnetic lifting system, a magnetic system attached to the wrist of a robot for pick & place applications, etc.It is configured to fix a ferromagnetic workpiece, for example, in any type of mechanical processing by utilizing a magnetic anchoring force generated by the electropermanent magnet module 12.The electropermanent magnet module 12 can also be used to secure ferromagnetic workpieces during transport. In this case, the electropermanent magnetic module is connected to a handling element (e.g. a crane).The electropermanent magnet module 12 may comprise a plurality of ferromagnetic poles 120 (FIG. 2A ) connected to non-reversible magnets 300, preferably neodymium, and to reversible magnets 301, preferably AlNiCo; each reversible magnet 301 may be associated with at least one reversing coil 302 connected to the control panel 11 at least for its supply of current.The operation of the electropermanent magnet module 12 and its industrial applications are well known and will not be described further herein.As shown in FIG. 1, there is an electrical terminal 13 between the control panel 11 and the electropermanent magnet module 12.The electrical connection system may provide connectors C connected to the electropermanent magnetic module 12 and the control panel 11 and to which an electrical cable is connected. In this case, the electrical terminal 13 is detachable.The electrical connection 13 comprises the wiring for magnetizing the electropermanent magnet module 12, i.e. for exciting the reversing coils, and optionally the wiring of a data bus, the use of which will be clarified later.As shown in FIG. 2, more preferably FIG. 3, the electropermanent magnet module 12 includes a permanently associated magnetization indicator 14.In this text, the term "fixedly connected" means that the magnetization indicator 14 cannot be separated from the electropermanent magnet module 12 (or simply module 12) in normal use. It is therefore integrated into the module 12.Thus, the magnetization indicator 14 is always visible at least from certain angles when looking at the module 12.According to the invention, the magnetization indicator 14 comprises an e-paper screen EP.As shown in FIG. 3, the e-paper screen EP may be part of the indicator 14. The indicator 14 consisting of the printed circuit board and the screen EP can be accommodated, for example, in a cassette 201 which is surrounded by a transparent protective screen 202. The cartridge 201 (and hence the indicator 14) is housed in a recess 51 formed in the frame 50 of the module 12.A seal 200 may be provided between the cartridge 201 and the recess 51.It should be noted that in FIG. 3, the electrical connections between the indicator 14 and the connector C or other elements of the module 12 (whatever is present) are not shown.The e-paper screen EP is configured to display at least one item of information about the magnetization state of the module 12 in a first zone Z 1, even if the e-paper screen is de-energized.The information about the magnetization state may be, for example, a label (as in the case shown in FIG. 3 or FIG. 4 ) or a symbol or logo that is or can be connected to the magnetization state of the module 12.The electropermanent magnetic module 12 may have, for example, various magnetic states.For example, it can be magnetized over the full surface at maximum power; in this case, the label MAG ON can appear on the screen.Moreover, it may be magnetized 25% over the entire area, so that the label MAG 25% can be displayed.Here too, it can be demagnetised, in which case the label MAG OFF can appear on the screen.Of course, module 12 may also have other magnetic states (e.g., only certain poles 120 may be magnetized).And for each "magnetic state", the screen may display a label or icon that preferably uniquely indicates the magnetic state of the electropermanent magnetic module 12.Advantageously, the information about the state of magnetization (and thus what is written to the e-paper screen) may comprise at least the following three states: a state of magnetization (completely or partially), a state of demagnetization and a state of failure.The fault condition, which is of fundamental importance, is "written" to the E-paper if there is any type of deviation or a fault is detected during magnetization or demagnetization or during any phase of the operation of the surface.Typical and visible fault conditions may result from a wrong current flow in the coils, which means poor magnetization or demagnetization.Likewise, partial damage to the coils may mean partial magnetization of the system, which may be indicated. The latter case is particularly important because a magnet is not fully active, i.e. does not have the full expected force, but is also not fully inactive, i.e. has a surface which is not fully neutral and is therefore hazardous to the general operator.In conjunction with a flow (and thus force) measuring device, this can indicate that the expected force is less than required and thus a corresponding repositioning of the workpiece or a revision of the cutting parameters to be used for the machining is required.It is also possible that the fault condition is displayed when the area is used without periodic passing, or that in case of repeated faults it is proposed to turn to the manufacturer's "service" (a possible email address or telephone number also appearing on the screen) in order to take immediate and final measures to eliminate these problems.If there are customer service agreements (CSAs) based on the number of transactions performed by the system, the state indicator may indicate that agreed maintenance is required.The e-paper screen EP or the electronic paper is a display intended to emulate ink on paper. Unlike a conventional display, an e-paper does not require backlight to display images because, like a sheet of paper, it uses external light to be visible. As a result, it is readily visible even in direct sunlight, but requires additional illumination in dark environments.The pixels constituting an e-paper display can be realized with different technologies that more or less use the same display principle. One of the most popular methods is electrophoresis in which electrically charged particles are moved through an electric field. Here, the pixels are composed of minute capsules filled with charged pigment particles floating in a dielectric liquid.The electrodes placed under the capsules are capable of moving the pigments according to the applied electric voltage by changing the reflection of the light on the surface of the display, thus displaying the desired image.Once the pixels are polarized, the indicator is able to maintain the image without the need to supply current, and this is a very important feature in the practice of the present invention.It is therefore only necessary to supply current to the indicator in the event of a refresh or update of the image, but even then it is only possible to act on the parts of the indicator (e.g. the area Z1) to be changed, while the state of the remaining parts remains unchanged.Regardless of the technology with which the EP E paper display can be implemented, e.g., gyricon, electrophoretic indicator (EPD), microencapsulated electrophoretic indicator, electrowetting indicator (EWD), electrofluenic indicator, interferometric modulator (Mirasol), plasmonic electronic indicator, only those e-paper indicators are used for use in the present invention that do not require current to keep a particular message displayed.Advantageously, the technology of the e-paper screen EP used can be chosen from those mentioned above, so that the screen displays said information for at least two years, preferably for at least four years, even without the power supply.Advantageously, the technology of the e-paper screen EP can be of the active matrix EPD type. It has been demonstrated that with this technology, what is written on the screen remains readable for at least four years.It should be noted that after 1000 hours without current supply there is a slight contrast drop, which does not impair readability, however. After 1000 hours, no contrast drop was observed.More advantageously, the technology of the e-paper screen EP used can be chosen from those mentioned above, so that even without power supply it displays said information for a substantially unlimited time.As a result, the magnetization indicator 14 is capable of indicating the magnetization state (or a failure state) set last by the control panel 11 even when it is separated from the electropermanent magnetic module 12. This is absolutely advantageous for the safe application of the module 12.As shown in FIG. 4, the e-paper screen RP advantageously includes a second zone Z 2 configured to display time information related to the state displayed in the first zone Z 1.The time information can be, for example, the date and time at which the magnetization state of the module 12 changed to the state shown in zone D 1 or an error occurred.This information may be particularly important to determine the order of loading a sequence of magnetic pallets and thus to operate according to FIFO strategies, as well as to check the average wait time for certain tasksFinally, it is very useful, in the case of mechanical seal problems during machining, to know the date when the specific complete or partial activation has been carried out.Advantageously, the e-paper screen EP may include a third zone Z 3 configured to permanently and unalterably display technical data relating to the electropermanent magnetic module 12 during normal use or otherwise by a user.These technical data comprise, for example, one or more of the following fields: serial number of the electropermanent magnet module, date of manufacture, date of last maintenance, name of the manufacturer, operating voltage, resistance, operating current, weight.In this way, by "writing" the technical data of the area on the e-paper screen EP, cost savings can be achieved in the characterization of the electropermanent magnet module 12 itselfThe e-paper screen EP may be controlled by a control unit CPU-UC, CPU-M, which is connected to the sensors ZC, AM, AP, AMP, FLUX and is configured to determine the magnetization state of the electro-permanent magnet module 12 on the basis of the data obtained from the sensors ZC, AM, AP, AMP, FLUX and to write the at least one item of information about the magnetization state into the e-paper screen EP.Advantageously, control units and control logic are integrated into the e-paper screen EP in order to allow the display of information which is sent from the CPU UC, CPU UM control unit to the screen EP. In this sense, the control units CPU-UC, CPU-UM control the screen EP or "write" it.Naturally, the control logic of the screen EP is only powered when the control panel 11 is connected to the module 12 and during the magnetization / demagnetization phases, since the update activity of the e-paper display is its natural prolongation.FIG. 5 shows a (simplified) logic / physical scheme for deriving the information about the magnetization state which is to be written to the e-paper screen EP.A very complete diagram is shown in Fig. 5, but depending on the case, fewer logical / physical units may also be provided for controlling the e-paper EP according to the present inventionFor example, the e-paper screen EP can be controlled only by a control unit CPU-UC integrated into the electronic control panel 11, which control unit determines the magnetization state information by the measurement values of at least one mains voltage sensor ZC and one current sensor AM in the electronic control panel 11.In this case, a data bus must be provided both in the control panel 11 and in the magnetization indicator 14 (or in the area 12) for communication with the screen EP. Of course, the cable 13 must also pass this information through with a corresponding wiring.The same control unit CPU-UC, which is integrated in the control panel 11, i.e. which controls the magnetization of the module 12 via the power section PW, also writes the magnetization state (or in any case the magnetization state information) on the screen EP only after it has checked that the magnetization state has changed in the desired direction.The CPU UC is the processing unit of the indicator system responsible for processing requests, operating the magnetic system and reporting events.Input devices IN are usually buttons via which a specific action is requested.The output devices OP are normally lamps or screens with which the system state is reported on the panel 11.The network RT is the source of the energy.The power section PW is the device which draws the energy from the network RT and outputs it in a suitable manner to the magnet system.The zero crossing detector ZC is a device which signals the CPU UC the development of the mains voltage.The ammeter AM is the device that measures the current supplied to the load and returns the value to the CPU UC.Typically, the CPU UC knowing the trend of the mains voltage (by the zero crossing detector ZC) activates the power part PW for a certain time in response to a request made via the input device IN, in order to activate the coils of the electropermanent magnetic module 12 connected via the connector C.At the same time, the current measurement via the AM enables the validation of the process being performed. If the measured current has the corresponding amplitude, mean and area characteristics, the CPU UC notifies the proper activation of the magnetic system via the output devices OP and, if not, the system fault condition.This also applies to the case of demagnetization and partial magnetization of the system. The common use of the zero-cross detector ZC and the power section PW makes it possible to modulate the current supplied to the magnetic system in a suitable manner in order to achieve the desired state.At the same time, the current measuring device AM enables the checking of the operation.Generally, the output device OP informing the operator of the magnetic state of the system is integrated into the control panel 11.In this configuration, the control unit CPU-UC can also write the magnetization result (i.e., the magnetization state information) directly to the e-paper screen EP via the BUS in both the control panel and the magnetic state indicator 14 (i.e., on the electropermanent magnetic module 12) via the connector.By disconnecting the connector, the information on the screen EP is permanently retained without the module 12 having to be supplied with powerAlternatively, the e-paper EP is controlled exclusively by a control unit CPU-M integrated into the electropermanent magnetic module 12 (or indicator 14). It itself detects the information about the magnetization state by reading a current sensor AP in the electropermanent magnet module 12 (or in the indicator 14).A "mixed" mode is also possible in which both the CPU UC on the panel 11 and the CPU-M on the module 12 independently check the magnetization of the surface by separate current measurements (i.e. AM and AP), and one of the two (i.e. the CPU-M on the surface) writes the information to the e-paper screen EP only if the checks match.Advantageously, in addition to or as an alternative to the above-described amperometric sensors, a magnetic flux detector FLUX may be provided, which is connected to at least one magnet MAG (or pole 120) of the electropermanent magnet module 12.The signal of the detector FLUX suitably amplified by AMP can either be used directly by the control unit CPU-M on board the module and / or sent via the BUS to the control unit CPU-UC of the control panel 11 in order to check (or further check) the state of magnetization / demagnetization before the information about the state of magnetization is written to the e-paper screen EP.To complete the description in Fig. 5, it should be mentioned that the control unit CPU-M may be connected to a static memory MS storing the history of the magnetic states written on the e-paper screen EP, advantageously connected to a time stamp.This could allow the history of total activations / partial activations / deactivations / errors to be stored, which is particularly useful in the case of poor workpiece fit, along with the time and day data identifying the time window in which a particular problem could have occurred.The time stamp (either that possibly written in the static memory MS or that displayed in the area Z2 of the e-paper screen EP) can be obtained from a real-time clock RTC connected to the CPU-M (in this case possibly powered by a battery, also rechargeable, which is charged when the control panel 11 is connected to the module 11) or to the CPU-UC or both.It has been mentioned that the control panel 11 is configured to partially or fully magnetize (or degauss) the electropermanent magnet module 12.Moreover, the electrical terminal 13 coupled to the connector C is advantageously removable and comprises the magnetization wiring of the electropermanent magnetic module 12 (i.e. the power supply) and optionally the wiring of a data bus.Various forms of implementation of the invention have been described, but others may be designed with the same innovative concept.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 2742363 A1 [0024, 0028]

Claims

An electropermanent magnetic system (10) comprising an electropermanent magnet module (12) and an electronic control panel (11) configured to supply an electric current to the electropermanent magnet module (12) to magnetizing or demagnetize it, and an electrical connection (13) between the control panel (11) and the electropermanent magnet module (12), the electropermanent magnet module (12) comprising a hard-bonded magnetization indicator (14), characterized in that the magnetization indicator (14) comprises an e-paper screen (EP) configured to display, in a first zone (Z1), at least one item of information relating to the state of magnetization of the electropermanent magnet module (12), Even if the e-paper screen (EP) is not activated.The system according to the preceding claim, wherein the e-paper screen (EP) displays said information even without power supply for at least two years, preferably at least four years.The system according to claim 1 or 2, wherein the e-paper screen (EP) comprises a second zone (Z2) configured to display time information related to the state displayed in the first zone (Z1).The system according to any one of the preceding claims, wherein the e-paper screen (EP) comprises a third zone (Z3) configured to permanently display, during normal use, invariable technical data of the electropermanent magnetic module (12).The system of claim 4, wherein the technical data comprises one or more of the following fields: serial number of the electropermanent magnet module, date of manufacture, date of last maintenance, name of the manufacturer, operating voltage, resistance, operating current, weight.The system according to any one of the preceding claims, wherein the e-paper screen (EP) is controlled by a control unit (CPU-UC, CPU-M) connected to sensors (ZC, AM, AP, AMP, FLUX) and configured to determine the state of magnetization of the electro-permanent magnet module (12) on the basis of data obtained from the sensors (ZC, AM, AP, AMP, FLUX) and to write at least one item of magnetization state information on the e-paper screen (EP).The system according to claim 6, wherein the e-paper screen (EP) is controlled by a control unit (CPU-UC) integrated in the electronic control panel (11), which determines the magnetization state information by the measurement values of at least one of a mains voltage sensor (ZC) and a current sensor (AM) in the electronic control panel (11).The system according to claim 6, wherein the e-paper screen (EP) is controlled by a control unit (CPU-M) integrated in the electropermanent magnet module (12), which determines the magnetization state information by reading a current sensor (AP) in the electropermanent magnet module (12).The system according to claim 7 or 8, wherein the control unit (CPU-UC, CPU-M) verifies the magnetization state information by the at least one magnetic flux detector (FLUX) connected to the at least one magnet of the electropermanent magnet module (12) before being written on the e-paper screen (EP).The system according to claim 8, wherein the control unit (CPU-M) is associated with a static memory (MS) storing the history of magnetic states written on the e-paper screen (EP).The system according to claim 8, wherein the control unit (CPU-M) is connected to or includes a real-time clock (RTC) from which it reads out the current time and date before writing the magnetization state information on the e-paper screen (EP), and which writes the obtained time information at least in the second zone (Z2).The system according to any one of the preceding claims, wherein the control panel (11) is configured to partially or fully magnetize the electropermanent magnet module.The system according to any one of the preceding claims, wherein the electrical connection (13) is detachable and comprises a magnetization wiring of the electropermanent magnetic module (12) and optionally a wiring of a data bus.The system of any preceding claim, wherein the magnetization state information comprises at least the following three states: a magnetization state, a demagnetization state, and a fault state.

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