Method for detecting material loss, in particular wear detection, and arrangement for carrying out the method - Patent Application 20070122990

Abstract

At least one, preferably at least two, bistable magnetic bodies (1) are adapted to undergo magnetization reversal in the dynamic magnetic field of the reading device (2) and are positioned in the material wear area. Material loss is accompanied by a decrease in the number of detected bistable magnetic bodies (1). The presence of the bistable magnetic bodies (1) is detected by the reading device (2) based on evaluation of the magnetization reversal response of the bistable magnetic bodies (1) when a typical narrow local maximum (e) is searched for in the received signal. Advantageously, a triangular-shaped magnetic field is used, which has an essentially linear excitation increase and conveniently separates the local maxima of the multiple bistable magnetic bodies (1). The reading device (2) can be a permanent part of the system or a portable device used during maintenance and inspection of a specific device. The miniaturization and rapid evaluation method of the bistable magnetic bodies (1) enable a wide range of applications, particularly in transportation, handling, and lifting technology.

Description

[Technical Field]

[0001] The present invention relates to a method for detecting material loss, in particular for detecting loss of solid material in the course of gradual wear using a detection element arranged in a material layer. The subject of the present invention is also an arrangement for carrying out the new method for detecting material loss, the system of which can be used for moving and non-moving elements, in particular machine elements, parts and components in transport and lifting technology, mining, energy industry, etc. For the US region, this application is a continuation of the parent application EP22166892.4, which discloses the general principle of measuring various physical quantities using a bistable magnetic wire. [Background technology]

[0002] To determine the wear rate and assess the service life of various components, parts and tools, methods have been used that use detection methods or interruptions of electrical circuits passed through layers of material in the area of ​​wear, or methods that determine the presence of a detection element or elements in the area of ​​wear.

[0003] DE 198070004 A1 describes a sensor in the tire that communicates contactlessly with a reading unit to which wear data is transmitted. Disadvantages of this arrangement are the complexity of the wear assessment and the transmission of data to a module inside the vehicle.

[0004] The system according to document DE102009010983 A1 uses at least one electric or magnetic element located in a specific layer of the component material. The electric or magnetic response of the electric or magnetic element is detected with the aid of a detector. When the component wears down to the layer where the electric or magnetic element is located, the electric or magnetic response is lost, and this state is evaluated as wear down to the respective layer level. This document describes a general principle of wear detection, which has also been described in other older documents. However, when this general principle is actually implemented, surrounding electric and magnetic fields and random phenomena significantly complicate the detection of the electric or magnetic response. Solutions to these problems are not provided in this document.

[0005] AU2014200336 A1 describes RFID chips arranged in multiple material layers in the wear area of ​​a conveyor belt, preferably in multiple locations on the conveyor belt profile. This document provides a partial solution to the aforementioned problem by enabling an RFID reader to detect the presence of an RFID chip with specific identification information and detect when the conveyor belt layers are cut and the RFID chip falls off or breaks at the corresponding location. The drawbacks are the relatively large size of the RFID chip, which determines the discernible thickness of the wear at each step, and the relatively complex nature of reading the RFID code, especially at high conveyor belt speeds.

[0006] A technical solution for wear detection that can be widely used in various applications, uses a small detection element, and at the same time has high reliability for contactless information transmission even in noisy environments with various electric and magnetic sources is desired, but is not known. Summary of the Invention

[0007] The aforementioned drawbacks are largely eliminated by a method for detecting material loss, particularly wear detection, in which at least one detection element is placed in the material wear area and the material loss is then assessed by detecting the presence or absence of the detection element using a reading device according to the present invention. The detection element is a bistable magnetic body adapted to undergo a magnetization reversal in the excitation field of the reading device. When detecting material loss, the reading device detects the presence of the bistable magnetic body by evaluating the response of the magnetization reversal of the bistable magnetic body. Based on this response, the presence of one or more bistable magnetic bodies in the wear area is determined. If there is no corresponding signal, it is assessed that material has worn away within or through the layer in which the corresponding bistable magnetic body is located. It is not necessary to explicitly identify the detection element. In certain applications, all bistable magnetic bodies may be identical; that is, even if there is no unique identification between them, it is sufficient to simply measure their number, since it can always be reliably assumed that each layer gradually wears away. Configurations in which individual bistable magnetic bodies are identified and their number detected allow the correctness of the gradual loss of bistable magnetic bodies to be checked.

[0008] Bistable magnetic materials are known for measuring various physical quantities and positions, forming passive elements that react to changes in position or physical quantities by reversing their magnetization. In the present invention, it is not necessary to evaluate the physical quantity as a manifestation of a change in state of the bistable magnetic material; it is sufficient to evaluate the presence or absence of the bistable magnetic material. This simplifies and accelerates detection.

[0009] An important advantage of the present invention is the small size and relatively low cost of the bistable magnetic body, preferably in the form of a bistable magnetic wire. The bistable magnetic wire typically has a diameter of less than 50 μm, preferably less than 25 μm, and particularly preferably less than 15 μm. Therefore, it is also called a bistable magnetic microwire or bistable magnetic hair. This allows for the creation of multiple detection layers with fine dimensional gradients, which can significantly improve the accuracy of wear measurements, especially for solid materials where wear is a risk, even if a thin layer of material is lost. Another advantage is that the small size of the bistable magnetic body has relatively little effect on the mechanical and strength properties of each component. Bistable magnetic bodies in the form of wires, microwires, or strings are resistant to external influences and can be easily inserted into materials without risk of damage, since they do not require a power source, control circuit, or code carrier, as, for example, RFID elements.

[0010] The mutual spacing of the individual detection layers is selected depending on the required measurement range. For example, they can be spaced in millimeters for tires, 10 mm or more in total (for truck casings), or tenths to hundredths of a millimeter for metal parts. Typically, the available depth H of the abrasive material is divided evenly over the selected number of layers according to the relationship: H = x . d or H = (x‐1) . d where x is the number of bistable magnetic particles and d is the distance between the layers. Depending on the wear characteristics of a particular material or the nature of the critical conditions in a given device, the distribution of layers with bistable magnetic particles can also be non-uniform.

[0011] In some embodiments, it may be advantageous for at least some layers, such as the final or first layers, or even all wear layers, to comprise multiple bistable magnetic elements. Such embodiments can help to increase reliability or detection accuracy while using the small dimensions and low cost of bistable magnetic elements, particularly in the form of microwires.

[0012] The moment when the signal disappears on the reading device occurs when the bistable magnetic material falls off the corresponding layer, when this layer is exposed due to wear and does not have the mechanical support for the bistable magnetic material to remain in place, or when the structure of the bistable magnetic material is disturbed, i.e., when part of the bistable magnetic material remains in the corresponding layer but the bistable magnetic material is disturbed (e.g., grounded), and the received signal on the reading device changes substantially or disappears completely. This detection mechanism means that the absence of a bistable magnetic material is understood here as the absence of a functional bistable magnetic wire that can cause the expected response in the receiving device. This loss of function may later precede the moment when the bistable magnetic material of the respective layer falls off completely.

[0013] When bistable magnets are detected in increasingly shorter materials, the gradual decrease in response amplitude (usually down to the background limit) can also be assessed.

[0014] When measuring the presence of bistable magnetic materials, magnetic excitation with a triangular signal is advantageously used, as described in the applicant's previous patent application EP 22166892.4, typically with a symmetric triangular signal and an asymmetric excitation field. This process significantly simplifies the evaluation of the measured response signal, allows measurements at high frequencies, and overcomes some of the drawbacks known in the art, where the evaluation of the response was unstable as a result of the complex magnetic evolution during the magnetization reversals of multiple domains in a bistable magnetic material.

[0015] The presence of a bistable magnetic object is detected by measuring the induction response, with each bistable magnetic object appearing as a single peak within a half-cycle of the excitation magnetic signal. The detected response peak is highly recognizable, with an amplitude at least twice that of the spurious background and typically at least five times that of the background noise. Such sharp peaks are easy to diagnose and are not subject to undesirable interference from ambient electromagnetic fields, which are always present in common industrial practice and difficult to predict accurately in advance. As shown in the example diagram, the response peaks are easily and clearly identifiable in the received signal. This makes the evaluation fast, accurate, and unaffected by various secondary effects, making it possible to diagnose multiple bistable magnetic objects with discretely separated response peaks within a half-cycle of the excitation magnetic signal. Narrow peaks in the received signal are a manifestation of jump magnetization reversals at certain amplitudes of the excitation magnetic field, gradually increasing linearly and periodically.

[0016] When devising this technical solution, it is not necessary to use complex numerical methods to analyze the course of the measured response in order to detect the response; it is sufficient to set an amplitude limit, the exceeding of which in the response within one excitation half-wave identifies the presence of a bistable magnetic body.

[0017] In theory, since measurements are made only during half a period of the excitation, the time required for the reader to reach the bistable magnetic body or group of bistable magnetic wires is extremely short, orders of magnitude shorter than when reading, for example, an RFID chip according to the prior art. This increases the applicability of the invention in moving parts, such as rotating, sliding or circulating components, such as wheels, rotors, tires, pulleys, bands, belts, ropes, etc., since the excitation signal can have a high frequency that is several times or even an order of magnitude higher than the rotation frequency of the component or the generation frequency of the part of the component that has the bistable magnetic body placed within the range of the reader.

[0018] At the same time, it is advantageous to select and set the frequency of the excitation field so that multiple waves of the excitation signal are effectively transmitted during the time window in which the bistable magnetic body or groups of bistable magnetic bodies are within the range of the reading device. Outside this time window, peaks from the bistable magnetic bodies are not recognized in the received response. In principle, and without technical problems, relatively high excitation frequencies can be applied, so that within half a wave of the excitation magnetic signal, no single bistable magnetic body is repeatedly received, which would otherwise lead to a false interpretation of the number of bistable magnetic bodies in the wear area.

[0019] When selecting the excitation frequency, the frequencies of peripheral devices that may affect the electromagnetic field within the range of the reading device can be taken into account, and the excitation frequency can be selected outside the frequency range of the peripheral devices. For example, for devices powered by the public power grid, the excitation frequency is set outside 50 Hz and ultimately outside harmonic multiples of this frequency. If the frequency is variable, for example in frequency converters for starting and after-running motors, the entire adjustable frequency spectrum can be taken into account. For example, in automotive applications, such a frequency can be selected outside the band generated by nearby magnetic sensors, such as ABS sensors in wheel retraction bearings.

[0020] Due to the nature of the disclosed method, for moving components and non-moving reading devices, the maximum allowable material loss is sufficient if the last bistable magnetic element or group of bistable magnetic elements remains in its respective layer until the final critical wear level. That is, the maximum allowable wear level is determined when the penultimate bistable magnetic element or group of bistable magnetic elements falls off or becomes dislodged. In this configuration, the loss of the received signal during component movement occurs until the time window in which the last bistable magnetic element is within range of the reading device. Therefore, the loss of the received signal is not interpreted as the maximum allowable wear amount, but as a condition in which the diagnostic time window has been exceeded. At the same time, this allows for the complete loss of signal, i.e., even within the expected time window, to be determined as a failure of signal transmission or signal processing. In another embodiment, the loss of all bistable magnetic elements can signal a critical level of wear. In this case, it may be appropriate for another data source (another sensor) to provide information that the zone in which the bistable magnetic elements are located is within range of the reading device.

[0021] In a preferred process, a reading device can be directly or indirectly connected to the movement control or sensor of each component. Once information about the component's movement is obtained, the recurrence frequency of the time window can be calculated and compared with the frequency of the received response. In such a case, it can be determined, for example, that the component's movement is repeated but no response is received, signaling another fault in the diagnostic process. Alternatively, the frequency of the excitation magnetic signal can be changed depending on the information from the movement control or sensor of each component. For example, data from an elevator frequency converter, ABS sensor, or turbine speed sensor can be used in systems with existing hardware components, eliminating the need for additional sensors. A specific example is a process in which the frequency of occurrence of a time window in which a response is received at the start of a diagnostic process is recognized, and the frequency of the excitation magnetic field is adjusted up or down according to a set algorithm during the next measurement cycle.

[0022] Loss detection can include identifying the part or component in a stationary position in such a way that the bistable magnetic body is permanently within the range of the reading device. This depends on coincidence or slippage for systems with different motion interruptions. In such cases, the magnetic field excitation can be interrupted, since the detection output is the same data regarding the number of functioning bistable magnetic bodies. According to this program, if the detected component moves based on data from the host system, the excitation at the reading device is resumed or the excitation is repeated at different time intervals.

[0023] A method for detecting material loss, particularly wear detection, is possible and advantageous in a mode in which a bistable magnetic material is pre-attached to the part or component being inspected, such as an elevator rope, and detection is performed during inspection using a portable reading device. In such a process, the bistable magnetic material is so small and inexpensive that the investment costs for detection are essentially negligible, and the portable reading device is used in several locations. The operator places the reading device at a predetermined location, such as on the elevator rope guide, and starts the elevator so that the location where the bistable magnetic material is located passes by the reading device, and the measurement value is immediately evaluated. One rope pass is sufficient. In other embodiments, such as when measuring tire wear, a permanently installed reading device is advantageous if detection is not performed continuously, but rather at predetermined intervals during or immediately after tire movement.

[0024] The above-mentioned drawbacks of the prior art are substantially eliminated by an arrangement for material loss detection per se, in particular wear detection, which comprises at least one detection element and a reading device for detecting the presence of the detection element, the at least one detection element being arranged in the material loss area according to this invention, characterized in that the detection element is a bistable magnetic material adapted to undergo magnetization reversal in the excitation field of the reading device, and the detection element is within the range of the reading device at least during the detection time window.

[0025] As disclosed in the detection method, the reader is adapted to assess the presence of at least one bistable magnetic material, preferably at least two or three bistable magnetic materials, where a group of bistable magnetic materials is used, these are arranged in layers in the direction of the material loss gradient during wear.

[0026] The bistable magnetic wire preferably takes the form of a bistable magnetic wire with a diameter of less than 50 μm and a length of at least 100 times, preferably at least 1000 times, its diameter. The elongated bistable magnetic wire is advantageously positioned perpendicular to the material loss gradient so that a shock change occurs when material is lost to the respective layer, i.e., the bistable magnetic wire is either released or blocked to a state where it cannot respond to an excitation magnetic signal. The bistable magnetic body is adapted for magnetization reversal by a single Barkhausen front jump from the first end to the second end or vice versa, and the excitation element and the bistable magnetic wire are positioned relative to each other such that the amplitude of the magnetic field excited by the excitation element at the first end is different from the amplitude of the magnetic field excited by the excitation element at the other end.

[0027] A typical structure of a bistable magnetic material includes an amorphous metal core and a cover, e.g., a glass cover, whose outer diameter is less than three times the diameter of the metal core. The thickness of the glass cover can reach 1-20 μm. The glass cover, i.e., the glass surface layer, protects the metal core from electrical contact with the surrounding environment and from aggressive chemical environments, making the bistable magnetic material highly versatile. This invention can be used in the mining and energy industries, where the bistable magnetic material is insensitive to the external environment and at the same time inert to the surrounding environment, e.g., oil in the lubrication system. For example, in chip processing tools, the loss of the detection properties of the bistable magnetic wire due to high temperatures (above the Curie temperature) indirectly indicates component damage.

[0028] In one advantageous configuration, the configuration can be supplemented with a component movement sensor having a positioned bistable magnetic body or can be connected to a higher-level system that controls or detects the movement of the respective component. In another configuration, the reader can function as a speed sensor for a higher-level control system, where each material loss detection sequence signals one cycle, i.e., one revolution of the wheel or one revolution of the conveyor belt.

[0029] The reading device typically includes a power element that, according to its instructions, sends a power supply to the excitation element regulated to obtain a triangular excitation signal. An evaluation element in the reading device acquires and analyzes the response received from the bistable magnetic material, primarily determining the number of peaks within the half-wave of the excitation magnetic signal. This number is then assigned a loss state according to a programmed interpretation rule that takes into account the specific depth of the layer containing the bistable magnetic material.

[0030] To measure the response, the antenna of the excitation element can be used, but preferably the system also includes a separate receiving element, for example in the form of a receiving coil, in which case the excitation element can be a primary coil and the receiving element is formed by a secondary coil, which can be connected to an amplifier and an evaluation unit.

[0031] The major advantages of the present invention are the high speed of measurement, the reliability of detection even in the case of short time windows of moving components, the interference-resistant contactless signal transmission and therefore the wide range of applications in various fields. Also, the simple method of evaluating the amplitude peaks only when the signal exceeds a set value allows the cost of the device to be reduced. [Brief explanation of the drawings]

[0032] The present invention will be described in more detail through Figures 1 to 7. The magnitude of the response amplitude and the shape of the excitation element specifically shown are merely examples and should not be construed as narrowing the claimed protection of the present invention. Figure 1 shows a block schematic diagram of a configuration with three bistable magnetic bodies in successive layers of different material wear. For clarity, the layer spacings are not to scale relative to the thickness of the indicated bistable magnetic bodies. FIG. 2 shows a simplified diagram of wear detection in an elevator drive pulley. Figure 3 shows the time windows recorded while the pulley was rotating. The part marked B is the time window when no response signal was received, and the part marked A is the time window when a signal was received. Figure 4 shows the signal received from a single bistable magnetic object during two consecutive magnetic excitation waves. The peaks corresponding to the presence of a bistable magnetic object are marked with an e. The dashed line shows an example of the value set at which the response of a bistable magnetic object is evaluated to be present in the received signal. Figure 5 shows the sequential signals received from 5-1 bistable magnetic bodies during a half-wave magnetic excitation wave. The sequence shows wear down to the final layer. FIG. 6 shows an example of using two excitation coils in a reading device when measuring tire wear. The signals in Figure 7 demonstrate that, in principle, equally readable and clearly interpretable responses can be achieved with different bistable magnetic materials. DETAILED DESCRIPTION OF THE INVENTION

[0033] Example 1 In this example, wear of the drive pulley of an elevator mechanism, in which the rope is driven and braked by friction, is detected according to Figures 1 to 5. The state of the pulley also indirectly indicates rope wear. Two bistable magnetic microwires 1 are glued in succession, layer by layer, to the outer periphery of the pulley, where they contact the rope.

[0034] In this example, reader 2 is permanently attached to the outer periphery of the pulley. The pulley rotates during elevator operation, periodically bringing the location of the attached bistable magnetic wire within range of reader 2. In this example, a program controls the detection so that reader 2 is activated once a day when the elevator moves. The detection of the presence of two bistable magnetic bodies 1 represents a normal condition where wear does not exceed a safe level. The detection of one bistable magnetic wire indicates wear below a determined safe level. If no bistable magnetic body 1 is detected during the time window, a fault condition is detected.

[0035] In this example, the frequency of the excitation field is stable at a level of about 1000 Hz, and a relatively slow pulley speed is sufficient.

[0036] Example 2 The system measures tire wear on a vehicle using a group of bistable magnetic elements 1 inserted into the tire tread. The reader 1 is installed inside a casing and transmits the acquired data to a communication module near the tire. The activation frequency of the reader 2 is between 10 and 1000 Hz, depending on whether the measurement is performed while moving or stationary. The excitation frequency of the rotating wheel can also be set to avoid the actual frequency of the ABS sensor signal or other background signals at a sufficient distance.

[0037] Example 3 To detect wear on a conveyor belt, groups of bistable magnetic materials 1 are placed at several locations on the belt profile, and each group is evaluated by a separate reading device 2 over a corresponding width of the conveyor belt, thereby detecting wear at several locations within the width of the conveyor belt.

[0038] Example 4 In this example, wear of the turbine main bearing is detected. The advantage of using the bistable magnetic wire 1 is that it works with oil lubrication even in high temperature environments and the debris of the bistable magnetic wire 1 after grinding does not pose a threat to the lubrication system.

[0039] Example 5 In systems with many wear points, the reliability and service life of the system can be detected by setting bistable magnetic particles to fall into the lubrication system, trapping them in a filter, and reading the number of trapped bistable magnetic particles. When the number of trapped bistable magnetic particles reaches a set number, a critical wear state is reported without installing reading devices at multiple locations in the system. [Industrial Applicability]

[0040] The industrial applicability is clear. The present invention allows for repeated industrial detection of material loss by detecting the presence of one or more bistable magnetic bodies in the material loss region. The present invention is primarily applicable to transportation technology, cable cars and elevators, tool evaluation in industrial production, and safety systems for various critical equipment. [Explanation of symbols]

[0041] Reference Code List 1 - bistable magnetic material 2 - Reading Device A - Time window with received response B - No Response Time e- Local peak of response signal

Claims

1. 1. A method for material loss detection, in particular wear detection, in which at least one detection element is placed in a wear area of ​​the material, and then the material loss is assessed by detecting the presence of the detection element using a reading device (2), comprising: the sensing element is a bistable magnetic material (1) adapted to undergo magnetization reversal in a dynamically changing excitation magnetic field of a reading device (2); The presence of the bistable magnetic material (1) is detected by a reading device (2) based on evaluation of the response of the magnetization reversal of the bistable magnetic material (1) in the received signal. A method characterized by:

2. 2. The method for material loss detection, in particular wear detection, according to claim 1, characterized in that an amplitude in the received signal that exceeds the background level by at least two times is considered to be a response of the bistable magnetic body (1) in the received signal.

3. 3. A method for detecting material losses, in particular wear, according to claim 1 or 2, characterized in that the reading device (2) periodically excites a magnetic field having a triangular signal shape.

4. 4. The method for material loss detection, in particular wear detection, according to claim 3, characterized in that the excitation frequency is in the range of 1 to 10,000 Hz, preferably 133 Hz, particularly preferably outside the electromagnetic field frequencies of peripheral devices.

5. 5. A method for material loss detection, in particular wear detection, according to claim 1, characterized in that the excitation frequency is set so that at least five magnetic excitation waves are emitted within the bistable magnetic body in the time window of detection, and preferably 60% of the results of the most consistent measurements are used for the analysis of the repeated responses in one time window.

6. 6. A method for material loss detection, in particular wear detection, according to claim 1, characterized in that the number of measured local peaks (e) of the response signal during one excitation half-wave corresponds to the number of bistable magnetic bodies (1) present.

7. 7. A method for material loss detection, in particular wear detection, according to claim 6, characterized in that the local peak (e) is determined by exceeding a set value of the response amplitude of the received signal.

8. 8. The method for material loss detection, in particular wear detection, according to claim 1, characterized in that the excitation frequency of the reading device (2) varies depending on the moving or rotating speed of the component having the bistable magnetic material (1).

9. 9. A method for detecting material loss, in particular wear detection, according to any one of claims 1 to 8, characterized in that a portable reading device (2) is used, which is temporarily brought close to the material loss area during inspection or testing.

10. 9. A method for material loss detection, in particular wear detection, according to any one of claims 1 to 8, characterized in that a permanently arranged reading device (2) is used, which reading device (2) is activated according to a set timing algorithm or according to a set operating interval of the device comprising the component in which the material loss has been detected.

11. 1. An arrangement for material loss detection, in particular wear detection, comprising at least one detection element and a reading device (2) for detecting the presence of the detection element, the detection element being arranged in a material loss area, the detection element being a bistable magnetic body (1) adapted to undergo magnetization reversal in an excitation field of the reading device (2), the bistable magnetic body (1) being within the detection range of the reading device (2) in at least one time window.

12. 12. Arrangement for material loss detection, in particular wear detection, according to claim 11, characterized in that the bistable magnetic body (1) is a bistable magnetic wire with a diameter of less than 50 μm and a length of at least 100 times, preferably at least 1000 times, its diameter.

13. 13. Arrangement for material loss detection, in particular wear detection, according to claim 11 or 12, characterized in that the bistable magnetic body (1) has an elongated shape and is arranged substantially perpendicular to the material loss gradient.

14. 14. The arrangement for detecting material loss, in particular wear detection, according to any one of claims 11 to 13, characterized in that the excitation element of the reading device (2) and the bistable magnetic body (1) are arranged in a mutual position, and the magnitude of the amplitude of the magnetic field excited by the excitation element at a first end of the bistable magnetic body (1) is different from the magnitude of the amplitude of the magnetic field excited by the excitation element at the other end of the bistable magnetic body (1).

15. 15. The arrangement for material loss detection, in particular wear detection, according to any one of claims 11 to 14, characterized in that it comprises at least three bistable magnetic bodies (1), preferably at least five bistable magnetic bodies (1), which are arranged in different layers one after the other in the material loss direction.

16. 16. The arrangement for material loss detection, in particular wear detection, according to any one of claims 11 to 15, characterized in that the reading device (2) is arranged on the moving component and is connected to the evaluation module and / or the display module by a contactless communication channel.

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