Beater gap sensor device for refiner equipment and calibration method

Abstract

The invention relates to a sensor device (1) comprising a transducer (3) adapted to generate a magnetic field (MF), the sensor device (1) being configured to measure a beating gap (G) between a first refining disc (5) and a second refining disc (7) of a refiner arrangement (9) and to be mounted in the first refining disc (5), the sensor device (1) comprising a magnetic pole (13), a coil assembly (15) and a measuring head (11') configured to be set in a calibration position relative to the second refining disc (7) for calibration of the sensor device (1). The measuring head (11') comprises an outer end (10') made of a non-magnetic material configured to be positioned in abutment with the second refining disc (7) in a calibration sequence. The invention also relates to a method of calibrating said sensor device (1).

Description

Technical Field

[0001] The present invention relates to the sensor device according to claim 1 and the method for calibrating the sensor device according to claim 8.

[0002] The present invention may also relate to a data medium storage program for a fine grinding mill and a pulping gap sensor device suitable for calibrating the fine grinding mill.

[0003] This invention primarily relates to the pulp production industry utilizing refining mill equipment. It also relates to the industry of producing a beating gap sensor configured to measure the beating gap between the grinding surfaces of the refining discs of a refining mill. Background Technology

[0004] The current sensor device for measuring the distance between grinding discs includes a magnetic transducer, preferably operating on the principle of magnetoresistive reluctance, the transducer including magnetic poles contained in a sleeve forming a measuring head.

[0005] The current sensor device can be configured to contact an opposing polished surface during calibration, and known methods for achieving accurate calibration of the sensor device are provided.

[0006] An example of a slurry gap sensor is shown in the applicant's US 6,657,427B2. The sensor is mounted to be movable in the axial direction of a first slurry disc and to contact an opposing second slurry disc. The sensor in US 6,657,427B2 works well but still requires further development. Summary of the Invention

[0007] There is a need to improve the accuracy of determining the dimensions of the beating gap in refiners used in pulp production, where wear and tear of the measuring head poses a problem to measurement accuracy in other ways.

[0008] There is a purpose to provide sensor devices configured for precise calibration.

[0009] There is a purpose to provide a sensor device that functions in a rigid manner and provides cost-effective functionality.

[0010] The contact can occur in other locations relative to the grinding disc, rather than at the location of the existing technology sensor measuring head used for existing technology calibration. Such contact between grinding disc sections or rods may mislead the system into making the correct calibration.

[0011] The objective, or at least one of the objectives, has been achieved by a sensor device comprising a transducer adapted to generate a magnetic field, the sensor device being configured to measure the pulping gap between a first and a second grinding disc of a fine grinding mill apparatus and configured to be mounted in the first grinding disc, the sensor device comprising magnetic poles, a coil assembly, and a measuring head configured to be positioned in a calibration position relative to the second grinding disc for calibration of the sensor device, wherein the measuring head includes an outer end portion made of a non-magnetic material configured to abut against and be positioned against the second grinding disc in a calibration sequence.

[0012] Alternatively, the coil assembly is arranged around the magnetic pole.

[0013] Alternatively, the first grinding surface of the first fine grinding disc faces the second grinding surface of the second fine grinding disc.

[0014] Alternatively, the pulping gap is defined between the first grinding surface of the first fine grinding disc and the second grinding surface of the second fine grinding disc.

[0015] Alternatively, the magnetic field is generated around the magnetic poles.

[0016] Alternatively, a non-magnetic material is constructed to abut against a second grinding surface of a second fine grinding disc for use in the calibration sequence.

[0017] Alternatively, the calibration sequence is performed during the rotation of the second polishing disc and / or the rotation of the first polishing disc.

[0018] This method achieves time savings and cost-effective operation of the fine grinding mill equipment.

[0019] Alternatively, the non-magnetic outer end surface of the measuring head is configured as a grinding surface facing the second fine grinding disc during use of the sensor device.

[0020] Alternatively, the measuring head forms part of a sleeve assembly in which magnetic poles are housed, the sleeve assembly including an outer end portion comprising a non-magnetic material configured to abut against a second fine grinding disc.

[0021] Alternatively, the magnetic poles are mounted in a sleeve assembly and coil assemblies are arranged around the magnetic poles.

[0022] Alternatively, the outer end of the sleeve device may be referred to as the non-magnetic sleeve end.

[0023] Alternatively, in addition to the nonmagnetic sleeve end which comprises a nonmagnetic material, the sleeve device may also include a magnetic material.

[0024] Alternatively, when the sensor device has been mounted to the first grinding disc, the end of the non-magnetic sleeve protrudes from the first grinding surface to the measuring part.

[0025] Alternatively, the magnetic poles and / or sleeve devices and / or non-magnetic sleeve ends may be made of stainless steel.

[0026] Alternatively, the sensor device is an inductive proximity sensor.

[0027] Alternatively, the sensor device is coupled to a gap measurement conversion circuit configured to convert changes in the magnetic field into electrical signals based on changes in the pulping gap between the measuring head and the second fine grinding disc.

[0028] Alternatively, the outer end portion of the magnetic pole, which does not contain non-magnetic material, forms an end portion surface facing the second polishing surface.

[0029] Alternatively, the non-magnetic sleeve end forms a sleeve end surface facing the second grinding surface.

[0030] Alternatively, the first and second polishing discs are configured to move toward each other to change the pulping gap.

[0031] Alternatively, the first and second grinding discs are arranged on a rotation axis oriented orthogonal to the first and second grinding surfaces.

[0032] Alternatively, at least the first grinding disc is configured to move toward the second grinding disc.

[0033] Alternatively, the gap measurement conversion circuit is coupled to a polishing disc driver configured to move at least the first polishing disc toward and / or away from the second polishing disc along the axis of rotation for adjusting the pulping gap.

[0034] Alternatively, the gap measurement conversion circuit is coupled to the fine grinding disc position sensor to record the relative positions of the corresponding first and second fine grinding discs.

[0035] Alternatively, the gap measurement conversion circuit is coupled to a control circuit configured to control the fine grinding disc driver to move at least the first fine grinding disc along the axis of rotation.

[0036] Alternatively, a measuring head positioned in contact with the second grinding disc provides a first distance value between the first and second grinding surfaces, which is recorded by a measurement conversion circuit.

[0037] Alternatively, the first distance value is referred to as the distance by which the non-magnetic sleeve end protrudes from and transverse to the first grinding surface, such as 0.5 / 0.5 mm or any other suitable value.

[0038] Alternatively, the outer end of the magnetic pole is configured to be flush with the first polished surface.

[0039] Alternatively, the outer end of the magnetic pole is positioned inside or outside the first polishing surface.

[0040] Alternatively, the control circuit is configured to control the polishing disc driver according to the second distance value to provide at least the first polishing disc to move along the axis of rotation, thereby achieving an effective pulping gap value, for example, 5 mm (in the case of a first distance value of 0.5 / 0.5 mm, the second distance value is 4.5 / 4.5 mm, thereby achieving an effective pulping gap value of 5 mm).

[0041] Alternatively, the gap measurement conversion circuit is configured to convert a first magnetic field value into a first electrical signal, which is related to a first distance value.

[0042] Alternatively, the gap measurement conversion circuit is configured to convert a second magnetic field value into a second electrical signal, which is related to a second distance value.

[0043] Alternatively, the gap measurement conversion circuit is configured to record and convert the magnetic field change of the third magnetic field value based on the third distance value when the pulping gap undergoes a change (e.g., due to wear of the grinding surface) to become a third distance value different from the effective pulping gap value.

[0044] Alternatively, the gap measurement conversion circuit is configured to convert a third magnetic field value into a third electrical signal, which is related to a third distance value.

[0045] Alternatively, the gap measurement conversion circuit is configured to command the control circuit to enable the fine grinding disc driver to move the first and / or second fine grinding discs toward each other to adjust a third distance value, thereby achieving an effective pulping gap value, i.e., adjusting the pulping gap to the second distance value, which is effective for optimal grinding.

[0046] Alternatively, when the sleeve end surface of the measuring head abuts the second ground surface, the gap measurement conversion circuit records the contact and calibrates the sensor device.

[0047] In this way, the calibration of the sensor device can be performed reliably, while the important magnetic materials of the magnetic poles and sleeve device are not worn away, and the effective function of the sensor device is preserved.

[0048] In other words, for the sensor device to function rigidly and cost-effectively, magnetic materials are important for achieving accurate and stable measurement of the pulping gap between the first and second grinding surfaces.

[0049] Alternatively, the coil assembly is applied around the magnetic poles and coupled to an AC power supply unit adapted to induce current into the coil assembly to generate a magnetic field.

[0050] Alternatively, the sensor device's measuring head contact detection circuit is configured to detect contact between the measuring head and the second polishing disc as the first and second polishing discs are moved toward each other.

[0051] Alternatively, the measuring head contact detection circuit is configured to detect mechanical vibrations and / or acoustic energy changes and / or temperature changes and / or current changes of the induced current associated with the contact.

[0052] Alternatively, the first and second grinding discs rotate in opposite directions (about the axis of rotation) to provide a pulping effect between the first and second grinding surfaces and to provide mechanical grinding of cellulose fibers for making pulp.

[0053] Alternatively, the first grinding disc is stationary, while the second grinding disc rotates about a rotation axis to provide a pulping effect between the first and second grinding surfaces and to provide mechanical grinding of cellulose fibers for pulp production.

[0054] This objective, or at least one of the objectives, has been achieved by a method for calibrating a sensor device comprising a transducer adapted to generate a magnetic field. The sensor device is configured to measure the pulping gap between a first and a second grinding disc of a fine grinding mill apparatus and is configured to be mounted in the first grinding disc. The sensor device includes magnetic poles, a coil assembly, and a measuring head configured to be positioned in a calibration position relative to the second grinding disc for calibration of the sensor device. The measuring head includes an outer end made of a non-magnetic material configured to abut against the second grinding disc in a calibration sequence. The method comprises the steps of: initiating a calibration sequence; inducing a current into the coil assembly to generate a magnetic field around the magnetic poles; rotating the first and second grinding discs about a rotation axis and moving the first and / or second grinding discs axially toward each other; and abutting the measuring head against the second grinding disc for calibrating the sensor device.

[0055] Alternatively, the step of bringing the measuring head abutting against the second fine grinding disc for calibrating the sensor device can be performed by bringing the measuring head abutting against the second grinding surface for calibrating the sensor device.

[0056] Alternatively, the method includes the following further steps: measuring the change in the magnetic field around the magnetic pole generated by the transducer; and converting the change in the magnetic field into an electrical signal based on the change in the distance between the measuring head and the second fine grinding disc.

[0057] Alternatively, the step of measuring the change in the magnetic field around the magnetic pole generated by the transducer can be performed by a gap measurement conversion circuit coupled to the sensor device, which is configured to convert the change in the magnetic field into an electrical signal based on the change in the gap between the measuring head and the second fine grinding disc (or the second grinding surface).

[0058] Alternatively, the method includes the further step of detecting the contact between the measuring head and the second fine grinding disc and / or the second grinding surface.

[0059] Alternatively, the method step of bringing the measuring head abutting against the second polishing disc for calibrating the sensor device provides a first distance value between the first and second polishing surfaces, which is recorded by a measurement conversion circuit.

[0060] Alternatively, the method further includes the following step: moving at least the first fine grinding disc along the axis of rotation according to the second distance value to achieve an effective pulping gap value.

[0061] This is achieved by abrading the first and second grinding surfaces, so that the first plane of the first grinding surface becomes parallel to the second plane of the second grinding surface (making the first grinding surface parallel to the second grinding surface), but still achieving effective measurement of the pulping gap.

[0062] In this way, the magnetic poles will not be worn down, but will retain their initial length, thus providing a reliable magnetic field around the poles and achieving the correct calibration sequence.

[0063] In this way, incorrect electrical signals can be avoided, and the gap measurement conversion circuit works effectively because the original length of the magnetic poles is maintained.

[0064] Alternatively, the sensor device is configured to be calibrated by moving the magnetic poles axially toward the second grinding surface until the measuring head abuts the second grinding surface of the second fine grinding disc.

[0065] Alternatively, the method includes the steps of providing a sensor device and installing the sensor device in a fine grinding mill.

[0066] Alternatively, the gap measurement conversion circuit is coupled to the measuring head abutment detection circuit to provide a calibration value (e.g., zero), i.e., the sensor device is zeroed.

[0067] Alternatively, the sensor device includes a gap measurement conversion circuit and / or is configured to be coupled to the gap measurement conversion circuit, which is configured to convert changes in magnetic field and / or magnetoresistance and / or current and / or voltage based on changes in the distance between the measuring head and the second grinding surface.

[0068] Alternatively, for sensor device calibration, the first and second grinding discs are moved axially toward each other until the first and second grinding surfaces are in complete or partial contact with each other, and / or the measuring head is in complete or partial contact with the second grinding surface, wherein the sensor device is zeroed.

[0069] This is achieved by wearing down the first set of grinding sections and the second set of grinding sections of the corresponding grinding surfaces, so that the first plane of the first grinding surface will be parallel to the second plane of the second grinding surface, making the first grinding surface parallel to the second grinding surface.

[0070] In this way, the magnetic poles of the sensor device will remain at their full length, provided that the gap measurement conversion circuit converts the current-related value into the correct pulping gap value.

[0071] In this way, the magnetic poles will not be worn down, but will retain their initial length, thereby providing a magnetic field around the poles, which is determined by the induced current entering the coil device.

[0072] Alternatively, the outer end of the measuring head, made of a non-magnetic material, is configured to be worn down until the first grinding surface is parallel to the second grinding surface.

[0073] Alternatively, the magnetic pole includes an inner end and an outer end that define the initial length of the magnetic pole.

[0074] Alternatively, the inner end faces away from the second polishing disc, and the outer end faces the second polishing disc.

[0075] In this way, misleading electrical values ​​are avoided, and the gap measurement conversion circuit will operate with the correct electrical values ​​related to the full length of the magnetic pole.

[0076] Alternatively, the detection circuit is configured to detect mechanical vibrations and / or acoustic energy changes and / or temperature changes and / or current changes of the induced current associated with the contact.

[0077] The objective, or at least one of the objectives, has been achieved by a fine grinding mill apparatus including a sensor device according to claim 1, wherein the fine grinding mill apparatus further includes a fine grinding disc driver, a gap measurement conversion circuit, and a control circuit configured to control the fine grinding disc driver according to a first distance value recorded by the measurement conversion circuit and subsequently according to a second distance value, so as to move the first fine grinding disc and / or the second fine grinding disc along a rotation axis.

[0078] This objective, or at least one of the objectives, has been achieved by a data medium storage program suitable for calibrating a sensor device, wherein the data medium storage program includes program code stored on a medium, which is readable by a computer, for causing a control circuit to perform the following method steps: initiating a calibration sequence; inducing current into a coil assembly to generate a magnetic field around a magnetic pole; rotating a first and / or a second grinding disc about a rotation axis and moving the first and / or second grinding discs axially toward each other; and bringing a measuring head abutting against the second grinding disc for calibrating the sensor device.

[0079] The objective, or at least one of the objectives, has been achieved by a data medium storage program product comprising program code stored on a medium that is readable on a computer for performing the required method steps when the data medium storage program is run on a control circuit. Attached Figure Description

[0080] The invention will now be described by way of example with reference to the accompanying drawings, in which:

[0081] Figure 1 The illustration shows a sensor device according to the first example;

[0082] Figures 2a to 2b The illustration shows a sensor device according to the second example;

[0083] Figures 3a to 3b The illustration shows a sensor device according to the third example;

[0084] Figures 4a to 4b The illustration shows a sensor device according to the fourth example;

[0085] Figures 5a to 5b The diagram illustrates an exemplary method for calibrating a sensor device according to other examples; and

[0086] Figure 6 The diagram illustrates the control circuit of an exemplary sensor device for a fine grinding mill. Detailed Implementation

[0087] In the following description, exemplary embodiments of the present invention will be illustrated with reference to the accompanying drawings, wherein some less important details may be omitted from the drawings for clarity and to facilitate understanding of the invention.

[0088] Figure 1A first example of a magnetically type sensor 1 operating based on the principle of magnetoresistive force is shown. Sensor 1 is installed in a refining mill apparatus 9 provided for pulp production. Sensor 1 is configured to measure the beating gap G between a first grinding surface 4 of a first refining disc 5 and a second grinding surface 6 of a second refining disc 7. The first and second refining discs 5 and 7 rotate in opposite directions about a rotation axis X to induce a beating effect between the first grinding surface 4 and the second grinding surface 6, and to provide mechanical abrasion for supplying cellulose fibers 8 for pulp production.

[0089] Sensor 1 includes a transducer 3 adapted to generate a magnetic field. Transducer 3 includes a magnetic pole 13 and a coil assembly 15. The coil assembly 15 is applied around the magnetic pole 13 and coupled to an alternating current supply unit AC, which is adapted to induce current into the coil assembly 15 for generating the magnetic field.

[0090] Sensor 1 is mounted in a first polishing disc 5 and includes a measuring head 11' configured to be positioned in a calibration position relative to a second polishing disc 7 for calibration of sensor device 1. The measuring head 11' forms part of a sleeve assembly 14 in which magnetic poles 13 are housed. The sleeve assembly 14 includes an outer end portion 10' comprising a non-magnetic material configured to abut against a second grinding surface 6 of the second polishing disc 7 for the calibration sequence. Thus, the non-magnetic material is configured to abut against and be positioned against the second polishing disc for the calibration sequence.

[0091] Sensor 1 is coupled to gap measurement conversion circuit 19, which is configured to convert changes in magnetic field into electrical signals based on changes in the pulping gap G between the measuring head 11' and the second grinding surface 6 of the second fine grinding disc 7.

[0092] The first polishing disc 5 is adapted to move toward and away from each other along the rotation axis X in direction 18. A gap measurement conversion circuit 19 is coupled to a polishing disc driver (not shown), which is configured to move at least the first polishing disc 5 toward and / or away from the second polishing disc 7 along the rotation axis X for adjusting the pulping gap G. The gap measurement conversion circuit 19 is also coupled to a polishing disc position sensor (not shown) for recording the relative positions of the corresponding first and second polishing discs 5 and 7.

[0093] Alternatively, the gap measurement conversion circuit 19 is coupled to the control circuit 130, which is configured to control the polishing disc driver to move the first polishing disc 5 and / or the second polishing disc 7 along the rotation axis X.

[0094] The outer end portion 21 of the magnetic pole 13 contains magnetic material but not non-magnetic material. This magnetic pole is contained within a sleeve device 14, which includes an outer end portion 10' of non-magnetic material configured to abut against the second grinding surface 6 of the second grinding disc 7. A gap measurement conversion circuit 19 is configured to convert a first magnetic field value into a first electrical signal, which is related to a first distance value set between the first grinding surface 4 and the second grinding surface 6. Furthermore, the gap measurement conversion circuit 19 is configured to convert a second magnetic field value into a second electrical signal, which is related to a second distance value set between the first grinding surface 4 and the second grinding surface 6.

[0095] Figures 2a to 2b The figure illustrates a sensor 1 according to the second example. Sensor 1 includes a transducer 3 adapted to generate a magnetic field MF. Sensor 1 is configured to measure the pulping gap G (see figure 5) between the first polishing disc 5 and the second polishing disc 7. Figure 2b (See Figure 2d). The sensor 1 includes a magnetic pole 13, a coil assembly 15, and a measuring head 11” of the magnetic pole 13, which is configured to be set in a calibration position relative to the second fine grinding disc 7 for calibration of the sensor 1.

[0096] Figures 3a to 3b The diagram shows... Figures 2a to 2b The sensor 1 in the example or according to the third example.

[0097] Sensor 1 is configured to measure the pulping gap G between the first grinding surface 4 of the first fine grinding disc 5 and the second grinding surface 6 of the second fine grinding disc (see...). Figures 2b to 3b The sensor 1 includes a magnetic pole 13, a coil assembly 15, and a sleeve assembly 14 with a measuring head 11' comprising an outer end 10' made of a non-magnetic material. The measuring head 11' is configured to abut against a second grinding surface 6 for calibration of the sensor 1. The outer end 10' of the sleeve assembly 14 is configured to be positioned in a calibration position relative to a second fine grinding disc 7 for calibration of the sensor 1. Therefore, the outer end 10' is made of a non-magnetic material configured to abut against and be positioned against the second fine grinding disc 7 in the calibration sequence.

[0098] like Figure 2a As shown, the measuring head 11' is positioned to abut against the second grinding disc 7 and provides a first distance value d1 between the first grinding surface 4 and the second grinding surface 6. The first distance value d1 is recorded as a calibration value by a measurement conversion circuit (not shown) of a control circuit (not shown).

[0099] The first distance value d1 refers to the distance by which the non-magnetic outer end 10' of the sleeve device 14 protrudes from the first grinding surface 4 and in a direction transverse to the first grinding surface 4. The first distance value d1 can be 0.5 / 0.5 mm, or any other suitable distance.

[0100] exist Figure 2b The diagram shows that the control circuit has commanded the first grinding disc 5 to move along the rotation axis (not shown) according to the second distance value d2 to achieve an effective pulping gap G distance value. The pulping gap G distance value can be 5 mm, or any other suitable distance between the first grinding surface 4 and the second grinding surface 6. If the first distance value d1 is 0.5 / 0.5 mm, the second distance value d2 can be 4.5 / 4.5 mm to achieve an effective pulping gap distance value of 5 mm.

[0101] like Figure 3a As shown, the pulping gap G distance value naturally undergoes a change (e.g., due to wear of the grinding surface) to become a third distance value d3, which is different from the effective pulping gap distance value. The sensor 1 records and converts the change of the magnetic field MF of the third magnetic field value according to the third distance value d3.

[0102] like Figure 3b As shown, the gap measurement conversion circuit records the third distance value d3 and the control circuit enables the fine grinding disc driver (not shown) to move the first fine grinding disc 5 and / or the second fine grinding disc 7 toward each other to adjust the third distance value d3, thereby achieving an effective pulping gap G distance value, that is, adjusting the pulping gap G 41 to the second distance value d2, which is effective for optimal grinding.

[0103] Figures 4a to 4b The illustration shows sensor 1 of the fine grinding mill apparatus 9 according to the fourth example. Figure 4a A sensor including a transducer 3 is shown, which is coupled to an AC source and adapted to generate a magnetic field. The sensor 1 is configured to measure the pulping gap G between a first polishing disc 5 and a second polishing disc 7. The sensor 1 includes a magnetic pole 13, a coil assembly 15, and a sleeve assembly 14 with a measuring head 11' including an outer end 10' made of a non-magnetic material, the measuring head 11' being configured to abut against the second polishing disc 7 for calibration of the sensor 1. Therefore, the outer end 10' of the sleeve assembly 14 is configured to be positioned in a calibration position relative to the second polishing disc 7 for calibration of the sensor 1.

[0104] The sensor device 1 may include a measuring head contact detection circuit 23, which is configured to detect contact between the measuring head 11' and the second grinding disc 7 when the first grinding disc 5 and the second grinding disc 7 move toward each other.

[0105] The non-magnetic outer end 10' can protrude from the first fine grinding disc 5 at a known distance recorded by the gap measurement conversion circuit 19 of the control circuit 130.

[0106] The measuring head abutting the detection circuit 23 can be configured to detect and Figure 4bThe mechanical vibration and / or acoustic energy change and / or temperature change and / or current change of the induced current shown are related to the contact.

[0107] Figure 5a An exemplary method for calibrating a sensor device is illustrated. The sensor device includes a transducer adapted to generate a magnetic field. The sensor device is configured to measure the pulping gap between a first and a second grinding disc of a fine grinding mill apparatus and is configured to be mounted in the first grinding disc. The sensor device includes magnetic poles, a coil assembly, and a measuring head configured to be positioned in a calibration position relative to the second grinding disc for calibration of the sensor device. The measuring head includes an outer end portion made of a non-magnetic material configured to abut against and be positioned against the second grinding disc in the calibration sequence.

[0108] The method includes a first step 1001 to begin the method. A second step 1002 demonstrates the performance of the method. A third step 1003 includes stopping the method.

[0109] The second step 1002 may include: initiating a calibration sequence; inducing current into the coil assembly to generate a magnetic field around the magnetic poles; rotating the first and / or second grinding discs about a rotation axis and moving the first and / or second grinding discs axially toward each other; and bringing the measuring head into contact with the second grinding disc for calibrating the sensor device.

[0110] Figure 5b An exemplary method for calibrating a sensor device is illustrated. First step 2001 initiates the method. Second step 2002 includes measuring the change in a magnetic field around a magnetic pole generated by a transducer. Third step 2003 includes converting the change in the magnetic field into an electrical signal based on a change in the distance between a measuring head and a second polishing disc. Fourth step 2004 includes detecting contact between the measuring head and the second polishing disc and / or the second grinding surface. Fifth step 2005 includes bringing the measuring head into contact with the second polishing disc for calibration of the sensor device to provide a first distance value between the first and second grinding surfaces, which is recorded by a measurement conversion circuit. Sixth step 2006 includes the step of moving at least the first polishing disc along a rotation axis according to a second distance value to achieve an effective pulping gap value. Seventh step 2007 includes stopping the method.

[0111] Figure 6 The diagram illustrates a control circuit 130 for an exemplary sensor device 1 of a fine grinding mill apparatus 9. The control circuit 130 is coupled to the sensor device 1. The control circuit 130 is configured to control the fine grinding disc driver of the fine grinding mill apparatus 9 based on a first distance value recorded by a measurement conversion circuit of the sensor device 1 and subsequently based on a second distance value, to move the first and / or second fine grinding discs along a rotational axis.

[0112] The control circuit 130 includes a computer. The control circuit 130 includes a non-volatile memory NVM 620, which is a computer memory that can retain stored information even when the computer is not powered on.

[0113] The control circuit 130 also includes a processing unit 610 and a read / write memory 650. The NVM 620 includes a first storage unit 630. A computer program (which can be any type of computer program applicable to any operational data) is stored in the first storage unit 630 for controlling the functionality of the control circuit 130. Furthermore, the control circuit 130 includes a bus controller (not shown) and a serial communication interface (not shown) providing a physical interface through which information is transmitted separately in both directions.

[0114] The control circuit 130 may include any suitable type of I / O module (not shown) that provides input / output signal transmission, and an A / D converter (not shown) for converting continuously changing signals from the sensor device 1 and from the measuring head contact detection circuit 23, as well as other operational data, into binary code suitable for a computer.

[0115] Other operational data may include the actual load on the grinding disc, the rotational speed of the grinding disc, and the temperature of the grinding surface.

[0116] The control circuit 130 also includes an input / output unit (not shown) for adjusting the time and date. The control circuit 130 includes an event counter (not shown) for counting the number of event multiples occurring from independent events during the operation of the fine grinding mill equipment 9.

[0117] In addition, the control circuit 130 includes an interrupt unit (not shown) associated with a computer for providing multitasking performance and real-time calculations to automatically detect the pulping gap between the first grinding surface and the second grinding surface.

[0118] The NVM 620 also includes a second storage unit 640 for external sensor inspection of the sensor device 1.

[0119] The data medium storage program P may include program routines for automatically adjusting the movement of the fine grinding disc along the axis of rotation based on the detected pulping gap and / or automatically calibrating the sensor device by means of the control circuit 130.

[0120] The data medium storage program P includes program code stored on the medium, which is readable on a computer, for causing the control circuit 130 to perform a method of setting the measuring head relative to the second fine grinding disc 7 in a calibration position, thereby calibrating the sensor device 1.

[0121] The data medium storage program P can also be stored in a separate memory 660 and / or in a read / write memory 650. In this embodiment, the data medium storage program P is stored in an executable or compressed data format.

[0122] It should be understood that when the processing unit 610 is described as performing a specific function, it means that the processing unit 610 can execute a specific part of a program stored in a separate memory 660 or a specific part of a program stored in read / write memory 650.

[0123] Processing unit 610 is associated with data port 999 for communication via a first data bus 615. Non-volatile memory (NVM) 620 is adapted to communicate with processing unit 610 via a second data bus 612. Separate memory 660 is adapted to communicate with processing unit 610 via a third data bus 611. Read / write memory 650 is adapted to communicate with processing unit 610 via a fourth data bus 614. Data port 999 is preferably connected to the data link of sensor device 1. When data is received by data port 999, the data is temporarily stored in second storage unit 640.

[0124] After the received data is temporarily stored, the processing unit 610 will prepare to execute the program code according to the above method.

[0125] Preferably, the signal (received by data port 999) includes information about the operating status of sensor device 1. The signal may also include information about current and previous pulping gap measurements and adjustments to the pulping gap over time.

[0126] The signal received at data port 999 can be used by control circuit 130 for controlling and monitoring the automatic calibration of sensor device 1.

[0127] Information and data can be manually fed to the control unit via a suitable communication device, such as a computer monitor or touch screen.

[0128] This method can also be partially executed by control circuitry 130 via processing unit 610, which runs a data medium storage program P stored in a separate memory 660 or read / write memory 650. When control circuitry 130 runs data medium storage program P, the appropriate method steps disclosed herein are performed.

[0129] Of course, the present invention is not limited in any way to the preferred embodiments described above, but many possible modifications or combinations of the embodiments described herein should be apparent to those skilled in the art without departing from the basic concept of the invention as defined in the appended claims.

Claims

1. A sensor device (1) comprising a transducer (3) adapted to generate a magnetic field (MF), the sensor device (1) being configured to measure the pulping gap (G) between a first grinding disc (5) and a second grinding disc (7) of a grinding mill apparatus (9), and configured to be mounted in the first grinding disc (5), the sensor device (1) comprising a magnetic pole (13), a coil assembly (15), and a measuring head (11'), the measuring head (11') being configured to be positioned in a calibration position relative to the second grinding disc (7) for calibration of the sensor device (1), the sensor device (1) being coupled to a gap measurement conversion circuit (19), the coil assembly (15) being applied around the magnetic pole (13) and coupled to an alternating current supply unit (AC), characterized in that, The measuring head (11') forms part of a sleeve device (14), the magnetic pole (13) is housed in the sleeve device (14), the coil assembly (15) is arranged around the magnetic pole (13), the sleeve device (14) includes an outer end (10'), the outer end (10') includes a non-magnetic material configured to abut against the second polishing disc (7), the non-magnetic material being configured to abut against the second polishing disc (7) in a calibration sequence, wherein the non-magnetic outer end (10') protrudes from the first polishing disc (5) at a known distance recorded by the gap measurement conversion circuit (19) of the control circuit (130).

2. The sensor device (1) according to claim 1, wherein, The non-magnetic sleeve end of the sleeve device (14) forms a sleeve end surface facing the second grinding surface of the second fine grinding disc (7).

3. The sensor device (1) according to claim 2, wherein, The gap measurement conversion circuit (19) is configured to convert the change in the magnetic field (MF) into an electrical signal based on the change in the pulping gap (G) between the measuring head (11') and the second fine grinding disc (7).

4. The sensor device (1) according to claim 3, wherein, The alternating current supply unit (AC) is adapted to induce current into the coil assembly (15) to generate the magnetic field (MF).

5. The sensor device (1) according to claim 4, wherein, The measuring head contact detection circuit (23) of the sensor device (1) is configured to detect the contact of the measuring head (11') with the second grinding disc (7) when the first grinding disc (5) and the second grinding disc (7) move toward each other.

6. The sensor device (1) according to claim 5, wherein, The measuring head contact detection circuit (23) is configured to detect mechanical vibration and / or acoustic energy changes and / or temperature changes and / or induced current changes related to contact.

7. A method for calibrating a sensor device (1), the sensor device (1) comprising a transducer (3) adapted to generate a magnetic field (MF), the sensor device (1) configured to measure the pulping gap (G) between a first grinding disc (5) and a second grinding disc (7) of a grinding mill apparatus (9), and configured to be mounted in the first grinding disc (5), the sensor device (1) comprising a magnetic pole (13), a coil assembly (15) and a measuring head (11'), the measuring head (11') configured to be set in a calibration position relative to the second grinding disc (7) for calibration of the sensor device (1), the sensor device (1) coupled to a gap measurement conversion circuit (19), the coil assembly (15) being applied around the magnetic pole (13) and coupled to an alternating current supply unit (AC), characterized in that, The measuring head (11') forms part of a sleeve device (14), the magnetic pole (13) is housed in the sleeve device (14), the coil assembly (15) is arranged around the magnetic pole (13), the sleeve device (14) includes an outer end (10'), the outer end (10') includes a non-magnetic material configured to abut against the second polishing disc (7), the non-magnetic material being configured to abut against the second polishing disc (7) in a calibration sequence, wherein the non-magnetic outer end (10') protrudes from the first polishing disc (5) at a known distance recorded by the gap measurement conversion circuit (19) of the control circuit (130), the method comprising the following steps: - Begin the calibration sequence; - Current is induced into the coil assembly (15) to generate the magnetic field (MF) around the magnetic pole (13). - Rotate the first polishing disc (5) and the second polishing disc (7) about the rotation axis (X), and move the first polishing disc (5) and the second polishing disc (7) axially toward each other; and - The measuring head (11') is brought into contact with the second fine grinding disc (7) for calibrating the sensor device (1).

8. The method according to claim 7, further comprising the following steps: - Measure the change in the magnetic field around the magnetic pole (13) generated by the transducer (3); - The change in the magnetic field is converted into an electrical signal based on the change in the distance between the measuring head (11') and the second fine grinding disc (7).

9. The method according to claim 8, wherein the method comprises the following further steps: - Detect the contact between the measuring head (11') and the second fine grinding disc (7) and / or the second grinding surface (31).

10. The method of claim 9, wherein the method step of bringing the measuring head (11') abutting against the second fine grinding disc (7) for calibrating the sensor device (1) provides a first distance value between the first grinding surface and the second grinding surface, the first distance value being recorded by the gap measurement conversion circuit.

11. The method of claim 10, wherein the method comprises the following further steps: - Based on the second distance value, at least the first fine grinding disc is moved along the rotation axis to achieve an effective pulping gap value.

12. A fine grinding mill apparatus (9) including the sensor device (1) according to claim 1, the fine grinding mill apparatus (9) further including a fine grinding disc driver, the gap measurement conversion circuit and a control circuit (130), the control circuit (130) being configured to control the fine grinding disc driver according to a first distance value recorded by the gap measurement conversion circuit and subsequently according to a second distance value, so as to move the first fine grinding disc and / or the second fine grinding disc along a rotation axis.

13. A data medium storage program product, the data medium storage program product comprising a data medium storage program (P), the data medium storage program (P) comprising program code stored on a medium, the program code being readable on a computer, the data medium storage program (P) executing the method steps according to any one of claims 7 to 11 when run on a control circuit.

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