A BEATING GAP SENSOR DEVICE FOR A REFINER APPARATUS AND CALIBRATION METHOD

Abstract

The present invention concerns a sensor device (1) comprising a transducer (3) adapted to generate a magnetic field (MF), the sensor device (1) is configured to measure a beating gap (G) between a first (5) and a second (7) refining disc of a refiner apparatus (9) and is configured to be mounted in the first refining disc (5), the sensor device (1) comprises a magnetic pole (13), a coil assembly (15) and a measuring head (11′), which measuring head (11′) is configured to be set in 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 present invention also concerns a method of calibration of said sensor device (1).

Description

Claims

1. A sensor device comprising a transducer, which is configured to generate a magnetic field, wherein the sensor device is configured to measure a beating gap between a first and a second refining disc of a refiner apparatus and is configured to be mounted in the first refining disc, wherein the sensor device comprises a magnetic pole, a coil assembly and a measuring head, which measuring head is configured to be set in a calibration position relative to the second refining disc for calibration of the sensor device, and wherein the measuring head comprises an outer end made of a non-magnetic material configured to be positioned in abutment with the second refining disc in a calibration sequence.

2-15. (canceled)

16. The sensor device according to claim 1, wherein the measuring head constitutes a portion of a sleeve arrangement in which the magnetic pole is accommodated, wherein the sleeve arrangement comprises the outer end comprising the non-magnetic material configured to abut the second refining disc.

17. The sensor device according to claim 16, wherein a non-magnetic sleeve end of the sleeve arrangement forms a sleeve end surface facing a second grinding surface of the second refining disc.

18. The sensor device according to claim 1, wherein the sensor device is coupled to a gap measurement converting circuitry, configured to convert variation of the magnetic field to electrical signals depending upon variation of the beating gap between the measuring head and the second refining disc.

19. The sensor device according to claim 1, wherein the coil assembly is applied around the magnetic pole and is coupled to an AC supply unit configured to induce an electric current into the coil assembly for generating the magnetic field.

20. The sensor device according to claim 1, wherein a measuring head abutment detecting circuitry of the sensor device is configured to detect abutment of the measuring head abutting the second refining disc, when moving the first and the second refining disc toward each other.

21. The sensor device according to claim 20, wherein the measuring head abutment detecting circuitry is configured to detect mechanical vibrations and/or acoustic energy changes and/or temperature changes and/or current alternation of said induced electric current, related to said abutment.

22. A method of calibration of a sensor device comprising a transducer, which is configured to generate a magnetic field, wherein the sensor device is configured to measure a beating gap between a first and a second refining disc of a refiner apparatus and is configured to be mounted in the first refining disc, wherein the sensor device comprises a magnetic pole, a coil assembly and a measuring head, which measuring head is configured to be set in a calibration position relative to the second refining disc for calibration of the sensor device, and wherein the measuring head comprises an outer end made of a non-magnetic material configured to be positioned in abutment with the second refining disc in a calibration sequence, the method comprising: starting a calibration sequence;inducing an electric current into the coil assembly to generate a magnetic field around the magnetic pole;rotating the first and/or the second refiner disc about a rotary axis and moving them axially toward each other; andbringing the measuring head into abutment with the second refining disc for calibrating the sensor device.

23. The method according to claim 22, further comprising: measuring the variation of the magnetic field around the magnetic pole generated by the transducer; andconverting the variation of the magnetic field to electric signals depending upon variation of the distance between the measuring head and the second refining disc.

24. The method according to claim 22, further comprising: detecting abutment of the measuring head abutting the second refining disc and/or the second grinding surface.

25. The method according to claim 22, wherein the step of bringing the measuring head into abutment with the second refining disc for calibrating the sensor device provides a first distance value between the first and second grinding surface, which first distance value is registered by the measurement converting circuitry.

26. The method according to claim 25, further comprising: moving at least the first refining disc along the rotary axis in accordance with a second distance value for reaching an efficient beating gap value.

27. A refiner apparatus comprising a sensor device according to claim 1, wherein the refiner apparatus further comprises a refining disc driver, a gap measurement converting circuitry and a control circuitry configured to control the refining disc driver to move the first and/or second refining disc along a rotary axis in accordance with a first distance value registered by the measurement converting circuitry and subsequently in accordance with a second distance value.

28. A data medium storing program configured to calibrate the sensor device of the refiner apparatus according to claim 27, wherein said data medium storing program comprises a program code stored on a medium, which is readable on a computer, for causing the control circuitry to perform the method steps of: starting a calibration sequence;inducing an electric current into the coil assembly to generate the magnetic field around the magnetic pole;rotating the first and/or the second refiner disc about a rotary axis and moving them axially toward each other; andbringing the measuring head into abutment with the second refining disc for calibrating the sensor device.

29. A data medium storing program product comprising a program code stored on a medium, which is readable on a computer, for performing the method steps according to claim 22, when a data medium storing program is run on the control circuitry.