Vibration measuring device

Abstract

The invention relates to a device and a method for fiber treatment. The device has a housing composed of multiple parts, in which at least one first treatment tool (1, 3) and at least one second treatment tool (2, 4) are arranged. The treatment tools (1, 2, 3, 4) have a rotationally symmetrical shape and are arranged coaxially relative to one another and rotate relative to one another about a common axis (5). Each two treatment tools (1, 2, 3, 4) define the boundaries of a treatment gap (11, 12) through which a fiber material flows in the radial direction. Two housing parts (7, 8) each carrying at least one treatment tool (1, 2, 3, 4) are coupled to one another by means of a joint (9) that can be rotated about a joint axis (13). Here, the contact between the two treatment tools (1, 2, 3, 4) is reliably identified by at least one sensor (6) for detecting vibrations of the device, preferably an externally arranged sensor (6).

Description

[0001] This invention relates to an apparatus for processing fibrous materials, incorporating a sensor for detecting vibration. The apparatus has a housing composed of multiple components. The housing includes a cover. The apparatus also includes a plurality of fiber processing tools, which are arranged at intervals to form at least one processing gap through mutually facing processing surfaces and are rotatably supported relative to each other. At least one processing tool is axially movable to define the width of the at least one processing gap between the mutually facing processing surfaces. At least one processing tool is carried by a housing component.

[0002] Typically, the processing tools have a rotationally symmetrical shape and are arranged coaxially with each other. Two processing tools define the boundary of a processing gap through which the fibrous material flows radially, and each processing tool has a processing profile pointing towards the processing gap. If multiple processing gaps are provided, at least one processing tool may be specified to be axially floatingly supported.

[0003] The present invention also relates to a method for minimizing wear in an apparatus for processing fibrous materials, wherein the apparatus has a housing composed of multiple components, in which at least one first processing tool and at least one second processing tool are arranged, the processing tools having a rotationally symmetrical shape, being arranged coaxially relative to each other, and rotating relative to each other about a common axis, each pair of processing tools defining the boundary of a processing gap through which the fibrous material flows radially, and each processing tool having a processing profile pointing towards the processing gap, wherein at least one processing tool is axially floatingly supported, two housing components each carrying at least one processing tool are coupled to each other by a hinge rotatable about a hinge axis, and the apparatus is equipped with at least one sensor.

[0004] A refining mill for processing fiber suspensions used in papermaking is known from patent document US 2007 / 0125891 A1. A vibration sensor is installed in the refining mill to identify contact with the processing tool. The sensor is arranged inside the refining mill on a fixed carrier of the processing tool. Axial vibration motion is detected by the sensor. Contact with the processing tool can be inferred based on the axial vibration motion. Alternatively, two vibration sensors can be provided, each mounted on a fixed carrier of the processing tool.

[0005] A fine grinding mill and a method for fixing or removing the fine grinding discs are known from document EP 792 689 B1. The fine grinding mill has a grinding chamber. The grinding chamber includes a main section. The main section is closed by a cover. The cover is connected to the main section by a hinge and can be opened, wherein, in the open position, the cover is supported by the hinge.

[0006] Such equipment, such as grinding mills, dispersers, and de-fiber machines, allows for the mechanical processing of fibrous materials, even though the processing tools, which move relative to each other, do not come into contact; rather, they pass each other at very short distances. The intensity of the processing depends on both the width of the gap between the surfaces of the processing tools and the concentration of the fibrous material. As the intensity of the processing increases, the processing tools also wear down. For example, the aforementioned types of equipment are used to improve the quality of fibrous materials obtained from pulp, TMP, or waste paper.

[0007] If wear causes a reduction in the height of the processing profile of the processing tool, the resulting increased processing clearance leads to a decrease in idling or pumping power. With the total power remaining constant, this simultaneously increases the specific power of the equipment related to the required processing intensity, thus causing the processing to be too intense, particularly the abrasion of fibers.

[0008] If the gap is too small, there is a risk of excessive current consumption and contact with the handling tools.

[0009] It has long been known to grind pulp fibers, namely primary and secondary fiber materials, in order to achieve desired properties, particularly in terms of strength, porosity, shape and surface, in the resulting fiber web.

[0010] In the fine grinding mill used here, due to relatively rapid wear, the grinding surface is formed by replaceable grinding sleeves that are screwed onto the corresponding base plate. In order to achieve the desired fiber properties, especially the Schopper-Riegler value, the grinding sleeve must be adapted in an optimal manner to the fiber material to be processed, in addition to providing ideal fiber treatment, it also serves to prevent excessive wear of the grinding sleeve.

[0011] The grinding mill can be designed as a disc grinding mill or a cone grinding mill.

[0012] To increase throughput, dual-clearance devices are increasingly being used. Because the rotor is axially floating, the clearance width and wear condition cannot be reliably evaluated. Theoretically, hydraulic balance should produce uniform clearance widths, but in practice, it has been shown that inconsistent clearance widths occur during operation.

[0013] The technical problem to be solved by the present invention is to provide an apparatus and a method that can reduce the high wear of the grinding sleeve caused by contact with the processed surfaces during operation.

[0014] Therefore, the technical problem to be solved by the present invention is to minimize the wear of processing tools in these devices with the simplest possible components. Furthermore, the technical problem to be solved by the present invention is to provide a method by which the wear of processing tools can be minimized.

[0015] The present invention solves the aforementioned technical problem by arranging a sensor for detecting vibrations of the equipment on the equipment housing. Preferably, the sensor is arranged externally on the housing. By arranging it on the housing, the sensor can be easily accessed. This arrangement of the sensor enables simple maintenance, simple replacement, and simple modification.

[0016] To detect vibrations that indicate contact with the processing tool, it is advantageous to place the sensor on the housing component that carries the processing tool.

[0017] It has proven advantageous that the housing component is fixed in place and that the sensor is at least mounted on or within a housing component known as a cover, which can pivot away from the housing component via a hinge.

[0018] To detect increased wear, the sensor should detect vibration acceleration and / or vibration in the range of 4 to 12 kHz.

[0019] For this purpose, a single-axis accelerometer is particularly suitable, preferably oriented parallel to the axis of the device. If the processing surface is flat, the axis is also parallel to the width of the processing gap. If a tapered processing surface is provided, it is advantageous that the axis of the single-axis accelerometer is oriented parallel to the width of the processing gap. In this case, the width of the processing gap is perpendicular to the processing surface. Single-axis accelerometers are readily available and inexpensive for mass production.

[0020] This invention is preferably used in devices having two processing gaps within a housing and two intermediate processing tools fixed to a common, rotating base plate that is axially floating. In principle, this can also be used for delamination or dispersion, in addition to the preferred grinding process.

[0021] If a critical wear condition is identified (the fiber suspension pad in the processing tool contact or processing gap is too small), this condition can be easily overcome if the axial position of at least one processing tool in the housing component is adjustable. This allows for simple suppression of accelerated wear by widening the processing gap.

[0022] In one embodiment, the cover of the housing is provided to be rotatably supported about the hinge axis. In particular, at least two hinges are provided. It has been shown to be advantageous to arrange the sensor on the housing, preferably on the cover, in the region between the hinges. Here, the region between the hinges is defined by a plane extending perpendicular to the hinge axis. If the hinge axis extends perpendicularly, the sensor is arranged in the horizontal region between the hinges.

[0023] In one embodiment, the sensor is positioned on the cover half on the hinge side.

[0024] It has been shown that a position between the hinges parallel to the extension of the processing gap is particularly suitable, wherein the sensor axis is oriented in the direction of the gap width. This allows for the detection, in particular, of vibrations caused by contact with the processing surface of the processing tool.

[0025] It has been shown that it is advantageous to select a location that provides stiffness for the sensor in order to minimize high-frequency interference vibrations.

[0026] In terms of methodology, it is important that, in order to minimize wear, the vibration intensity, particularly the vibration acceleration or the standard deviation of the vibration acceleration, is determined by sensors in the equipment used to process fibrous materials. The determined vibration signal is filtered by a high-pass filter, particularly a high-pass filter of at least 4000 Hz, preferably at least 5000 Hz.

[0027] Vibration is identified when it exceeds a vibration threshold (also known as a vibration peak), specifically the vibration acceleration within a predetermined number of time intervals. If the vibration threshold is exceeded for at least half of the time intervals, a fault is indicated by a signal.

[0028] In one embodiment, the measurement is specified to last for a time interval of at least 2 seconds. In another embodiment, the time intervals are specified to have the same length.

[0029] In order to conceal temporary contact between processing tools caused by operation, contact between two processing tools should only be inferred if at least one vibration peak occurs in at least three of at least five consecutive predetermined time intervals within at least two predetermined time periods.

[0030] It is particularly advantageous to consider at least five successive time intervals. If a vibration peak is identified within three time intervals, the fault is represented by a signal.

[0031] Reliability can be improved when assessing vibration by considering the fundamental vibrations of the equipment's environment. Therefore, it is stipulated that the fundamental values ​​of vibrations caused by operation be learned each time the equipment is started. This can eliminate fundamental vibrations caused by the environment.

[0032] It has been shown that, in order to determine vibration intensity, the standard deviation is continuously determined from the recorded vibration acceleration signal. If the machine operates smoothly under high load, the standard deviation can be lower than the determined vibration acceleration.

[0033] The present invention will be further described below with reference to embodiments.

[0034] In the attached image:

[0035] Figure 1 The image shows a dual-disc fine grinding mill in its open position.

[0036] Figure 2 A side view of a closed grinding mill is shown;

[0037] Figure 3 Another side view of the closed grinding mill is shown;

[0038] Figure 4 A schematic diagram of the cross-section of the slitting and grinding mill is shown.

[0039] Figure 5 A graph showing sensor data and time interval methods;

[0040] Figure 6 A graph showing acceleration data compared to the standard deviation is displayed.

[0041] According to the housing of the equipment used for grinding fiber materials Figure 4 There are two parallel processing gaps 11 and 12 extending perpendicular to the rotation axis 5, which are formed by a non-rotating processing tool 1 and 4 and a flat processing tool 2 and 3 rotating around the axis 5, respectively.

[0042] The annular processing profiles 10 of the processing tools 1, 2, 3, and 4, respectively facing the processing gaps 11 and 12, are formed by abrasive sleeves. These abrasive sleeves have multiple radially extending abrasive strips on the profile side, such that the profile is formed by these abrasive strips and grooves located therebetween.

[0043] The fiber suspension to be ground arrives at this point through the central inlet of the equipment and enters one of the two processing gaps 11 and 12 between the grinding units. The fiber suspension then passes radially outward through the cooperating processing tools 1, 2, 3, and 4 and is collected in the adjacent annular space.

[0044] At least a portion of the fiber suspension treated in this way leaves the annular space through an outlet, while another portion of the fiber suspension may, in some cases, flow back through a section of the trough of the non-rotating treatment tools 1, 4.

[0045] The cross-section of the grinding strip is also called a blade and is generally rectangular, but other shapes also exist. The upper side of these grinding strips, that is, the surface that carries the grinding edge, lies in a radial plane, and these surfaces terminate the corresponding grinding sleeve in the direction of the mating sleeve.

[0046] The grooves extending between the abrasive strips also have a rectangular cross-section and serve as flow channels for the fiber suspension. The groove depths are mostly between 2 mm and 20 mm.

[0047] In the grinding apparatus shown here, the processing tools 2,3 adjacent to the corresponding other processing gaps 11, 12 in the two processing gaps 11, 12 rotate about an axis 5 passing through the center of the processing profile 10. These rotating processing tools 2, 3 are detachably fixed to a common base plate 14 that can move axially on the rotating axis 5 and rotate with it.

[0048] from Figure 2 As can be seen, shaft 5 is driven by drive device 16 coupled through transmission device 15.

[0049] The casing of the device is particularly based on Figure 1 and Figure 3 It consists of a large, fixed housing component 7 supported on a machine base 17 and a smaller, cover-shaped housing component 8 that can pivot away from the housing component 7.

[0050] The two housing components 7 and 8, which respectively carry non-rotating processing tools 1 and 4, are coupled to each other by a hinge 9, which is exemplarily designed as two components and is rotatable about the hinge axis 13.

[0051] The non-rotating processing tool 4 is fixedly connected to the fixed housing component 7, and the other non-rotating processing tool 1 can be moved axially along the rotation axis 5 by the adjustment device 18 to adjust the total width of the two processing gaps 11 and 12.

[0052] Since the base plate 14 is floatingly supported on the shaft 5, its axial position is coordinated with the hydraulic pressure acting in the two processing gaps 11 and 12.

[0053] Therefore, depending on the flow rate and the wear of the two processing gaps 11 and 12, the widths of the processing gaps 11 and 12 may differ, which has a negative impact on the quality of fiber processing and wear.

[0054] Furthermore, the increased friction value of the rotating base plate 14 (and its processing tools 2, 3) when axially floating on the shaft 5 causes the rotor to become uncenterable.

[0055] As a result, there may not be a sufficiently large fiber suspension pad or even contact between the processing tools 1, 2, 3, and 4 in the processing gaps 11 and 12.

[0056] When the processing tools 1, 2, 3, and 4 in the processing gaps 11 and 12 come into contact, the processing surfaces 10 of these processing tools 1, 2, 3, and 4 experience exponential wear during the contact time.

[0057] To prevent this greater wear, vibration of the equipment is monitored by at least one sensor 6. This sensor 6 is designed as a single-axis accelerometer with a piezoelectric measurement principle and is oriented parallel to axis 5.

[0058] As demonstrated here, which is advantageous for reliably identifying critical operating conditions, sensor 6 detects vibrations in the range of 5 kHz to 12 kHz and measures the vibration acceleration thereon.

[0059] In order to take into account the low-frequency fundamental vibrations of the environment when evaluating the signal of sensor 6, at least one additional sensor detects vibrations in the area of ​​transmission device 15.

[0060] To reliably measure vibrations and minimize wear in this device used for handling fibrous materials, at least one sensor 6 is arranged in the housing near the joint 9. This area also has high stiffness due to the high stress.

[0061] like Figure 3 As shown, sensor 6 is located in housing component 8, which can be pivoted away from hinge 9, and is located substantially between the two door hinges of hinge 9, wherein the straight line between sensor 6 and shaft 5 extends substantially perpendicular to hinge axis 13.

[0062] Here, if the sensor 6 of the pivotable housing component 8 knows that the vibration intensity exceeds the previously determined vibration threshold, the critical operating state of the equipment in terms of wear can be inferred, especially the contact of the processing tools 1, 2, 3, 4 in the processing gaps 11, 12.

[0063] exist Figure 5 Vibration signals were recorded. To eliminate erroneous signals, especially those occurring during very brief, temporary contact between processing tools 1, 2, 3, and 4, the equipment's control system infers contact between the two processing tools 1, 2, 3, and 4 only if a predetermined vibration threshold is exceeded at least once in at least three of the five consecutive predetermined time intervals 25. Time intervals with vibration 28 and inconspicuous time intervals are shown. Measurement windows with the corresponding five time intervals are shown, where faulty operation with signal transmission occurs only in the middle measurement window, because only in this measurement window is a minimum number of time intervals with vibration detected.

[0064] Figure 6 The graph shown records the vibration acceleration over the indicated time period and the standard deviation of the vibration acceleration compared to that time period.

[0065] If the equipment's control system identifies a critical operating state for processing tools 1, 2, 3, and 4 through the vibration measurement, the axial position of the non-rotating processing tool 1, carried by the pivotable housing component 8, is adjusted accordingly by the adjustment device 18 to widen the processing gaps 11 and 12.

[0066] This invention is also applicable to conical grinding surfaces, wherein the cone axis coincides with the rotation axis 5, and is also applicable to devices with only one processing gap.

[0067] In summary, the present invention relates to an apparatus and method for fiber processing. The apparatus has a housing composed of multiple components, within which at least one first processing tool (1, 3) and at least one second processing tool (2, 4) are arranged. The processing tools (1, 2, 3, 4) have rotationally symmetrical shapes and are arranged coaxially relative to each other and rotate relative to each other about a common axis (5). Each pair of processing tools (1, 2, 3, 4) defines the boundary of a processing gap (11, 12) through which the fibrous material flows radially. Two housing components (7, 8), each carrying at least one processing tool (1, 2, 3, 4), are coupled to each other by a hinge (9) rotatable about a hinge axis (13). Here, the contact between the two processing tools (1, 2, 3, 4) is reliably detected by at least one sensor (6) arranged on the housing for detecting vibration, preferably an externally arranged sensor (6).

[0068] List of reference numerals in the attached diagram:

[0069]

[0070]

Claims

1. An apparatus (20) for processing fibrous materials, comprising a sensor (6) for detecting vibration and a multi-part housing with a cover (8), and further comprising fiber processing tools (1, 2, 3, 4) arranged within said housing, wherein, The fiber processing tools (1, 2, 3, 4) are arranged at intervals to form processing gaps (11, 12) through processing surfaces (10) facing each other, and the fiber processing tools (1, 2, 3, 4) are rotatably supported relative to each other. At least one processing tool (1) is axially movably supported in the housing for the width of at least one of the processing gaps (11, 12) between the processing surfaces (10) facing each other, wherein at least one housing component carries the fiber processing tool. Its features are, The sensor (6) is arranged on the housing, wherein the housing component (7) is fixed and at least the sensor (6) is mounted on or in a cover (8) that can pivot away from the housing component (7) via a hinge, the sensor (6) being arranged on the housing near the hinge (9), wherein the sensor (6) is designed as a single-axis accelerometer with its axis oriented parallel to the width of the processing gaps (11, 12).

2. The device according to claim 1, wherein, The cover (8) is rotatably supported by at least two hinges (9) about the hinge axis (13). Its features are, The sensor (6) is arranged on the cover (8) in the region between the hinges (9), wherein the region between the hinges (9) is defined by a plane extending perpendicular to the hinge axis (13).

3. The device (20) according to claim 1 or 2, Its features are, The cover is rotatably supported about a vertically extending hinge axis (13).

4. The device (20) according to claim 1 or 2, Its features are, The sensor (6) is arranged on the hinge side of the cover half of the cover (8).

5. The device (20) according to claim 1 or 2, Its features are, A high-pass filter of at least 4000 Hz is provided for signal processing of the sensor (6) signal.

6. The device (20) according to claim 1 or 2, Its features are, The device (20) includes a control device having a memory for storing standard deviation (22), and wherein an evaluation device is provided, and a fault operation (25) is identified by the evaluation device when a predetermined number of time intervals (26) subjected to vibration loads exceed a predetermined length, wherein at least half of the time intervals (28) are subjected to vibration loads.

7. The device (20) according to claim 1 or 2, Its features are, The predetermined length of the predetermined time interval (26) is at least 2 seconds.

8. The device (20) according to claim 1 or 2, Its features are, The lengths of the corresponding observation time intervals (26) are the same.

9. The device (20) according to claim 6, Its features are, At least three of the five time intervals (28) are subjected to vibration loads.

10. A method for identifying faulty operation of a device according to any one of claims 1 to 9, comprising the following steps: - Detect vibration acceleration using a vibration sensor with at least one uniaxial axis. - Filter vibration signals using a high-pass filter. - When a vibration threshold exceeding a predetermined value is detected, the vibration acceleration is determined within a predetermined number of predetermined time intervals. - If the vibration threshold is exceeded for at least half of the continuous time intervals, a fault operation is indicated by a signal.

11. The method according to claim 10, Its features are, The measurement lasts for at least 2 seconds.

12. The method according to claim 10 or 11, Its features are, The determination of the vibration intensity involves continuously calculating the standard deviation from the recorded vibration acceleration signals and using this standard deviation to identify faulty operation.

13. The method according to claim 10 or 11, Its features are, After each startup, the basic values ​​of vibrations caused by the operation are learned in order to eliminate the basic vibrations caused by the environment.

14. The method according to claim 10 or 11, Its features are, When a fault is detected, the axial position of at least one processing tool (1, 2, 3, 4) of the housing component is adjusted to widen at least one processing gap (11, 12).

15. The method according to claim 10, Its features are, If the vibration threshold is exceeded in at least 3 of the 5 time intervals, a fault operation is indicated by a signal.

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