Conveyance roller degradation detector and method for detecting degradation

Abstract

To detect degradation of a conveyance roller before the roller is broken, without stopping a device using the roller, and switch the degraded roller.SOLUTION: The conveyance roller degradation detector includes: an acoustic sensor for detecting an elastic wave generated in a roller; an amplitude measurement unit for measuring the amplitude of a detection signal by the acoustic sensor; and an analysis unit for determining the degree of degradation of the roller from the amplitude. Also, the conveyance roller has a determination unit for predicting the time of switching the conveyance roller on the basis of the result of the analysis by the analysis unit.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a deterioration detection device and a deterioration detection method for a conveying roller.

Background Art

[0002] As an example of a conveying roller device that conveys an object to be conveyed by a conveying roller, there is a roller hearth kiln (RHK). The roller hearth kiln (RHK) is a type of tunnel furnace in which a large number of motor-driven rollers are installed at regular intervals on the floor inside the furnace, and the object to be fired inside the furnace is placed on the rollers and conveyed. It is a continuous firing furnace of this type. For the conveyance of the object to be fired, the rotation speed of the rollers is appropriately set, and these rotation speeds can also be changed depending on the part inside the furnace. The object to be fired is placed on a conveying plate, a sheath, a sagger, etc., and is sent through the furnace at a predetermined speed by the rotation of the rollers, and undergoes a series of temperature increase, firing, and cooling processes continuously.

[0003] During this time, the temperature inside the furnace is constant, and since there is no need to use thermal energy for heating and cooling the furnace body, saggers, etc., the furnace has high thermal efficiency. Generally, the rollers are made of ceramic that requires high heat resistance. Also, by performing precise temperature control in each zone of atmosphere control such as air, N2, O2, N2 + H2, and preheating, firing, and cooling, it is excellent in temperature uniformity, cleanliness, and thermal efficiency. For this reason, the roller hearth kiln (RHK) is used in the manufacture of various fine ceramic molded bodies, the firing of various powder raw materials, the manufacture of positive and negative electrode materials for lithium-ion batteries, electronic components typified by MLCCs, and other applications.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005]

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] During the operation of a roller hearth kiln (RHK), the conveyor roller may break, and it is necessary to detect the deterioration of the conveyor roller. For example, Patent Document 1 discloses a rotational machine abnormality detection device that uses a non-contact acoustic emission sensor such as a laser microphone to detect acoustic emissions propagated in the air and diagnoses that a rotational abnormality has occurred when there is a frequency component equal to or higher than a predetermined threshold value in a predetermined frequency band. However, this device stops the rotation of the rotational machine to be detected and replaces parts when an abnormality is detected.

[0007] Patent Document 2 discloses an abnormality prediction diagnosis device for a valve sliding part that uses an acoustic emission sensor to detect the sliding sound of a valve, obtains the leakage amount, surface roughness, or friction coefficient of the sliding part of the valve from the spectral intensity of the detected sliding sound, and determines a sign of deterioration including whether the function of closing the fluid of the valve and the dynamic function are normal. However, this device performs an abnormality prediction diagnosis while the operation of the facility is stopped during regular inspections.

[0008] On the other hand, a roller hearth kiln (RHK) is used, for example, to manufacture fired products by continuous operation for 24 hours a day, 365 days a year. However, once a roller breaks, the conveyed fired product cannot be conveyed, and the fired product that has fallen into the furnace must be removed. Therefore, the operation must be stopped and the operator must wait for the temperature in the furnace to drop. There is a problem that production cannot be carried out for about two weeks until the operation is restarted after replacement.

[0009] Therefore, it is required to be able to detect the deterioration of the conveyor roller and replace the deteriorated roller before the conveyor roller breaks without stopping the device in which the conveyor roller is used.

Means for Solving the Problems

[0010] (1) The deterioration detection device for a conveying roller according to the present invention is characterized by comprising an acoustic sensor that detects elastic waves generated by the conveying roller, an amplitude measurement unit that measures the amplitude of the detection signal from this acoustic sensor, and an analysis unit that determines the degree of deterioration of the conveying roller from this amplitude. By configuring in this way, it is possible to detect the deterioration of the conveying roller during the operation of a conveying roller device provided with a plurality of conveying rollers.

[0011] (2) The deterioration detection device for a conveying roller according to (1) is characterized by having a determination unit that predicts the replacement timing of the conveying roller based on the analysis result of the analysis unit. By configuring in this way, it is possible to determine the replacement timing of the conveying roller without stopping the operation of the conveying roller device.

[0012] (3) Regarding a device in which a plurality of conveying rollers are installed and the conveying roller can be replaced from outside the device without stopping its operation, the degree of deterioration of the conveying roller is determined by the deterioration detection device for a conveying roller according to (1). By configuring in this way, it is possible to replace the deteriorated conveying roller without stopping the operation of the conveying roller device.

[0013] (4) The deterioration detection method for a conveying roller according to the present invention is characterized by comprising a step of detecting elastic waves generated by the conveying roller with an acoustic sensor, a step of determining the amplitude of the detection signal from this acoustic sensor, and a step of determining the degree of deterioration of the conveying roller from this amplitude. By configuring in this way, it is possible to detect the deterioration of the conveying roller during the operation of a conveying roller device provided with a plurality of conveying rollers.

Advantages of the Invention

[0014] According to the conveyance roller deterioration detection device and the deterioration detection method of the present invention, it is possible to detect the deterioration of the conveyance rollers during the operation of a conveyance roller device including a plurality of conveyance rollers.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0016] Hereinafter, with reference to the drawings, the configuration of a conveyance roller deterioration detection device according to an embodiment of the present invention will be described. FIG. 1 is a schematic view showing the appearance of one side surface of a roller hearth kiln (RHK) as an example of a device to be detected by a conveyance roller deterioration detection device according to an embodiment of the present invention. In FIG. 1, one side wall 3 of the heating furnace 2 of the roller hearth kiln 1 is composed of an upper side wall 31 and a roller part side wall 32.

[0017] Figure 2 is a longitudinal sectional view showing the schematic internal structure of the roller hearth kiln 1 shown in Figure 1. In Figure 2, a large number of rollers 5 are arranged on the pedestal 4, and the rollers 5 are rotated by a drive mechanism (not shown) to convey the saggers 6 placed on the rollers 5 in the direction indicated by the arrow 7. The heating furnace 2 has an elongated shape of, for example, more than 20 meters in the conveying direction of the object to be fired, and is composed of a plurality of zones in which the temperature and atmosphere can be set respectively. It is divided into a heating-up zone, a keep zone, and a cooling zone to fire the powder of the object to be fired filled in the saggers 6.

[0018] As the rollers 5, ceramic rollers are used due to their excellent dimensional accuracy, sufficient strength in the high-temperature range, and excellent corrosion resistance. The rollers 5 are inserted through roller insertion holes provided through the side wall 3 of the heating furnace 2 and assembled to the furnace body. A certain gap is provided between the roller insertion holes and the rollers 5 in consideration of the thermal expansion difference and assembly accuracy with the heat insulating material constituting the side wall 3, and the gap is properly sealed. One end of the roller 5 is attached to the roller part side wall 32 by the roller support part 51. Figure 1 shows one side wall 3 of the heating furnace 2, and the state in which one end of the roller 5 is supported by the roller support part 51 on one roller part side wall 32 is shown, but the other end is also supported by a roller support on the other roller part side wall (not shown) in the same manner.

[0019] The roller 5 can be pulled out from the inside of the heating furnace 2 through the roller insertion hole together with the roller support part 51 and replaced with a new roller. One sagger 6 is placed and supported on a plurality of rollers 5, and in the process of removing one deteriorated roller and inserting a new roller, it does not affect the conveyance of the sagger 6.

[0020] The roller 5 is formed of ceramics having excellent thermal and mechanical properties such as heat resistance, corrosion resistance, and abrasion resistance compared to metals. By the way, the positive electrode material of the lithium ion secondary battery is generally manufactured by mixing a lithium compound as a raw material and compounds such as oxides and hydroxides of nickel, manganese, cobalt, etc. in powder form, putting the mixed powder into the crucible 6, firing it at 700 to 1100 ° C in the heating furnace 2, and then pulverizing it into powder.

[0021] At the beginning of the conveyance of such an object to be fired, the roller 5 has a predetermined wall thickness so as to have sufficient strength for the conveyance of the crucible 6. When the roller 5 is installed in the roller hearth kiln 1 and, for example, the production of the positive electrode material of the lithium ion secondary battery is started, the powder of the lithium compound is heated in the heating furnace 2, lithium vapor is generated, and the ceramics constituting the roller 5 are corroded. Due to the corrosion of the ceramics, the wall thickness of the roller 5 gradually becomes thinner, and the strength of the roller 5 gradually decreases.

[0022] However, during the operation of the roller hearth kiln 1, the wall thickness of the roller 5 in the heating furnace 2 cannot be known, and its strength cannot be directly measured. If the operation is continued until the roller breaks, the operation of the roller hearth kiln has to be stopped for a long time for roller replacement.

[0023] FIG. 3 is a functional block diagram showing a schematic configuration of a deterioration detection device for a conveyance roller according to an embodiment of the present invention. In FIG. 3, an acoustic emission (AE) sensor 101 attached to the roller side wall portion 32 in FIG. 1 captures elastic waves generated from the roller 5 which is an object to be detected. The preamplifier 102 amplifies the output signal of the AE sensor 101. The sensor output signal amplified by the preamplifier 102 has a waveform of amplitude as shown in FIGS. 4(A) and (B).

[0024] Figure 4(A) shows the output signal of the AE sensor 101 when a new roller 5 is installed, and Figure 4(B) shows the output signal of the AE sensor 101 after the roller hearth furnace 1 has been operated for 9 months after installation. In Figure 3, the output of the filter 103 is amplified by the main amplifier 104 and input to the amplitude measurement unit 105. The amplitude measurement unit 105 measures the amplitude of the output signal of the AE sensor 101.

[0025] Figure 5 shows the results of a three-point bending test on one roller 5. The horizontal axis in Figure 5 represents displacement (mm), and the vertical axis represents the test force Ft (N). As shown in Figure 5, in the three-point bending test on the new roller 5, the roller 5 withstood a relatively large test force until the test force F A caused it to break. The displacement (mm) of the roller 5 at that time was D A at that time.

[0026] After the roller hearth furnace 1 with the new roller 5 installed was operated for 9 months, a three-point bending test was conducted on the roller 5. As shown in Figure 5, the roller 5 broke under a relatively small test force, that is, the test force F B at that time. The displacement (mm) of the roller 5 at that time was D B at that time.

[0027] That is, when the amplitude of the output signal of the AE sensor 101 is small as shown in Figure 4(A), the roller 5 withstood a relatively large test force F A until the amplitude of the output signal of the AE sensor 101 is large as shown in Figure 4(B), and it broke under a relatively small test force F B at that time.

[0028] From the output signal of the AE sensor 101 in Figure 4 and the results of the three-point bending test shown in Figure 5, it was found that when the roller 5 is new, that is, when it is not deteriorated, the amplitude of the output signal of the AE sensor 101 is small and it can withstand a large test force. In the case of the roller 5 after the roller hearth furnace 1 has been operated for 9 months, that is, when it is expected that deterioration has progressed, the amplitude of the output signal of the AE sensor 101 is large and it breaks when a small test force is applied.

[0029] Regarding the four rollers A, B, C, and D, measurements were made on the relationship between the roller strength and the amplitude of the output signal of the AE sensor 101, and the results were as shown in Table 1. The amplitude of the output signal of the AE sensor 101 was measured respectively, and the roller strength was measured by a three-point bending test. Table 1 JPEG2025091230000002.jpg4083

[0030] Figure 6 shows these measurement results with the vertical axis representing the roller strength (N) and the horizontal axis representing the amplitude (V). As shown in Table 1 and Figure 6, when the amplitude of the output signal of the AE sensor 101 is small, such as 0.58 (V) or 0.69 (V), the roller strength is large, such as 10738 (N) or 11539 (N), and when the amplitude of the output signal of the AE sensor 101 is large, such as 1.97 (V), the roller strength is small, such as 2011 (N) or 4318 (N). Thus, there is a correlation between the strength of roller 5 and the amplitude of the output signal of the AE sensor 101.

[0031] In a conveying roller device such as the roller hearth kiln 1, in the case of conveying in a corrosive atmosphere with respect to the roller material, for example, when lithium vapor that corrodes the ceramic roller is generated during the process of firing a fired product containing a lithium compound, the wall thickness of the ceramic roller gradually becomes thinner due to corrosion. As the strength of the roller decreases, the roller 5 tends to deflect under the pressure from the conveyed object, for example, the sagger containing the fired product.

[0032] As the roller 5 deteriorates due to the operation of the roller hearth kiln 1 and its wall thickness becomes thinner, it is considered that minute cracks occur inside the roller, and the amplitude of the output signal of the AE sensor 101 increases. From such a relationship, it is possible to know to what extent the roller strength has decreased from the amplitude of the output signal of the AE sensor 101.

[0033] In FIG. 3, the analysis unit 106 determines the degree of deterioration of the roller 5 based on the relationship between the amplitude of the output signal of the AE sensor 101 measured by the amplitude measurement unit 105 and the amplitude shown in FIG. 5 and the test force at the time of fracture, and the relationship between the amplitude shown in FIG. 6 and the strength of the roller 5. The determination unit 107 predicts the replacement timing of the roller 5 based on the analysis result of the degree of deterioration of the roller 5 by the analysis unit 106. In this way, when the amplitude of the output signal of the AE sensor 101 reaches a predetermined value, the roller 5 is replaced. This replacement timing can be alerted by being displayed on the display of the control device of the roller hearth furnace 1 and also by sound.

[0034] Although a large number of rollers 5 are installed in the roller hearth furnace 1, in this embodiment, it is not possible to identify the roller that has deteriorated to the extent that it should be replaced. Since ceramic rollers with excellent wear resistance are used in the roller hearth furnace 1, it is assumed that the main cause of deterioration of the roller 5 is due to corrosive gas, and a plurality of rollers installed in the high-temperature zones among the plurality of zones are sequentially replaced. In this way, during the operation of the roller hearth furnace 1, that is, without stopping the operation, the deteriorated roller can be replaced.

[0035] In the embodiment shown in FIG. 3, an example in which the amplitude measurement unit, the analysis unit, and the determination unit are configured by hardware has been described, but a series of processes can be executed by a computer as software shown in the flowchart of FIG. 7.

[0036] As shown in FIG. 7, the signal detected by the AE sensor 101 in FIG. 3 is amplified by the preamplifier 102 and input to an arithmetic circuit (not shown) (S102). A signal that is considered to be caused by deterioration such as minute cracks occurring in the roller 5 is extracted (S103). The signal caused by this deterioration is amplified (S104). The amplitude of this signal is determined, and the degree of progress of the deterioration is determined from this amplitude (S105). The replacement timing of the roller 5 is predicted from the degree of progress of this deterioration (S106).

[0037] According to the embodiment described above, it is possible to detect the deterioration of the conveying rollers during the operation of a conveying roller device including a plurality of conveying rollers. As a result, it becomes possible to replace the deteriorated rollers and continue the operation without stopping the operation of the conveying roller device.

Explanation of Signs

[0038] 1 Roller hearth kiln 2 Heating furnace 3 Side wall 31 Upper side wall 32 Roller part side wall 4 Pedestal 5 Roller 51 Roller support part 6 Sagger 7 Arrow 101 Acoustic emission (AE) sensor 102 Preamplifier 103 Filter 104 Main amplifier 105 Amplitude measurement part 106 Analysis part 107 Judgment part

Claims

1. An apparatus for detecting deterioration of a conveying roller, comprising: an acoustic sensor for detecting an elastic wave generated by the conveying roller; an amplitude measuring unit for measuring an amplitude of a detection signal from the acoustic sensor; and an analysis unit for determining a degree of deterioration of the conveying roller from the amplitude.

2. The apparatus for detecting deterioration of a conveying roller according to claim 1, further comprising a determination unit for predicting a replacement timing of the conveying roller based on an analysis result of the analysis unit.

3. The apparatus for detecting deterioration of a conveying roller according to claim 1, wherein a plurality of the conveying rollers are provided and the conveying roller can be replaced from outside the apparatus without stopping its operation, and a degree of deterioration of the conveying roller is determined.

4. A method for detecting deterioration of a conveying roller, comprising: detecting an elastic wave generated by the conveying roller by an acoustic sensor; determining an amplitude of a detection signal from the acoustic sensor and determining a degree of deterioration of the conveying roller from the amplitude.

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