Method for measuring fine bubble concentration, and apparatus for measuring fine bubble concentration

Abstract

This invention provides a method for easily measuring the number concentration of fine bubbles in an oil-water mixture. [Solution] The fine bubble concentration measurement method comprises a liquid preparation step (#10), a viscosity measurement step (#20), and a concentration determination step (#30). The liquid preparation step (#10) prepares an oil-water mixture containing fine bubbles to be measured. The viscosity measurement step (#20) measures the viscosity of the oil-water mixture. The concentration determination step (#30) determines the number concentration of fine bubbles in the oil-water mixture based on the viscosity.

Description

[Technical Field]

[0001] The present disclosure relates to a fine bubble concentration measurement method and a fine bubble concentration measurement apparatus. More specifically, the present disclosure relates to a fine bubble concentration measurement method and a fine bubble concentration measurement apparatus for measuring the number concentration of fine bubbles in an oil-water mixture containing fine bubbles. [Background Art]

[0002] Oil-water mixtures containing fine bubbles are used in various fields. For example, in the field of processing such as removal processing or cold plastic working, a processing fluid (coolant) is indispensable. As this processing fluid, an oil-water mixture containing fine bubbles may be used.

[0003] A technique using a processing fluid containing fine bubbles is described, for example, in Japanese Patent Laid-Open No. 2007-331088 (Patent Document 1). Patent Document 1 describes that by including microbubbles in the processing fluid during removal processing, processing accuracy and processing speed can be improved, and tool wear can be reduced. As described above, in processing, a processing fluid containing fine bubbles is useful in terms of extending tool life and improving processing efficiency. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Laid-Open No. 2007-331088 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] In machining processes using an oil-water mixture containing fine bubbles as a processing fluid, it is necessary to control the number concentration of fine bubbles in the oil-water mixture (processing fluid) in order for the processing fluid to perform well. While it is possible to directly measure the number concentration of fine bubbles in an oil-water mixture using specialized precision measuring instruments, introducing such instruments into a machining environment is not practical. Therefore, it is desirable to be able to easily measure the number concentration of fine bubbles in an oil-water mixture without using precision measuring instruments.

[0006] The purpose of this disclosure is to provide a fine bubble concentration measurement method and a fine bubble concentration measurement device that can easily measure the number concentration of fine bubbles in an oil-water mixture. [Means for solving the problem]

[0007] The fine bubble concentration measurement method according to this disclosure comprises a liquid preparation step, a viscosity measurement step, and a concentration determination step. The liquid preparation step involves preparing an oil-water mixture containing fine bubbles to be measured. The viscosity measurement step involves measuring the viscosity of the oil-water mixture. The concentration determination step involves determining the number concentration of fine bubbles in the oil-water mixture based on the viscosity.

[0008] The fine bubble concentration measuring device according to this disclosure is a measuring device for measuring the number concentration of fine bubbles in an oil-water mixture. The measuring device comprises a viscometer and a calculation device. The viscometer measures the viscosity of the oil-water mixture. The calculation device calculates the number concentration of fine bubbles in the oil-water mixture to be measured based on the viscosity. [Effects of the Invention]

[0009] According to this disclosure, the number concentration of fine bubbles in an oil-water mixture can be easily measured. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing an example of a processing apparatus. [Figure 2]Figure 2 is a flowchart showing the fine bubble concentration measurement method of the first embodiment. [Figure 3] Figure 3 is a schematic diagram showing a part of the fine bubble concentration measuring device that can be used in the fine bubble concentration measuring method of the first embodiment. [Figure 4] Figure 4 is a schematic diagram showing an example of the correlation between viscosity and the number concentration of fine bubbles (FB concentration). [Figure 5] Figure 5 is a flowchart showing the fine bubble concentration measurement method of the second embodiment. [Figure 6] Figure 6 is a schematic diagram showing a fine bubble concentration measuring device that can be used in the fine bubble concentration measuring method of the fourth embodiment. [Modes for carrying out the invention]

[0011] To achieve the above objective, the inventors diligently studied a method for easily measuring the number concentration of fine bubbles in an oil-water mixture, rather than directly measuring it using special precision measuring instruments. In this specification, the number concentration of fine bubbles in an oil-water mixture may be referred to as "FB concentration." In this specification, a fine bubble means a microbubble with an average diameter of less than 100.00 μm, as defined in JIS B 8741-1:2019. Microbubbles mean microbubbles with an average diameter of 1.00 μm or more and less than 100.00 μm, and ultrafine bubbles mean microbubbles with an average diameter of 0.01 μm or more and less than 1.00 μm. The average diameter of a fine bubble means the median diameter D50.

[0012] As a result of their investigation, the inventors have found the following: When an oil-water mixture contains fine bubbles, its viscosity changes significantly depending on the FB concentration. On the other hand, even if oil alone without water contains fine bubbles, its viscosity hardly changes. Similarly, even if water alone without oil contains fine bubbles, its viscosity hardly changes. In the case of an oil-water mixture, the state of the interface between water and oil changes depending on the FB concentration, and it is thought that this change in the interface state causes a change in viscosity.

[0013] The viscosity of an oil-water mixture shows a positive correlation with the fine bubble (FB) concentration. Specifically, viscosity increases as the FB concentration increases. Conversely, viscosity decreases as the FB concentration decreases. When the FB concentration is zero, meaning the oil-water mixture contains no fine bubbles, the viscosity is lowest.

[0014] Therefore, it can be said that the FB concentration can be determined by measuring viscosity. Thus, viscosity can serve as an indicator for managing FB concentration. Measuring viscosity is simpler than directly measuring FB concentration using specialized precision measuring instruments.

[0015] The fine bubble concentration measurement method and fine bubble concentration measurement apparatus according to the embodiments of this disclosure were completed based on the above findings.

[0016] The fine bubble concentration measurement method according to this embodiment comprises a liquid preparation step, a viscosity measurement step, and a concentration determination step. The liquid preparation step involves preparing an oil-water mixture containing fine bubbles to be measured. The viscosity measurement step involves measuring the viscosity of the oil-water mixture. The concentration determination step involves determining the number concentration of fine bubbles in the oil-water mixture based on the viscosity (first configuration).

[0017] In the first configuration of the measurement method, the viscosity of the oil-water mixture to be measured is measured in the viscosity measurement step. As described above, viscosity shows a positive correlation with the number concentration of fine bubbles (FB concentration) in the oil-water mixture. Therefore, in the concentration determination step, the FB concentration in the oil-water mixture to be measured can be determined based on the viscosity measured in the viscosity measurement step. Furthermore, viscosity measurement does not require the use of special precision measuring instruments. Thus, the FB concentration can be easily measured according to the measurement method of the first configuration.

[0018] In the fine bubble concentration measurement method described above, in a typical example, the oil-water mixture contains 1.0% by mass or more of water and 1.0% by mass or more of oil (second configuration). That is, the oil-water mixture is neither a simple oil containing no water nor a simple water containing no oil.

[0019] In the fine bubble concentration measurement method described above, preferably, the viscosity of the oil-water mixture is 30 mPa·s or less at a liquid temperature of 25°C (third configuration). That is, the viscosity of the oil-water mixture is relatively low, and the oil-water mixture tends to flow easily.

[0020] In the fine bubble concentration measurement method described above, preferably, in the viscosity measurement step, a tuning-fork vibration viscometer is used as the viscometer to measure the viscosity of the oil-water mixture (fourth configuration). In this case, it becomes possible to accurately measure the viscosity of the oil-water mixture containing fine bubbles.

[0021] The fine bubble concentration measurement method described above preferably further comprises a reference data setting step. In the reference data setting step, a viscosity measurement step is performed in advance on a reference oil-water mixture with a known number concentration of fine bubbles, and the viscosity corresponding to the reference oil-water mixture is obtained as reference data. In this case, in the concentration determination step, the viscosity corresponding to the target oil-water mixture to be measured obtained in the viscosity measurement step may be collated with the reference data corresponding to the reference oil-water mixture obtained in the reference data setting step, to obtain the number concentration of fine bubbles in the target oil-water mixture to be measured (fifth configuration).

[0022] In the case of the measurement method according to the fifth configuration, in the concentration determination step, the FB concentration in the target oil-water mixture to be measured is obtained by collating the viscosity corresponding to the target oil-water mixture to be measured with the reference data. Here, as the reference data, for example, viscosities respectively corresponding to two or more reference oil-water mixtures with known FB concentrations and different from each other can be used. In this case, in the reference data, an FB concentration (known) is assigned to the viscosity of each reference oil-water mixture. Hereinafter, this reference data is also referred to as individual reference data.

[0023] Furthermore, similar to individual reference data, when using the viscosity of two or more reference oil-water mixtures with known and different FB concentrations, a calibration curve showing the correlation between viscosity and FB concentration may be established as reference data from the viscosity of each reference oil-water mixture and its FB concentration. Hereinafter, this reference data will also be referred to as calibration curve data. In the calibration curve data, the FB concentration is expressed as a positive function of viscosity. The number of reference oil-water mixtures that form the basis of the calibration curve data may be two or more, but preferably five or more.

[0024] In the fifth configuration of the measurement method, when individual reference data is adopted in the concentration determination step, the viscosity corresponding to the oil-water mixture to be measured is compared with the reference data. If a matching reference data is found as a result of the comparison, the FB concentration (known) assigned to that reference data can be determined as the FB concentration in the oil-water mixture to be measured. If no matching reference data is found as a result of the comparison in the concentration determination step, two reference data and their assigned FB concentrations (known) can be selected, and the FB concentration in the oil-water mixture to be measured can be determined by interpolation or extrapolation.

[0025] Furthermore, when calibration curve data is used in the concentration determination process, the viscosity corresponding to the oil-water mixture being measured is compared with the calibration curve data. Through this comparison, the corresponding FB concentration in the calibration curve data can be determined as the FB concentration in the oil-water mixture being measured.

[0026] In the fine bubble concentration measurement method according to the fifth configuration, preferably, the reference oil-water mixture includes a lower limit reference oil-water mixture having a lower limit number concentration where the number concentration of fine bubbles is at the lower limit of control, and an upper limit reference oil-water mixture having an upper limit number concentration where the number concentration of fine bubbles is at the upper limit of control. The reference data includes lower limit reference data corresponding to the lower limit reference oil-water mixture and upper limit reference data corresponding to the upper limit reference oil-water mixture. In this case, in the concentration determination step, the viscosity corresponding to the oil-water mixture to be measured, obtained in the viscosity measurement step, may be compared with the lower limit reference data and the upper limit reference data to determine the number concentration of fine bubbles in the oil-water mixture to be measured (sixth configuration).

[0027] In the sixth configuration of the measurement method, in the concentration determination step, the FB concentration in the oil-water mixture to be measured is determined by comparing the viscosity corresponding to the oil-water mixture to be measured with lower limit reference data and upper limit reference data. Here, the lower limit reference data is based on the viscosity corresponding to the lower limit reference oil-water mixture, and in the lower limit reference data, the lower limit number concentration of fine bubbles (known) is assigned to the lower limit reference oil-water mixture. On the other hand, the upper limit reference data is based on the viscosity corresponding to the upper limit reference oil-water mixture, and in the upper limit reference data, the upper limit number concentration of fine bubbles (known) is assigned to the upper limit reference oil-water mixture. For example, if the oil-water mixture to be measured is a processing fluid, the FB concentration of the lower limit reference oil-water mixture and the FB concentration of the upper limit reference oil-water mixture correspond to the lower limit and upper limit of the FB concentration range that can be suitably used as a processing fluid, respectively.

[0028] In the sixth configuration of the measurement method, in the concentration determination step, the viscosity corresponding to the oil-water mixture to be measured is compared with the lower limit reference data and the upper limit reference data. If a matching reference data (lower limit reference data or upper limit reference data) is found as a result of the comparison, the FB concentration (lower limit number concentration or upper limit number concentration) assigned to that reference data can be determined as the FB concentration in the oil-water mixture to be measured. In the concentration determination step, if no matching reference data (lower limit reference data or upper limit reference data) is found as a result of the comparison, the FB concentration in the oil-water mixture to be measured can be determined by interpolation or extrapolation calculation by referring to the lower limit reference data, the upper limit reference data, and the FB concentration (lower limit number concentration or upper limit number concentration) assigned to them. In this case, the lower limit reference data and the upper limit reference data are the individual reference data described above.

[0029] In the fine bubble concentration measurement method described above, the average diameter of the fine bubbles may be 0.05 μm or more and 50.00 μm or less (composition 7). That is, the fine bubbles may include ultrafine bubbles with an average particle size of 0.05 μm or more and less than 1.00 μm, or microbubbles with an average diameter of 1.00 μm or more and 50.00 μm or less.

[0030] In the fine bubble concentration measurement method described above, a typical example is that the oil-water mixture is the processing fluid used in machining (composition 8). In this case, the FB concentration in the processing fluid can be controlled to an appropriate state. Therefore, the processing fluid can perform well during machining, which in turn extends tool life and improves machining efficiency.

[0031] The fine bubble concentration measuring device according to this embodiment is a measuring device for measuring the number concentration of fine bubbles in an oil-water mixture. The measuring device comprises a viscometer and a calculation device. The viscometer measures the viscosity of the oil-water mixture. The calculation device calculates the number concentration of fine bubbles in the oil-water mixture to be measured based on the viscosity (9th configuration).

[0032] According to the measuring device of the ninth configuration, it is possible to measure the viscosity of the oil-water mixture to be measured using a viscometer. As described above, viscosity shows a positive correlation with the number concentration of fine bubbles (FB concentration) in the oil-water mixture, so the FB concentration in the oil-water mixture to be measured can be determined based on the viscosity. Furthermore, viscosity measurement does not require the use of special precision measuring instruments. Therefore, the FB concentration can be measured easily.

[0033] The fine bubble concentration measuring device according to the ninth configuration may further include a memory device. The memory device stores data showing the correlation between viscosity and the number concentration of fine bubbles. The calculation device determines the number concentration of fine bubbles in the oil-water mixture to be measured based on the viscosity measured by the viscometer and the data stored in the memory device (tenth configuration).

[0034] In the tenth configuration of the measuring device, the FB concentration in the oil-water mixture to be measured can be determined by a calculation unit based on the viscosity measured by a viscometer for the oil-water mixture to be measured, and data showing the correlation between viscosity and FB concentration stored in a memory device.

[0035] In the fine bubble concentration measuring device according to the ninth or tenth configuration, the viscometer is preferably a tuning fork vibrating viscometer (eleventh configuration). In this case, it is possible to accurately measure the viscosity of an oil-water mixture containing fine bubbles.

[0036] The fine bubble concentration measurement method and fine bubble concentration measurement apparatus according to this embodiment will be described below with reference to the drawings. In each figure, the same or equivalent components are denoted by the same reference numerals, and redundant explanations will not be repeated.

[0037] [First Embodiment] The fine bubble concentration measurement method and fine bubble concentration measurement apparatus according to this embodiment are used to measure the number concentration of fine bubbles in an oil-water mixture containing fine bubbles. The following explanation will use the case where the oil-water mixture to be measured is a processing fluid (coolant) as an example. First, processing using a processing fluid will be described.

[0038] [Regarding processing using an oil-water mixture containing fine bubbles as a processing fluid] The processing includes material removal and cold plastic deformation. Material removal processes can be broadly classified into cutting, grinding, and polishing. Cold plastic deformation processes can be broadly classified into wire drawing, cold drawing, cold extrusion, and cold rolling. In these processes, the tool is brought into contact with the workpiece to perform the processing. The processing yields parts such as intermediate or final parts. The material of the workpiece is not particularly limited. For example, if the processing is material removal or cold plastic deformation, the material of the workpiece is metal. In this case, the workpiece is a metallic material, and the part manufactured by the processing is a metallic material. If the processing is material removal, the material of the workpiece may be ceramics, glass, or CFRP (carbon fiber reinforced plastic), etc. The processing is carried out by processing equipment.

[0039] Figure 1 is a schematic diagram showing an example of a processing apparatus. In the example shown in Figure 1, the processing apparatus 1000 is used for material removal. The processing apparatus 1000 comprises a tool 1001, a jig 1002, and a fine bubble generator 1003. Processing with the processing apparatus 1000 uses a processing fluid PF. This processing fluid PF is an oil-water mixture containing fine bubbles. The processing apparatus 1000 may also be used for cold plastic deformation.

[0040] Tool 1001 performs machining on the workpiece W. Jig 1002 fixes the workpiece W in place.

[0041] The fine bubble generator 1003 generates fine bubbles in the processing liquid PF. The fine bubble generator 1003 comprises, for example, a processing liquid storage container 1031, a fine bubble generator 1032, a supply pipe 1033, a discharge pipe 1034, and a processing liquid discharge mechanism 1035.

[0042] The processing fluid storage container 1031 is a container capable of storing the processing fluid PF. The processing fluid storage container 1031 is, for example, a tank or a bathtub. The fine bubble generator 1032 generates fine bubbles in the processing fluid PF.

[0043] The supply pipe 1033 is located between the processing fluid storage container 1031 and the fine bubble generator 1032, connecting the processing fluid storage container 1031 and the fine bubble generator 1032. The supply pipe 1033 supplies the processing fluid PF stored in the processing fluid storage container 1031 to the fine bubble generator 1032.

[0044] The discharge pipe 1034 is positioned between the processing fluid storage container 1031 and the fine bubble generator 1032, connecting the processing fluid storage container 1031 and the fine bubble generator 1032. The discharge pipe 1034 discharges the processing fluid PF, which has had fine bubbles generated by the fine bubble generator 1032, from the fine bubble generator 1032 to the processing fluid storage container 1031. As a result, the processing fluid PF containing fine bubbles is stored in the processing fluid storage container 1031.

[0045] The processing fluid PF is a water-soluble processing fluid (coolant) and is an oil-water mixture. The oil-water mixture contains 1.0% or more water and 1.0% or more oil by mass. That is, the oil-water mixture is neither pure oil without water (i.e., a liquid containing 100% oil) nor pure water without oil (i.e., a liquid containing 100% water). The viscosity of the oil-water mixture is 30 mPa·s or less at a liquid temperature of 25°C. That is, the viscosity of the oil-water mixture is relatively low, and the oil-water mixture flows easily. The water-soluble processing fluid (oil-water mixture) is, for example, one selected from the group consisting of emulsion type, soluble type, and solution type.

[0046] Preferably, the processing fluid PF is an emulsion-type water-soluble processing fluid. The emulsion-type water-soluble processing fluid contains, for example, water and a surfactant as an oil. The surfactant can be any well-known type. The surfactant is, for example, one or more selected from the group consisting of nonionic surfactants, anionic surfactants, amphoteric surfactants, and cationic surfactants.

[0047] If the processing fluid PF is an emulsion-type water-soluble processing fluid, it may contain other components besides water and surfactants. These other components may include, for example, extreme pressure additives, rust inhibitors, preservatives, friction reducers, etc.

[0048] In the processing fluid PF, i.e., an oil-water mixture, the average diameter of the fine bubbles is, for example, between 0.05 μm and 50.00 μm.

[0049] The processing fluid discharge mechanism 1035 comprises a drive source 1351, piping 1352, and a nozzle 1353. One end of piping 1352 is immersed in the processing fluid PF stored in the processing fluid storage container 1031. The other end of piping 1352 is connected to the nozzle 1353. The drive source 1351 supplies the processing fluid PF from the processing fluid storage container 1031 to the nozzle 1353 via piping 1352. The drive source 1351 is, for example, a pump.

[0050] During machining, the nozzle 1353 sprays a machining fluid PF containing fine bubbles and supplies the sprayed machining fluid PF to the workpiece W and the tool 1001. Specifically, the nozzle 1353 flows the machining fluid PF over the part of the tool 1001 that is in contact with the workpiece W, and / or over the part of the workpiece W that is in contact with the tool 1001. In other words, when machining is being performed, the nozzle 1353 flows and supplies the machining fluid PF to the machining point P0.

[0051] The processing apparatus 1000 may further include a processing fluid recovery device 1004. The processing fluid recovery device 1004 includes a recovery pan 1041 and a recovery pipe 1042. The recovery pan 1041 functions as a receptacle for recovering the processing fluid PF discharged from the nozzle 1353 and flowing down to the processing point P0. The recovery pipe 1042 is positioned between the recovery pan 1041 and the processing fluid storage container 1031, connecting the recovery pan 1041 and the processing fluid storage container 1031. The recovery pipe 1042 discharges the processing fluid PF stored in the recovery pan 1041 to the processing fluid storage container 1031. The processing fluid recovery device 1004 allows the processing fluid PF to be circulated and utilized. However, the processing apparatus 1000 does not necessarily have to include the processing fluid recovery device 1004.

[0052] In machining using such a machining apparatus 1000, the tool 1001 is brought into contact with the workpiece W to perform machining and manufacture parts. The parts manufactured are intermediate or final parts. While machining is being performed, a machining fluid PF containing fine bubbles is sprayed from the nozzle 1353 and supplied to the machining point P0. This improves the life of the tool 1001 and improves machining efficiency.

[0053] In processing using a processing fluid PF containing fine bubbles, the number concentration of fine bubbles (FB concentration) in the processing fluid PF is controlled so that the processing fluid PF exhibits good performance. For example, a lower limit number concentration and an upper limit number concentration are set as control standards for the FB concentration of the processing fluid PF. The lower limit number concentration is, for example, 5,000 bubbles / mL, preferably 10,000 bubbles / mL. The upper limit number concentration is, for example, 5,000,000,000 bubbles / mL, preferably 1,000,000,000 bubbles / mL.

[0054] If the FB concentration in the processing fluid PF falls below the lower limit number concentration, for example, the processing speed is reduced and processing continues. In some cases, processing is stopped and the fine bubble generator 1032 is cleaned. On the other hand, if the PB concentration in the processing fluid PF exceeds the upper limit number concentration, new processing fluid PF is added to the processing fluid storage container 1031.

[0055] The following describes a method and apparatus for measuring the fine bubble concentration for controlling the FB concentration in the processing fluid PF.

[0056] [Regarding methods and devices for measuring fine bubble concentration] Referring to Figures 2 and 3, the fine bubble concentration measurement method and fine bubble concentration measurement apparatus of this embodiment will be described. Figure 2 is a flow chart showing the fine bubble concentration measurement method of this embodiment. As shown in Figure 2, the fine bubble concentration measurement method of this embodiment comprises a liquid preparation step (#10), a viscosity measurement step (#20), and a concentration determination step (#30).

[0057] The liquid preparation step (#10) involves preparing the oil-water mixture ML (Figure 3) to be measured, which contains fine bubbles. In this embodiment, the oil-water mixture ML to be measured is the processing fluid PF used in processing by the processing apparatus 1000. The processing fluid PF stored in the processing fluid storage container 1031 is taken as the oil-water mixture ML to be measured.

[0058] Figure 3 is a schematic diagram showing a part of the fine bubble concentration measuring device 100 that can be used in the fine bubble concentration measuring method of this embodiment. Referring to Figure 3, the fine bubble concentration measuring device 100 comprises a viscometer 1 and a measuring cell 2. Although Figure 3 shows the viscometer 1 and the measuring cell 2 in a relatively close position, the viscometer 1 and the measuring cell 2 can be separated.

[0059] In this embodiment, the viscometer 1 is a tuning fork vibration type viscometer. As the tuning fork vibration type viscometer, for example, model SV-10 manufactured by A&D Co., Ltd. can be used. Specifically, the viscometer 1 includes a U-shaped tuning fork section 11, an electromagnetic drive section 12, a displacement sensor 13, and a control section 14. The tuning fork section 11 has a pair of vibrators 111. The electromagnetic drive section 12 applies vibration to the vibrators 111, causing the vibrators 111 to resonate at a constant amplitude. The displacement sensor 13 detects the amplitude of the vibrators 111. The control section 14 is connected to the electromagnetic drive section 12 and the displacement sensor 13 and controls the operation of the electromagnetic drive section 12. With a viscometer 1 configured in this way, the electromagnetic drive section 12 causes the vibrators 111 to resonate when they are immersed in a liquid (oil-water mixture). The control unit 14 detects the excitation force required to move the vibrator 111 with a constant amplitude, that is, the drive current of the electromagnetic drive unit 12. The control unit 14 further compares the detected drive current with a calibration curve that shows the correlation between drive current and viscosity, which is stored in advance, and thereby calculates the viscosity of the liquid (oil-water mixture).

[0060] The measuring cell 2 has, for example, a rectangular tube shape with an open top. The measuring cell 2 only needs to have an open top; its shape is not particularly limited. The oil-water mixture ML to be measured, i.e., the collected processing fluid PF, is contained within the measuring cell 2.

[0061] Returning to Figure 2, the viscosity measurement step (#20) involves using the viscometer 1 to measure the viscosity ve of the oil-water mixture ML to be measured. Specifically, the measuring cell 2 is placed below the viscometer 1, and the transducer 111 of the viscometer 1 is immersed in the oil-water mixture ML in the measuring cell 2. Then, as described above, the viscometer 1 is used to resonate the transducer 111 in the oil-water mixture ML, and the viscosity ve corresponding to the oil-water mixture ML to be measured is determined.

[0062] The concentration determination step (#30) determines the number concentration of fine bubbles in the oil-water mixture ML to be measured, based on the viscosity ve obtained in the viscosity measurement step (#20). Here, viscosity shows a positive correlation with the number concentration of fine bubbles (FB concentration) in the oil-water mixture ML. That is, the FB concentration can be expressed as a positive function of viscosity.

[0063] Figure 4 is a schematic diagram showing an example of the correlation between viscosity and the number concentration of fine bubbles (FB concentration). In the example shown in Figure 4, the FB concentration is expressed as a quadratic function of viscosity (convex downwards). This function can be used as a calibration curve. This calibration curve corresponds to the calibration curve data described above. Therefore, in the concentration determination step (#30), the FB concentration in the oil-water mixture ML to be measured can be determined based on this calibration curve and the viscosity ve obtained in the viscosity measurement step (#20). Furthermore, viscosity measurement does not require the use of special precision measuring instruments. Therefore, according to this embodiment, the FB concentration can be measured easily.

[0064] However, as is common technical knowledge, the viscosity of a liquid changes with temperature. Therefore, when performing the viscosity measurement process (#20) and creating calibration curve data, it is necessary to measure the viscosity under conditions where the temperature of the oil-water mixture (liquid temperature) is kept constant. For example, the liquid temperature during viscosity measurement is 25°C.

[0065] In this embodiment, the oil-water mixture ML is the machining fluid PF used for processing. In this case, the FB concentration in the machining fluid PF can be controlled to an appropriate state. Therefore, the machining fluid PF can perform well during processing, which in turn extends the life of the tool 1001 and improves processing efficiency.

[0066] In this embodiment, the viscometer 1 is a tuning fork vibrating viscometer. In this case, compared to a rotational viscometer, such as a type B viscometer, it is possible to accurately measure the viscosity of an oil-water mixture ML containing fine bubbles. However, instead of the tuning fork vibrating viscometer, another type of viscometer, such as a rotational viscometer, may be used as the viscometer 1.

[0067] [Second Embodiment] Figure 5 is a flowchart showing the fine bubble concentration measurement method of the second embodiment. Referring to Figure 5, the fine bubble concentration measurement method of this embodiment differs from the fine bubble concentration measurement method of the first embodiment mainly in that it includes a reference data setting step (#5).

[0068] As shown in Figure 5, the fine bubble concentration measurement method of this embodiment includes a liquid preparation step (#10), a viscosity measurement step (#20), and a concentration determination step (#30), and further includes a reference data setting step (#5) before each of these steps (#10 to #30). In the reference data setting step (#5), the viscosity measurement step (#20) is performed on two or more reference oil-water mixtures L1, L2, ... whose number concentrations of fine bubbles are known and different from each other, and the viscosities v1, v2, ... corresponding to each of the reference oil-water mixtures L1, L2, ... are determined as reference data.

[0069] For example, the reference data is the individual reference data described above. Specifically, the reference data uses the viscosities v1, v2, ... corresponding to two or more reference oil-water mixtures L1, L2, ... whose FB concentrations are known. In this case, the FB concentrations of the reference oil-water mixtures L1, L2, ... are known, and in the reference data, the FB concentration (known) is assigned to the viscosities v1, v2, ... of each reference oil-water mixture L1, L2, ....

[0070] The known FB concentrations of the reference oil-water mixtures L1, L2, ... can be obtained using a special precision measuring instrument. This precision measuring instrument is, for example, a laser diffraction particle size distribution analyzer (product name: SALD-7500nano, manufactured by Shimadzu Corporation). In this embodiment, the FB concentrations of the reference oil-water mixtures L1, L2, ... are not particularly limited and can be arbitrarily selected. One of the reference oil-water mixtures L1, L2, ... may be an oil-water mixture with an FB concentration of zero, that is, an oil-water mixture that does not contain fine bubbles.

[0071] In the measurement method of this embodiment, the viscosity ve of the oil-water mixture ML to be measured is determined through the liquid preparation step (#10) and the viscosity measurement step (#20) as described above. Then, in the concentration determination step (#30), the viscosity ve is compared with the reference data (viscosity v1, v2, ...) corresponding to each of the reference oil-water mixtures L1, L2, ... obtained in the reference data setting step (#5), and the number concentration of fine bubbles in the oil-water mixture ML to be measured is determined.

[0072] Specifically, the viscosity ve corresponding to the oil-water mixture ML to be measured is compared with reference data (viscosity v1, v2, ...). If a matching reference data is found, the FB concentration (known) assigned to that reference data can be determined as the FB concentration in the oil-water mixture ML to be measured. On the other hand, if no matching reference data is found, two reference data points (viscosity v1, v2, ...) are selected, along with the FB concentrations (known) assigned to them. By referring to these selected values, the FB concentration in the oil-water mixture ML to be measured can be determined by interpolation or extrapolation.

[0073] The reference data may be the calibration curve data described above. Specifically, similar to the individual reference data, the viscosities v1, v2, ... corresponding to two or more reference oil-water mixtures L1, L2, ... whose FB concentrations are known are used. In this case, calibration curve data showing the correlation between viscosity and FB concentration is determined as reference data from the viscosities v1, v2, ... of each reference oil-water mixture L1, L2, ... and their FB concentrations. In the calibration curve data, the FB concentration is expressed as a positive function of viscosity (Figure 4).

[0074] In this case, the viscosity ve corresponding to the oil-water mixture ML being measured is compared with the calibration curve data. Through this comparison, the corresponding FB concentration in the calibration curve data can be determined as the FB concentration in the oil-water mixture ML being measured.

[0075] In this embodiment, when performing the viscosity measurement step (#20) on the oil-water mixture ML to be measured, and when performing the viscosity measurement step (#20) on the reference oil-water mixtures L1, L2, ... in the reference data setting step (#5), it is necessary to measure the viscosity under conditions where the temperature (liquid temperature) of the oil-water mixture is kept constant. The liquid temperature during viscosity measurement is, for example, 25°C.

[0076] [Third Embodiment] Referring to Figure 5, the fine bubble concentration measurement method of the third embodiment will be described. The fine bubble concentration measurement method of this embodiment differs from the fine bubble concentration measurement method of the second embodiment in that the reference data used in the reference data setting step (#5) is limited.

[0077] In the reference data setting step (#5) of this embodiment, the reference oil-water mixture includes a lower limit reference oil-water mixture LL having a lower limit number concentration where the number concentration of fine bubbles is the lower limit of control, and an upper limit reference oil-water mixture LU having an upper limit number concentration where the number concentration of fine bubbles is the upper limit of control. The reference data includes lower limit reference data corresponding to the lower limit reference oil-water mixture LL and upper limit reference data corresponding to the upper limit reference oil-water mixture LU.

[0078] Specifically, in the reference data setting step (#5), a viscosity measurement step (#20) is performed on the lower limit reference oil-water mixture LL in advance, and the viscosity vl corresponding to the lower limit reference oil-water mixture LL is determined as the lower limit reference data. Similarly, in the reference data setting step (#5), a viscosity measurement step (#20) is performed on the upper limit reference oil-water mixture LU in advance, and the viscosity vu corresponding to the upper limit reference oil-water mixture LU is determined as the upper limit reference data.

[0079] The FB concentration of the lower limit standard oil-water mixture LL is a known lower limit number concentration, and in the lower limit standard data, the lower limit number concentration is assigned to the viscosity vl of the lower limit standard oil-water mixture LL. On the other hand, the FB concentration of the upper limit standard oil-water mixture LU is a known upper limit number concentration, and in the upper limit standard data, the upper limit number concentration is assigned to the viscosity vu of the upper limit standard oil-water mixture LU. The known FB concentrations of the lower limit standard oil-water mixture LL and the upper limit standard oil-water mixture LU can be obtained using special precision measuring instruments. One example of such a precision measuring instrument is a laser diffraction particle size distribution analyzer (product name: SALD-7500nano, manufactured by Shimadzu Corporation).

[0080] In the measurement method of this embodiment, similar to the second embodiment, the viscosity ve of the oil-water mixture ML to be measured is determined through a liquid preparation step (#10) and a viscosity measurement step (#20). Then, in the concentration determination step (#30), the viscosity ve is compared with the lower limit reference data (viscosity vl) corresponding to the lower limit reference oil-water mixture LL, and the upper limit reference data (viscosity vu) of the upper limit reference oil-water mixture LU, which were determined in the reference data setting step (#5), to determine the number concentration of fine bubbles in the oil-water mixture ML to be measured.

[0081] Specifically, the viscosity ve corresponding to the oil-water mixture ML being measured is compared with the lower limit reference data (viscosity vl) and upper limit reference data (viscosity vu). If a matching reference data (lower limit reference data or upper limit reference data) is found as a result of the comparison, the FB concentration (lower limit number concentration or upper limit number concentration) assigned to that reference data can be determined as the FB concentration in the oil-water mixture ML being measured.

[0082] On the other hand, if the comparison does not reveal any matching reference data (lower limit reference data or upper limit reference data), the FB concentration in the oil-water mixture ML being measured can be determined by interpolation or extrapolation calculation by referring to the lower limit reference data (viscosity vl) and upper limit reference data (viscosity vu), as well as the FB concentrations assigned to them (lower limit number concentration, upper limit number concentration).

[0083] Furthermore, if, as a result of the comparison, no matching reference data (lower limit reference data or upper limit reference data) is found, the viscosity ve corresponding to the oil-water mixture ML being measured may be determined to be within the control range if it falls between the lower limit reference data (viscosity vl) and the upper limit reference data (viscosity vu). In other words, if viscosity ve is greater than the lower limit reference data (viscosity vl), the FB concentration of the oil-water mixture ML may be determined to be greater than the lower limit of control (lower limit number concentration). Furthermore, if viscosity ve is less than the upper limit reference data (viscosity vu), the FB concentration of the oil-water mixture ML may be determined to be less than the upper limit of control (upper limit number concentration). In this specification, such determination is included in determining the FB concentration of the oil-water mixture being measured.

[0084] In this embodiment, when performing the viscosity measurement step (#20) on the oil-water mixture ML to be measured, and when performing the viscosity measurement step (#20) on the lower limit reference oil-water mixture LL and the upper limit reference oil-water mixture LU in the reference data setting step (#5), it is necessary to measure the viscosity under conditions where the temperature (liquid temperature) of the oil-water mixture is kept constant. The liquid temperature during viscosity measurement is, for example, 25°C.

[0085] [Fourth Embodiment] Figure 6 is a schematic diagram showing a fine bubble concentration measuring device 100A that can be used in the fine bubble concentration measuring method of the fourth embodiment. The fine bubble concentration measuring device 100A differs from the fine bubble concentration measuring device 100 of the first to third embodiments in that it further includes a storage device 3 and an arithmetic unit 4.

[0086] Specifically, the storage device 3 and the arithmetic unit 4 are components of a computer. The storage device 3 is memory. The arithmetic unit 4 is a CPU on which programs for performing various processes are installed. The arithmetic unit 4 is connected to the storage device 3. The arithmetic unit 4 is connected to the control unit 14 of the viscometer 1. The arithmetic unit 4 may also be connected to a display device 5, such as a display monitor, via an interface.

[0087] The storage device 3 stores data showing the correlation between viscosity and the number concentration of fine bubbles (FB concentration). This data is, for example, individual reference data showing a positive correlation between viscosity and FB concentration, as described above. This individual reference data is, for example, the viscosity v1, v2, ... of each reference oil-water mixture L1, L2, ... and the FB concentration assigned to them, as described above. This individual reference data may also be, for example, the viscosity vl of the lower limit reference oil-water mixture LL and the viscosity vu of the upper limit reference oil-water mixture LU, and the FB concentration (lower limit number concentration, upper limit number concentration) assigned to them, as described above.

[0088] The data stored in the storage device 3 may be the calibration curve data described above.

[0089] In the concentration determination step (#30), the calculation unit 4 acquires the viscosity ve measured by the viscometer 1, and determines the number concentration of fine bubbles in the oil-water mixture ML to be measured based on the acquired viscosity ve and the data stored in the storage device 3. This calculation to determine the FB concentration is performed by a program installed in the calculation unit 4. The determined FB concentration is displayed on the display device 5.

[0090] In the measuring device 100A of this embodiment, the arithmetic unit 4 can determine the FB concentration in the oil-water mixture ML to be measured, based on the viscosity ve measured by the viscometer 1 for the oil-water mixture ML to be measured, and the data showing the correlation between viscosity and FB concentration stored in the storage device 3. [Examples]

[0091] The present disclosure will be further described below with reference to examples. However, the present disclosure is not limited to the following examples.

[0092] A test was conducted to confirm that the viscosity of the oil-water mixture changes depending on the FB concentration.

[0093] In Example 1, a processing solution containing 5% by volume of Sugimura Chemical Industry Co., Ltd.'s processing solution concentrate (product name: Sugicut CE14SZ) was prepared as the oil-water mixture to be measured. This processing solution was placed in the processing solution storage container shown in Figure 1, and fine bubbles were introduced into the processing solution using a fine bubble generator. Then, a processing solution was prepared that had been allowed to stand for 10 minutes after the introduction of fine bubbles. In addition, a processing solution without the introduction of fine bubbles was prepared. Hereinafter, the processing solution containing fine bubbles, as in the former, will be referred to as "FB processing solution," and the processing solution without fine bubbles, as in the latter, will be referred to as "non-FB processing solution."

[0094] For the FB (Fine Bubble) processing solution, two types of FB processing solutions were prepared by changing the introduction time of fine bubbles using a fine bubble generator. The FB concentration of the first FB processing solution was 900,000,000 (bubbles / mL). The FB concentration of the second FB processing solution was 1,800,000,000 (bubbles / mL). The FB concentration of the FB-free processing solution was zero.

[0095] A tuning fork vibrating viscometer (model: SV-10, manufactured by A&D Co., Ltd.) was used as the viscometer. Approximately 10 mL of each processing fluid was taken into a measuring cell, and the viscosity was measured at a liquid temperature of 25°C. Measurements were taken six times at 10-second intervals, and the average value was taken as the viscosity.

[0096] In Example 1, the viscosity of the FB-free processing solution (FB concentration: zero) was 0.94 (mPa·s). The viscosity of the first FB processing solution (FB concentration: 900,000,000 (bubbles / mL)) was 1.01 (mPa·s). The viscosity of the second FB processing solution (FB concentration: 1,800,000,000 (bubbles / mL)) was 1.05 (mPa·s). In the case of such processing solutions, comparing the FB-free processing solution with the second FB processing solution, the viscosity changed by 111.7% due to the inclusion of fine bubbles. Furthermore, these results confirmed that the viscosity of the oil-water mixture changes according to the FB concentration, and that the FB concentration shows a positive correlation with the permeable mass. [Examples]

[0097] Under the same conditions as in Example 1, a test was conducted to confirm that the viscosity of the oil-water mixture changes depending on the FB concentration.

[0098] In Example 2, a processing solution containing 5% by volume of Daido Chemical Co., Ltd.'s processing solution concentrate (product name: Similon SCF500) was prepared as the oil-water mixture to be measured. Other conditions were the same as in Example 1. However, the FB concentration of the first FB processing solution was 1,200,000,000 (particles / mL). The FB concentration of the second FB processing solution was 2,400,000,000 (particles / mL).

[0099] In Example 2, the viscosity of the FB-free processing solution (FB concentration: zero) was 0.89 (mPa·s). The viscosity of the first FB processing solution (FB concentration: 1,200,000,000 (bubbles / mL)) was 0.95 (mPa·s). The viscosity of the second FB processing solution (FB concentration: 2,400,000,000 (bubbles / mL)) was 1.00 (mPa·s). In the case of these processing solutions, comparing the FB-free processing solution with the second FB processing solution, the viscosity changed by 112.4% due to the inclusion of fine bubbles. Furthermore, these results confirmed that the viscosity of the oil-water mixture changes according to the FB concentration, and that the FB concentration shows a positive correlation with the permeable mass. [Examples]

[0100] Under the same conditions as in Example 1, a test was conducted to confirm that the viscosity of the oil-water mixture changes depending on the FB concentration.

[0101] In Example 3, a processing solution containing 5% by volume of Daido Chemical Co., Ltd.'s processing solution concentrate (product name: Similon EX173) was prepared as the oil-water mixture to be measured. Other conditions were the same as in Example 1. However, the FB concentration of the first FB processing solution was 1,100,000,000 (particles / mL). The FB concentration of the second FB processing solution was 2,200,000,000 (particles / mL).

[0102] In Example 3, the viscosity of the FB-free processing solution (FB concentration: zero) was 0.91 (mPa·s). The viscosity of the first FB processing solution (FB concentration: 1,100,000,000 (bubbles / mL)) was 0.96 (mPa·s). The viscosity of the second FB processing solution (FB concentration: 2,200,000,000 (bubbles / mL)) was 1.00 (mPa·s). In the case of these processing solutions, comparing the FB-free processing solution with the second FB processing solution, the viscosity changed by 109.9% due to the inclusion of fine bubbles. Furthermore, these results confirmed that the viscosity of the oil-water mixture changes according to the FB concentration, and that the FB concentration shows a positive correlation with the permeable mass.

[0103] The embodiments of this disclosure have been described above. However, the embodiments described above are merely examples for implementing this disclosure. Therefore, this disclosure is not limited to the embodiments described above, and the embodiments described above can be modified as appropriate without departing from the spirit of the disclosure.

[0104] For example, the oil-water mixture to be measured only needs to contain fine bubbles, and may be an oil-water mixture used in fields other than processing (e.g., milk, lotion). [Explanation of Symbols]

[0105] 100, 100A: Fine bubble concentration measuring device 1: Viscometer 2: Measuring cell 3: Memory device 4: Calculation device

Claims

1. A liquid preparation step to prepare an oil-water mixture containing fine bubbles to be measured, A viscosity measurement step for measuring the viscosity of the oil-water mixture, The system includes a concentration determination step of determining the number concentration of fine bubbles in the oil-water mixture based on the viscosity. Method for measuring fine bubble concentration.

2. A method for measuring the fine bubble concentration according to claim 1, The aforementioned oil-water mixture contains, by mass, 1.0% or more water and 1.0% or more oil. Method for measuring fine bubble concentration.

3. A method for measuring the fine bubble concentration according to claim 1, The viscosity of the oil-water mixture is 30 mPa·s or less at a liquid temperature of 25°C. Method for measuring fine bubble concentration.

4. A method for measuring the fine bubble concentration according to claim 1, In the viscosity measurement step, a tuning fork vibrating viscometer is used as the viscometer to measure the viscosity of the oil-water mixture. Method for measuring fine bubble concentration.

5. A method for measuring the fine bubble concentration according to claim 1, further, The system includes a reference data setting step in which the viscosity measurement step is performed on a reference oil-water mixture in which the number concentration of fine bubbles is known in advance, and the viscosity corresponding to the reference oil-water mixture is determined as reference data. In the concentration determination step, the viscosity corresponding to the oil-water mixture to be measured, obtained in the viscosity measurement step, is compared with the reference data corresponding to the reference oil-water mixture obtained in the reference data setting step, and the number concentration of fine bubbles in the oil-water mixture to be measured is determined. Method for measuring fine bubble concentration.

6. A method for measuring the fine bubble concentration according to claim 5, The standard oil-water mixture includes a lower limit standard oil-water mixture having a lower limit number concentration where the number concentration of the fine bubbles is the lower limit of control, and an upper limit standard oil-water mixture having an upper limit number concentration where the number concentration of the fine bubbles is the upper limit of control. The aforementioned standard data includes lower limit standard data corresponding to the lower limit standard oil-water mixture and upper limit standard data corresponding to the upper limit standard oil-water mixture. In the concentration determination step, the viscosity corresponding to the oil-water mixture to be measured, obtained in the viscosity measurement step, is compared with the lower limit reference data and the upper limit reference data to determine the number concentration of fine bubbles in the oil-water mixture to be measured. Method for measuring fine bubble concentration.

7. A method for measuring the fine bubble concentration according to claim 1, The average diameter of the fine bubbles is between 0.05 μm and 50.00 μm. Method for measuring fine bubble concentration.

8. A method for measuring the concentration of fine bubbles according to any one of claims 1 to 7, The aforementioned oil-water mixture is a processing fluid used in processing. Method for measuring fine bubble concentration.

9. A fine bubble concentration measuring device for measuring the number concentration of fine bubbles in an oil-water mixture, A viscometer for measuring the viscosity of an oil-water mixture, The system includes a calculation device that calculates the number concentration of fine bubbles in the oil-water mixture to be measured based on the viscosity. Fine bubble concentration measuring device.

10. A fine bubble concentration measuring device according to claim 9, further, The device includes a storage device that stores data showing the correlation between viscosity and the number concentration of fine bubbles. The calculation device calculates the number concentration of fine bubbles in the oil-water mixture to be measured based on the viscosity measured by the viscometer and the data stored in the storage device. Fine bubble concentration measuring device.

11. A fine bubble concentration measuring device according to claim 9 or claim 10, The viscometer is a tuning fork vibration type viscometer. Fine bubble concentration measuring device.

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