JP7459712B2 - CLEANING LIQUID REPLACEMENT PREDICTION DEVICE, CLEANING LIQUID REPLACEMENT PREDICTION SYSTEM, CLEANING LIQUID PREDICTION METHOD, AND PROGRAM - Google Patents

Description

The present invention relates to a technology for predicting when to replace a cleaning solution used in cleaning processes such as alkaline immersion degreasing.

Conventionally, in metal processing, etc., a cleaning solution of an alkaline solution to which a surfactant is added as needed is stored in a cleaning tank, and by immersing the workpiece in the cleaning solution stored in the cleaning tank, it is possible to remove the particles that adhere to the surface of the workpiece. Alkaline immersion degreasing treatment is used to remove rust preventive oil, processing oil, etc. Here, the higher the alkalinity of the cleaning liquid, the stronger the cleaning power. However, with long-term use, the alkalinity decreases and the cleaning power deteriorates, making it necessary to replace the cleaning liquid.

Patent Document 1 discloses a technique for measuring the pH value of a cleaning liquid before and after a cleaning operation, and evaluating the cleaning power of the cleaning liquid using the difference between them as an index value. By evaluating the cleaning power of the cleaning liquid using this technique, the user can determine whether or not the cleaning liquid needs to be replaced each time.

Japanese Patent Application Laid-Open No. 10-73583

During operation of the alkaline immersion degreasing equipment, the alkaline cleaning solution stored in the cleaning tank is drawn out from the cleaning tank by a circulation pump, impurities are removed by a filter, and then returned to the cleaning tank. Therefore, the cleaning liquid in the cleaning tank is stirred, and the pH value of the cleaning liquid in the cleaning tank becomes uniform. On the other hand, when the alkali immersion degreasing treatment equipment is not in operation, the circulation pump is stopped, so the cleaning liquid in the cleaning tank is not stirred, and the pH value of the cleaning liquid in the cleaning tank becomes uneven. For this reason, by applying the technology described in Patent Document 1 to alkaline immersion degreasing equipment, the pH value of the cleaning liquid is measured before and after the operation of the cleaning equipment using a sensor installed at a predetermined position in the cleaning tank, and the difference between them is measured. When the cleaning power of the cleaning liquid is evaluated using the index value, depending on the timing, the noise component included in the pH value measured by the sensor becomes large, and there is a possibility that the cleaning power of the cleaning liquid cannot be evaluated correctly.

Further, the technique described in Patent Document 1 does not take any consideration into predicting the future replacement timing. If the future replacement time can be predicted, cleaning fluid can be procured by the predicted replacement time, which has the advantage of reducing cleaning fluid inventory management costs.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a technique that allows highly accurate prediction of when to replace the cleaning liquid used in cleaning processing.

In order to solve the above problems, the present invention provides a method for predicting the time to replace a cleaning solution in cleaning equipment for alkaline immersion degreasing treatment , the cleaning equipment comprising a cleaning tank for storing an alkaline solution cleaning solution to which a surfactant is added as necessary, a filter for removing impurities contained in the cleaning solution, and a circulation pump for circulating the cleaning solution between the cleaning tank and the filter.

In one aspect of the present invention, a sensor installed at a predetermined position in the cleaning tank sequentially measures the pH value of the cleaning liquid in the cleaning tank, and the measured values are arranged in chronological order based on the measurement time to identify a graph showing the change in the pH value of the cleaning liquid in the cleaning tank after the cleaning liquid is added or replaced. Then, a bottom-side change point where the slope of the graph showing the change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive and a top-side change point where the slope changes from positive to negative are extracted, and a filtering process is performed to remove the measured values between the bottom-side change point and the top-side change point, which are arranged in the order of the bottom-side change point and the top-side change point. A regression line is then obtained from the graph after the filtering process, and the regression line is used to calculate the time when the pH value of the cleaning liquid will reach a predetermined threshold value as a pH value that requires replacement of the cleaning liquid, and this time is output as a predicted value for the time to replace the cleaning liquid.

In addition, in the filtering process, the measured values included in the period from the top side change point to the elapse of a predetermined time (pH value stabilization waiting time) are also removed from the graph showing the transition of the pH value of the cleaning liquid in the cleaning tank. You can do it like this.

For example, one aspect of the present invention is
A cleaning solution replacement prediction device for predicting a replacement time of a cleaning solution in a cleaning facility for an alkaline immersion degreasing process, the cleaning solution being provided with a cleaning tank for storing an alkaline solution cleaning solution to which a surfactant is added as necessary, a filter for removing impurities contained in the cleaning solution, and a circulation pump for circulating the cleaning solution between the cleaning tank and the filter,
a measurement value acquiring means for acquiring a pH value of the cleaning liquid successively measured by a sensor installed at a predetermined position in the cleaning tank together with a measurement time;
a change point extraction means for extracting a bottom side change point where a slope of a graph showing a change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive and a top side change point where a slope of the graph changes from positive to negative, the bottom side change point being obtained by arranging in chronological order the pH values of the cleaning liquid acquired by the measurement acquisition means after the cleaning liquid is introduced into the cleaning tank or replaced with another cleaning liquid;
a filter means for performing a filtering process for removing, for each bottom-side change point extracted by the change point extraction means, a measurement value between the bottom-side change point and the top-side change point extracted by the change point extraction means subsequent to the bottom-side change point from the graph;
a regression line calculation means for calculating a regression line from the graph on which the filtering process has been performed by the filtering means;
a predicted replacement time calculation means for calculating, by using the regression line calculated by the regression line calculation means, a time when the pH value of the cleaning liquid in the cleaning tank becomes a predetermined threshold value as a pH value that requires replacement of the cleaning liquid; and
and a predicted replacement time output means for outputting the predicted replacement time of the cleaning liquid calculated by the predicted replacement time calculation means.

In another aspect of the present invention, the pH value of the cleaning liquid is measured sequentially by a sensor installed at a predetermined position in the cleaning tank, the measured values are arranged in chronological order in the order of the measurement time, and a graph showing the change in the pH value of the cleaning liquid in the cleaning tank after the cleaning liquid is added or replaced is specified. Then, a bottom-side change point where the slope of the graph showing the change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive is extracted, and for each bottom-side change point, a filtering process is performed to remove the measured pH values higher than the bottom-side change point from the measured values included after this bottom-side change point to the next bottom-side change point after this bottom-side change point. Then, a regression line is obtained from the graph after the filtering process, and the regression line is used to calculate the time when the pH value of the cleaning liquid in the cleaning tank will reach a predetermined threshold value as a pH value that requires replacement of the cleaning liquid, and this calculated time is output as a predicted value for the time to replace the cleaning liquid.

For example, another aspect of the present invention is
A cleaning solution replacement prediction device for predicting a replacement time of a cleaning solution in a cleaning facility for an alkaline immersion degreasing process, the cleaning solution being provided with a cleaning tank for storing an alkaline solution cleaning solution to which a surfactant is added as necessary, a filter for removing impurities contained in the cleaning solution, and a circulation pump for circulating the cleaning solution between the cleaning tank and the filter,
a measurement value acquiring means for acquiring a pH value of the cleaning liquid successively measured by a sensor installed at a predetermined position in the cleaning tank together with a measurement time;
a change point extraction means for extracting a bottom side change point at which a slope of a graph showing a change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive, the change point being obtained by arranging in chronological order the pH values of the cleaning liquid acquired by the measurement acquisition means after the cleaning liquid is introduced into the cleaning tank or after the cleaning liquid is replaced;
a filter means for performing a filtering process for removing from the graph, for each bottom-side change point extracted by the change point extraction means, a measured pH value higher than the bottom-side change point among measured values included after the bottom-side change point and up to the next bottom-side change point of the bottom-side change point;
a regression line calculation means for calculating a regression line from the graph on which the filtering process has been performed by the filtering means;
a predicted replacement time calculation means for calculating, by using the regression line calculated by the regression line calculation means, a time when the pH value of the cleaning liquid in the cleaning tank becomes a predetermined threshold value as a pH value that requires replacement of the cleaning liquid; and
and a predicted replacement time output means for outputting the predicted replacement time of the cleaning liquid calculated by the predicted replacement time calculation means.

The inventors discovered that in cleaning equipment for cleaning processes such as alkaline immersion degreasing, the pH value of the alkaline solution stored in the cleaning tank decreases when the equipment is in operation, but increases when the equipment is not in operation. Furthermore, they discovered that by repeatedly switching between operation and non-operation, the pH value gradually decreases overall over time, repeating cycles of decrease and increase.

In one aspect of the present invention, the pH values of the cleaning liquid measured successively after the cleaning liquid is added or replaced by a sensor installed at a predetermined position in the cleaning tank are arranged in chronological order according to the measurement time to identify a graph showing the progress of the pH value of the cleaning liquid in the cleaning tank, and the bottom side change point and the top side change point of this graph are extracted. Then, a filtering process is performed to remove the measured values between the bottom side change point and the top side change point, which are arranged in the order of the bottom side change point, the top side change point, and a regression line is obtained from the graph after the filtering process to predict the time to replace the cleaning liquid.

In another aspect of the present invention, the pH values of the cleaning liquid measured successively after the cleaning liquid is added or replaced by a sensor installed at a predetermined position in the cleaning tank are arranged in chronological order according to the measurement time to identify a graph showing the progress of the pH value of the cleaning liquid in the cleaning tank, and bottom-side change points of this graph are extracted. Then, for each bottom-side change point extracted, a filtering process is performed to remove measurement points with a higher pH value than the bottom-side change point from the measurement values included after this bottom-side change point to the next bottom-side change point of this bottom-side change point, and a regression line is obtained from the graph after the filtering process to predict the time to replace the cleaning liquid.

In this way, it is possible to obtain a regression line from a graph showing the change in the pH value of the cleaning liquid in the cleaning tank, after removing the pH values with large noise components when the cleaning equipment is not in operation, and to predict when to replace the cleaning liquid in the cleaning tank. Therefore, according to the present invention, it is possible to predict with high accuracy when to replace the alkaline solution used in cleaning processes such as alkaline immersion degreasing. In addition, since the sensor installed at a predetermined position in the cleaning tank can be operated at all times regardless of whether the cleaning equipment is in operation or not, there is no impact on the maintenance of the cleaning equipment.

FIG. 1 is a schematic diagram of a cleaning liquid replacement prediction system 1 according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the transition of the pH value of the cleaning liquid 60 stored in the cleaning tank 61. As shown in FIG. FIG. 3 is a diagram for explaining the principle of how the cleaning liquid replacement prediction device 3 predicts the replacement time of the cleaning liquid 60. As shown in FIG. FIG. 4 is a schematic functional configuration diagram of the cleaning liquid replacement prediction device 3. As shown in FIG. FIG. 5 is a flowchart for explaining the predicted replacement time calculation process of the cleaning liquid replacement prediction device 3. FIG. 6 is a flowchart for explaining the pH value stabilization standby time setting process of the cleaning liquid replacement prediction device 3. FIG. 7 is a diagram for explaining the principle of predicting the replacement time of the cleaning fluid 60 by a modified example of the cleaning fluid replacement prediction device 3. As shown in FIG.

Below, one embodiment of the present invention will be described with reference to the drawings. Here, we will use an example in which the present invention is applied to an alkaline immersion degreasing treatment facility.

Figure 1 is a schematic diagram of a cleaning fluid replacement prediction system 1 according to this embodiment.

The cleaning liquid replacement prediction system 1 according to the present embodiment predicts the replacement timing of the cleaning liquid 60 in the alkaline immersion degreasing equipment 6.

Here, the alkaline immersion degreasing equipment 6 includes a cleaning tank 61 in which the cleaning liquid 60 is stored, a filter 62 that removes impurities contained in the cleaning liquid 60, and a circulation of the cleaning liquid 60 between the cleaning tank 61 and the filter 62. It includes a circulation pump 63 and a nozzle 64 that injects a part of the cleaning liquid 60 supplied to the cleaning tank 61 by the circulation pump 63 into the cleaning tank 61. In FIG. 1, the cleaning liquid 60 supplied to the cleaning tank 61 by the circulation pump 63 is divided into a system in which the cleaning liquid 60 is injected into the cleaning tank 61 from the nozzle 64 and a system in which it is supplied into the cleaning tank 61 without going through the nozzle 64. Although the system is branched into two supply systems, it is sufficient that at least one system is provided. Further, as the cleaning liquid 60, an alkaline solution cleaning liquid to which a surfactant is added as necessary is used. An example of such an alkaline cleaning solution is the "Nicca Sun Clean L Series" manufactured by NICCA CHEMICAL CO., LTD.

During operation of the alkaline immersion degreasing equipment 6, the cleaning liquid 60 stored in the cleaning tank 61 is drawn out from the cleaning tank 61 by the circulation pump 63, impurities are removed by the filter 62, and then returned to the cleaning tank 61. Therefore, the cleaning liquid 60 in the cleaning tank 61 is stirred, and the pH value of the cleaning liquid 60 in the cleaning tank 61 becomes uniform. On the other hand, when the alkali immersion degreasing equipment 6 is not in operation, the circulation pump 63 is stopped, so the cleaning liquid 60 in the cleaning tank 61 is not stirred, and the pH value of the cleaning liquid 60 in the cleaning tank 61 becomes uneven. .

The cleaning liquid replacement prediction system 1 is provided with a pH sensor 2 that is installed at a predetermined position in the cleaning tank 61 and sequentially measures the pH value of the cleaning liquid 60 stored in the cleaning tank 61 and sequentially outputs the measured value with the measurement time added, a cleaning liquid replacement prediction device 3, and an operation terminal 4 for operating the cleaning liquid replacement prediction device 3.

The cleaning fluid replacement prediction device 3 and the operation terminal 4 are connected to a network 50 such as a LAN (Local Area Network). The pH sensor 2 is also connected to the network 50 via a wireless communication device 51 and a wireless AP (Access Point) 52. The wireless communication device 51 sequentially transmits the measurement values sequentially output from the pH sensor 2 to the cleaning fluid replacement prediction device 3 via the wireless AP 52 and the network 50. Note that instead of the wireless communication device 51, a communication device that connects the pH sensor 2 to the network 50 by wired communication may be used.

The cleaning liquid replacement prediction device 3 receives the measured values sequentially output from the pH sensor 2 from the wireless communication device 51, and predicts the replacement timing of the cleaning liquid 60 stored in the cleaning tank 61 based on the measured values. Then, the prediction result is transmitted to the operating terminal 4 and displayed.

The present inventor discovered that, as shown in FIG. 2, the pH value of the cleaning liquid 60 in the cleaning tank 61 decreases (reference numeral 10) while the alkaline immersion degreasing treatment equipment 6 is in operation; It was found that it increases (code 11) during non-operation. By repeating the operation and non-operation of the alkaline immersion degreasing equipment 6, the pH value of the cleaning liquid 60 in the cleaning tank 61 repeats a cycle of decreasing and increasing, gradually decreasing as a whole over time. I found out that it works (code 12).

Therefore, in the cleaning liquid replacement prediction device 3, as shown in FIG. are arranged in chronological order to identify the graph 13 that represents the change in the pH value of the cleaning liquid 60 since it was added or replaced, and the point where the sign of the slope of this graph 13 changes (the bottom side change point where the slope changes from negative to positive) 14 and the top side change point 15) where the slope changes from positive to negative are extracted. Then, between the bottom side change point 14 and the top side change point 15 that appears next to this bottom side change point 14 (the bottom side change point 14 and the adjacent bottom side change point 15 in the order of the bottom side change point 14 and the top side change point 15) The measured value between the top side change point 15, that is, the section where the slope is positive (measured value when the alkaline immersion degreasing treatment equipment 6 is not in operation), and the pH value stabilization waiting time from the top side change point 15 ( The time required for the cleaning liquid 60 in the cleaning tank 61 to be sufficiently stirred and the pH value to become uniform after the alkali immersion degreasing equipment 6 starts operating) A filtering process is performed to remove the measured values included in the period t. do. Then, a regression line 16 is obtained from the graph 13 after the filtering process (the graph 13 from which the measured values in the broken line portion have been removed), and using this regression line 16, the pH value of the cleaning liquid 60 in the cleaning tank 61 is determined by the cleaning liquid 60. The time when the pH value reaches a predetermined threshold value 17 that requires replacement of the cleaning liquid 60 is calculated, and this time is set as the predicted replacement time of the cleaning liquid 60.

FIG. 4 is a schematic functional configuration diagram of the cleaning liquid replacement prediction device 3. As shown in FIG.

As shown in the figure, the cleaning liquid replacement prediction device 3 has a network interface unit 300, a measurement value acquisition unit 301, a measurement value storage unit 302, an operation reception unit 303, a change point extraction unit 304, a filter unit 305, a regression line calculation unit 306, a replacement prediction time calculation unit 307, a pH value stabilization waiting time calculation unit 308, and a main control unit 309.

The network interface section 300 is an interface for connecting to the network 50.

The measured value acquisition unit 301 acquires the measured values (in the cleaning tank 61 pH value of the cleaning liquid 60) is acquired via the network interface unit 300.

The measurement value storage unit 302 stores the measurement values with the measurement time sequentially output from the pH sensor 2 acquired by the measurement value acquisition unit 301.

The operation reception unit 303 receives various operations from the operation terminal 4 via the network interface unit 300, including a replacement time prediction operation and a pH value stabilization standby time setting operation. Then, the processing result of the received operation is transmitted to the operation terminal 4 as necessary.

The change point extraction unit 304 identifies a graph 13 (a graph 13 in which multiple measured values output by the pH sensor 2 are arranged in chronological order according to the measurement times added to these measured values) that represents the change in the pH value of the cleaning solution 60 in the cleaning tank 61 during a period specified by the replacement timing prediction operation or the pH value stabilization waiting time setting operation received by the operation reception unit 303 from the operation terminal 4, and extracts a bottom side change point 14 where the slope of this graph 13 changes from negative to positive and a top side change point 15 where the slope changes from positive to negative (see FIG. 3).

The filter unit 305 uses the identification results obtained by the change point extraction unit 304 (graph 13 representing the transition of the pH value of the cleaning liquid 60 in the cleaning tank 61, the bottom side change point 14, and the top side change point 15) and the pH value stabilization. According to the pH value stabilization waiting time t calculated by the waiting time calculation unit 308, the difference between the bottom side changing point 14 and the top side changing point 15 that appears next to this bottom side changing point 14 (bottom side changing point 14 , the measured value between the bottom side change point 14 and the top side change point 15 that are chronologically adjacent to the top side change point 15), and the period of pH value stabilization waiting time t from the top side change point 15. A filtering process is performed to remove the measured values included in (see FIG. 3).

The regression line calculation unit 306 calculates the regression line 16, for example, by the least squares method, using the multiple measurement values that constitute the graph 13 after filtering processing by the filter unit 305.

The predicted replacement time calculation unit 307 uses the regression line 16 calculated by the regression line calculation unit 306 to calculate the time when the pH value of the cleaning liquid 60 in the cleaning tank 61 will reach a predetermined threshold value 17 as a pH value that requires replacement of the cleaning liquid 60, as the predicted replacement time for the cleaning liquid 60 (see Figure 3).

The pH value stabilization waiting time calculation unit 308 cooperates with the change point extraction unit 304, the filter unit 305, the regression line calculation unit 306, and the predicted replacement time calculation unit 307 to calculate the cleaning liquid calculated by the predicted replacement time calculation unit 307. 60 and the actual replacement time specified in the pH value stabilization standby time setting operation received from the operation terminal 4 by the operation reception unit 303 is within a predetermined range. Calculate the time.

The main control unit 309 comprehensively controls each of the units 300 to 308 of the cleaning liquid replacement prediction device 3.

The functional configuration of the cleaning liquid replacement prediction device 3 shown in Figure 4 may be realized in hardware using an integrated logic IC such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), or may be realized in software using a computer such as a DSP (Digital Signal Processor). Alternatively, it may be realized by a general-purpose computer such as a PC (Personal Computer) that includes a CPU (Central Processing Unit), memory, an auxiliary storage device such as a HDD (Hard Disk Drive) or SSD (Solid State Drive), and a communication interface such as a NIC (Network Interface Card), where the CPU loads a specific program from the auxiliary storage device into the memory and executes it.

Figure 5 is a flow diagram for explaining the predicted replacement time calculation process of the cleaning liquid replacement prediction device 3. This flow starts when the operation reception unit 303 receives a replacement time prediction operation that includes specification of the latest replacement time or input time of the cleaning liquid 60 stored in the cleaning tank 61 from the operation terminal 4 via the network interface unit 300.

First, the operation reception unit 303 notifies the main control unit 309 of the latest replacement time or input time specified in the replacement time prediction operation and requests calculation of the predicted replacement time. In response to this, the main control unit 309 checks whether the pH value stabilization standby time t has been set (S100). If the pH value stabilization standby time t has not been set (NO in S100), the main control unit 309 notifies the operation reception unit 303 to that effect. In response to this, the operation reception unit 303 sends a message to the operation terminal 4 via the network interface unit 300 to the effect that it is necessary to perform the pH value stabilization waiting time calculation process prior to the replacement predicted time calculation process. A predetermined error process such as error processing is performed (S107).

On the other hand, if the pH value stabilization standby time t has already been set (YES in S100), the main control unit 309 stores the latest replacement time or input time received from the operation reception unit 303 from the measured value storage unit 302. A plurality of measured values (pH value of the cleaning liquid 60 in the cleaning tank 61) with measurement times added are read (S101). Then, the main control unit 309 passes the plurality of measured values read from the measured value storage unit 302 to the change point extraction unit 304 and instructs it to extract a change point. In response to this, the change point extraction unit 304 extracts a plurality of measurement values to which measurement times after the latest replacement time or input time are added, as shown in FIG. A graph 13 representing the change in pH value of the cleaning liquid 60 in the cleaning tank 61 after replacement or addition after being arranged in chronological order according to the time is specified, and a bottom side change point 14 and a top side change point 15 are extracted from this graph 13. (S102).

Next, the main control unit 309 passes the graph 13 identified by the change point extraction unit 304, the bottom side change point 14 and the top side change point 15 extracted by the change point extraction unit 304, and the set pH value stabilization waiting time t to the filter unit 305 to instruct the filtering process. In response to this, the filter unit 305 performs a filtering process to remove the measurement values (measurements when the alkaline immersion degreasing treatment equipment 6 is not in operation) between the bottom side change point 14 and the top side change point 15 that appears next to the bottom side change point 14 (between the bottom side change point 14 and the top side change point 15 that are adjacent in time series in the order of the bottom side change point 14 and the top side change point 15), as shown in FIG. 3, and the measurement values included in the period from the top side change point 15 to the pH value stabilization waiting time t (measurements belonging to the time period from when the alkaline immersion degreasing treatment equipment 6 starts operating until the cleaning solution 60 in the cleaning tank 61 is sufficiently stirred and the pH value becomes uniform) (S103).

Next, the main control unit 309 passes the graph 13 after filtering by the filter unit 305 (graph 13 from which the measurement values between the bottom side change point 14 and the top side change point 15, which are adjacent in time series in the order of the bottom side change point 14 and the top side change point 15, and the measurement values included in the period from the top side change point 15 to the pH value stabilization waiting time t have been removed) to the regression line calculation unit 306, and instructs it to calculate a regression line. In response to this, the regression line calculation unit 306 calculates the regression line 16, for example, by the least squares method, using the multiple measurement values constituting the graph 13 after filtering by the filter unit 305, as shown in FIG. 3 (S104).

Next, the main control unit 309 passes the regression line 16 calculated by the regression line calculation unit 306 to the predicted replacement time calculation unit 307 and instructs it to calculate the predicted replacement time. In response to this, the predicted replacement time calculation unit 307 uses the regression line 16 calculated by the regression line calculation unit 306, as shown in FIG. The time at which the pH value reaches a predetermined threshold value 17 that requires replacement is calculated as the predicted replacement time for the cleaning liquid 60 (S105).

Next, the main control unit 309 passes the predicted replacement time of the cleaning liquid 60 calculated by the predicted replacement time calculation unit 307 to the operation reception unit 303. In response to this, the operation reception unit 303 transmits the predicted replacement time of the cleaning liquid 60 received from the main control unit 309 to the operation terminal 4 via the network interface unit 300 (S106).

Figure 6 is a flow diagram for explaining the pH value stabilization waiting time setting process of the cleaning liquid replacement prediction device 3. This flow starts when the operation reception unit 303 receives a pH value stabilization waiting time setting operation from the operation terminal 4 via the network interface unit 300, which includes specification of the most recent replacement time of the cleaning liquid 60 stored in the cleaning tank 61 and the replacement time just before that (only the most recent replacement time if the most recent replacement time is the first replacement time).

First, the operation reception unit 303 notifies the main control unit 309 of the latest replacement time and the replacement time just before (only the latest replacement time if the latest replacement time is the first time) specified in the pH value stabilization waiting time setting operation, and requests the calculation of the pH value stabilization waiting time. In response to this, the main control unit 309 reads from the measurement value storage unit 302 a plurality of measurement values (pH values of the cleaning solution 60 in the cleaning tank 61) to which the measurement time between the latest replacement time and the replacement time just before (before the latest replacement time if only the latest replacement time) received from the operation reception unit 303 is added (S110). In addition, the main control unit 309 notifies the pH value stabilization waiting time calculation unit 308 of the latest replacement time specified in the pH value stabilization waiting time setting operation, and instructs the calculation of the pH value stabilization waiting time. In response to this, the pH value stabilization waiting time calculation unit 308 sets the provisional pH value stabilization waiting time t' to "0" and the previous time difference to an initial value (for example, the value S used in S116) (S111).

Next, the main control unit 309 passes the multiple measured values read from the measured value storage unit 302 to the change point extraction unit 304, instructing it to extract change points. In response to this, the change point extraction unit 304, similar to S102 of the predicted replacement timing calculation process described above, arranges the multiple measured values to which the measurement times received from the main control unit 309 are added in chronological order according to the measurement times added to these measured values, identifies a graph 13 that represents the change in the pH value of the cleaning solution 60 in the cleaning tank 61 during the period between the most recent replacement time and the replacement time just before that, and extracts a bottom side change point 14 where the slope of this graph 13 changes from negative to positive and a top side change point 15 where the slope changes from positive to negative (S112).

Then, the main control unit 309 sends the filter unit 305 the graph 13 specified by the change point extraction unit 304, the bottom side change point 14 and the top side change point 15 extracted by the change point extraction unit 304, and the temporary pH value. The filtering process is instructed by passing the value stabilization waiting time t'. In response to this, the filter unit 305, similarly to S103 of the above-mentioned replacement prediction time calculation process, performs a filtering process between each bottom-side change point 14 and the next top-side change point 15 (bottom-side change point 14, Measured values between the bottom-side change point 14 and the top-side change point 15 that are chronologically adjacent to the top-side change point 15), and the measured values within the temporary pH value stabilization waiting time t' from the top-side change point 15 A filtering process is performed to remove the measured values included in (S113).

Next, the main control unit 309 sends the regression line calculation unit 306 to the graph 13 after the filtering process by the filter unit 305 (bottom side change points adjacent in time series in the order of bottom side change point 14 and top side change point 15). The regression line is calculated by passing the measured values between 14 and the top side change point 15 and the graph 13) in which the measured values included within the temporary pH value stabilization waiting time t' from the top side change point 15 are removed. instruct. In response to this, the regression line calculation unit 306 uses, for example, the least squares method, using the plurality of measured values that constitute the graph 13 after the filtering process by the filter unit 305, similar to S104 of the above-mentioned replacement predicted time calculation process. A regression line 16 is calculated (S114).

Then, the main control unit 309 passes the regression line 16 calculated by the regression line calculation unit 306 to the predicted replacement time calculation unit 307 and instructs it to calculate the predicted replacement time. In response to this, the predicted replacement time calculation unit 307 uses the regression line 16 calculated by the regression line calculation unit 306 to adjust the cleaning liquid 60 in the cleaning tank 61, similarly to S105 of the predicted replacement time calculation process described above. The time when the pH value reaches a predetermined threshold value 17 as a pH value that requires replacement of the cleaning liquid 60 is calculated as the predicted replacement time T of the cleaning liquid 60 (S115).

Next, the main control unit 309 notifies the pH value stabilization waiting time calculation unit 308 of the predicted replacement time T calculated by the predicted replacement time calculation unit 307. In response to this, the pH value stabilization waiting time calculation unit 308 calculates the time difference between the predicted replacement time T calculated by the predicted replacement time calculation unit 307 and the latest replacement time T0 specified in the pH value stabilization waiting time setting operation, and checks whether this time difference (T-T0) is within a predetermined range (for example, -S<T-T0<S) (S116). Then, if this time difference is not within the predetermined range (NO in S116), the pH value stabilization waiting time calculation unit 308 adds a predetermined value a to the provisional pH value stabilization waiting time t', sets this added value (t'+a) as a new provisional pH value stabilization waiting time t' (S118), and returns to step S113.

If the time difference is within a predetermined range (YES in S116), or if the time difference is smaller than the time difference calculated previously (YES in S117), the pH value stabilization waiting time calculation unit 308 adds a predetermined value a to the provisional pH value stabilization waiting time t', sets this added value (t'+a) as a new provisional pH value stabilization waiting time t' (S118), and returns to step S113. On the other hand, if the time difference is the same as the time difference calculated previously or has increased (NO in S117), the pH value stabilization waiting time calculation unit 308 sets the value obtained by subtracting the predetermined value a from the provisional pH value stabilization waiting time t' as the pH value stabilization waiting time t, which is the time required for the cleaning solution 60 in the cleaning tank 61 to be sufficiently stirred and the pH value to become uniform after the alkaline immersion degreasing treatment equipment 6 is started (S119).

The above describes one embodiment of the present invention.

As described above, the present inventor discovered that, as shown in FIG. It has been found that when the degreasing equipment 6 is not in operation, it increases (symbol 11). By repeating the operation and non-operation of the alkaline immersion degreasing equipment 6, the pH value of the cleaning liquid 60 in the cleaning tank 61 repeats a cycle of decreasing and increasing, gradually decreasing as a whole over time. I found out that it works (code 12).

In this embodiment, as shown in FIG. 3, the pH values of the cleaning liquid 60 measured sequentially after replacement or introduction of the cleaning liquid 60 by the pH sensor 2 installed at a predetermined position in the cleaning tank 61 are arranged in a chronological order to identify a graph 13 showing the change in the pH value of the cleaning liquid 60 after replacement or introduction, and a bottom side change point 14 and a top side change point 15 are extracted from this graph 13. Then, a filtering process is performed to remove the measured values between the bottom side change point 14 and the top side change point 15 arranged in the order of the bottom side change point 14 and the top side change point 15 in the time axis direction, and a regression line 16 is obtained from the filtered graph 13. Furthermore, using this regression line 16, the time when the pH value of the cleaning liquid 60 in the cleaning tank 61 will reach a predetermined threshold value 17 as a pH value requiring replacement of the cleaning liquid 60 is calculated as the predicted replacement time of the cleaning liquid 60.

As described above, in the present embodiment, from the graph 13 representing the transition of the pH value of the cleaning liquid 60 in the cleaning tank 61, the pH values with large noise components when the alkaline immersion degreasing equipment 6 is not in operation are excluded. Since the regression line 16 can be determined and the time to replace the cleaning liquid 60 can be predicted, the time to replace the cleaning liquid 60 in the cleaning tank 61 can be predicted with high accuracy. Furthermore, since the pH sensor 2 installed at a predetermined position in the cleaning tank 61 can be operated at all times regardless of whether the alkaline immersion degreasing equipment 6 is in operation or not, maintenance of the alkaline immersing degreasing equipment 6 is not affected.

In the present embodiment, in the filtering process, as shown in FIG. 3, in addition to the measurement values between the bottom-side change point 14 and the top-side change point 15, which are adjacent to each other in the order of the bottom-side change point 14 and the top-side change point 15, the measurement values included in the period from the top-side change point 15 to the pH value stabilization waiting time t are also removed from the graph 13 showing the change in the pH value of the cleaning liquid 60 in the cleaning tank 61. Therefore, the regression line 16 can be obtained from the graph 13 showing the change in the pH value of the cleaning liquid 60 in the cleaning tank 61 by excluding the pH values with large noise components from the time when the alkaline immersion degreasing treatment equipment 6 is operated until the cleaning liquid 60 in the cleaning tank 61 is sufficiently stirred and the pH value becomes uniform, so that the time to replace the cleaning liquid 60 in the cleaning tank 61 can be predicted with higher accuracy.

In addition, in this embodiment, the provisional pH value stabilization waiting time t' is used to calculate the predicted replacement time of the cleaning liquid 60, and the provisional pH value stabilization waiting time t' is changed until the time difference between the calculated predicted replacement time of the cleaning liquid 60 and the actual replacement time of the cleaning liquid 60 falls within a predetermined range, and the provisional pH value stabilization waiting time t' at which this time difference falls within the predetermined range is set as the pH value stabilization waiting time t. Therefore, the pH value stabilization waiting time t, which is the time from when the alkaline immersion degreasing treatment equipment 6 starts operating until the cleaning liquid 60 in the cleaning tank 61 is sufficiently agitated and the pH value becomes uniform, can be set more accurately.

The present invention is not limited to the above-described embodiment, and many variations are possible within the scope of the invention.

For example, in the cleaning liquid replacement prediction device 3, the filter unit 305 performs filtering processing for all top side change points 15 extracted by the change point extraction unit 304 by commonly using the pH value stabilization waiting time t calculated by the pH value stabilization waiting time calculation unit 308 as the pH value stabilization waiting time t starting from the top side change point 15. However, the present invention is not limited to this. The pH value stabilization waiting time t starting from the top side change point 15 may be changed for each top side change point 15 extracted by the change point extraction unit 304.

For example, in the pH value stabilization waiting time setting process shown in FIG. 6, for each top side change point 15 extracted by S112, the increase value h from the bottom side change point 14 extracted immediately before the top side change point 15 to this top side change point 15 is calculated (see FIG. 3), and the average value of these is set as the standard increase value hs, and the pH value stabilization waiting time t set in S119 is set as the standard pH value stabilization waiting time ts.

Next, in the replacement predicted time calculation process of FIG. 5, for each top side change point 15 extracted in S102, from the bottom side change point 14 extracted immediately before the top side change point 15 to this top side change point 15 The increase value h is determined (see FIG. 3), and the determined increase value h is linked to this top-side change point 15. Then, in S103, for each top-side change point 15 extracted by the change-point extractor 304, the filter unit 305 converts the reference pH value stabilization waiting time ts to the increase value h linked to the top-side change point 15. The value corrected by the ratio h/hs between the reference increase value hs and the reference increase value hs (t=ts (h/hs)) is used as the pH value stabilization waiting time t starting from the top side change point 15, and the filtering process is performed. implement.

Alternatively, in the pH value stabilization waiting time setting process shown in FIG. 6, for each top side change point 15 extracted by S112, the elapsed time m from the bottom side change point 14 extracted immediately before the top side change point 15 to this top side change point 15 is calculated (see FIG. 3), and the average value of these is set as the reference elapsed time ms, and the pH value stabilization waiting time t set in S119 is set as the reference pH value stabilization waiting time ts.

5, for each top-side change point 15 extracted by S102, the elapsed time m from the bottom-side change point 14 extracted immediately before the top-side change point 15 to this top-side change point 15 is calculated (see FIG. 3), and the calculated elapsed time m is linked to this top-side change point 15. Then, in S103, the filter unit 305 performs filtering processing for each top-side change point 15 extracted by the change point extraction unit 304, using the value (t = ts (m/ms)) obtained by correcting the reference pH value stabilization waiting time ts by the ratio m/ms of the elapsed time m linked to the top-side change point 15 and the reference elapsed time ms as the pH value stabilization waiting time t starting from the top-side change point 15.

The inventor has discovered that the longer the period in which the cleaning liquid 60 stored in the cleaning tank 61 is not stirred (the non-operating period of the alkaline immersion degreasing equipment 6), the higher the pH value of the cleaning liquid 60 in the cleaning tank 61, and the more the alkali It has been found that the time required for the cleaning liquid 60 in the cleaning tank 61 to be sufficiently agitated and the pH value of the cleaning liquid 60 in the cleaning tank 61 to become uniform after the immersion degreasing equipment 6 starts operating is found to be long.

Therefore, as described above, in the filtering process, for each top-side change point 15 extracted from the graph 13 showing the change in the pH value of the cleaning liquid 60 in the cleaning tank 61, the pH value stabilization waiting time t starting from the top-side change point 15 is set to the standard pH value stabilization waiting time ts, which is corrected by the ratio h/hs of the increase value h from the bottom-side change point 14 extracted immediately before the top-side change point 15 to the top-side change point 15 to the standard increase value hs (t = ts (h/hs)), or by the ratio m/ms of the elapsed time m from the bottom-side change point 14 extracted immediately before the top-side change point 15 to the top-side change point 15 to the standard elapsed time ms (t = ts (m/ms)). This makes it possible to more reliably exclude pH values with large noise components from the time when the alkaline immersion degreasing treatment equipment 6 starts operating until the cleaning liquid 60 in the cleaning tank 61 is sufficiently agitated and the pH value of the cleaning liquid 60 in the cleaning tank 61 becomes uniform. This makes it possible to predict with greater accuracy when to replace the cleaning solution 60 in the cleaning tank 61.

In addition, in the cleaning liquid replacement prediction device 3, the filter unit 305 performs a filtering process to remove, from the graph 13 showing the change in the pH value of the cleaning liquid 60 in the cleaning tank 61, the measurement values between the bottom side change point 14 and the top side change point 15, which are adjacent to each other in the order of the bottom side change point 14 and the top side change point 15, as well as the measurement values included in the period from the top side change point 15 to the pH value stabilization waiting time t, as shown in FIG. 3. However, the present invention is not limited to this.

For example, as shown in FIG. 7, in the graph 13 showing the change in the pH value of the cleaning solution 60 in the cleaning tank 61, the filter unit 305 may perform a filtering process for each bottom-side change point 14 to remove measurement values having a higher pH value than the pH value x of the bottom-side change point 14 (measurement values in the dashed line portion) from the measurement values included after this bottom-side change point 14 to the bottom-side change point 14 next to this bottom-side change point 14.

Even in this case, the regression line 16 can be obtained by excluding the pH value with a large noise component, including the pH value measured while the alkaline immersion degreasing treatment equipment 6 is not in operation, from the graph 13 showing the change in the pH value of the cleaning liquid 60 in the cleaning tank 61, so that the replacement time of the cleaning liquid 60 in the cleaning tank 61 can be predicted with high accuracy using this regression line 16. In this case, the change point extraction unit 304 only needs to extract the bottom side change point 14 from the graph 13 showing the change in the pH value of the cleaning liquid 60 in the cleaning tank 61. In addition, since the pH value stabilization waiting time t is not used in the filtering process, S100 and S107 of the replacement prediction time calculation process shown in FIG. 5 and the pH value stabilization time waiting process shown in FIG. 6 are not required. Therefore, the pH value stabilization waiting time calculation unit 308 can be omitted, and the configuration of the cleaning liquid replacement prediction device 3 can be simplified.

Further, in the above embodiment, the measured value acquisition unit 301 and the measured value storage unit 302 are omitted from the cleaning liquid replacement prediction device 3, and the measured value acquisition unit 301 and the measured value storage unit are provided separately from the cleaning liquid replacement prediction device 3. A database including 302 may be provided. In the cleaning liquid replacement prediction device 3, the main control unit 309 may access the database via the network interface unit 300 and obtain necessary measured values from the measured value storage unit 302. Further, the cleaning liquid replacement prediction device 3 may be integrated with the operation terminal 4.

1: Cleaning liquid replacement prediction system 2: pH sensor 3: Cleaning liquid replacement prediction device 4: Operation terminal 6: Alkaline immersion degreasing treatment equipment 50: Network 51: Wireless communication device 52: Wireless AP 60: Cleaning liquid 61: Cleaning tank 62: Filter 63: Circulation pump 64: Nozzle 300: Network interface unit 301: Measurement value acquisition unit 302: Measurement value storage unit 303: Operation reception unit 304: Change point extraction unit 305: Filter unit 306: Regression line calculation unit 307: Replacement prediction timing calculation unit 308: pH value stabilization waiting time calculation unit 309: Main control unit

Claims (10)

A cleaning solution replacement prediction device for predicting a replacement time of a cleaning solution in a cleaning facility for an alkaline immersion degreasing process, the cleaning solution being provided with a cleaning tank for storing an alkaline solution cleaning solution to which a surfactant is added as necessary, a filter for removing impurities contained in the cleaning solution, and a circulation pump for circulating the cleaning solution between the cleaning tank and the filter,
a measurement value acquiring means for acquiring a pH value of the cleaning liquid successively measured by a sensor installed at a predetermined position in the cleaning tank together with a measurement time;
a change point extraction means for extracting a bottom side change point where a slope of a graph showing a change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive and a top side change point where a slope of the graph changes from positive to negative, the bottom side change point being obtained by arranging in chronological order the pH values of the cleaning liquid acquired by the measurement acquisition means after the cleaning liquid is introduced into the cleaning tank or replaced with another cleaning liquid;
a filter means for performing a filtering process for removing, for each bottom-side change point extracted by the change point extraction means, a measurement value between the bottom-side change point and the top-side change point extracted by the change point extraction means subsequent to the bottom-side change point from the graph;
a regression line calculation means for calculating a regression line from the graph on which the filtering process has been performed by the filtering means;
a predicted replacement time calculation means for calculating, by using the regression line calculated by the regression line calculation means, a time when the pH value of the cleaning liquid in the cleaning tank becomes a predetermined threshold value as a pH value that requires replacement of the cleaning liquid; and
and a predicted replacement time output means for outputting the predicted replacement time of the cleaning liquid calculated by the predicted replacement time calculation means. 2. The cleaning liquid replacement prediction device according to claim 1,
The filter means comprises:
and in the filtering process, for each of the top side change points extracted by the change point extraction means, also removing from the graph the measurement values included in the period from the top side change point to a predetermined pH value stabilization waiting time. The cleaning liquid replacement prediction device according to claim 2,
pH value stabilization standby time determining means for determining the pH value stabilization standby time using the predicted replacement time of the cleaning liquid calculated by the predicted replacement time calculation means and the actual replacement time of the cleaning liquid. Furthermore, it has
The pH value stabilization waiting time determining means includes:
A preset provisional value is set as the pH value stabilization standby time, the predicted replacement time calculation means calculates the predicted replacement time of the cleaning liquid, and the calculated predicted replacement time of the cleaning liquid and the actual value of the cleaning liquid are calculated. The provisional value is changed until the time difference from the replacement time falls within a predetermined range, and the provisional value at which the time difference falls within a predetermined range is determined as the pH value stabilization waiting time. Prediction device. 4. The cleaning liquid replacement prediction device according to claim 3,
The pH value stabilization waiting time determining means
in the graph filtered by the filter means with the provisional value in which the time difference falls within a predetermined range as the pH value stabilization waiting time, for each top-side change point extracted by the change-point extraction means, an increase value from the bottom-side change point extracted immediately before the top-side change point to the top-side change point is calculated, and an average value of the increase values is set as a reference increase value;
The filter means comprises:
and correcting, for each of the top-side change points extracted by the change-point extraction means, the pH value stabilization waiting time following the top-side change point in accordance with a ratio of an increase value from the bottom-side change point extracted by the change-point extraction means immediately before the top-side change point to the top-side change point in question and the reference increase value. A cleaning solution replacement prediction device for predicting a replacement time of a cleaning solution in a cleaning facility for an alkaline immersion degreasing process, the cleaning solution being provided with a cleaning tank for storing an alkaline solution cleaning solution to which a surfactant is added as necessary, a filter for removing impurities contained in the cleaning solution, and a circulation pump for circulating the cleaning solution between the cleaning tank and the filter,
a measurement value acquiring means for acquiring a pH value of the cleaning liquid successively measured by a sensor installed at a predetermined position in the cleaning tank together with a measurement time;
a change point extraction means for extracting a bottom side change point at which a gradient of a graph showing a change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive, the graph being obtained by arranging in chronological order the pH values of the cleaning liquid acquired by the measurement acquisition means after the cleaning liquid is introduced into the cleaning tank or after the cleaning liquid is replaced, in the order of the measurement times;
a filter means for performing a filtering process for removing, from a graph showing a transition in the pH value of the cleaning liquid, measurement values having a higher pH value than the bottom-side change point among measurement values included in the period from the bottom-side change point to the next bottom-side change point after the bottom-side change point extracted by the change point extraction means;
a regression line calculation means for calculating a regression line from the graph on which the filtering process has been performed by the filtering means;
a predicted replacement time calculation means for calculating, by using the regression line calculated by the regression line calculation means, a time when the pH value of the cleaning liquid in the cleaning tank becomes a predetermined threshold value as a pH value that requires replacement of the cleaning liquid; and
and a predicted replacement time output means for outputting the predicted replacement time of the cleaning liquid calculated by the predicted replacement time calculation means. A cleaning tank that stores an alkaline cleaning solution to which a surfactant is added as necessary, a filter that removes impurities contained in the cleaning solution, and a circulation pump that circulates the cleaning solution between the cleaning tank and the filter. A cleaning liquid replacement prediction system for predicting the replacement timing of the cleaning liquid in cleaning equipment for alkaline immersion degreasing treatment , comprising:
A cleaning liquid replacement prediction device according to any one of claims 1 to 5,
a sensor that is installed at a predetermined position in the cleaning tank, sequentially measures the pH value of the cleaning liquid stored in the cleaning tank, and sequentially outputs a measurement value with a measurement time added;
A cleaning liquid replacement prediction system, comprising: a communication device that transmits the measurement values to which the measurement times are added, which are sequentially output from the sensor, to the cleaning liquid replacement prediction device. A cleaning solution replacement prediction method for predicting a replacement time of a cleaning solution in a cleaning facility for an alkaline immersion degreasing process, the cleaning solution being provided with a cleaning tank for storing an alkaline solution cleaning solution to which a surfactant is added as necessary, a filter for removing impurities contained in the cleaning solution, and a circulation pump for circulating the cleaning solution between the cleaning tank and the filter, comprising:
The pH value of the cleaning liquid is sequentially measured by a sensor installed at a predetermined position in the cleaning tank, and the pH value is acquired together with the measurement time.
extracting a bottom side change point where a slope of a graph showing a change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive and a top side change point where a slope of the graph changes from positive to negative, the bottom side change point being obtained by arranging in time series based on the measurement time the pH values of the cleaning liquid obtained after the cleaning liquid is introduced into the cleaning tank or after the cleaning liquid is replaced;
performing a filtering process for removing, for each of the extracted bottom-side transition points, measurement values between the bottom-side transition point and the top-side transition point extracted subsequently to the bottom-side transition point from the graph;
Calculating a regression line from the graph on which the filtering process has been performed;
a time when the pH value of the cleaning liquid in the cleaning tank will reach a predetermined threshold value as a pH value requiring replacement of the cleaning liquid in the cleaning tank, is calculated using the calculated regression line, and the time when the pH value of the cleaning liquid will reach a predetermined threshold value as a pH value requiring replacement of the cleaning liquid in the cleaning tank is calculated and output as a predicted time to replace the cleaning liquid. A cleaning solution replacement prediction method for predicting a replacement time of a cleaning solution in a cleaning facility for an alkaline immersion degreasing process, the cleaning solution being provided with a cleaning tank for storing an alkaline solution cleaning solution to which a surfactant is added as necessary, a filter for removing impurities contained in the cleaning solution, and a circulation pump for circulating the cleaning solution between the cleaning tank and the filter, comprising:
The pH value of the cleaning liquid is sequentially measured by a sensor installed at a predetermined position in the cleaning tank, and the pH value is acquired together with the measurement time.
extracting a bottom side change point at which a slope of a graph showing a change in the pH value of the cleaning liquid in the cleaning tank changes from negative to positive, the bottom side change point being obtained by arranging in time series based on the measurement time the pH values of the cleaning liquid obtained after the cleaning liquid is introduced into the cleaning tank or after the cleaning liquid is replaced;
performing a filtering process for removing from the graph, for each of the extracted bottom-side change points, measurement values having a higher pH value than the bottom-side change point among measurement values included after the bottom-side change point and the next bottom-side change point after the bottom-side change point;
Calculating a regression line from the graph on which the filtering process has been performed;
a time when the pH value of the cleaning liquid in the cleaning tank will reach a predetermined threshold value as a pH value requiring replacement of the cleaning liquid in the cleaning tank, is calculated using the calculated regression line, and the time when the pH value of the cleaning liquid will reach a predetermined threshold value as a pH value requiring replacement of the cleaning liquid in the cleaning tank is calculated and output as a predicted time to replace the cleaning liquid. A program executable on a computer,
The program causes the computer to
A cleaning tank that stores an alkaline cleaning solution to which a surfactant is added as necessary, a filter that removes impurities contained in the cleaning solution, and a circulation pump that circulates the cleaning solution between the cleaning tank and the filter. Function as a cleaning liquid replacement prediction device for predicting the replacement timing of the cleaning liquid in a cleaning equipment for alkaline immersion degreasing treatment, comprising:
The cleaning liquid replacement prediction device is configured to:
Measured value acquisition means for acquiring the pH value of the cleaning liquid sequentially measured by a sensor installed at a predetermined position in the cleaning tank, together with the measurement time;
A pH value of the cleaning liquid in the cleaning tank, which is obtained by arranging the pH values of the cleaning liquid acquired by the measurement value acquisition means in chronological order of the measurement time after the cleaning liquid is added to the cleaning tank or replaced. change point extraction means for extracting a bottom change point where the slope of a graph representing the transition of changes from negative to positive and a top change point where the slope changes from positive to negative;
For each bottom side change point extracted by the change point extraction means, measurement between the bottom side change point and the top side change point extracted by the change point extraction means following the bottom side change point. filter means for performing a filtering process to remove values from the graph;
regression line calculation means for calculating a regression line from the graph on which the filtering process has been performed by the filtering means;
Using the regression line calculated by the regression line calculation means, the time when the pH value of the cleaning liquid reaches a predetermined threshold value as a pH value that requires replacement of the cleaning liquid in the cleaning tank is determined. A program characterized in that the program functions as: a predicted replacement time calculation means for calculating a predicted replacement time for the cleaning liquid; and a predicted replacement time output means for outputting a predicted replacement time for the cleaning liquid calculated by the predicted replacement time calculation means. A program executable on a computer,
The program causes the computer to
A cleaning tank that stores an alkaline cleaning solution to which a surfactant is added as necessary, a filter that removes impurities contained in the cleaning solution, and a circulation pump that circulates the cleaning solution between the cleaning tank and the filter. Function as a cleaning liquid replacement prediction device for predicting the replacement timing of the cleaning liquid in a cleaning equipment for alkaline immersion degreasing treatment, comprising:
The cleaning liquid replacement prediction device is configured to:
Measured value acquisition means for acquiring the pH value of the cleaning liquid sequentially measured by a sensor installed at a predetermined position in the cleaning tank, together with the measurement time;
A pH value of the cleaning liquid in the cleaning tank, which is obtained by arranging the pH values of the cleaning liquid acquired by the measurement value acquisition means in chronological order of the measurement time after the cleaning liquid is added to the cleaning tank or replaced. change point extraction means for extracting a bottom side change point where the slope of a graph representing the transition of changes from negative to positive;
For each bottom side change point extracted by the change point extracting means, the bottom side change point is determined from the measured values included between the bottom side change point and the next bottom side change point after the bottom side change point. filter means for performing a filtering process to remove measured values of higher pH values from the graph;
regression line calculation means for calculating a regression line from the graph on which the filtering process has been performed by the filtering means;
Using the regression line calculated by the regression line calculation means, the time when the pH value of the cleaning liquid reaches a predetermined threshold value as a pH value that requires replacement of the cleaning liquid in the cleaning tank is determined . A program characterized in that the program functions as: a predicted replacement time calculation means for calculating a predicted replacement time for the cleaning liquid; and a predicted replacement time output means for outputting a predicted replacement time for the cleaning liquid calculated by the predicted replacement time calculation means.

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