Cutting fluid concentration measuring system and device

Abstract

The invention discloses a cutting fluid concentration measuring system and a cutting fluid concentration measuring device, and aims to provide a rapid, light and automatic concentration detection means so as to ensure the machining precision and control the production cost. By adopting a critical angle method as a main measurement principle, the system realizes accurate detection of the percentage of the emulsified oil in the cutting fluid. In the aspect of system design, a critical angle method is selected to design an overall scheme. A trapezoidal prism is designed to optimize the optical path length and the system volume. An FPGA platform is adopted in hardware circuit design, a light source and a linear array CMOS image sensor are combined, and optimization of sensor performance and waterproof stability of the structure are ensured. According to the software part, the system collects images through a CMOS and carries out noise filtering and smoothing processing, inflection points are extracted through a data processing algorithm, and the concentration of the cutting fluid is measured by calibrating a fitting curve. Meanwhile, temperature compensation is carried out by combining temperature sensor data, so that the measurement accuracy is improved.

Description

Technical Field

[0001] The invention belongs to the field of concentration measurement, in particular to a cutting fluid concentration measurement system and device. Background Art

[0002] During metalworking, cutting fluid concentration directly impacts machining efficiency and workpiece quality. Therefore, accurate and real-time monitoring of cutting fluid concentration is crucial for ensuring machining quality. Existing methods typically require manual sampling and chemical analysis to determine cutting fluid concentration, which is time-consuming and infeasible for online monitoring.

[0003] The refractive index of a liquid refers to the phenomenon in which light is deflected when it travels from a vacuum into a liquid, slowing its propagation speed. The refractive index (n) is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in the medium (v), i.e., n = c / v. The concentration of a liquid is typically referred to as the mass or number of moles of solute per unit volume of liquid. According to the Lorentz-Lorentz equation, also known as the Kramers-Kronig equation, the refractive index of a liquid is related to its molecular polarizability: (n²-1) / (n²+2) = 4π / 3Nα, where N is the number of molecules per unit volume and α is the molecular polarizability. When a solute is dissolved in a solvent, the refractive index of the solution changes with the solute concentration. This is because the addition of solute molecules changes the molecular polarizability of the solution, thereby affecting the refractive index. For dilute solutions, the refractive index can be assumed to be linearly related to concentration: n = n² + kC, where n² is the refractive index of the pure solvent, k is a constant related to the solute's properties, and C is the solution's concentration. For the concentration measurement of cutting fluid, measuring the refractive index of cutting fluid to indirectly measure its concentration is a feasible and effective method. Summary of the Invention

[0004] The purpose of the present invention is to provide an automated, high-precision cutting fluid concentration measurement system and device to address the problems existing in the above-mentioned prior art.

[0005] The technical solutions for achieving the purpose of the present invention are as follows: On the one hand, a cutting fluid concentration measurement system is provided, the system comprising an optical imaging module, a data acquisition module, and a communication and processing module;

[0006] The optical imaging module is used to perform optical imaging on the cutting fluid to be tested and transmit the imaging information to the data acquisition module;

[0007] The data acquisition module is used to collect the imaging data transmitted by the optical imaging module and the temperature information of the cutting fluid to be measured, and transmit them to the communication and processing module;

[0008] The communication and processing module is used to calculate the concentration value of the cutting fluid to be tested based on the received information.

[0009] Furthermore, the optical imaging module forms an image of the light-dark boundary based on the critical angle method principle, and the position of the image boundary line is related to the concentration of the cutting fluid.

[0010] Furthermore, the optical imaging module includes a light source, an optical system and an image sensor; the optical system includes a condenser, a detection prism and an imaging lens, the condenser focuses the light from the light source onto the detection prism, and the light reflected from the interface between the detection prism and the cutting fluid to be tested is focused onto the image sensor through the imaging lens to form an image of the light and dark boundary.

[0011] Furthermore, the data acquisition module includes a temperature sensor, a driving circuit, an operational amplifier circuit, an A / D conversion circuit and an FPGA;

[0012] The temperature sensor is used to collect temperature information of the cutting fluid to be tested and transmit it to the FPGA;

[0013] The driving circuit is used to drive the optical imaging module and the temperature sensor to operate;

[0014] The operational amplifier circuit is used to amplify the output data of the image sensor and transmit the amplified data to the A / D conversion circuit;

[0015] The A / D conversion circuit is used to convert the data output by the operational amplifier circuit into a digital signal and transmit it to the FPGA;

[0016] The FPGA is used to control the operation of other components of the data acquisition module and to transmit the received data to the communication and processing module.

[0017] Furthermore, the driving timing of the FPGA controls the driving circuit to achieve synchronous operation of the optical imaging module and the temperature sensor.

[0018] Furthermore, the communication and processing module includes a host computer, which calculates the concentration of the cutting fluid to be tested based on the data output by the data acquisition module.

[0019] Furthermore, the concentration of the cutting fluid to be tested is calculated based on the data output by the data acquisition module, and the specific process includes:

[0020] Perform base conversion on the data output by the data acquisition module;

[0021] The data was then smoothed to remove noise;

[0022] Determine the pixel position of the light-dark dividing line in the image based on the processed data;

[0023] The concentration of the cutting fluid to be tested is obtained according to a pre-established mathematical model between the pixel position of the dividing line and the solution concentration.

[0024] Furthermore, the pixel position of the light-dark boundary line in the image is determined by using an inflection point extraction algorithm.

[0025] In another aspect, a cutting fluid concentration measuring device is provided, comprising a housing, a circuit board containing an FPGA main control chip and an A / D conversion chip, a rubber gasket, a measuring module, and a waterproof cable disposed in the housing; the measuring module is used to detect imaging information and temperature information of the cutting fluid to be measured;

[0026] The shell is a hollow cavity structure, including a lower cover and an upper cover installed above the lower cover. A rubber gasket is arranged between the upper cover and the lower cover, and the three form a sealing structure; the measuring module is arranged in the groove of the lower cover, and the circuit board is installed in the upper cover; a window is opened on the lower cover to connect the cutting fluid to be tested and the measuring module, and the window allows the cutting fluid to be tested to contact the measuring module to form an interface; the entire device is connected to the host computer through the waterproof cable.

[0027] Furthermore, the measurement module includes a prism seat, a detection prism, a temperature sensor seat, a temperature sensor, a condenser seat, a condenser, an aperture, a light source, a light source seat, a light source spacer, a photoelectric detection device, a detection module seat, an imaging lens and an imaging lens seat;

[0028] The detection module seat is assembled in the groove of the lower cover, and the prism seat is installed at one end of the detection module seat, which end is located on the same side as the window; the prism seat is provided with a first groove, which passes through the prism seat, and the detection prism is installed in the first groove and can contact the cutting fluid to be tested; the prism seat is provided with a first through hole, and the side of the detection module seat is provided with a second groove, the temperature sensor seat is installed in the first through hole and the second groove, and the temperature sensor is installed on the temperature sensor seat and contacts the cutting fluid to be tested through the first through hole; the other end of the detection module seat is provided with a second through hole and a third through hole that pass through the detection module seat, the light source seat is installed in the second through hole and is fixed to the detection module seat, and the light source is fixedly installed through the light source partition column On the light source seat; the condenser seat is installed in the second through hole and is coaxial with the light source, and is close to one end of the detection module seat; along the direction of the output light of the light source, the aperture and the condenser are installed on the condenser seat in sequence; the photoelectric detection device is installed in the third through hole and is located at the other end of the detection module seat; the imaging lens seat is installed in the third through hole and is coaxial with the photoelectric detection device, and is close to one end of the detection module seat, and the imaging lens is installed on the imaging lens seat; the relative position relationship between the light path in the second through hole and the detection prism is: the output light of the light source is focused on the detection surface of the detection prism, and the relative position relationship between the light path in the third through hole and the detection prism is: the imaging lens can completely receive the light reflected by the detection prism to achieve complete imaging;

[0029] All components are assembled with silicone rubber seals.

[0030] Compared with the prior art, the present invention has the following significant advantages:

[0031] (1) The device of the present invention uses the optical critical angle method as the measurement principle. The measurement device of the optical critical angle method is usually simple and easy to realize automation and online monitoring.

[0032] (2) The device of the present invention adopts a prism with a trapezoidal design. This structure extends the effective light propagation path, thereby playing a key role in improving measurement accuracy. In addition, compared with other prisms with the same optical path length, the trapezoidal prism occupies less space, which helps to make the design of the entire measuring device more miniaturized. The structure of the trapezoidal prism also ensures its excellent stability and mechanical properties, which is conducive to maintaining the long-term stability of the optical components.

[0033] (3) A light-emitting diode (LED) with a wavelength of 532 nanometers was selected as the illumination source. This type of LED is highly efficient and energy-saving, with a longer service life, thus reducing long-term expenses. It also generates less heat, which helps maintain the stability of heat-sensitive samples. In addition, LED illumination has great adjustability in terms of volume and shape, and its small size allows it to be easily integrated into precision optical devices.

[0034] (4) The present invention uses linear array CMOS as the photoelectric detection device. Linear array CMOS is more economical to manufacture, has lower power consumption, and has a sampling speed that exceeds CCD. Its noise, resolution, and sensitivity are also gradually improving with technological progress.

[0035] (5) The present invention uses DS18B20 as a temperature detection component, which is known for its accurate temperature measurement function; it supports a one-line interface, which greatly saves the system's input / output resources and simplifies wiring requirements; in addition, its stainless steel housing provides high durability and improves anti-interference capabilities in harsh environments, ensuring that the equipment can operate reliably even under severe conditions.

[0036] (5) The present invention uses Raspberry Pi 4B as the host computer, which has the advantages of low power consumption, high performance, low price and scalability.

[0037] (6) The device of the present invention has the advantages of simplicity, small size, low cost, simple optical path, etc., and is suitable for industrial production.

[0038] The present invention is further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a design diagram of a cutting fluid concentration measurement system according to an embodiment of the present invention.

[0040] Figure 2 1 is a structural diagram of a cutting fluid concentration measuring device in one embodiment.

[0041] Figure 3 1 is a structural diagram of a measuring module in a cutting fluid concentration measuring device in one embodiment. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0043] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0044] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] In one embodiment, combined Figure 1 , provides a cutting fluid concentration measurement system, the system comprising an optical imaging module, a data acquisition module, and a communication and processing module;

[0046] The optical imaging module is used to perform optical imaging on the cutting fluid to be tested and transmit the imaging information to the data acquisition module;

[0047] The data acquisition module is used to collect the imaging data transmitted by the optical imaging module and the temperature information of the cutting fluid to be measured, and transmit them to the communication and processing module;

[0048] The communication and processing module is used to calculate the concentration value of the cutting fluid to be tested based on the received information.

[0049] Optionally, in one embodiment, the measurement system further comprises:

[0050] The display module is used to automatically store, identify and display the refractive index and solution concentration data of the cutting fluid to be tested on the host computer; it is also used to generate charts and data with one click for easy reference.

[0051] Furthermore, in one embodiment, the optical imaging module forms an image of a light-dark boundary based on the critical angle method principle, and the position of the image boundary line is related to the concentration of the cutting fluid.

[0052] The critical angle method works as follows: if the incident light's angle of incidence is below the critical angle for total internal reflection, the light will be both reflected and refracted, resulting in a partial loss of energy in the reflected light, creating a dark area. However, when the incident light's angle of incidence exceeds or equals the critical angle for total internal reflection, the light will be completely reflected without energy loss, resulting in a brighter area.

[0053] Furthermore, in one embodiment, the optical imaging module includes a light source, an optical system and an image sensor; the optical system includes a condenser, a detection prism and an imaging lens, the condenser focuses the light from the light source onto the detection prism, and the light reflected from the interface between the detection prism and the cutting fluid to be tested is focused onto the image sensor through the imaging lens to form an image of the light and dark boundary.

[0054] Furthermore, in one embodiment, the data acquisition module includes a temperature sensor, a driving circuit, an operational amplifier circuit, an A / D conversion circuit, and an FPGA as a control core;

[0055] The temperature sensor is used to collect temperature information of the cutting fluid to be tested and transmit it to the FPGA;

[0056] The driving circuit is used to drive the optical imaging module and the temperature sensor to operate;

[0057] The operational amplifier circuit is used to amplify the output data of the image sensor and transmit the amplified data to the A / D conversion circuit;

[0058] The A / D conversion circuit is used to convert the data output by the operational amplifier circuit into a digital signal and transmit it to the FPGA;

[0059] The FPGA is used to control the operation of other components of the data acquisition module and to transmit the received data to the communication and processing module.

[0060] Here preferably, the FPGA transmits data to the communication and processing module via RS232 protocol.

[0061] Here, preferably, the driving timing of the FPGA controls the driving circuit to achieve synchronous operation of the optical imaging module and the temperature sensor, thereby achieving synchronous data collection.

[0062] Furthermore, in one embodiment, the communication and processing module includes a host computer, which calculates the concentration of the cutting fluid to be tested based on the data output by the data acquisition module (first calculates the refractive index, and then calculates the concentration based on the refractive index).

[0063] Here, the host computer includes but is not limited to a computer, Raspberry Pi 4B, etc.

[0064] Furthermore, in one embodiment, the concentration of the cutting fluid to be tested is calculated based on the data output by the data acquisition module, and the specific process includes:

[0065] Perform base conversion on the data output by the data acquisition module;

[0066] The data was then smoothed to remove noise;

[0067] Determine the pixel position of the light-dark dividing line in the image based on the processed data;

[0068] The concentration of the cutting fluid to be tested is obtained according to a pre-established mathematical model between the pixel position of the dividing line and the solution concentration;

[0069] The concentration of the cutting fluid to be measured is compensated according to the temperature information.

[0070] Here, in some embodiments, the smoothing process uses, but is not limited to, Savitzky-Golay filtering. The idea behind this filtering method is to fit an n-order polynomial in a window of a given length of (2m+1), and use the fitted polynomial to obtain the desired window center point value. Different values ​​of m and n can be set to meet different filtering requirements: a larger m value results in a longer sliding window and a better smoothing effect for small-scale fluctuations, but an excessively large m value can also result in loss of spot details; a larger n value results in more coefficients in the fitting polynomial, and the resulting filtered and smoothed curve is closer to the original curve.

[0071] Here, in some embodiments, the pixel position of the light-dark dividing line in the image is determined by, but not limited to, an inflection point extraction algorithm, the idea of ​​which is an algorithm for detecting inflection points in a curve in a line data stream. The inflection point is detected by calculating the difference between consecutive data points. First, the vertical distance between each point and the straight line y=x is calculated. The point with the largest vertical distance is considered to be a candidate inflection point. In order to determine whether a point is a true inflection point, the angle between the point and the previous and next points is calculated. If this angle is less than 90 degrees, it is considered that an inflection point has been found. The algorithm uses a sliding window to calculate the difference value. When the difference value changes from horizontal to a sharp drop, it is considered that an inflection point has been found.

[0072] Here, in some embodiments, the mathematical model between the pixel position of the dividing line and the solution concentration is obtained through pre-experimental calibration and can be a linear or other appropriate mathematical model.

[0073] In one embodiment, combined Figure 2, provides a cutting fluid concentration measuring device, the device comprising a housing, and a circuit board b containing an FPGA main control chip and an A / D conversion chip, a rubber gasket c, a measuring module d, and a waterproof cable f disposed in the housing; the measuring module d is used to detect imaging information and temperature information of the cutting fluid to be measured;

[0074] The shell has a hollow cavity structure, including a lower cover e and an upper cover a installed above the lower cover e. A rubber gasket c is arranged between the upper cover a and the lower cover e, and the three form a sealed structure; the measurement module d is arranged in the groove of the lower cover e, and the circuit board b is installed in the upper cover a; a window is opened on the lower cover e to connect the cutting fluid to be tested and the measurement module d, and the window allows the cutting fluid to be tested to contact the measurement module d to form an interface; the entire device is connected to the host computer via the waterproof cable f.

[0075] Furthermore, in one embodiment, in combination Figure 3 The measuring module includes a prism seat 1, a detection prism 2, a temperature sensor seat 3, a temperature sensor 4, an LED condenser seat 5, an LED condenser 6, an LED aperture 7, an LED light source 8, an LED light source seat 9, an LED light source spacer 10, a photoelectric detection device 11, a detection module seat 12, an imaging lens 14 and an imaging lens seat 15;

[0076] The detection module seat 12 is assembled in the groove of the lower cover, and the prism seat 1 is installed at one end of the detection module seat 12, which end is located on the same side as the window; the prism seat 1 is provided with a first groove, which first groove passes through the prism seat 1, and the detection prism 2 is installed in the first groove and can contact the cutting fluid to be measured; the prism seat 1 is provided with a first through hole, and the side of the detection module seat 12 is provided with a second groove, the temperature sensor seat 3 is installed in the first through hole and the second groove, and the temperature sensor 4 is installed on the temperature sensor seat 3 and contacts the cutting fluid to be measured through the first through hole; the other end of the detection module seat 12 is provided with a second through hole and a third through hole that passes through the detection module seat 12, the LED light source seat 9 is installed in the second through hole and fixed to the detection module seat 12, and the LED light source 8 is fixedly mounted on the LED light source seat 9 through the LED light source partition column 10 (LED partition column protection Prevent LED position deviation); the LED condenser seat 5 is installed in the second through hole and is coaxial with the LED light source 8, and is close to one end of the detection module seat 12; along the output light direction of the LED light source 8, the LED aperture 7 and the LED condenser 6 are sequentially installed on the LED condenser seat 5; the photoelectric detection device 11 is installed in the third through hole and is located at the other end of the detection module seat 12; the imaging lens seat 15 is installed in the third through hole and is coaxial with the photoelectric detection device 11, and is close to one end of the detection module seat 12, and the imaging lens 14 is installed on the imaging lens seat 15; the relative position relationship between the light path in the second through hole and the detection prism 2 is: the output light of the LED light source 8 is focused on the detection surface of the detection prism 2, and the relative position relationship between the light path in the third through hole and the detection prism 2 is: the imaging lens 14 can completely receive the light reflected by the detection prism 2 to achieve complete imaging;

[0077] All components are assembled with silicone rubber seals to provide a waterproof seal.

[0078] Here, the fixing method between the components adopts but is not limited to screws, blind hole screws, etc.

[0079] Preferably, in some embodiments, the detection prism 2 is a trapezoidal prism. This structure extends the effective light propagation path, thereby playing a key role in improving measurement accuracy. In addition, compared with other prisms with the same optical path length, the trapezoidal prism takes up less space, which helps to make the design of the entire measuring device more miniaturized. The structure of the trapezoidal prism also ensures its excellent stability and mechanical properties, which is conducive to maintaining the long-term stability of the optical component. Further herein, in some embodiments, the prism is made of H-K9L material. Further herein, in some embodiments, the two inclined surfaces of the trapezoidal prism are blackened to reduce the influence of stray light.

[0080] In some embodiments, the temperature sensor 4 uses but is not limited to the DS18B20 temperature sensor, which is known for its precise temperature measurement function; it supports a one-line interface, which greatly saves the system's input / output resources and simplifies wiring requirements; in addition, its stainless steel casing provides high durability and improves anti-interference capabilities in harsh environments, ensuring that the device can operate reliably even under harsh conditions.

[0081] In some embodiments, the LED light source 8 is a monochromatic LED with a wavelength range of 532 nm.

[0082] In some embodiments, the photoelectric detection device uses, but is not limited to, a linear array CMOS. The linear array CMOS is more economical to manufacture, consumes less power, and has a sampling speed exceeding that of a CCD.

[0083] Based on the above system and device, the process of measuring the concentration of a solution includes the following steps:

[0084] 1. Completely immerse the cutting fluid concentration measuring device into the cutting fluid to be tested;

[0085] 2. The LED condenser 6 focuses the light from the LED light source 8 onto the trapezoidal prism 2. The light that meets the total internal reflection condition will be reflected by the prism. The reflected light is then focused by the imaging lens 14 onto the linear array CMOS sensor 11, forming an image with light and dark boundaries.

[0086] 3. The linear array CMOS sensor collects images and transmits them together with the temperature information collected by the temperature sensor to the data communication and processing module, which transmits the data to the host computer through the RS232 protocol;

[0087] 4. The software running in the host computer processes the image, identifies the pixel position of the dividing line, calculates the refractive index of the cutting fluid to be tested, and further determines the concentration value of the cutting fluid to be tested.

[0088] In summary, the present invention provides an innovative cutting fluid concentration measurement system and device, which has the characteristics of high degree of automation, simple operation, and high measurement accuracy. It is suitable for industrial automation production environments and provides effective technical support for the metal processing industry.

[0089] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only illustrative of the principles of the present invention. Without departing from the spirit and scope of the present invention, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A cutting fluid concentration measurement system, characterized in that: The system includes an optical imaging module, a data acquisition module, and a communication and processing module; The optical imaging module is used to perform optical imaging on the cutting fluid to be tested and transmit the imaging information to the data acquisition module; The data acquisition module is used to collect the imaging data transmitted by the optical imaging module and the temperature information of the cutting fluid to be measured, and transmit them to the communication and processing module; The communication and processing module is used to calculate the concentration value of the cutting fluid to be tested based on the received information.

2. The cutting fluid concentration measurement system according to claim 1, characterized in that: The optical imaging module forms an image of the light-dark boundary based on the critical angle method principle, and the position of the image boundary line is related to the concentration of the cutting fluid.

3. The cutting fluid concentration measurement system according to claim 2, characterized in that: The optical imaging module includes a light source, an optical system and an image sensor; the optical system includes a condenser, a detection prism and an imaging lens. The condenser focuses the light from the light source onto the detection prism, and the light reflected from the interface between the detection prism and the cutting fluid to be tested is focused onto the image sensor through the imaging lens to form an image of the light and dark boundary.

4. The cutting fluid concentration measurement system according to claim 1, characterized in that: The data acquisition module includes a temperature sensor, a driving circuit, an operational amplifier circuit, an A / D conversion circuit and an FPGA; The temperature sensor is used to collect temperature information of the cutting fluid to be tested and transmit it to the FPGA; The driving circuit is used to drive the optical imaging module and the temperature sensor to operate; The operational amplifier circuit is used to amplify the output data of the image sensor and transmit the amplified data to the A / D conversion circuit; The A / D conversion circuit is used to convert the data output by the operational amplifier circuit into a digital signal and transmit it to the FPGA; The FPGA is used to control the operation of other components of the data acquisition module and to transmit the received data to the communication and processing module.

5. The cutting fluid concentration measurement system according to claim 4, characterized in that: The driving timing of the FPGA controls the driving circuit to achieve synchronous operation of the optical imaging module and the temperature sensor.

6. The cutting fluid concentration measurement system according to claim 1, characterized in that: The communication and processing module includes a host computer, which calculates the concentration of the cutting fluid to be tested according to the data output by the data acquisition module.

7. The cutting fluid concentration measurement system according to claim 3 or 6, characterized in that: The concentration of the cutting fluid to be tested is calculated based on the data output by the data acquisition module. The specific process includes: Perform base conversion on the data output by the data acquisition module; The data was then smoothed to remove noise; Determine the pixel position of the light-dark dividing line in the image based on the processed data; The concentration of the cutting fluid to be tested is obtained according to a pre-established mathematical model between the pixel position of the dividing line and the solution concentration.

8. The cutting fluid concentration measurement system according to claim 7, characterized in that: The pixel position of the light-dark boundary line in the image is determined by using an inflection point extraction algorithm.

9. A cutting fluid concentration measuring device based on the system according to any one of claims 1 to 8, characterized in that: The device includes a housing, and a circuit board containing an FPGA main control chip and an A / D conversion chip, a rubber gasket, a measurement module, and a waterproof cable arranged in the housing; the measurement module is used to detect imaging information and temperature information of the cutting fluid to be tested; The shell is a hollow cavity structure, including a lower cover and an upper cover installed above the lower cover. A rubber gasket is arranged between the upper cover and the lower cover, and the three form a sealing structure; the measuring module is arranged in the groove of the lower cover, and the circuit board is installed in the upper cover; a window is opened on the lower cover to connect the cutting fluid to be tested and the measuring module, and the window allows the cutting fluid to be tested to contact the measuring module to form an interface; the entire device is connected to the host computer through the waterproof cable.

10. The cutting fluid concentration measuring device according to claim 9, characterized in that: The measuring module includes a prism seat, a detection prism, a temperature sensor seat, a temperature sensor, a condenser seat, a condenser, an aperture, a light source, a light source seat, a light source spacer, a photoelectric detection device, a detection module seat, an imaging lens and an imaging lens seat; The detection module seat is assembled in the groove of the lower cover, and the prism seat is installed at one end of the detection module seat, which end is located on the same side as the window; the prism seat is provided with a first groove, which passes through the prism seat, and the detection prism is installed in the first groove and can contact the cutting fluid to be tested; the prism seat is provided with a first through hole, and the side of the detection module seat is provided with a second groove, the temperature sensor seat is installed in the first through hole and the second groove, and the temperature sensor is installed on the temperature sensor seat and contacts the cutting fluid to be tested through the first through hole; the other end of the detection module seat is provided with a second through hole and a third through hole that pass through the detection module seat, the light source seat is installed in the second through hole and is fixed to the detection module seat, and the light source is fixedly installed through the light source partition column On the light source seat; the condenser seat is installed in the second through hole and is coaxial with the light source, and is close to one end of the detection module seat; along the direction of the output light of the light source, the aperture and the condenser are installed on the condenser seat in sequence; the photoelectric detection device is installed in the third through hole and is located at the other end of the detection module seat; the imaging lens seat is installed in the third through hole and is coaxial with the photoelectric detection device, and is close to one end of the detection module seat, and the imaging lens is installed on the imaging lens seat; the relative position relationship between the light path in the second through hole and the detection prism is: the output light of the light source is focused on the detection surface of the detection prism, and the relative position relationship between the light path in the third through hole and the detection prism is: the imaging lens can completely receive the light reflected by the detection prism to achieve complete imaging; All components are assembled with silicone rubber seals.

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