Infrared detection system and method for weakening impact performance of a water jet cutting nozzle

Abstract

The application discloses an infrared detection system and method for weakening impact performance of a hydraulic cutting nozzle, and the system comprises a high-pressure water generating device, a jet impact device, a heating device and a data acquisition device; the jet impact device comprises a jet device, a hydraulic cutting nozzle and an impact bearing plate; and the data acquisition device comprises an infrared camera and a data acquisition computer. The infrared detection system and method for weakening impact performance of the hydraulic cutting nozzle are comparative test tests carried out under the conditions of a set jet impact target distance and jet pressure on the premise of considering the influence of the nozzle external flow field on nozzle wear and impact performance weakening, the weakening situation of the impact performance of the hydraulic cutting nozzle is calculated by measuring the temperature changes of the impact bearing plates corresponding to the to-be-tested nozzle and a standard nozzle, the hydraulic cutting nozzle can be rapidly detected in the regular maintenance process of hydraulic mining, and quantifiable wear data support can be provided for replacement of the hydraulic cutting nozzle.

Description

TECHNICAL FIELD

[0001] The present application relates to a nozzle impact performance detection system and method, in particular to an infrared detection system and method for weakening the impact performance of a water jet cutting nozzle, and belongs to the technical field of hydraulic mining. BACKGROUND

[0002] Hydraulic mining refers to the use of water power to complete all or part of the mining, transportation, lifting and other production links of mine production. Hydraulic mining can greatly reduce the configuration of underground roadways and underground workers, reduce the cost of coal mining, and improve the safety of coal mining. Hydraulic mining is usually applied in unstable seams, steeply inclined seams, remined seams and irregularly occurring areas or blocks. As long as the seam conditions are suitable, it can fully exert its advantages.

[0003] The mining process of hydraulic mining is to use high-pressure water jet to cut and break the ore body. Hydraulic cutting can be divided into pure water, additive and abrasive hydraulic cutting. The hydraulic cutting of hydraulic mining is abrasive hydraulic cutting, which mixes water and solid abrasive particles, and the solid particles obtain strong kinetic energy in the high-pressure water jet to impact the ore body. Due to the addition of abrasive particles, the hydraulic cutting nozzle as the core component will inevitably be worn after a long period of hydraulic mining operation, which will gradually reduce its impact performance. Once the impact performance of the hydraulic cutting nozzle is seriously weakened or even cannot effectively impact and break the coal body, the continuity of hydraulic mining cannot be guaranteed, which will affect the mining efficiency of hydraulic mining. Therefore, the hydraulic cutting nozzle usually needs to be checked regularly, and the hydraulic cutting nozzle with excessive wear is replaced to ensure the mining efficiency of hydraulic mining.

[0004] Because the hydraulic cutting nozzle usually adopts a smaller inner diameter to achieve a larger jet pressure, the wear of the inner diameter of the hydraulic cutting nozzle cannot be directly measured by a measuring tool, especially for the inner diameter with a conical inner surface. Currently, the experience evaluation method and the plug pin measurement method are usually used for regular inspection of the hydraulic cutting nozzle. The experience evaluation method relies on the naked eye observation of the operator and comparison with the reference sample for evaluation. This evaluation method has no quantifiable index, and the judgment result is greatly affected by human subjective factors, and the accuracy and reliability of the judgment are poor. The plug pin measurement method is to insert the standard plug pin or plug pin into the inner diameter of the hydraulic cutting nozzle, and to evaluate whether the standard plug pin or plug pin can pass. Since the wear of the inner diameter is usually not regular and uniform, when the longitudinal section of the worn inner diameter is not a standard circle, there is often a situation that although the standard plug pin or plug pin cannot pass, the actual wear has exceeded the standard.

[0005] The Chinese invention patent with the application number 201910820360.9 "A method for detecting and evaluating the wear degree of the inner hole of a cold coating nozzle" provides a solution for the unmeasurable inner hole size of the nozzle by measuring the gas flow rate of the nozzle to be measured and the standard hole diameter gas flow rate, but it is aimed at the cold spraying nozzle that uses compressed gas as the accelerating medium to drive metal particles, not the hydraulic cutting nozzle that uses high-pressure water jet. It does not consider the impact of the external flow field of the nozzle on the wear and impact performance weakening of the nozzle. In the process of hydraulic mining, the hydraulic mining radius can reach more than 10m, and the high-pressure water jet sprayed from the hydraulic cutting nozzle is easily affected by air resistance and entrainment under the action of the external air flow field, which can cause the jet quality to decrease, and the external flow field of the hydraulic cutting nozzle is also an important factor affecting the efficiency of hydraulic mining. Therefore, the above-mentioned solution for the unmeasurable inner hole size of the nozzle is not applicable to the evaluation of the wear of the inner diameter of the hydraulic cutting nozzle for hydraulic mining. How to quickly and accurately detect the wear and impact performance weakening of the hydraulic cutting nozzle and provide quantifiable wear data support for the regular inspection of the hydraulic cutting nozzle is a problem that needs to be solved to ensure the efficiency of hydraulic mining. SUMMARY

[0006] In view of the problems existing in the prior art, the present application provides an infrared detection system and method for the impact performance weakening of a hydraulic cutting nozzle, which can quickly detect the hydraulic cutting nozzle during regular maintenance of hydraulic mining and provide quantifiable wear data support for replacement of the hydraulic cutting nozzle.

[0007] To achieve the above-mentioned purpose, the infrared detection system for the impact performance weakening of the hydraulic cutting nozzle comprises a high-pressure water generating device, a jet impact device, a heating device, and a data acquisition device.

[0008] The high-pressure water generating device comprises a water tank and a high-pressure water pressurizing and control unit, and the output end of the water tank is connected in communication with the input end of the high-pressure water pressurizing and control unit through a water conveying pipeline.

[0009] The jet impact device comprises a jet, a hydraulic cutting nozzle, and an impact bearing plate, the input end of the jet is connected in communication with the output end of the high-pressure water pressurizing and control unit through a water conveying pipeline, the hydraulic cutting nozzle is installed on the output end of the jet, and the impact bearing plate with a thin plate structure is arranged in front of the hydraulic cutting nozzle, and the plate surface of the impact bearing plate is perpendicular to the jet direction of the hydraulic cutting nozzle.

[0010] The heating device comprises a heater for heating the impact bearing plate.

[0011] The data acquisition device comprises an infrared camera and a data acquisition computer, the infrared camera is arranged in front of the impact bearing plate corresponding to the water jet cutting nozzle, and the photographing direction of the infrared camera is perpendicular to the plate surface of the impact bearing plate.

[0012] As a preferred scheme of the present application, the impact bearing plate is an aluminum thin plate.

[0013] An infrared detection method for weakening the impact performance of a water jet cutting nozzle based on an infrared detection system for weakening the impact performance of the water jet cutting nozzle, and the specific detection steps are as follows:

[0014] Step 1, install a standard water jet cutting nozzle on the output end of the ejector, set the jet mass flow rate of the jet to m, start the heater to heat the impact bearing plate, and when the temperature of the impact bearing plate is heated to T set , start the high-pressure water pressurization and control unit to perform a jet impact test, the high-pressure water jet forms a temperature reduction area on the plate surface of the impact bearing plate, and at the same time, the temperature distribution data T t (x,y) of the surface of the impact bearing plate within the jet impact time t is captured by the infrared camera.

[0015] Step 2, construct a three-level standard function based on points, lines and surfaces according to the surface temperature distribution data T t (x,y), and the specific steps are as follows,

[0016] Step 2-1, analyze the temperature change of the impact center point, and construct a function relationship between the jet impact time t and the temperature change of the impact center point

[0017] A(t)=T set -T t (0,0)

[0018] In the formula, t is the jet impact time of the water jet cutting nozzle, A(t) is the temperature change function of the impact center point, and (0,0) is the center coordinate of the vertical jet impact area.

[0019] Step 2-2, calculate the equivalent radius of the temperature reduction area, and construct a function relationship between the jet impact time t and the diffusion speed of the equivalent radius of the temperature reduction area

[0020]

[0021]

[0022] In the formula, S(t) is the area change of the temperature reduction area, R eq (t) is the equivalent radius of the temperature reduction area, B(t) is the radius diffusion speed of the temperature reduction area, S'(t) and Req (t) and R(t) are functions S(t) and R eq (t) is the derivative of the function S(t) and R

[0023] Step 2-3, after obtaining the heat removal rate, the function relationship between the jet impact time t and the injected jet evaporation fraction is constructed

[0024] Q = ∫∫q s dxdy

[0025]

[0026] In the formula, Q is the heat removal rate, C(t) is the injected jet evaporation fraction, q s is the surface heat flux of the temperature reduction area, J is the latent heat of water, and m is the jet mass flow rate of the jet injection.

[0027] Step 3, normalize the constructed three-level standard functions within the jet impact time t as follows

[0028] A1(t) = {[T set -T t (0,0)]-[T set -T t (0,0)]min} / {[T set -T t (0,0)]max-[T set -T t (0,0)]min}

[0029]

[0030]

[0031] In the formula, A1(t), B1(t) and C1(t) are new functions after normalization processing based on A(t), B(t) and C(t) respectively;

[0032] Step 4, after disassembling the standard hydraulic cutting nozzle, the hydraulic cutting nozzle to be detected is installed on the output end of the ejector, and then the jet impact test is carried out to obtain the temperature distribution on the surface of the impact bearing plate within the jet impact time t Then, according to the methods of Step 2 and Step 3, the normalized function of the temperature change of the impact center point corresponding to the jet impact time t is calculated The normalized function of the temperature reduction area radius diffusion speed And the normalized function of the injected jet evaporation fraction The formula is as follows:

[0033]

[0034]

[0035]

[0036] wherein, and are functions based on the temperature of the impact center point on the surface of the bearing plate after the jet impact, the temperature of the temperature reduction area, and the surface heat flux function of the water jet cutting nozzle to be detected;

[0037] Step 5, in the time region [0, t], compared with the data of the standard water jet cutting nozzle and the water jet cutting nozzle to be detected, an interpolation function is constructed

[0038]

[0039] wherein, ΔA(t), ΔB(t) and ΔC(t) are respectively the interpolation functions of the temperature of the impact center point, the radius diffusion speed of the temperature reduction area, and the evaporation fraction of the injected jet in the jet impact time t;

[0040] Step 6, based on the interpolation function, the ratio of the area surrounded by the interpolation function and the standard water jet cutting nozzle impact performance function and the time t axis in the jet impact time t is calculated, and is recorded as the wear coefficient of the water jet cutting nozzle as follows

[0041]

[0042] wherein, K1, K2 and K3 are respectively the wear coefficients of the water jet cutting nozzle based on the temperature of the impact center point, the radius diffusion speed of the temperature reduction area, and the evaporation fraction of the injected jet; ΔA'(t), ΔB'(t) and ΔC'(t) are respectively the derivatives of the functions ΔA(t), ΔB(t) and ΔC(t) with respect to the time t; A1'(t), B1'(t) and C1'(t) are respectively the derivatives of the functions A1(t), B1(t) and C1(t) with respect to the time t;

[0043] The statistical average method is used for comprehensive evaluation, and the wear coefficient K is defined as follows

[0044]

[0045] According to the wear coefficient K, the wear of the water jet cutting nozzle is divided into three grades of slight wear W1, general wear W2 and severe wear W3, and the grade division is as follows

[0046]

[0047] As a further improved scheme of the present application, in Step 2, the surface temperature distribution data T tWhen the (x, y) is constructed based on the three-level standard function of points, lines and surfaces, only the data with x>0 and y>0 is analyzed.

[0048] Compared with the prior art, the infrared detection system and method for weakening impact performance of the hydraulic cutting nozzle is a comparative test under the conditions of the set jet impact target distance and jet pressure, and the weakening impact performance of the hydraulic cutting nozzle is calculated by measuring the temperature change of the corresponding impact bearing plate of the measured nozzle and the standard nozzle, so that the hydraulic cutting nozzle can be quickly detected during the regular maintenance of the hydraulic mining, and the quantifiable wear data support can be provided for the replacement of the hydraulic cutting nozzle. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a structural schematic diagram of the infrared detection system for weakening impact performance of the hydraulic cutting nozzle.

[0050] Figure 2 is a curve diagram of the impact performance function of the measured nozzle and the impact performance function of the standard nozzle, wherein the solid line is the impact performance function curve of the standard nozzle, and the dotted line is the impact performance function curve of the measured nozzle.

[0051] In the figure: 1, water tank; 2, high-pressure water pressurization and control unit; 3, jet device; 4, temperature reduction area; 5, impact bearing plate; 6, heater; 7, infrared camera; 8, data acquisition computer. DETAILED DESCRIPTION

[0052] The present application will be further described below with reference to the accompanying drawings (the direction of the high-pressure water jet of the hydraulic cutting nozzle is described as the front direction).

[0053] As shown in Figure 1 , the infrared detection system for weakening impact performance of the hydraulic cutting nozzle comprises a high-pressure water generating device, a jet impact device, a heating device and a data acquisition device.

[0054] The high-pressure water generating device comprises a water tank 1 and a high-pressure water pressurization and control unit 2, and the output end of the water tank 1 is connected in communication with the input end of the high-pressure water pressurization and control unit 2 through a water conveying pipeline.

[0055] The jet impact device comprises a jet 3, a water cutting nozzle and an impact bearing plate 5, the input end of the jet 3 is connected with the output end of the high-pressure water pressurizing and control unit 2 through a water conveying pipeline, the water cutting nozzle is installed on the output end of the jet 3, the impact bearing plate 5 in a thin vertical plate structure is arranged in front of the water cutting nozzle, and the plate surface of the impact bearing plate 5 is arranged perpendicularly to the jetting direction of the water cutting nozzle, and the impact bearing plate 5 preferably adopts an aluminum thin vertical plate with small thickness and strong homogeneity, so as to ensure that the surface temperatures of the front vertical plate surface and the rear vertical plate surface have a consistent change rule.

[0056] The heating device comprises a heater 6 for heating the impact bearing plate 5.

[0057] The data acquisition device comprises an infrared camera 7 and a data acquisition computer 8, the infrared camera 7 is arranged in front of the impact bearing plate 5 corresponding to the water cutting nozzle, and the camera direction of the infrared camera 7 is arranged perpendicularly to the plate surface of the impact bearing plate 5, and the data acquisition computer 8 is electrically connected with the heater 6 and the infrared camera 7 respectively.

[0058] The infrared detection method for the impact performance of the water cutting nozzle is a comparative test under the conditions of a set jet impact target distance and jet pressure, and the weakening condition of the impact performance of the water cutting nozzle is calculated through an indirect measurement method. Figure 1 As shown in the jet impact detection, the initial temperature of the plate surface of the impact bearing plate 5 is kept consistent during the test process, the high-pressure water jet sprayed by the water cutting nozzle is diverged under the influence of air resistance and entrainment during the process of impacting the impact bearing plate 5, and then the jet impact track radius formed after the high-pressure water jet vertically impacts the rear vertical surface of the impact bearing plate 5 is increased, since the temperature of the jet water is lower than the initial temperature of the surface of the impact bearing plate 5, heat exchange is caused in the vertical impact area, so that a temperature reduction area 4 is formed on the plate surface of the impact bearing plate 5, the area of the temperature reduction area 4 is increased with the increase of the jet impact time, and the initial area is greater than the longitudinal cross-sectional area of the inner diameter of the water cutting nozzle, since the impact bearing plate 5 has small thickness and strong homogeneity, the surface temperatures of the front vertical plate surface and the rear vertical plate surface have a consistent change rule, so that the dynamic change of the temperature can be obtained in real time through the infrared camera 7 from the front vertical plate surface side.

[0059] Before the test, first define the impact point of the axis of the inner diameter of the water jet cutting nozzle projected on the surface of the impact bearing plate 5 as the origin, and the x-axis and y-axis as the width and height directions of the impact bearing plate 5; keep the water temperature and room temperature the same in the jet impact system, when the impact performance of the water jet cutting nozzle changes in a small range, the changes of the external flow field and the temperature field of the impact area of the water jet cutting nozzle are approximately monotonous, when the water jet cutting nozzle is worn, the efficiency of the high-pressure water jet impact breaking solid will be greatly reduced, the main reason is that the convergence of the nozzle is poor, which leads to the strengthening of air entrainment and the serious divergence of the high-pressure water jet, so the effective mass of the high-pressure water jet impacting the surface of the impact bearing plate 5 will be significantly reduced, and therefore the degree of temperature change will be reduced. Thus, the weakening of the impact performance of the water jet cutting nozzle can be calculated by measuring the temperature change of the impact bearing plate 5 corresponding to the test nozzle and the standard nozzle, and the specific detection steps are as follows:

[0060] Step 1, install the standard water jet cutting nozzle on the output end of the jet, set the jet mass flow rate of the jet to m, start the heater 6 to heat the impact bearing plate 5, and when the temperature of the impact bearing plate 5 is heated to T set , start the high-pressure water pressure and control unit 2 to perform jet impact test, and capture the temperature distribution data T t (x,y) of the surface of the impact bearing plate 5 within the jet impact time t by the infrared camera 7.

[0061] Step 2, according to the measured surface temperature T t (x,y), construct a three-level standard function based on points, lines and surfaces, considering the symmetry of the temperature data, in order to reduce the workload, only the data with x>0 and y>0 are analyzed, as follows,

[0062] Step 2-1, analyze the temperature change of the impact center point, and construct the relationship between the jet impact time t and the temperature change of the impact center point, as follows:

[0063] A(t)=T set -T t (0,0)

[0064] In the formula, t is the jet impact time of the water jet cutting nozzle, A(t) is the temperature change of the impact center point, and (0,0) is the center coordinate of the vertical impact area of the jet;

[0065] Step 2-2, collect the changes of the temperature reduction area 4, and calculate the equivalent radius of the temperature reduction area 4, then construct the relationship between the jet impact time t and the radius diffusion speed of the temperature reduction area 4, as follows:

[0066]

[0067]

[0068] where S(t) is the area change of the temperature reduction region, R eq (t) is the equivalent radius of the temperature reduction region 4, B(t) is the radius diffusion speed of the temperature reduction region 4, S'(t) and R eq '(t) are the derivatives of the functions S(t) and R eq (t) with respect to time t, respectively.

[0069] Step 2-3, after obtaining the heat removal rate, the relationship between the jet impact time t and the injected jet evaporation fraction is constructed, as follows:

[0070] Q = ∫∫q s dxdy

[0071]

[0072] where Q is the heat removal rate, C(t) is the injected jet evaporation fraction, q s is the surface heat flux of the temperature reduction region 4, J is the latent heat of water, and m is the jet mass flow rate of the jet injection.

[0073] Step 3, in order to make a comparison, the constructed three-level standard functions are normalized within the jet impact time t, as follows:

[0074] A1(t) = {[T set -T t (0,0)]-[T set -T t (0,0)]min} / {[T set -T t (0,0)]max-[T set -T t (0,0)]min}

[0075]

[0076]

[0077] where A1(t), B1(t) and C1(t) are new functions after normalization based on A(t), B(t) and C(t), respectively.

[0078] Step 4, after dismounting the standard hydraulic cutting nozzle, the hydraulic cutting nozzle to be detected is installed on the output end of the ejector 3, and then the jet impact test is performed according to Step 1 to obtain the temperature distribution on the surface of the impact bearing plate 5 within the jet impact time t Then, the normalized function of the temperature change of the impact center point corresponding to the jet impact time t is calculated according to the method of Step 2 and Step 3 The normalized function of the radius diffusion speed of the temperature reduction area 4 And the normalized function of the injected jet evaporation fraction As follows:

[0079]

[0080]

[0081]

[0082] In the formula, And The functions of the temperature of the impact center point on the surface of the impact bearing plate 5 after the jet impact, the temperature of the temperature reduction area 4, and the surface heat flux of the water jet cutting nozzle to be detected are respectively based on the standard water jet cutting nozzle.

[0083] Step 5, in the time region [0, t], the data of the standard water jet cutting nozzle and the water jet cutting nozzle to be detected are compared, and an interpolation function is constructed, as follows:

[0084]

[0085] In the formula, ΔA(t), ΔB(t), and ΔC(t) respectively represent the interpolation functions of the temperature of the impact center point, the radius diffusion speed of the temperature reduction area, and the injected jet evaporation fraction within the jet impact time t.

[0086] Step 6: as shown in Figure 2 The ratio of the area surrounded by the interpolation function and the standard water jet cutting nozzle impact performance function axis within the jet impact time t is calculated based on the interpolation function, and is recorded as the wear coefficient of the water jet cutting nozzle under different indicators, as follows:

[0087]

[0088] In the formula, K1, K2, and K3 are respectively the wear coefficients of the water jet cutting nozzle based on the temperature of the impact center point, the radius diffusion speed of the temperature reduction area, and the injected jet evaporation fraction as the evaluation standard; ΔA'(t), ΔB'(t), and ΔC'(t) are respectively the derivatives of the functions ΔA(t), ΔB(t), and ΔC(t) with respect to time t; A1'(t), B1'(t), and C1'(t) are respectively the derivatives of the functions A1(t), B1(t), and C1(t) with respect to time t;

[0089] Secondly, the statistical average method is used for comprehensive evaluation, and the wear coefficient K is defined, as follows:

[0090]

[0091] According to the wear coefficient K, the wear of the water jet cutting nozzle is divided into three grades of slight wear W1, general wear W2 and serious wear W3, and the grade division is as follows:

[0092]

[0093] The wear condition of the water jet cutting nozzle can be indirectly reflected according to the measured specific value.

Claims

1. An infrared detection method for weakening the impact performance of a water jet cutting nozzle, wherein the infrared detection system for weakening the impact performance of the water jet cutting nozzle comprises a high-pressure water generating device, a jet impact device, a heating device, and a data acquisition device. The high-pressure water generating device comprises a water tank (1) and a high-pressure water pressurizing and control unit (2), and the output end of the water tank (1) is connected in communication with the input end of the high-pressure water pressurizing and control unit (2) through a water conveying pipeline. The jet impact device comprises a jet device (3), a water jet cutting nozzle, and an impact bearing plate (5), the input end of the jet device (3) is connected in communication with the output end of the high-pressure water pressurizing and control unit (2) through a water conveying pipeline, the water jet cutting nozzle is installed on the output end of the jet device (3), and the impact bearing plate (5) in a thin plate structure is arranged in front of the water jet cutting nozzle, and the plate surface of the impact bearing plate (5) is arranged perpendicularly to the jet direction of the water jet cutting nozzle. The heating device comprises a heater (6) for heating the impact bearing plate (5). The data acquisition device comprises an infrared camera (7) and a data acquisition computer (8), the infrared camera (7) is arranged in front of the impact bearing plate (5) corresponding to the water jet cutting nozzle, and the camera direction of the infrared camera (7) is arranged perpendicularly to the plate surface of the impact bearing plate (5), and the data acquisition computer (8) is electrically connected with the heater (6) and the infrared camera (7) respectively. characterized in that The specific detection steps are as follows: Step1, install the standard hydraulic cutting nozzle on the output end of the jet device (3), and set the jet mass flow rate of the jet to m, start the heater (6) to heat the impact bearing plate (5), and wait for the temperature of the impact bearing plate (5) to heat to T set When the temperature of the impact bearing plate (5) is heated to T, start the high-pressure water pressurization and control unit (2) to perform a jet impact test, and the high-pressure water jet forms a temperature reduction area (4) on the surface of the impact bearing plate (5), and at the same time, the infrared camera (7) captures the temperature distribution data of the surface of the impact bearing plate (5) within the jet impact time t ; Step 2, according to the surface temperature distribution data Construct a three-level standard function based on points, lines and surfaces, as follows, Step 2-1, analyze the temperature change of the impact center point, and construct a function relationship between the jet impact time t and the temperature change of the impact center point In the formula, t is the jet impact time of the water jet cutting nozzle, is the temperature change function of the impact center point, and (0, 0) is the center coordinate of the jet vertical impact area. Step 2-2, calculate the equivalent radius of the temperature reduction area (4), and construct a diffusion speed function relationship between the jet impact time t and the equivalent radius of the temperature reduction area (4) wherein is the area change of the temperature reduction region (4), is the equivalent radius of the temperature reduction region (4), is the radius diffusion speed of the temperature reduction region (4), and are functions and derivative with respect to time t; Step 2-3, after obtaining the heat removal rate, a function relationship between the jet impact time t and the injected jet evaporation fraction is constructed where Q is the heat removal rate, is the injected jet evaporation fraction, is the surface heat flux of the temperature reduction zone (4), J is the latent heat of water, and m is the jet mass flow rate of the jet injection. Step 3, the three-level standard functions constructed are normalized as follows within the jet impact time t wherein , and are new functions based on , and normalized. Step4, after removing the standard water cutting nozzle, the water cutting nozzle to be tested is installed on the output end of the jet device (3), and then jet impact test is carried out to obtain the temperature distribution on the surface of the impact bearing plate (5) within the jet impact time t ; then, according to the methods of Step2 and Step3, the normalized function of the temperature change of the impact center point corresponding to the jet impact time t is calculated , the normalized function of the radius diffusion speed of the temperature reduction area (4) , and the normalized function of the injection jet evaporation fraction , as follows: wherein, , and are functions based on the temperature of the impact center point on the surface of the bearing plate (5) after the jet impact, the temperature of the temperature reduction zone (4), and the surface heat flux, respectively, of the water jet cutting nozzle to be detected. Step 5, in the time region [0, t], the data of the standard water jet cutting nozzle and the water jet cutting nozzle to be detected are compared, and an interpolation function is constructed wherein , and respectively represent an interpolation function of the temperature of the impact center point, the radius diffusion speed of the temperature reduction region (4), and the injection jet evaporation fraction within the jet impact time t. Step 6, within the jet impact time t, the ratio of the areas surrounded by the interpolation function and the standard water jet cutting nozzle impact performance function with respect to the time t axis is calculated based on the interpolation function, and is denoted as the wear coefficient of the water jet cutting nozzle as follows In the formula, K1, K2 and K3 are hydraulic cutting nozzle wear coefficients evaluated by the temperature of the impact center point, the radius diffusion speed of the temperature reduction area (4) and the injection jet evaporation fraction, respectively; , and are the derivatives of the functions , and with respect to time t, respectively; , and are the derivatives of the functions , and with respect to time t, respectively; The wear coefficient K is defined as follows by using the statistical average method for comprehensive evaluation According to the wear coefficient K, the wear of the water jet cutting nozzle is divided into three grades of slight wear W1, general wear W2, and severe wear W3, and the grade division is as follows 。 2. The method of claim 1, wherein the method is performed by an infrared camera. Step 2: According to the surface temperature distribution data When constructing the three-level standard function based on points, lines and surfaces, only the data with x>0 and y>0 is analyzed.

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