CN111781105A - A method and device for detecting dynamic wetting and lubricating characteristics of spray-type micro-droplets - Google Patents

Abstract

The invention discloses a method and a device for detecting the dynamic wetting and lubricating properties of spray-type micro-droplets. The present invention is as follows: 1. Perform a spray lubricating cutting simulation test for each tested liquid respectively. 2. Based on the AHP, the evaluation process of the dynamic wetting characteristics of the tested liquid is divided into a scheme layer, a criterion layer and a target layer. Third, construct the judgment matrix A of the criterion layer to the target layer. Fourth, construct the judgment matrix B, C, D for the plan layer and the target layer. 5. Perform consistency detection on matrices A, B, C, and D respectively; 6. Correct each matrix that fails the consistency detection; 7. Calculate the weight vector ω of each scheme to the target. The pros and cons of the dynamic wetting characteristics of each tested liquid are obtained. The present invention establishes an analytic hierarchy model based on the adhesion area, maximum penetration depth and lubricating effect of the atomized droplets respectively, and provides an optimal wettability suitable for different tools and workpiece materials in the cutting process through the calculation of the weight vector. Cutting fluid selection method.

Description

A method and device for detecting dynamic wetting and lubricating characteristics of spray-type micro-droplets

technical field

The invention belongs to the technical field of droplet wetting and lubricating characteristics detection, and particularly relates to a method and device for detecting the dynamic wetting and lubricating characteristics of microdroplets on a knife-chip contact surface with spray type micro-lubrication.

Background technique

Penetrating lubricity is an important factor in improving cutting efficiency, because better penetrating lubricity allows the cutting fluid to penetrate closer to the tool tip and increase the length and strength of oil film lubrication. So as to achieve better cooling and lubrication effect. With the continuous development of the concept of "green production", Minimum Quantity Lubrication (MQL) is considered to be a green, environmentally friendly way of supplying cutting fluid. When using MQL technology, cutting fluid often enters the tool-chip interface in the form of micro droplets to cool and lubricate. In the process of metal cutting, there is strong friction and wear between the tool and the surface of the workpiece. In order to improve the service life of the tool and the processing quality of the workpiece, it is necessary to quickly enter the cutting area with cutting fluid with good wettability and lubricity to improve the machining process. Therefore, it is necessary to detect the dynamic wetting and lubricating characteristics of cutting fluid droplets to select a cutting fluid with better performance.

Currently, there are not many related detection methods and devices. For example, the invention patent with the patent number (CN109307642A) discloses a method and device for measuring the wettability of each component in fine-grained sedimentary rocks. This patent detects the wettability of related minerals by droplet properties and contact angles by dropping micro-nano droplets on the minerals. Although the detection of wettability in this patent is related to microdroplets, it mainly focuses on the wettability of minerals, so it is not applicable to the dynamic wetting characteristics of droplets in the relative motion state in this field. The invention patent with the patent number of (CN103604726A) discloses a high temperature, strong chemically active liquid metal lithium wettability measurement system. The patent consists of a vacuum chamber, a vacuum pumping and measuring system, a sample stage and a heating system. The research object of this patent is the wetting characteristics of high temperature liquid metal to the substrate, and the contact angle of the droplet is measured by the influence analysis method. It is also not applicable to the research on the wetting characteristics of cutting fluid droplets in the state of relative motion in this field.

SUMMARY OF THE INVENTION

Aiming at the problem that it is difficult to detect the wetting and adhesion characteristics of the cutting fluid used in the current cutting process due to the main movement and feed movement of the tool-workpiece, the invention provides a droplet wetting method that simulates the working condition of the tool-workpiece contact surface. Method and device for detecting wet adhesion properties. The invention is a tool block and a relative motion mechanism device of the workpiece block that simulates the tool-workpiece relative motion condition; it is a relative motion mechanism device in which the tool-workpiece contact surface loading is controllable, the loading amplitude and the relative motion friction force can be fed back in real time. The motion control device is a method for visual detection and comparative evaluation of trace contours based on the penetration characteristics of droplets on workpiece blocks and the adhesion marks of droplets on tool blocks.

A method for detecting the dynamic wetting and lubricating properties of spray-type micro-droplets of the present invention is specifically as follows:

Step 1: Perform a spray lubrication cutting simulation test on m kinds of tested liquids, respectively, to obtain the adhesion area, maximum penetration depth and frictional force after lubrication of the tested liquids.

The micro-lubrication test method for the liquid to be tested is as follows: contact the tool block with the workpiece block, apply a pre-tightening force, and rub the two against each other. Liquid is applied to the interface between the tool block and the workpiece block. The adhesion area is the area of the measured liquid that adheres to the tool block or the workpiece block after the relative friction movement; the maximum penetration depth is the maximum depth of the measured liquid infiltrating the contact surface between the tool block and the workpiece block after the relative friction movement. The magnitude of the frictional force after lubrication is the average frictional force during relative frictional motion.

Step 2. Based on the AHP, the evaluation process of the dynamic wetting characteristics of the tested liquid is divided into three levels: the bottom layer is the scheme layer, which is composed of m kinds of tested liquids; the middle layer is the criterion layer, which is composed of the measured liquids. Adhesion area, maximum penetration depth, and friction force after lubrication. The top layer is the target layer, that is, the best dynamic wetting characteristics of the tested liquid.

Step 3: Construct the judgment matrix A of the criterion layer to the target layer. The adhesion area, the maximum penetration depth and the friction force after lubrication are taken as three factors respectively;

The establishment of matrix A is shown in formula (1).

a_ij越大表示第i个因素相较于第j个因素越重要；In formula (1), a _ij represents the importance influence ratio between the ith factor and the jth factor, i=1, 2, 3, j=1, 2, 3,

The larger a _ij is, the more important the i-th factor is than the j-th factor;

Calculate the weight vector ω _a =[ω _a1 ,ω _a2 ,ω _a3 ] ^T of the matrix A and the largest eigenroot λ _a .

Step 4: Constructing judgment matrices B, C, and D for the scheme layer and the target layer. According to the size of the adhesion area of m kinds of tested liquids, the characteristic ratio of adhesion area between m kinds of tested liquids is determined, and the matrix B is established as shown in formula (2). According to the maximum penetration depth of m kinds of tested liquids, determine the maximum penetration depth characteristic ratio between m kinds of tested liquids, and establish matrix C as shown in formula (3). According to the magnitude of the friction force after lubrication when the m kinds of tested liquids are tested, the characteristic ratio of the lubrication effect between the m kinds of tested liquids is determined, and the matrix D is established as shown in formula (4).

Among them, b _xy represents the characteristic ratio of the adhesion area between the x-th tested liquid and the y-th tested liquid; c _xy represents the maximum penetration depth characteristic ratio of the x-th tested liquid to the y-th tested liquid; d _xy represents The characteristic ratio of the lubricating effect of the xth tested liquid to the yth tested liquid; x=1,2,…,m, y=1,2,…,m.

Calculate the weight vectors ω _b =[ω _b1 ,ω _b2 ,...,ω _bm ] ^T , ω _c =[ω _c1 ,ω _c2 ,...,ω _cm ] ^T ,ω _d = [ω _d1 , ω _d2 , . . . , ω _dm ] ^T and the largest eigenvalues λ _b , λ _c , λ _d .

Step 5: Perform consistency detection on the matrices A, B, C, and D respectively; if the matrices A, B, C, and D all pass the consistency check, go directly to step 7.

Step 6: Correct the matrix A, B, C or D that fails the consistency check to make it pass the consistency check.

Step 7: Calculate the weight vector ω of each scheme to the target, as shown in formula (7).

The weight eigenvalues ω ₁ , ω ₂ ,...,ω _m correspond to m types of tested liquids respectively; the larger the weight eigenvalues are, the better the dynamic wetting characteristics of the corresponding tested liquids are, thus the m types of tested liquids are obtained. The pros and cons of the dynamic wetting properties of liquids.

Preferably, in step 6, the matrix A, B, C or D that fails the consistency detection is defined as the corrected matrix Z. The process of correcting the corrected matrix Z is as follows:

6-1: Construct the consistency matrix W according to the weight vector ω _z =[ω _z1 ,ω _z2 ,...,ω _zn ] ^T of the corrected matrix Z as shown in formula (5);

6-2: Calculate the perturbation matrix P as shown in formula (6);

P=Z-W (6)

6-3: According to the order of the absolute value of the off-diagonal elements in the perturbation matrix P from large to small, sort the elements of each corresponding position in the corrected matrix Z; The element of 1; the condition of correction is: if the element to be corrected zi _ij ≠2 and p _ij >0, then reduce zi _ij by 1. If z _ij ≠ 9 and p _ij <0, then increase z _ij by 1; otherwise, z _ij remains unchanged. When an element zi _ij greater than 1 in the corrected matrix Z is corrected, the element z _ji at the diagonal position of the element in the corrected matrix Z is corrected synchronously, so that z _ji =1/z _ij .

Whenever an element greater than 1 in a corrected matrix Z is corrected, the corrected corrected matrix Z is checked for consistency; if the corrected matrix Z passes the consistency check, the corrected corrected matrix Z is corrected. If it does not pass the consistency check, continue to correct the next element in the corrected matrix Z; if all elements greater than 1 in the corrected matrix Z are corrected, the corrected matrix Z still fails the consistency check, then enter the step 6-4.

6-4. Re-execute the correction of steps 6-1 to 6-3 with the corrected matrix Z as the new corrected matrix Z until the corrected matrix Z passes the consistency detection.

Preferably, in step 3, a ₁₂ =2, a ₁₃ =5, and a ₂₃ =3.

其中，

为向上取整运算；ΔS为该两种被测液体的黏附面积的差值；S_l＝R_S/7。Preferably, the method for determining the characteristic ratio of the adhesion area of the two liquids to be tested is as follows: calculate the maximum area difference R _S =S _max -S _min ; S _max is the maximum value of the adhesion area of m kinds of liquids to be tested; S _min is m The minimum value of the adhesion area of the measured liquid; the characteristic ratio of the adhesion area between the measured liquid with a large adhesion area and the measured liquid with a small adhesion area is

in,

is the upward rounding operation; ΔS is the difference between the adhesion areas of the two tested liquids; S _l =R _S /7.

其中，ΔL为该两种被测液体的最大渗透深度的差值；L_l＝R_L/7。Preferably, the method for determining the maximum penetration depth characteristic ratio of the two tested liquids is as follows: calculate the maximum penetration depth difference R _L =L _max -L _min ; L _max is the maximum value of the maximum penetration depths of m kinds of tested liquids; L _min is the minimum value of the maximum penetration depth of m kinds of tested liquids; the characteristic ratio of trace length between the tested liquid with a larger maximum penetration depth and the tested liquid with a smaller maximum penetration depth is:

Wherein, ΔL is the difference between the maximum penetration depths of the two tested liquids; L _l =R _L /7.

其中，ΔF为该两种被测液体的相对运动摩擦力的差值；F_l＝R_S/7。Preferably, the method for determining the characteristic ratio of the lubricating properties of the two tested liquids is as follows: calculate the maximum frictional force difference R _F =F _max -F _min ; F _max is the difference between the magnitudes of the frictional forces after lubrication when m kinds of tested liquids are tested Maximum value; F _min is the minimum value of the friction force after lubrication when m kinds of tested liquids are tested; the lubricating performance between the tested liquid with larger relative motion friction and the tested liquid with smaller relative motion friction The characteristic ratio is

Among them, ΔF is the difference between the relative motion friction forces of the two measured liquids; F _l =R _S /7.

n为被检测矩阵的阶数；λ为被检测矩阵的特征根；引入随机一致性指标RI；RI的大小由被检测矩阵的阶数n决定；如下表所示；Preferably, the method for performing consistency detection on the matrix in step 5 is as follows: calculating the consistency index of the detected matrix

n is the order of the detected matrix; λ is the characteristic root of the detected matrix; the random consistency index RI is introduced; the size of RI is determined by the order n of the detected matrix; as shown in the following table;

若CR＜0.1，则被检测矩阵通过一致性检验；否则被检测矩阵未通过一致性检验。Calculate the consistency ratio

If CR<0.1, the detected matrix passes the consistency check; otherwise, the detected matrix fails the consistency check.

The invention discloses a spray-type micro-droplet dynamic wetting and lubricating characteristic detection device, comprising an atomized micro-droplet spraying component, a friction feeding component, a workpiece block and a tool block. The atomized droplet spraying assembly sucks the measured droplet and sprays it to the junction of the workpiece block and the tool block mounted on the friction feed assembly. The friction feeding assembly includes a linear module, a first connecting block, a pressure cylinder and a three-way force sensor. Linear modules are mounted on one side of the workpiece block. The first connecting plate is fixed on the sliding block of the linear module. The cylinder body of the pressure cylinder is fixed on the other side of the first connecting plate, and the piston rod is arranged downward. The tool block is installed on the bottom end of the piston rod of the pressure cylinder through a three-way force sensor; the tool block and the workpiece block are located on the same side of the linear module. The atomized droplet spraying assembly includes a water tank, a micro pump, a delivery pipe and an atomizing nozzle. The atomizing nozzle is mounted on the first connecting block and faces the gap between the tool block and the workpiece block. The water inlet of the atomizing nozzle is connected with the water outlet of the water tank through a micro pump and a conveying pipe.

Preferably, the apparatus for detecting the dynamic wetting and lubricating characteristics of spray-type micro-droplets of the present invention further includes a visual inspection system. The visual inspection system includes a maximum penetration depth detection camera, an adhesion area detection camera and a data processing unit. The maximum penetration depth detection camera is fixed on the first connection block, and the lens is vertically downward; the tool block droplet adhesion area detection camera is installed at one end of the workpiece block through the connection block, and the lens is vertically upward. When performing the maximum penetration depth detection, the lens of the maximum penetration depth detection camera is directly above the workpiece block. When the adhesion area inspection is performed, the tool block is located directly above the lens of the adhesion area inspection camera. The data output lines of the maximum penetration depth detection camera and the adhesion area detection camera are all connected with the data processing unit. The data processing unit uses a computer.

Preferably, a three-way force sensor is installed between the tool block and the piston rod of the pressure cylinder.

The beneficial effects that the present invention has are:

1. The present invention establishes an analytic hierarchy process model based on the adhesion area, maximum penetration depth and lubrication effect of the liquid to be measured, and provides an optimal wetting method suitable for different tools and workpiece materials in cutting through the calculation of the weight vector. Sexual cutting fluid selection method.

2. The invention uses the atomizing nozzle to obtain micro droplets with smaller size, which is more suitable for the micro-lubrication mode used in the actual processing process; it is more suitable for the detection of the penetration characteristics of micro-droplets under the capillary effect between micro-scale slits . The dynamic wettability detection process of micro-droplets is realized through a high-precision sliding stage.

3. The present invention simplifies the cutting process, and simulates the action process of the cutting fluid droplets on the tool-workpiece contact surface under the condition of minimal lubrication. The device is simple and convenient to operate and has wide adaptability.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present invention;

Fig. 2 is the schematic diagram of the maximum penetration depth of the measured liquid on the workpiece block in the present invention;

FIG. 3 is a schematic diagram of the adhesion area of the liquid to be tested on the tool block in the present invention.

FIG. 4 is a schematic diagram of the hierarchical structure of the hierarchical selection method in the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

As shown in Figure 1, a spray-type micro-droplet dynamic wetting and lubricating characteristic detection device includes a base plate, an atomized micro-droplet spraying component, a friction feeding component, a workpiece block 12, and a visual inspection system. The water tank in the atomized droplet spraying component is arranged side by side with the friction feed component; the atomized droplet spray component absorbs the measured droplets and sprays them to the junction of the tool block 9 and the workpiece block 12 of the friction feed component. The friction feed assembly is aligned with the workpiece block 12 . The tool block 9 and the workpiece block 12 of the friction feed assembly perform a relative friction motion while spraying the atomized droplets, so that the droplets move relative to each other during the friction process, forming liquid traces.

As shown in FIG. 1 , the friction feeding assembly includes a linear module 1 , a first connecting block 3 , a pressure cylinder 6 and a three-way force sensor 8 . The workpiece block 12 is fixed on the base plate. The linear module 1 is mounted on one side of the workpiece block 12 . One side of the first connecting plate 3 is fixed on the sliding block of the linear module 1 . The cylinder body of the pressure cylinder 6 is fixed on the other side of the first connecting plate 3, and the piston rod is arranged downward. The three-way force sensor 8 is installed at the bottom end of the piston rod of the pressure cylinder 6 ; the tool block 9 is installed at the bottom of the three-way force sensor 8 ; the tool block 9 and the workpiece block 12 are located on the same side of the linear module 1 . When the tool block 9 and the workpiece block 12 are in contact and pressed against each other, the three-way force sensor 8 can detect the pressing force between the tool block 9 and the workpiece block 12 . The area of the top surface of the workpiece block 12 is larger than the area of the bottom surface of the tool block 9 .

As shown in FIG. 1 , the atomized droplet spraying assembly includes a water tank 2 , a conveying pipe 4 , a conveying pipe support 7 , a cover 9 and an atomizing nozzle 10 . The water tank 2 is fixed on the bottom plate, and a micro-pump is installed in the water tank, and the spraying flow of the measured liquid is controlled by adjusting the output pressure of the micro-pump. The conveying pipe bracket 7 is in an inverted U shape, one end is fixed to the first connecting block 3 , and the other end is located on the side of the cutter block 9 away from the linear module 1 and is installed with an atomizing nozzle 10 . The atomizing nozzle 10 faces the gap between the tool block 9 and the workpiece block 12 . The water inlet of the atomizing nozzle 10 is connected with the water outlet of the water tank 2 through the conveying pipe 4 , so that the measured liquid in the water tank 2 is delivered to the atomizing nozzle 10 . The delivery tube 4 is arranged along the delivery tube holder 7 .

The visual inspection system includes a maximum penetration depth detection camera 5, an adhesion area detection camera 13 and a data processing unit. The maximum penetration depth detection camera 5 of the workpiece block droplet is fixed on the first connecting block 3, and the lens is vertically downward; the tool block droplet adhesion area detection camera 13 is fixed on the base plate through the connecting block, and the lens is vertically upward. When detecting the maximum penetration depth of droplets, the lens of the maximum penetration depth detection camera 5 is directly above the workpiece block 12 , and can capture the traces of the relative movement of the droplets, thereby obtaining the penetration depth of the droplets through image processing. When the droplet adhesion area detection is performed, the tool block moves to the top of the lens of the droplet adhesion area detection camera 13, and the droplet adhesion area detection camera 13 can capture the traces of the relative movement of the droplets, so as to obtain the liquid droplets through image processing. Adhesion area on the tool block.

The testing method for the dynamic wetting and lubricating characteristics of the spray-type micro-droplets is as follows:

Step 1: Carry out a spray-type minimal lubrication cutting simulation test for the three tested liquids according to the methods in steps 2 to 5.

Step 2: The linear module 1 drives the tool block 9 to move above the workpiece block 12 , so that the tool block 9 moves to the edge above the workpiece block.

Step 3: The pressure cylinder is ventilated, so that the bottom surface of the tool block 9 and the part of the top surface of the workpiece block 12 are closely attached together, and a preset pressing force is achieved between the two.

Step 4: The conveying pipe sucks the liquid to be tested from the water tank and sprays it into the connection interface between the workpiece block and the tool through the atomizing nozzle 11 . The measured droplet penetrates into the gap between the tool block 9 and the workpiece block 12; the linear module 1 drives the tool block 9 to move above the adhesion area detection camera 13, so that the tool block 9 and the workpiece block 12 perform relative friction motion; During the friction process, the pressure and friction force between the tool block 9 and the workpiece block 12 are fed back in real time by the three-way force sensor 8 .

Step 5. After the tool block 9 is separated from the workpiece block 12, the adhesion area detection camera 13 captures the traces of the measured liquid remaining on the bottom surface of the tool block 9. After the detection is completed, the tool block performs a reset motion. During the reset process, the maximum penetration depth detection camera 5 captures the traces of the measured liquid remaining on the top surface of the workpiece block 12 . The data processing unit extracts the maximum adhesion area S and the penetration depth Max from the two obtained photos, respectively;

Since the bottom surface area of the tool block 9 is smaller than the top surface area of the workpiece block 12 , a reference line is defined on the top surface of the workpiece block 12 , and the reference line is aligned with the edge of the tool block 9 near the atomizing nozzle 11 . The reference line is the edge boundary of the contact surface between the tool block and the workpiece block;

(1) When calculating the maximum penetration depth, take the distance from the deepest penetration point of the tested liquid on the workpiece block 12 to the reference line as the maximum penetration depth of the tested liquid as shown in Figure 2;

(2) When calculating the adhesion area, take the area of the liquid to be measured on the tool block 9 as the adhesion area of the liquid to be measured;

Step 5. Both the pressure cylinder 6 and the linear module 1 are reset.

Step 6. Based on the AHP, the evaluation process of the dynamic wetting characteristics of the tested liquid is divided into three levels: the bottom layer is the solution layer, which is composed of three tested liquids; the middle layer is the criterion layer, which is composed of the measured adhesion layer. area, maximum penetration depth, and friction force after lubrication; the above three criteria are composed of factors U={U ₁ , U ₂ , U ₃ }, where U ₁ is the liquid adhesion area, U ₂ is the maximum penetration depth of the liquid, and U ₃ friction force after lubrication. The top layer is the target layer, that is, the best dynamic wetting characteristics of the tested liquid. The overall evaluation structure is shown in Figure 4.

Step 7: Construct the judgment matrix A of the criterion layer to the target layer. The liquid adhesion area, the maximum penetration depth of the liquid, and the friction force after lubrication are taken as the first, second, and third factors, respectively; the importance and influence ratios between the three factors in the criterion layer are set respectively; the matrix A is as follows: (1).

a_ij越大表示第i个因素相较于第j个因素越重要；本实施例中，a₁₁＝a₂₂＝a₃₃＝1，a₁₂＝2，a₁₃＝5，a₂₃＝3。In formula (1), a _ij represents the importance influence ratio between the i-th factor and the j-th factor, i=1, 2, 3, j=1, 2, 3; a _ij >0,

A larger a _ij indicates that the i th factor is more important than the j th factor; in this embodiment, a ₁₁ =a ₂₂ =a ₃₃ =1, a ₁₂ =2, a ₁₃ =5, and a ₂₃ =3.

Calculate the weight vector ω _a =[ω _a1 ,ω _a2 ,ω _a3 ] ^T of the matrix A and the largest eigenroot λ _a .

Step 8: Constructing the judgment matrix B, C, D of the scheme layer to the target layer. According to the size of the adhesion area of the three tested liquids on the tool block 9, the characteristic ratio of the adhesion area between the three tested liquids is determined, and the matrix B is established as shown in formula (2). According to the maximum penetration depth of the three tested liquids on the workpiece block, the maximum penetration depth characteristic ratio between the three tested liquids is determined, and the matrix C is established as shown in formula (3). According to the friction force after lubrication of the three tested liquids, the characteristic ratio of the lubrication effect between the three tested liquids is determined, and the matrix D is established as shown in formula (4).

Among them, b _xy represents the characteristic ratio of the adhesion area between the x-th tested liquid and the y-th tested liquid; c _xy represents the maximum penetration depth characteristic ratio of the x-th tested liquid to the y-th tested liquid; d _xy represents The characteristic ratio of the lubricating effect of the xth tested liquid to the yth tested liquid; x=1,2,3, y=1,2,3.

The method for determining the adhesion area characteristic ratio b _xy of the two tested liquids is as follows:

其中，

为向上取整运算；ΔS为该两种被测液体的黏附面积的差值(正数)；S_l＝R_S/7。Calculate the maximum area difference R _S =S _max -S _min ; S _max is the maximum value of the adhesion area of the three tested liquids; S _min is the minimum value of the adhesion area of the three tested liquids; in the two tested liquids, The characteristic ratio of the adhesion area between the measured liquid with a larger adhesion area and the measured liquid with a smaller adhesion area is:

in,

is an upward rounding operation; ΔS is the difference (positive number) of the adhesion areas of the two tested liquids; S _l =R _S /7.

The determination method of the maximum penetration depth characteristic ratio c _xy of the two tested liquids is as follows:

其中，

为向上取整运算；ΔL为该两种被测液体的最大渗透深度的差值(正数)；L_l＝R_L/7。Calculate the maximum penetration depth difference R _L =L _max -L _min ; L _max is the maximum value of the maximum penetration depths of m kinds of tested liquids; L _min is the minimum value of the maximum penetration depths of three tested liquids; In the liquid, the characteristic ratio of the maximum penetration depth between the tested liquid with a larger maximum penetration depth and the tested liquid with a smaller maximum penetration depth is:

in,

is an upward rounding operation; ΔL is the difference (positive number) of the maximum penetration depths of the two tested liquids; L _l =R _L /7.

The method for determining the characteristic ratio of the lubricating properties of the two tested liquids is as follows:

其中，

为向上取整运算；ΔF为该两种被测液体的相对运动摩擦力的差值(正数)；F_l＝R_F/7。Calculate the maximum friction force difference R _F =F _max -F _min ; F _max is the maximum value of the average friction force after lubrication when the three tested liquids are tested; F _min is the average after lubrication when the three tested liquids are tested The minimum value of the friction force; among the two tested liquids, the lubricating performance characteristic ratio between the tested liquid with larger relative motion friction and the tested liquid with smaller relative motion friction is:

in,

is the upward rounding operation; ΔF is the difference (positive number) of the relative motion friction force of the two measured liquids; _{F l} =RF /7.

b₁₃＝3、b₂₃＝7；最大渗透深度的成对比较结果为：

c₁₃＝4、c₂₃＝7；平均摩擦力的成对比较结果为：

d₁₃＝4、d₂₃＝7。For example, the spray flow rate of the three liquids is 18ml/min, and the detection is carried out. The test results are as follows: adhesion area: 8.232cm ² , 9.130cm ² , 7.674cm ² ; maximum penetration depth: 10.2mm, 11.5mm, 8.4mm; average friction force: 39.20N, 38.09N, 39.48N. Then the pairwise comparison result of the adhesion area is:

b ₁₃ =3, b ₂₃ =7; the pairwise comparison results of the maximum penetration depth are:

c ₁₃ =4, c ₂₃ =7; the pairwise comparison results of the average friction force are:

d ₁₃ =4, d ₂₃ =7.

Calculate the weight vectors ω _b =[ω _b1 ,ω _b2 ,ω _b3 ] ^T , ω _c =[ω _c1 ,ω _c2 ,ω _c3 ] ^T ,ω _d =[ω _d1 ,ω _{d2 respectively} ,ω _d3 ] ^T and the largest eigenvalues λ _b , λ _c , λ _d .

Step 9: Perform consistency testing on matrices A, B, C, and D respectively, and correct the matrices that fail the consistency testing according to the method in step 10; if matrices A, B, C, and D all pass the consistency check , then go directly to step eleven.

The method to perform consistency check on a matrix is as follows:

n为被检测矩阵的阶数；λ为被检测矩阵的最大特征根；若一致性指标CI＝0，则被检测矩阵有完全的一致性；若CI接近于0即表示被检测矩阵有满意的一致性；CI越大，被检测矩阵的不一致越严重。为衡量一致性指标，引入随机指标RI；RI的大小由被检测矩阵的阶数决定；如下表所示；本实施例中矩阵A、B、C、D均为三阶矩阵，故RI均取0.58。Calculate the consistency index of the detected matrix

n is the order of the detected matrix; λ is the largest characteristic root of the detected matrix; if the consistency index CI=0, the detected matrix has complete consistency; if CI is close to 0, it means that the detected matrix has satisfactory Consistency; the larger the CI, the more severe the inconsistency of the detected matrix. In order to measure the consistency index, random index RI is introduced; the size of RI is determined by the order of the detected matrix; 0.58.

若CR＜0.1，则被检测矩阵的不一致程度在允许范围之内，通过一致性检验；否则被检测矩阵未通过一致性检验。Calculate the consistency ratio

If CR<0.1, the inconsistency of the detected matrix is within the allowable range, and the consistency check is passed; otherwise, the detected matrix fails the consistency check.

Step 10: Define each matrix A, B, C or D that fails the consistency check as the corrected matrix Z, and make corrections to make it pass the consistency check. The process of correcting the corrected matrix Z is as follows:

10-1: Construct the consistency matrix W according to the weight vector ω _z =[ω _z1 ,ω _z2 ,ω _z3 ] ^T of the corrected matrix Z (that is, the weight vector of the corrected matrix A, B, C or D) such as Formula (5) is shown;

10-2: Calculate the perturbation matrix P as shown in formula (6);

In formula (6), z _ij is the element of the i-th row and the j-th column of the corrected matrix Z.

本实施例中n＝3。Sort the absolute value |p _ij | of the off-diagonal elements in the perturbation matrix P from large to small; p _ij represents the element of the i-th row and the j-th column of the perturbation matrix P, and obtain the sorting result

In this embodiment, n=3.

10-3: According to the order of the absolute value of the elements in the perturbation matrix P from large to small, sort the elements of each corresponding position in the corrected matrix Z; then modify the elements greater than 1 in the corrected matrix Z in sequence; The conditions for correction are: if the element to be corrected zi _ij >1, zi _ij ≠2 and p _ij >0, then reduce zi _ij by one scale value, that is, reduce 1 by 1. If zi _ij >1, zi _ij ≠9 and p _ij <0, then increase zi _ij by a scale value, that is, increase 1; otherwise, zi _ij remains unchanged. When an element zi _ij greater than 1 in the corrected matrix Z is corrected, the element z _ji at the diagonal position of the element in the corrected matrix Z is corrected synchronously, so that z _ji =1/z _ij , so that the corrected corrected The matrix Z is still a reciprocal matrix.

Whenever an element greater than 1 in a corrected matrix Z is corrected, the corrected corrected matrix Z is checked for consistency; if the corrected matrix Z passes the consistency check, the correction of the corrected matrix Z is completed and the Weight vector, the corrected matrix Z is the corrected result of matrix A or B or C or D that fails the consistency check. If it does not pass the consistency check, continue to correct the next element in the corrected matrix Z; if all elements greater than 1 in the corrected matrix Z are corrected, the corrected matrix Z still fails the consistency check, then enter the step 10-4.

For step 10-3, for example, if l ₁ corresponds to the corresponding element in the perturbation matrix P is p ₁₂ ; then z ₂₁ and z ₁₂ are first corrected, and a consistency check is performed.

10-4. Re-execute the corrections of steps 10-1 to 10-3 with the corrected corrected matrix Z as the new corrected corrected matrix Z, until the corrected corrected matrix Z passes the consistency detection.

Step 11: Calculate the weight vector ω of each scheme to the target, as shown in formula (7).

Among them, the weight eigenvalues ω ₁ , ω ₂ , and ω ₃ correspond to the three tested liquids respectively; the larger the weight eigenvalue is, the better the dynamic wetting characteristics of the corresponding tested liquid. Advantages and disadvantages of dynamic wetting characteristics.

After the weight eigenvalues ω ₁ , ω ₂ , and ω ₃ are normalized, they represent the weights of the dynamic wetting characteristics of the three tested liquids to the target layer.

Claims (10)

1. A method for detecting the dynamic wetting and lubricating characteristics of spray-type micro-droplets is characterized by comprising the following steps: step one, performing spray type lubrication cutting simulation tests on m types of tested liquid respectively to obtain the adhesion area, the maximum penetration depth and the friction force after lubrication of the tested liquid;

the method for performing the minimal quantity lubrication test on the tested liquid comprises the following steps: the cutter block is contacted with the workpiece block, pretightening force is applied to the cutter block and the workpiece block, the cutter block and the workpiece block move in a relative friction mode, and meanwhile, an atomized liquid to be detected is applied to the junction of the cutter block and the workpiece block through an atomizing nozzle which slides along with the cutter block; the adhesion area is the area of the measured liquid adhered to the cutter block or the workpiece block after the relative friction motion is finished; the maximum penetration depth is the maximum depth of the measured liquid penetrating into the contact surface of the cutter block and the workpiece block after the relative friction motion is finished; the friction force after lubrication is the average friction force during relative friction movement;

step two, based on an analytic hierarchy process, dividing the dynamic wetting characteristic evaluation process of the detected liquid into three levels: the lowest layer is a scheme layer and consists of m kinds of tested liquid; the middle layer is a standard layer and consists of the measured liquid adhesion area, the maximum penetration depth and the friction force after lubrication; the uppermost layer is a target layer, namely the judged optimal dynamic wetting characteristic of the measured liquid;

thirdly, constructing a judgment matrix A of the criterion layer to the target layer; the adhesion area, the maximum penetration depth and the friction force after lubrication are respectively taken as three factors; respectively setting the importance influence ratio between every two of the three factors of the criterion layer;

establishing a matrix A as shown in a formula (1);

in the formula (1), a_ijRepresenting the importance influence ratio between the ith factor and the jth factor, i is 1,2,3, j is 1,2,3,

a_ijlarger means that the ith factor is more important than the jth factor;

computing the weight vector omega of the matrix A_a＝[ω_a1,ω_a2,ω_a3]^TAnd maximum characteristic root λ_a；

Step four, constructing a judgment matrix B, C, D of the scheme layer to the target layer; determining the characteristic ratio of the adhesion area between every two m kinds of measured liquid according to the sizes of the adhesion areas of the m kinds of measured liquid, and establishing a matrix B as shown in a formula (2); determining the maximum penetration depth characteristic ratio between every two m kinds of measured liquid according to the maximum penetration depth of the m kinds of measured liquid, and establishing a matrix C as shown in a formula (3); determining the lubricating effect characteristic ratio between m tested liquids according to the friction force after lubrication during the test of the m tested liquids, and establishing a matrix D as shown in the formula (4);

wherein, b_xyRepresenting the characteristic ratio of the adhesion area of the x type tested liquid and the y type tested liquid; c. C_xyRepresenting the characteristic ratio of the maximum penetration depth of the x tested liquid and the y tested liquid; d_xyRepresenting the characteristic ratio of the lubricating effect of the x tested liquid and the y tested liquid; x is 1,2, …, m, y is 1,2, …, m;

separately calculate the weight vector ω of the matrix B, C, D_b＝[ω_b1,ω_b2,...,ω_bm]^T、ω_c＝[ω_c1,ω_c2,...,ω_cm]^T、ω_d＝[ω_d1,ω_d2,...,ω_dm]^TAnd maximum characteristic root λ_b、λ_c、λ_d；

Step five, consistency detection is respectively carried out on the matrixes A, B, C, D; if the matrixes A, B, C, D all pass the consistency check, directly entering the step seven;

step six, correcting the matrix A, B, C or D which does not pass the consistency detection to ensure that the matrix passes the consistency detection;

step seven, calculating a weight vector omega of each scheme to the target as shown in the formula (7);

weight eigenvalue omega₁,ω₂,...,ω_mRespectively correspond to m kinds of quiltsMeasuring the liquid; the larger the weight characteristic value is, the more excellent the dynamic wetting characteristics of the corresponding measured liquid is, and thereby the advantages and disadvantages of the dynamic wetting characteristics of the m kinds of measured liquids are obtained.

2. The method for detecting the dynamic wetting and lubricating properties of the sprayed micro-droplets according to claim 1, wherein the method comprises the following steps: in the sixth step, the matrix A, B, C or D which does not pass the consistency detection is defined as a corrected matrix Z; the process of correcting the corrected matrix Z is as follows:

6-1: the weight vector omega according to the modified matrix Z_z＝[ω_z1,ω_z2,...,ω_zn]^TConstructing a consistency matrix W as shown in formula (5);

6-2: calculating a disturbance matrix P as shown in formula (6);

P＝Z-W (6)

6-3: sequencing the elements at each corresponding position in the corrected matrix Z according to the sequence of the absolute values of the non-diagonal elements in the disturbance matrix P from large to small; then, sequentially correcting elements which are larger than 1 in the corrected matrix Z according to the sequence; the correction conditions are as follows: if corrected element z_ijNot equal to 2 and p_ijIf > 0, then z is_ijDecrease by 1; if z is_ijNot equal to 9 and p_ij<0, then z is_ijIncreasing by 1; otherwise, z_ijKeeping the same; when an element Z greater than 1 is present in the modified matrix Z_ijWhen corrected, the element Z of the diagonal position of the element in the corrected matrix Z is synchronously corrected_jiSo that z is_ji＝1/z_ij；

When one element which is larger than 1 in one corrected matrix Z is corrected, consistency detection is carried out on the corrected matrix Z; if the consistency detection is passed, the correction of the corrected matrix Z is completed; if the consistency detection is not passed, continuously correcting the next element in the corrected matrix Z; if all elements larger than 1 in the corrected matrix Z are corrected, and the corrected matrix Z still does not pass consistency detection, entering the step 6-4;

6-4, the corrected matrix Z is taken as a new corrected matrix Z to re-execute the correction of the steps 6-1 to 6-3 until the corrected matrix Z passes the consistency detection.

3. In the third step of the method for detecting the dynamic wetting and lubricating properties of the spray-type micro-droplets according to claim 1, a₁₂＝2，a₁₃＝5，a₂₃＝3。

4. The method for detecting the dynamic wetting and lubricating properties of the spray-type micro-droplets as claimed in claim 1, wherein the ratio of the two measured liquid adhesion area characteristics is determined by the following steps: calculating the maximum area difference R_S＝S_max-S_min；S_maxThe maximum value of the adhesion area of the m tested liquids; s_minThe minimum value of the adhesion areas of the m tested liquids; the characteristic ratio of the adhesion area between the measured liquid with larger adhesion area and the measured liquid with smaller adhesion area is

Wherein,

is an upward rounding operation; Δ S is the difference in the adhesion area of the two measured liquids; s_l＝R_S/7。

5. The method for detecting the dynamic wetting and lubricating characteristics of the spray-type micro-droplets according to claim 1 comprises the following steps of: calculating the maximum penetration depth difference R_L＝L_max-L_min；L_maxThe maximum value of the maximum penetration depth of the m tested liquids; l is_minThe minimum value of the maximum penetration depth of the m tested liquids; the characteristic ratio of the length of the trace between the measured liquid with the larger maximum penetration depth and the measured liquid with the smaller maximum penetration depth is

Wherein, the delta L is the difference value of the maximum penetration depth of the two measured liquids; l is_l＝R_L/7。

6. The method for detecting the dynamic wetting and lubricating characteristics of the spray type micro-droplets as claimed in claim 1 comprises the following steps: calculating the maximum friction difference R_F＝F_max-F_min；F_maxThe maximum value of the friction force after lubrication in the test of the m tested liquids; f_minThe minimum value of the friction force after lubrication in the test of the m tested liquids; the characteristic ratio of the lubricating performance between the measured liquid with large relative kinetic friction and the measured liquid with small relative kinetic friction is

Wherein, Δ F is the difference of the relative kinetic friction of the two measured liquids; f_l＝R_S/7。

7. The method for detecting the dynamic wetting and lubricating properties of the sprayed micro-droplets according to claim 1, wherein the method for detecting the consistency of the matrix in step five comprises the following steps: calculating consistency index of detected matrix

n is the order of the detected matrix; lambda is a characteristic root of the detected matrix; introducing a random consistency index RI; the RI is determined by the order number n of the detected matrix; as shown in the following table;

calculating a consistency ratio

If CR is less than 0.1, the detected matrix passes consistency check; otherwise, the detected matrix fails the consistency check.

8. A spray type micro-droplet dynamic wetting lubrication characteristic detection device comprises an atomized micro-droplet spraying assembly, a friction feeding assembly, a workpiece block and a cutter block; the method is characterized in that: the atomized micro-droplet spraying assembly absorbs the measured droplets and sprays the droplets to the junction of the workpiece block and the cutter block arranged on the friction feeding assembly; the friction feeding assembly comprises a linear module, a first connecting block, a pressure cylinder and a three-way force sensor; the linear module is arranged on one side of the workpiece block; the first connecting plate is fixed on a sliding block of the linear module; the other side of the first connecting plate is fixed on the cylinder body of the pressure cylinder, and the piston rod is arranged downwards; the cutter block is arranged at the bottom end part of a piston rod of the pressure cylinder through a three-way force sensor; the cutter block and the workpiece block are positioned on the same side of the linear module; the atomized micro-droplet spraying assembly comprises a water tank, a micro pump, a conveying pipe and an atomizing nozzle; the atomizing nozzle is arranged on the first connecting block and faces to a gap between the cutter block and the workpiece block; the water inlet of the atomizing nozzle is connected with the water outlet of the water tank through a micro pump and a delivery pipe.

9. The device for detecting the dynamic wetting and lubricating characteristics of the sprayed micro-droplets according to claim 8, wherein: a visual inspection system is also included; the visual detection system comprises a maximum penetration depth detection camera, an adhesion area detection camera and a data processing unit; the maximum penetration depth detection camera is fixed on the first connecting block, and the lens is vertically downward; the cutter block liquid drop adhesion area detection camera is installed at one end of the workpiece block through a connecting block, and the lens is vertically upward; when the maximum penetration depth detection is carried out, the lens of the maximum penetration depth detection camera is positioned right above the workpiece block; when the adhesion area is detected, the cutter block is positioned right above the lens of the adhesion area detection camera; the data output lines of the maximum penetration depth detection camera and the adhesion area detection camera are connected with the data processing unit; the data processing unit adopts a computer.

10. The device for detecting the dynamic wetting and lubricating characteristics of the sprayed micro-droplets according to claim 8, wherein: and a three-way force sensor is arranged between the cutter block and a piston rod of the pressure cylinder.

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