A method for evaluating the drilling quality of CF / PEEK material workpieces

Abstract

The present invention discloses a method for evaluating the drilling quality of a CF / PEEK material workpiece. In the present invention, a drilling processing experiment is performed on a CF / PEEK material workpiece using various processing parameter combinations. The burr defect evaluation factor, tear defect evaluation factor, and delamination defect evaluation factor of each hole are calculated based on the burr defect data, tear defect data, and delamination defect data of each hole. A relationship between each evaluation factor and the material removal rate is established, and a hole quality evaluation formula is established using each evaluation factor. Each relationship is substituted into the evaluation formula, and the material removal rate is related to each processing parameter in the processing parameter combination. Then, an evaluation formula established by each processing parameter in the processing parameter combination is obtained, and the hole quality is evaluated using the evaluation formula using the preset processing parameter combination. The present invention can evaluate the hole quality on a CF / PEEK material workpiece based on the various processing parameters of the drilling process.

Description

Technical Field

[0001] The invention belongs to the field of drilling quality assessment, and in particular relates to a method for assessing the drilling quality of a CF / PEEK material workpiece. Background Art

[0002] CF / PEEK is a high-performance material that is lightweight, strong, and corrosion-resistant. It has excellent mechanical and chemical properties and is therefore widely used in many fields, particularly aviation. In the assembly of composite materials, mechanical connection methods such as bolting and riveting are the primary connection methods in the aerospace industry, and the processing quality of the connection holes is an important prerequisite for ensuring the reliability of the connection structure. However, due to the unique structure and characteristics of CF / PEEK, there are currently few evaluation indicators for the hole-forming quality of CF / PEEK materials, and related hole quality assessment methods are mainly based on the inspection data of the formed holes. Research on hole quality has not yet been linked to the drilling process, and there is no relevant hole quality assessment method. Therefore, a method is needed to evaluate the drilling quality of CF / PEEK materials based on drilling processing parameters. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and propose a method for evaluating the drilling quality of CF / PEEK material workpieces.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for evaluating the drilling quality of CF / PEEK workpieces is as follows:

[0006] Step 1. Set the processing parameters for the drilling processing experiment, including the speed n, feed rate f, and drilling radius r; set the parameter range of the speed n and feed rate f, select multiple parameter nodes within each parameter range, and select multiple drill bits with different diameters. Parameter combinations of different speeds n, feed rates f, and drilling radii r are obtained to obtain multiple processing parameter combinations. Use each processing parameter combination and a drill bit of the corresponding diameter to perform a drilling processing experiment on a CF / PEEK material workpiece.

[0007] Step 2: Perform data detection on the holes obtained under each combination of processing parameters to obtain the area of ​​burr defects and tear defects at the exit position of each hole on the CF / PEEK material workpiece, as well as the area of ​​delamination defects of each layer at the position of each hole on the CF / PEEK material workpiece.

[0008] Step 3: Calculate the evaluation factor of burr defects under each processing parameter combination based on the burr defect area, tear defect area and delamination defect area of ​​each hole Evaluation factors of tear defects and evaluation factor F of delamination defectv .

[0009] Step 4: Calculate the material removal rate under each combination of processing parameters. The calculation formula for material removal rate is:

[0010] x=A×f v

[0011] Where x is the material removal rate, A is the cross-sectional area of ​​the hole, and A = πr 2 , f v is the feed rate, and f v =f·n;

[0012] The relationship equations between the evaluation factors of burr defects, tear defects, and delamination defects and the material removal rate are defined respectively. Regression analysis is performed between the material removal rate under each combination of processing parameters and the corresponding evaluation factors of burr defects, tear defects, and delamination defects to obtain the values ​​of each coefficient in each relationship equation.

[0013] Step 5: Establish the hole quality evaluation formula based on the evaluation factors of burr defects, tear defects and delamination defects, which is:

[0014]

[0015] Where, is the evaluation index of hole quality, α, β and γ are the weight coefficients of burr defect, tear defect and delamination defect, respectively, α+β+γ=1, and the influence of delamination defect, burr defect and tear defect on hole quality gradually decreases, γ>α>β.

[0016] Substituting the relationship between the evaluation factors of burr defects, tear defects and delamination defects and the material removal rate into the above formula, the hole quality evaluation formula established by the material removal rate is obtained, and then the hole quality evaluation formula established by each processing parameter is obtained. The hole quality evaluation formula established by each processing parameter is used to predict the quality evaluation index of the hole under the preset parameter combination. like If the value exceeds the preset value, it means that the hole quality under the preset parameter combination meets the requirements, otherwise it does not meet the requirements.

[0017] Preferably, the detection process of step 2 is: taking pictures of the CF / PEEK material workpiece that has completed the drilling processing experiment through an ultra-depth of field microscope, obtaining burr defect images and tear defect images at the exit positions of each hole on the CF / PEEK material workpiece, and identifying each image to obtain the corresponding position and pixel area of ​​the burr defect and tear defect at the exit position of each hole, and then ultrasonically scanning the delamination of each layer at each hole position on the CF / PEEK material workpiece to obtain the delamination defect area of ​​each layer at each hole position.

[0018] Preferably, the evaluation factor of the burr defect is

[0019]

[0020] Where A bi is the total area of ​​burr defects, A nom is the theoretical area of ​​the hole;

[0021] The evaluation factor of tearing defect is

[0022]

[0023] Where m is the number of tearing segments of the hole, A si is the area of ​​the tear in the i-th segment;

[0024] The evaluation factor of delamination defect is

[0025]

[0026] Where p is the number of layers of the CF / PEEK workpiece, is the stratification factor of the kth layer, and is the delamination defect area of ​​the kth layer.

[0027] Preferably, the relationship between the material removal rate and the burr defect evaluation factor is:

[0028]

[0029] The data of the material removal rate and the corresponding burr defect evaluation factor under each combination of processing parameters are fitted to obtain the values ​​of coefficients a, b, c, and d, and then the relationship between the material removal rate and the burr defect evaluation factor is obtained;

[0030] The relationship between material removal rate and tearing defect evaluation factor is:

[0031]

[0032] The material removal rate under each combination of processing parameters and the data of the corresponding tear defect evaluation factor are fitted to obtain the values ​​of coefficients k and t, and then the relationship between the material removal rate and the tear defect evaluation factor is obtained;

[0033] The relationship between material removal rate and delamination defect evaluation factor is:

[0034] F v =F v0 +B×exp(-0.5×((xx c ) / w) 2 )

[0035] The material removal rate under each combination of processing parameters is fitted with the data of the corresponding delamination defect evaluation factor to obtain the coefficient F v0 , B, x c and w, and then the relationship between material removal rate and tearing defect evaluation factor is obtained.

[0036] More preferably, the hole quality evaluation formula established by the material removal rate is:

[0037]

[0038] The present invention has the following beneficial effects:

[0039] The present invention can evaluate the hole quality of a CF / PEEK material workpiece based on various processing parameters of drilling processing, thereby avoiding waste of the CF / PEEK material workpiece and saving costs. Specifically, the present invention uses the set processing parameter combinations to conduct drilling processing experiments on CF / PEEK material workpieces, and detects each hole to obtain burr defect data, tear defect data and delamination defect data of each hole, and then calculates the burr defect evaluation factor, tear defect evaluation factor and delamination defect evaluation factor of each hole based on each data, and then establishes a relationship between each processing parameter in the processing parameter combination and the material removal rate during the drilling process, and establishes a relationship between each evaluation factor and the material removal rate respectively, and then establishes a quality evaluation formula for the hole through each evaluation factor, and substitutes the relationship between each evaluation factor and the material removal rate into the evaluation formula, and then obtains the quality evaluation formula for the hole established by the material removal rate, thereby obtaining the quality evaluation formula for the hole established by each processing parameter in the processing parameter combination. The preset processing parameter combination can be used to evaluate the hole quality through the evaluation formula, without the need for drilling processing, avoiding the waste of CF / PEEK material workpieces, saving costs, and providing strong theoretical support for optimizing the processing technology, which has important theoretical and practical significance. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the embodiments.

[0041] The present invention provides a method for evaluating the drilling quality of a CF / PEEK material workpiece, which is specifically as follows:

[0042] Step 1. Set the processing parameters of the drilling processing experiment. The processing parameters include speed n, feed rate f and drilling radius r, where the drilling radius r is equal to the radius of the drill bit. In addition, the drilling holes involving CF / PEEK material workpieces are all short holes, so the influence of drilling depth on hole quality is not considered; set the parameter range of speed n and feed rate f, select multiple parameter nodes within each parameter range, and select multiple drill bits with different diameters, that is, multiple holes with different drilling radii can be processed, and parameter combinations of different speeds n, feed rates f and drill bit radii r are performed to obtain multiple processing parameter combinations. Use each processing parameter combination and the corresponding straight A drilling experiment was carried out on a CF / PEEK material workpiece using a drill bit of a certain diameter; in this embodiment, the parameter range of the speed n is 1000rpm~3000rpm, the parameter nodes of the speed n include 1000rpm, 1500rpm, 2000rpm, 2500rpm and 3000rpm, the parameter range of the feed rate f is 0.010mm / rev~0.030mm / rev, and the parameter nodes of the feed rate f include 0.010mm / rev, 0.015mm / rev, 0.020mm / rev, 0.025mm / rev and 0.030mm / rev.

[0043] Step 2. Perform data detection on the holes obtained under each combination of processing parameters: Use an ultra-depth-of-field microscope to photograph the CF / PEEK material workpiece that has completed the drilling processing experiment to obtain burr defect images and tear defect images at the exit positions of each hole on the CF / PEEK material workpiece, and identify each image to obtain the corresponding position and area of ​​the burr defect and tear defect at the exit position of each hole; then use ultrasonic scanning to scan the delamination of each layer at each hole position on the CF / PEEK material workpiece to obtain the delamination defect area of ​​each layer at each hole position.

[0044] Step 3: Calculate the evaluation factors of burr defects, tear defects and delamination defects under each combination of processing parameters according to the burr defect area, tear defect area and delamination defect area of ​​each hole. The evaluation factor of burr defect is

[0045]

[0046] Where, is the evaluation factor of burr defects, A bi is the total area of ​​burr defects, A nom is the theoretical area of ​​the hole;

[0047] The evaluation factor of tearing defect is

[0048]

[0049] Where, is the evaluation factor of tearing defect, m is the number of tearing segments of the hole, Asi is the area of ​​the tear in the i-th segment;

[0050] The evaluation factor of delamination defect is

[0051]

[0052] Where, F v is the evaluation factor of delamination defect, p is the number of delaminations of CF / PEEK material workpiece, is the stratification factor of the kth layer, and is the delamination defect area of ​​the kth layer.

[0053] Step 4: Calculate the material removal rate under each combination of processing parameters. The calculation formula for material removal rate is:

[0054] x=A×f v

[0055] Where x is the material removal rate, A is the cross-sectional area of ​​the drilled hole, and A = πr 2 , f v is the feed rate, and f v =f·n;

[0056] The material removal rate x includes various processing parameters. The material removal rate is used to replace each processing parameter, and the relationship between the evaluation factors of burr defects, tear defects, and delamination defects and the material removal rate is established:

[0057] The relationship between material removal rate and burr defect evaluation factor is defined as follows:

[0058]

[0059] The data of material removal rate and corresponding burr defect evaluation factor under various processing parameter combinations were used for regression analysis to obtain the values ​​of coefficients a, b, c and d, and then the relationship between material removal rate and burr defect evaluation factor was obtained;

[0060] The relationship between material removal rate and tearing defect evaluation factor is defined as

[0061]

[0062] The data of material removal rate and tear defect evaluation factor under each combination of processing parameters were used for regression analysis to obtain the values ​​of coefficients k and t, and then the relationship between material removal rate and tear defect evaluation factor was obtained;

[0063] The relationship between material removal rate and delamination defect evaluation factor is defined as

[0064] F v =F v0+B×exp(-0.5×((xx c ) / w) 2 )

[0065] The material removal rate under each combination of processing parameters and the corresponding delamination defect evaluation factor data were used for regression analysis to obtain the coefficient F v0 , B, x c and w, and then the relationship between material removal rate and tearing defect evaluation factor is obtained.

[0066] Step 5: Establish the hole quality evaluation formula based on the evaluation factors of burr defects, tear defects and delamination defects, which is:

[0067]

[0068] Where, is the quality evaluation index of the hole, α, β and γ are the weight coefficients of burr defect, tear defect and delamination defect respectively, α+β+γ=1;

[0069] Among them, the weight coefficients of burr defects, tear defects and delamination defects are determined according to the degree of influence of hole quality on CF / PEEK material workpieces. Delamination defects will lead to uneven hole wall thickness, seriously affecting the overall strength and sealing of the hole. Burr defects will significantly affect the dimensional accuracy and overall appearance of the hole, and may cause the fitting accuracy of the hole to decrease, causing potential performance problems of CF / PEEK material workpieces in high-load applications. Tearing defects may reduce the mechanical strength and durability of the hole, thereby affecting the long-term performance of the CF / PEEK material workpiece. However, due to the excellent strength and heat resistance of CF / PEEK material, tearing defects are less likely to occur during the processing. In summary, the degree of influence of delamination defects, burr defects and tearing defects on hole quality gradually decreases, then γ>α>β. In this embodiment, γ=0.4, α=0.35, β=0.25.

[0070] Substituting the relationship between the evaluation factors of burr defects, tear defects and delamination defects and material removal rate into the above formula, we can get

[0071]

[0072] Then, the hole quality evaluation formula established by the material removal rate is obtained, and then the hole quality evaluation formula established by each processing parameter is obtained. The hole quality evaluation index under the preset parameter combination is predicted by the hole quality evaluation formula established by each processing parameter. like If the value exceeds the preset value, it means that the hole quality under the preset parameter combination meets the requirements, otherwise it does not meet the requirements.

Claims

1. A method for evaluating the drilling quality of a CF / PEEK workpiece, characterized by: The details are as follows: Step 1: Set the processing parameters for the drilling experiment, including the speed n, feed rate f, and drilling radius r, where the drilling radius r is equal to the radius of the drill bit; set the parameter range of the speed n and feed rate f, select multiple parameter nodes within each parameter range, and select multiple drill bits of different diameters. Parameter combinations of different speed n, feed rate f, and drilling radius r are obtained to obtain multiple processing parameter combinations. Use each processing parameter combination and drill bits of corresponding diameters to conduct drilling experiments on CF / PEEK material workpieces; Step 2: Performing data detection on the holes obtained under each combination of processing parameters to obtain the area of ​​burr defects and tear defects at the exit position of each hole on the CF / PEEK material workpiece, as well as the area of ​​delamination defects of each layer at the position of each hole on the CF / PEEK material workpiece; Step 3: Calculate the evaluation factor of burr defects under each processing parameter combination based on the burr defect area, tear defect area and delamination defect area of ​​each hole Evaluation factors of tear defects and evaluation factor F of delamination defect v ; Step 4: Calculate the material removal rate under each combination of processing parameters. The calculation formula for material removal rate is: x=A×f v Where x is the material removal rate, A is the cross-sectional area of ​​the hole, and A = πr 2 , f v is the feed rate, and f v =f·n; The relationship between the evaluation factors of burr defects, tear defects, and delamination defects and the material removal rate is defined respectively. The material removal rate under each combination of processing parameters and the evaluation factors of the corresponding burr defects, tear defects, and delamination defects are used for regression analysis to obtain the values ​​of each coefficient in each relationship. Step 5: Establish the hole quality evaluation formula based on the evaluation factors of burr defects, tear defects and delamination defects, which is: Where, is the evaluation index of hole quality, α, β and γ are the weight coefficients of burr defect, tear defect and delamination defect respectively, α+β+γ=1, and the influence of delamination defect, burr defect and tear defect on hole quality gradually decreases, γ>α>β; Substituting the relationship between the evaluation factors of burr defects, tear defects and delamination defects and the material removal rate into the above formula, the hole quality evaluation formula established by the material removal rate is obtained, and then the hole quality evaluation formula established by each processing parameter is obtained. The hole quality evaluation formula established by each processing parameter is used to predict the quality evaluation index of the hole under the preset parameter combination. like If the value exceeds the preset value, it means that the hole quality under the preset parameter combination meets the requirements, otherwise it does not meet the requirements; The relationship between the burr defect evaluation factor and the material removal rate is: The data of material removal rate and corresponding burr defect evaluation factor under various processing parameter combinations were used for regression analysis to obtain the values ​​of coefficients a, b, c and d, and then the relationship between material removal rate and burr defect evaluation factor was obtained; The relationship between material removal rate and tearing defect evaluation factor is: The data of material removal rate and tear defect evaluation factor under each combination of processing parameters were used for regression analysis to obtain the values ​​of coefficients k and t, and then the relationship between material removal rate and tear defect evaluation factor was obtained; The relationship between material removal rate and delamination defect evaluation factor is: F v =F v0 +B×exp(-0.5×((x-x c ) / w) 2 ) The material removal rate under each combination of processing parameters and the corresponding delamination defect evaluation factor data were used for regression analysis to obtain the coefficient F v0 , B, x c and w values, and then the relationship between material removal rate and tear defect evaluation factor is obtained; The hole quality evaluation formula established by the material removal rate is:

2. The method for evaluating the drilling quality of a CF / PEEK workpiece according to claim 1, wherein: The detection process of step 2 is as follows: photographing the CF / PEEK material workpiece that has completed the drilling processing experiment through an ultra-depth-of-field microscope to obtain burr defect images and tear defect images at the exit positions of each hole on the CF / PEEK material workpiece, and identifying each image to obtain the corresponding position and pixel area of ​​the burr defect and tear defect at the exit position of each hole, and then ultrasonically scanning the delamination of each layer at the position of each hole on the CF / PEEK material workpiece to obtain the delamination defect area of ​​each layer at each hole position.

3. The method for evaluating the drilling quality of a CF / PEEK workpiece according to claim 1, wherein: The evaluation factor of the burr defect is Where A bi is the total area of ​​burr defects, A nom is the theoretical area of ​​the hole; The evaluation factor of tearing defect is Where m is the number of tearing segments of the hole, A si is the area of ​​the tear in the i-th segment; The evaluation factor of delamination defect is Where p is the number of layers of the CF / PEEK workpiece, is the stratification factor of the kth layer, and is the delamination defect area of ​​the kth layer.

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