Compensation method for spatial accuracy evaluation of gantry vertical machining center

Abstract

The application discloses a door type vertical machining center space precision evaluation compensation method, and specifically comprises the following steps: establishing an error model in combination with space precision influencing factors; constructing a space precision evaluation system; giving a machine tool space precision evaluation method in combination with the evaluation system; and analyzing error compensation according to the evaluation result to improve the space precision evaluation method; in the application, the space precision of a high-speed high-precision door type vertical machining center is analyzed in depth, influencing factors are discussed, and an effective evaluation method is proposed; a systematic precision evaluation process is provided in combination with space error model establishment and analysis, corresponding error compensation is carried out in combination with the evaluation result, and a theoretical basis and practical guidance are provided for improving the precision stability and machining quality of the machining center.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machine tool machining, in particular to a door type vertical machining center space precision evaluation compensation method. BACKGROUND

[0002] As a core indicator for evaluating the performance of machining centers, spatial precision is influenced by a variety of internal and external factors. Internal factors mainly include the structural design of the machine tool and the quality control during the manufacturing process. The rationality of the structural design is directly related to the rigidity and stability of the machine tool, which in turn affects the machining precision. For example, the design of the column and beam of the door type vertical machining center must ensure sufficient support force and minimal deformation. Material selection, heat treatment process and assembly precision during the manufacturing process are also key internal factors that affect precision.

[0003] External factors involve more extensive content. Changes in environmental temperature can cause thermal expansion or contraction of the machine tool structure, resulting in machining errors. Changes in humidity can also affect the physical properties of materials and lubrication conditions. In addition, vibrations and impact loads experienced by the machine tool during use can adversely affect its precision. The material properties and clamping methods of the workpiece itself also have an impact on the machining results. The existence of these external factors makes precision control more complex.

[0004] Affected by internal and external factors of the machine tool, the spatial precision of the machine tool will produce certain errors. Error types can be classified according to their manifestation and generation mechanism. Static errors usually refer to inherent deviations of the machine tool in the non-working state, such as straightness error of guide rail, radial runout of spindle, etc. These errors are relatively stable and can be reduced by calibration and compensation. Dynamic errors are generated during the operation of the machine tool, such as displacement errors caused by inertial forces due to accelerated motion, or vibration errors generated due to uneven stress during cutting. The randomness and complexity of dynamic errors make them more difficult to predict and control. Therefore, in-depth research and effective management of static and dynamic errors are crucial for improving the spatial precision of the machining center. SUMMARY

[0005] The main purpose of the present application is to provide a door type vertical machining center space precision evaluation compensation method, which aims to solve the existing technical problems.

[0006] To achieve the above purpose, the present application provides a door type vertical machining center space precision evaluation compensation method, which specifically includes the following steps,

[0007] Establish an error model combining the influencing factors of spatial precision;

[0008] Construct a spatial precision evaluation system;

[0009] The evaluation method of machine tool space precision is given in combination with the evaluation system;

[0010] According to the evaluation results, the error compensation is analyzed, and the space precision evaluation method is improved.

[0011] Further, the error model includes linear superposition of errors of each degree of freedom of the kinematic pair, simplification and combination of error elements of the three-axis precision CNC machine tool, and the specific steps are as follows,

[0012] When the workbench X-axis moves a distance x, there are 3 movement (geometric) errors δ yX , δ xX , δ zX , 3 rotation angle errors ε yX , ε xX , ε zX , 1 perpendicularity error S yX , 3 thermal drift errors δ xX (t), δ yX (t), δ zX (t) and 3 force errors δ xX (f), δ yX (f), δ zX (f), so the error transformation matrix of the reference coordinate system to the X-axis is:

[0013]

[0014] When the workbench Y-axis moves a distance y, there are 3 movement (geometric) errors δ yY , δ xY , δ zY , 3 rotation angle errors ε yY , ε xY , ε zY , 3 thermal drift errors δ xY (t), δ yY (t), δ zY (t) and 3 force errors δ xY (f), δ yY (f), δ zY (f), according to the coordinate transformation and the small error assumption theory, the transformation matrix of the Y-axis to the reference coordinate system is:

[0015]

[0016] When the workbench Z-axis moves a distance z, there are 3 movement (geometric) errors δ yZ , δ xZ , δ zZ , 3 rotation angle errors ε yz , ε xZ , ε zZ , 2 perpendicularity errors S xz, S yz , 3 items of thermal drift error δ xZ (t), δ yZ (t), δ zZ (t) and 3 items of force error δ xZ (f), δ yZ (f), δ zZ (f), the error transformation matrix of the reference coordinate system to the Z axis is:

[0017]

[0018] When the machine tool moves along the X axis, Y axis and Z axis by distances x, y and z respectively, the transformation matrix is

[0019]

[0020] Further, the evaluation system comprises fuzzy comprehensive evaluation, and the fuzzy comprehensive evaluation comprises,

[0021] According to the evaluation target, an evaluation index system is established, and an evaluation index set is extracted;

[0022] The index weight is determined;

[0023] The index membership function and the comprehensive evaluation mathematical model are constructed.

[0024] Further, the process of establishing the evaluation index system comprises gradually decomposing the evaluation target into sub-targets at each level according to the total target, the criterion layer and the index layer, so as to obtain an evaluation index system with a progressive structure, and the sub-targets at each level are collectively referred to as evaluation indexes, which describe different aspects of the evaluated object and characterize the features of the evaluated object.

[0025] Further, the evaluation system further comprises establishing a fuzzy relationship between the factor set U and the evaluation set V in the primary fuzzy comprehensive evaluation process In a limited domain, which can be represented by a matrix R, r ij = μ R (u i ,v j ), 0 ≤ r ij ≤ 1, representing the membership degree of a certain research object evaluated as v j from the factor u i , determining a weight vector W to obtain Y = WR, and performing result evaluation according to the value of Y.

[0026] Further, the evaluation system further comprises establishing a multi-level evaluation model, which comprises firstly performing primary comprehensive evaluation within each layer, and then performing comprehensive evaluation of a higher level between layers. The steps of multi-level fuzzy comprehensive evaluation are as follows:

[0027] (1) The factor set X = {x1, x2,..., x n} is divided into s subsets according to attributes,

[0028]

[0029] (2) A comprehensive decision is made for each sub-factor X i , and let y = {y1, y2,..., y m} be the evaluation set, and the weight distribution of each factor in X i is

[0030]

[0031] wherein

[0032]

[0033] If R i is a single-factor matrix, then a first-level evaluation vector is obtained

[0034]

[0035] (3) Each X i is regarded as a factor, and let

[0036] X = {X1, X2,..., X s}

[0037] The single-factor decision matrix of X is

[0038]

[0039] Each X i is given a weight distribution according to importance as part of X:

[0040] A = (a1, a2,..., a s )

[0041] Thus, we have

[0042] B = A·R = (b1, b2,..., b m )

[0043] Thus, a second-level fuzzy comprehensive evaluation model block diagram is obtained.

[0044] The first-level factor set X i is further subdivided, and thus a third-level fuzzy comprehensive evaluation model, a fourth-level fuzzy comprehensive evaluation model, and so on are obtained.

[0045] Further, the evaluation system comprises 3 levels, the first level is the overall target, i.e., the numerical control machine tool overall precision factor set U = {U1, U2}; the second level is the second-level target factor set Ui (i = 1, 2), wherein U1 is a static error factor set, U2 is a dynamic error factor set, U1 = {J 11 ,J 12 ,J 13 ,J 14 ,J 15 ,J 16} and U2 = {U 21 ,U 22 ,U 23}, the third layer is a third level target factor set U 2i (i = 1, 2, 3), wherein,

[0046] U 21 = {D 11 ,D 12 ,D 13 ,D 14 ,D 15 ,D 16}

[0047] U 22 = {D 21 ,D 22 ,D 23 ,D 24 ,D 25 ,D 26}

[0048] U 23 = {D 31 ,D 32 ,D 33 ,D 34 ,D 35 ,D 36}.

[0049] Further, the evaluation method comprises: obtaining a corresponding single-factor fuzzy comprehensive evaluation matrix according to the evaluation system

[0050]

[0051] Substitute the obtained results into the evaluation matrix to obtain a two-level fuzzy evaluation matrix R 21 and a three-level fuzzy evaluation matrix R 31 , R 32 , R 33 , the two-level index fuzzy comprehensive evaluation result can be obtained from the dynamic error three-level index weight vector, and then the overall comprehensive evaluation result can be obtained by combining the two-level index fuzzy comprehensive evaluation result of the static error.

[0052] (1) According to the fuzzy comprehensive evaluation method, combining the three-level index weight vector A 31 , for the dynamic error three-level index:

[0053] B 31 = A 31 · R 31

[0054] Similarly, there are

[0055] B 32 = A 32 · R 32

[0056] B 33 = A 33 · R 33

[0057] The obtained B 31 , B 32 , B 33 is further combined to obtain the secondary fuzzy comprehensive evaluation result B 22 , which is calculated as follows

[0058]

[0059] (2) For static error secondary indicators:

[0060] B 21 = A 21 · R 21

[0061] Combined with the weight vector A1 of the primary indicator, the comprehensive performance evaluation result is obtained as

[0062]

[0063] Further, the error compensation includes,

[0064] Accurate measurement and analysis of errors to determine specific error items that need to be compensated;

[0065] Develop a compensation plan based on measurement results, including selecting appropriate compensation methods and setting compensation parameters;

[0066] Implement the compensation strategy in the control system;

[0067] Verify the compensation effect by measuring and evaluating the performance of the machine tool again, and further adjust the compensation strategy according to the feedback.

[0068] The beneficial effects of the present application are:

[0069] In the present application, the spatial accuracy of high-speed high-precision gantry vertical machining center is analyzed in depth, the influencing factors are discussed, and an effective evaluation method is proposed. Combined with the establishment and analysis of the spatial error model, a systematic precision evaluation process is provided, and corresponding error compensation is carried out combined with the evaluation results, which provides theoretical basis and practical guidance for improving the precision stability and machining quality of the machining center. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 The evaluation and compensation method flowchart of the present application is shown in the figure;

[0071] Figure 2 The evaluation flowchart of the present application is shown in the figure;

[0072] Figure 3 The spatial accuracy evaluation system of the present application is shown in the figure;

[0073] Figure 4 The error compensation flowchart of the present application is shown in the figure. DETAILED DESCRIPTION

[0074] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0075] Machine tool spatial accuracy generally refers to the positioning accuracy of the spatial coordinates (X, Y, Z) of the numerical control machine tool within its machining space volume range.

[0076] Specifically, machine tool spatial accuracy is the result of the comprehensive action of multiple error elements, including but not limited to:

[0077] Linear displacement error: refers to the error of the machine tool when moving in a single axis.

[0078] Straightness error: describes the degree of deviation from the ideal straight line during the movement of the machine tool.

[0079] Perpendicularity error: refers to the deviation of the ideal perpendicular relationship between two or more axes from the actual perpendicular relationship.

[0080] Rolling error: deviation from the ideal position when the machine tool rotates around an axis.

[0081] Yaw error: swing error of the machine tool about an axis during movement.

[0082] Pitch error: Similar to yaw error, it is the error in oscillation around another axis.

[0083] The level of machine tool spatial accuracy directly affects the dimensional accuracy and shape accuracy of the machined parts. By classifying the above indicators, the spatial accuracy is roughly composed of the following parts:

[0084] (1) Positioning accuracy: This refers to the deviation between the actual position of the machine tool on the specified coordinate position and the target position. The higher the positioning accuracy, the smaller the dimensional error of the products machined by the machine tool.

[0085] (2) Repeatability: This refers to the consistency of the actual position when the machine tool reaches the same target position multiple times. A high-precision machine tool can achieve a repeatability of 0.1 μm or higher.

[0086] (3) Twenty-one error: These include the comprehensive reflection of geometric accuracy such as straightness, flatness, parallelism, equidistance, coincidence, perpendicularity, and rotation. These errors collectively determine the overall spatial accuracy of the machine tool.

[0087] Please refer to Figures 1-4 , the present application provides a method for evaluating and compensating the spatial accuracy of a gantry vertical machining center, which specifically comprises the following steps,

[0088] S1: Establish an error model in combination with the influencing factors of spatial accuracy;

[0089] In an embodiment, establishing the error model includes linearly superimposing errors of each motion pair in the same degree of freedom, simplifying and combining error elements of a three-axis precision CNC machine tool, as follows, as shown in the following table:

[0090] Table 1 Geometric error elements

[0091]

[0092]

[0093] Table 2 Thermal error elements

[0094]

[0095] Table 3 Force error elements

[0096]

[0097] In the actual situation, there are 3 movement (geometric) errors δ yX , δ xX , δ zX and 3 angle errors ε yX , ε xX , εzX , 1 item perpendicularity error S yX , 3 items thermal drift error δ xX (t), δ yX (t), δ zX (t) and 3 items force error δ xX (f), δ yX (f), δ zX (f), the error transformation matrix of the reference coordinate system to the X axis is:

[0098]

[0099] When the worktable moves a distance y along the Y axis, there are 3 items of movement (geometric) error δ yY , δ xY , δ zY , 3 items of rotation error ε yY , ε xY , ε zY , 3 items of thermal drift error δ xY (t), δ yY (t), δ zY (t) and 3 items of force error δ xY (f), δ yY (f), δ zY (f), according to the coordinate transformation and the small error assumption theory, the transformation matrix of the Y axis to the reference coordinate system is:

[0100]

[0101] When the worktable moves a distance z along the Z axis, there are 3 items of movement (geometric) error δ yZ , δ xZ , δ zZ , 3 items of rotation error ε yZ , ε xZ , ε zZ , 2 items of perpendicularity error S xz , S yz , 3 items of thermal drift error δ xZ (t), δ yZ (t), δ zZ (t) and 3 items of force error δ xZ (f), δ yZ (f), δ zZ (f), therefore, the error transformation matrix of the reference coordinate system to the Z axis is:

[0102]

[0103] When the machine tool moves a distance x, y, z along the X axis, Y axis, Z axis respectively, the transformation matrix is

[0104]

[0105] S2: constructing a spatial accuracy evaluation system;

[0106] In an embodiment, the evaluation system comprises fuzzy comprehensive evaluation, and the fuzzy comprehensive evaluation comprises,

[0107] S21: establishing an evaluation index system according to an evaluation target, and extracting an evaluation index set;

[0108] The process of establishing the evaluation index system comprises gradually decomposing the evaluation target into sub-targets at different levels according to a total target, a criterion layer, and an index layer, obtaining an evaluation index system with a progressive structure, and collectively referring to the sub-targets at different levels as evaluation indexes. The evaluation indexes describe different aspects of the object to be evaluated, and characterize the features of the object to be evaluated.

[0109] S22: determining index weights;

[0110] In the process of primary fuzzy comprehensive evaluation, a fuzzy relationship between a factor set U and an evaluation set V is established In a limited domain, which can be represented by a matrix R, r ij = μ R (u i ,v j ), 0 ≤ r ij ≤ 1, representing the membership degree of a certain research object evaluated as v i from the factor u j . A weight vector W is determined, Y = WR is obtained, and the result is evaluated according to the value of Y.

[0111] S23: constructing an index membership function and a comprehensive evaluation mathematical model.

[0112] The process comprises establishing a multi-level evaluation model, which comprises firstly performing primary comprehensive evaluation within each layer, and then performing comprehensive evaluation of the evaluation results of each layer at a higher level. The steps of multi-level fuzzy comprehensive evaluation are as follows:

[0113] (1) dividing factors X = {x1, x2,..., x n} into s subsets according to attributes,

[0114]

[0115] (2) making comprehensive decisions on the sub-factors X i , and setting y = {y1, y2,..., y m} as an evaluation set, and the weight distribution of each factor in X i

[0116]

[0117] wherein​

[0118]

[0119] If R i is a single factor matrix, then the first level evaluation vector is

[0120]

[0121] (3) Each X i is regarded as a factor, and X

[0122] X = {X1, X2,..., X s}

[0123] The single factor decision matrix of X is

[0124]

[0125] Each X i is given a weight distribution according to importance as part of X:

[0126] A = (a1, a2,..., a s )

[0127] Thus, B = A·R = (b1, b2,..., b m )

[0128] Thus, the second level fuzzy comprehensive evaluation model block diagram is obtained.

[0129] Thus, the second level fuzzy comprehensive evaluation model block diagram is obtained.

[0130] The first factor set X i is further subdivided, and thus the third level fuzzy comprehensive evaluation model, the fourth level fuzzy comprehensive evaluation model, and so on are obtained.

[0131] In an embodiment, referring to Figure 3 , the evaluation system includes 3 levels, the first level is the overall target, i.e., the numerical control machine tool overall precision factor set U = {U1, U2}; the second level is the second level target factor set U i (i = 1, 2), wherein U1 is a static error factor set, and U2 is a dynamic error factor set, U1 = {J 11 ,J 12 ,J 13 ,J 14 ,J 15 ,J 16}, U2 = {U 21 ,U 22 ,U 23}, and the third level is the third level target factor set U 2i (i = 1, 2, 3), wherein,

[0132] U21 = {D 11 = {D 12 = {D 13 = {D 14 = {D 15 = {D 16}

[0133] U 22 = {D 21 = {D 22 = {D 23 = {D 24 = {D 25 = {D 26}

[0134] U 23 = {D 31 = {D 32 = {D 33 = {D 34 = {D 35 = {D 36}.

[0135] S3: Give the evaluation method of machine tool space accuracy combined with the evaluation system;

[0136] From the weight proportion of each weight index, further get each weight vector, get the weight vector

[0137] A1, A 21 , A 22 , A 31 , A 32 , A 33 . The weight ratio shown in the following table is given for reference.

[0138]

[0139]

[0140]

[0141]

[0142] From the above table, each weight vector can be obtained:

[0143] A1 = (0.4, 0.6)

[0144] A 21 = (0.125, 0.125, 0.3, 0.15, 0.15, 0.15)

[0145] A 22 = (0.33, 0.33, 0.33)

[0146] A 31 = A32 = A 33 = (0.12, 0.18, 0.18, 0.15, 0.21, 0.15)

[0147] Next step to establish single factor fuzzy evaluation matrix, first give the evaluation set, evaluation set is the industry to each level of evaluation index given comment set, for different evaluation index, its comment level represents the meaning of each different. Imported into the computer, according to the characteristics of each performance index of numerical control machine tool, give evaluation set V = {v i}, a total of 6 evaluation levels, namely V = {v1, v2, v3, v4, v5, v6}, in which v1 = {excellent}, v2 = {better}, v3 = {good}, v4 = {better}, v5 = {general}, v6 = {worse}, that is, the evaluation set is V = {excellent, better, good, better, general, worse}, the positioning accuracy of machine tool can be divided into six intervals according to different standards, for the machine tool with bidirectional stroke range of 800-1250mm, reference as follows:

[0148] excellent: the standard deviation of positioning accuracy is within ±2μm; better: the standard deviation of positioning accuracy is between ±2μm and ±4μm; good: the standard deviation of positioning accuracy is between ±4μm and ±6μm; better: the standard deviation of positioning accuracy is between ±6μm and ±8μm; general: the standard deviation of positioning accuracy is between ±8μm and ±10μm; worse: the standard deviation of positioning accuracy exceeds ±10μm.

[0149] Through multiple measurements of each accuracy index, the measurement results are analyzed, and the percentage classification is carried out according to the accuracy interval, to obtain the judgment statistical table, hereinafter the judgment statistical table of dynamic error three level index is listed for reference, as shown in the following table.

[0150]

[0151] In the table represents the proportion of the accuracy evaluation result for this index, and satisfies

[0152]

[0153] According to the evaluation system, the corresponding single factor fuzzy comprehensive evaluation matrix is obtained

[0154]

[0155] The obtained results are substituted into the evaluation matrix to obtain the two level fuzzy evaluation matrix R 21 and three level fuzzy evaluation matrix R 31 , R 32 , R 33The fuzzy comprehensive evaluation result of the second level index can be obtained from the dynamic error third level index weight vector, and then the overall comprehensive evaluation result can be obtained by combining the fuzzy comprehensive evaluation result of the second level index of the static error.

[0156] (1) The fuzzy comprehensive evaluation method is combined with the third level index weight vector A 31 For the dynamic error third level index, we have:

[0157] B 31 =A 31 ·R 31

[0158] Similarly, we have

[0159] B 32 =A 32 ·R 32

[0160] B 33 =A 33 ·R 33

[0161] The obtained B 31 , B 32 , and B 33 are further combined to obtain the second level fuzzy comprehensive evaluation result B 22 , which is calculated as follows

[0162]

[0163] (2) For the static error second level index, we have:

[0164] B 21 =A 21 ·R 21

[0165] Combined with the weight vector A1 of the first level index, the comprehensive performance evaluation result is obtained as

[0166]

[0167] S4: Analyze the error compensation based on the evaluation result to improve the spatial accuracy evaluation method.

[0168] In an embodiment, the error compensation includes,

[0169] Accurate measurement and analysis of errors to determine specific error items that need to be compensated;

[0170] Developing a compensation plan based on the measurement results, including selecting appropriate compensation methods and setting compensation parameters;

[0171] Implementing the compensation strategy in the control system;

[0172] The compensation effect is verified by re-measuring and evaluating the performance of the machine tool, and the compensation strategy is further adjusted according to the feedback.

[0173] The compensation effect verification is a key process to ensure the effectiveness of the compensation strategy. The verification method usually includes re-performing precision detection and comparing with the detection results before compensation. In addition, standard parts can be used for machining test to intuitively evaluate the machining precision after compensation. The data collected in the verification process will be used to analyze the performance of the compensation strategy, including the improvement degree of precision before and after compensation, stability and any potential new problems. Through these methods, it can be ensured that the error compensation strategy achieves the expected effect, and provides the basis for future optimization.

[0174] The compensation strategy includes a feedback interruption strategy and an origin translation strategy;

[0175] Specifically, the working principle of the feedback interruption strategy is that the computer calculates the spatial error according to the error synthesis model, converts it into a pulse signal, and performs addition and subtraction operation with the encoder feedback signal. The operation result is inserted into the servo system feedback loop in the form of a phase signal, and the machine tool control system drives the machine tool to implement the next movement based on the phase signal.

[0176] Specifically, the working principle of the origin translation strategy is that the computer calculates the position error value of the machine tool, converts the value into a compensation signal, and sends it to the CNC system through the I / O port. The compensation signal is sent to the control signal of the machine tool servo loop through the origin offset function of the external coordinate system of the CNC system to achieve the compensation purpose. This strategy does not need to change the software and hardware of the CNC system and instructions, and only needs to add data interaction program code on the PLC.

[0177] The present application deeply analyzes the spatial precision of high-speed and high-precision gantry vertical machining center, discusses its influencing factors, and proposes an effective evaluation method. Combined with the establishment and analysis of the spatial error model, a systematic precision evaluation process is provided, and corresponding error compensation is carried out combined with the evaluation results, which provides a theoretical basis and practical guidance for improving the precision stability and machining quality of the machining center.

[0178] It should be understood that the above is only an example, and does not constitute any limitation on the technical solutions of the present application. In specific applications, those skilled in the art can set it up according to the needs, and the present application does not limit it.

[0179] It should be noted that the above-described workflow is only illustrative and does not limit the scope of protection of the present application. In actual application, those skilled in the art can select part or all of them to achieve the purpose of the present embodiment, and this place does not limit it.

[0180] In addition, technical details not described in detail in the present embodiment can be found in the evaluation method provided by any embodiment of the present application, which will not be described here.

[0181] Furthermore, it is to be understood that the terms "including", "comprising", "consisting of", or variations thereof herein are intended to be broad and encompass the terms "consisting essentially of" and "consisting of". It is not intended that any of the foregoing terms be limited to the inclusion of only an amount of zero.

[0182] The above-mentioned serial numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0183] From the above description of the embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be realized by means of software and the necessary general hardware platform, of course, they can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk), and includes a number of instructions for making a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) execute the methods described in the embodiments of the present application.

[0184] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent flow transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for evaluating and compensating the spatial accuracy of a gantry vertical machining center, characterized in that: Specifically comprising the following steps, An error model is established in combination with the influencing factors of spatial accuracy; An evaluation system of spatial accuracy is constructed; An evaluation method of machine tool spatial accuracy is given in combination with the evaluation system; The error compensation is analyzed according to the evaluation results, and the spatial accuracy evaluation method is improved; The evaluation system includes fuzzy comprehensive evaluation, and the fuzzy comprehensive evaluation includes, According to the evaluation target, an evaluation index system is established, and an evaluation index set is extracted; The index weight is determined; The index membership function and the comprehensive evaluation mathematical model are constructed; The evaluation system comprises three levels, the first level is a total target, i.e. a whole precision factor set of the numerical control machine tool ; the second level is a second level target factor set , wherein is a static error factor set, is a dynamic error factor set, , the third level is a third level target factor set , wherein, ； The evaluation method comprises obtaining a corresponding single-factor fuzzy comprehensive evaluation matrix according to the evaluation system The obtained result is substituted into the evaluation matrix to obtain a secondary fuzzy evaluation matrix and a tertiary fuzzy evaluation matrix The secondary index fuzzy comprehensive evaluation result can be obtained from the dynamic error tertiary index weight vector, and the overall comprehensive evaluation result can be obtained by combining the secondary index fuzzy comprehensive evaluation result of the static error. (1) The fuzzy comprehensive evaluation method is combined with the weight vector of the three-level index For the dynamic error three-level index, there are: Similarly, The obtained Further combining the obtained secondary fuzzy comprehensive evaluation results The calculation is as follows (2) For the secondary index of static error: combining the weight vector of the primary index and thus the comprehensive performance evaluation result is 。 2. The method for evaluating and compensating the spatial accuracy of a gantry type vertical machining center according to claim 1, characterized in that: The error model is established, the errors of each degree of freedom of the kinematic pair are linearly superimposed, the error elements of the three-axis precision CNC machine tool are simplified and combined, and the specific steps are as follows, There are 3 movement errors when the worktable X-axis moves a distance x , , , 3 rotation errors , 1 perpendicularity error , 3 thermal drift errors and 3 force errors , so the error transformation matrix of the reference coordinate system to the X-axis is: Worktable Y axis moving distance There are 3 moving errors , , 3 rotation errors 3 thermal drift errors and 3 force errors According to the coordinate transformation and the small error assumption theory, the transformation matrix of the Y axis to the reference coordinate system is: There are 3 movement errors when the worktable Z axis moves a distance z , , , 3 rotation errors , 2 perpendicularity errors , , 3 thermal drift errors and 3 force errors , so the error transformation matrix of the reference coordinate system to the Z axis is: When the machine tool moves along the X-axis, Y-axis, and Z-axis directions respectively , , The transformation matrix is .

3. The method for evaluating and compensating the spatial accuracy of a gantry type vertical machining center according to claim 1, characterized in that: The process of establishing the evaluation index system includes gradually decomposing the evaluation target into sub-targets at each level according to the total target, the criterion layer and the index layer, obtaining an evaluation index system with a progressive structure, and the sub-targets at each level are collectively referred to as evaluation indexes. The evaluation indexes describe different aspects of the object being evaluated and characterize the features of the object being evaluated.

4. The method for evaluating and compensating the spatial accuracy of a gantry type vertical machining center according to claim 1, characterized in that: The evaluation system also includes establishing a fuzzy relationship between the factor set U and the evaluation set V in the initial fuzzy comprehensive evaluation process. In a finite domain, It can be represented by matrix R. , indicating from factors A certain research subject was rated as The degree of membership is determined, the weight vector W is determined, and Y = WR is obtained. The results are evaluated based on the Y value.

5. The method for evaluating and compensating the spatial accuracy of a gantry type vertical machining center according to claim 4, characterized in that: The evaluation system also includes establishing a multi-level evaluation model, which includes first performing primary comprehensive evaluation within each layer, and then performing high-level comprehensive evaluation between layers on the evaluation results of each layer; The steps of multi-level fuzzy comprehensive evaluation are as follows: (1) the factor into s subsets by attribute, (2) Sub-factors Make a comprehensive decision, respectively, For the evaluation set, The weight distribution of each factor in Wherein If For single factor matrix, the first level evaluation vector is (3) each of the considered as a factor, record The single-factor decision matrix of X is Each As part of X, give a weight assignment by importance: Thus The secondary fuzzy comprehensive evaluation model block diagram is obtained; The first level factor set Subdivision, so get three fuzzy comprehensive evaluation model, four fuzzy comprehensive evaluation model, and so on.

6. The method for evaluating and compensating the spatial accuracy of a gantry type vertical machining center according to claim 1, characterized in that: The error compensation includes, Accurate measurement and analysis of errors to determine the specific error items that need to be compensated; According to the measurement results, a compensation plan is developed, including selecting appropriate compensation methods and setting compensation parameters; Implement the compensation strategy in the control system; Verify the compensation effect by measuring and evaluating the performance of the machine tool again, and further adjust the compensation strategy according to the feedback.

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