Detection method and detection system for blade machining process of five-axis numerical control machine tool

Abstract

The invention relates to the field of machine tool control, in particular to a detection method and system for the blade machining process of a five-axis numerical control machine tool, and the detection method comprises the steps: carrying out the three-dimensional scanning of a finished blade to obtain a sample model, obtaining a simulation tool path according to the sample model, and obtaining a simulation tool path according to the deviation between a standard tool path and the simulation tool path; and obtaining a five-axis deviation value. And obtaining a detection result of the five-axis numerical control machine tool according to the five-axis deviation value. The detection system comprises a three-dimensional scanner, a programming module, a calculation module, a detection result output module and a data storage module. Compared with empirical judgment in the blade machining process, the method is more reliable, and is more efficient than other measurement methods. Meanwhile, the corresponding relation between the deviation axis and the deviation reason is established, the time for technicians to analyze the problem reason is saved, guidance is provided for debugging and correction in the blade machining process, and the blade machining precision can be effectively improved.

Description

Technical Field

[0001] The present application relates to the field of machine tool control, and in particular to a detection method and a detection system for a blade machining process of a five-axis CNC machine tool. Background Art

[0002] The profile of a steam turbine blade can be regarded as a smooth and complex spatial distortion surface formed by a set of unequally spaced or equidistant parallel cross-sectional profiles, which has good wave characteristics and strength. Due to the complex shape of steam turbine blades, it is very difficult to process. In industrial production, five-axis CNC machine tools are often used to use spiral milling to ensure the accuracy of the finished product.

[0003] However, in the current production process of steam turbine blades, the following problem arises: due to the special shape of steam turbine blades, it is difficult to measure them using conventional measurement methods, and thus it is impossible to detect and analyze the blade processing process. Summary of the invention

[0004] The technical problem to be solved by the present application is that the blade processing process of the existing five-axis CNC machine tools is difficult to detect.

[0005] The present application provides a detection method and detection system for a blade processing process of a five-axis CNC machine tool. The five-axis CNC machine tool uses a processing tool to process the blade. The processing tool moves on five processing axes. The five processing axes include: an X-axis, a Y-axis, a Z-axis, an A-axis and a B-axis. The X-axis and the Y-axis are the movement axes of the processing tool of the five-axis CNC machine tool in the horizontal direction. The Z-axis is the axis of the fixture of the five-axis CNC machine tool that reciprocates in the vertical direction. The A-axis is the rotation axis of the fixture of the five-axis CNC machine tool, and the A-axis is perpendicular to the Z-axis and parallel to the X-axis. The B-axis is the swing axis of the tool head of the processing tool. The movement of the fixture on the Z-axis and the A-axis can be equivalent to the movement of the processing tool on the Z-axis and the A-axis.

[0006] The blade processing includes: Obtaining a standard model of the blade; Matching standard machining parameters and standard tool information to the standard model to obtain a standard tool path, wherein the standard tool path is a set of standard tool coordinates; The five-axis CNC machine tool controls the machining tool to move according to the standard tool path to process the blade to be machined into a finished blade.

[0007] In the first aspect, the detection method provided by the present application comprises the following steps: Performing three-dimensional scanning on the finished blade to obtain a sample model; Matching the standard machining parameters and the standard tool information to the sample model to obtain a simulated tool path, wherein the simulated tool path is a set of simulated tool coordinates; Calculating the deviation of the simulated tool coordinates in the simulated tool path according to the set of standard tool coordinates to obtain a five-axis deviation; Obtaining a detection result of the five-axis CNC machine tool according to the five-axis deviation, wherein the detection result includes a deviation axis and a deviation cause; The deviation axis is a combination of any number of axes among the five machining axes, and the deviation cause is a combination of deviation causes corresponding to the deviation axis; When the deviation axis is the X-axis, the deviation cause includes X-axis origin offset. When the X-axis origin offset occurs, the blade root and tail band of the finished blade have dimensional deviations, which are caused by tool wear or machine tool vibration. When the deviation axis is the Y axis, the deviation causes include the Y axis zero offset and the Y axis origin offset. When the Y axis zero offset and the Y axis origin offset occur, the finished blade has a profile contour line that is offset at the processing start or end, and the air inlet and air outlet edges are too thick or too thin, which is caused by configuration problems of processing parameters such as tool, feed rate, cutting depth and spindle speed, or device structures such as installation problems of guide rails, sliders and screw rods. When the deviation axis is the Z axis, the deviation causes include the Z axis zero point offset, the Z axis origin offset and the Z axis sub-axis positive generatrix deviation. When the Z axis zero point offset, the Z axis origin offset and the Z axis sub-axis positive generatrix deviation occur, the angle of the blade assembly surface deviates or the blade profile gradually becomes thinner from one end to the other end, which is caused by the two sub-axes of the Z axis of the five-axis CNC machine tool not being in the same plane; When the deviation is for the A-axis, the deviation cause includes a generatrix deviation on the A-axis side. When a generatrix deviation on the A-axis side occurs, the surface quality of the blade is locally abnormal, which is caused by the inconsistency of the two sub-axes of the A-axis of the five-axis CNC machine tool; When the deviation is for the B axis, the cause of the deviation includes B axis zero point offset. When B axis zero point offset occurs, tool connection marks appear on the smooth surface of the blade, which is caused by a deviation between the B axis zero point and the Z axis of the five-axis CNC machine tool.

[0008] When the deviation axis is a combination of multiple axes, the deviation causes corresponding to each axis should be combined and analyzed to obtain the final deviation cause.

[0009] Specifically, the step of performing three-dimensional scanning on the finished blade to obtain a sample model includes: Evenly spraying positioning powder on the finished blades; The point cloud data of the positioning powder is obtained by using a three-dimensional scanner. The three-dimensional scanner uses the principle of quasi-triangulation to scan the positioning powder from multiple angles and puts the point cloud data in the same quasi-triangulation model.

[0010] The sample model is obtained according to the point cloud data.

[0011] Specifically, the standard machining parameters include: fixture model, blank size, machining origin, rough machining program and finishing program; the standard tool information includes: tool model, tool length and tool head diameter Specifically, the performing deviation calculation for each simulated tool coordinate in the simulated tool path includes: For each simulated tool coordinate in the simulated tool path N j ( x 2 , y 2 , z 2 , a 2 , b 2 ), calculate the standard tool path i = j Standard tool coordinates N i ( x 1 , y 1 , z 1 , a 1 , b 1 ) and the simulated tool coordinates N j ( x 2 , y 2 , z 2 , a 2 , b 2 ) to obtain the five-axis deviation; in, i represents the serial number of the tool path coordinates, i ∈{1,2,3,...}, x 1 , y 1 , z 1 ,a 1 and b 1 represents the five components of the standard tool coordinates on the machining axis, j represents the serial number of the simulated tool coordinates, j ∈{1,2,3,...}, x 2 , y 2 , z 2 , a 2 and b 2 represents the five components of the simulated tool coordinates on the machining axis, the number of the simulated tool coordinates is equal to that of the standard tool coordinates, and the five-axis deviation includes X 偏 , Y 偏 , Z 偏 , A 偏 , B 偏 , .

[0012] Specifically, the step of obtaining the detection result of the five-axis CNC machine tool according to the five-axis deviation comprises: For all X 偏 , Y 偏 , Z 偏 , A 偏 , B 偏 The absolute value sums are calculated respectively, and the absolute value sums are compared with a set determination threshold to obtain the deviation axis.

[0013] In the second aspect, the detection system provided by the present application includes the following modules: 3D scanner, programming module, calculation module, detection result output module and data storage module; The three-dimensional scanner is used to perform three-dimensional scanning on the finished blade to obtain a sample model, and the sample model is stored in the data storage module; The programming module is used to obtain standard processing parameters and standard processing parameters of the standard model from the data storage module, and match the standard processing parameters and the standard tool information to the sample model to obtain a simulated tool path; The calculation module is used to obtain the simulated tool path, and perform deviation calculation between the simulated tool path and the standard tool path in the data storage module to obtain a five-axis deviation; The detection result output module is used to output the detection result of the five-axis CNC machine tool according to the five-axis deviation.

[0014] Specifically, the three-dimensional scanner includes a scanning lens, positioning powder and a sample fixing platform. The finished blade is fixed on the sample fixing platform. The finished blade is evenly covered with the positioning powder. The scanning lens faces the sample fixing platform and can rotate around the sample fixing platform.

[0015] Specifically, the three-dimensional scanner also includes a visual receiving module, which is connected to the scanning lens, receives point cloud data of the positioning powder acquired by the scanning lens, and establishes the sample model according to the point cloud data.

[0016] Specifically, the programming module obtains the fixture model, blank size, machining origin, rough machining program, fine machining program, tool model, tool length and tool head diameter of the sample model from the data storage module.

[0017] Specifically, the monitoring system further includes a machine tool control module, which obtains the detection result output by the detection result output module and issues a control instruction to the five-axis CNC machine tool according to the detection result.

[0018] This application has the following technical effects: The present invention overcomes the problem in the prior art that the finished blades are difficult to measure and rely on the experience analysis of technicians to determine the cause of the deviation problem in the blade processing process. A more accurate, easy to implement and efficient method is proposed to detect the blade processing process and locate the cause of the problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easily understood. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-restrictive manner, and the same or corresponding numbers represent the same or corresponding parts.

[0020] Figure 1 is a flow chart of a detection method for a blade processing process according to an embodiment of the present application; Figure 2 This is a display diagram of the finished blade in the embodiment of the present application; Figure 3 is a schematic diagram of a simulated tool path in an embodiment of the present application; Figure 4 It is a schematic diagram of the detection system of the blade processing process in the embodiment of the present application. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0022] It should be understood that when the terms "first", "second", etc. are used in the claims, specification and drawings of the present application, they are only used to distinguish different objects, rather than to describe a specific order. The terms "include" and "comprise" used in the specification and claims of the present application indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0023] During the production process of turbine blades, the inventors of the present application found that due to the special and complex shape of the blades, it is difficult to detect the processing accuracy of the finished blades through some conventional measurement methods. Even if it is detected that the processing accuracy of the finished blades is abnormal, the technicians have no way of knowing what caused the abnormal processing accuracy during the blade processing. It often takes a lot of experiments and analysis to debug and correct the blade processing process.

[0024] In view of this problem, the inventors in this field have studied how to detect the blade processing process and if the cause of the problem is known, and proposed a detection method and detection system for the blade processing process of a five-axis CNC machine tool: First, in this embodiment, if Figure 1 As shown, the detection method of the blade processing process includes the following steps: S1: Perform three-dimensional scanning on the finished blade to obtain a sample model. In this embodiment, the processed blade is Figure 2 The blade is evenly sprayed with positioning powder so that it completely covers the blade, and then put into a 3D scanner. The 3D scanner scans and obtains the point cloud data of the positioning powder. After adjusting the angle and repeating the scan multiple times, the complete point cloud data of the blade is obtained, and a sample model in prt format is generated based on these point cloud data.

[0025] S2: Match the standard processing parameters and standard tool information to the sample model to obtain the simulated tool path. Open Geomagic Design X software to reverse engineer the sample model, use RCS software to program it, define the fixture model, blank size, processing origin, roughing program, finishing program, tool model, tool length and tool head diameter. These parameter values ​​are consistent with the parameter values ​​defined in the processing of the finished blade. Then, the simulated tool path can be generated in the software according to the cross section of the sample model. Figure 3 As shown, the simulated tool path contains simulated tool coordinates one by one. This embodiment adopts incremental programming, that is, each simulated tool coordinate is generated based on the previous simulated tool coordinate.

[0026] S3: Calculate the deviation of the simulated tool coordinates in the simulated tool path according to the set of standard tool coordinates to obtain the five-axis deviation. Table 1 shows some simulated tool coordinates and standard tool coordinates in this embodiment: Table 1 Coordinates of simulated tool paths and standard tool paths For each simulated tool coordinate in the simulated tool path N j ( x 2 , y 2 , z 2 , a 2 , b 2 ), calculate the standard tool path i = j Standard tool coordinates N i ( x 1 , y 1 , z 1 , a 1 , b 1 ) and simulated tool coordinates N j ( x 2 , y 2 , z 2 , a 2 , b 2 ) to obtain the five-axis deviation; in, i Indicates the serial number of the tool path coordinates, i ∈{1,2,3,...}, x 1 , y 1 , z 1 , a 1 and b 1 Represents the five components of the standard tool coordinates on the machining axis, j Indicates the serial number of the simulated tool coordinates, j ∈{1,2,3,...}, x 2 , y 2 , z 2 , a 2 and b 2 It represents the five components of the simulated tool coordinates on the machining axis. The number of simulated tool coordinates is equal to that of standard tool coordinates. The five-axis deviation includes X 偏 , Y 偏 , Z 偏 , A 偏 , B 偏 , .

[0027] The results are shown in Table 2: Table 2 Five-axis deviation scale S4: obtaining a detection result of the five-axis CNC machine tool according to the five-axis deviation, the detection result including the deviation axis and the deviation cause; The deviation axis is a combination of any number of axes among the five machining axes, and the deviation cause is a combination of the deviation causes corresponding to the deviation axis; When the deviation axis is the X-axis, the deviation causes include the X-axis origin offset. When the X-axis origin offset occurs, the blade root and tail band of the finished blade will have dimensional deviations, which is caused by tool wear or machine vibration; When the deviation axis is the Y axis, the deviation causes include the Y axis zero offset and the Y axis origin offset. When the Y axis zero offset and the Y axis origin offset occur, the finished blade surface contour line will be offset at the start or end of the processing, and the air inlet and outlet edges will be too thick or too thin. This is caused by the configuration of processing parameters such as tool, feed rate, cutting depth and spindle speed, or the installation of device structures such as guide rails, sliders and screw rods. When the deviation axis is the Z axis, the deviation causes include the Z axis zero offset, the Z axis origin offset and the Z axis sub-axis positive generatrix deviation. When the Z axis zero offset, the Z axis origin offset and the Z axis sub-axis positive generatrix deviation occur, the angle of the blade assembly surface deviates or the blade profile gradually becomes thinner from one end to the other end. This is caused by the two sub-axes of the Z axis of the five-axis CNC machine tool not being in the same plane. When the deviation is A-axis, the deviation causes include A-axis side generatrix deviation. When A-axis side generatrix deviation occurs, the surface quality of the blade is partially abnormal, which is caused by the inconsistency of the two sub-axes of the A-axis of the five-axis CNC machine tool. When the deviation is for the B-axis, the causes of the deviation include the B-axis zero point offset. When the B-axis zero point offset occurs, traces of tool connection appear on the smooth surface of the blade, which is caused by the deviation between the B-axis zero point and the Z-axis axis of the five-axis CNC machine tool.

[0028] According to the five-axis deviation data shown in Table 2, it can be obtained that the deviation axes are the X-axis and the Z-axis. Combined with the deviation reasons of the X-axis and the Z-axis, the technicians can further conclude that the center point of the machining tool has changed, that is, there is an RTCP accuracy problem, and then they can make a quick decision to correct the center point of the machining tool. To correct the center point of the machining tool, the correction iron block with the pressure gauge can be placed in the fixture of the five-axis CNC machine tool, the swing angle of the machining tool is set to 30° and -30°, and the two pressure gauge values ​​are measured. After adding the pressure gauge value to the Z-axis coordinate value, the offset value calculation formula can be entered to obtain the offset value of the Z-axis and the X-axis. The offset value calculation formula is: Among them, f is the Z-axis offset value, g is the X-axis offset value, and the remaining parameters are shown in Table 3: Table 3 Calculation parameters Therefore, the Z-axis offset value, that is, the distance between the spindle end face and the rotation center point, is f=100.1269, and the X-axis offset value, that is, the distance between the spindle axis and the rotation center point, is g=-0.0180.

[0029] Second, as Figure 4 As shown, the detection system provided in this embodiment includes the following modules: 3D scanner, programming module, calculation module, detection result output module and data storage module; The three-dimensional scanner is used to perform three-dimensional scanning on the finished blade to obtain a sample model, and the sample model is stored in the data storage module; The programming module is used to obtain the standard machining parameters and standard machining parameters of the standard model from the data storage module, and match the standard machining parameters and standard tool information to the sample model to obtain a simulated tool path; The calculation module is used to obtain the simulated tool path, and calculate the deviation between the simulated tool path and the standard tool path in the data storage module to obtain the five-axis deviation; The detection result output module is used to output the detection result of the five-axis CNC machine tool according to the five-axis deviation.

[0030] Specifically, the three-dimensional scanner includes a scanning lens, positioning powder and a sample fixing platform. The finished blade is fixed on the sample fixing platform. The finished blade is evenly covered with positioning powder. The scanning lens faces the sample fixing platform and can rotate around the sample fixing platform.

[0031] Specifically, the three-dimensional scanner also includes a visual receiving module, which is connected to the scanning lens, receives point cloud data of the positioning powder acquired by the scanning lens, and establishes a sample model according to the point cloud data.

[0032] Specifically, the programming module obtains the fixture model, blank size, machining origin, rough machining program, fine machining program, tool model, tool length and tool head diameter of the sample model from the data storage module.

[0033] Specifically, the monitoring system also includes a machine tool control module, which obtains the detection results output by the detection result output module and issues control instructions to the five-axis CNC machine tool according to the detection results.

[0034] Although this specification has shown and described a plurality of embodiments of the present application, it is obvious to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art will think of many changes, modifications and alternatives without departing from the thought and spirit of the present application. It should be understood that in the process of practicing the present application, various alternatives to the embodiments of the present application described herein may be adopted.

[0035] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for detecting a blade machining process of a five-axis CNC machine tool, wherein the five-axis CNC machine tool uses a machining tool to machine the blade, and the machining tool moves on five machining axes, and the five machining axes include: X-axis, Y-axis, Z-axis, A-axis and B-axis; The blade processing process includes: Obtaining a standard model of the blade; Matching standard machining parameters and standard tool information to the standard model to obtain a standard tool path, wherein the standard tool path is a set of standard tool coordinates; The five-axis CNC machine tool controls the machining tool to move according to the standard tool path to process the blade to be machined into a finished blade; Characterized in that the detection method comprises: Performing three-dimensional scanning on the finished blade to obtain a sample model; Matching the standard machining parameters and the standard tool information to the sample model to obtain a simulated tool path, wherein the simulated tool path is a set of simulated tool coordinates; Calculating the deviation of the simulated tool coordinates in the simulated tool path according to the set of standard tool coordinates to obtain a five-axis deviation; Obtaining a detection result of the five-axis CNC machine tool according to the five-axis deviation, wherein the detection result includes a deviation axis and a deviation cause; The deviation axis is a combination of any number of axes among the five machining axes, and the deviation cause is a combination of deviation causes corresponding to the deviation axis; When the deviation axis is the X axis, the deviation cause includes the X axis origin offset; When the deviation axis is the Y axis, the deviation causes include the Y axis zero point offset and the Y axis origin offset; When the deviation axis is the Z axis, the deviation causes include the Z axis zero point offset, the Z axis origin offset and the Z axis sub-axis positive generatrix deviation; When the deviation is for the A-axis, the deviation cause includes the A-axis side busbar deviation; When the deviation is of the B axis, the deviation cause includes the B axis zero point offset.

2. The detection method according to claim 1, characterized in that: The step of performing three-dimensional scanning on the finished blade to obtain a sample model comprises: Evenly spraying positioning powder on the finished blades; Using a three-dimensional scanner to obtain point cloud data of the positioning powder; The sample model is obtained according to the point cloud data.

3. The detection method according to claim 1, characterized in that: The standard processing parameters include: fixture model, blank size, processing origin, rough processing program and finishing program, and the standard tool information includes: tool model, tool length and tool head diameter.

4. The detection method according to claim 1, characterized in that: The performing deviation calculation for each simulated tool coordinate in the simulated tool path comprises: For each simulated tool coordinate in the simulated tool path N j ( x 2, y 2, z 2, a 2, b 2), calculate the standard tool path i = j Standard tool coordinates N i ( x 1, y 1, z 1, a 1, b 1) With the simulated tool coordinates N j ( x 2, y 2, z 2, a 2, b 2) The difference of the five components is used to obtain the five-axis deviation; in, i represents the serial number of the tool path coordinates, i ∈{1,2,3,...}, x 1. y 1. z 1. a 1 and b 1 represents the five components of the standard tool coordinates on the machining axis, j represents the serial number of the simulated tool coordinates, j ∈{1,2,3,...}, x 2. y 2. z 2. a 2 and b 2 represents the five components of the simulated tool coordinates on the machining axis. The number of the simulated tool coordinates is equal to that of the standard tool coordinates. The five-axis deviation includes X 偏 , Y 偏 , Z 偏 , A 偏 , B 偏 , 。 5. The detection method according to claim 4, characterized in that: The step of obtaining the detection result of the five-axis CNC machine tool according to the five-axis deviation comprises: For all X 偏 , Y 偏 , Z 偏 , A 偏 , B 偏 The absolute value sums are calculated respectively, and the absolute value sums are compared with a set determination threshold to obtain the deviation axis.

6. A detection system for blade machining process of a five-axis CNC machine tool, operated using the method according to any one of claims 1 to 5, characterized in that: It includes: a three-dimensional scanner, a programming module, a calculation module, a detection result output module and a data storage module; The three-dimensional scanner is used to perform three-dimensional scanning on the finished blade to obtain a sample model, and the sample model is stored in the data storage module; The programming module is used to obtain standard processing parameters and standard processing parameters of the standard model from the data storage module, and match the standard processing parameters and the standard tool information to the sample model to obtain a simulated tool path; The calculation module is used to obtain the simulated tool path, and perform deviation calculation between the simulated tool path and the standard tool path in the data storage module to obtain a five-axis deviation; The detection result output module is used to output the detection result of the five-axis CNC machine tool according to the five-axis deviation.

7. The detection system according to claim 6, characterized in that: The three-dimensional scanner includes a scanning lens, positioning powder and a sample fixing platform. The finished blade is fixed on the sample fixing platform. The finished blade is evenly covered with the positioning powder. The scanning lens faces the sample fixing platform and can rotate around the sample fixing platform.

8. The detection system according to claim 7, characterized in that: The three-dimensional scanner also includes a visual receiving module, which is connected to the scanning lens, receives point cloud data of the positioning powder acquired by the scanning lens, and establishes the sample model according to the point cloud data.

9. The detection system according to claim 6, characterized in that: The programming module obtains the fixture model, blank size, machining origin, rough machining program, fine machining program, tool model, tool length and tool head diameter of the sample model from the data storage module.

10. The detection system according to claim 6, characterized in that: The monitoring system further includes a machine tool control module, which obtains the detection result output by the detection result output module and issues a control instruction to the five-axis CNC machine tool according to the detection result.

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