Multi-point RTCP detection method for spatial precision degradation of large gantry five-axis machine tools

Abstract

The present invention discloses a multi-point RTCP detection method for spatial precision degradation of large gantry five-axis machine tools, comprising the following steps: S1, determining the timing detection time and the preset fixed position of the rotary analyzer ball head; assuming that the spatial precision of the machine tool is detected N times during the entire machining process, the complete machining cycle T is evenly divided to obtain the timing detection time T / N; according to the range of the machine tool workbench occupied by the workpiece and the predetermined machining path, the rotary analyzer ball head is evenly fixed in the non-machining area of ​​the workbench; S2, determining the RTCP detection trajectory; S3, detecting the ball head according to the machining path, judging whether the spatial precision meets the machining requirements, if so, no compensation is made, otherwise compensation is made, and then machining and detection are continued until the machining is completed. A multi-point RTCP detection method for spatial precision degradation of large gantry five-axis machine tools provided by the present invention comprises fixing the preset ball head at multiple points on the workbench, adding a wireless measuring probe to the machine tool tool magazine, stopping machining at regular intervals, and carrying out RTCP detection.

Description

Technical Field

[0001] The invention belongs to the technical field of RTCP detection of five-axis CNC machine tools, and in particular relates to a multi-point RTCP detection method for spatial precision degradation of large gantry five-axis machine tools. Background Art

[0002] The spatial accuracy of a five-axis machine tool refers to its ability to precisely control the tool's position and orientation relative to the workpiece in three-dimensional space. This is influenced by the machine's structure, drive system, control system, and tool system. During machining, thermal and mechanical deformation, component wear and aging, and vibration can degrade the tool's spatial accuracy. Therefore, continuous measurement is required to determine whether the spatial accuracy meets machining requirements.

[0003] The RTCP (Rotation Tool Center Point) function of five-axis machine tools is a programming technique commonly used in five-axis machining. This function changes the interpolation calculation process, allowing the tool center point to perform precise rotational motion around the workpiece. This allows programmers to use the tool center point as the programming reference point to set the tool path, without having to consider the tool's actual swing angle and the specific motion model of the machine tool. Based on this function, an RTCP detection method has been developed to detect the spatial accuracy of machine tools. This method uses a written detection driver to fix the position of the tool tip point, allowing the tool axis center to perform a predetermined five-axis linkage trajectory. An "8"-shaped RTCP detection trajectory is then used to detect the offset of the tool tip point using various detection equipment to achieve the measurement of the spatial error of the five-axis linkage.

[0004] Taking the AC double-swing head five-axis machine tool as an example, after turning on the RTCP function, the coordinate transformation relationship between the tool tip point and the tool axis point is:

[0005]

[0006] Where L is the distance from the tool tip to the tool axis, (X, Y, Z) is the coordinate of the tool tip, (X axis , Y axis , Z axis ) is the coordinate of the tool axis point.

[0007] The wireless rotation analyzer mainly consists of a ball head on the machine tool worktable and a wireless measuring probe inserted into the spindle. Users can customize the device to perform multi-axis testing. Its measurement principle is the same as that of the rotation detector. During measurement, the ball head representing the workpiece is used as a reference to measure the probe path representing the tool center point (TCP). In this way, the error in the cutting path can be directly measured and intuitively displayed in the x, y, and z dimensions. The ball head can be placed with the help of a magnetic base, and the probe can be placed in the tool chain for call-up and measurement operations when needed.

[0008] Existing measurement methods involve stopping the process at intervals and using non-cutting instruments to measure spatial errors. These methods require repeated disassembly and assembly of the testing equipment, making the measurement process cumbersome. Furthermore, the testing process suffers from low efficiency and high costs. Summary of the Invention

[0009] The purpose of the present invention is to solve the above problems and provide a multi-point RTCP detection method for spatial precision degradation of large gantry five-axis machine tools with high detection efficiency and convenient inspection.

[0010] To solve the above technical problems, the technical solution of the present invention is: a multi-point RTCP detection method for spatial precision degradation of large gantry five-axis machine tools, comprising the following steps:

[0011] S1. Determine the timing detection time and preset the fixed position of the rotating analyzer ball head;

[0012] Assuming that the machine tool spatial accuracy is tested N times during the entire machining process, the complete machining cycle T is evenly divided to obtain the timing detection time T / N; based on the machine tool worktable range occupied by the workpiece and the predetermined machining path, the rotating analyzer ball head is evenly fixed in the non-machining area of ​​the worktable;

[0013] S2, determine the RTCP detection trajectory;

[0014] S3. Detect the ball head according to the processing path to determine whether the spatial accuracy meets the processing requirements. If it does, no compensation is made; otherwise, compensation is made. Then, processing and detection are continued until the processing is completed.

[0015] Furthermore, the preset position of the ball head of the rotary analyzer in S1 needs to leave space for performing RTCP testing with the workpiece contour to avoid collision between the tool movement and the workpiece during testing.

[0016] Furthermore, the preset number of the rotating analyzer ball heads in S1 is N.

[0017] Furthermore, step S2 is specifically as follows: selecting a detection trajectory with good detection performance as the RTCP detection trajectory of all ball heads, the detection trajectory consists of a finite number of points, and a short stop is made at each point to ensure that the wireless rotation analyzer can collect stable error data.

[0018] Furthermore, the detection trajectory in step S2 is an "8"-shaped detection trajectory. The "8"-shaped detection trajectory is selected as the RTCP detection trajectory for all ball heads because the detection trajectory affects the accuracy of the detection error. The 8-shaped trajectory is composed of a limited number of points of the machine tool A-axis and C-axis angles, and a short pause is made at each point to ensure that the wireless rotation analyzer can collect stable error data. The 8-shaped trajectory function expression used is:

[0019]

[0020] Among them, ρ1, ρ2 are the swing amplitudes of A and C, ω is the frequency of the trigonometric function, is the initial phase of A and C. When selecting these values, avoid making A and C exceed the machine tool limit.

[0021] Furthermore, step S3 is specifically as follows: according to the processing path and the timed detection time plan, the processing is stopped at a fixed time, the tool is replaced with a wireless measuring probe in the tool magazine, and the tool tip is moved to the top of the corresponding ball head to carry out low-speed RTCP detection. At this time, it can be considered that the tool tip deviation is mainly caused by spatial error; the measurement result of the wireless rotation analyzer in the detection trajectory is the deviation Δx in the three directions of the machine tool coordinate system X, Y, and Z i , Δy i , Δz i (i=1,...,n), and the conversion relationship between the spatial error of each axis:

[0022]

[0023] where K x ,K y ,K z ,K A ,K C is the error coefficient matrix of each axis, R x ,R y ,R z ,R A ,R C is the error matrix composed of the error terms related to the 6 positions of each axis; for the detection trajectory of each ball head position, there are N point deviations (Δx i , Δy i , Δz i ). Define the comprehensive deviation of each point as:

[0024]

[0025] The spatial error of the ball head position is defined as:

[0026]

[0027] The spatial error threshold of the machining process is defined as ε r , ε r The size needs to be adjusted according to actual processing requirements.

[0028] Get spatial error After that, it is determined whether it meets the processing requirements; if not, compensation is required; then processing continues, and repeated inspections are carried out according to the predetermined inspection time plan until the entire processing cycle is completed.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention provides a multi-point RTCP detection method for the spatial precision degradation of large gantry five-axis machine tools. By using a wireless rotation analyzer to carry out RTCP detection, a preset ball head is fixed at multiple points on the workbench, a wireless measurement probe is added to the machine tool magazine, and processing is stopped at a fixed time to carry out RTCP detection. A multi-point RTCP detection method for the spatial precision degradation of large gantry five-axis machine tools is proposed.

[0031] 2. The present invention solves the problems of low detection efficiency and high detection cost in the prior art detection process.

[0032] 3. Compared with existing detection methods, the present invention only requires pre-setting the rotating analyzer ball head at multiple points before machining and adding a wireless probe to the tool magazine to achieve multi-point error detection throughout the entire machining cycle. This method eliminates the need to install the detection instrument before each test, greatly improving detection efficiency, simplifying the detection process, and reducing detection costs.

[0033] 4. The present invention effectively avoids the detection uncertainty that may be introduced due to repeated installation of the detection instrument, and further improves the accuracy and reliability of the detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a flow chart of a multi-point RTCP detection method for spatial precision degradation of a large gantry five-axis machine tool.

[0035] Figure 2 It is a structural schematic diagram of the rotary analyzer of the present invention;

[0036] Figure 3 It is a schematic diagram of the layout of the ball head of the multi-point fixed rotation analyzer in the non-processing area of ​​the workbench of the present invention;

[0037] Figure 4 This is a schematic diagram of the "8"-shaped detection trajectory adopted by the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0039] like Figures 1 to 4 As shown, the present invention provides a multi-point RTCP detection method for spatial precision degradation of a large gantry five-axis machine tool, comprising the following steps:

[0040] S1. Determine the timing detection time and preset the fixed position of the rotating analyzer ball head.

[0041] Assume that the machine tool's spatial accuracy is tested N times throughout the entire machining process. Divide the complete machining cycle T evenly to obtain the timed test time T / N. The preset number of rotating analyzer ball heads in S1 is N. Based on the machine tool worktable range occupied by the workpiece and the predetermined machining path, the rotating analyzer ball heads are evenly fixed in the non-machining area of ​​the worktable.

[0042] The structure of the rotating analyzer in S1 is as follows Figure 2 An example of a multi-point fixed rotating analyzer ball head layout is shown in Figure 3 As shown in the figure, the machine tool's spatial accuracy is determined by detecting the deviation between the actual position of the ball head and the RTCP programmed position. The preset position of the ball head needs to leave enough space between the workpiece contour and the RTCP test to avoid collision between the tool movement and the workpiece during the test.

[0043] S2. Determine the RTCP detection trajectory.

[0044] S2 is specifically as follows: a detection trajectory with good detection performance is selected as the RTCP detection trajectory of all ball heads. The detection trajectory consists of a finite number of points, and a short pause is made at each point to ensure that the wireless rotation analyzer can collect stable error data.

[0045] The detection trajectory in step S2 is an "8"-shaped detection trajectory, such as Figure 4 As shown in the figure, the "8"-shaped detection trajectory is selected as the RTCP detection trajectory for all ball heads because the detection trajectory affects the accuracy of the detection error. The 8-shaped trajectory consists of a limited number of points of the machine tool A-axis and C-axis angles, and a short pause is made at each point to ensure that the wireless rotation analyzer can collect stable error data. The 8-shaped trajectory function expression used is:

[0046]

[0047] Among them, ρ1, ρ2 are the swing amplitudes of A and C, ω is the frequency of the trigonometric function, is the initial phase of A and C. When selecting these values, avoid making A and C exceed the machine tool limit.

[0048] S3. Detect the ball head according to the processing path to determine whether the spatial accuracy meets the processing requirements. If it does, no compensation is made; otherwise, compensation is made. Then, processing and detection are continued until the processing is completed.

[0049] Step S3 is as follows: according to the machining path and the timed detection time plan, the machining is stopped at a fixed time, the tool is replaced with a wireless measuring probe in the tool magazine, and the tool tip is moved above the corresponding ball head to carry out low-speed RTCP detection. At this time, it can be considered that the tool tip deviation is mainly caused by spatial error; the measurement result of the wireless rotation analyzer in the detection trajectory is the deviation Δx in the three directions of the machine tool coordinate system X, Y, and Z. i , Δy i , Δz i (i=1,...,n), and the conversion relationship between the spatial error of each axis:

[0050]

[0051] where K x ,K y ,K z ,K A ,K C is the error coefficient matrix of each axis, R x ,R y ,R z ,R A ,R C is the error matrix composed of the error terms related to the 6 positions of each axis; for the detection trajectory of each ball head position, there are N point deviations (Δx i , Δy i , Δz i ). The comprehensive deviation of each point is defined as:

[0052]

[0053] The spatial error of the ball head position is defined as:

[0054]

[0055] The spatial error threshold of the machining process is defined as ε r , ε r The size needs to be adjusted according to actual processing requirements.

[0056] Get spatial error After that, with the threshold ε r Compare and determine whether it meets the processing requirements; if not, compensation is required; then continue processing and repeatedly test according to the predetermined inspection time plan until the entire processing cycle is completed.

[0057] The present invention addresses the problem of declining spatial accuracy in large gantry five-axis machine tools and low detection efficiency in the detection process of the prior art. The present invention fixes preset ball heads at multiple points on the workbench, adds wireless measuring probes to the machine tool magazine, stops processing at regular intervals and conducts detection to determine whether the spatial accuracy meets the processing requirements. This allows rapid detection without the need for repeated disassembly and assembly of detection equipment during the processing process, thus simplifying the detection process and improving detection efficiency. The present invention fixes preset ball heads at multiple points on non-processing paths before processing, eliminating the need for repeated disassembly and assembly during the processing process, thereby achieving rapid detection of spatial accuracy during the processing process. During the entire processing cycle, the efficiency of spatial accuracy detection can be improved by targeted selection of the number of preset ball heads and the spatial positions of the ball heads.

[0058] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A multi-point RTCP detection method for spatial precision degradation of large gantry five-axis machine tools, characterized by: The following steps are involved: S1. Determine the timing detection time and preset the fixed position of the rotating analyzer ball head; Assuming that the machine tool spatial accuracy is tested N times during the entire machining process, the complete machining cycle T is evenly divided to obtain the timing detection time T / N; based on the machine tool worktable range occupied by the workpiece and the predetermined machining path, the rotating analyzer ball head is evenly fixed in the non-machining area of ​​the worktable; S2, determine the RTCP detection trajectory; S3. Detect the ball head according to the processing path to determine whether the spatial accuracy meets the processing requirements. If it does, no compensation is made; otherwise, compensation is made. Then, processing and detection are continued until the processing is completed.

2. The multi-point RTCP detection method for spatial precision decay of a large gantry five-axis machine tool according to claim 1, characterized in that: The preset position of the rotary analyzer ball head in S1 needs to leave space for performing RTCP testing with the workpiece contour to avoid collision between the tool movement and the workpiece during detection.

3. The multi-point RTCP detection method for spatial precision decay of a large gantry five-axis machine tool according to claim 1, characterized in that: The preset number of the rotating analyzer ball heads in S1 is N.

4. The multi-point RTCP detection method for spatial precision decay of a large gantry five-axis machine tool according to claim 1, characterized in that: The step S2 specifically includes: selecting a detection trajectory with good detection performance as the RTCP detection trajectory of all ball heads, the detection trajectory consists of a finite number of points, and a short stop is made at each point to ensure that the wireless rotation analyzer can collect stable error data.

5. The multi-point RTCP detection method for spatial precision degradation of a large gantry five-axis machine tool according to claim 1, characterized in that: The detection trajectory in step S2 is an "8"-shaped detection trajectory. The "8"-shaped detection trajectory is selected as the RTCP detection trajectory for all ball heads because the detection trajectory affects the accuracy of the detection error. The "8" trajectory consists of the machine tool A-axis and C-axis angles at a limited number of points, and a brief pause is made at each point to ensure that the wireless rotation analyzer can collect stable error data.

6. The multi-point RTCP detection method for spatial precision degradation of a large gantry five-axis machine tool according to claim 1, characterized in that: The step S3 specifically includes: according to the processing path and the timed detection time plan, the processing is stopped at a fixed time, the tool is replaced with a wireless measuring probe in the tool magazine, and the tool tip is moved to the top of the corresponding ball head, and a low-speed RTCP detection is performed. At this time, it can be considered that the tool tip deviation is mainly caused by the spatial error; the measurement result of the wireless rotation analyzer in the detection trajectory is the deviation Δx in the three directions of the machine tool coordinate system X, Y, and Z. i , Δy i , Δz i (i=1,...,n), and the conversion relationship between the spatial error of each axis: where K x ,K y ,K z ,K A ,K C is the error coefficient matrix of each axis, R x ,R y ,R z ,R A ,R C is the error matrix composed of the error terms related to the 6 positions of each axis; for the detection trajectory of each ball head position, there are N point deviations (Δx i , Δy i , Δz i ); define the comprehensive deviation of each point as: The spatial error of the ball head position is defined as: The spatial error threshold of the machining process is defined as ε r , ε r The size needs to be adjusted according to actual processing requirements; Get spatial error After that, it is determined whether it meets the processing requirements; if not, compensation is required; then processing continues, and repeated inspections are carried out according to the predetermined inspection time plan until the entire processing cycle is completed.

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