Five-axis head RTCP parameter calibration and precision detection method based on tool ball bar

Abstract

The present application relates to a five-axis head RTCP parameter calibration and precision detection method based on a tool setting gauge, and relates to the technical field of machine tool five-axis head precision calibration and detection; including clamping a ball head detection rod, activating the tool setting gauge, executing a measurement and detection program at a set angle, calculating and updating RTCP related parameters, automatically calculating geometric precision and outputting results. The present application executes the prepared calibration algorithm, uses the ball head detection rod clamped on the spindle of the five-axis head and the tool setting gauge installed in the working area of the machine tool for calibration and detection, calculates the five-axis head RTCP parameters that need to be updated through the algorithm, tests the related rotary geometric precision of the five-axis head after the data is updated, and outputs a test report. The items that originally need to be tested manually are optimized for automatic testing, human errors and other disturbances are excluded, the efficiency is improved, the utilization value of the tool setting gauge is improved, and the cost of purchasing the corresponding 3D measurement probe for users with automatic calibration needs is saved.

Description

Technical Field

[0001] This invention relates to the field of five-axis head precision calibration and testing technology for machine tools, specifically to a method for five-axis head RTCP parameter calibration and precision testing based on a tool setter. Background Technology

[0002] Five-axis CNC machine tools can perform machining of complex curved surfaces by tilting the spindle, eliminating the need for multiple clamping of parts, thus improving machining accuracy and shortening machining time. The assembly accuracy and performance of the five-axis head, as well as the calibration of the five-axis head tool tip following RTCP parameters, which are closely related to the accuracy of the five-axis machine tool, will affect the performance of the five-axis head.

[0003] Conventional five-axis head parameter calibration and geometric accuracy inspection require manual inspection by technicians using gauges and measuring tools, demanding a certain level of technical skill and experience. Automated inspection necessitates the purchase of expensive 3D probes and related software, increasing production costs. Furthermore, the lifespan of 3D probes is significantly reduced in environments with high temperature, high humidity, dust, oil, and vibration, further increasing costs. To control costs and achieve efficient automated inspection, we propose a five-axis head RTCP parameter calibration and accuracy inspection method based on a tool setter. This method is applicable to both laser tool setters and contact tool setters. Summary of the Invention

[0004] The purpose of this invention is to provide a method for calibrating and measuring the accuracy of five-axis head RTCP parameters based on a tool setter.

[0005] The technical problem solved by this invention is that in the prior art, the calibration and accuracy inspection of five-axis head parameters need to be performed manually or purchased at a high cost, which leads to problems such as manual inspection errors or excessive inspection costs.

[0006] This invention can be achieved through the following technical solution: a five-axis head RTCP parameter calibration and accuracy detection method based on a tool setter, comprising the following steps:

[0007] Step 1: Coaxially mount the ball head detection bar on the spindle of the five-axis head and set up the tool setter directly below it;

[0008] Step 2: Activate the testing function of the tool setter;

[0009] Step 3: Enable the RTCP function to drive the five-axis head to execute the measurement and detection program at the set angle;

[0010] Step 4: Calculate and update RTCP related parameters;

[0011] Step 5: Automatically calculate the geometric accuracy of the five-axis head when it rotates at the corresponding angle and output the result.

[0012] A further technical improvement of the present invention is that the RTCP-related parameters that need to be calibrated include the distance between the axes of the two rotating axes, the distance between the two rotating axes and the axis of the main shaft, and the distance between the axis of the rotating axis directly loaded on the main shaft and the center of the ball head of the ball head detection rod.

[0013] A further technical improvement of the present invention is that: before activating the RTCP function, the relevant parameters of RTCP are initially set using the installation dimensions to prevent them from exceeding the detection range of the tool setter.

[0014] A further technical improvement of the present invention is that when the five-axis head adopts the AC oscillating head structure, during the execution of the measurement and detection program, the Y and Z coordinate values ​​of the A-axis and C-axis are collected respectively when they rotate to a set angle, and the A-axis or C-axis remains at zero degrees when the other rotates to the set angle.

[0015] A further technical improvement of the present invention lies in the fact that the process of calculating RTCP-related parameters based on the Y-axis and Z-axis coordinate values ​​at the corresponding angles includes:

[0016]

[0017] Where, ΔL AC This represents the distance between the A-axis and C-axis lines; the sign of the resulting value indicates direction. These represent the Y-coordinates when the A-axis is rotated by angles θ1 and θ2, respectively, and the C-axis is at zero degrees. θ1 and θ2 are the angles in the A+ and A- directions, respectively.

[0018]

[0019] Where, ΔL AS This indicates the distance between the A-axis and the main spindle axis. These represent the Z-axis coordinates when the A-axis is rotated by angles θ3 and θ4 respectively, and the C-axis is at zero degrees. θ3 and θ4 are the angles in the A+ and A- directions, respectively.

[0020]

[0021] Where, ΔL CSX ΔL CSY ΔL represents the components of the distance between the C-axis and the principal axis in the X and Y directions. ATZ This represents the Z-axis distance from the A-axis line to the center of the ball head of the ball head detection rod 4;

[0022] Y A0C0 Y A0C90 Y A0C180 Y A0C270 These represent the Y-coordinates when the A-axis is at zero degrees and the C-axis is rotated by 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively. Z A0C0 These represent the Z-axis coordinates when the A-axis is rotated by θ5 and 0 degrees, respectively, and the C-axis is at zero degrees.

[0023] A further technical improvement of the present invention is that the angles θ1, θ2, θ3, and θ4 are set to 90 degrees, and θ5 is taken between 45 and 90 degrees.

[0024] A further technical improvement of the present invention is that: the measured coordinate values ​​of the A-axis and C-axis after moving the theoretical coordinate distance in the Y and Z directions at a specific angle are detected according to the updated RTCP parameters, and the accuracy error is obtained based on the difference between the measured coordinate values ​​and the theoretical coordinate values.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention performs calibration testing by executing a pre-written calibration algorithm, using a ball joint probe clamped on the spindle of a five-axis head and a tool setter installed in the machine tool's working area. The algorithm calculates the RTCP parameters of the five-axis head that need updating, and after the data update, tests the relevant rotational geometric accuracy of the five-axis head and outputs a test report. This optimizes what was originally a manual testing process into an automated one, eliminating interference from human error, improving efficiency, enhancing the utilization value of the tool setter, and saving users with automatic calibration needs the cost of purchasing corresponding 3D measurement probes. Attached Figure Description

[0027] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0029] Figure 2 This is a schematic diagram of the clamping state of the ball head detection rod of the present invention;

[0030] Figure 3 This is a schematic diagram of the rotation axis markings of the present invention;

[0031] Figure 4 This is a schematic diagram showing the relevant distance parameters of the present invention;

[0032] Figure 5 This is a schematic diagram of the A-axis rotation angle state of the present invention;

[0033] Figure 6 This is a schematic diagram of the C-axis rotation angle state of the present invention;

[0034] Figure 7 This is a schematic diagram showing the trajectory difference before and after the five-axis head RTCP function of the present invention is enabled.

[0035] In the diagram: 1. Slide; 2. Five-axis head; 3. Spindle; 4. Ball head detection bar; 5. Measuring laser beam; 6. Tool setter; 7. Rotation axis one; 8. Rotation axis two; 9. Rotation axis three; 10. Beam centerline. Detailed Implementation

[0036] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0037] Please see Figure 1-7 As shown, the method for calibrating and measuring the accuracy of the five-axis head RTCP parameters based on the tool setter includes...

[0038] The hardware structure on which this method is based includes a five-axis head 2. In this embodiment, an AC oscillating head structure that rotates around the X and Z axes is used as an example for illustration. The principle of other structures is the same.

[0039] The five-axis head 2 is installed below the slide 1 of the machine tool. The machine tool drives the slide 1 and the five-axis head 2 to move in the X, Y and Z directions. The five-axis head 2 is responsible for driving the spindle 3 to rotate and swing in the A and C directions. A ball head detection bar 4 is installed on the spindle 3. The ball head detection bar 4 serves as a gauge for RTCP parameter calibration and five-axis linkage rotation accuracy.

[0040] A tool setter 6 is placed directly below the ball head detection rod 4. In this embodiment, the tool setter 6 uses a laser tool setter (the principle of which is the same as that of a contact tool setter) as a high-precision automatic measuring tool. It records the contact coordinates of the ball head detection rod 4 with the measuring laser beam 5 emitted by the tool setter 6 along the Y and Z directions, and calculates the RTCP calibration parameters and the five-axis linkage rotation accuracy based on the recorded contact coordinate data.

[0041] The calculation process for RTCP calibration parameters is as follows:

[0042] like Figure 2 As shown, let the coordinates of the rotation axis 7 of the C-axis be (Cx, Cy), the coordinates of the rotation axis 8 of the A-axis be (Ay, Az), the coordinates of the rotation axis 9 of the main axis 3 when the A-axis and C-axis are at the zero-degree origin be (Sx, Sy), and the coordinates of the beam center line 10 of the measuring laser beam 5 along the X direction be (Ly, Lz).

[0043] To determine the RTCP calibration parameters, i.e., the coordinate conversion of the programming rotation center of the tool center or tool tip, the following information needs to be determined: the distance L between rotation axis 1 (7) and rotation axis 2 (8). AC The distance L between rotation axis 2 (8) and rotation axis 3 (9) AS The distance L between rotation axis 7 and rotation axis 9 CS ;

[0044] Since the rotation axis 7 and the rotation axis 9 are parallel, the distance between them is divided into two components, L in the X and Y directions. CSX L CSY ;

[0045] The distance L between the rotation axis 28 and the center of the ball head of the ball head detection rod 4 is AT And L AT The components L in the Y and Z directions ATY and L ATZ Composition, L ATY That is, L AS L ATZ =Z-direction distance L from axis of rotation 28 to end face of spindle 3 ASZ +Length L of ball head detection rod 4 T+R -Ball head radius R T Measure the radius R of laser beam 5 L = 1 / 2 * the diameter of the measured laser beam 5.

[0046] The length L of the aforementioned ball head detection rod 4 T+R With the ball head radius R T The data can be obtained from the nameplate data of the ball head detection rod 4; considering the accuracy of the tool length, the length to the center of the tool needs to be calculated, so the tool parameters need to be input; the diameter of the measuring laser beam 5 of the tool setting instrument 6 can be measured through the calibration program of the tool setting instrument 6;

[0047] Based on the structure of the five-axis head 2, roughly fill in L. AC L AS L CSX L CSY L ATZ The length value (this dimension is the installation dimension and will be provided by the manufacturer of the corresponding five-axis head) is used to prevent exceeding the detection range of the tool setter. Afterwards, the RTCP function can be enabled (the difference is as follows). Figure 7 (As shown) and executes an automatic detection program to perform accuracy measurement and data update in a loop. The algorithm is as follows:

[0048] Let's agree Let Z be the data value measured by the tool setter 6 (i.e., the measurement value when the bottom of the ball of the ball head detection rod 4 touches the laser beam), where Aθ1 is the position of rotation of the A axis to the θ1 angle position, and C0 is the position of rotation of the C axis to the 0 degree position. Then we have:

[0049]

[0050] The positive and negative signs of the obtained values ​​have directional significance. θ1 and θ2 are the angles in the A+ and A- directions, respectively. If the travel is sufficient, it is preferable to measure at 90 degrees and -90 degrees.

[0051]

[0052] Where θ3 and θ4 are the angles in the A+ and A- directions, respectively. If the stroke is sufficient, it is preferable to measure 90 degrees and -90 degrees.

[0053]

[0054] Where θ5 is a large angle, that is, θ5 takes a value between 45 and 90 degrees, such as Figure 4 , Figure 5 , Figure 6 As shown;

[0055] The testing process is as follows Figure 7 As shown:

[0056] First, install the ball head detection rod 4 on the spindle 3 and activate the parameters such as the length and diameter of the ball head detection rod 4;

[0057] Enable the tool setter 6 and activate its testing function;

[0058] according to Figure 5 and Figure 6 The process is tested separately. Y A0C90 Y A0C270 Y A0C0 Y A0C180 , Z A0C0 The value is then used to calculate ΔL. AC ΔL AS ΔL CSX ΔL CSY ΔL ATZ The deviation value is then updated to the required RTCP parameters to complete the RTCP parameter calibration of the five-axis head.

[0059] Continue executing the automatic detection program: Based on the updated data and the calibration RTCP parameters, calculate the theoretical coordinate values ​​of the ball head detection rod 4 in contact with the laser beam at specific angles in the Y and Z directions of the A-axis and C-axis.

[0060] Subtracting the theoretical coordinates from the actual measured coordinates yields the geometric accuracy error of the five-axis head at various angles requiring specific geometric accuracy, and the results are then output.

[0061] Technical Terminology Explanation:

[0062] Rotary Tool Center Control (RTCP) is a crucial function for five-axis CNC machine tools, significantly improving the efficiency of CNC machining code and programming. RTCP transforms workpiece-based coordinate system programming instructions into motion commands for the five axes in the machine tool coordinate system through kinematic transformations, freeing users from worrying about the complex movements of these axes during programming. RTCP parameters are essential for motion transformations, and their accuracy directly impacts the precision of tool tip trajectory control.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for calibrating and measuring the accuracy of five-axis head RTCP parameters based on a tool setter, characterized in that: Includes the following steps: Step 1: Coaxially mount the ball head detection bar (4) on the spindle (3) of the five-axis head (2) and set the tool setter (6) directly below it; Step 2: Input the nameplate parameters of the ball head test bar (4) and activate the test function of the tool setting instrument (6); Step 3: Enable the RTCP function to drive the five-axis head to execute the measurement and detection program at the set angle; When the five-axis head adopts the AC oscillating head structure, during the execution of the measurement and detection program, the Y and Z coordinate values ​​of the A-axis and C-axis are collected respectively when they rotate to the set angle, and the A-axis or C-axis remains at zero degrees when the other rotates to the set angle. Step 4: Calculate and update RTCP related parameters; The RTCP-related parameters that need to be calibrated include the distance between the axes of the two rotating axes, the distance between the two rotating axes and the axis of the main shaft (3) respectively, and the distance between the axis of the rotating shaft directly loaded on the main shaft (3) and the center of the ball head of the ball head detection rod (4); The process of calculating RTCP-related parameters based on the Y-axis and Z-axis coordinates at the corresponding angles includes: ΔL AC = ; Where, ΔL AC This represents the distance between the A-axis and C-axis lines; the sign of the resulting value indicates direction. , These represent rotation along the A-axis. and The Y-coordinate when the angle and the C-axis are at zero degrees. and These are the angles in the A+ and A- directions, respectively. ΔL AS = ; Where, ΔL AS This indicates the distance between the A-axis and the main spindle axis. , These represent rotation along the A-axis. and The Z-coordinate when the angle is such that the C-axis is at zero degrees. and These are the angles in the A+ and A- directions, respectively. ΔL CSX = ; ΔL CSY = ; ΔL ATZ = ; Where, ΔL CSX ΔL CSY ΔL represents the components of the distance between the C-axis and the principal axis in the X and Y directions. ATZ This represents the Z-axis distance from the A-axis line to the center of the ball head of the ball head detection rod 4; , , , These represent the Y-coordinates when the A-axis is at zero degrees and the C-axis is rotated by 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively. , These represent rotation along the A-axis. and The Z-coordinate when the C-axis is at zero degrees; Step 5: Automatically calculate the geometric accuracy of the five-axis head when it rotates at the corresponding angle and output the result.

2. The method for calibrating and measuring the accuracy of five-axis head RTCP parameters based on a tool setter according to claim 1, characterized in that, Before enabling the RTCP function, the RTCP related parameters are initially set using the installation dimensions to prevent exceeding the detection range of the tool setter (6).

3. The method for calibrating and measuring the accuracy of five-axis head RTCP parameters based on a tool setter according to claim 1, characterized in that, The , The angle is set to 90 degrees. The value is between 45 and 90 degrees.

4. The method for calibrating and measuring the accuracy of five-axis head RTCP parameters based on a tool setter according to claim 1, characterized in that, The measured coordinate values ​​of the A-axis and C-axis after moving the theoretical coordinate distance in the Y and Z directions at a specific angle are detected according to the updated RTCP parameters, and the accuracy error is obtained based on the difference between the measured coordinate values ​​and the theoretical coordinate values.

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