Five-spindle-head RTCP parameter calibration and precision detection method based on tool setting gauge

Abstract

The invention relates to a five-spindle-head RTCP parameter calibration and precision detection method based on a tool setting gauge, and relates to the technical field of machine tool five-spindle-head precision calibration and detection. Comprising the steps of clamping a ball head detection rod, activating a tool setting gauge, executing a measurement detection program at a set angle, calculating and updating RTCP related parameters, automatically calculating geometric accuracy and outputting a result. According to the method, a written calibration algorithm is executed, and calibration detection is carried out by using a ball head detection rod clamped on a five-shaft-head main shaft and a tool setting gauge mounted in a machine tool working area; and calculating five-shaft-head RTCP parameters needing to be updated through an algorithm, testing related rotation geometric accuracy of the five shaft heads after data updating, and outputting a test report. Projects originally needing manual testing are optimized into automatic testing, interference such as manual misoperation is eliminated, efficiency is improved, the utilization value of the tool setting gauge is improved, and the cost of purchasing corresponding 3D measuring probes by users with automatic calibration requirements is also saved.

Description

Technical Field

[0001] The invention relates to the technical field of precision calibration and detection of a five-axis head of a machine tool, and in particular to a five-axis head RTCP parameter calibration and precision detection method based on a tool setting instrument. Background Art

[0002] Five-axis CNC machine tools can process complex surfaces by the deflection of the spindle, which does not require multiple clamping of parts, improves processing accuracy and shortens processing time. The assembly accuracy and performance of the five-axis head, which are closely related to the accuracy of the five-axis machine tool, and the calibration of the five-axis head tool tip following RTCP parameters will affect the use effect of the five-axis head.

[0003] Conventional five-axis head parameter calibration and geometric accuracy inspection require technicians to use inspection tools and measuring tools for manual inspection, which has certain requirements on the technical ability and experience of technicians. If automatic inspection is required, it is necessary to purchase expensive 3D probes and related software, which leads to an increase in production costs. In addition, the life of 3D probes will be greatly reduced in high temperature, high humidity, dust, oil, and vibration environments, leading to further increases in costs. In order to control costs and achieve efficient automatic inspection, we propose a five-axis head RTCP parameter calibration and accuracy inspection method based on a tool setter, which is suitable for laser tool setters and contact tool setters. Summary of the invention

[0004] The purpose of the present invention is to provide a five-axis head RTCP parameter calibration and accuracy detection method based on a tool setting instrument.

[0005] The technical problem solved by the present invention is that in the prior art, the parameter calibration and accuracy inspection of the five-axis head need to be performed manually or purchased at an expensive price, which leads to the problem of manual inspection errors or excessively high inspection costs.

[0006] The present invention can be implemented by the following technical solution: A five-axis head RTCP parameter calibration and accuracy detection method based on a tool setting instrument comprises the following steps:

[0007] Step 1: Coaxially clamp the ball head detection rod on the main axis of the five-axis head and set the tool setting instrument directly below it;

[0008] Step 2: Activate the test function of the tool setting instrument;

[0009] Step 3: Turn on the RTCP function to drive the five-axis head to perform 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 when the five-axis head rotates to 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 shafts, the distance between the two rotating shafts and the axis of the main shaft, and the distance between the axis of the rotating shaft 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 the RTCP function is turned on, the RTCP related parameters are preliminarily set using the installation dimensions to prevent exceeding the detection range of the tool setting instrument.

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

[0015] A further technical improvement of the present invention is that the process of calculating RTCP related parameters according to the Y-direction and Z-direction coordinate values ​​at the corresponding angle includes:

[0016]

[0017] Where, ΔL AC is the distance between the A-axis and the C-axis. The sign of the obtained value has directional significance. They represent the Y coordinates when the A axis rotates by θ1 and θ2 and the C axis is at zero degrees, and θ1 and θ2 are the angles in the A+ and A- directions respectively;

[0018]

[0019] Where, ΔL AS Indicates the distance between the A axis and the spindle axis. They represent the Z coordinates when the A axis rotates by θ3 and θ4 and the C axis is at zero degrees, and θ3 and θ4 are the angles in the A+ and A- directions respectively;

[0020]

[0021] Where, ΔL CSX , ΔL CSY It represents the distance between the C-axis and the spindle axis in the X and Y directions, ΔL ATZ Indicates the Z-direction distance from the A-axis axis to the ball head center of the ball head detection rod 4;

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

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

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

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

[0026] The present invention performs calibration detection by executing a pre-written calibration algorithm, using a ball head detection rod clamped on the five-axis head spindle and a tool setting instrument installed in the machine tool working area, and calculates the five-axis head RTCP parameters that need to be updated through the algorithm, and tests the relevant rotational geometric accuracy of the five-axis head after the data is updated and outputs a test report. The project that originally required manual testing is optimized to automatic testing, eliminating interference such as human misoperation, improving efficiency, increasing the utilization value of the tool setting instrument, and saving the cost of users with automatic calibration requirements to purchase corresponding 3D measurement probes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0028] Figure 1 It 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 It is a schematic diagram of the rotation axis marking of the present invention;

[0031] Figure 4 It is a schematic diagram of the marking of 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 It is a schematic diagram of the C-axis rotation angle state of the present invention;

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

[0035] In the figure: 1. Slide; 2. Five-axis head; 3. Spindle; 4. Ball head detection rod; 5. Measuring laser beam; 6. Tool setting instrument; 7. Rotation axis one; 8. Rotation axis two; 9. Rotation axis three; 10. Center line of the light beam. DETAILED DESCRIPTION

[0036] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0037] See also Figure 1-7 As shown, the five-axis head RTCP parameter calibration and accuracy detection method based on the tool setting instrument includes:

[0038] The hardware structure on which the method is based includes a five-axis head 2. In this embodiment, an AC swing head structure rotating around the X and Z axes is used as an example for explanation, and the principles of other structures are the same;

[0039] The five-axis head 2 is installed under the ram 1 of the machine tool. The machine tool drives the ram 1 and the five-axis head 2 to move in the three directions of X, Y and Z. The five-axis head 2 is responsible for driving the spindle 3 to rotate and swing in the directions of A and C. A ball head detection rod 4 is installed on the spindle 3. The ball head detection rod 4 is used 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 adopts a laser tool setter (the principle of using a contact tool setter is the same) as a high-precision automatic measurement tool. The contact coordinates of the ball head detection rod 4 along the Y and Z directions of the measuring laser beam 5 emitted by the tool setter 6 are recorded, and the RTCP calibration parameters and the five-axis linkage rotation accuracy are calculated based on the recorded contact coordinate data group.

[0041] The calculation process of RTCP calibration parameters is:

[0042] like Figure 2 As shown, the coordinates of the rotation axis 17 of the C axis are (Cx, Cy), the coordinates of the rotation axis 28 of the A axis are (Ay, Az), the coordinates of the rotation axis 39 of the spindle 3 when the A axis and the C axis are zero degrees origin are (Sx, Sy), and the coordinates of the beam center line 10 of the measuring laser beam 5 along the X direction are (Ly, Lz);

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

[0044] Since the rotation axis 1 7 is parallel to the rotation axis 3 9, the distance between them is divided into two components L in the X and Y directions. CSX , L CSY ;

[0045] The distance between the rotation axis 28 and the ball head center of the ball head detection rod 4 is L 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 the rotation axis 28 to the end face of the spindle 3 ASZ +The length of the ball head detection rod 4 L T+R -Ball head radius R T , measure the radius R of the laser beam 5 L =1 / 2*diameter of the measured laser beam 5.

[0046] The length L of the ball head detection rod 4 is T+R With ball head radius R T It can be obtained by querying the nameplate data of the ball head detection rod 4; considering the accuracy of the tool length, it is necessary to calculate the length to the center of the tool, 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 by the calibration program of the tool setting instrument 6;

[0047] Roughly fill in L according to the structure of the five-axis head 2 AC , L AS , L CSX , L CSY , L ATZ Length value (this dimension belongs to the installation dimension, and the corresponding five-axis head manufacturer will provide it) to prevent it from exceeding the detection range of the tool setting instrument. Then you can turn on the RTCP function (the difference is as follows Figure 7 As shown) and execute the automatic detection program cycle to perform accuracy measurement and data update. The algorithm is as follows:

[0048] Set an agreement is the Z direction data value measured by the tool setting instrument 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 when the A axis rotates to θ1 angle, and C0 is the position when the C axis rotates to 0 degrees, then:

[0049]

[0050] The sign of the obtained value has directional significance. θ1 and θ2 are the angles in the directions A+ and A- respectively. If the travel distance is sufficient, measurement at 90 degrees and -90 degrees is preferred.

[0051]

[0052] Among them, θ3 and θ4 are the angles in the A+ and A- directions respectively. If the travel is sufficient, it is preferred to measure at 90 degrees and -90 degrees;

[0053]

[0054] Among them, θ5 can be a large angle, that is, θ5 takes a value between 45-90 degrees, such as Figure 4 , Figure 5 , Figure 6 As shown;

[0055] Test process such as Figure 7 As shown:

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

[0057] Enable tool setting probe 6 and activate the test function;

[0058] according to Figure 5 and Figure 6 The process is tested separately Y A0C90 , Y A0C270 , Y A0C0 , Y A0C180 , Z A0C0 Then calculate ΔL AC , ΔL AS , ΔL CSX , ΔL CSY , ΔL ATZ The deviation value is updated to the RTCP related parameters that need to be set, and the RTCP parameter calibration of the five-axis head is completed;

[0059] Continue to execute the automatic detection program: according to the calibrated RTCP parameters of the updated data, calculate the theoretical coordinate values ​​of the contact between the ball head detection rod 4 and the laser beam in the Y and Z directions of the A and C axes at a specific angle;

[0060] Subtracting the theoretical coordinate value from the actual measured coordinate value can obtain the geometric accuracy error value of the five-axis head at each angle that requires geometric accuracy detection and output the result.

[0061] Technical term explanation:

[0062] The Rotating Tool Center Control (RTCP) function is a very important function of the five-axis linkage machine tool. The RTCP function greatly improves the efficiency of CNC machining code and programming. The RTCP function can convert the programming instructions based on the workpiece coordinate system into the motion instructions of the five motion axes in the machine tool coordinate system through kinematic transformation. Users do not need to pay attention to the complex motion of the five motion axes when programming. RTCP parameters are necessary parameters for motion transformation. The accuracy of RTCP parameter calibration directly affects the accuracy of tool tip trajectory control.

[0063] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A five-axis head RTCP parameter calibration and accuracy detection method based on a tool setting instrument, characterized in that: The steps include: Step 1: coaxially clamp a ball head detection rod (4) on the main shaft (3) of the five-axis head (2) and set a tool setting instrument (6) directly below the ball head detection rod (4); Step 2: Input the nameplate parameters of the ball head detection rod (4) and activate the test function of the tool setting instrument (6); Step 3: Turn on the RTCP function to drive the five-axis head to perform the measurement and detection program at the set angle; Step 4: Calculate and update RTCP related parameters; Step 5: Automatically calculate the geometric accuracy when the five-axis head rotates to the corresponding angle and output the result.

2. The five-axis head RTCP parameter calibration and accuracy detection method based on the tool setting instrument according to claim 1 is characterized in that: The RTCP related parameters that need to be calibrated include the distance between the axes of the two rotating shafts, the distance between the axes of the two rotating shafts and 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).

3. The five-axis head RTCP parameter calibration and accuracy detection method based on the tool setting instrument according to claim 2 is characterized in that: Before starting the RTCP function, the RTCP related parameters are preliminarily set using the installation dimensions to prevent exceeding the detection range of the tool setting probe (6).

4. The five-axis head RTCP parameter calibration and accuracy detection method based on the tool setting instrument according to claim 2 is characterized in that: When the five-axis head adopts the AC swing head structure, during the execution of the measurement and detection program, the Y-axis and Z-axis coordinate values ​​are collected respectively when the A-axis and C-axis rotate to the set angle, and the A-axis or C-axis itself remains at zero degrees when the other rotates to the set angle.

5. The five-axis head RTCP parameter calibration and accuracy detection method based on the tool setting instrument according to claim 4 is characterized in that: The process of calculating RTCP related parameters according to the Y-axis and Z-axis coordinate values ​​at the corresponding angle includes: Where, ΔL AC is the distance between the A-axis and the C-axis. The sign of the obtained value has directional significance. They represent the Y coordinates when the A axis rotates by θ1 and θ2 and the C axis is at zero degrees, and θ1 and θ2 are the angles in the A+ and A- directions respectively; Where, ΔL AS Indicates the distance between the A axis and the spindle axis. They represent the Z coordinates when the A axis rotates by θ3 and θ4 and the C axis is at zero degrees, and θ3 and θ4 are the angles in the A+ and A- directions respectively; Where, ΔL CSX , ΔL CSY It represents the distance between the C-axis and the spindle axis in the X and Y directions, ΔL ATZ Indicates the Z-direction distance from the A-axis axis to the ball head center of the ball head detection rod 4; Y A0C0 , Y A0C90 , Y A0C180 , Y A0C270 They represent the Y coordinates when the A axis is at zero degrees and the C axis rotates by 0 degrees, 90 degrees, 180 degrees, and 270 degrees respectively. Z A0C0 They respectively represent the Z coordinates when the A-axis is rotated by θ5 and 0 degrees and the C-axis is at zero degrees.

6. The five-axis head RTCP parameter calibration and accuracy detection method based on the tool setting instrument according to claim 5 is characterized in that: The angles of θ1, θ2, θ3 and θ4 are set to 90 degrees, and θ5 is set to a value between 45 and 90 degrees.

7. The five-axis head RTCP parameter calibration and accuracy detection method based on the tool setting instrument according to claim 5 is characterized in that: According to the updated RTCP parameters, the measured coordinate values ​​of the A-axis and the C-axis after they move the theoretical coordinate distances in the Y and Z directions at a specific angle are detected, and the accuracy error is obtained based on the difference between the measured coordinate values ​​and the theoretical coordinate values.

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