Automatic calibration method for in-machine measurement head of five-axis numerical control machine tool

Abstract

The application discloses a kind of five-axis numerical control machine tool in-machine probe automatic calibration method, comprising the following steps: in machine tool outside, to be calibrated probe combination to professional tool shank, and detect the length value of probe relative to tool shank mounting surface and measuring ball head diameter value;Probe is moved to the center of standard ring gauge fixed on machine tool rotary table surface, and this position is set as workpiece coordinate system after;Ring gauge surface is measured to obtain angular value, and after inputting the corresponding parameter table of machine tool workpiece coordinate system, probe radius calibration program is prepared and executed in machine tool operating system;After flattening probe, the highest point of probe side surface measures ring gauge upper surface plane, to obtain Z1 value;After erecting probe, the highest point of probe length direction measures ring gauge plane Z2 value of same point, to obtain probe tool length L=Z2-Z1.The present application can reduce the human participation in calibration process, improve the calibration accuracy of probe, calibration efficiency is higher, operation process is simpler, operation difficulty is smaller, can effectively improve the use efficiency of machine tool.

Description

Technical Field

[0001] This invention relates to the field of five-axis machine tool probe calibration technology, and in particular, to an automatic on-machine probe calibration method for five-axis CNC machine tools. Background Technology

[0002] With the development of CNC machine tool technology, high-precision five-axis CNC equipment has in-machine measurement capabilities. Its contact probe relies on the machine tool's servo system and coordinate system to achieve in-machine measurement. Before using in-machine measurement, the probe must be calibrated to reduce the impact of probe pre-stroke error.

[0003] Side head calibration is divided into length direction error calibration and diameter direction error calibration. Machine tools generally have a built-in diameter calibration program that can perform calibration automatically, but there is no standard method or calibration program for the length direction of the side head.

[0004] The conventional calibration method involves setting the probe length and radius in the CNC system's tool management before probe calibration. Then, the probe is moved to a standard tool setting block on the machine's reference plane. When a feeler gauge cannot pass between the tool setting block's end face and the probe, the calibrated probe length is the machine tool's Z-axis coordinate value minus the tool setting block's height. This probe calibration method is complex, difficult to operate, prone to error, and wastes valuable machine tool time. Summary of the Invention

[0005] This invention provides an automatic on-machine probe calibration method for five-axis CNC machine tools, which solves the technical problems of existing probe calibration methods being complex, difficult to operate, and prone to errors, thus wasting valuable machine tool time.

[0006] The technical solution adopted in this invention is as follows:

[0007] An automatic on-machine probe calibration method for a five-axis CNC machine tool is disclosed, used to calibrate the length of the probe and the radius of the ball head on the side. The calibration method includes the following steps: S20: The probe to be calibrated is assembled to a professional tool holder outside the machine tool, and the length value of the side head relative to the tool holder mounting surface and the diameter value of the ball head are detected and input into the length and diameter parameter table corresponding to the tool number of the professional tool holder installed on the machine tool; S30: The probe is moved to the center of a standard ring gauge fixed on the machine tool rotary table, and this position is set as the workpiece coordinate system. The X and Y coordinate values ​​of the machine tool are then... S40: Measure the surface of the ring gauge to obtain the angular value, and after inputting the parameter table corresponding to the machine tool workpiece coordinate system, compile and execute the probe radius calibration program in the machine tool operating system; S50: After flattening the probe, measure the plane of the upper surface of the ring gauge from the highest point of the probe side to obtain the Z-axis coordinate of the ring gauge surface, and input the measured Z1 actual value into the coordinate system; S60: After erecting the probe, measure the Z2 value of the same point on the plane of the ring gauge from the highest point of the probe length direction to obtain the probe tool length L = Z2 - Z1.

[0008] Further, step S20 specifically includes the following steps: S201: Assemble the probe onto the professional tool holder on a professional assembly tool outside the machine tool, place the professional tool holder on the tool setting instrument, detect the length value of the probe relative to the tool holder mounting surface and measure the diameter value of the ball head, and finally print the length and diameter values ​​on a label and affix it to the professional tool holder; S203: Check the labels of the probe length and diameter values ​​affixed to the professional tool holder, and input the probe length value and the ball head radius value on the label into the corresponding tool number length and diameter parameter table of the machine tool.

[0009] Furthermore, after completing step S201 and before proceeding to step S203, the following step is also included: S202: Install the professional tool holder with the side head into the machine tool magazine, and make the dial indicator head contact the measuring ball head of the probe, press the dial indicator down by 0.01mm, and then use the machine tool handwheel to rotate the spindle to check the runout of the dial indicator, the error of which is no more than 4μm.

[0010] Further, step S30 specifically includes the following steps: S301: Manually operate the machine tool handwheel to move the probe to the visually observed center of the ring gauge, and set this position as the workpiece coordinate system; S302: Input the machine tool X and Y coordinate values ​​into the X and Y parameter tables corresponding to the machine tool coordinate system respectively.

[0011] Further, step S40 specifically includes the following steps: S401: Use the two-point method to measure the surface of the ring gauge, take it as the angular direction of the ring gauge, and input the angular direction value into the parameter table corresponding to the machine tool workpiece coordinate system; S402: After positioning the probe to a certain depth within the visually observed center of the ring gauge, compile and execute the probe radius calibration program in the machine tool operating system.

[0012] Further, step S50 specifically includes the following steps: S501: Using the coordinate system rotation positioning function, rotate the workpiece coordinate system by -90° along the A-axis to realize the vertical-horizontal conversion of the machine tool; S502: Use the highest point of the side of the probe that has been calibrated to measure the plane of the upper surface of the ring gauge. After the measurement is completed, update the workpiece coordinate system and input the measured Z1 actual value into the coordinate system to obtain the Z-axis coordinate of the ring gauge surface.

[0013] Further, step S60 specifically includes the following steps: S601: After obtaining the Z-axis coordinate of the ring gauge plane from step S50, rotate the workpiece coordinate system to the initial state of 0° on the A-axis; S602: Measure the Z2 value of the same point on the ring gauge plane using the highest point of the probe length direction; S603: Calculate the probe tool length L = Z2 - Z1 based on the Z1 value of step S50.

[0014] Furthermore, before step S20, the procedure includes step S10: fixing a standard ring gauge to the machine tool rotary table using a magnetic block, and making the end face of the ring gauge perpendicular to the Z-axis of the machine tool.

[0015] Furthermore, before step S10, the procedure also includes step S00: calibrating the machine tool accuracy.

[0016] Further, step S00 specifically includes the following steps: S001: check and adjust the levelness accuracy of the turntable surface; S002: check and compensate for the motion accuracy of the machine tool.

[0017] The present invention has the following beneficial effects:

[0018] This invention proposes a highly efficient automatic calibration method for probes on a five-axis CNC machine tool. By developing a measurement calibration program, the probe radius is first calibrated by automatically measuring the standard diameter of the machine tool's calibration ring gauge to calibrate the probe radius error. Next, the probe is leveled, and the position of the ring gauge plane is measured using the calibrated probe radius. Then, the probe is vertically aligned and measured at the same point on the ring gauge plane. Using the measured position of the ring gauge plane as a reference, the probe length is calculated, which is the more accurate probe length calibrated on the machine tool. The calibration process of this invention is automatically completed by the machine tool according to the programmed instructions. The equipment automatically calibrates the probe length, reducing human intervention and improving the calibration accuracy. Compared to manual calibration, this method is more efficient, simpler, and less difficult to operate, effectively shortening calibration time and improving the machine tool's utilization efficiency.

[0019] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a schematic diagram illustrating the probe runout during dial indicator calibration;

[0022] Figure 2 This is a schematic diagram of the probe moving ring gauge center;

[0023] Figure 3 This is a schematic diagram of the ring gauge angular alignment.

[0024] Figure 4 This is a schematic diagram of probe radius calibration;

[0025] Figure 5 yes Figure 4 A schematic diagram of the left-side view structure;

[0026] Figure 6 This is a schematic diagram of the plane position for measuring the probe's radius direction;

[0027] Figure 7 This is a schematic diagram of the plane position for measuring the length of the probe.

[0028] Legend

[0029] 10. Probe; 11. Measuring ball head; 20. Ring gauge; 30. Dial indicator; 40. Professional tool holder. Detailed Implementation

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0031] Reference Figure 1-7 A preferred embodiment of the present invention provides an automatic on-machine calibration method for a five-axis CNC machine tool, used to calibrate the length of the probe 10 and the radius of the ball head 11 on the side. The calibration method includes the following steps:

[0032] S20: Outside the machine tool, assemble the probe 10 to be calibrated to the professional tool holder 40, and after detecting the length value of the side head relative to the tool holder mounting surface and the diameter value of the measuring ball head 11, input them into the length and diameter parameter table of the corresponding tool number of the professional tool holder installed on the machine tool.

[0033] S30: Move the probe 10 to the center of the standard ring gauge 20 fixed on the machine tool turntable, and set this position as the workpiece coordinate system. Then, input the X and Y coordinate values ​​of the machine tool into the X and Y parameter table corresponding to the machine tool coordinate system.

[0034] S40: Measure the surface of ring gauge 20 to obtain the angular value, and after inputting the parameter table corresponding to the machine tool workpiece coordinate system, compile and execute the probe 10 radius calibration program in the machine tool operating system;

[0035] S50: After flattening the probe 10, measure the plane of the upper surface of the ring gauge 20 from the highest point of the side of the probe 10 to obtain the Z-axis coordinate of the ring gauge 20 surface, and input the measured actual value of Z1 into the coordinate system.

[0036] S60: After erecting the probe 10, measure the Z2 value at the same point on the plane of the ring gauge 20 at the highest point in the length direction of the probe 10 to obtain the tool length L of the probe 10 = Z2 - Z1.

[0037] This invention proposes a highly efficient automatic calibration method for probes on a five-axis CNC machine tool. By developing a measurement calibration program, the probe radius is first calibrated by automatically measuring the standard diameter of the machine tool's calibration ring gauge to calibrate the probe radius error. Next, the probe is leveled, and the position of the ring gauge plane is measured using the calibrated probe radius. Then, the probe is vertically aligned and measured at the same point on the ring gauge plane. Using the measured position of the ring gauge plane as a reference, the probe length is calculated, which is the more accurate probe length calibrated on the machine tool. The calibration process of this invention is automatically completed by the machine tool according to the developed program. The equipment automatically calibrates the length of the probe 10, reducing human intervention and improving the calibration accuracy. Compared to manual calibration, this method is more efficient, simpler to operate, and less difficult to perform, effectively shortening calibration time and improving the machine tool's utilization efficiency.

[0038] Optionally, step S20 specifically includes the following steps:

[0039] S201: Assemble the probe 10 onto the professional tool holder on a professional assembly tool outside the machine tool, place the professional tool holder on the tool setting instrument, detect the length value of the side head relative to the tool holder mounting surface and measure the diameter value of the ball head 11, and finally print the length value and diameter value on the label paper and stick it onto the professional tool holder.

[0040] S203: Check the labels on the professional tool holder for the length and diameter values ​​of the probe 10 and the radius values ​​of the measuring ball 11. Enter the length and diameter parameter table of the corresponding tool number on the machine tool. After entering the values, carefully check whether the values ​​are correct.

[0041] Optionally, after completing step S201 and before proceeding to step S203, the following step is also included:

[0042] S202: Install the professional tool holder with the side head into the machine tool tool magazine, and contact the dial indicator 30 with the measuring ball head 11 of the probe 10, press the dial indicator 30 down by 0.01mm, and then use the machine tool handwheel to rotate the spindle. Figure 1 As shown, the runout of the dial indicator 30 was checked, and its error was no greater than 4μm.

[0043] Optionally, step S30 specifically includes the following steps:

[0044] S301: Manually operate the machine tool handwheel to move the probe 10 to the visually approximate center of the ring gauge 20, such as... Figure 2 As shown, this position is set as the workpiece coordinate system;

[0045] S302: Input the X and Y coordinate values ​​of the machine tool into the X and Y parameter tables corresponding to the machine tool coordinate system, respectively.

[0046] Optionally, step S40 specifically includes the following steps:

[0047] S401: Use the two-point method to measure the surface of ring gauge 20, taking it as the angular direction for measuring ring gauge 20, such as... Figure 3 As shown, the angular value is input into the parameter table corresponding to the machine tool workpiece coordinate system; although the length of probe 10 has not been calibrated at this time, the angular value is calculated at the same contact point in the probe length direction, and the pre-stroke error can be canceled out.

[0048] S402: Position the probe 10 to a certain depth within the visually estimated center of the ring gauge 20, such as... Figure 4 and Figure 5 As shown, the probe radius calibration program is compiled and executed in the machine tool operating system. Since the probe radius calibration program contains a model search function, the probe pre-stroke is automatically calibrated after measuring and calculating the center position of the ring gauge.

[0049] Optionally, step S50 specifically includes the following steps:

[0050] S501: Using the coordinate system rotation positioning function, rotate the workpiece coordinate system by -90° along the A-axis to realize the vertical-horizontal conversion of the machine tool;

[0051] S502: Measure the upper surface plane of the ring gauge 20 using the highest point of the side of the probe 10, which has already been calibrated for radius. Figure 6 As shown, after measuring and updating the workpiece coordinate system, input the measured actual value of Z1 into the coordinate system to obtain the Z-axis coordinate of the ring gauge 20 surface.

[0052] Optionally, step S60 specifically includes the following steps:

[0053] S601: After obtaining the Z-axis coordinate of the ring gauge 20 plane from step S50, rotate the workpiece coordinate system back to the initial state of 0° on the A-axis;

[0054] S602: Measure the Z2 value at the same point on the plane of ring gauge 20 using the highest point of probe 10 along its length direction. Figure 3 As shown;

[0055] S603: Based on the Z1 value in step S50, calculate the tool length L of probe 10 = Z2 - Z1.

[0056] Optionally, before proceeding to step S20, the following step is also included:

[0057] S10: Fix the standard ring gauge 20 to the machine tool rotary table using a magnetic block, and make the end face of the ring gauge 20 perpendicular to the machine tool Z axis.

[0058] Optionally, before performing step S10, the following step is also included:

[0059] S00: Calibrate the machine tool's accuracy. Side head calibration is only possible while the machine tool is running, and the accuracy of the machine tool determines the accuracy of the side head calibration. Therefore, during side head calibration, the machine tool's accuracy should be calibrated periodically to minimize the machine tool's inherent errors.

[0060] In this optional solution, step S00 specifically includes the following steps:

[0061] S001: Check and adjust the levelness accuracy of the rotary table surface; the specific operation is as follows: check the levelness accuracy of the machine tool rotary table surface, use an electronic level measuring instrument to measure the levelness of the rotary table surface, before measurement, use a spiral spring to polish the surface of the worktable to remove surface impurities and reduce measurement error, select four symmetrical positions at the largest diameter of the rotary table, and place the electronic level measuring instrument at the four points respectively. The detection error of the flatness of the rotary table should not be greater than 0.008mm. If this requirement is not met, the level of the machine tool should be adjusted to ensure the levelness accuracy of the rotary table.

[0062] S002: Check and compensate for machine tool motion accuracy. Specifically, the positional accuracy of a CNC machine tool is a crucial indicator. As the machine tool is used for longer periods, its transmission backlash, lead screw pitch error, and other errors will gradually increase. Using a laser interferometer, linear errors in the X, Y, and Z axes can be quickly measured and compensated, improving the machining accuracy of the machine tool.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for automatic calibration of a machine tool head of a five-axis CNC machine, characterized in that, The calibration method for calibrating the length of the probe (10) and the radius of the measuring ball head (11) on the side includes the following steps: S20: Outside the machine tool, assemble the probe (10) to be calibrated to the professional tool holder, and after detecting the length value of the side head relative to the tool holder mounting surface and the diameter value of the measuring ball head (11), input them into the length and diameter parameter table of the corresponding tool number of the professional tool holder installed on the machine tool. S30: Move the probe (10) to the center of the standard ring gauge (20) fixed on the machine tool turntable, and set this position as the workpiece coordinate system. Then input the machine tool X and Y coordinate values ​​into the X and Y parameter table corresponding to the machine tool coordinate system. S40: Measure the surface of the ring gauge (20) to obtain the angular value, and input the parameter table corresponding to the machine tool workpiece coordinate system. Then, compile and execute the probe (10) radius calibration program in the machine tool operating system. S50: After flattening the probe (10), measure the plane of the upper surface of the ring gauge (20) by the highest point of the side of the probe (10) to obtain the Z-axis coordinate of the ring gauge (20) surface, and input the measured Z1 actual value into the coordinate system; S60: After erecting the probe (10), measure the Z2 value of the same point on the plane of the ring gauge (20) at the highest point of the probe (10) in the length direction, so as to obtain the tool length L of the probe (10) = Z2 - Z1.

2. The automatic calibration method of in-machine measuring head of five-axis CNC machine tool according to claim 1, characterized in that, Step S20 specifically includes the following steps: S201: On a professional assembly tool outside the machine tool, assemble the probe (10) to the professional tool holder, place the professional tool holder on the tool setting instrument, detect the length value of the side head relative to the tool holder mounting surface and measure the diameter value of the ball head (11), and finally print the length value and diameter value on the label paper and paste it on the professional tool holder. S203: Check the labels on the professional tool holder for the length and diameter values ​​of the probe (10) and the radius values ​​of the measuring ball (11) on the labels, and enter them into the corresponding tool number length and diameter parameter table of the machine tool.

3. The automatic calibration method of in-machine measuring head of five-axis CNC machine tool according to claim 2, characterized in that, After completing step S201 and before proceeding to step S203, the following steps are also included: S202: Install the professional tool holder with the side head into the machine tool tool magazine, and put the dial indicator (30) head into contact with the measuring ball head (11) of the probe (10), press the dial indicator (30) down by 0.01mm, and then use the machine tool handwheel to rotate the spindle to check the runout of the dial indicator (30), and its error is no more than 4μm.

4. The method for automatic on-machine probe calibration of a five-axis CNC machine tool according to claim 1, characterized in that, Step S30 specifically includes the following steps: S301: Manually operate the machine tool handwheel to move the probe (10) to the center of the visually inspected ring gauge (20) and set this position as the workpiece coordinate system; S302: Input the X and Y coordinate values ​​of the machine tool into the X and Y parameter tables corresponding to the machine tool coordinate system, respectively.

5. The automatic calibration method of in-machine measuring head of five-axis CNC machine tool according to claim 1, characterized in that, Step S40 specifically includes the following steps: S401: Use the two-point method to measure the surface of the ring gauge (20), take it as the angular direction of the ring gauge (20), and input the angular direction value into the parameter table corresponding to the machine tool workpiece coordinate system; S402: After positioning the probe (10) to a certain depth within the center of the circle as visually determined by the ring gauge (20), compile and execute the probe (10) radius calibration program in the machine tool operating system.

6. The automatic calibration method of in-machine measuring head of five-axis CNC machine tool according to claim 1, characterized in that, Step S50 specifically includes the following steps: S501: Using the coordinate system rotation positioning function, rotate the workpiece coordinate system by -90° along the A-axis to realize the vertical-horizontal conversion of the machine tool; S502: Use the highest point of the side of the probe (10) that has been calibrated to measure the plane of the upper surface of the ring gauge (20). After the measurement is completed, update the workpiece coordinate system and input the measured Z1 actual value into the coordinate system to obtain the Z-axis coordinate of the ring gauge (20) surface.

7. The automatic calibration method of in-machine measuring head of five-axis CNC machine tool according to claim 1, characterized in that, Step S60 specifically includes the following steps: S601: After obtaining the Z-axis coordinate of the ring gauge (20) plane from step S50, rotate the workpiece coordinate system back to the initial state of 0° on the A-axis; S602: Use the highest point of the probe (10) in the length direction to measure the Z2 value of the same point on the plane of the ring gauge (20); S603: Based on the Z1 value in step S50, calculate the length L of the probe (10) tool = Z2 - Z1.

8. The method for automatic on-machine probe calibration of a five-axis CNC machine tool according to claim 1, characterized in that, Before step S20, the following steps are also included: S10: Fix the standard ring gauge (20) to the machine tool turntable surface using a magnetic block, and make the end face of the ring gauge (20) perpendicular to the Z-axis of the machine tool.

9. The automatic calibration method of a five-axis CNC machine tool on-machine probe according to claim 8, characterized in that, Before step S10, the following steps are also included: S00: Calibrate the machine tool accuracy.

10. The automatic calibration method of a five-axis CNC machine tool on-machine probe according to claim 9, characterized in that, Step S00 specifically includes the following steps: S001: Check and adjust the levelness accuracy of the turntable surface; S002: Check and compensate for the machine tool motion accuracy.

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