A precision rapid automatic detection method for numerical control machine tool

Abstract

This invention relates to the field of CNC machine tool accuracy testing technology, and particularly to a rapid and automatic method for CNC machine tool accuracy testing. The method uses a single probe for CNC machine tool accuracy inspection. The probe is mounted on a tool measuring instrument, and a probe stylus is attached to the probe. The tool measuring instrument is used to obtain the installation dimension parameters of the probe and probe stylus, and the coaxiality of the probe stylus and tool axis is adjusted. The probe is placed in the CNC machine tool's tool magazine, and the installation dimension parameters are entered into the CNC system's tool list. The CNC machine tool is started, the probe is retrieved, and the spindle is oriented, with the rotary axis returning to its zero position. The probe is moved, and the constant error ΔQ at the distal and proximal ends of the probe stylus is measured. Based on the constant error ΔQ, the actual accuracy of the machine tool and the zero-point positioning accuracy of the rotary axis are obtained. This technical solution uses a probe for accuracy testing. The probe is a standard accessory for CNC machine tools, requiring no additional devices and resulting in extremely low implementation costs.

Description

Technical Field

[0001] This invention relates to the field of CNC machine tool accuracy testing technology, and in particular to a rapid and automatic method for CNC machine tool accuracy testing. Background Technology

[0002] With the increasing domestic demand for automation, informatization, and intelligence in CNC machine tools, their functions are trending towards unmanned operation. Accuracy and reliability, two key indicators of CNC machine tools, have become particularly prominent, with accuracy directly affecting the machining precision and surface quality of parts. Currently, production lines consisting of single machines are in operation in many parts of China. The increase in the number of machine tools necessitates automated accuracy testing of CNC machine tools. Eliminating human intervention, accuracy checks can be carried out at any time.

[0003] Currently, the inspection of zero-point accuracy of machine tool rotary axes, both domestically and internationally, mainly relies on manual inspection. This involves manually adjusting the position using tools such as inspection bars and dial indicators, and then observing the changes in readings to obtain the result. The problem with this method is that it results in long downtime, limits the frequency of inspection, and makes it difficult to detect problems in a timely manner. A small number of methods use ball joints, advanced sensors, and computers, but these methods require highly skilled personnel, and the equipment needs to be set up and adjusted, making the inspection work difficult. In addition, some foreign machine tool manufacturers have developed laser online machine tool accuracy inspection systems, but the application cost is very high, making it difficult to widely and quickly apply them. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a rapid and automatic method for detecting the accuracy of CNC machine tools, as detailed below:

[0005] Using a single probe to check the accuracy of CNC machine tools includes the following steps:

[0006] S1, Install the probe on the clamping mechanism of the tool measuring instrument, and assemble the probe stylus on the probe;

[0007] S2. Using a tool measuring instrument, obtain the installation dimension parameters of the probe and stylus, and adjust the coaxiality of the probe and stylus with the tool axis.

[0008] S3, remove the probe from the tool measuring instrument and place it in the CNC machine tool tool magazine, and enter the corresponding installation dimension parameters in the CNC system tool list;

[0009] S4, start the CNC machine tool, the CNC machine tool executes the command, brings up the probe and orients the spindle, and the rotary axis returns to the zero position;

[0010] S5 moves the probe by standard CNC machine tool commands, and uses the distal and proximal ends of the probe to touch and measure the same detection point, measuring the constant error ΔQ between the distal and proximal ends;

[0011] S6 obtains the actual accuracy of the machine tool and the zero-point positioning accuracy of the rotary axis based on a constant error ΔQ.

[0012] Preferably, in step S1, the length S of the probe is ≥ 100 mm.

[0013] Preferably, in step S5, the proximal end of the probe is the end closest to the probe transmitter, and a metal threaded connector is used to trigger the probe; the distal end of the probe uses a ruby ​​ball head.

[0014] Preferably, in step S2, the installation dimension parameters include the total length of the probe and stylus, the radius of the ruby ​​ball head of the stylus, and the coaxiality of the stylus and the tool holder.

[0015] Preferably, in step S3, the method for adjusting the coaxiality of the probe and stylus is as follows: rotate the clamping mechanism of the tool measuring instrument, and adjust the coaxiality of the probe and stylus with the tool holder to within 0.01mm based on the reading of the change in the projected movement of the tool measuring instrument.

[0016] Preferably, in step S6, the constant error ΔQ is incorporated into the NC measurement program to calculate the actual accuracy of the machine tool.

[0017] Preferably, in step S6, the method for obtaining the zero-point positioning accuracy of the rotary shaft is as follows: the probe is moved by the standard command of the CNC machine tool, and the same detection point is measured again by the far end and the near end of the probe. The measured values ​​P1 and P2 of the far end and the near end are recorded. The difference between P1 and P2 minus ΔQ is the zero-point positioning accuracy of the rotary shaft.

[0018] Preferably, in step S5, the constant error ΔQ includes the error value ΔY1 in the Y-axis direction and the error value ΔX1 in the X-axis direction measured at the distal and proximal ends of the probe.

[0019] The method to obtain ΔY1 is as follows: find a specific point in the Y / Z plane of the machine tool table, and use the far end and near end of the probe to complete the measurement work in the Y / Z plane, and record the measurement difference ΔY1 between the two measurement results.

[0020] The method for obtaining ΔX1 is as follows: find a specific point in the X / Z plane of the machine tool worktable, and use the far end and near end of the probe to complete the measurement work in the X / Z plane, and record the measurement difference ΔX1 between the two measurement results.

[0021] The beneficial effects of this technical solution are:

[0022] This technical solution uses a probe for precision inspection. The probe is a standard accessory for CNC machine tools, requiring no additional devices and resulting in extremely low implementation costs. Secondly, this solution uses a single probe for CNC machine tool precision inspection, eliminating assembly errors caused by multiple probes and assembly processes, simplifying the inspection process and making the results more accurate and reliable. Thirdly, by utilizing the ruby ​​ball head at the distal end and the metal threaded connector at the proximal end of the probe, the zero-point positioning accuracy of the rotary axis can be accurately measured at both ends. This ingenious implementation requires minimal manual intervention, and subsequent measurements can be automated. The measurement results are also automatically stored in the NC measurement program, enabling traceability of accuracy and observation of the machine tool's accuracy change trend. Attached Figure Description

[0023] Figure 1 This is a structural schematic diagram of a CNC machine tool (horizontal machining center);

[0024] Figure 2 This is a schematic diagram of the probe's structure;

[0025] Figure 3 Schematic diagram of the principle of positioning and measuring a rotating axis;

[0026] Figure 4 Schematic diagram of the principle for measuring the parallelism between the main axis and the Z-axis;

[0027] In the picture:

[0028] 1. Probe; 2. Stylus; 3. Proximal end of stylus; 4. Distal end of stylus; 5. B-axis worktable; 6. A-axis rotation center. Detailed Implementation

[0029] To make the purpose, technical solution and advantages of the invention clearer, the technical solution of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the invention, but not all embodiments.

[0030] Therefore, the following detailed description of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0031] Example 1

[0032] This embodiment discloses a rapid and automatic method for detecting the accuracy of CNC machine tools. As a basic implementation scheme of this technical solution, the key point is to use a single probe to check the accuracy of CNC machine tools, including the following steps:

[0033] S1, Install the probe on the clamping mechanism of the tool measuring instrument, and assemble the probe stylus on the probe;

[0034] S2. Using a tool measuring instrument, obtain the installation dimension parameters of the probe and stylus, and adjust the coaxiality of the probe and stylus with the tool axis.

[0035] S3, remove the probe from the tool measuring instrument and place it in the CNC machine tool tool magazine, and enter the corresponding installation dimension parameters in the CNC system tool list;

[0036] S4, start the CNC machine tool, the CNC machine tool executes the command, brings up the probe and orients the spindle, and the rotary axis returns to the zero position;

[0037] S5 moves the probe by standard CNC machine tool commands, and uses the distal and proximal ends of the probe to touch and measure the same detection point, measuring the constant error ΔQ between the distal and proximal ends;

[0038] S6 obtains the actual accuracy of the machine tool and the zero-point positioning accuracy of the rotary axis based on a constant error ΔQ.

[0039] Example 2

[0040] This embodiment discloses a method for rapid and automatic accuracy detection of CNC machine tools. As a preferred implementation of this technical solution, it includes the following steps:

[0041] S1. The probe is mounted on the clamping mechanism of the tool measuring instrument, and a probe is assembled on the probe. To facilitate the calculation of measurement error values ​​in practical engineering applications, the length of the probe S is ≥ 100 mm. The proximal end of the probe is the end closest to the probe transmitter, which uses a metal threaded connector to trigger the probe. The distal end of the probe uses a ruby ​​ball head.

[0042] S2. Using a tool measuring instrument, obtain the installation dimension parameters of the probe and stylus, and adjust the coaxiality of the probe and stylus with the tool shaft. The installation dimension parameters include the total length of the probe and stylus, the radius of the ruby ​​ball head of the stylus, and the coaxiality of the stylus with the tool holder. The method for adjusting the coaxiality of the probe and stylus is as follows: rotate the clamping mechanism of the tool measuring instrument, and adjust the coaxiality of the probe and stylus with the tool holder to a range of 0.01mm based on the reading of the change in the projected movement of the tool measuring instrument.

[0043] S3, remove the probe from the tool measuring instrument and place it in the CNC machine tool tool magazine, and enter the corresponding installation dimension parameters in the CNC system tool list;

[0044] S4, start the CNC machine tool, the CNC machine tool executes the command, brings up the probe and orients the spindle, and the rotary axis returns to the zero position;

[0045] S5 moves the probe according to the standard commands of the CNC machine tool, and uses the distal and proximal ends of the probe to touch and measure the same detection point (a fixed point at any position on the machine tool), measuring the constant error ΔQ at the distal and proximal ends; the two detection results should be the same. However, since the probe is installed on the probe head, there will be an installation error, which is fixed after installation, so the error value must be measured the first time.

[0046] S6 inputs the constant error ΔQ into the NC measurement program, and obtains the actual accuracy of the machine tool and the zero-point positioning accuracy of the rotary axis based on the constant error ΔQ. After obtaining the constant error in the first measurement, if there is a problem with the machined part or the machine tool is involved in a collision and the accuracy needs to be checked, the same test point is measured again, and the result of the measurement is the error.

[0047] Furthermore, the results of steps S5 and S6 are saved for the purpose of ensuring accuracy traceability and observing the trend of machine tool accuracy changes.

[0048] Example 3

[0049] This embodiment discloses a method for rapid and automatic accuracy detection of CNC machine tools. As a preferred implementation of this technical solution, it includes the following steps:

[0050] S1. Mount the probe onto the clamping mechanism of the tool measuring instrument and assemble a probe on the probe. The length of the probe S≥100mm. The proximal end of the probe is the end closest to the probe transmitter and uses a metal threaded connector to trigger the probe. The distal end of the probe uses a ruby ​​ball head.

[0051] S2. Using a tool measuring instrument, obtain the installation dimension parameters of the probe and stylus, and adjust the coaxiality of the probe and stylus with the tool shaft. The installation dimension parameters include the total length of the probe and stylus, the radius of the ruby ​​ball head of the stylus, and the coaxiality of the stylus with the tool holder. The method for adjusting the coaxiality of the probe and stylus is as follows: rotate the clamping mechanism of the tool measuring instrument, and adjust the coaxiality of the probe and stylus with the tool holder to a range of 0.01mm based on the reading of the change in the projected movement of the tool measuring instrument.

[0052] S3, remove the probe from the tool measuring instrument and place it in the CNC machine tool tool magazine, and enter the corresponding installation dimension parameters in the CNC system tool list;

[0053] S4, start the CNC machine tool, the CNC machine tool executes the command, brings up the probe and orients the spindle, and the rotary axis returns to the zero position;

[0054] S5 moves the probe by standard CNC machine tool commands, and uses the distal and proximal ends of the probe to touch and measure the same detection point, measuring the constant error ΔQ between the distal and proximal ends;

[0055] S6. In S6, the constant error ΔQ is introduced into the NC measurement program to obtain the actual accuracy of the machine tool and the zero-point positioning accuracy of the rotary axis based on the constant error ΔQ. The method for obtaining the zero-point positioning accuracy of the rotary axis is as follows: the probe is moved by the standard CNC machine tool command, and the same detection point is measured again by the far end and the near end of the probe. The measured values ​​P1 and P2 at the far end and the near end are recorded. The difference between P1 and P2 minus ΔQ is the zero-point positioning accuracy of the rotary axis.

[0056] Example 5

[0057] This embodiment discloses a method for rapid and automatic accuracy detection of CNC machine tools. As a preferred implementation of this technical solution, it includes the following steps:

[0058] S1. Mount the probe onto the clamping mechanism of the tool measuring instrument and assemble a probe on the probe. The length of the probe S≥100mm. The proximal end of the probe is the end closest to the probe transmitter and uses a metal threaded connector to trigger the probe. The distal end of the probe uses a ruby ​​ball head.

[0059] S2. Using a tool measuring instrument, the installation dimensions of the probe and stylus are obtained, and the coaxiality of the probe and stylus with the tool shaft is adjusted. These installation dimensions include the total length of the probe and stylus, the radius of the stylus's ruby ​​ball tip, and the coaxiality of the stylus with the tool holder. The tool measuring instrument is a standard optical imaging instrument. It emits a parallel light beam onto the tool, projecting it onto an optical sensor. The tool length and radius are calculated from the projection. By rotating the clamping mechanism of the measuring instrument, if the coaxiality is not zero, the projection will move, thus determining the coaxiality error. The method for adjusting the coaxiality of the probe and stylus is as follows: the probe has screws for adjusting coaxiality. By rotating the clamping mechanism of the tool measuring instrument, the coaxiality of the probe and stylus with the tool holder is adjusted to within 0.01 mm based on the reading of the change in the projection movement of the tool measuring instrument.

[0060] S3, remove the probe from the tool measuring instrument and place it in the CNC machine tool tool magazine, and enter the corresponding installation dimension parameters (probe length and radius) in the CNC system tool list.

[0061] S4, start the CNC machine tool, the CNC machine tool executes the command, brings up the probe and orients the spindle, and the rotary axis returns to the zero position;

[0062] S5 moves the probe head according to the standard instructions of the CNC machine tool, and uses the distal and proximal ends of the probe head to touch and measure the same detection point, and measures the constant error ΔQ at the distal and proximal ends; the constant error ΔQ includes the error value ΔY1 in the Y-axis direction and the error value ΔX1 in the X-axis direction measured by the distal and proximal ends of the probe head.

[0063] The method to obtain ΔY1 is as follows: find a specific point in the Y / Z plane of the machine tool table, and use the far end and near end of the probe to complete the measurement work in the Y / Z plane, and record the measurement difference ΔY1 between the two measurement results.

[0064] The method for obtaining ΔX1 is as follows: find a specific point in the X / Z plane of the machine tool worktable, and use the far end and near end of the probe to complete the measurement work in the X / Z plane, and record the measurement difference ΔX1 between the two measurement results.

[0065] S6 inputs the constant error ΔQ into the NC measurement program, and obtains the actual machine tool accuracy and the zero-point positioning accuracy of the rotary axis based on the constant error ΔQ. Specifically:

[0066] ΔY = YP1 - YP2 - ΔY1, where ΔY is the actual error of the zero point positioning of the rotation axis; YP1 is the measured value of the far end of the probe; YP2 is the measured value of the near end of the probe; ΔY1 is the error value of the probe at the far and near ends of the probe in the Y-axis direction obtained during the first calibration.

[0067] ΔX = XP1 - XP2 - ΔX1, where ΔX: the parallelism error between the main axis and the Z-axis in the X direction; XP1 is the measurement value at the far end of the probe; XP2 is the measurement value at the near end of the probe; ΔX1 is the error value of the probe at the far and near ends in the X-axis direction obtained during the first calibration of the probe.

[0068] Furthermore, an alarm will be triggered if the difference exceeds the threshold in the NC measurement program.

[0069] Example 6

[0070] Step 1, calibrate the probe. Use a standard tool measuring instrument to check the error between the center of the probe and the center of the tool holder, and adjust the coaxiality of the probe and the tool holder to within 0.005mm. Alternatively, you can use another method: mount the probe on the spindle, use a dial indicator to check the error between the center of the probe and the center of the tool holder, and adjust the difference to <0.01mm.

[0071] Step 2: Find a specific point in the Y / Z plane of the workbench, and use the two endpoints of the probe to complete the measurement in the Y / Z plane, while recording the difference between the two measurements ΔY1.

[0072] Step 3: Subtract ΔY1 from the programmed probe, i.e., subtract the probe error, to make it equal to the actual positioning error value of the rotating shaft; Steps 2 and 3 are combined. Figure 3 The principle formula is as follows:

[0073] ΔY = YP1 - YP2 - ΔY1; ΔY is the actual error of the zero point positioning of the rotation axis; YP1 is the measured value of the far end of the probe; YP2 is the measured value of the near end of the probe; ΔY1 is the error value of the probe at the far and near ends of the probe in the Y-axis direction obtained during the first calibration.

[0074] Step 4: Find a specific point in the X / Z plane of the workbench, and use the ruby ​​ball head at the far end of the probe and the metal threaded connector at the near end to complete the measurement work in the X / Z plane at both ends, and record the difference between the two measurements ΔX1.

[0075] Step 5: Subtract ΔX1 from the programmed probe, i.e., subtract the probe error, to make it equal to the error values ​​of the spindle axis and Z-axis in the X / Z plane; then:

[0076] ΔX = XP1 - XP2 - ΔX1; ΔX is the error in the X-direction of the parallelism between the main axis and the Z-axis; XP1 is the measured value at the far end of the probe; XP2 is the measured value at the near end of the probe; ΔX1 is the error value of the probe at the far and near ends in the X-axis direction obtained during the first calibration of the probe.

Claims

1. A method for rapid and automatic detection of the accuracy of CNC machine tools, characterized in that, Using a single probe to check the accuracy of CNC machine tools includes the following steps: S1, Install the probe on the clamping mechanism of the tool measuring instrument, and assemble the probe stylus on the probe; S2. Using a tool measuring instrument, obtain the installation dimension parameters of the probe and stylus, and adjust the coaxiality of the probe and stylus with the tool shaft; S3, remove the probe from the tool measuring instrument and place it in the CNC machine tool tool magazine, and enter the corresponding installation dimension parameters in the CNC system tool list; S4, start the CNC machine tool, the CNC machine tool executes the command, brings up the probe and orients the spindle, and the rotary axis returns to the zero position; S5 moves the probe head according to the standard instructions of the CNC machine tool, and uses the distal and proximal ends of the probe head to touch and measure the same detection point, and measures the constant error ΔQ at the distal and proximal ends; the constant error ΔQ includes the error value ΔY1 in the Y-axis direction and the error value ΔX1 in the X-axis direction measured by the distal and proximal ends of the probe head. The method to obtain ΔY1 is as follows: find a specific point in the Y / Z plane of the machine tool table, and use the far end and near end of the probe to complete the measurement work in the Y / Z plane, and record the measurement difference ΔY1 between the two measurement results. The method for obtaining ΔX1 is as follows: find a specific point in the X / Z plane of the machine tool worktable, and use the far end and near end of the probe to complete the measurement work in the X / Z plane, and record the measurement difference ΔX1 between the two measurement results. S6. Obtain the actual accuracy of the machine tool and the zero-point positioning accuracy of the rotary axis based on the constant error ΔQ. Specifically, the constant error ΔQ is substituted into the NC measurement program to calculate the actual accuracy of the machine tool. The method for obtaining the zero-point positioning accuracy of the rotary axis is as follows: the probe is moved by the standard command of the CNC machine tool, and the same detection point is measured again by the far end and near end of the probe. The measured values ​​P1 and P2 at the far end and near end are recorded. The difference between P1 and P2 minus ΔQ is the zero-point positioning accuracy of the rotary axis.

2. The method for rapid and automatic detection of CNC machine tool accuracy as described in claim 1, characterized in that: In step S1, the length of the probe S is greater than or equal to 100 mm.

3. The method for rapid and automatic detection of CNC machine tool accuracy as described in claim 1, characterized in that: In step S5, the proximal end of the probe, which is near the probe transmitter, uses a metal threaded connector to trigger the probe; the distal end of the probe uses a ruby ​​ball head.

4. The method for rapid and automatic detection of CNC machine tool accuracy as described in claim 1, characterized in that: In step S2, the installation dimension parameters include the total length of the probe and stylus, the radius of the ruby ​​ball head of the stylus, and the coaxiality of the stylus and the tool holder.

5. The method for rapid and automatic detection of CNC machine tool accuracy as described in claim 4, characterized in that, In step S3, the method for adjusting the coaxiality of the probe and stylus is as follows: rotate the clamping mechanism of the tool measuring instrument, and adjust the coaxiality of the probe and stylus with the tool holder to within 0.01mm based on the reading of the change in the projected movement of the tool measuring instrument.

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