Automatic error-proofing control method for tool length compensation of CNC machining center

Abstract

The present application relates to the technical field of numerical control machining, and especially relates to an automatic error-proof control method for tool length compensation of a CNC machining center. The method comprises the establishment and configuration of a tool data source; a post-processing software generates an embedded verification logic macro program ecNC program, the verification logic macro program is embedded with a hierarchically set allowable deviation threshold and a theoretical standard length of a tool; the NC program with the nested verification logic macro program is imported into a CNC system and started; the macro program is automatically called after the tool changing instruction of the NC program is executed by the machine tool end, and a current tool measured length compensation value collected by the CNC system is read; the verification logic macro program automatically calculates a tool length deviation value, compares the value with a preset allowable deviation threshold bound to the tool, and executes corresponding instructions; after the tool length compensation exception is excluded, the CNC system is reset, and the machining is restarted. The present application realizes full-process data linkage error-proofing, hierarchical tolerance control, and automatic verification, alarm and program execution.

Description

Technical Field

[0001] This invention relates to the field of CNC machining technology, and in particular to an automatic error prevention control method for tool length compensation in CNC machining centers. Background Technology

[0002] Computer Numerical Control (CNC) machining centers, also known as CNC machine tools with tool magazines and automatic tool changers, rely heavily on tool length compensation as a core parameter to ensure machining depth and dimensional accuracy during the machining of precision parts. In actual production, errors in tool length compensation, such as improper tool clamping, incorrect data entry of the tool setter, or incorrect use of other tool compensation parameters, can all contribute to quality issues. Therefore, error-proofing measures are necessary to control tool length compensation errors and minimize the resulting malfunctions.

[0003] Currently, existing error prevention methods mainly include manual verification and machine tool self-verification, but both methods have obvious shortcomings.

[0004] Manual verification: Relying on operators to manually compare the tool length value after tool change, the probability of human error is high. In large-scale continuous processing scenarios, it is very easy to miss the detection, and errors are unavoidable.

[0005] Machine tool built-in calibration: This function has limitations. Some CNC systems only support single fixed tolerance calibration and cannot set deviation thresholds according to tool type, machining process, and accuracy level. In addition, because the program and machine tool data are separated, the post-processing of the programming software and the machine tool compensation data are independent of each other and lack linkage and verification. As a result, the post-output program cannot automatically carry the theoretical standard length of the tool, and the machine tool cannot automatically compare the theoretical value with the measured compensation value. When a length compensation deviation occurs, it only provides a simple prompt and cannot automatically pause or terminate the program, which can easily lead to problems such as overcutting, part scrapping, spindle collision, and tooling fixture damage.

[0006] In conclusion, the existing technology has obvious inconveniences and defects in practical use, and it is necessary to improve it. Summary of the Invention

[0007] To address the aforementioned shortcomings, this invention provides an automatic error-proofing control method for tool length compensation in CNC machining centers, thereby resolving issues such as verification errors, functional limitations, and data inconsistencies that exist in manual verification and machine tool-integrated verification.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: An automatic error-proofing control method for tool length compensation in a CNC machining center includes the following steps: S1. Establish tool data source and configure it to the post-processing software at the process end and the CNC system at the machine tool end respectively; S2. The post-processing software generates the NC program. The NC program has a built-in verification logic macro program, which embeds the allowable deviation threshold and the theoretical standard length of the tool in a graded setting. S3. Import the NC program containing the nested verification logic macro program into the CNC system and start it; S4. After the machine tool executes the tool change command of the NC program, it automatically calls the macro program and reads the current measured tool length compensation value collected by the CNC system. S5. The verification logic macro program automatically calculates the tool length deviation value; S6. Compare the calculated length deviation value with the preset allowable deviation threshold of the tool binding, and execute the corresponding command. S7. After eliminating the tool length compensation anomaly, reset the CNC system and restart machining.

[0009] Furthermore, in S1, on the process side: a standardized tool list is compiled in the tool room, and a unique theoretical standard length is set for each tool; the theoretical standard lengths of all tools and the allowable deviation thresholds set in stages are pre-entered into the configuration file of the post-processing software on the process side. Machine tool end: Use a tool setter to measure each tool and collect the measured length compensation value of each tool; enter the measured length compensation value into the CNC system and store it.

[0010] Furthermore, the criteria for differentiating the permissible deviation thresholds in the tiered settings are as follows: The tool deviation threshold for finishing is ≤0.02mm; The deviation threshold for semi-finishing tools is 0.02–0.05 mm; The roughing tool deviation threshold is 0.05–0.1 mm.

[0011] Furthermore, S2 includes the following steps: S21. The process end completes the NC program in the programming software and selects the tool number required for this machining process according to the machining procedure. S22. When the post-processing software outputs the NC program, it automatically identifies all the tool numbers selected in the NC program and retrieves the theoretical standard length and preset allowable deviation threshold of the corresponding tool from the configuration file. The allowable deviation threshold is set according to the tool type, machining process, and machining accuracy level, and is bound to the tool number and stored in the configuration file of the post-processing software. S23. The post-processing software automatically nests the verification logic macro program used for tool length verification into the output NC program, and the verification logic macro program is associated with the tool change command one by one.

[0012] Furthermore, in S3, the NC program is transmitted to the CNC system via a CF card, USB data cable, or DNC network.

[0013] Furthermore, S4 includes: S41, The CNC system executes the tool change command in the NC program, the tool magazine completes automatic tool change and the spindle locks the tool; S42. Automatically triggers the execution of the verification logic macro program; S43. The verification logic macro program uses the currently running tool number as the retrieval index to call the tool management module built into the CNC system to obtain the tool magazine tool position number corresponding to the tool. S44. The verification logic macro program uses the tool magazine tool position number and compensation sequence number as indexes to read the measured length compensation value of the tool stored in the CNC system.

[0014] Furthermore, in S5, the calculation process for the tool length deviation value is as follows: Length deviation value = |Measured length compensation value − Theoretical standard length|.

[0015] Furthermore, in S6, When the length deviation value is less than or equal to the allowable deviation threshold, the tool length compensation status is determined to be normal, the verification logic macro program ends, and the machine tool continues to execute the subsequent cutting instructions of the NC program. When the length deviation value exceeds the allowable deviation threshold, the tool length compensation is determined to be abnormal, and the verification logic macro program executes three levels of handling actions in sequence.

[0016] Furthermore, when the tool length compensation is abnormal, the three-level handling action executed by the verification logic macro program is as follows: Alarm: Triggers the built-in alarm command of the CNC system, and a modal alarm pop-up window appears on the human-machine interface, displaying a prompt message that the current tool length is incorrect; Pause: The machine tool pauses the execution of the current NC program, and the machine tool's motion axes and spindle stop moving; Termination: Forcefully terminates the currently running NC program on the machine tool.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The automatic error-proofing control method for tool length compensation in CNC machining centers of this invention can achieve full-process data linkage error prevention. It combines tool chamber tool setting data, post-programming software, and CNC machine tool data at three levels. The post-programming software automatically carries the theoretical standard length of the tool, and the machine tool automatically compares the measured compensation value. No manual recording or verification is required, eliminating the risk of dimensional scrap and tool collision caused by human error. Unlike traditional single fixed tolerance verification, this invention adopts hierarchical tolerance precision control. Deviation thresholds can be set according to roughing / semi-finishing / finishing and tool type differences. While meeting the requirements of precision dimensional control, it can achieve high-efficiency machining. After tool change, automatic verification is performed. When the length compensation exceeds the standard, an automatic pop-up alarm, machine stop, and program termination are triggered to prevent abnormal cutting and significantly reduce the scrap loss of tools, fixtures, and workpieces. Detailed Implementation

[0018] The technical solution of the present invention will be further described in a non-limiting manner below with reference to specific embodiments.

[0019] An automatic error-proofing control method for tool length compensation in a CNC machining center according to an embodiment of the present invention includes the following steps: S1. Establish tool data source and configure it to the post-processing software at the process end and the CNC system at the machine tool end respectively.

[0020] Specifically, on the process side: a standardized tool list is compiled in the tool room, and a unique theoretical standard length is set for each tool; the theoretical standard lengths of all tools and the allowable deviation thresholds set by level are pre-entered into the configuration file of the post-processing software on the process side, so as to realize the one-to-one binding and storage of tool number and theoretical standard length.

[0021] The permissible deviation thresholds for the different grades are as follows: deviation threshold for finishing tools ≤ 0.02mm, deviation threshold for semi-finishing tools 0.02~0.05mm, and deviation threshold for roughing tools 0.05~0.1mm; carbide end mills, drills, taps, and boring tools are each configured with their own independent deviation thresholds.

[0022] The configuration file of the post-processing software supports batch import and batch modification of the theoretical standard length and allowable deviation threshold of the tool. When adding a new tool, the binding relationship is automatically generated, eliminating the need to repeatedly edit the macro program.

[0023] Machine tool end: A dedicated tool setting instrument in the tool room is used to measure each tool and collect the measured length compensation value of each tool; the measured length compensation value is entered into the tool address bar of the CNC system on the machine tool end and stored in the length compensation variable dedicated to the corresponding tool number.

[0024] The measured length compensation value can be entered manually or in batches.

[0025] S2. The post-processing software generates the NC program, which contains a built-in verification logic macro program. The verification logic macro program embeds the permissible deviation threshold and the theoretical standard length of the tool, which are set in stages.

[0026] Specifically: S21, the process end completes the NC program in the programming software and selects the tool number required for this machining process according to the machining procedure; S22. When the post-processing software outputs the NC program, it automatically identifies all the tool numbers selected in the NC program and retrieves the theoretical standard length and preset allowable deviation threshold of the corresponding tool from the configuration file. The allowable deviation threshold is set according to the tool type, machining process, and machining accuracy level, and is bound to the tool number and stored in the configuration file of the post-processing software. S23. The post-processing software automatically nests the verification logic macro program used for tool length verification into the output NC program. The verification logic macro program is associated with the tool change command one by one, and is preferably embedded after each tool change command. The verification logic macro program has built-in assignable variables: theoretical standard length, allowable deviation threshold, machine tool measured length reading instruction, deviation calculation instruction, threshold comparison instruction, and abnormal handling instruction; Tool data for tools not selected in this machining process will not be written into the current NC program, thus simplifying the program size and reducing the computational load on the machine tool.

[0027] In S23, the verification logic macro program is a general macro code for machine tool systems, compatible with FANUC macro programs and Siemens R parameter macro programs, and can be adapted to mainstream vertical, horizontal, and five-axis CNC machining centers on the market.

[0028] S3. Import the NC program containing the nested verification logic macro program into the CNC system and start it.

[0029] The NC program containing the nested verification logic macro program can be transferred to the CNC system using any of the following methods: CF card, USB data cable, or DNC network transmission.

[0030] Load the target NC program into the human-machine interface of the CNC system, press the cycle start button, and the machine tool will automatically execute the instructions of the NC program segment by segment.

[0031] S4. After the machine tool executes the tool change command of the NC program, it automatically calls the macro program to read the current measured tool length compensation value collected by the CNC system.

[0032] S4 includes the following sub-steps: S41. The CNC system on the machine tool executes the tool change command in the NC program, the tool magazine completes automatic tool change, and the spindle locks the tool. S42. Automatically triggers the execution of the verification logic macro program; S43. The verification logic macro program uses the currently running tool number as the retrieval index to call the tool management module built into the CNC system to obtain the tool magazine tool position number corresponding to the tool. S44. The verification logic macro program uses the tool magazine tool position number and compensation sequence number as indexes to read the measured length compensation value of the tool stored in the CNC system.

[0033] Taking the Siemens 840D SL system as an example, the tool length compensation parameters are read through the CNC system variable $TC_DP3.

[0034] S5. The verification logic macro program automatically calculates the tool length deviation value.

[0035] The calculation process is as follows: The verification logic macro program retrieves the theoretical standard length preset in the NC program and the measured length compensation value collected by the CNC system, and calculates the length deviation value according to the following formula: Length deviation value = |Measured length compensation value − Theoretical standard length|.

[0036] S6. Compare the calculated length deviation value with the preset allowable deviation threshold of the tool binding, and execute the corresponding instruction.

[0037] When the length deviation value is less than or equal to the allowable deviation threshold, the tool length compensation status is determined to be normal, the verification logic macro program ends, and the machine tool continues to execute the subsequent cutting instructions of the NC program. When the length deviation value exceeds the allowable deviation threshold, the tool length compensation is determined to be abnormal, and the verification logic macro program executes three levels of handling actions in sequence: Alarm: Triggers the built-in alarm command of the CNC system, and a modal alarm pop-up window appears on the human-machine interface. The pop-up window displays the prompt information of the current tool length error (abnormal tool number, actual length, theoretical standard length, deviation value, and over-standard prompt text).

[0038] Pause: The machine tool pauses the execution of the current NC program, and the machine tool's motion axes and spindle stop moving; Termination: Forcefully terminates the currently running NC program on the machine tool. Locks the machining process, preventing operators from continuing to initiate cutting.

[0039] S7. After eliminating the tool length compensation anomaly, reset the CNC system and restart machining.

[0040] Read the alarm information from the human-machine interface and troubleshoot the fault accordingly: re-clamp the tool, re-measure and update the tool length compensation value in the machine tool using the tool setter, and verify the matching relationship between the program tool number and the tool magazine tool; after the fault is completely eliminated, operate the machine tool to reset the CNC system, reload the NC program, and press the cycle start button to resume machining.

[0041] Normal processing scenario: S1. Establish tool data source and complete dual-end configuration.

[0042] The tool room compiles a complete list of machining tools. T01 is for finishing a φ6 end mill with a theoretical standard length of 120.000mm and a finishing allowable deviation threshold of 0.02mm. T03 is for roughing a φ10 end mill with a theoretical standard length of 125.000mm and a roughing allowable deviation threshold of 0.08mm. The tool numbers, theoretical lengths, and deviation thresholds of the two sets are entered into the UG post-processing configuration file to bind T01 and T03 with the corresponding parameters.

[0043] The measured length compensation values ​​of T01 and T03 were measured using an optical tool setter. The measured compensation value of T01 was 120.010 mm and the measured compensation value of T03 was 125.060 mm. The two sets of values ​​were then imported into the Siemens 840D sl system and stored in the system variable $TC_DP3 corresponding to the tool addresses of T01 and T03.

[0044] S2. Program the automatic embedding of verification logic macros after programming.

[0045] Write a part machining program in UG and use two tools, T01 and T03, to complete the machining.

[0046] The post-processing software identifies the program tool numbers T01 and T03 and automatically retrieves the bound theoretical length and deviation threshold.

[0047] The Siemens R parameter verification logic macro program is automatically nested after each M06 tool change instruction. The verification logic macro program has the following built-in variables: R1 = theoretical standard length, R2 = allowable deviation threshold, R3 = machine tool read measured length, R4 = length deviation, R5 = comparison judgment instruction, alarm stop instruction.

[0048] Tool data such as T02 and T04 that are not selected by the program are not written into the NC program.

[0049] S3. The NC program is imported into the CNC system on the machine tool and run. The NC program is transmitted to the CNC system via the DNC network. The operator loads the program and presses the cycle start button.

[0050] S4. Automatically read the measured length compensation value after tool change. The machine tool executes M06 T01 tool change, the spindle locks tool T01, and automatically executes the embedded verification logic macro program; the verification logic macro program searches the tool magazine for tool position T01 and reads the measured length compensation value R3=120.010mm in $TC_DP3.

[0051] S5. Automatically calculate the length deviation value R4=|R3-R1|=|120.010-120.000|=0.010mm.

[0052] S6. Compare the calculated length deviation value with the preset allowable deviation threshold bound to the tool. The preset T01 finishing threshold R2 = 0.02mm, 0.010 ≤ 0.02, indicating that the tool length compensation is normal, the verification logic macro program ends, and the machine tool executes T01 cutting. After machining, execute M06 T03 tool change, call the verification logic macro program again to read the measured value of T03, 125.060mm, calculate the deviation as 0.06mm, which is less than the roughing threshold of 0.08mm, and the machining is normal.

[0053] Abnormal failure scenarios: Similar to normal machining scenarios, a tool clamping error was simulated: the actual length compensation value of the T01 finishing tool was entered as 120.035mm.

[0054] Steps S1-S4 are the same as the normal machining scenario described above. After tool change T01, the measured length compensation value R3 = 120.035mm is read.

[0055] S5. Automatically calculate the length deviation value: R4=|R3-R1|=|120.035-120.000|=0.035mm.

[0056] S6 compares the calculated length deviation value with the preset allowable deviation threshold for the tool. The preset T01 finishing threshold R2 = 0.02mm; 0.035 > 0.02, indicating an abnormal tool length compensation. A red modal alarm window popped up on the machine tool's human-machine interface, displaying: "T01 tool length compensation exceeds the standard. Theoretical length is 120.000mm, actual length is 120.035mm, deviation is 0.035mm, allowable deviation is 0.02mm." The machine tool's moving axes and spindle stop moving; The CNC system forcibly terminates the current NC program, preventing further cutting.

[0057] The operator checked the alarm information, reassembled the T01 tool, retested and updated the compensation value to 120.010mm using the tool setter, performed a reset operation, reloaded the program and started machining. After the verification was passed, the machine operated normally.

[0058] The above description is an explanation of the present invention and not a limitation thereof. Within the scope of protection of the present invention, any form of modification or equivalent substitution may be made. The scope of the present invention is defined in the claims.

Claims

1. An automatic error-proofing control method for tool length compensation in a CNC machining center, characterized in that, Includes the following steps: S1. Establish tool data source and configure it to the post-processing software at the process end and the CNC system at the machine tool end respectively; S2. The post-processing software generates the NC program. The NC program has a built-in verification logic macro program, which embeds the allowable deviation threshold and the theoretical standard length of the tool in a graded setting. S3. Import the NC program containing the nested verification logic macro program into the CNC system and start it; S4. After the machine tool executes the tool change command of the NC program, it automatically calls the macro program and reads the current measured tool length compensation value collected by the CNC system. S5. The verification logic macro program automatically calculates the tool length deviation value; S6. Compare the calculated length deviation value with the preset allowable deviation threshold of the tool binding, and execute the corresponding command. S7. After eliminating the tool length compensation anomaly, reset the CNC system and restart machining.

2. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 1, characterized in that, In S1, the process end: compiles a standardized tool list in the tool room, independently sets a unique corresponding theoretical standard length for each tool; and pre-enters the theoretical standard lengths of all tools and the allowable deviation thresholds set in stages into the configuration file of the post-processing software of the process end. At the machine tool end: a tool setter is used to measure each tool and collect the measured length compensation value of each tool; the measured length compensation value is entered into the CNC system and stored.

3. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 2, characterized in that, The criterion for distinguishing the allowable deviation thresholds in the graded settings is as follows: The tool deviation threshold for finishing is ≤0.02mm; The deviation threshold for semi-finishing tools is 0.02–0.05 mm; The roughing tool deviation threshold is 0.05–0.1 mm.

4. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 1, characterized in that, S2 includes the following steps: S21. The process end completes the NC program in the programming software and selects the tool number required for this machining process according to the machining procedure. S22. When the post-processing software outputs the NC program, it automatically identifies all the tool numbers selected in the NC program and retrieves the theoretical standard length and preset allowable deviation threshold of the corresponding tool from the configuration file. The allowable deviation threshold is set according to the tool type, machining process, and machining accuracy level, and is bound to the tool number and stored in the configuration file of the post-processing software. S23. The post-processing software automatically nests the verification logic macro program used for tool length verification into the output NC program, and the verification logic macro program is associated with the tool change command one by one.

5. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 1, characterized in that, In S3, the NC program is transmitted to the CNC system via a CF card, USB data cable, or DNC network.

6. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 1, characterized in that, S4 includes the following steps: S41, The CNC system executes the tool change command in the NC program, the tool magazine completes automatic tool change and the spindle locks the tool; S42. Automatically triggers the execution of the verification logic macro program; S43. The verification logic macro program uses the currently running tool number as the retrieval index to call the tool management module built into the CNC system to obtain the tool magazine tool position number corresponding to the tool. S44. The verification logic macro program uses the tool magazine tool position number and compensation sequence number as indexes to read the measured length compensation value of the tool stored in the CNC system.

7. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 1, characterized in that, In step S5, the calculation process for the tool length deviation is as follows: Length deviation value = |Measured length compensation value − Theoretical standard length|.

8. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 1, characterized in that, In S6: When the length deviation value is less than or equal to the allowable deviation threshold, the tool length compensation status is determined to be normal, the verification logic macro program ends, and the machine tool continues to execute the subsequent cutting instructions of the NC program. When the length deviation value exceeds the allowable deviation threshold, the tool length compensation is determined to be abnormal, and the verification logic macro program executes three levels of handling actions in sequence.

9. The automatic error-proofing control method for tool length compensation in CNC machining centers according to claim 8, characterized in that, When tool length compensation is abnormal, the three-level handling action executed by the verification logic macro program is as follows: Alarm: Triggers the built-in alarm command of the CNC system, and a modal alarm pop-up window appears on the human-machine interface, displaying a prompt message that the current tool length is incorrect; Pause: The machine tool pauses the execution of the current NC program, and the machine tool's motion axes and spindle stop moving; Termination: Forcefully terminates the currently running NC program on the machine tool.