Method for on-machine measurement technology application for three-axis machine tools

Abstract

The application discloses a method for applying on-machine measurement technology to a three-axis machine tool. The steps include: 1) supporting incoming detection, calculating Z-direction height difference, and judging whether the incoming detection requirement is met; 2) supporting edge searching and centering detection, including rectangular centering, L-shaped centering, U-shaped centering and circular centering, and avoiding manual dialing centering; and 3) supporting measurement compensation machining detection, including plane measurement compensation, circular compensation and two-point distance compensation, and avoiding secondary clamping of a workpiece and improving machining efficiency.

Description

Technical Field

[0001] This invention belongs to the field of machining and relates to in-machine measurement technology for three-axis machine tools, specifically an in-machine measurement technology application method that combines measurement and machining compensation. Background Technology

[0002] With the continuous upgrading of manufacturing technology, higher demands are being placed on product precision and production efficiency. To address issues such as dimensional deviations, deformation, secondary clamping, and origin errors during product processing, certain inspection methods must be introduced. However, processes such as workpiece alignment, incoming material inspection, in-process inspection, and first-piece inspection involve significant manual intervention, sometimes even involving operators modifying processing programs on-site, directly increasing product processing costs and personnel burden. This is especially true in automated production processes, where it greatly reduces production continuity.

[0003] In-machine measurement technology is a technique for automatically detecting the quality of workpieces on a machining center. This technology can be used for part alignment, workpiece contour and surface deformation compensation, and in-machine inspection during the machining process, thereby improving machining efficiency, reducing error accumulation, and improving machining quality.

[0004] Current in-machine measurement and inspection applications involve a high degree of manual intervention. Inspection programs need to be manually written on the machine tool, and NC programs need to be integrated according to the machining process flow, requiring operators to have a high level of technical skill. Before machining, the workpiece center needs to be located on the coordinate measuring machine. If the machined product is unqualified, it needs to be redone or the machining path modified for rework, resulting in long auxiliary processing times. These problems frequently interrupt processing, making it impossible to guarantee production continuity and hindering further improvements in processing efficiency. Furthermore, incompatibility between equipment can also cause some interference in production. Summary of the Invention

[0005] The purpose of this invention is to address the problems in the prior art by creatively applying in-machine measurement technology to automated machining processes. It provides a method for three-axis machine tool incoming material inspection, automatic centering and alignment inspection, and workpiece plane (inclined surface) measurement and rework based on in-machine measurement technology. Through simple interactive operation, measurement paths are directly generated in CAM software, avoiding on-machine operation. Multiple strategies are used to achieve workpiece incoming material inspection and machine tool workpiece positioning alignment. It enables plane measurement and rework of already machined paths, circular rework (holes, shafts), and two-point distance rework (bosses and grooves). Deviations detected by measurement are compensated into tool parameters, and the machining program is invoked to perform conditional cyclic rework on the workpiece. It supports burr detection and tolerance judgment during contact, and executes corresponding operations based on the judgment results. NC programs can be directly output for machine operation. It automatically judges whether the workpiece's Z-axis height difference exceeds the tolerance, and automatically determines whether to compensate at multiple workpiece origins based on the detection results, applying this compensation to subsequent measurement or machining paths. It eliminates the need for manual on-machine alignment, reducing auxiliary time.

[0006] To achieve the above objectives, the technical solution adopted by the present invention includes the following steps.

[0007] 1. Create incoming material inspection path 1) Establish an incoming material inspection path based on the workpiece's characteristics to be processed, and create measurement points along the path. The number of measurement points is [number missing]. n , ; 2) Set the upper limit of the deviation detection threshold. Lower limit Generate the path and output the CNC program; 3) After the machine tool performs the detection, calculate the height difference in the Z direction based on the theoretical measurement point and the actual measurement point. ; 4) If If the incoming material passes inspection, proceed with subsequent operations; otherwise, trigger an alarm and stop the program.

[0008] 2. Create a center detection path 1) Select the centering deviation detection path type (L-shaped centering, U-shaped centering, rectangular centering, circular centering) according to the workpiece's characteristics to be measured, create the centering detection path, and create measurement points in the path; L-shaped centering: The center coordinates of the workpiece are determined by probing two mutually perpendicular sides within the workpiece surface. The side parallel to the X-axis determines the center Y-coordinate, and the side parallel to the Y-axis determines the center X-coordinate. Three measurement points need to be created: two measurement points on the long side to determine the deflection angle, and one measurement point on the short side. It also supports adding a Z-axis measurement point to determine the center Z-coordinate. U-shaped centering: The center coordinates of the workpiece are determined by probing three U-shaped edges within the workpiece surface. Two of the edges must be parallel. One edge is projected onto the opposite edge, with the projection sharing a common portion with the opposite edge. The edge parallel to the X-axis determines the center Y-coordinate, and the edge parallel to the Y-axis determines the center X-coordinate. Four measurement points need to be created: one for each of the two parallel edges and two for each edge to determine the deflection angle. Adding a Z-axis measurement point is supported to determine the center Z-coordinate. Rectangular Centering: The center coordinates of the workpiece are determined by probing the rectangularly distributed edges within the workpiece surface. The selected edges only need to form a closed rectangle with their extensions. The selected edge is projected onto its opposite edge, and this projection shares a common portion with the opposite edge. The edge parallel to the X-axis determines the center Y-coordinate, and the edge parallel to the Y-axis determines the center X-coordinate. Five measurement points need to be created: two measurement points on the longer side to determine the deflection angle, and one measurement point on each of the remaining three sides. Adding a Z-axis measurement point is supported to determine the center Z-coordinate. Three-point centering of a circle: The center coordinates of the workpiece are determined by probing a circular hole or a cross-section of a cylinder within the workpiece surface. The center coordinates of the workpiece are then fitted based on the measurement points. Three measurement points need to be created, evenly distributed around the circumference. Adding Z-axis measurement points is also supported. Circular four-point centering: The center coordinates of the workpiece are determined by probing a circular hole or a cross-section circle on the workpiece surface. The center coordinates of the workpiece are then fitted based on the measurement points. Four measurement points need to be created, one on each of the positive and negative directions of the machining coordinate axes. Adding Z-axis measurement points is also supported. All detection path types support adding machining allowance to any detection edge and compensating the workpiece origin to the machine tool machining coordinate system; 2) Set the centering compensation threshold Generate the path and output the CNC program; 3) After the machine tool performs the detection, the center deviation is calculated by comparing the theoretical center position with the actual center position of the measured point. ; 4 If , , If both conditions are met, the machine tool machining coordinate system origin compensation will be performed automatically; otherwise, the program will stop. 5) Machine tool machining coordinate system origin compensation: First, calculate the compensation value of the workpiece origin: Then calculate the actual value of the workpiece origin for compensation: The original origin value of the machine tool machining coordinate system is replaced with the sum of the actual value and the compensation value. 6) When creating the centering detection path, select the features of the workpiece model to arrange the measurement points, and add the current machining allowance of the workpiece to meet the centering and alignment requirements of the workpiece.

[0009] 3. Create a compensation processing path 1) In the workpiece model, establish a compensation machining path based on the workpiece's features to be machined, and create measurement points in the path; 2) Set the upper limit of the processing compensation threshold. and lower limit Generate the path and output the CNC program; 3) After the workpiece is machined, a probe is performed on the machine tool. Based on the theoretical data and the actual measured data, the single-point deviation in the Z-direction of the plane is calculated. The deviation is calculated by subtraction. ; 4) If not satisfied If the error occurs, the program will stop and an alarm will be triggered; otherwise, the compensation deviation will be calculated. The deviation value is compensated to the tool parameters, and the machining program is called. 5) After completing the supplementary processing, repeat steps 3) and 4) until any supplementary processing termination condition (number of cycles, processing compensation threshold) is met. Then, exit the supplementary processing cycle and execute an alarm or other specified commands. In step 1) of the compensation machining path, the compensation machining path includes planar measurement compensation, two-point distance compensation, and circular compensation: Planar measurement compensation determines whether the plane machining is qualified by measuring the plane's dimensions relative to the theoretical plane; two-point distance compensation determines whether the machining is qualified by measuring the distance between two points on the workpiece; circular compensation determines whether the machining is qualified by creating three measurement points on the cylindrical or circular hole feature section of the workpiece and comparing the deviation between the theoretical value and the measured value. All three compensation methods mentioned above support cyclic detection and can be configured to execute instructions after exceeding the number of compensation cycles, thus ending processing paths where compensation is ineffective.

[0010] In step 4) of the machining path compensation process, the calculation method for the compensation deviation is selected based on the machining datum. If the bottom surface of the workpiece or the fixture surface is used as the datum, the compensation deviation is calculated as follows: ; If the machined surface of the workpiece is used as the reference, the compensation deviation is calculated as follows: .

[0011] Compared with the prior art, the present invention has the following advantages: Advantage 1: This invention supports incoming material inspection and workpiece clamping angle detection to determine whether the height difference in the Z direction exceeds the tolerance. Advantage 2: This invention combines machine measurement technology with automated production to achieve edge-finding and centering detection of workpieces, supporting rectangular centering, L-shaped centering, U-shaped centering and circular centering of workpieces, and compensating the workpiece origin based on the centering results; Advantage 3: This invention supports the creation of measurement-compensated machining paths and NC program output functions, realizing planar measurement compensation, circular compensation and two-point distance compensation for the machined path, adding the compensation deviation detected by measurement to the corresponding tool radius or tool length, calling the machining program, and performing conditional cyclical compensation machining; Advantage 4: This invention reduces the degree of manual intervention, transferring all work to the programming end, ensuring uninterrupted machine tool operation, and improving machine tool utilization and product processing efficiency. Attached Figure Description

[0012] Figure 1 This invention is based on an application flowchart of in-machine measurement technology; Figure 2 Diagram showing the selection of detection path type; Figure 3. Schematic diagram of incoming material inspection measurement points; Figure 4. Schematic diagram of centering and alignment measurement points; Figure 5. Schematic diagram of measurement points for supplementary processing. Detailed Implementation

[0013] The present invention will now be described in further detail with reference to the accompanying drawings. The overall flowchart is shown below. Figure 1 .

[0014] 1. See Figure 2 Add a detection path type.

[0015] 2. Refer to Figure 3 to create the incoming material inspection path: 1) Select the right side of the rectangular part as the workpiece feature surface for incoming material inspection, create appropriate measurement points on the feature surface, and set the upper limit of the deviation detection threshold. and lower limit Generate the path and output the CNC program; 2) After the machine tool performs the detection, calculate the height difference in the Z direction based on the theoretical measurement point and the actual measurement point. ; 3) If If the incoming material passes inspection, proceed with subsequent operations; otherwise, trigger an alarm and stop the program.

[0016] 3. Referring to Figure 4, create a center detection path: 1) Select the centering deviation detection path type (L-shaped centering, U-shaped centering, rectangular centering, circular centering) and choose rectangular centering to create a centering detection path; 2) Select the four sides of the rectangle to determine the center coordinates of the workpiece, create 5 measurement points, 2 measurement points on the long side to determine the deflection angle, and 1 measurement point on each of the other 3 sides; 3) Set the centering compensation threshold Generate the path and output the CNC program; 4) After the machine tool performs the detection, the center deviation is calculated by comparing the theoretical center position with the actual center position of the measured point. ; 5) If , , If both conditions are met, then perform coordinate system origin compensation for machine tool processing; otherwise, stop the program. 6) Machine tool machining coordinate system origin compensation: First, calculate the compensation value of the workpiece origin. Then calculate the actual value of the workpiece origin for compensation: The original origin value of the machine tool machining coordinate system is replaced with the sum of the actual value and the compensation value.

[0017] 4. Refer to Figure 5 to create a compensation processing path: 1) Select the planar measurement compensation type according to the processing path; 2) Set the upper limit of the processing compensation threshold. and lower limit Calculate the single-point deviation in the Z-direction of the plane with the bottom surface of the workpiece as the reference. Then, the deviation is calculated by subtraction, and the deviation is... ; 3) Determine if the deviation exceeds the set threshold. If not... If the error occurs, the program will stop and an alarm will be triggered; otherwise, a supplementary processing procedure will be executed. 4) Obtain the compensation deviation through deviation calculation. The deviation value is compensated to the tool parameters, and the machining path is used for supplementary machining. After machining is completed, machining deviation is checked again. If the machining standard is met, the supplementary machining cycle is exited; if the number of supplementary machining cycles or the machining compensation threshold is reached, an alarm is triggered and the program is terminated.

Claims

1. A method for applying in-machine measurement technology to a three-axis machine tool, characterized in that, Includes the following steps: 1) In the workpiece model, establish an incoming material inspection path based on the workpiece's features to be processed, and create measurement points along the path, with the number of measurement points being n. Set the upper limit of the deviation detection threshold. Lower limit Generate the path and output the CNC program; After the machine tool performs the detection, it calculates the height difference in the Z direction based on the theoretical and actual measurement points. ; like If the incoming material passes inspection, proceed with the next steps; otherwise, an alarm will sound and the program will stop. 2) In the workpiece model, establish a centering detection path based on the workpiece's features to be measured, create measurement points along the path, and set the centering compensation threshold. Generate the path and output the CNC program; After the machine tool performs the detection, the center deviation is calculated based on the theoretical and actual center positions of the measurement points. ,like , , If both conditions are met, the machine tool machining coordinate system origin compensation will be performed automatically; otherwise, the program will stop. For coordinate system origin compensation in machine tool processing, first calculate the compensation value for the workpiece origin: Then calculate the actual value of the workpiece origin for compensation: The original origin value of the machine tool machining coordinate system is replaced with the sum of the actual value and the compensation value. 3) In the workpiece model, establish a measurement compensation path based on the workpiece's features to be processed, create measurement points in the path, and set the upper limit of the processing compensation threshold. and lower limit Generate the path and output the CNC program; After the workpiece is machined, a probe is performed on the machine tool. Based on theoretical data and actual measured data, the single-point deviation in the Z-direction of the plane is calculated. The deviation is calculated by subtraction. ; If not satisfied If the error occurs, the program will stop and an alarm will be triggered; otherwise, the compensation deviation will be calculated. The deviation value is compensated to the tool parameters, the supplementary machining program is called, and the machining deviation is detected again. If the compensation threshold or the number of machining operations is reached, the supplementary machining cycle is exited and an alarm or other specified commands are executed. The calculation method for compensation deviation is selected based on the machining datum. If the bottom surface of the workpiece or the fixture surface is used as the datum, then the compensation deviation is calculated. ; If the machined surface of the workpiece is used as the reference, then the compensation deviation is calculated as follows: .

2. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 2) supports centering deviation detection in L-shaped splitting. The center coordinates of the workpiece are determined by detecting the two mutually perpendicular sides in the workpiece surface. Three measurement points need to be created for L-shaped splitting: two measurement points on the long side and one measurement point on the short side. 1) The side parallel to the X-axis determines the Y-coordinate of the center, and the side parallel to the Y-axis determines the X-coordinate of the center; 2) Determine the deflection angle using two measurement points along the longer side; 3) Supports adding Z-axis measurement points to determine the center Z-coordinate; 4) Supports adding machining allowance to any detection edge and compensating the workpiece origin to the machine tool machining coordinate system.

3. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 2) supports centering deviation detection in U-shaped splitting. The center coordinates of the workpiece are determined by detecting the three U-shaped sides in the workpiece surface. Four measurement points need to be created for U-shaped splitting: one measurement point for each of the two parallel sides and two measurement points for each side. 1) Two of the sides are required to be parallel. Project one of the sides onto the opposite side, and the projection and the opposite side have a common part. 2) The side parallel to the X-axis determines the center Y-coordinate, and the side parallel to the Y-axis determines the center X-coordinate; 3) Determine the deflection angle using two measurement points on one side; 4) Supports adding Z-axis measurement points to determine the center Z-coordinate; 5) Supports adding machining allowance to any detection edge and compensating the workpiece origin to the machine tool machining coordinate system.

4. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 2) supports centering deviation detection in rectangular division. By probing the rectangularly distributed edges within the workpiece surface, the center coordinates of the workpiece are determined. Five measurement points need to be created for rectangular division: two measurement points on the longer side and one measurement point on each of the other three sides. 1) The selected detection edge only needs to satisfy the condition that its extension can form a closed rectangle. The selected edge is required to be projected onto its opposite edge, and this projection has a common part with the opposite edge. 2) The side parallel to the X-axis determines the center Y-coordinate, and the side parallel to the Y-axis determines the center X-coordinate; 3) Determine the deflection angle using two measurement points along the longer side; 4) Supports adding Z-axis measurement points to determine the center Z-coordinate; 5) Supports adding machining allowance to any detection edge and compensating the workpiece origin to the machine tool machining coordinate system.

5. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 2) supports centering deviation detection in three-point circular division. The center coordinates of the workpiece are determined by probing a circular hole or a cross-sectional circle on a cylinder within the workpiece surface. Three measurement points need to be created for three-point circular division, with three measurement points evenly distributed on the circumference. 1) Fit the workpiece center coordinates based on the measurement points; 2) Supports adding Z-axis measurement points; 3) Supports adding machining allowances at the detection edge and compensating the workpiece origin to the machine tool machining coordinate system.

6. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 2) supports centering deviation detection in circular four-point division. The center coordinates of the workpiece are determined by probing a circular hole or cross-section circle on a cylinder within the workpiece surface. Four measurement points need to be created for circular four-point division, one measurement point in each of the positive and negative directions of the machining coordinate axis on the circumference. 1) Fit the workpiece center coordinates based on the measurement points; 2) Supports adding Z-axis measurement points; 3) Supports adding machining allowances at the detection edge and compensating the workpiece origin to the machine tool machining coordinate system.

7. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 3) supports plane measurement compensation, which determines whether the plane machining is qualified by measuring the plane's dimensions relative to the theoretical plane. 1) Supports cyclic probing; 2) Supports setting an instruction to terminate processing paths where compensation is ineffective after exceeding the number of compensation cycles.

8. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 3) supports two-point distance compensation, which determines whether the processing is qualified by measuring the distance between two points on the workpiece; 1) Supports cyclic probing; 2) Supports setting an instruction to terminate processing paths where compensation is ineffective after exceeding the number of compensation cycles.

9. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: Step 3) supports circular compensation, which involves creating three measurement points on the cylindrical or circular hole feature section of the workpiece and judging whether the machining is qualified by comparing the deviation between the theoretical value and the measured value. 1) Supports cyclic probing; 2) Supports setting an instruction to terminate processing paths where compensation is ineffective after exceeding the number of compensation cycles.

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