A method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology

Abstract

This invention discloses a method for improving the accuracy of five-axis positioning measurement based on in-machine measurement technology. This method involves creating a common datum and a datum for the measured element on the model to be machined. The common datum and the datum for the measured element are used to construct workpiece position compensation for the measured element. Measurement of the measured element is performed based on this workpiece position compensation, thereby reducing measurement errors caused by combined machine tool errors and improving measurement accuracy. This method can improve the accuracy of five-axis positioning measurement and increase machining yield; it has a wide range of applications, supporting various types of machine tools; it reduces manual intervention and error rates; and it improves user feasibility and standardizes operating procedures.

Description

Technical Field

[0001] This invention belongs to the field of on-machine measurement technology in machining, specifically relating to a method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology. Background Technology

[0002] During the on-machine measurement of parts on a five-axis machine tool, the machine tool turntable has an inherent compound error that cannot be eliminated. Some parts have complex structures and large volumes, and the distance between the reference elements to be measured and the measured elements is large, which leads to the problem of amplified measurement error and reduced measurement accuracy.

[0003] See Figure 1 As shown, a part needs to be tested for the coaxiality of its cylindrical features. The distance between the reference cylinder and the cylinder to be measured is 100mm. Due to the combined error of the turntable, the center position of the second cross-section of the reference cylinder has a deviation of 5μm. When the measuring axis is extended to the cross-section to be measured, it has deviated by 5×100 / 10=50μm. At this time, even if the axis to be measured and the reference axis meet the coaxiality requirement, the coaxiality test result will still have an error of 2×50=100μm.

[0004] Given the above background, there is currently no effective solution to this problem. Summary of the Invention

[0005] This invention addresses the issues described above. It provides a method for improving the accuracy of five-axis positioning measurements based on in-machine measurement technology. This method involves constructing a common reference between the measured elements, and using this common reference for workpiece position compensation, thereby improving measurement accuracy.

[0006] To achieve the above objectives, the technical solution adopted by the present invention includes the following steps: 1. Create a common datum Base and a datum Base1 for the tested element Element1 on the model under test. 1) Base, Base1, and Element1 support point, line, circle, plane, and cylinder elements; 2) Base requires point measurement to be performed in the same coordinate system as Base1 and Element1; 3) Base and Base1 must meet the accuracy requirements of the workpiece itself; 2. Use Base and Base1 to create the workpiece position compensation WPC1 for Element1. 1) The workpiece position status information includes rotation information around the X, Y, and Z axes and X, Y, and Z origin information; 2) Methods for constructing workpiece position compensation include, but are not limited to: surface-line-point method, one-surface-two-circle method, rotating body method, three-surface method, and one-surface-one-groove method; 3. Based on WPC1 conditions, measure Element1 and create the measurement path λ1 for Element1; 4. Repeat steps 1, 2, and 3 above to create the reference base Base2 for the measured element, the workpiece position compensation WPC2, and the measurement path λ2 for the measured element Element2; 5. Select an evaluation method to evaluate the positional tolerances of the measurement paths λ1 and λ2 generated by the measurement elements. Improve measurement accuracy by using a common datum and improve evaluation accuracy by referencing workpiece position compensation, thereby improving the five-axis positioning measurement accuracy. 6. Evaluation methods include distance, angle, parallelism, perpendicularity, and coaxiality.

[0007] Compared with existing technologies, its advantages are: Advantage 1: This invention reduces the impact of the composite error of the machine tool at different positioning positions on the measurement results of the measured element by arranging the reference and the measured element in a common coordinate system, thereby improving the measurement accuracy and increasing the machine tool processing yield. Advantage 2: By referencing a common benchmark, this invention reduces the impact of composite machine tool errors at different positioning positions on the evaluation results between measured elements in five-axis positioning measurement, thereby improving evaluation accuracy and increasing machine tool processing yield. Advantage 3: This invention achieves automated error compensation by using on-machine measurement technology, reducing the rate of manual intervention in five-axis positioning measurement, lowering the error rate, and improving measurement reliability. Attached Figure Description

[0008] Figure 1 A schematic diagram of the product's reference cylinder and the cylinder being measured; Figure 2 This is a flowchart illustrating the method. Figure 3 For the product and its cross-sectional view; Figure 4 This is a schematic diagram of the cylindrical A1 datum plane and the common datum. Figure 5 A schematic diagram of the measurement points on the reference surface for position compensation of cylindrical workpiece A1; Figure 6 A schematic diagram of the measurement point A1 on the cylinder; Figure 7 This is a schematic diagram of the reference plane B1 of the cylinder; Figure 8 A schematic diagram of the measurement points on the reference surface for position compensation of cylindrical workpiece B1; Figure 9 This is a schematic diagram of the measurement point B1 on the cylinder. Detailed Implementation

[0009] This invention discloses a method for improving the accuracy of five-axis positioning measurement based on in-machine measurement technology. Referring to the accompanying drawings, the method involves creating one or more common references and references for the measured elements on the workpiece. Before measurement, the measured elements undergo workpiece position compensation using the common references and the measured element references. Multiple measured elements repeatedly undergo workpiece position compensation using the common references. By utilizing the common references and workpiece position compensation, the accuracy error caused by the combined machine tool errors among the measured elements is reduced, thereby improving measurement accuracy.

[0010] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0011] See Figure 3 As shown, the coaxiality of cylinders A1 and B1 of a certain part needs to be measured. To eliminate the compound error of the five-axis machine tool and improve the measurement accuracy, the measurement method of this invention is used, specifically in the following steps: 1. Select a common reference for the element being measured: See [link / reference] Figure 4 As shown, on the part being measured, features that meet the requirements of the common datum are sought. Plane C and plane D are used as the workpiece's fine grinding surfaces, which have high precision and share a common coordinate system with cylinder A and cylinder B. Therefore, plane C and plane D are selected as the common datum surfaces. 2. Create a common baseline for the elements being tested: See [link / reference] Figure 4 As shown, measurement points are arranged on plane C and plane D respectively. The measurement points are used to generate plane element measurement paths, which are defined as common reference plane C (used as the reference plane of coordinate system YOZ plane) and common reference plane D (used as the reference plane of coordinate system XOZ plane). 3. Create the reference point A2 for cylinder A1: See Figure 4 As shown, plane A2 is the finely ground surface of the workpiece, which has high precision and can be selected as the reference plane. Measurement points are arranged on plane A2, and the plane element measurement path is generated using the measurement points and defined as reference plane A2. 4. Create the workpiece position compensation path β1 for cylinder A1. (See also...) Figure 5 As shown, the workpiece position compensation path is created using the three-plane method. In the three-plane method, the reference planes refer to the common reference plane C and common reference plane D in 2 and the reference plane A2 in 3, respectively. 5. Create the measurement path λ1 for cylinder A1: See [link / reference] Figure 6 As shown, measurement points are arranged on cylinder A1, and measurement paths are generated using the measurement points. The measurement paths reference the workpiece position compensation β1 created in step 4. 6. Create the reference point B2 for cylinder B1: See Figure 7 As shown, plane B2 is the precision-ground surface of the workpiece, possessing high accuracy, and can be selected as the reference plane. Measurement points are arranged on plane B2, and a plane element measurement path is generated using these measurement points, which is defined as reference plane B2. 7. Create the workpiece position compensation path β2 for cylinder B1: See [link / reference] Figure 8 As shown, the three-plane method is used to create the workpiece position compensation path. In the three-plane method, the reference planes refer to the common reference plane C and common reference plane D in 2 and the reference plane B2 in 6, respectively. 8. Create measurement path λ2 for cylinder B1: See Figure 9 As shown, measurement points are arranged on the cylinder B1 to be measured, and the measurement points are used to generate a cylinder measurement path. The measurement path references the workpiece position compensation β2 created in 7. 9. Create Element Evaluation Path: Create a cylinder coaxiality evaluation path. The measured element in the path references measurement path λ1 in 5, and the reference element references measurement path λ2 in 8. Perform path calculation to reduce the accuracy error of cylinders A1 and B1 caused by machine tool composite errors. The accuracy is improved mainly through the following two points: ① By measuring the reference and the measured element in a common coordinate system, the influence of machine tool composite errors on the measurement results of the measured element is reduced, thus improving the measurement accuracy; ② By referencing a common position reference, the influence of machine tool composite errors on the evaluation results between the measured elements is reduced, thus improving the evaluation accuracy.

[0012] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for improving the accuracy of five-axis positioning measurement based on in-machine measurement technology, characterized in that: 1) Create a common datum Base, a datum Base1 for the elements under test, and a datum Base2 for the elements under test on the model under test; 2) Construct the workpiece position compensation WPC1 for the measured element Element1 using the common datum Base and the datum Base1 of the measured element; 3) Construct the workpiece position compensation WPC2 for the measured element Element2 using the common datum Base and the datum Base2 of the measured element; 4) Measure the element Element1 under workpiece position compensation WPC1; 5) Measure the element Element2 under workpiece position compensation WPC2; 6) Evaluate the positional tolerances of the measurement paths λ1 and λ2 generated by the measured elements Element1 and Element2. Improve measurement accuracy by using a common datum and improve evaluation accuracy by referencing workpiece position compensation, thereby improving the five-axis positioning measurement accuracy.

2. The method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology according to claim 1, characterized in that, The common reference Base, the reference Base1 of the element under test, the reference Base2 of the element under test, the element under test Element1, and the element under test Element2 support point, line, circle, plane, and cylinder elements.

3. The method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology according to claim 1, characterized in that, In steps 2) and 3), the common reference Base, the references Base1 and Base2 of the measured elements, and the measured elements Element1 and Element2 are required to be measured in a common coordinate system, wherein Base and Base1 and Base2 meet the accuracy requirements of the workpiece itself.

4. The method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology according to claim 1, characterized in that, In steps 2) and 3), the workpiece position status information contained in WPC1 and WPC2 includes rotation information around the X, Y, and Z axes and X, Y, and Z origin information.

5. The method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology according to claim 4, characterized in that, The methods for constructing workpiece position compensation include, but are not limited to: surface-line-point method, one-surface-two-circle method, rotating body method, three-surface method, and one-surface-one-groove method.

6. The method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology according to claim 1, characterized in that, In steps 4) and 5), measurement paths λ1 and λ2 of the measured elements Element1 and Element2 are created under workpiece position compensation WPC1 and WPC2, respectively.

7. The method for improving the accuracy of five-axis positioning measurement based on on-machine measurement technology according to claim 1, characterized in that, In step 6), select an evaluation method to evaluate the positional tolerances of the paths λ1 and λ2 generated by the measurement elements. The evaluation method supports distance, angle, parallelism, perpendicularity and coaxiality.

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