Machining accuracy detection method for CNC five-axis machine tools

Abstract

The present invention discloses a method for detecting machining accuracy of a CNC five-axis machine tool, comprising the following steps: designing a machining test piece; designing the detection elements of the test piece; designing the main detection dimensions of the test piece, including: precision boring a positioning center hole so that the positioning center hole serves as a reference A-hole for other detection elements; sequentially milling the four sides of the test piece with the same tool and the same cutting parameters; boring four blind holes for measurement on the four vertical sides with the same tool and the same cutting parameters; machining the upper end face of the test piece with the same tool and cutting parameters as those used for machining the four sides; and detecting and judging: after machining is completed, detecting whether the size and position requirements on the test piece meet the design requirements. The accuracy detection method of the present invention can comprehensively and effectively detect the five-axis directional machining accuracy of the machine tool, effectively solving the problem that high-precision five-axis machine tools that have passed the acceptance inspection according to the existing CNC five-axis machine tool inspection standards still cannot meet the machining accuracy requirements of the precision casing of new aircraft engines.

Description

Technical Field

[0001] The present invention relates to the field of precision detection of numerically controlled five-axis machine tools, and in particular to a method for detecting machining precision of numerically controlled five-axis machine tools. Background Art

[0002] In existing technologies, the precision testing of five-axis machine tools has formed mature international standards and processes. The testing process is as follows:

[0003] 1. First, test the geometric accuracy of the machine tool in accordance with the international standard ISO10791-1, mainly to determine the accuracy of the machine tool structure, which is the premise and basis of the machine tool accuracy;

[0004] 2. According to the international standard VDI / DGQ3441, use a laser interferometer to test the positioning accuracy and repeatability of each axis to determine the operating accuracy of the machine tool;

[0005] 3. According to the international standard ISO10791-7, test cutting of M test blocks in the three-axis state, the roughness, roundness, angle, size and other indicators of the machined surface are tested to detect the dynamic accuracy of the machine tool;

[0006] 4. According to the international standard ISO10791-7, cut the "S" type specimen under the five-axis linkage state to test the comprehensive accuracy of the machine tool under the multi-axis linkage state. The contour accuracy of the "S" type specimen is required to be no more than 0.12.

[0007] This standard precision testing method has certain limitations when processing high-precision spatial orientation dimensions of aircraft engines relative to multiple different benchmarks. Although the "S"-shaped test piece is used to test the comprehensive accuracy of the machine tool's multi-axis linkage state, it cannot accurately reflect the errors of the machine tool in multi-axis and directional processing at different angles. As a result, in the field of high-precision aircraft engine processing, even if the five-axis machine tool has passed the international standard precision test, it is still unable to process high-precision aircraft engine components.

[0008] The existing patent CN114063559A "A method for verifying the accuracy of five-axis CNC machine tools" is a combination of the detection methods in items 3 and 4 above, and does not clearly define the error offset of the five-axis machine tool during spindle orientation angle processing. Summary of the Invention

[0009] The present invention provides a method for detecting the machining accuracy of a CNC five-axis machine tool to solve the technical problem that existing methods cannot accurately reflect the errors of the machine tool in directional machining of multiple axes and at different angles, resulting in the inability of five-axis machine tools to process high-precision aerospace engine components even though they have passed the international standard accuracy test in the field of high-precision machining of aerospace engines.

[0010] The technical solution adopted in the present invention is as follows:

[0011] A method for detecting machining accuracy of a CNC five-axis machine tool comprises the following steps: S10: designing a machining test piece: designing a square-shaped test piece, and making the center of the upper end surface of the test piece have an inward-concave positioning center hole; S20: designing the detection elements of the test piece: fixing the test piece on a machine tool workbench or a fixture, and aligning the positioning center hole, straightening the front face of the test piece as the C reference surface, and aligning the bottom face of the test piece as the B reference surface; S30: designing the main detection dimensions of the test piece, specifically comprising the following steps: S301: precision boring the positioning center hole to make the positioning center hole The center hole is the reference A hole for other inspection elements; S302: Use the same tool and the same cutting parameters to mill the four sides of the test piece in sequence; S303: Use the same tool and the same cutting parameters to bore four measuring blind holes on the four vertical sides; S304: Use the same tool and cutting parameters as those used for machining the four sides to machine the upper end face of the test piece; S40: Inspection and judgment: After machining is completed, check whether the size and position requirements on the test piece meet the design requirements. If they meet the requirements, it means that the CNC five-axis machine tool meets the use requirements.

[0012] Furthermore, in step S10, correspondingly arranged and inwardly concave mounting grooves are provided on both side surfaces of the test piece to fix the test piece on a machine tool workbench or a fixture.

[0013] Furthermore, the CNC five-axis machine tool is an AB cradle-type double-turntable horizontal five-axis machine tool.

[0014] Furthermore, use a micrometer to rotate the B axis to align the center hole and make its runout no more than 0.003mm; straighten the C reference plane to no more than 0.003mm, and use the C reference plane as the angular reference, and set the B axis of the workpiece coordinate system to 0 degrees; align the B reference plane to no more than 0.003mm.

[0015] Furthermore, step S301 specifically includes the following steps: rotating the machine tool A axis to a -90° state, and running a five-axis directional machining instruction; and precision boring the positioning center hole to ensure that the roundness of the positioning center hole is no greater than 0.003 mm.

[0016] Furthermore, step S302 specifically includes the following steps: rotating the machine tool A-axis to the 0° state, and running the five-axis directional machining instruction; taking the positioning center hole as the rotation center, setting the theoretical lengths of milling two adjacent surfaces as L1 and L2 in the CNC program; using the bottom blade of the milling cutter to rough mill and fine mill the four surrounding sides of the specimen respectively; measuring the actual distances from L1 and L2 to the positioning center hole as L1±X5 and L2±X6, where X5 and X6 are the measured error values.

[0017] Furthermore, step S303 specifically includes the following steps: rotating the machine tool A-axis to the 0° state, and running the five-axis directional machining instruction; fine boring four measuring blind holes ΦE, ΦD, ΦC, and ΦF at the same height h3 on the four sides of the test piece, first machining ΦE at the C reference plane using the B0 directional machining method, and then machining three holes of the same size ΦD, ΦC, and ΦF at B90°, B180°, and B270° respectively; detecting whether the coaxiality of the ΦC hole to the ΦE hole is greater than ΦX2, whether the coaxiality of the ΦD hole to the ΦF hole is greater than ΦX3, and whether the position of the D hole relative to the A, B, and C references is greater than ΦX4.

[0018] Furthermore, step S304 specifically includes the following steps: rotating the A-axis to -90° and running the five-axis directional machining instruction; using the bottom blade of the same milling cutter and the same cutting parameters as those used to process L1 and L2 in step S302 to process the upper end face of the test piece according to the designed h4 size requirements; measuring the error value of h4 and determining the error value from the center of rotation of the equipment A-axis in the Y direction to the work table.

[0019] The present invention has the following beneficial effects:

[0020] The CNC five-axis machine tool processing accuracy detection method of the present invention adds a detection method for spatial angle directional processing accuracy on the basis of the existing CNC five-axis machine tool detection standard, which can comprehensively and effectively detect the five-axis directional processing accuracy of the machine tool, and further improve the detection of the high-precision directional processing accuracy of the five-axis machine tool; it effectively solves the problem that high-precision five-axis machine tools that have passed the acceptance inspection according to the existing CNC five-axis machine tool detection standard still cannot meet the processing accuracy requirements of the precision casing of the new aircraft engine; the detection method of the present invention is simple and easy to operate, and provides a reference for the precision calibration of the five-axis machine tool; during the detection operation, the invention provides a "rectangular parallelepiped" test piece that can correctly reflect the accuracy of multi-axis directional processing, and describes the multi-axis spatial directional processing method and detection method of the test piece in detail. The detection result effectively reflects the deviation values ​​of X, Y, and Z of the five-axis machine tool relative to the rotation center at different angles of the A and B axes, which is a supplement and improvement to the five-axis machine tool accuracy detection standard applied in the field of high-precision processing of aircraft engines.

[0021] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of the top view of the test piece before processing in a preferred embodiment of the present invention;

[0024] Figure 2 yes Figure 1 A schematic diagram of a sectional main structure;

[0025] Figure 3 This is a schematic diagram of the test piece detection dimensions of a preferred embodiment of the present invention;

[0026] Figure 4 yes Figure 3 A schematic diagram of a sectional main structure;

[0027] Figure 5 This is a schematic diagram of the test piece processing dimensions of a preferred embodiment of the present invention;

[0028] Figure 6 yes Figure 5 Schematic diagram of the sectional main view structure.

[0029] Legend

[0030] 10. Test piece; 101. Positioning center hole; 102. Mounting groove; DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0032] Reference Figure 1-Figure 4 The preferred embodiment of the present invention provides a method for detecting machining accuracy of a CNC five-axis machine tool, comprising the following steps:

[0033] S10: Designing and processing the test piece 10: Designing a square-shaped test piece 10, and making the center of the upper end surface of the test piece 10 have an inwardly concave positioning center hole 101;

[0034] S20: Design the test elements of the test piece 10: Fix the test piece 10 on the machine tool workbench or fixture, align and locate the center hole 101, straighten the front surface of the test piece 10 as the C reference surface, and align the bottom surface of the test piece 10 as the B reference surface;

[0035] S30: Design the main test dimensions of the test piece 10, specifically including the following steps:

[0036] S301: precision boring the positioning center hole 101 so that the positioning center hole 101 serves as the reference A hole for other inspection elements;

[0037] S302: Milling the four sides of the specimen 10 in sequence using the same tool and the same cutting parameters;

[0038] S303: Boring four measuring blind holes on four vertical sides using the same tool and cutting parameters;

[0039] S304: machining the upper end surface of the specimen 10 using the same tool and cutting parameters as those used for machining the four sides;

[0040] S40: Detection and judgment: After the processing is completed, the size and position requirements on the test piece 10 are checked according to the design requirements to see if they meet the requirements. If they do, it means that the CNC five-axis machine tool meets the use requirements.

[0041] When the CNC five-axis machine tool machining accuracy detection method of the present invention is used, in the step of "milling the four sides of the test piece 10 in sequence with the same tool and the same cutting parameters", when the CNC five-axis machine tool is an AB cradle-type double-turntable horizontal five-axis machine tool, and the C reference plane is the B-axis 0°, then the distance error from the four sides to the positioning center hole 101 can represent the error value of the machine tool spindle Z-axis direction, the error value of the machine tool in the X-axis direction and the Z-axis direction, and the indexing error of the B-axis rotation based on the B-axis rotation center; in the step of "boring four measuring blind holes on the four vertical sides with the same tool and the same cutting parameters", when the CNC five-axis machine tool is an AB cradle-type double-turntable horizontal five-axis machine tool, and the C reference plane is the B-axis 0°, then the distance error from the four sides to the positioning center hole 101 can represent the error value of the machine tool spindle Z-axis direction, the error value of the machine tool in the X-axis direction and the Z-axis direction, and the indexing error of the B-axis rotation based on the B-axis rotation center; When the CNC five-axis machine tool is an AB cradle-type double-turntable horizontal five-axis machine tool, the coaxiality error of the four measuring blind holes and the errors relative to the references A, B, and C can represent the offset error of the machine tool in the X-axis and Z-axis directions with the B-axis rotation center, the comprehensive offset error in the X-axis and Z-axis directions, the B-axis rotation indexing error, the Y-axis workpiece zero point setting error, etc.; in the step "using the same tool and cutting parameters as the four sides to process the upper end face of the specimen 10", when the CNC five-axis machine tool is an AB cradle-type double-turntable horizontal five-axis machine tool, the height error value is used to judge the error value from the A-axis rotation center of the equipment to the work table in the Y direction.

[0042] The CNC five-axis machine tool processing accuracy detection method of the present invention adds a detection method for spatial angle directional processing accuracy on the basis of the existing CNC five-axis machine tool detection standard, which can comprehensively and effectively detect the five-axis directional processing accuracy of the machine tool, and further improve the detection of the high-precision directional processing accuracy of the five-axis machine tool; it effectively solves the problem that the high-precision five-axis machine tool that has passed the acceptance inspection according to the existing CNC five-axis machine tool detection standard still cannot meet the precision processing requirements of the precision casing of the new aircraft engine; the detection method of the present invention is simple and easy to operate, and provides a reference for the precision calibration of the five-axis machine tool; during the detection operation, the invention provides a "rectangular parallelepiped" specimen 10 that can correctly reflect the precision of multi-axis directional processing, and describes the multi-axis spatial directional processing method and detection method of the specimen in detail. The detection result effectively reflects the deviation values ​​of X, Y, and Z of the five-axis machine tool relative to the rotation center at different angles of the A and B axes, which is a supplement and improvement to the five-axis machine tool precision detection standard applied in the field of high-precision processing of aircraft engines.

[0043] Alternatively, as Figure 2As shown, in step S10, corresponding concave mounting grooves 102 are provided on both sides of the test piece 10 to fix the test piece 10 on the machine tool workbench or fixture. Figure 2 As shown, the two mounting grooves 102 are symmetrically arranged with respect to the positioning center hole 101 of the test piece 10, thereby improving the accuracy of the test piece.

[0044] Optionally, in the present invention, the CNC five-axis machine tool is an AB cradle type double-turntable horizontal five-axis machine tool for the following specific description. The AB cradle type double-turntable horizontal five-axis machine tool has three linear axes X, Y, and Z and two rotation axes A and B.

[0045] Optionally, step S20 specifically includes the following steps:

[0046] Use a dial indicator to rotate the B axis to align and locate the center hole 101, and make the runout no greater than 0.003mm;

[0047] Drag the C reference plane to a straight position of no more than 0.003mm, use the C reference plane as the angular reference, and set the B axis of the workpiece coordinate system to 0 degrees;

[0048] The difference between the B reference plane and the reference plane should not exceed 0.003mm.

[0049] Alternatively, as Figure 3 and Figure 4 As shown, step S301 specifically includes the following steps:

[0050] Rotate the machine tool A axis to -90° and run the five-axis directional machining command;

[0051] The positioning center hole 101 is precision bored to ensure that the roundness of the positioning center hole 101 is not greater than 0.003 mm.

[0052] Alternatively, as Figure 3 and Figure 4 As shown, step S302 specifically includes the following steps:

[0053] Rotate the machine tool A axis to 0° and run the five-axis directional machining command;

[0054] With the positioning center hole 101 as the rotation center, the theoretical lengths of milling two adjacent surfaces are set as L1 and L2 in the NC program;

[0055] The four sides of the periphery of the test piece 10 are rough milled and fine milled respectively using the bottom edge of the milling cutter;

[0056] The actual distances from L1 and L2 to the positioning center hole 101 are measured to be L1±X5 and L2±X6, where X5 and X6 are the measured error values.

[0057] Specifically, rotate the A-axis of the machine tool to the 0° state. Since the datum A is processed at the -90° state of the A-axis, the dimensional elements processed at the 0° state all include the A-axis rotation error. During processing, with the positioning center hole 101 as the rotation center, run the five-axis directional processing instructions, set the theoretical lengths of the two adjacent sides of the milling block to L1 and L2 in the CNC program, and use the bottom edge of the milling cutter to rough mill and fine mill the four sides of the specimen respectively. Due to certain errors in the machine tool, the actual distances from L1 and L2 to the positioning center hole 101 are measured to be L1±X5 and L2±X6, as shown in the figure. Figure 3 As shown in the figure, X5 and X6 are the measured error values. When the C reference plane is used as the B-axis 0°, X6 represents the error value of the machine tool spindle in the Z-axis direction and the indexing error of the B-axis rotation, based on the B-axis rotation center. X5 represents the error value of the machine tool in the X-axis and Z-axis directions and the indexing error of the B-axis rotation, based on the B-axis rotation center.

[0058] When this step is actually processed, Figure 5 and Figure 6 As shown, the four sides of the block are milled using the bottom edge of the milling cutter, and the dimensions from the center of the positioning hole 101 to both sides of the block are 180±0.015.

[0059] Alternatively, as Figure 3 and Figure 4 As shown, step S303 specifically includes the following steps:

[0060] Rotate the machine tool A axis to 0° and run the five-axis directional machining command;

[0061] Four blind holes (ΦE, ΦD, ΦC, and ΦF) are finely bored on the four sides of the specimen 10 at the same height h3. ΦE is first machined at the C reference plane using the B0 directional machining method, and then three holes of the same size (ΦD, ΦC, and ΦF) are machined at B90°, B180°, and B270°, respectively.

[0062] Check whether the coaxiality of ΦC hole to ΦE hole is greater than ΦX2, whether the coaxiality of ΦD hole to ΦF hole is greater than ΦX3, and whether the position of D hole relative to A, B, and C references is greater than ΦX4.

[0063] Specifically, the machine tool's A-axis was rotated to 0°. Since datum A was machined at -90° on the A-axis, the dimensional features machined at 0° all include the A-axis rotation error. Five-axis directional machining instructions were run to fine-bored four holes (ΦE, ΦD, ΦC, and ΦF) at the same height h3 on all four sides of the specimen. ΦE was first machined at the C datum plane using the B0 directional machining method, and then the three holes of the same size (ΦD, ΦC, and ΦF) were machined at B90°, B180°, and B270°, respectively. The coaxiality of the ΦC hole with the ΦE hole was no greater than ΦX2, the coaxiality of the ΦD hole with the ΦF hole was no greater than ΦX3, and the position accuracy of the D hole relative to the A, B, and C datums was no greater than ΦX4.

[0064] Among them, X2 represents the offset error of the machine tool in the X-axis direction, the B-axis rotation indexing error, and the Y-axis workpiece zero point setting error with the B-axis rotation center; X3 represents the offset error of the machine tool in the X-axis and Z-axis directions, the B-axis rotation indexing error, and the Y-axis workpiece zero point setting error with the B-axis rotation center; X4 represents the comprehensive offset error of the machine tool in the X-axis and Z-axis directions, the B-axis rotation indexing error, and the Y-axis workpiece zero point setting error with the B-axis rotation center; the Y-axis workpiece zero point setting error can be detected by actual value on the machine tool.

[0065] When this step is actually processed, Figure 5 and Figure 6 As shown, a hole with a diameter of Φ25mm and a depth of 30mm is bored on each of the four sides of the block. The position error of the D reference hole relative to the A, B, and C references is no more than 0.03mm, and the coaxiality error of the other two holes is no more than 0.02mm.

[0066] Alternatively, as Figure 3 and Figure 4 As shown, step S304 specifically includes the following steps:

[0067] Rotate the A-axis to -90° and run the five-axis orientation machining command;

[0068] The upper end surface of the test piece 10 is machined according to the designed size requirement of h4 using the bottom edge of the same milling cutter used to machine L1 and L2 in step S302 and the same cutting parameters;

[0069] Measure the error value of h4 to determine the error value from the center of rotation of the A-axis of the equipment to the work surface in the Y direction.

[0070] When this step is actually processed, Figure 5 and Figure 6 As shown, the bottom edge of the same milling cutter with a size of 180±0.015 is processed in step S302 and the upper end face of the part is processed with the same cutting parameters to ensure a size of 60±0.015.

[0071] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for detecting machining accuracy of a CNC five-axis machine tool, characterized in that: The following steps are involved: S10: Designing and processing a test piece (10): Designing a square-shaped test piece (10), and making the center of the upper end surface of the test piece (10) have an inwardly concave positioning center hole (101); S20: Design the test elements of the test piece (10): fix the test piece (10) on the machine tool workbench or fixture, and align the center hole (101), straighten the front surface of the test piece (10) as the C reference surface, and align the bottom surface of the test piece (10) as the B reference surface; S30: Design the main test dimensions of the test piece (10), specifically including the following steps: S301: precision boring the positioning center hole (101) so that the positioning center hole (101) serves as a reference A hole for other inspection elements; S302: Milling the four sides of the test piece (10) in sequence with the same tool and the same cutting parameters; specifically, rotating the A axis of the machine tool to 0° and running the five-axis directional machining instruction; taking the positioning center hole (101) as the rotation center, setting the theoretical lengths of milling two adjacent sides as L1 and L2 in the CNC program; using the bottom edge of the milling cutter to rough mill and fine mill the four sides of the test piece (10) respectively; measuring the actual distances from L1 and L2 to the positioning center hole (101) as L1±X5 and L2±X6, where X5 and X6 are the measured error values; S303: Boring four measuring blind holes on four vertical sides with the same tool and the same cutting parameters; specifically including: rotating the machine tool A axis to 0° and running the five-axis directional machining instruction; fine boring the four measuring blind holes ΦE, ΦD, ΦC, and ΦF at the same height h3 on the four sides of the test piece (10); first machining ΦE at the C reference plane using the B0 directional machining method, and then machining the three holes of the same size ΦD, ΦC, and ΦF at B90°, B180°, and B270° respectively; checking whether the coaxiality of the ΦC hole to the ΦE hole is greater than ΦX2, whether the coaxiality of the ΦD hole to the ΦF hole is greater than ΦX3, and whether the position of the D hole relative to the A, B, and C references is greater than ΦX4; S304: The upper end surface of the specimen (10) is machined using the same tool and cutting parameters as those used for machining the four sides; S40: Detection and judgment: After the processing is completed, the size and position requirements on the test piece (10) are checked according to the design requirements to see if they meet the requirements. If they meet the requirements, it means that the CNC five-axis machine tool meets the use requirements; The CNC five-axis machine tool is an AB cradle type double-turntable horizontal five-axis machine tool.

2. The CNC five-axis machine tool machining accuracy detection method according to claim 1, characterized in that: In step S10, correspondingly arranged and inwardly concave mounting grooves (102) are further provided on both side surfaces of the test piece (10) for fixing the test piece (10) on a machine tool workbench or a fixture.

3. The method for detecting machining accuracy of a CNC five-axis machine tool according to claim 1, wherein: Step S20 specifically includes the following steps: Use a micrometer to rotate the B axis to align the center hole (101) and make the runout no greater than 0.003mm; Drag the C reference plane to a straight position of no more than 0.003mm, use the C reference plane as the angular reference, and set the B axis of the workpiece coordinate system to 0 degrees; The difference between the B reference plane and the reference plane should not exceed 0.003mm.

4. The method for detecting machining accuracy of a CNC five-axis machine tool according to claim 1, wherein: Step S301 specifically includes the following steps: Rotate the machine tool A axis to -90° and run the five-axis directional machining command; The positioning center hole (101) is precision bored to ensure that the roundness of the positioning center hole (101) is not greater than 0.003 mm.

5. The method for detecting machining accuracy of a CNC five-axis machine tool according to claim 1, wherein: Step S304 specifically The following steps are involved: Rotate the A-axis to -90° and run the five-axis orientation machining command; The upper end surface of the test piece (10) is machined using the bottom edge of the same milling cutter used to machine L1 and L2 in step S302 and the same cutting parameters, and is machined according to the designed size requirement of h4; Measure the error value of h4 to determine the error value from the center of rotation of the A-axis of the equipment to the work surface in the Y direction.

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