Value traceability method for involute curve with large base circle radius

Abstract

A value traceability method for an involute curve with a large base circle radius. The method comprises the following steps: step 1, determining a coordinate system for value traceability and value transfer parameters; step 2, adjusting the pose of an involute template (8); step 3, adjusting the position of the involute template (8); step 4, calibrating involute parameters; and step 5, eliminating coordinate system establishment errors to achieve calibration of a measurement instrument. The method fills the gap of value traceability methods for large-size gears with diameters greater than 500 mm, and can effectively identify the impact of coordinate system establishment errors on the accuracy of tooth profile measurement, and improve the applicability of a large-gear measurement instrument (9) in complex environments such as on-machine measurement. The method enables high-precision involute measurement, is simple and easy to implement, offers high measurement accuracy, facilitates transportation and installation adjustments, and has good market application prospects and promotion value.

Description

A method for tracing the value of involute with large base circle radius Technical Field

[0001] The invention belongs to the technical field of gear precision measurement, and in particular relates to a value tracing method for an involute with a large base circle radius. Background Art

[0002] Large gears generally refer to gears with a diameter greater than 500mm, among which gears with a diameter of 500 to 3000mm are called large gears, and gears with a diameter greater than 3000mm are called extra-large gears. Large and extra-large gears are widely used in ships, heavy-load helicopters, new energy equipment and other fields. Compared with general gear transmissions, this type of gear transmission has the characteristics of high power (single-axis 50MW and above), large size (gear diameter 3-5m), large mass (single unit to tens of tons), high gear precision (3-5 levels), long life, and complex structure. However, precise control of tooth surface profile, improvement of manufacturing accuracy, reduction of vibration and noise, and increase of power density all require precise measurement technology for large gears as a guarantee. The key to achieving precise measurement of large gears is to ensure the measurement accuracy of large gear measuring instruments.

[0003] For the calibration of the measurement accuracy of large gear measuring instruments, the tooth profile is generally measured using an involute template calibrated by the National Institute of Metrology. The calibration value of the template's value transfer parameter is compared, and the instrument indication is corrected to achieve traceability of the tooth profile measurement results of the large gear measuring instrument.

[0004] Dalian University of Technology, Kyoto University, and the National Metrology Institute of Japan have developed a dual-roller laser measurement involute reference device based on the pure rolling generation method. This device uses a laser interferometer to directly measure an involute template with a base disk, achieving high-precision involute measurements with U(Fα, fHα, ffα) < 0.5μm. However, this method is limited by the size of the rollers and can only be used for traceability of involute tooth profiles with small and medium base circle parameters of specific specifications. It cannot be used for traceability of large gears with diameters greater than 500mm.

[0005] To achieve traceability of the measurement of involute tooth profiles with large base circle radii, PTB Germany built a 5m×4m×2m three-dimensional coordinate measuring machine, incorporated it into the length traceability chain, and developed a calibration procedure for the 3D measurement of gear templates. This measurement method uses length measurements with multiple laser trackers to obtain spatial position error mapping of the tooth surface probe points for the tooth profile measurement task, achieves error correction for the tooth surface probe points, and provides traceability of the measurement values ​​based on laser frequency calibration. However, the measurement accuracy of this measurement method is limited, and the measurement results have not yet reached the first-level accuracy assessment standard for large involute gears.

[0006] Due to the lack of a measurement traceability method for the involute tooth profile with a large base circle radius, a measurement transfer system for large gears has not yet been established, making it impossible to calibrate the corresponding large gear measuring instruments. As a result, the accuracy of the involute tooth profile measurement results for large-size gears with a diameter greater than 500 mm cannot be verified. Summary of the Invention

[0007] The present invention aims to provide a method for tracing the measurement of an involute with a large base circle radius, so as to overcome the problem that the prior art cannot achieve the measurement tracing of an involute tooth profile with a large base circle radius.

[0008] In order to achieve the purpose of the present invention, the solution provided by the present invention is: a method for tracing the value of an involute with a large base circle radius, comprising the following steps:

[0009] Step 1: Determine the coordinate system and value transfer parameters for value traceability:

[0010] Establish three coordinate systems: the gear workpiece coordinate system, the measurement coordinate system of the large gear measuring instrument, and the design coordinate system of the involute template;

[0011] Determination of measurement transfer parameters: the involute tooth profile cylinder capable of measurement transfer, and the reference surface used for spatial positioning;

[0012] Step 2: Adjust the posture of the involute template:

[0013] Place the involute template together with the six-degree-of-freedom fine-tuning device on the upper end face of the gear to be tested;

[0014] Step 3: Adjust the position of the involute template:

[0015] The probe of the large gear measuring instrument is used to measure the spatial positioning reference surface of the involute template, and the design coordinate system of the involute template is made to coincide with the measurement coordinate system by fine-tuning the six-degree-of-freedom fine-tuning device;

[0016] Step 4: Involute parameter calibration:

[0017] When calibrating the involute parameters, the involute template rotates with the workpiece coordinate system. The gear tooth profile deviation measurement method is used to measure the tooth profile deviation curve of the involute template. If the calibration standard is met, the calibrated large gear measuring instrument can be used to measure the involute tooth profile.

[0018] If the calibration standard is not met, proceed to the next step;

[0019] Step 5: Eliminate coordinate system establishment errors and calibrate measuring instruments:

[0020] By analyzing the tooth profile deviation measurement results F α Identify the coordinate system establishment error (Δx0, Δy0): F α=f(Δx0,Δy0)

[0021] The established coordinate system is corrected so that the measurement coordinate system coincides with the workpiece coordinate system. Then, the third and fourth steps are repeated. After the calibration standard is reached, the involute tooth profile is measured.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] 1. The method provided by the present invention fills the gap in the measurement traceability method for large-sized gears with a diameter greater than 500 mm. In the method of the present invention, the position of the involute template is placed across the workpiece coordinate system and the measurement coordinate system. By measuring the involute template, the influence of the coordinate system establishment error on the tooth profile measurement accuracy can be effectively identified, thereby effectively overcoming the common problems in the high-precision measurement of large gears.

[0024] 2. The method of the present invention can use a template with a radius equal to that of the base circle of the gear being measured to calibrate the measurement system. The calibrated measurement space includes the measurement space of the actual measurement, and can realize "one-to-one" and "point-to-point" calibration and correction of large gear measuring equipment at the production site, thereby improving the applicability of large gear measuring instruments in complex environments such as on-machine measurement.

[0025] 3. The present method ensures the relative positional relationship between the involute tooth surface and the base circle center through measurement and fine-tuning, enabling high-precision measurement of involutes. Due to the method provided by the present invention, the corresponding involute template used is small in size, avoiding the problem of using a large template that is affected by factors such as temperature and gravity, which can affect the template's accuracy and stability, leading to increased uncertainty in the value transfer parameters.

[0026] 4. The measurement method provided by the present invention is simple and easy to implement, with high measurement accuracy. It can effectively meet the calibration of high-precision large gear measuring instruments and the calibration of large gear on-machine measurement systems. It is also easy to transport, install and adjust, and has good market application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic diagram showing the principle of an involute measurement method based on pure rolling generation;

[0028] FIG2 is a schematic diagram of the structure of the involute template used in an embodiment of the present invention;

[0029] FIG3 is an axial side view taken along the direction A of FIG2 ;

[0030] FIG4 is a schematic diagram of the measurement traceability method of the involute tooth profile with a large base circle radius.

[0031] The reference numerals are as follows: 1-involute tooth profile cylinder; 2-reference bottom surface; 3-reference top surface; 4-tooth root reference surface; 5-tooth top reference surface; 6-rotary worktable; 7-measured gear; 8-involute template; 9-large gear measuring instrument; 10-six-degree-of-freedom fine-tuning device. DETAILED DESCRIPTION

[0032] The method of the present invention is described in detail below with reference to the accompanying drawings.

[0033] See Figure 1: This is the principle of the common pure rolling generating method in the prior art. The roller radius is consistent with the base circle radius. When the roller rolls purely on the guide rail, the intersection point P of the standard involute and the generating line (guide rail) remains unchanged. A stylus placed at point P allows involute measurement. However, this method is limited by the size of the roller and can only be used to trace the values ​​of involute tooth profiles with small and medium base circle parameters of specific specifications.

[0034] A method for tracing the value of an involute with a large base circle radius, comprising the following steps:

[0035] Step 1: Determine the coordinate system and value transfer parameters for value traceability:

[0036] When applying the template to calibrate the gear measurement system, the following three coordinate systems need to be involved: the gear workpiece coordinate system, the measurement coordinate system of the large gear measuring instrument 9 and the design coordinate system of the involute template 8.

[0037] Measurement value transfer parameters: Determined to be the involute tooth profile cylinder 1 capable of measurement value transfer, and the reference surface used for spatial positioning, and have the verification value given by the National Metrology Institute.

[0038] According to the above requirements, the structure of the involute template 8 provided in an embodiment of the present invention is as follows: Referring to Figures 1 and 2, it includes two oppositely arranged involute tooth profile cylinders 1 for realizing value transfer, a reference bottom surface 2 and a reference top surface 3 for spatial positioning are symmetrically arranged on the upper and lower sides, and a tooth root reference surface 4 and a tooth top reference surface 5 are parallelly arranged on the front and rear sides, and the involute template 8 has a calibration value of the National Institute of Metrology.

[0039] Step 2: Adjust the posture of the involute template 8:

[0040] Referring to Figure 4 , during measurement, an involute template 8, certified by the National Institute of Metrology and with a verified value, is placed on the upper end face of the gear 7 being measured, along with a six-degree-of-freedom fine-tuning device 10. By adjusting the six-degree-of-freedom fine-tuning device 10, the tooth profile involute template 8 can produce slight rotations in the X, Y, and Z directions, as well as translational motion in the X, Y, and Z directions.

[0041] Step 3: Adjust the position of the involute template 8:

[0042] The probe of the large gear measuring instrument 9 is used to measure the spatial positioning reference surface of the involute template 8, and the design coordinate system of the involute template 8 is made to coincide with the measurement coordinate system by adjusting the six-degree-of-freedom fine-tuning device 10.

[0043] That is, the spatial position of the involute template 8 in the measurement coordinate system is ensured by measuring with the large gear instrument 9. Because the involute template 8 is also actually located on the rotary table 6 and can rotate with the workpiece around the rotation axis, it also exists in the gear workpiece coordinate system. Therefore, the involute template spans both the measurement coordinate system and the gear workpiece coordinate system.

[0044] Step 4: Involute parameter calibration:

[0045] When calibrating the involute parameters, the involute template 8 rotates with the workpiece coordinate system, and the gear tooth profile deviation measurement method is used to measure the tooth profile deviation curve of the involute template 8. If the calibration standard measurement result is consistent with the verification value of the involute template 8, or is within the error allowable range of the large gear measuring instrument 9, the calibrated large gear measuring instrument 9 can be used for involute tooth profile measurement;

[0046] If the calibration standard is not achieved, proceed to the next step.

[0047] Step 5: Eliminate coordinate system establishment errors and calibrate measuring instruments:

[0048] In actual work, the workpiece installation eccentricity and instrument geometric error can be detected by other methods and eliminated or corrected. Then the inconsistent measurement results are mainly caused by the fact that the measurement coordinate system of the measurement system may not coincide with the axis of the rotary table 6. This is also difficult to determine and is common in large gear measuring instruments 9.

[0049] By analyzing the tooth profile deviation measurement results F α Identify the coordinate system establishment error (Δx0, Δy0): F α =f(Δx0,Δy0)

[0050] Correct the established coordinate system until the slope error is equal to the calibration value of the involute template 8 or within the permissible error range of the instrument. This indicates that the measurement coordinate system coincides with the workpiece coordinate system and meets the calibration standard. Repeat the above steps to complete the calibration of the large gear measuring instrument 9 and then perform involute tooth profile measurement.

[0051] The above description is merely the technical method and implementation method of the present invention. The protection scope of the present invention is not limited thereto. Any equivalent replacement or change made by any person based on the technical solution and inventive concept of the present invention is covered by the protection scope of the present invention.

Claims

1. A method for tracing the value of an involute with a large base circle radius, characterized by: The following steps are included Step 1: Determine the coordinate system and value transfer parameters for value traceability: Establish three coordinate systems: the gear workpiece coordinate system, the measurement coordinate system of the large gear measuring instrument (9), and the design coordinate system of the involute template (8); Determination of the parameters for value transfer: an involute tooth profile cylinder (1) capable of value transfer, and a reference surface for spatial positioning; Step 2: Adjust the posture of the involute template (8): Placing the involute template (8) together with the six-degree-of-freedom fine-tuning device (10) on the upper end surface of the gear (7) to be measured; Step 3: Adjust the position of the involute template (8): The probe of the large gear measuring instrument (9) is used to measure the spatial positioning reference surface of the involute template (8), and the design coordinate system of the involute template (8) is made to coincide with the measurement coordinate system by fine-tuning the six-degree-of-freedom fine-tuning device (10); Step 4: Involute parameter calibration: When the involute parameter is calibrated, the involute template (8) rotates with the workpiece coordinate system, and the gear tooth profile deviation measurement method is used to measure the tooth profile deviation curve of the involute template (8). If the calibration standard is met, the calibrated large gear measuring instrument (9) can be used to measure the involute tooth profile. If the calibration standard is not met, proceed to the next step; Step 5: Eliminate coordinate system establishment errors and calibrate measuring instruments: By analyzing the tooth profile deviation measurement results F α Identify the coordinate system establishment error (Δx0, Δy0): F α =f(Δx0,Δy0) The established coordinate system is corrected so that the measurement coordinate system coincides with the workpiece coordinate system. Then, the third and fourth steps are repeated. After the calibration standard is reached, the involute tooth profile is measured.

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