The latest development of measuring technology for

2022-08-11
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The latest development of bevel gear measurement technology

1 overview

bevel gear transmission mechanism has been widely used in automobile, helicopter, machine tool and electric tool manufacturing industry. Different applications have different requirements for the performance and quality of bevel gears, which can be summarized as follows: ① there is a good contact area, which can reliably transmit power and torque; ② It has a well matched geometric shape and can transmit motion smoothly, so as to ensure uniform load, stable transmission, low vibration and low noise. Factories usually use double meshing instrument and rolling inspection instrument to detect contact spots to control the quality of bevel gears, but in fact, it is difficult to accurately determine the service performance of bevel gears

the accuracy measurement methods of bevel gears are similar to those of cylindrical gears, which can generally be divided into three kinds: ① coordinate geometric analysis measurement method. That is, taking the bevel gear as a geometric entity, the geometric elements of the bevel gear are measured for single geometric accuracy respectively; Gear measuring center is its main measuring instrument. ② Meshing comprehensive accuracy measurement method. That is, taking the bevel gear as a transmission element, the transmission accuracy, contact spots, vibration and noise are comprehensively measured. Its measuring instruments mainly include bevel gear single-sided meshing tester, bevel gear double-sided meshing tester and bevel gear rolling tester. ③ Measuring method of overall error of bevel gear. It takes the bevel gear as a geometric entity used to realize the transmission function, or uses the coordinate measurement method to measure the overall error of the bevel gear according to the single geometric accuracy measurement method, so as to realize the analysis and research of the internal relationship between the single geometric error of the bevel gear and the transmission accuracy and quality; Or according to the single-sided meshing measurement method and the meshing point scanning measurement method, the overall error of the bevel gear is measured, and the comprehensive motion accuracy, contact spot and individual geometric accuracy of the bevel gear are obtained. Therefore, the overall error measurement method of bevel gear is the integration and development of the first two measurement methods

with the development of coordinate measurement technology, computer control and measurement technology, the research on bevel gear overall error measurement technology has developed rapidly in recent years. Due to the improvement of the measurement performance and data processing ability of cylindrical multi-coordinate and multi-function measuring instruments such as gear measurement center, the coordinate geometric analysis measurement technology of bevel gear has developed from single geometric error measurement to overall error measurement of bevel gear, which improves the level of the whole bevel gear manufacturing technology, such as bevel gear design, processing, accuracy and quality detection and judgment, and performance prediction. The single-sided meshing point scanning measurement technology of bevel gears developed by our country and based on the "controllable point motion geometric measurement principle" and the bevel gear overall error measurement instrument developed based on this technology are also moving towards the front line of production, which further improves and develops the practical application of bevel gear measurement theory and measurement technology in our country

2 main measurement methods and instruments for bevel gear accuracy

2.1 coordinate geometric analysis measurement methods and instruments

Mechanical evolution coordinate straight bevel gear measuring instrument has been produced earlier, represented by Swiss MAG kp42, with high accuracy but complex structure. Since the CNC gear measurement center was introduced to the market around 1990, the coordinate spiral bevel gear geometry error measurement method has developed rapidly and been widely used. Nowadays, foreign gear measurement centers in the market, whether p63 from klinberg, Germany, gmx275 from Gleason/Mar and sigma 3 from M & M, have the function of measuring bevel gears. These instruments have reached level 1 specified by vdi/vde level, and the spatial measurement uncertainty is more than 2 microns; It can detect single geometric errors of bevel gears, such as pitch deviation (including single pitch deviation, cumulative pitch deviation, cumulative total pitch deviation), tooth profile deviation (including total profile deviation, profile shape deviation, and profile inclination deviation), tooth direction deviation (including total profile deviation, profile shape deviation, and profile inclination deviation), and can output three-dimensional tooth surface shape deviation topography, etc

2.2 comprehensive measurement method and instrument for single-sided meshing rolling inspection

the single-sided meshing rolling inspection method of bevel gears has been used in production for many years. Taking Gleason n0.513 rolling inspection machine as an example, under the condition of single-sided meshing of the tested bevel gear pair, simulate its working state, apply a certain speed and load, adjust v/h, and detect the colored contact area (spots) to determine the contact condition of the tested bevel gear pair; With the help of acceleration sensor and pickup, the vibration and noise are measured, and the tooth frequency harmonics are scanned and detected. This method belongs to the "quasi dynamic" measurement method, which is not complete and accurate enough for the accuracy detection of bevel gears. The bevel gear single-sided meshing tester, which uses the photoelectric encoder as the angle benchmark and is used to detect the tangential comprehensive accuracy of bevel gears, such as pske900 of klingeberg company in Germany, is particularly difficult to guide the adjustment of the parameters of the bevel gear processing machine tool according to the test results, so as to improve the processing quality of bevel gears. The cost performance is poor, so it is rarely used in production

in recent years, the Phoenix 500hct CNC bevel gear rolling inspection machine launched by Gleason company has the measurement functions of rolling inspection machine and single-sided meshing inspection instrument at the same time, which can not only measure the tangential comprehensive error of bevel gear, but also digitally measure the contact area of bevel gear, conduct three-dimensional structure noise analysis, etc. This model has advanced functions and represents the contemporary development level of this kind of products. Although it is expensive, it has been used by some users in China. Similarly, there are CNC bevel gear inspection machines such as klinberg gkc60 and Oricon T50

2.3 overall error measurement method and instrument

the overall error measurement of bevel gear is to integrate all the single geometric errors measured at each detection point on the working tooth surface of bevel gear into a bevel gear overall error diagram on the same rotation angle displacement coordinate according to the meshing sequence, and based on this, complete the analysis and measurement of the single geometric accuracy, comprehensive motion accuracy and contact state of bevel gear pair, Realize the evaluation and monitoring of the performance and quality of bevel gears. At present, the methods and instruments for measuring the overall error of bevel gears can be divided into two categories and three kinds. One is coordinate geometric analytic measurement method, which is divided into "point-to-point measurement method" and "point scanning measurement method". The instruments used in both methods are CNC gear measurement centers, but the measurement software packages used are different; The other is meshing kinematic geometry measurement method (i.e. meshing point scanning measurement method, which is the first method in China). The instrument used is bevel gear single-sided meshing tester, equipped with special measuring bevel gear and measuring software package

(1) coordinate point-to-point bevel gear overall error measurement

on the gear measurement center, use a three-dimensional probe along the tooth profile of the bevel gear as the one of the person in charge of the project and the two directions of the tooth direction, and according to the predetermined spacing, measure the geometric error of each detection point (usually 5 points on the tooth profile and 9 points on the tooth direction, a total of 45 points) on the tested tooth surface point by point. This method can avoid the friction between the three-dimensional probe and the measured tooth surface, which will affect the measurement results. The measurement method adopts the principle of "direct measurement". The specific steps are as follows: first, according to the adjustment parameters of the bevel gear processing machine tool and the geometric parameters of the cutter, the geometric parameters of the ideal machined tooth surface of the machined large and small bevel gears are calculated; Taking this tooth surface as the reference tooth surface, the geometric deviation between the actual tooth surface and the ideal tooth surface is measured by comparing it with the tooth surface of the actually machined (or heat-treated) large and small gears. With the help of the special match program, the machining parameters of the virtual machine tool corresponding to the measured actual tooth surface are determined; Then TCA analysis is carried out according to the meshing model, and the tangential comprehensive deviation and contact condition of the bevel gear pair are calculated to check whether they meet the requirements. If necessary, the corresponding software will recalculate and adjust the machining parameters of the machine tool according to the measurement results, so that the products with more satisfactory quality can be processed during the trial cutting again

(2) measurement of overall error of coordinate point scanning bevel gear

the method of point scanning measurement of bevel gear tooth surface with two-dimensional probe recently proposed by Osaka precision machine in Japan has obtained reliable and satisfactory measurement results. This method has the following characteristics: by controlling the rotation of the workpiece and the parallel displacement of the probe, the adverse effect of the friction between the probe and the tooth surface on the measurement is avoided; Due to the scanning measurement method, the measurement area can cover the whole tooth surface, including the tooth top and the area close to the large and small ends; There are a variety of measurement paths, usually the number of tooth profiles and tooth directions are 3 respectively, a total of 6; The number of samples on each scan line can reach 113 points. Due to the large sampling density, it can reflect the micro waviness on the tooth surface (this waviness is often the main source of unpleasant noise, which is difficult to measure with conventional point-to-point measurement methods). This method adopts the principle of "conjugate measurement", and its specific steps are as follows: first, the geometric parameters of the ideal machined tooth surface of the big gear are calculated according to the machine tool processing parameters and tool parameters, and the geometric parameters of the tooth surface of the virtual conjugate pinion conjugate with it and without transmission error are calculated; The actual machined gear tooth surface is compared with the ideal machined gear tooth surface, and the relative deviation of tooth profile and tooth direction is detected; The actual machined pinion tooth surface is compared with the calculated virtual conjugate pinion tooth surface, and the relative deviation of tooth profile and tooth direction is detected. According to the measured relative deviation, the three-dimensional tooth surface comprehensive deviation topography, tangential comprehensive deviation and contact shape (including contact path, contact area shape, size and position, etc.) of the bevel gear pair are calculated. Through physical measurement and comparison verification, the measurement and calculation results of point-to-point measurement method and point scanning measurement method are consistent

(3) measurement of the overall error of meshing point scanning bevel gear

the meshing point scanning measurement method of bevel gear proposed by Chengdu Institute of tools is the rolling measurement of single-sided meshing of bevel gear on the bevel gear single-sided meshing tester, which adopts special measuring bevel gear and the tested bevel gear according to the design installation position. Enterprises often lack the dynamic single-sided meshing of the instrument. The "basic" geometric parameters of the measured bevel gear pair are exactly the same as those of the measured bevel gear pair. During the measurement, the required tooth profile or tooth direction measuring prism is made on the gear teeth between the large and small measuring gears by using the corrosion method or paste method. The overall error measurement of the meshing point scanning of the bevel gear is completed by measuring the tooth profile or tooth direction measuring prism of the bevel gear and the mating tooth surface of the measured bevel gear. The number of measurement paths is related to the number of gear teeth. Generally, the origin of the 3+ curve shows a total of 6 local deviations of 3. The overall error measurement of bevel gear meshing point scanning adopts the principle of "local reference relative measurement". The specific measurement steps are as follows: according to the actual sports car/test run experiment (or experience) of the bevel gear pair, the manufacturer selects the bevel gear pair that can best meet the use requirements as the "reference" bevel gear pair (called the local reference), and its tangential comprehensive deviation, one tooth tangential comprehensive deviation and contact area shape are confirmed as the main reference indexes for evaluating the accuracy of this pair of bevel gear pairs. The measuring bevel gear is meshed with the local reference bevel gear, and the comprehensive tooth profile deviation local measurement (local reference bevel gear pair - measuring reference bevel gear pair, the same below) and comprehensive tooth direction are measured on the bevel gear single-sided meshing tester

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