Current situation and development of the hottest g

Current situation and development of gear measuring instrument

gear measuring instrument is a relatively rich concept. It includes not only instruments for detecting various gears, but also instruments for detecting worm gears, worms, gear cutters and transmission chains. There are many kinds of gears with complex geometric shapes, and many parameters characterize their errors. Therefore, there are many kinds of gear measuring instruments

the research on gear measurement technology and its instruments has a history of nearly 100 years. In this not short development process, there are six landmark events:

(1) in 1923, Zeiss company of Germany successfully developed an instrument called "tooth surface tester" for the first time in the world, which is actually a mechanical generative universal involute tester. On this basis, after improvement, Zeiss launched a practical instrument in 1925 and put it on the market. The length standard of the instrument adopts optical glass linear ruler, and its line distance is 1 micron. The appearance of this instrument marks the beginning of gear precision measurement. VG450, which is widely used in China, is an improved product of this instrument

(2) in the early 1950s, the emergence of mechanical generative universal helix standard instrument marked the realization of comprehensive control of gear quality

(3) in 1965, Dr. R. Munro of Britain developed a grating type single meshing instrument, marking the possibility of high-precision measurement of gear dynamic performance

(4) in 1970, the gear overall error measurement technology developed by Chinese engineers and technicians, mainly Huang tongnian, marked the beginning of gear measurement by kinematic geometry

(5) in 1970, the American fellow company exhibited microlog50 at the Chicago Expo, marking the beginning of the use of the CNC gear measurement center

(6) in the late 1980s, Osaka Seiji, Japan, launched a non-contact tooth surface analyzer ps-35 based on the principle of optical holography, marking the beginning of the non-contact measurement method of gears

the development of gear measurement technology in the past century is reviewed as a whole, which is mainly reflected in the following aspects:

(1) in terms of measurement principle, the development from "comparative measurement" to "meshing motion measurement" to "modeling measurement" is realized

(2) in terms of the technical means to realize the measurement principle, it has gone through the evolution from "focusing on machinery" to "electromechanical combination", until today's "optical mechanical electrical" and the comprehensive integration of information technology

(3) in terms of the expression and utilization of measurement results, it has experienced a leap from "indicator plus visual reading" to "recording instrument recording plus manual research and judgment" to "computer automatic analysis and feedback of measurement results to the manufacturing system". At the same time, the gear measuring instrument has experienced the evolution from a single variety and single parameter instrument (typical instrument has a single disc involute tester), a single variety and multi parameter instrument (typical instrument has a tooth profile and tooth direction tester) to a multi variety and multi parameter instrument (typical instrument has a gear measuring center)

In the past 50 years before the 1970s, the world has developed various types and specifications of mechanical generative instruments for measuring basic parameters such as tooth profile, helix, tooth pitch, etc. These instruments form the specified standard motion with the help of some precision mechanisms, and then compare with the measured ones to obtain the size of the measured error. Many kinds of mechanical involute generating mechanisms have been developed in the world, such as single disc, base circle lever type, relying on mode, etc. Among them, the disc lever type, which has become a new raw material for knitting socks, is the most widely used. Instruments belonging to this category include Zeiss VG450, Carl mahr 890 and 891s, Maag sp60 and HP100, Osaka precision machine gc-4h and gc-6h, and Harbin Measuring and cutting tools factory 3201, etc. For the measurement of tooth profile error, the mechanical generative measurement technology is limited to the measurement of involute tooth profile error. It is difficult to measure the tooth thickness of the end face of non involute gears by generating method, because the generating mechanism is too complex and lack of versatility. For the precise spiral generating mechanism, the principle of sine ruler is mainly used, but the ways of how to accurately convert the linear motion of sine ruler into the rotary motion of the measured workpiece are different. This mechanism is most typical in the measurement of hob helix, such as UWM rolling measuring instrument produced by German fette company, universal rolling measuring instrument produced by Zeiss factory, BH of the former Soviet Union ИИ Designed universal rolling measuring instrument, su-130 hob measuring instrument of samputensili factory in Italy, universal hob measuring instrument produced by Michigan company in the United States, pwf250/300 of klingelberg company, etc. Before the 1970s, the mechanical generative measurement technology had been developed and tested in production practice. Despite this, there are also some shortcomings: its measurement accuracy still depends on the accuracy of the generating mechanism, the mechanical structure is complex, the flexibility is poor, and measuring a gear requires multiple instruments. So far, the instruments based on these technologies are still the common means of testing gears in some factories in China

The year 1970 was the turning point of gear measurement technology. The appearance of gear integral error measurement technology and gear measuring machine (Center) solves a difficult problem in the field of gear measurement, that is, to quickly obtain all the error information of gears on one instrument. Although these two technologies are based on modern optical, mechanical, electrical, computer and other technologies, they have taken different technical routes. Gear overall error measurement technology is to extract single error and other useful information from comprehensive measurement. After 30 years of improvement and promotion, the measurement method of gear overall error has developed into the kinematic geometry measurement method of traditional components in China. Its basic idea is to take the measured object as a rigid functional component or transmission component to mesh with another standard component, and calculate the measured error by measuring the meshing motion error. The distinctive feature of kinematic geometry measurement method is that it vividly reflects the gear meshing transmission process and accurately reveals the variation law of gear single error and the relationship between errors, which is especially suitable for gear process error analysis and dynamic performance prediction. The instrument using this method has the advantage of high measurement efficiency and is suitable for parts detection in mass production. Typical instruments are CZ450 gear overall error measuring instrument, csz500 bevel gear measuring machine and cqb700 cycloid gear measuring instrument produced by Chengdu Tool Research Institute. The gear measuring center adopts the principle of coordinate measurement, which is actually a cylindrical (polar) coordinate measuring machine. The essence of "coordinate measurement" is "modeling measurement". For gears, the principle of modeling coordinate measurement is to take the measured part as a pure geometry (relative to the "kinematic geometry method"), measure the coordinate values of the actual parts (rectangular coordinates, cylindrical coordinates, polar coordinates, etc.) and compare them with the mathematical model of the ideal shape, so as to determine the measured error. The coordinate measurement method is characterized by strong versatility, simple host structure and high measurement accuracy. The idea of measuring gears by coordinate method has long existed. For example, the combination of universal tool microscope and dividing head can also be used to measure gears. However, this static measurement method is not only inefficient, but also the measurement accuracy can not be guaranteed. The development of modern optoelectronic technology, microelectronics technology, computer technology, software engineering, precision machinery and other technologies has really provided a solid technical foundation for coordinate measurement to show its advantages. So far, CNC gear measurement centers have been produced in the United States, Germany, Japan, Switzerland, China, Italy and other countries. The typical products abroad are M & M's 3000 series and klingelberg's P series; The typical domestic products with the advantages of high efficiency, energy saving and high cost performance are cgw300 horizontal measurement center of Chengdu Tool Research Institute and 3903 gear measurement center of Harbin Measuring and cutting tools factory. Although the gear measurement centers in various countries are similar in principle, there is a certain gap in the implementation method. It is mainly manifested in:

(1) in terms of measuring sensors, although high-precision circular gratings are generally used for angle measurement, the measurement length varies due to different measured objects. For gears with high accuracy requirements or workpieces with long axial dimensions, dual frequency (or single frequency) laser interferometers are generally used as length Benchmarks (such as measuring involute or helix templates); In other cases, high-precision long gratings are used

(2) in terms of the accuracy of mechanical systems, high-precision bearings are necessary; The accuracy of linear guide rail is guaranteed by mechanical accuracy, and it is also achieved by error correction technology

(3) in terms of numerical control system, NC open-loop control was often used in the 1970s; After the 1980s, it was all controlled by CNC, most of which used DC servo motor or stepping motor. At present, AC servo system or linear motor has been used

(4) in terms of probe, there are inductance type and grating type; There are one-dimensional, three-dimensional, and even rigid. Rigid probe is without micrometer sensor. If a rigid probe is used, the instrument is usually dedicated

gear measuring center is generally composed of host machine, CNC numerical control unit, data acquisition unit, inter machine communication interface, computer and peripherals, measurement software and data processing software. The main features of the latest CNC gear measuring center today are: ① high efficiency, high precision and easy operation in performance. The measures taken include the optimal design of precision machinery, 32-bit CNC axis numerical control system, linear motor, three-dimensional probe and error correction technology. ② In terms of function, it includes the measurement of main error items of rotating parts such as gears (internal and external), gear cutters (hobs, gear shapers, shaving cutters), bevel gears, worm gears, worms, screws, convex gears, broaches, etc; Geometric tolerance measurement of shaft parts; Powerful analysis functions, such as contact analysis, process error analysis, tooth root shape analysis, parameter reverse calculation, etc; It can be coupled to the processing system for real-time data communication. ③ In terms of maintainability, it has the ability of fault self diagnosis and remote fault diagnosis. ④ Upgradeability. Including software upgradeability and hardware upgradeability

compared with mechanical generative measuring instruments, the advantages of CNC gear measuring center are self-evident. Its qualitative leap is to provide the possibility for the measurement of tooth profile of any shape, not limited to involute or linear tooth profile. The measurement of bevel gear, K worm (HOB) and C worm (HOB) is proof. CNC gear measuring center provides a tool for measuring and controlling nonlinear helical surfaces

since 1990, there have been several noticeable phenomena in the field of gear measurement technology around the use of graphene in digital economy related fields such as sensors and touch screens: ① the integration of gear overall error measurement technology and gear coordinate measurement technology. Chengdu Tool Research Institute has launched a gear measuring machine CZN450 with both standard (2) unstable installation foundation or loose anchor screws, quasi worm and probe, and foreign CNC gear measuring centers can also give "virtual overall error". ② Gear measuring center and CMM are integrated, such as rdaiance of TSK company and nd430 of process equipment company. ③ The combination of functional test and sub test. Simplified measurement is one of the development trends of gear measuring instrument. Gear overall error measuring instrument is accepted by gear manufacturing industry because it can give full information of gear efficiently

looking forward to the future, the relevant research and development priorities of gear measuring instruments are: gear Networking Measurement Technology; Virtual analysis technology of gear performance based on measured results (intelligent matching, dynamic performance prediction, etc.); Gear overall error measurement technology (index quantification, performance optimization, etc.); Intelligent analysis technology of gear error; The establishment of the concept system of gear statistical error and its corresponding measurement technology; Rapid measurement and analysis technology of gears in production site