Cutter dynamic reliability and failure rate method based on random process

Abstract

The present invention discloses a cutter dynamic reliability and failure rate method based on a random process. A failure criterion of a cutter is first defined, and a reliability mathematical model of the cutter is established based on the criterion. Based on a stress-intensity interference model, a cutter dynamic reliability mathematical model and a cutter failure rate mathematical model that take the number of times of impact loading and a machining time into consideration are established. The method of the present invention directly reflects a relationship between reliability and a failure rate and the number of times of impact loading and a machining time, and reliability and a failure rate of a cutter with any number of times of impact loading at any time may be calculated. When an allowable failure rate of a cutter is given, an early failure period and a random failure period of the cutter can be accurately determined, so as to guide a reliability test of the cutter and determine an index such as a reliable life.

Description

technical field [0001] The invention belongs to the technical field of mechanical processing, and relates to a method for determining the dynamic reliability and failure rate of a tool, in particular to a method for determining the dynamic reliability and failure rate of a tool based on a random process. Background technique [0002] my country's high-end CNC machine tools are in a disadvantaged position in the world, the main reason is the low reliability of machine tools. There are many factors that affect the reliability of machine tools, such as tool holder system failures, cutter head failures, electrical and hydraulic failures, etc., especially the failure of cutting tools accounts for 30% of the total failure probability of machine tools. In order to improve the life of the cutting tool and the reliability of the tool system, scholars at home and abroad have carried out some research. American scholars Mazzuchi and Soyer established a CNC machine tool tool reliabilit...

AI Technical Summary

Problems solved by technology

[0004] The above-mentioned domestic and foreign research on the reliability of cutting tool systems, from the experimental point of view, the research methods need to consume a lot of time and financial and material resources, and when conducting tool tests, the selection of geometry, physics and cutting parameters of the same batch of test tools They all have a certain degree of randomness. If they are processed according to a certain value, it will inevitably cause certain errors in the experimental results, and even give wrong conclusions.

From the perspective of the theoretical model, the above tool reliability models are all based on the static reliability model, and the calculated reliability is actually the reliability when the random load acts once or for a specific number of times, and it cannot reflect that the tool reliability varies with the The changing law of impact load times and cutting time

However, the tool is always in a dynamic cutting process during the machining process, and its accuracy and precision are far from enough to analyze with a static model.

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