Profiled Piston Pin Hole Contour Measuring Instrument Developed

Piston is the critical part of an engine. All the power of an engine needs to be transmitted by the assembly of the pin bore and the piston pin. With the increase of the power of an engine, the load-bearing of the pin bore and piston pin is becoming larger and larger accordingly. Non-cylindrical pin bore designed as elliptic or taper pin bore instead of cylindrical pin bore can effectively reduce its stress convergence and increase its service life. The machining of non-cylindrical pin bores has been gradually becoming a trend. However special instruments designed for the measure of the profile of non-cylindrical pin bores are few in our country.This paper develops the research of the measure instrument of non-cylindrical pin bore which can meet the users' requirements at the aspects of its precision, efficiency, and economy. Based on the analysis of the present measure means of pin bores, this paper put forward a new measure means—the contact measure method with a single probe, that is, a probe with high-accuracy moves along the generatrix of a pin bore, and then the radial variety of the profile is measured. After the A/D transformation, filtering and fitting of the radial variety , the parameters of the profile then can be calculated. The validation of this method had been proved by many practical testing experiments.Firstly, the paper introduces the source of this project, the state-of-the-art in this field and the author's main work. And it also introduces the selection of the whole scheme and the design of the measuring software in detail. Secondly, it discusses the design of the hardware of the measure instrument and designs the hanging-pole support. The multi-thread techniques and the interrupt techniques used in the software are introduced too. And also, the ascertain of the dividing points in the course of the data-fit and the evaluation of the measure results are particularly analyzed. Lastly, the feasibility of the method is validated by testing experiments and the analysis of the data.