Research On Concentricity Measurement Method For Small Blind Hole

Concentricity is one of the geometric tolerances that must be marked foralmost all important shaft parts. The rational design and manufacture of it has agreat impact on rotary precision and fitting accuracy. Large concentricity error maycause the shock of shaft system and the whole device, leading to lubrication failure,bearing wear and other adverse consequences.There are many ways to measure concentricity error for parts in general size,such as the use of concentricity tester, CMM and roundness measuring instrument.Generally both the last two devices mentioned can get a high accuracy which canmeet the measurement requirements for most of high-precision parts, but the errorwill be great when the holes measured are small in size or have a large hole spacing.The holes we measured are both small in size and have a large hole spacing,and have no way to measure before us. In order to solve this problem we carried outa study of relevant research and proposed a new method of measurement.First, a contact measurement solution is presented after the study of the processof the characteristics of the parts under test.Then, developed a set of coaxial detection equipment, including mechanicalstructural parts, instrument box and software components. The mechanical structureincludes: fixture, platform body, vertical guide plate and the probe. Attention isfocused on how to use the theoretical derivation method, ANSYS finite elementsimulation and Matlab toolbox for probe assembly analysis; instrument box includes:secondary instrument circuit, A/D converter circuit and LED display; softwarecomponents includes: data collection, display and storing section, historical dataview section, statistics and report generation section.Finally, based on the equipment we designed, a lot of experiments had carriedout such as the calibration and measurement error analysis of the probe assemblyand so on. The experiments above verifies the accuracy and reliability of themeasuring device, and the device is proved to meet the accuracy requirements.