Research On Methodology Of Micro Diameter Tool Measurement Based On Tiny Aperture Imaging

The level of intelligent PCB numerical control drilling machine is one of themain benchmark of each equipment manufacturer. For the purpose of cost downand filling in technical gap in this field, it’s highly demanded that function ofautomatic tool diameter measurement to be developd by our own. Commonsolution in the industry is to use tiny aperature imaging and direct CCD imagingwith point light source as a sensor to measure tool diameter. Due to costlimitation, tiny aperature imaging is chosen in this paper.Firstly the method of calculating tool diameter by using tiny aperatureimaging is discussed in this paper, then a new method of design on using toolingdiameter detection sensor is proposed after discussion on a method used abroadand its defects. For tool diameter measurement control card, beause drilling toolhas scraps collecting slot, different positioning of tool will lead to differentmeasurement result, a simple method, by rotating tool, is used in this paper tomeasure tool diameter and measure control card will process the noised signalsoutput by detection sensor.Secondly an implementation of tool diameter measurement is introduced.For tool detection seneor, since high requirments for light emitting diode onpower distribution and degree of collimation, infrared emitting dioad is chosen toreplace conventional laser emitting diode, thus both save cost and simplifydesign. In debugging process, problems are well addressed on eliminating cirticalnoise, adjustment of window slide position and compensation of light brightnessin the implementation of tooling measurement circuit. In the meantime, solutionis dicussed regarding precision and high fault rate. For noised signals processingoutput by tool measurement control card, noise pattern was found during theimplementation and a simple solution was used to recover correct signals fromnoised signals.In the end tests were performed on tool measurement sensor and controlcard, the result showed that initial requirements were met and it also presentedthat the smaller tool diameter is, the higher failure rate. Furthermore, main sources which caused deviation of tooling detection and measurement areanalyzed, in addition, relative error caused by various factors is analyzed. Basedon the analysis, conclusion is drawed that main deviation comes from sensorlight streamer diameter.This paper provides a development method for similar tools and microdiameter detection and measurement.