Integrated Measurement Technology Of Large Deep-Diameter Ratio Holes And Multiple Geometric Quantities

Hole parts with large depth-diameter ratio refer to parts with hole depth and inner diameter ratio more than ten times.In the process of production,holes with large depth-diameter ratio have to go through two processes of rough boring and fine boring successively.Guarantee of geometric dimension after rough boring is an important factor to improve the processing efficiency of holes with large depth-diameter ratio,and measurement of geometric dimension after fine boring is also a necessary condition to ensure accuracy.The geometric dimensions of large depth-to-diameter ratio holes include straightness,roundness,aperture and wall thickness.At present,the commonly used measuring method is manual measurement of the above geometric dimensions one by one,with low automation,low accuracy and high requirement for workers' operation proficiency.The main research content of this paper is to develop an integrated high-precision measuring device,which can simultaneously measure the straightness,roundness,aperture and wall thickness of large-diameter ratio holes,and solve the problems existing in the current measurement.In order to measure the straightness of large deep-diameter ratio holes,the traditional measurement method uses push rod to drive the mirror to move in the holes,which is time-consuming and laborious to operate by photoelectric autocollimator.In order to measure the roundness and aperture of large deep-diameter ratio holes,the traditional measurement method uses self-made measuring instrument to measure four points of the same cross-section,and then fits the roundness and aperture.In order to measure the wall thickness of holes with large depth-diameter ratio,the traditional method uses ultrasonic thickness gauge to measure points on the circumference of the same cross-section of the outer wall of the tube,which can not correspond the angle information and data of the circumference,but can only measure the roughness information of the wall thickness;each of the above-mentioned measurement needs a long time and measurement accuracy.It's not very high.It seriously reduces production efficiency and productivity.From the above problems,it can be seen that there is an urgent need for a device which can simultaneously measure the linearity,roundness,aperture and wall thickness of large aspect ratio holes.Based on the above requirements,this paper studies the multi-geometry integrated measurement technology for large depth-diameter ratio holes.The research includes the following contents altogether.(1)This paper analyses the current measurement methods of straightness,roundness,aperture and wall thickness of large-depth-to-diameter ratio porous parts,analyses the current measurement requirements and puts forward a general scheme of integrated measurement of large-depth-to-aperture and multi-geometry.The straightness is measured by optical axis method,the roundness and aperture are measured by rotating a circle of contact displacement sensor,and the wall thickness is measured by non-contact ultrasonic method.Wave Thickness Meter Rotates for a Cycle to Measure.(2)According to the requirement of measurement accuracy,the error analysis of straightness measurement scheme is carried out,and a mirror swing measurement scheme is proposed to reduce the measurement error.The error analysis of roundness,aperture and wall thickness measurement scheme is carried out,and the basis of structure design and sensor selection is obtained.The evaluation methods of straightness,roundness,aperture and wall thickness are analyzed and optimized.(3)The specific structure of straightness measurement module is designed;the roundness and aperture variable measurement module is proposed and designed;the solution of the friction force of ultrasonic thickness measurement greater than the torsion of rotating disc is given and the structure design of the wall thickness measurement module is carried out,and a set of measuring prototype is built.The prototype can realize the measurement of the straightness,roundness,aperture and wall thickness of the parts with large aspect ratio.(4)The sensor used in the prototype is calibrated for its accuracy,and the experiment of measuring the linearity,roundness,aperture and wall thickness of the hole parts with large depth-to-diameter ratio is carried out.By comparing with the data measured by the coordinate machine,the accuracy of straightness measurement is 6 microns,the accuracy of roundness measurement is 3.4 microns,the accuracy of aperture measurement is 2.8 microns,and the accuracy of wall thickness measurement is 80 microns.All meet the requirements.