Research Of Measurement Theory And Application Technique For Freeform Surface Based On Annular Roller Probe

Freeform surface are more and more widely applied in space flight, aviation, automobile, machines, mould industries and even costume manufacturing. The measurement for freeform surface is always the key step to actualise the detail design, manufacture and shape detection of parts. At present, the main measuring methods used for freeform surface are generally divided into two kinds: contact measurement and non-contact measurement, in which advantages and disadvantages exist. Usually a sphere probe is applied for contact measurement, and the efficiency is low and not suitable for on-line and on-machine measurement. A laser probe is often adopted in non-contact measurement, and the measuring speed is higher and the surface cannot be scratched. However, some superficial reflection or entire black surfaces are not suitable with this method because of the requirement of optical principle. In addition, the cost of equipment for non-contact measurement is much higher, and the reliability and stability are affected by sputtering chips and cooling liquid. To solve these problems, a new contact measurement technique is presented in which an annular roller probe is applied to measure the freeform surface. As such, some insufficiencies of traditional measuring techniques can be constrained to certain extent.When using an annular roller wheel probe to measure, the problems that the speed is low in contact measurement and the precision is susceptible in non-contact measurement can be voided. Here, the measurement theory for freeform surface based on annular roller probe is presented. By differential thought the measuring problem of two curved faces is converted into the measurement between a curved face and a plane. Base on this mapping principle, a mathematical model is set up to reverse the profile data of curved face and a reverse engineering algorithm is presented for complex surface measurement based on an annular roller probe. According to the mathematical model and algorithm proposed above, the accuracy and feasibility are proved for the measurement theory. For this method, the measurement for curved surface is transformed into curve lines, so the efficiency is greatly enhanced, and the data processing is simplified. In addition, the measurement system and equipment are designed and the hardware platform of measurement system is selected. Through measuring experiment, the measuring method is verified and analyzed. This measurement technique is the supplement of existing measuring methods and some parts with surfaces of revolution, which are difficult to implement on-line, on-tool and machining spot rapid survey, can actualize easily. It will have a positive promoting action on the development of complex surface manufacture technology.