Abstract

This thesis mainly focuses on the study and application of the integration of Computer numerical control (CNC) machining and on-machine cutting tool measurement. According to the industry survey, in current aerospace industry, the usage of off-line tool setters is one of the most prevailing ways for cutting tools measurement. The following up manual tool data input is required so that the CNC machine will know the tool dimension and finish the assigned machining tasks. Off-line tool setters are often of high accuracy and the measurement results are reliable. However, due to its off-line characteristic, after the tool is used, its current dimension status cannot be known or updated. Thus the quality of the upcoming machined parts cannot be guaranteed. Moreover, the involvement of operators’ manual data input in the traditional method inevitably introduces human error to machining from time to time.
To improve the process of part machining and eventually achieve produced parts that are within tolerance, a new approach is proposed in this thesis on the integration of machining and on-line tool measurement. The idea is to perform tool measurement without unloading the tool from the CNC machine, and update the tool dimension data in the machine control before the tool is used to machine the part. The key to this approach is the employment of a laser tool setter, an optoelectronic device that has the ability to communicate with the CNC control. Analysis on kinematics of this new type of device is conducted and its method of communication with CNC machine control is described.
Special software on CNC machine control level must be utilized to achieve the objective of on-machine measurement. Custom macros features of FANUC controls is used to suit the needs of parametric programming. The discussions on custom macros feature are carried out in this thesis. With the measurement method established, measurement uncertainty of the system will be discussed in depth. Considering the special attributes of the laser tool setter, the tool geometry and the machine control, an optimized measurement strategy is studied and proposed.
Finally, experiments are carried out to verify the accuracy and repeatability of the measurement system. Application on rejecting out-of-tolerance tool being used in machining is also discussed. The result of applications shows the measurement system is suitable for industry use.