ENGINEERING SUPPORT PROBLEM FOR THE STABILITY ASSUARANCE IN DEEP DRILLING OPERATIONS FOR LARGE-SIZED FORGING AND PRESSING BLANKS WORK ON MULTI-PURPOSE CNC MACHINES

the article discusses the problem of technological stability assurance of deep drilling operations performed on automated equipment – multipurpose CNC machines. A group of large-sized forging parts and pressing blanks is viewed. It is shown that using a set of special drills and counterboring tools instead of universal horizontal milling machine makes it possible to avoid making special tools and contributes to the improvement of cutting modes, but the problem of stability assurance re-mains. A study of the hardness of such forgings revealed the unevenness of this characteristic in various parts of the work-piece. Despite the fact that, from the point of view of statistics, the totality of experimental data is homogeneous and the flow process of metallurgical forging production is stable, the revealed hardness variability turns out to be very sensitive for the subsequent stage of machining, namely for its special type like deep drilling. Experimental studies of chip formation in hole-making operations have proved that. It is noted that the task of managing the operability of tools and the quality of the re-sulting surfaces should be solved both at the stage of process design and just within operations. The latter can be solved through adaptive control, which is implemented on modern mass-produced multipurpose CNC machines in terms of the op-erating cutting power, which does not require retrofitting an automated machine-tool fleet for machining sites. The ra-tionale for the selection of factors and their variation levels in the construction of regression models used for design process and adaptive control of deep drilling operations on multipurpose CNC machines is given.

deep drilling, hardness, tool operability, roughness, adaptive control, cutting modes