Optimization of Machining Modes for Multi-head Machines under Group Replacement of Tools

Abstract

A problem of defining of machining modes for paced multi-station transfer lines composed of workstations with multi-spindle heads is considered. Each spindle head performs some block of operations with its tools. Each tool of a spindle head has its own spindle speed. All tools of a spindle head have the same feed per minute. All spindle heads of all workstations are activated simultaneously. Constraints on ranges of cutting parameters, cutting process characteristics, required productivity, as well as dependences of tools life time on the cutting parameters are given. To decrease the idle time of the equipment the tools are grouped to implement their replacement simultaneously. All tools of each group are replaced after processing the same number of parts, where the number is taken from the given set. The problem consists in finding the cutting parameters and the tools grouping to minimize the unit production cost under the above constraints. The proposed method is based on the combination of fragmentary parameterization concept and the coordinate-wise descent over groups of variables of the parameterized problem. A numerical example is presented.