Heuristics for Batch Machining at Reconfigurable Rotary Transfer Machines

Abstract

A problem of design of reconfigurable rotary transfer machines is considered. Parts are divided into batches. Parts of a batch are located at the loading position of rotary table in a given sequence and they are processed simultaneously. Operations are partitioned into groups which are performed by spindle heads or by turrets. Constraints related to the design of spindle heads, turrets, and working positions, as well as precedence constraints related to operations, are given. The problem consists in minimizing the estimated cost of the transfer machine, while reaching a given output and satisfying all the constraints. The proposed methods to solve the problem are based on sequential assignment of operations to machining modules. Experimental results with different heuristics are reported.Keywords: Computer-aided design, machining, optimization, heuristics.  INTRODUCTIONIn large serial production machining systems composed of multi-purpose and multi-position equipment with sufficiently high concentration of manufacturing operations in working positions are used. These manufacturing systems provide high productivity and working accuracy resulting in increased manufacturing efficiency. Nevertheless, the trend in today's market place requires more flexible and adaptive manufacturing systems (Makssoud et al., 2014(Makssoud et al., , 2015. A possible solution is to employ reconfigurable manufacturing systems (RMS). RMS are able to manufacture different types of products by batches without losing all other advantages of large series production systems. This paper deals with a problem of the optimal design of a reconfigurable rotary transfer machine with turrets for parallel machining of multiple parts. Such a machine is multipositional, i.e. parts are sequentially machined on m 0 (1, 2, …, m 0 ) working positions. One position of the machine (zero) is exclusively used for loading new billets and unloading finished parts. At each working position, several machining modules (spindle heads) can be installed to process the operations assigned to this position. They are activated sequentially or simultaneously. Sequential activation is realized by the use of turrets. Simultaneous activation is possible if machining modules are related to the different sides of the part and work in parallel. Horizontal and vertical spindle heads and turrets can be used to access to different sides of parts on a working position.We consider the case where only one vertical turret can be mounted at the machine or one spindle head common for all working positions. Several horizontal spindle heads and turrets can be used. However, there is only one horizontal spindle head or turret per position. Different parts are loaded in a given sequence and they are processed simultaneously by corresponding machining modules. When machining at all working positions is finished, the rotary table turns and the machining modules of turrets are changed (if necessary) in accordance with the part to be machined on that position. Since different parts a...

Design and Optimization of a Pneumatic Clamping System for Direct-Driven Rotary Tables

“…Since RTMs are intended to achieve maximum production efficiency [8], the rotary table undergoes high values of angular acceleration used to rotate the table. These systems are of great interest in the modern industry due to their high flexibility and efficiency [9].…”