The Study of Dynamic Balancing for High-Speed Presses

Abstract

The dynarnic problem of rnechanical presses is becoming a considerable issue while the press operating speed is increasing nowadays. For maintaining the reliable perferrnance and high productivity of high-speed press, the dynamic effects must be seriously coped with by an applicable dynamic balancing strategy, In this paper, a new dyriarnic balancing approach for high-speed presses is presented. Ihe approach is composed of an adjustable reeiprocating 1inkage balancer and proper counterweight disks disnibution, A notion of iterative procedure is adopted for obtaining the utmost superior balancing effect. The adaptive balancing within different operating speeds is taken into account, and the balancing performance is discussed, A practical clesign example en a drag-link press is presented for illustration. [[he conclusion showed that the shaking force/mement could be effbctively lessened by the proposed balancing method. design, A notion of iterative procedure, alternately adjusting the linkage balancer and modifying the counterweight distribution, is adopted for obtaining the utmost superioT balancing effect. Furtherrnore, to deal with consideral)le dyriamic forces of high-speed presses, adaptive balancing within different operating speeds is taken into account, and the balance perfbrrnance is discussed, A design example on Stephenson III six-bar mechanical press is preserited for illustration, BASIC ARRANGEMENT Fig, 1 shows a Stephenson III sjx-bar press mechanisrn (including links AB, BC, CD, CE and EF) and a linkage balancer (including links AB' and B'C'). The link r2 of the press mechanism and the link r2' of the balancer mechanism are both driven by an identical input with constant angu1ar velocity. Ihus, two reciprocating motions of the sliders would go in opposite directionssimultaneously. INTRODUCTION The pTess operating speed is increasing for providing more eencient production capability. At high operating speeds, ranged ever 500 2000 SPM (stroke per minutes), mechanical presses exhibit dynarnic effects which may induce vibration and noise. For rnaintaining the relial)le performance and high productivity of high-speed press, the dynamic effects must be seriously coped with, i.e., an app]icahle dynamic balancing strategy is necessary. flie unbalancing of press mechanisms is categorized in reciprocating-type unbalancing since the ram keeps periodically upward/downward motion. A conyentional strategy for press balancing is applying a linkage balancer mechanism, Such linkage balancer is often a four-bar slider driven by a crank or a rocker, The reciprocating motion of the linkage balancer simply provides shaking forces opposite to the dynarnic unbalance of the press rnechanism. Based on our previous study [1], a well-designed slider crank balancer could effectively lessen the eritical shaking forces down to 5%. On the other hand, Chiou [2] proposed an optimum balancing desigri of mechanical presses for precisien cutting by adding counterweight disks, and the result showed that the shaking moment coulcl be lessened to around 50% (compared with the dynamic behavior before balancing). Arakelian [3] pTesented a way for complete balancing of linkages, utilizing complicated gear-driven inenia counterweight. Yan [4] proposed a four-bar linkage balancing optimal design by varying input crank rotating speed. Briefly summarizing, utilizing the linkage balancer and adopting the counterweight disk method are apt at dealing with shaking force and shaking moment of mechanical presses respectively. Few papers discussed the balancing perfbrrnance with applying multiple rnethods at the sarne time. In this paper, we intend to present a new dyTiamic balancing approach for high-speed presses; this approach is cornposed of adjustable reciprocating balancer and the counterweight disks placement es x Fig. 1 PTess Mechanism and Linkage Balancer Copyrighr @ 200S by the Japan Society ofMechanical Engineers -1-