Developing a Piercing Technique for Ceramic and Glass Sheets by Utilizing a High Impulsive Pressure

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Recent, remarkable development of new materials, such as fine ceramics and high-performance glasses, presented a new manufacturing problem. They have hard and brittle quality, and are difficult to work. Though various working processes available for such materials have been developed,they have the common disadvantage of low productivity and high equipment cost, and thus limited applicability.The present research attempted to develop a new piercing technique with no such problem as aforementioned by utilizing a high pressure caused under the impulsive compression of a viscoplastic pressure medium. The method was referred to as VIP Process, and its applicability was examined theoretically and experimentally. Results obtained may be summarized as follows :(1) The original VIP was shown to be successful in piercing a circular hole through four kinds of brittle materials, i. e., two inorganic glasses, GC composite and alumina sheets.(2) A method for estimating the impulsive pressure was presented using a linear viscoelastic model, and its validity was confirmed.(3) The piercing mechanism was clarified by the FEM analysis.(4) An improvement in the probability of successful piercing was given to the original method. As a result, two new methods were proposed, and shown to be useful.(5) From the viewpoint of practical use, a low speed compression method using a hydraulic press machine, referred to as VM Process, was proposed, and its validity was confirmed.(6) The AFM Process was introduced, and shown to be effective for improving the accuracy of the formed holes.(7) Finally, the combined method (VM/AFM or VIP/AFM Process) was proposed, and various special applications were accomplished through inorganic glass sheets : one-shot piercing of plural holes and piercings of noncircular holes and circular fine holes.