Method and apparatus for parallel alignment of opposing mold surfaces by

Abstract

In a mold apparatus, the receiving molding surface and the opposing molding surface are each mounted coaxially and in sliding fashion within an alignment means. Both of these alignment means have an equal number of spaced apart alignment pads which are positioned such that opposing pads will be in cooperable engagement with each other during pressing. Utilizing the disclosed apparatus, a method for molding precisely shaped articles, such as magnetic memory disc substrates which require precisely parallel, opposite molded surfaces, is described. Simply stated, the method utilizes the alignment pads' thermal expansion characteristics to induce a controlled level of thermal distortion to obtain pad lengths which result in parallel opposing molding surfaces. There are two methods for accomplishing this pad length required for parallel molding surfaces: the first method, controlled heating, consists of introducing heat to a pad to cause it to expand, thereby extending the length thereof; the second method, controlled cooling, consists of introducing cooling to a pad to cause it to contract, thereby shortening the length thereof. Once pad lengths are adjusted and thus the molding surfaces are parallel, the glass article may be pressed. This method is suitable for press molding any glass article which requires parallel opposing surfaces, regardless of the article's thickness.