1. Field of the Invention
This invention relates to a mold for producing moldings from a plastic compound. More particularly, the invention relates to a mold of the kind commonly referred to as a stack, tandem, or two-level mold.
2. Prior Art
Molds of this kind, which are particularly suited for relatively thin moldings of large area, have mold cavities on opposite sides of an intermediate mold part and runner channels extending through the intermediate mold part to the mold cavities from a feed channel provided in one of a pair of outer mold parts which define the mold cavities jointly with the intermediate mold part.
An example of a known mold of this kind is described in Du Bois, J. H. and Pribble, W. I.: PLASTICS MOLD ENGINEERING HANDBOOK, 3rd Ed., New York, N.Y., 1978, pp. 384, 385. In known molds of the aforementioned kind it is often difficult to obtain a uniform quality of the moldings, because the plastic compound has a tendency to flow in an unbalanced manner to the two sides of the intermediate mold part during the charging of the mold. Thus, the mold cavity or group of mold cavities situated on the side of the intermediate mold part which is closest to the feed channel are not charged simultaneously with the mold cavity or group of mold cavities situated on the opposite side. Moreover, it is difficult to remove the scrap--the solidified plastic material which remains in the channel system of the mold after the charging has taken place and which is attached to the moldings in the mold cavities--from the mold upon opening thereof.
USPTO Backgrounds
USPTO Backgrounds