1. Field of the Invention
The present invention is directed to a plunger for use in forming parisons during the manufacture of glass containers with individual section (I.S.) machines.
2. Description of Related Art
A well-established process for manufacturing glass containers is known as the “blow-and-blow” process. In the “blow-and-blow” process, a gob of molten glass is introduced and partially shaped or molded into an object called a parison, which eventually will be formed into a glass container. The parison is formed by a blowing operation in a mold. The gob is introduced into the mold positioned over a plunger which acts to form the neck region of the parison. A vacuum is provided below the gob to urge the gob into the neck and around the plunger. The plunger is then withdrawn creating a space into which air is blown to expand the gob to the shape of the mold cavity. Thereafter, the shaped gob or parison is transferred to a finishing mold for a further blowing operation to form the parison into a container. Details of a suitable mechanism for plunger cycling are disclosed, for example, in U.S. Pat. No. 5,358,543 entitled “Air Tube Structure in a Glass Container Forming Machine”. The details of a suitable mechanism for connecting either a vacuum or blowing air to a piston for transfer through the plunger to the blank mold is described in U.S. Pat. No. 5,876,475 entitled “Glass Container Forming Process and Equipment”. Both of these patents are incorporated herein by reference.