Abstract: The injection blow molding machine of this invention has a small indexing plate to which heads of different size can be connected. A small head can be used for long core rods when making parts of long length. Larger heads are connected to the indexing plate for accommodating more and shorter core rods. The same machine can, therefore, be used for making different parts of a variety not possible on standard injection blow molding machines. Special features of construction prevent the blowing air from exerting an upward pressure on the head that carries the core rods; and an improved cam mechanism operates air valves without exerting side thrust against the head. An indexing alarm prevents operation of the machine when not properly indexed at the operational stations.

Abstract: This method makes plastic book covers which have stiffer front and back panels and which have diminished plasticizer migration between the cover and any contacting cover or other adjacent surface. The covers are cross-linked to a limited extent to improve the elasticity of the hinge lines; and to a greater extent at the back and front cover areas to add stiffness to the plastic material. Laminated plastic covers are made with the different layers made of material that responds to cross-linking chemicals or radiation to different degrees, The covers can be made of expanded plastic and laminates.