Patent Application
20070252312
1. Field of the Invention
The present invention relates generally to controlling extrusion of a parison on a free-hanging parison blow molder.
2. Related Art
In some blow-molding devices, a parison is extruded downward from a die-head so that the parison is free-hanging. A mold is moved into position to close around the free-hanging parison, and the container is blow-molded.
For larger containers, however, the portion of the parison extruded must be longer than for smaller containers, especially for tandem container, where the containers are blown in pairs, neck-to-neck or base-to-base, and for handle-ware packages. Longer parisons have a tendency to curl. When the mold closes around a curled parison, the resulting container is likely to be misshapen.
What is needed is a way to extrude longer parisons that overcomes shortcomings of conventional solutions.
In summary, the present invention, in an exemplary embodiment, provides an apparatus, comprising: a gripper, adapted to grasp and release an end of an extruded parison while the parison is being extruded; and an extendable support, coupled to the gripper, adapted to raise the gripper to grasp the parison and to lower the gripper, whereby the parison is pulled downward and kept substantially straight.
In another exemplary embodiment, the present invention provides a method comprising: extending an extendable support; grasping a parison with a gripper coupled to the extendable support, while the parison is being extruded, and release an end of an extruded parison; and lowering the extendable support, whereby the parison is pulled downward and kept substantially straight by the gripper.
Further objectives and advantages, as well as the structure and function of preferred embodiments will become apparent from a consideration of the description, drawings, and examples.
The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.
Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without parting from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.
In an exemplary embodiment, an apparatus according to the present invention includes a parison gripper that extends to grip the bottom of an extruding parison and pulls the parison gently downward until the mold closes over the parison. The parison gripper may become the base of the mold, or may remain separate from the mold.
Many configurations for gripper 106 are possible. Functionally, gripper 106 may grasp and release a parison, and may be coupled to the extendible support 108.
In one exemplary embodiment (not shown), gripper 106 may be separate and independent of the molds used. In such an embodiment, gripper 106 may effectively pull parison 102 downward for a period of time before a mold is moved into position around the parison. In the embodiment shown in
Gripper 106 may alternatively not form a part of the mold 110. In this embodiment, once the mold closes around a parison 102, the mold 110 and parison 102 may be removed to another area in the manufacturing process while a new parison is stretched by the gripper
The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.
