Patent Application
20080095876
A better understanding of the exemplary embodiments of the present invention (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the exemplary embodiments along with the following drawings, in which:
The drawings are not necessarily to scale and are may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the exemplary embodiments or that render other details difficult to perceive may have been omitted.
With reference to
The exemplary embodiment of the barrel assembly 138 includes a melt passageway 148 that extends through the components of the barrel assembly 148. The melt passageway 148 of the first and second barrel portions 140, 143 is disposed along a liner 146, 146′ made from a corrosion resistant material, such as STELLITE to protect the barrel substrate material, commonly made from a nickel-based alloy such as INCONEL, from the corrosive properties of the molding material. The components of the barrel assembly 138 are shown to be held together, at least in part, through the use of fasteners 51. The first and second barrel portions 140, 143, the barrel head 142, and the machine nozzle 144 may include a heating structure 50 for controlling the temperature of the molding material in the melt passageway 148.
The exemplary barrel assembly 138 further includes a cooling structure 180 that is arranged to overlap flange portions at the interface 164 of the barrel head 142 and barrel liner 146 to provide alignment therebetween and to cool an interface 164 defined between adjacent annular faces 173, 173′ of the barrel head 142 and the barrel liner 146. The cooling structure 180 is preferably an annular body with a coolant channel 182 defined therein. The cooling structure 180 preferably includes a temperature monitoring structure (not shown), such as a thermocouple, to provide temperature feedback to a controller (not shown) in order that a flow and temperature of the coolant to the channel 182 may be controlled to effect a temperature control of the interface 164. The exemplary barrel assembly 138 further includes an auxiliary member 141 that surrounds the cooling structure 180 as a structural spacer. Preferably, the interface 164 includes a small gap between the annular faces 173, 173′ when the barrel head 142 and first barrel portion 140 have been controllably heated to a processing temperature.
Alternatively, the interface 164 is configured (not shown) such that there is no gap between the annular faces 173, 173′ when the barrel head 142 and first barrel portion 140 have been controllably heated to the processing temperature. The interface 164 may be further configured such that there is a face seal between the annular faces 173, 173′, with a sealing force acting therebetween, when the barrel head 142 and first barrel portion 140 have been controllably heated to the processing temperature.
Likewise, a cooling structure 180′ may also be arranged to overlap flange portions of the barrel liner 146, 146′ projecting from the mating ends the first and the second barrel portion 140, 143. The cooling structure 180′ preferably aligns the first and second barrel portions 140, 143, and also cools an interface 164′ defined between adjacent annular faces of the barrel liners 146, 146′. An auxiliary member 141′ surrounds the cooling structure 180′ as a structural spacer. Alternatively, other means, such as dowels, may be provided to align the first and second barrel portions 140, 143.
Likewise, a cooling structure 180″ may be arranged to overlap flange portions at the interface of the barrel head 142 and machine nozzle 144 to provide alignment therebetween and to cool an interface 164″ defined between adjacent annular faces of the barrel head 142 and the machine nozzle 144. An auxiliary member 141″ surrounds the cooling structure 180″ as a structural spacer.
A technical effect of a controlled cooling of the interface 164, 164′, 164″ is a corresponding control of the viscosity of the molding material in the vicinity of the interface 164, 164′, 164″ for controlling the leakage of molding material therethrough. Preferably, the cooling structure 180 controllably cools the interface 164 sufficiently to form a seal 160, 160′, 160″ of at least partially solidified molding material in the vicinity of the interfaces 164, 164′, 164″.
In accordance with an exemplary alternative embodiment the barrel assembly (not shown) in a two-stage injection unit (not shown), the seal 160, and variants thereto, may also be used at an interface between the barrel assembly and a shooting pot (not shown).
In accordance with another exemplary alternative embodiment the barrel assembly (not shown) the cooling structure is integrally formed with one, or both, of the barrel components to be sealed.
In accordance with yet another exemplary alternative embodiment the barrel assembly (not shown) the cooling structure recessed into one, or both, of the barrel components to be sealed and in so doing the auxiliary member is no longer required.
The description of the exemplary embodiments provides examples of the present invention, and these examples do not limit the scope of the present invention. It is understood that the scope of the present invention is limited by the claims. The concepts described above may be adapted for specific conditions and/or functions, and may be further extended to a variety of other applications that are within the scope of the present invention. Having thus described the exemplary embodiments, it will be apparent that modifications and enhancements are possible without departing from the concepts as described. Therefore, what is to be protected by way of letters patent are limited only by the scope of the following claims:
