| 摘要 |
<p>This invention relates to an improved valve pin for an injection molding system and a method of making the same. The elongated valve pin has a tip end portion which extends from a larger driven end portion into the flow of melt to the cavity. The elongated tip end portion is provided with a desired combination of strength and thermal conductivity by having a copper core inside a steel casing. The casing is made by brazing a tip end cap member to a hollow sleeve. A predetermined quantity of copper wire is then inserted into the casing and melted in a vacuum furnace to form an integral construction. The excess sleeve is then cut off and the end is brazed into a well in the driven end portion of the valve pin. The tip end cap member is then machined to provide a tip end of a desired shape. Filling the copper into the steel casing in a vacuum furnace bonds them together without any insulative spaces, thereby relatively inexpensively providing a valve pin structure which has the necessary structural strength to withstand repeated closing forces, while at the same time providing for the improved transfer of heat along the valve pin to the gate area.</p> |
