초록 ▼

In injection-molding a plastic workpiece about a prefabricated permanent insert, a first quantity of plastic material is injected into one or more first-shot cavities through which a portion of the insert extends, thereby forming a corresponding number of annular spacers around that portion. After t

In injection-molding a plastic workpiece about a prefabricated permanent insert, a first quantity of plastic material is injected into one or more first-shot cavities through which a portion of the insert extends, thereby forming a corresponding number of annular spacers around that portion. After the spacer or spacers have solidified, the spacer-carrying insert is transferred to a second-shot cavity in which each spacer holds the insert separated from the walls of adjoining cavity sections. A second quantity of plastic material is then injected into the second-shot cavity to complete the workpiece by forming a sheath around the insert incorporating the spacer or spacers which are steadying same against lateral movement due to the pressure of the injected second-shot plastic.

대표청구항 ▼

A method of injection-molding a workpiece of plastic material containing a prefabricated slender insert permanently embedded therein, comprising the steps of: (a) introducing at least part of the prefabricated insert into a first mold portion which defines a generally annular first-shot cavity encir

A method of injection-molding a workpiece of plastic material containing a prefabricated slender insert permanently embedded therein, comprising the steps of: (a) introducing at least part of the prefabricated insert into a first mold portion which defines a generally annular first-shot cavity encircling a portion of the insert so introduced, said cavity being such as to form a spacer with an axially throughgoing recess adjacent the spacer periphery; (b) injecting plastic material into said first-shot cavity to form a generally annular spacer with an axial recess therein; (c) upon hardening of said spacer and removal thereof together with said insert from said first mold portion, introducing said insert with said spacer into a second mold portion having a second-shot cavity, of greater length than said first-shot cavity, divided along a centerline thereof by said spacer into two sections within which said insert is held substantially centered by positive contact of said spacer on all sides with the peripheral walls of said second-shot cavity except adjacent said recess; (d) injecting plastic material into said sections to embed said insert in a plastic sheath on opposite sides of said spacer, said material flowing through said recess from one side of said spacer to the opposite side thereof; (e) allowing the plastic material last injected to harden around said insert into a finished workpiece incorporating said spacer; and (f) removing said workpiece from said second-shot cavity.