Method of operating an injection molding machine with continuously operating plasticizing unit

• US 7,815,838 B2
• Filed: 09/29/2006
• Issued: 10/19/2010
• Est. Priority Date: 04/14/2000
• Status: Expired due to Fees

• Current Assignee: Kraussmaffei Technologies GmbH (KraussMaffei Group GmbH)
• Original Assignee: Kraussmaffei Technologies GmbH (KraussMaffei Group GmbH)
• Inventors: Zimmet, Rainer
• Primary Examiner(s): Hug; Eric
• Assistant Examiner(s): MINSKEY, JACOB T
• Application Number:
  US11/537,125
• Publication Number:
  US 20080079196A1
• Time in Patent Office: 1,481 Days
• Field of Search: 425557-561
• US Class Current: 264/328.1
• CPC Class Codes: B29C 2045/466 supplying the injection unit directly by a compounder
• CPC Class Codes: B29C 2045/533 using a continuously rotating plasticising screw
• CPC Class Codes: B29C 2045/547 continuously rotating plasticising screw cooperating with a single injection plunger B29C45/542 takes precedence
• CPC Class Codes: B29C 45/532 using a hollow injection ram co-operating with a coaxial screw
• CPC Class Codes: B29C 45/54 and plasticising screw B29C45/532 takes precedence

Abstract

In a method of operating an injection molding machine of a type having an injection plunger for pushing melt from an injection space anteriorly of an injection plunger into an injection mold, a plasticizing screw of an extruder is continuously operated to continuously feed melt through a melt channel into the injection space. A passage through the melt channel is closed to allow backup of melt backwards into the extruder, and the injection plunger is moved forward to inject a shot amount from the injection space into the injection mold.

Claims

1. A method of operating an injection molding machine of a type having an injection plunger for pushing melt from an injection space anteriorly of an injection plunger into an injection mold, said method comprising the steps of:

continuously operating a plasticizing screw of an extruder to continuously feed melt through a melt channel into the injection space, wherein the plasticizing screw defines an axis and is immobile in a direction of the axis;

closing a passage through the melt channel to allow backup of melt backwards into the extruder; and

moving the injection plunger forward to inject a shot amount from the injection space into the injection mold.

2. The method of claim 1, and further comprising the step of closing the melt channel during at least one of an injection phase and afterpressure phase.

3. The method of claim 1, and further comprising the step of operating a rotary drive to continuously operate the plasticizing screw at reduced speed during at least one of an injection phase and afterpressure phase.

4. The method of claim 1, wherein the extruder includes two of said plasticizing screw which rotate in a same direction.