Multi-cavity mold apparatus having independently controlled heated runners

• US 5,518,389 A
• Filed: 02/28/1995
• Issued: 05/21/1996
• Est. Priority Date: 10/16/1991
• Status: Expired due to Fees

• Current Assignee: KAO Corporation
• Original Assignee: KAO Corporation
• Inventors: Hata, Masaharu, Nonomura, Akira
• Primary Examiner(s): HEITBRINK, TIMOTHY W
• Application Number:
  US08/395,636
• Time in Patent Office: 448 Days
• Field of Search: 425/143, 425/144, 425/570, 425/572, 425/573, 264/40.6
• US Class Current: 425/144
• CPC Class Codes: B29C 2045/2687 controlling the filling thereof B29C2045/2691 takes precedence
• CPC Class Codes: B29C 45/27 Sprue channels ; Runner channels or runner nozzles
• CPC Class Codes: B29C 45/2737 Heating or cooling means therefor B29C45/7331 takes precedence
• CPC Class Codes: B29C 45/77 of velocity or pressure of moulding material
• CPC Class Codes: B29C 45/78 of temperature

Abstract

A multi-cavity mold has flow-distribution adjusting heaters provided for respective ones of main runners branching from a common channel so as to correspond to a plurality of cavities. The amount of resin charged into the cavities is made uniform from one cavity to the next by independently controlling the heaters. Sub-runners leading respective ones of the main runners are respectively provided with heaters for adjusting gate finish. The gate finish and moldability are improved by independently controlling these heaters. The main runners hold enough resin for at least one shot, and pressure loss in the sub-runners is made equal to or greater than pressure loss in the main runners.

Claims

1. A multi-cavity mold apparatus, comprising:

a plurality of sets of runners, each of said sets of runners comprising a first runner and a second runner;

said first runner of each of said sets of runners having a proximal end and a distal end, a proximal end of said first runner of each of said sets of runners being attached to a supply of molten resin, said first runner being capable of holding an amount of molten resin necessary for at least one molding operation;

said second runner of each of said sets of runners being attached on a first end of a corresponding said first runner at said distal end, a second end of said second runner serving as a gate facing a cavity;

each of said plurality of sets of runners further comprising (i) first independently controllable temperature regulating means for flow-distribution adjustment and (ii) second independently controllable temperature regulating means for gate finish adjustment, said first independently controllable temperature regulating means being provided on said first runner of each of said sets of runners for regulating the temperature of the molten resin necessary for at least one molding operation held therein, and said second independently controllable temperature regulating means being provided on said second runner of each of said sets of runners for regulating the temperature of the molten resin in the gate portion for gate finish adjustment;

wherein said first and second independently controllable temperature regulating means enable (i) a temperature of each of said plurality of sets of runners to be independently controlled and (ii) a temperature of each of said first and second runners of said plurality of sets to be independently controlled.

2. An apparatus according to claim 1, wherein a flow passage cross-sectional area of at least one of said second runners is less than a flow passage cross-sectional area of at least one of said first runners.

3. An apparatus according to claim 1, wherein said second independently controllable temperature regulating means is provided in respective ones of said second runners.