Injection mold having a wear resistant portion and a high heat transfer portion

Abstract

Disclosed is a preferred mold design for producing plastic, injection molded preforms, which may be blow-molded into a container of a final, desired shape. A preferred mold includes a combination of hardened material components and high heat transfer material components to provide a mold having good wear characteristics, for a sufficiently long useful life, and to enable rapid cooling of the injected preform, in order to reduce the cycle time of an injection and cooling cycle. In some arrangements, the hardened materials may form a portion of the preform cavity thereby slowing the rate of cooling in those areas and inducing a semi-crystalline or crystalline structure in the cooled preform.

1 . A mold assembly comprising:
 a core section having a core member comprising a core contact surface;   a cavity section having a cavity contact surface, the cavity contact surface comprising a hardened material, the cavity section comprising a high heat transfer material; and   a mold cavity generally defined between the core section and the cavity section when the core contact surface contacts the cavity contact surface.   
   
   
       2 . The mold assembly of  claim 1 , wherein a significant portion of the cavity section comprises a high heat transfer material. 
   
   
       3 . The mold assembly of  claim 1 , wherein the cavity section comprises a threaded finish portion. 
   
   
       4 . The mold assembly of  claim 3 , wherein the threaded finish portion comprises a lower rate of heat transfer than the high heat transfer material. 
   
   
       5 . The mold assembly of  claim 1 , wherein the core contact surface comprises a hardened material. 
   
   
       6 . The mold assembly of  claim 1 , wherein the hardened material comprises steel. 
   
   
       7 . A mold apparatus for producing a plurality of multi-layer preforms, comprising:
 a core section comprising a plurality of core members, each core member having a core contact surface;   a first set of mold cavities configured to mate with at least some of the core members to produce a first injection layer therebetween;   a second set of mold cavities configured to mate with at least some of the core members to produce an over injection layer over the first injection layer;   wherein each mold cavity comprises a cavity contact surface and a main mold portion, the main mold portion comprising a high heat transfer material;   wherein the core contact surfaces and the cavity contact surfaces comprise a hardened material;   wherein the core contact surfaces are configured to contact the cavity contact surfaces of the first set of mold cavities when a first injection layer is being produced; and   wherein the core contact surfaces are configured to contact the cavity contact surfaces of the second set of mold cavities when the core section is indexed toward the second set of mold cavities.   
   
   
       8 . The mold apparatus of  claim 7 , wherein the core section is rotated relative to the first and second sets of mold cavities. 
   
   
       9 . The mold apparatus of  claim 7 , wherein the first and second sets of mold cavities are located on a single cavity section. 
   
   
       10 . The mold apparatus of  claim 7 , wherein the first and second sets of mold cavities are located on a separate cavity sections. 
   
   
       11 . The mold apparatus of  claim 7 , wherein the core members comprise a high heat transfer material. 
   
   
       12 . An injection mold assembly comprising:
 a cavity section having a first portion, a gate portion and a second portion positioned between the first portion and the gate portion, the first portion comprising a hardened material that defines a cavity contact surface, the second portion comprising a high heat transfer material and at least partially defining a cavity mold surface, the hardened material being more resistant to wear and having lower heat transfer properties than the high heat transfer material;   a core section having at least a core contact surface and a core mold surface, a portion of the core section forming the core contact surface comprising a hardened material, wherein the cavity contact surface and the core contact surface include tapered mating surfaces; and   a mold cavity formed by the cavity mold surface and the core mold surface when a portion of the cavity contact surface and a portion of the core contact surface are in contact.   
   
   
       13 . The injection mold assembly of  claim 12 , wherein the second portion comprises a high heat transfer material and defines a significant portion of the cavity mold surface. 
   
   
       14 . The injection mold assembly of  claim 12 , wherein the first portion of the cavity section forming the contact surface comprises steel and the second portion is formed of comprises beryllium coated with a hardened metal. 
   
   
       15 . A mold assembly having a core member, the core member comprising:
 an upper core section; and   a lower core section configured to generally mate with the upper core section, the upper core section and the lower core section forming a generally smooth core mold surface when attached to each other;   wherein the lower core section comprises a high heat transfer material.   
   
   
       16 . The mold assembly of  claim 15 , wherein the upper core section and the lower core section comprise concentric mating surfaces to facilitate attachment to each other. 
   
   
       17 . The mold assembly of  claim 15 , further comprising a solder to join the upper core section and the lower core section. 
   
   
       18 . The mold assembly of  claim 15 , wherein the high heat transfer material comprises beryllium or copper. 
   
   
       19 . The mold assembly of  claim 15 , further comprising an internal core tube positioned within both the upper core section and the lower core section, the internal core tube configured to deliver cooling fluid to the lower core section. 
   
   
       20 . A mold for manufacturing preforms, comprising:
 a cavity section; and   a core section comprising a core member and a core holder, the core holder being configured to concentrically surround and support the core member;   wherein the core holder comprises a core contact surface that is configured to contact a cooperating contact surface when the cavity section and the core section mate to form a mold cavity therebetween; and   wherein the core contact surface comprises a hardened material.   
   
   
       21 . The mold of  claim 20 , wherein the cooperating contact surface is positioned on the cavity section. 
   
   
       22 . The mold of  claim 20 , wherein the cooperating contact surface is positioned on a thread finish portion, the thread finish portion generally located between the cavity section and the core section. 
   
   
       23 . The mold of  claim 20 , wherein the core member comprises a high heat transfer material. 
   
   
       24 . The mold of  claim 20 , wherein the core member and the core holder comprise cooperating tapered portions. 
   
   
       25 . The mold of  claim 20 , wherein the core member comprises at least one internal cooling fluid channel. 
   
   
       26 . A method of forming a preform, comprising:
 providing a core section comprising a core contact portion and a core member;   providing a cavity section comprising a cavity contact portion and a main portion;   providing a mold cavity between the core section and the cavity section;   wherein the cavity contact portion and the core contact portion comprise a hardened material, the cavity contact portion being configured to contact the core contact portion when the cavity section and the core section mate;   wherein at least one of the core member and the main portion of the cavity section comprises a fluid channel;   injecting a moldable material into the mold cavity; and   allowing the moldable material to at least partially cool into a preform; and   moving the core section away from the cavity section in order to remove the preform.   
   
   
       27 . The method of  claim 26 , wherein the main portion of the cavity section comprises a high heat transfer material. 
   
   
       28 . The method of  claim 26 , wherein the core member comprises a high heat transfer material. 
   
   
       29 . The method of  claim 26 , further comprising delivering a cooling fluid through the fluid channel. 
   
   
       30 . A method of forming a preform, comprising:
 providing a core section having a core contact surface comprising a hardened material;   providing a cavity section comprising an upper portion and a lower portion, the upper portion comprising a hardened material and having an upper contact surface configured to mate and contact the core contact surface, and the lower portion comprising a high heat transfer material;   providing a mold cavity between the core section and the cavity section; and   injecting a moldable material into the mold cavity.   
   
   
       31 . A preform formed by the process comprising:
 providing a cavity section having a first portion and a second portion, the first portion comprising a hardened material that at least partially defines a cavity contact surface, the second portion comprising a high heat transfer material and at least partially defining a cavity mold surface;   providing a core section having a core contact surface and a core mold surface, at least a portion of the core section forming the core contact surface comprising a hardened material; and   providing a mold cavity having a distal end and a proximal end and generally defined between the cavity mold surface and the core mold surface when a portion of the cavity contact surface and a portion of the core contact surface are in contact, the distal end of the mold cavity formed by the second portion of the cavity section.