Metal founding – Process – Shaping a forming surface
Patent
1996-07-08
1999-03-02
Batten, Jr., J. Reed
Metal founding
Process
Shaping a forming surface
164 46, 164 98, 164132, 428553, 428554, 428614, 428937, B22D 1900, B22D 2300
Patent
active
058758305
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the production of at least partially metallic articles, and in particular to the production of such articles with defined heat transfer channels.
2. State of the Art
Articles such as dies, moulds and other tools are typically required to operate within a specific temperature range in order to ensure that the operation for which they were designed proceeds smoothly and produces an optimised product. Examples of this are plastic injection moulding (PIM) techniques where it may be desirable to hold the dies at a temperature of, for example, 100.degree. C. As a further example, in the case of high pressure die casting (HPDC) techniques using aluminium alloys, a preferred temperature range may be 200.degree.-250.degree. C.
In both examples the injected material is at a higher temperature than the mould or die. The mould or die cools the injected material until it becomes substantially solid after which the product is ejected. In the process of cooling the injected material the mould or die becomes relatively hotter and must then be allowed to cool (or be artificially cooled) to return to the required operational temperature range.
To reduce cycle times, and therefore increase production efficiency, it is preferable to cool mould or dies during or after use by means of in-built heat transfer channels for cooling water to circulate within the mould or die. Typically, cooling channels such as these are made by drilling into the mould or die block during manufacture and fitting connections for the circulation of cooling water or, in some cases, cooling air. The construction of such cooling channels involves complex, accurate and expensive drilling and plugging of many channels.
In other embodiments it is envisaged that it may be desirable to transfer heat to the article, in which case heating fluid may be passed through the heat transfer channels.
SUMMARY OF THE INVENTION
An improved process for the production of metallic articles having heat transfer channels has now been devised.
According to a first aspect, the present invention provides a process for producing an at least partially metallic article, the process comprising solidification of molten metallic material about pre-formed heat transfer channel defining means to form a solidified metallic deposit provided with heat transfer channel means.
The heat transfer channel means may comprise one or more cavities, ducts, voids, or the like of a variety of shapes or configurations. In certain embodiments, channel means of geometric shape, such as substantially circular, triangular or rectangular cross section is preferred.
An article produced in accordance with the first aspect of the invention is characterised by heat transfer channel defining means of a first microscopic structure being embedded in a solidified metallic deposit of a second microscopic structure. It is believed that an article so characterised is novel and inventive per se and accordingly comprises a second aspect of the invention.
The process is particularly suitable for forming articles for use in moulding or casting. In particular, the process may be used in the manufacture of moulds, dies, cores and other tools for use in moulding or casting of plastics or metallic products, such as for example high pressure die casting (HPDC) using aluminium alloys, or plastics injection moulding (PIM). Preferably the heat transfer channel means comprises cooling channel means through which a coolant fluid may pass.
Desirably, the heat transfer channel defining means is metallic and preferably follows a heat transfer path through the deposit between an inlet and an outlet. Typically for moulds and dies the heat transfer path (and therefore preformed channel defining means) comprises substantially parallel lengths arranged to carry heat transfer fluid in opposed directions. Preferably, the heat transfer path defined is serpentine.
In a first embodiment, it is preferred that the pre-formed channel defining means comprises at le
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Abstract of Japanese Patent Publication 59-27765 Published Feb. 14, 1984.
Jordan Richard Michael
Roche Allen Dennis
Singer Alfred Richard Eric
Batten, Jr. J. Reed
Gallagher Thomas A.
Gordon David P.
Jacobson David S.
Sprayforming Developments Limited
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