Patent Number: 
Section: description

The present invention will now be described in detail with reference to the accompanying drawings. FIG. 5 is a partial side view of an anisotropic diffuser member according to an embodiment of the present invention. FIG. 6 is a front elevation view of a mold member including anisotropic diffuser members according to an embodiment of the present invention. FIG. 7 is a front elevation view of a mold member including anisotropic diffuser members according to an embodiment of the present invention. FIG. 8 is a front elevation view of a mold member including anisotropic diffuser members according to an embodiment of the present invention. The molding apparatus 10 shown in FIG. 1 through FIG. 4 is representative of an applicable mold apparatus and process that may be well suited for the present invention. However, one of skill in the art will appreciate that there are a multitude of molding apparatus 10 and molding processes for which the present invention will be especially advantageous. Further, although a two-part molding member 20 is shown in the accompanying figures, one of skill in the art will appreciate that multi-part molds can be readily employed as desired by the specific molding application. As aforementioned, molding processes often utilize heaters or other methods of temperature control to ensure uniform temperatures within a mold die or mold cavity. However, depending on the placement of the heaters within or along a mold die or mold cavity, there can be dramatic differences in temperatures throughout the mold cavity. The present invention dramatically reduces these thermal gradients that may occur from uneven heating of a mold cavity. The present invention utilizes the unique properties of fiber reinforced composites to uniformly distribute the heat within a mold die during a molding process. Fiber reinforced composites can be designed to more rapidly distribute the heat along the length of the die as opposed to the linear distance between the heater, e.g., a heat rod, and the molded piece. Fiber reinforced composites can be placed along the interior of a mold cavity in the same linear direction as the piece being molded. The fiber reinforced composites can be either of a fiber reinforced composite coating or an actual structural plate, such as a diffuser plate. For example, graphite fiber reinforced composites are ideally suited for the present invention due to their unique thermal properties. The individual fibers can be arranged in a substantially uniform direction, e.g., resembling the grain of a piece of wood. One of skill in the art will appreciate that the individual fibers of a fibrous material, despite being non-linear geometrically, can be arranged so that the lengths of each fiber are generally arranged in parallel to each other. FIG. 5 is a partial side view of an anisotropic diffuser member 100 according to an embodiment of the present invention. The anisotropic diffuser member 100 has individual fibers 101 that are arranged in a uniform manner along the length of each individual fiber in the lay-up. With this type of diffuser member 100, heat will travel significantly faster in the direction of the fibers, e.g. along their length L, than it will through the direction of the lay-up, e.g. directions transverse to the length L of the fibers 101. When heat is applied in the direction of the lay-up, the heat is diffused rapidly along the lengths L of the fibers 101 and travels much slower against the grain of these fibers 101. FIG. 6 is a front elevation view of a mold member 20 including anisotropic diffuser member 100 according to an embodiment of the present invention. A two-part mold member 20 is shown having an upper mold member 21 and a lower mold member. In this embodiment, heat can be applied from any or all directions to the mold member 20 by heaters (not shown, but represented by QIN). If the diffuser members 100 were not used, hot spots would likely develop at the individual points of application of the heat from the heaters QIN. Although the rate of distribution of heat along the diffuser member 100 is typically variant with respect to direction or orientation, these anisotropic diffuser members 100 instead force heat to travel rapidly and uniformly along the length of the fibers. Accordingly, uniform temperature distribution is achieved along the upper and lower surfaces of the mold member 20 shown in FIG. 6. FIG. 7 is a front elevation view of a mold member 20 including anisotropic diffuser members 100 according to an embodiment of the present invention. A pair of anisotropic diffuser members 100 are arranged along a pair of vertical walls of a mold cavity 90 in the mold member 20 shown. If heat were applied along the upper and lower surfaces of the mold member 20 in the embodiment shown in FIG. 7, the vertically arranged diffuser members 100 would ensure that the heat is rapidly transferred along the full length of the mold cavity 90. FIG. 8 is a front elevation view of a mold member 20 including anisotropic diffuser members 100 according to an embodiment of the present invention. In addition to a pair of vertically arranged diffuser members 100, a horizontally arranged diffuser member 100 is also shown. Although a diffuser member is not shown affixed along an upper surface of the mold cavity 90, one of skill in the art will appreciate that this is possible if the diffuser member is formed so as to still permit the introduction of melt into the mold cavity 90 during a molding process, e.g., machined with an inlet hole to match that corresponding to the mold member 20. One of skill in the art will appreciate that any number of diffuser members 100 of a variety of sizes and shapes can be applied to a mold cavity 90 according to the present invention. As long as the diffuser members 100 are selected to impart uniform temperature distribution and still conform to the wide variety of mold cavity geometries possible in the molding art, the operator of the molding process is afforded precise temperature control with easy positioning of the diffuser members 100 as desired. In a preferred embodiment, diffuser members may be approximately 0.5 inches in thickness. However, one of skill in the art will appreciate that the precise dimensions of the diffuser members 100 will depend on the targeted application, e.g., the size and shape of the mold cavity to which it will be applied. Graphite fiber reinforced composites are particularly advantageous due to their unique thermal properties and fibrous internal structure. However, one of skill in the art will appreciate that alternative materials can be incorporated into the present invention, particularly those showing common properties with those specifically listed in the foregoing embodiments. It will be appreciated that many fibrous composites may be advantageously incorporated into the present invention. Any fibrous material having the ability to be manufactured so as to produce a controlled thermal conductivity as a result of the aforementioned fibrous lay-up is applicable to the present invention and the foregoing embodiments. A method according to the present invention will now be described with reference to the accompanying drawings and foregoing description. A method of controlling process temperatures in a molding apparatus 10 includes the steps of controlling a temperature of a mold member 20 with a heat source; and arranging an anisotropic diffuser member 100 along a surface of said mold member 20 for distributing heat uniformly from said heat source along a length of said anisotropic diffuser member 100. The method of controlling process temperatures in a molding apparatus may include a diffuser member 100 having a fibrous reinforced composite with a plurality of fibers each having a respective length L, wherein the fibers 101 are arranged in a lay-up with the length of each fiber 101 arranged in a substantially uniform direction within said diffuser member 100. The diffuser member 100 is arranged in a position permitting a rapid transfer of heat along the length L of each fiber 101. In a preferred embodiment, the fibrous composite is a graphite reinforced composite. The diffuser member 100 can be arranged in a position along an interior surface of a mold cavity 90 of said molding member 20 as seen in FIG. 7 and FIG. 8. Alternatively, the diffuser member 100 can be arranged along an exterior surface of the mold cavity 90 as seen in FIG. 6 or along a combination of both interior and exterior surfaces. The diffuser member 100 may be applied in the form of a diffuser plate or even a permanently applied thermal coating.