BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a plate-type heat pipe, and more particularly to a method for manufacturing a plate-type heat pipe which has a one-piece outer wall formed by sintering metal powder.
2. Description of related art
Generally, plate-type heat pipes efficiently dissipate heat from heat-generating components such as a central processing unit (CPU) of a computer. Referring to FIGS. 5-6, a conventional plate-type heat pipe comprises a case (not labeled) formed by stamping a metal sheet to have an engaging plate 100 and a base plate 101 defining a trough. The case contains working fluid (not shown) therein. A wick structure 102 is laid on an inner wall of the base plate 101. The base plate 101 and the engaging plate 100 are assembled together by welding. However, airtightness cannot be guaranteed by the welding. Furthermore, the welding operation may harm the wick structure 102, thereby reducing heat transporting capacity of the working fluid and adversely affecting heat conductibility of the plate-type heat pipe.
It is therefore desirable to provide a method for manufacturing a plate-type heat pipe having good heat conductibility and overcoming the limitations described.
SUMMARY OF THE INVENTION
A method for manufacturing a plate-type heat pipe includes deposition of a core of a material releasable by thermal or chemical reaction in the center of a cavity disposed in a mold, filling first and second metal powders in the injection systems of a double-mode injection molder with opposite injection directions, respectively, the first metal powder size exceeding that of the second metal powder. The first and second metal powders are injected into the cavity of the mold, the first metal powder securely adhering to the core and the second metal powder securely adhering to the first metal powder, thereby obtaining a green piece. The green piece is removed from the mold and the core removed therefrom by thermal or chemical reaction, thereby defining a space in the green piece. The green piece is heated to obtain a sintered product with a tight outer wall constituting the sintered second metal powder and a wick structure constituting the sintered first powder. Finally a working fluid is injected into the space, and the opened ends of the sintered product are vacuumed and sealed, producing the final product.
Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIG. 1 is a cross-sectional view showing a plate-type heat pipe in accordance with a first embodiment of the present invention to be formed in a mold.
FIG. 2 is a cross-sectional view of a green piece for forming the plate-type heat pipe in accordance with the first embodiment of the present invention, wherein the green piece is removed from the mold of FIG. 1.
FIG. 3 is a cross-sectional view of a plate-type heat pipe in accordance with a second embodiment of the present invention.
FIG. 4 is a cross section of the plate-type heat pipe of FIG. 3, taken along line VI-VI thereof.
FIG. 5 is an exploded, cross-sectional view of a related plate-type heat pipe.
FIG. 6 is an assembled view of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1-2, a method for manufacturing a plate-type heat pipe 30 in accordance with a first embodiment of the present invention comprises deposition of a core 20 of a material releasable by thermal or chemical reaction into a cavity (not shown) of a mold 10, filling the cavity, injecting a first metal powder with particle diameter from 50 μm to 150 μm and a second metal powder with particle diameter from 10 μm to 20 μm, respectively into two injection systems with opposite injection directions of a double-mode injection molder (not shown), utilizing the double-mode injection molder to inject the first and second metal powders into the cavity of the mold 10, such that the first metal powder securely adheres to the core 20 and the second metal powder securely adheres to the first metal powder, thereby providing a green piece, removing the green piece from the mold and removing the core 20 from the green piece by thermal or chemical reaction, thereby defining a chamber 35 in the green piece, heating the green piece at a high temperature to obtain a sintered product with a tight outer wall 31 constituting the sintered second metal powder and a wick structure 33 constituting the sintered first metal powder, injecting a working fluid (not shown) such as water, alcohol, methanol, or the like into the chamber 35, evacuating by vacuum the sintered workpiece, and sealing the ends of the sintered workpiece to obtain the final product.
The core 20 is a high polymer or waxy material. After the core 20 is removed, the green piece defines the chamber 35 to receive the working fluid (not shown) therein. In this embodiment, the wick structure 33, formed integrally, can transport the working fluid continuously.
Referring to FIGS. 3 and 4, a method for manufacturing a plate-type heat pipe 40 in accordance with a second embodiment of the present invention comprises deposition of a core (not shown) in a cavity of a mold (not shown) wherein the core defines a number of vertical holes therethrough, the holes being arranged in a matrix consisting of three rows and six columns, filling the cavity of the mold, injecting a first metal powder with particle diameter from 50 μm to 150 μm and a second metal powder with particle diameter from 10 μm to 20 μm, respectively into two injection systems with opposite injection directions of a double-mode injection molder (not shown), utilizing the double-mode injection molder to inject the first and second metal powders into the cavity of the mold such that a part of the first metal powder fills the vertical holes of the core and another part of the first metal powder securely adheres to the core and the second metal powder securely adheres to the another part of the first metal powder, thereby obtaining a green piece, removing the green piece from the mold and removing the core from the green piece by thermal or chemical reaction, defining a chamber 45 in the green piece by the removed core, heating the green piece at a high temperature to obtain a sintered workpiece with a tight outer wall 41 constituting sintered second metal powder, a wick structure 43 constituting sintered first metal powder, and eighteen supporting portions 47 also constituting sintered first metal powder, injecting a working fluid (not shown) such as water, alcohol, methanol, or the like into the chamber 45, evacuating by vacuum the sintered workpiece, and sealing the ends of the sintered workpiece to obtain the final product.
In this embodiment, there are eighteen supporting portions 47 disposed in the chamber 45 formed by removing the core from the green piece. The supporting portions 47 are parallel to each other and connect with top and bottom ends of the wick structure 43 to enhance the stability of the plate-type heat pipe 40. The supporting portions 47 include a plurality of pores which communicate with the pores of the wick structure 43. Thus, the working fluid returns to the bottom of the tight outer wall 41 of the plate-type heat pipe 40 from the wick structure 43 and the supporting portions 47 when the plate-type heat pipe is in use and vapor condenses into liquid in the top of the tight outer wall 41.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
Patent Application
20100028192
