Molding Apparatus with Combined Core Plunger/Ejector and Methods Therefor

Abstract

A molding apparatus for injection molding or compression molding includes an “A” portion of a mold, a “B” portion of the mold, and at least one core plunger/ejector. The core plunger/ejector provides dual functionality, wherein it participates in molding operations by consolidating a feed material in the mold cavity, and also is responsible for separating the part from various mold surfaces and ejecting it from the mold.

Claims

1. A molding apparatus for molding a part, comprising: an A-portion of a molding apparatus; a B-portion of a molding apparatus, at least one of the A-portion or the B-portion is movable to open and close the molding apparatus; and a core plunger/ejector, wherein the core plunger/ejector is movable to: (a) form a sealed cavity, in conjunction with the A-portion and the B-portion, in which charge is received; (b) consolidate the charge in the cavity to a shape of the part; (c) break a bond formed between the part and the core plunger/ejector; and (d) break a bond formed between the part and at least one of the A-portion or the B-portion of the molding apparatus.

2. The molding apparatus of claim 1 wherein the core plunger/ejector advances to form the sealed cavity.

3. The molding apparatus of claim 2 wherein the core plunger/ejector advances to consolidate the charge.

4. The molding apparatus of claim 3 wherein the core plunger/ejector retracts to break the bond between the part and the core plunger/ejector.

5. The molding apparatus of claim 4 wherein the core plunger/ejector advances to break the bond between the part and at least one of the A-portion or the B-portion of the molding apparatus.

6. The molding apparatus of claim 1 wherein the molding apparatus is a compression molding apparatus.

7. The molding apparatus of claim 1 wherein the molding apparatus in an injection molding apparatus.

8. A method for molding a part via a molding apparatus that comprises three discrete mold portions including a top portion, a bottom portion, and a core plunger/ejector, the method comprising: advancing the core plunger/ejector to consolidate a charge disposed in a cavity, wherein the cavity is formed, collectively, by the top portion and the bottom portion of the molding apparatus; cooling the molding apparatus to form the part; opening the molding apparatus; moving the core plunger/ejector to break a bond between the part and the core plunger/ejector; and moving the core plunger/ejector to break a bond between the part and the top portion or the bottom portion of the molding apparatus.

9. The method of claim 8 wherein moving the core plunger/ejector to break a bond between the part and the core plunger/ejector comprises retracting the core plunger/ejector.

10. The method of claim 8 wherein moving the core plunger/ejector to break a bond between the part and the top portion or the bottom portion of the molding apparatus comprises advancing the core plunger/ejector.

11. The method of claim 8 wherein the charge is injected under pressure into and through a sprue, and from the sprue to the cavity.

12. The method of claim 8 wherein the charge, in the form of fiber-bundle preforms, is placed in the cavity.

13. A molding apparatus for molding a part, comprising: a top, A-portion of the molding apparatus; a bottom, B-portion of the molding apparatus, at least one of the A-portion or the B-portion movable to open and close the molding apparatus; and a core plunger/ejector, wherein the core plunger/ejector is movable to: (a) consolidate a charge into a geometry of the part; and (b) eject the part.

14. The molding apparatus of claim 13 wherein the molding apparatus is a compression molding apparatus.

15. The molding apparatus of claim 13 wherein the molding apparatus in an injection molding apparatus.

16. A molding apparatus for molding a part, the molding apparatus comprising upper and lower mold halves, a portion of which upper and lower mold halves collectively function to form to molding cavity, and a core plunger/ejector that is movable to apply pressure to a charge in the molding cavity, and eject the part after the part is molded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1A depicts a conventional injection-molding system, including an ejection system, wherein the ejection system is in an unactuated state.

[0043] FIG. 1B depicts the conventional injection-molding system of FIG. 1A, wherein the ejection system is fully actuated thereby removing a finished part from the mold.

[0044] FIGS. 2A-2C depict a part that is to be made using a compression molding apparatus that includes a core plunger/ejector in accordance with an illustrative embodiment of the present invention.

[0045] FIGS. 3A-3F depict, via a sectional view of, a sequence of operations for making the part of FIGS. 2A-2C using a compression molding apparatus including a core plunger/ejector.

[0046] FIG. 4 depicts a perspective view of a portion of the compression molding apparatus depicted in FIGS. 3A-3F.

DETAILED DESCRIPTION

[0047] FIGS. 2A-2C depict a part—a frame for ski goggles—that is made by an improved compression-molding apparatus that includes a core plunger/ejector, in accordance with an illustrative embodiment of the invention.

[0048] FIG. 2A depicts a perspective view of frame 240 for the ski googles. FIG. 2B depicts a front view of frame 240, and FIG. 2C depicts a sectional view of frame 240 through the line A-A in FIG. 2B and in the direction shown.

[0049] FIGS. 3A through 3F depict a molding sequence for forming frame 240 of FIGS. 2A through 2C, as illustrated by the relative positions of the three major portions of compression-molding apparatus 300. The portions of apparatus 300 are shown via sectional views for clarity. FIG. 4 depicts a perspective view of compression-molding apparatus 300 (to supplement the sectional views depicted in FIGS. 3A-3F), wherein the configuration of apparatus 300 depicted in FIG. 4 (as a function of depicted progress of the molding sequence) corresponds to FIG. 3C.

[0050] FIG. 3A depicts a sectional view of compression-molding apparatus 300. Apparatus 300 includes “A” portion 350 (identified within dashed lines), “B” portion 356, and core plunger/ejector 360 (identified within dashed lines). Other elements of apparatus 300, such as an actuator to move core plunger/ejector 360 “upwards” or “downwards,” are not depicted in the figures to maintain a focus on elements that are most germane to an understanding of the invention. These three portions—A portion 350, B portion 356, and core plunger/ejector 360—are depicted in perspective in FIG. 4. The various unidentified channels and openings that appear in FIG. 4, which for the most part do not appear in FIGS. 3A-3F, are for purposes of tool machinability or mold operability. As to the latter, such channels and openings are used for thermocouple placement, as a heater-cartridge housing, for mold assembly, for mold fixation to a press, etc. These channels and openings are not germane to an understanding of the invention and, consequently, will not be described in further detail.

[0051] In FIG. 3A, compression-molding apparatus 300 is “open,” such that A-portion 350 and B-portion 356 are separated from one another. In this state, core plunger/ejector 360 is in a retracted state. Charge 370 of resin or resin/fiber has been placed on surface 364 of core plunger/ejector 360.

[0052] FIG. 3B depicts molding apparatus 300 with the cavity in a sealed state (although the mold itself is not necessarily closed), wherein surface 352 of A-portion 350 and surface 358 of B-portion 356 abut one another, forming parting line 382. Moreover, sealed cavity 384 is formed the abutment of various surfaces of A-portion 350, B-portion 356, and core plunger/ejector 360 with one another. Charge 370 is within sealed cavity 384. After the mold is closed, A-portion 350, B-portion 356, and core plunger/ejector 360 are heated to the processing temperature, which causes the resin in charge 370 to melt.

[0053] In FIG. 3C, core plunger/ejector 360 is advanced (i.e., moved upwards in the figure), consolidating the charge into the final shape of frame 240. Movement of core plunger/ejector 360 to its final position creates additional tooling interfaces; namely, interface 386 between B-portion 356 and core plunger/ejector 360, and interface 388 between A-portion 350 and core plunger/ejector 360. After a dwell (e.g., typically a few minutes) at the processing temperature, mold apparatus 300 starts cooling, and cools until an ejection temperature is reached.

[0054] In FIG. 3D, mold apparatus 300 is opened. With the upward movement of A-portion 350 to open the mold, the bond between the A-portion and the finished part—frame 240 (shown in section, as in FIG. 2C)— is broken.

[0055] In FIG. 3E, core plunger/ejector 360 is retracted (i.e., moves downward in the figure), breaking the bond between the molding surface of the core plunger/ejector and the finished part (frame 240). In FIG. 3F, core plunger/ejector 360 is once again advanced, breaking the bond between the bottom surface of frame 240 and the upper surface of A-portion 356, ejecting the part.

[0056] It is notable that the aforementioned sequence of operations is permutable. For example, the operation depicted in FIG. 3E can be performed before the operation depicted in FIG. 3D.

[0057] In the embodiment of molding apparatus 300 depicted in the figures, A-portion 350, B-portion 356, and core plunger/ejector 360 are symmetric about a vertical center line. However, the overall mold is not necessarily symmetric about all axes, nor is symmetry a requirement of embodiments of the invention. Furthermore, although the illustrations in FIGS. 3A-3F depict a specific cross section for frame 240, embodiments of the invention can be used to make parts having any cross-sectional geometry, which, in fact, can even vary along the part being fabricated.

[0058] In the illustrative embodiment depicted in FIGS. 3A-3F, core plunger/ejector 360 actuates in the Z direction (the vertical direction in the figure). As the sequence shows, the core plunger/ejector operates by first consolidating the resin or resin/fiber charge to finalize part geometry, and then ejects the part after the charge is solidified to a finished part.

[0059] It will be appreciated that the continuous surface of the core plunger/ejector 360 supports a finished part for ejection in a way that ejector pins cannot. In fact, since the surface of the core plunger/ejector provides much of the surface that serves as a molding cavity, it necessarily perfectly conforms to much of the shape of the finished part. Thus, virtually all of the concerns related to ejection pins are avoided by the use of the core plunger/ejector in accordance with the present teachings.

[0060] It is to be understood that the disclosure describes a few embodiments and that many variations of the invention can easily be devised by those skilled in the art after reading this disclosure and that the scope of the present invention is to be determined by the following claims.