Patent Application
20160243739
The present disclosure relates to injection-molding tools.
Automotive components may be produced by injection-molding processes. In conventional injection molding, a resin material is injected into a part cavity defined by a plurality of dies. After molding, the part typically under goes secondary processing, such as painting, film, or plating.
In mold-in-color plastic-injection molding a class “A” finished surface is created during the injection-molding process and secondary processing is not preformed. Because there is no secondary processing, any defects formed during molding of the component cannot be fixed and the component must be scrapped.
According to one aspect of this disclosure, an injection-molding tool includes a first die having a first surface, and a second die having a second surface. The first and second surfaces cooperate to define a part cavity when the tool is closed. The tool also includes at least one jet disposed on the first surface for blowing gas toward the second surface to remove debris from the second surface. The injection-molding tool may include ejector pins extendable out of the first surface for ejecting and trimming an injection-molded part. The at least one jet may be activated subsequent to the actuation of the ejector pins to remove any debris created during trimming of the part.
According to another aspect of this disclosure, a method is disclosed for operating an injection-molding tool. The tool includes first and second dies that each have a tool face. At least one jet is disposed on one of the first and second dies. The method includes the steps of closing the dies to form a part cavity defined by the tool faces, and injecting resin into the cavity. The method further includes cooling the part, opening the cavity allowing removal of the part, and blowing compressed gas through the jets to remove debris from the tool faces. The method may also include the steps of ejecting the part and trimming excess material from the part with one or more ejector pins. The blowing step may be performed after the trimming step.
According to yet another aspect of this disclosure, an injection-molding tool includes a mold cavity having a first tool surface, and a mold core having a second tool surface. The first and second tool surfaces cooperate to at least partially define a part cavity when the tool is closed. A cooling plate is disposed adjacent to the mold cavity on a side opposite the mold core. The cooling plate includes coolant channels. At least one jet is disposed on the second tool surface for blowing gas toward the first tool surface to remove debris from the second surface. The mold core may include ejector pins extendable out of the second tool surface for ejecting a part and trimming runners from the part.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
Referring to
The tool 20 includes a first die (or mold core) 22 and a second die (or mold cavity) 24. The first die 22 includes a tool surface 26 and the second die 24 includes a tool surface 28. The first and second dies 22, 24 are movable relative to each other between an open position (illustrated in
The tool 20 may be configured to produce mold-in-color parts. Mold-in-color parts exit the injection-molding tool with a finished surface and do not require any secondary operations—such as painting or plating. Because mold-in-color parts do not undergo secondary operations, any defects created on the class-A surface during injection molding cannot be fixed and the defective part must be scrapped. To reduce part defects, the tool 20 may include heating elements 44. The heating elements 44 may be disposed in the second die 24 adjacent to tool surface 26, which is the tool surface that forms the class-A surface of the part. The heating elements 44 maintain the tool surface 26 at a temperature near or above the glass transition temperature of the injected resin to prevent premature cooling of the resin as it enters the part cavity 30. This helps to reduce defects formed during injection molding of the part 36. The heating elements 44 may be electric heating elements, or may be heated by other methods, such as steam or gas.
Referring to
At step 110 the part 36 is ejected from the tool 20 by one or more ejector pins 42. As best seen in
The tool 20 includes gas jets 48 for blowing the debris off of one or more of the tool surfaces 26, 28 at step 112. The gas jets 48 are configured to blow compressed gas, such as air, nitrogen, oxygen or any other type of gas. The gas jets 48 may be disposed on the tool surface 26 of the first die 22. The gas jets 48 may be aimed to blow gas at tool surface 28. Each of the gas jets 48 includes a supply line 50 for receiving compressed gas. The supply lines 50 link the jets 48 in fluid flow communication with a compressor 52. The compressor 52 may include a gas storage tank for holding compressed gas. The compressor 52 may be disposed on the first die 22 or may be separate from the tool 20.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.
