Non-limiting embodiments disclosed herein generally relate to injection molding systems and more particularly a melt conditioner for use in an injection molding system.
Molding is a process by virtue of which a molded article can be formed from a molding material by using a molding system. Various molded articles can be formed by using a molding process, such as an injection molding process. An example of a molded article that can be formed, for example, from polyethylene terephthalate (PET) is a preform suitable for subsequent blow molding into a final shaped container.
A typical injection molding system includes (among other things): (i) a melt preparation apparatus, (ii) a clamp assembly, (iii) a mold assembly, and (iv) a melt distributor, e.g. a hot runner.
In the operation of a typical injection molding system, the melt preparation apparatus forces a desired amount of melt (i.e., molten molding material) into a mold cavity of the mold assembly. The melt may enter the mold cavity through a gate via the melt distributor. The melt distributor and the mold assembly are tools that may be sold separately from or together with injection molding systems.
In accordance with an aspect disclosed herein, there is provided a melt conditioner. The melt conditioner includes a melt conditioning body. The melt conditioning body includes a plurality of melt conditioning channels. The melt conditioning channels are located upstream of at least one manifold flow channel. Each melt conditioning channel conveys, in use, a melt sub flow and is dimensioned to provide, in use a conditioned melt sub flow having a thermal profile that accounts for a downstream geometry of the manifold flow channel. The melt conditioning body can be configured to provide a split-conditioned melt flow having an array of thermal profiles embedded therein.
As examples, the melt conditioner may be configured as a machine nozzle of a melt preparation apparatus, a sprue bushing of a melt distributor, or a melt distributor.
These and other aspects and features of non-limiting embodiments will now become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments in conjunction with the accompanying drawings.
The non-limiting embodiments will be more fully appreciated by reference to the accompanying drawings, in which:
The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted.
Reference will now be made in detail to various non-limiting embodiment(s) of a melt conditioner for use in an injection molding system. It should be understood that other non-limiting embodiment(s), modifications and equivalents will be evident to one of ordinary skill in the art in view of the non-limiting embodiment(s) disclosed herein and that these variants should be considered to be within scope of the appended claims.
Furthermore, it will be recognized by one of ordinary skill in the art that certain structural and operational details of the non-limiting embodiment(s) discussed hereafter may be modified or omitted altogether. In other instances, well known methods, procedures, and components have not been described in detail.
Machine nozzles associated with melt preparation apparatuses, and sprue bushings associated with melt distributors, are commonly used in injection molding systems. It is generally known that a melt, typically a molten molding material such as, for example, PET, is not thermally homogeneous as it enters a mold cavity via at least one of a melt distributor (such as a hot runner), a machine nozzle and a sprue bushing. The lack of thermal homogeneity can be attributed to shear heating of the melt as it flows through one or more melt flow channels. The shear heating of the melt creates a non-uniform thermal flow-front having a boundary layer of hot melt adjacent to a surface of the melt flow channel, which surrounds a core of cooler melt at the center of the melt flow channel. Some injection molding systems incorporate a static mixer as a melt conditioner to re-mix this non-uniform thermal flow-front. However, it has been found that static mixers cannot achieve a perfectly uniform thermal flow-front due to inefficiencies in mixing.
In operation, the clamp assembly 904 closes the mold assembly 906 such that the mold cavity 920 is defined. The clamp assembly 904 is configured to apply a clamping force that squeezes the mold assembly 906 together as the mold cavity 920 is injected with the melt from the melt preparation apparatus 902. The melt may enter the melt distributor 922 via a machine nozzle 919. The melt may enter the mold cavity 920 via the melt distributor 922.
The melt conditioning body 110 includes a housing 140 and a flow divider insert 150. The housing 140 defines a melt passageway 142 that conveys melt, when in use, from the upstream end 160 to an outlet 112 at the downstream end 170. As depicted, the melt passageway 142 can be substantially cylindrically shaped. The diameter of the melt passageway 142 may vary along the length of the melt passageway 142.
The flow divider insert 150 is located, at least in part, within the melt passageway 142 of the housing 140 and cooperates therewith to define a plurality of melt conditioning channels 120. The flow divider insert 150 is configured to split, in use, a flow of melt through the melt passageway 142 into a plurality of melt sub flows. The flow divider insert 150 may have a longitudinal axis that is substantially coincident with a longitudinal axis of the melt passageway 142 and/or the housing 140. Furthermore, the housing 140 and the flow divider insert 150 may cooperate to define a recombination chamber 130 leading to the outlet 112. The flow divider insert 150 may be heated by a heating element (not shown) connected to the flow divider insert 150. Likewise, the housing 140 can be heated by a heating element (not shown) connected to the housing 140. As depicted in
The flow divider insert 150 includes an elongated central portion 152. The elongated central portion 152 can be a torpedo-like member. The flow divider insert 150 also includes a plurality of fins 154 extending radially from the elongated central portion 152. The plurality of fins 154 define, at least in part, the plurality of melt conditioning channels 120. As such, each melt conditioning channel 120 has a substantially triangular or sector shaped cross-section.
The flow divider insert 150 may additionally include a flow diverter 156 located upstream of the plurality of fins 154. The flow diverter 156 is configured to facilitate diverting the flow of melt to the plurality of melt conditioning channels 120. As an example and as shown, the flow diverter 156 may be substantially conically shaped.
The flow divider insert 150 may further include a flow recombination guide 158 located downstream of the plurality of fins 154. The flow recombination guide 158 is configured to facilitate combining the plurality of conditioned melt sub flows to produce a split-conditioned melt flow. The flow recombination guide 158 may be substantially conically shaped.
As illustrated, the melt conditioning body 110 may be an assembly of several parts, for example, the housing 140, the elongated central portion 152, the plurality of fins 154, the flow diverter 156, and the flow recombination guide 158 may be made as separate parts, then assembled together. Alternatively, some or all of the melt conditioning body 110 may be integrally formed. For example, some or all of the melt conditioning body 110 may be made using a solid freeform fabrication process (also known as an additive manufacturing process). Solid freeform fabrication (SFF) refers to any one of the techniques in a collection of techniques for manufacturing solid objects by the sequential delivery of energy and/or material to specified points in space to produce that solid. SFF is sometimes referred to as “rapid prototyping,” “rapid manufacturing,” “layered manufacturing,” and “additive fabrication.” It will be appreciated that SFF is sometimes referred to as freeform manufacturing (FFF). The following are a number of typical techniques for SFF: (A) electron beam melting to produce fully fused void-free solid metal parts from powder stock; (B) electron beam freeform fabrication to produce fully fused void-free solid metal parts from wire feedstock; (C) fused deposition modeling, in which hot plastic is extruded through a nozzle to build up a model; (D) laminated object manufacturing in which sheets of paper or plastic film are attached to previous layers by either sprayed glue, heating, or embedded adhesive, and then the desired outline of the layer is cut by laser or knife to produce a finished product that typically looks and acts like wood; (E) laser-engineered net shaping in which a laser is used to melt metal powder and deposit it on the part directly, which has the advantage that the part is fully solid and the metal alloy composition can be dynamically changed over the volume of the part; (F) POLYJET MATRIX™, which enables simultaneous jetting of multiple types of materials; (G) selective laser sintering, which uses a laser to fuse powdered metal, nylon, or elastomer, though additional processing is necessary to produce a fully dense metal part; (H) shape deposition manufacturing in which part and support materials are deposited by a printhead and then machined to near-final shape; (I) solid ground curing, which shines a UV light on an electrostatic mask to cure a layer of photopolymers and uses solid wax for support; (J) stereolithography, which uses a laser to cure liquid photopolymers; (K) three-dimensional printing, which encompasses many technologies of modern 3D printers, all of which use inkjet-like printheads to deposit material in layers and commonly includes, but is not limited to, thermal phase change inkjets and photopolymer phase change inkjets; and/or (L) robocasting, which involves depositing material from a robotically-controlled syringe or extrusion head.
A person skilled in the art will appreciate that the various parts may individually be made of any suitable material(s) and may have any suitable surface finish. According to a non-limiting embodiment, the flow divider insert 150 may include a material having a thermal conductivity that is different from the thermal conductivity of a material included in the housing 140. According to a non-limiting embodiment, the flow divider insert 150 may include a material having a thermal conductivity that is substantially the same as the thermal conductivity of a material included in the housing 140.
The flow divider insert 150 may be aligned in relation or relative to the manifold assembly 924 such that a flow of melt in the manifold flow channel 926, having entered the manifold flow channel 926 via the melt conditioning body 110 has a thermal profile of a predetermined shape that is properly oriented with respect to the split geometry of the manifold flow channel(s) 926 located downstream of the melt conditioning channels 120.
Each melt conditioning channel 120 is configured to impart a thermal profile to a flow of melt conveyed therein. As such, the plurality of melt conditioning channels 120 provide a plurality of conditioned melt sub flows.
Each melt conditioning channel 120 may be uninterrupted, i.e., each melt conditioning channel 120 may be a continuous channel with no splits, mixers or other such features designed to split or otherwise disturb the flow of melt. In addition, each melt conditioning channel 120 of the plurality of melt conditioning channels 120 may be substantially parallel in relation to one another. Furthermore, each melt conditioning channel may have a longitudinal axis that is substantially parallel to a longitudinal axis of the melt conditioning body 110. Alternatively, according to a non-limiting embodiment (not depicted), the plurality of melt conditioning channels 120 or a subset thereof may trace a path of any other suitable course, for example a helical or spiral path between the upstream end 160 and the downstream end 170.
In addition, as depicted, the cross-sectional area of each melt conditioning channel 120 can vary along a length thereof. According to an alternative non-limiting embodiment (not depicted), the cross-sectional area of each melt conditioning channel 120 can be substantially constant along a length thereof. The length of each melt conditioning channel 120 can be greater than its width. Further, the length of each melt conditioning channel 120 is sufficient for conditioning a flow of melt. Each melt conditioning channel 120 is dimensioned (i.e., shaped and sized) to develop a thermal profile or melt thermal flow front that takes into account, and may be optimized to, the geometry of the manifold melt channel(s) 926 located downstream of the melt conditioning channel 120. For example, the thermal profiles of the conditioned melt sub flows can be optimized to take advantage of the split geometries of the manifold flow channel(s) 926 so as to reduce molding material thermal and mass imbalance between mold cavities 920. The thermal profiles of the conditioned melt sub flows may therefore not be thermally uniform, but are predictable or predetermined.
The melt conditioning body 110, as depicted in
As used herein, the term “split-conditioned melt flow” is defined as a melt flow that has been produced by: (i) splitting a flow of melt into a plurality of melt sub flows, (ii) conditioning each melt sub flow such that a thermal profile is imparted thereto; and (iii) recombining the plurality of conditioned melt sub flows into a split-conditioned melt flow having an array of thermal profiles embedded therein.
In this embodiment, the split-conditioned melt flow provided by the melt conditioner 100 is split into a plurality of conditioned downstream melt sub flows by splitting or branching of the intake manifold flow channel 926a into the intermediary manifold flow channels 926b at the first split 186.
The melt conditioner 200 includes a melt conditioning body 210. The melt conditioning body 210 defines a plurality of melt conditioning channels 220. As depicted, each melt conditioning channel 220 is substantially cylindrically shaped having a substantially circular shaped cross-section. Alternatively, one or more of the melt conditioning channels 220 can have an oval cross-section or any other suitably shaped cross-section.
The melt conditioning body 210 also defines a flow diverter 256 at the upstream end 260. In the illustrated embodiment, the flow diverter 256 is integrally formed with the melt conditioning body 210. The melt conditioning body 210 also defines a plurality of melt outlets 212 at the downstream end 270. Each melt conditioning channel 220 is associated with a respective melt outlet 212. In the illustrated embodiment, the melt conditioning channels 220 are uninterrupted and the conditioned melt sub flows are not recombined prior to entry into the melt distributor 922 (
Each of the conditioned melt sub flows are split into a plurality of conditioned downstream melt sub flows by splitting or branching of the intermediary portion 926e of the intake manifold flow channel 926d into the drop manifold flow channels 926f at the first split 296.
However, the melt conditioning body 310 does not include a flow diverter 156, 256 (
Similar to melt conditioner 100, the melt conditioning body 310 also defines a recombination chamber 330 located immediately downstream of the plurality of melt conditioning channels 320. At the downstream end 370, the melt conditioning body 310 includes a flow recombination guide 358, which defines, at least in part, the recombination chamber 330. In use, the plurality of conditioned melt sub flows are combined in the recombination chamber 330 to produce a split-conditioned melt flow, which exits the melt conditioning body 310 via the outlet 312. The split-conditioned melt flow can be split into a plurality of conditioned downstream melt sub flows by the melt distributor 922
However, the melt conditioning body 410 does not include a flow diverter 156, 256 (
The melt conditioning body 510 may be substantially cylindrically shaped and includes a housing 540 and a flow divider insert 550 located within the housing 540. The flow divider insert 550 is similar to the flow divider insert 150 (
The melt conditioner 600 includes a melt conditioning body 610 similar to the melt conditioning body 410 (
It is noted that the foregoing has outlined some of the more pertinent non-limiting embodiments. It will be clear to those skilled in the art that modifications to the disclosed non-embodiment(s) can be effected without departing from the spirit and scope thereof. As such, the described non-limiting embodiment(s) ought to be considered to be merely illustrative of some of the more prominent features and applications. Other beneficial results can be realized by applying the non-limiting embodiments in a different manner or modifying the invention in ways known to those familiar with the art. This includes the mixing and matching of features, elements and/or functions between various non-limiting embodiment(s) is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as those skilled in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise, above. Although the description is made for particular arrangements and methods, the intent and concept thereof may be suitable and applicable to other arrangements and applications.
Filing Document | Filing Date | Country | Kind |
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PCT/US15/11935 | 1/20/2015 | WO | 00 |
Number | Date | Country | |
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61931150 | Jan 2014 | US |