Low pressure dynamic molding system utilizing multiple accumulators and inline polymer modification

Abstract

A molding system and method are provided in which an extruder supplies molten polymer to at least two temperature-controlled accumulators through a polymer diverter valve. A controller coordinates accumulator filling and discharge with press cycling to execute a two-stage profile. The system supports inline addition of compatibilizers or flame-retardant additives and is suitable for molding recycled polymers from Automotive Shredder Residue (ASR) and post-consumer waste.

Description

LOW PRESSURE DYNAMIC MOLDING SYSTEM UTILIZING MULTIPLE ACCUMULATORS AND INLINE POLYMER MODIFICATIONPRIOR RELATED APPLICATION DATA

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 708,712, filed October 17, 2024, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] This application relates to molding processes, specifically to methods of low pressure dynamic molding that incorporate extrusion use multiple accumulators, inline polymer modification, and automated temperature and pressure controls.BACKGROUND

[0003] Conventional compression molding commonly relies on manual placement of polymer charges (“pucks,” preforms, or hand-laid mats). Variability in puck mass, geometry, and preheat history produces non-uniform melt temperatures and viscosity across the charge. Operators may stage preforms on ambient fixtures while presses open, allowing skins to cool and oxidize; when compressed, these colder regions create weld / cold flow lines, knit lines, and un-melted inclusions. Hand placement also introduces positional error relative to the cavity center, ribs, or bosses, yielding asymmetric flow fronts, trapped air, and voids. For fiber-filled compounds, inconsistent charge thickness and shear history drive local orientation differences and fiber breakage, creating weak spots and scatter in mechanical performance. Moisture and volatiles are difficult to control with manual handling, especially for hygroscopic or recycled feeds, further contributing to porosity and surface defects. On the equipment side, press cycle time is often poorly coupled to the upstream extruder; when the press is not ready, the extruder must idle, purge, or interrupt flow, which induces thermal excursions, oxidative degradation, and gel formation in the barrel. Stop-start operation also produces pressure surges and die drool, lowering throughput and increasing scrap. Accumulator heads or cut-and-carry strategies mitigate some timing mismatch but still depend on manual puck cutting, transfer, and placement, preserving many sources of variability.

[0004] Injection molding can intentionally “overpack” regions to reduce sink and improve surface fidelity, but doing so for large, thick- section, or highly filled parts demands high clamp tonnage, extended hold times, and substantial specific energy per kilogram. Long cooling times drive cycle inefficiency and can lock in residual stresses and anisotropy from high shear during gate entry. Gate freeze-off in thick sections limits how effectively pressure is transmitted for consolidation, forcing larger gates, hot runners, or multiple gates that add knit lines and complexity. For abrasive, glass- or mineral -filled streams, screw and barrel wear as well as hot-runner maintenance add cost. Structural-foam variants (e.g., physical or chemical foaming) improve cavity fill and reduce clamp force, but introduce cell-structure variability, swirl marks, and property gradients that are not always acceptable for structural or appearance-critical parts. Moreover, injection-centric systems are not optimized for steady-state, continuous processing of mixed or recycled polymer feeds whose composition, melt index, and contamination levels vary over time; maintaining stable shot size, screw recovery, and pack profiles with such feeds typically requires tight incoming-material control or dedicated conditioning steps that increase capital and operating expense.

[0005] Recycled streams such as automotive shredder residue (ASR) and post-consumer plastics (e g., MRF bales, curbside films, mixed rigids) frequently contain incompatible polymer phases — non-polar polyolefins (PE / PP) mixed with polar styrenics (PS / ABS / SAN), PET / PBT, PA, PVC, and thermoplastic elastomers — as well as residual fillers (talc, CaCCh, glass), fines, labels, and rubbers. Differences in polarity, viscosity, softening point, and melt elasticity lead to coarse phase separation, droplet coalescence, and poor interfacial adhesion in the absence of compatibilization, producing low tensile and impact strength, brittle fracture, and poor environmental stress-crack resistance. Legacy additive packages and flame retardants can further complicate rheology and stability, while trace PVC or halogens can catalyze degradation in polyesters and polyolefins. Washing and sorting operations reduce contamination but can be water-intensive and energy-intensive; residual moisture and surfactants contribute to voids and splay during molding. Repeated thermal histories (grinding, extrusion, re-melt) induce chain scission in polyolefins, lowering molecular weight, increasing MFR, and embrittling the material unless chain-extension or stabilization strategies are applied. Material fractions can phase-separate or degrade, creating gels and surface defects that are difficult to suppress with conventional batch compounding alone.

[0006] Accordingly, there is a need for a molding platform that can maintain continuous extrusion while presses cycle, can automate deposition of uniform, large charges at controlled temperature,can provide dynamic two-stage molding including intentional overfill / overpack, and can enable inline reactive compatibilization to tailor mechanical and flame-retardant properties in real-time.SUMMARY

[0007] This application relates to low pressure dynamic molding systems and methods that integrate continuous extrusion, multiple accumulators, dynamic pressure control, and inline polymer modification to produce consistent, high-strength molded parts from virgin or recycled polymers, including Automotive Shredder Residue (ASR) blends.

[0008] The disclosed system enables continuous extrusion during press cycling, eliminating downtime and manual charge placement. Molten polymer from an extruder is directed through a polymer diverter valve into temperature controlled accumulators, which alternately fill and discharge through polymer diverter values into a press mold via heated conduits and nozzles. A controller coordinates valve timing, temperature regulation, and a two stage pressure cycle — a first, low-pressure spreading phase followed by a rapid, high-pressure consolidation.

[0009] Inline polymer modification can allow for real-time compatibilization and catalytic copolymerization of mixed polymers using titanate, zirconate, or aluminate agents, improving adhesion and mechanical performance. The system can feed multiple presses from a single extruder while maintaining melt uniformity (AT < 5 °C), thereby increasing throughput and efficiency.

[0010] Hydraulic bladder tanks provide second-stage pressures, while independent temperature control of mold halves ensures even curing and dimensional stability. The process can accommodate overfill, achieving injection-molding-like density and strength at lower cost. The architecture is scalable, energy efficient, and well suited to recycled polymer feedstocks.

[0011] One aspect includes a molding system having an extruder, at least two accumulators, and a polymer diverter valve configured to alternately route molten polymer between accumulators while a controller executes a two stage pressure cycle comprising a low pressure spread and a high pressure consolidation.

[0012] Another aspect includes a method of low pressure dynamic molding that continuously extrudes polymer, buffers the polymer flow in accumulators, automatically deposits a uniform charge through a heated nozzle, and performs a two stage pressure to achieve uniform flow anddensity. In an example, the method can allow overfilling of the mold, a process that mimics the overpacking capabilities of injection molding but at a lower capital cost.

[0013] Another aspect includes introducing molten polymer through multiple heated nozzles positioned at top, side, and bottom mold entry points to enhance distribution and eliminate flow defects.

[0014] Another aspect includes a system wherein a single large extruder continuously feeds multiple presses via accumulators, maintaining consistent melt temperature while each press cycles independently.

[0015] Another aspect includes an automated deposition system that meters and deposits uniform polymer charges from accumulators to the mold cavity, improving repeatability.

[0016] Another aspect includes independently temperature-controlled mold halves, each having closed-loop feedback to maintain a target setpoint and ensure even polymer curing.

[0017] Another aspect includes maintaining continuous extrusion while pressing cycle, thereby preventing material degradation and improving process efficiency.

[0018] Another aspect includes a two-stage pressure profile with a first-stage range of about 0- 1000 psi (e g., 100-600 psi, 200-800 psi, or 300-900 psi) for spreading and a second-stage range of about 900-3000 psi (e.g., 1200-1900 psi, including 1400-1600 psi), optionally with a 10-500 ms ramp.

[0019] Another aspect includes accumulator-based thermal control maintaining melt temperature within a narrow range to minimize viscosity fluctuation and orientation defects.

[0020] Another aspect includes inline polymer modification during continuous extrusion, enabling real-time compatibilization and property adjustment without interrupting production.

[0021] Another aspect includes injecting titanate, zirconate, or aluminate catalysts inline to promote copolymerization and improve adhesion between dissimilar polymers such as PE, PP, HIPS, and AB S.

[0022] Another aspect includes an additive-injection port within the extruder and static mixer upstream of the accumulators for on-the-fly adjustment of formulation and catalyst concentration.

[0023] Another aspect includes an overfill control system configured to introduce 1 to 50 % excess charge to increase part density and eliminate voids.

[0024] Another aspect includes introducing polymer from multiple entry points (top, side, bottom) to accommodate different part geometries and fill characteristics.

[0025] Another aspect includes automated ejection of the molded part following completion of the second pressure stage, minimizing cycle time.

[0026] Another aspect includes inline compatibilization by adding reactive agents upstream of the accumulators to enhance blend uniformity in ASR-derived polymers.

[0027] Another aspect includes processing post-consumer or ASR-derived polymers containing mixed polymer phases to form high-quality, specification-controlled products.

[0028] Another aspect includes operating two or more presses in parallel from a single extruder using synchronized accumulator discharge to maximize throughput.

[0029] Another aspect includes maintaining line pressure of about 100 to 900 psi during first-stage spreading for efficient charge flow.

[0030] Another aspect includes controlling mold-half temperatures within ±5 °C, providing consistent curing and dimensional accuracy across molded parts.BRIEF DESCRIPTION OF THE FIGURE

[0031] FIG. 1 shows a schematic extrusion-accumulator-press architecture with a diverter valve, controller, heated conduits, and multiport nozzle.

[0032] FIG. 2 shows a press topology fed via a heated manifold and multiple accumulators.

[0033] FIG. 3 illustrates accumulator internals.

[0034] FIG. 4 shows a mold with multiport heated inlets at the side, top, and bottom, and independent mold halves.

[0035] FIG. 5 illustrates a two stage pressure profde (pressure versus time) with stage annotations and ramp timing.

[0036] FIG. 6 schematically illustrates a diverter valve positioned upstream and downstream of the accumulators.

[0037] FIG. 7 shows an exemplary plant-level layout illustrating an embodiment of the system.DEFINITIONS

[0038] The term “ASR” denotes automotive shredder residue and blends derived therefrom following separation (e.g., flotation), size reduction, and melt processing.

[0039] The term “accumulator” means a vessel configured to receive molten polymer from an extruder, store the polymer under controlled temperature and pressure, and discharge a measuredcharge into a mold. The term “additive” refers to a modifier introduced into a polymer to alter or improve one or more of its physical properties.

[0040] The term “inline polymer modification” includes addition of reactive compatibilizers, catalysts, or additives (including flame-retardant (FR) packages) directly to the molten stream during continuous operation, upstream of the accumulators.

[0041] The term “flame retardants” means agents that inhibit or delay the combustion of thermoplastics by chemical and physical processes. Flame retardants are additives that can be mixed into thermoplastics to make them more resistant to burning by increasing ignition resistance, reducing flame spread, or suppressing smoke and dripping. Common flame retardants include phosphorus-based systems (e.g., phosphates, phosphonates), inorganic systems (e.g., aluminum and magnesium hydroxides), and intumescent systems (e.g., glass-forming additives, zinc borate, and nanoclays), which can work through mechanisms such as forming an insulating char layer or releasing water to cool the material. The choice of flame retardant can depend on the specific thermoplastic, application, economic factors, and regulatory compliance. Examples include zinc borate, glass-forming agents, and nanoclays. Examples further include flame retardant systems containing phosphorus and / or nitrogen compounds that enhance char generation.

[0042] The terms “overfill” or “overpack” mean depositing a total polymer mass exceeding the nominal cavity volume requirement such that the second-stage pressure can consolidate material, reduce voiding, and improve density uniformity.

[0043] The term “polymer” means a macromolecular compound prepared by polymerizing monomers of the same or different type. The term “polymer” includes homopolymers, copolymers (including block and random), polymers with three or more monomers, interpolymers, and so on.

[0044] The term “recycle” refers to processing an item so that its constituent materials can be recovered and reused in the manufacture of new products. When post-consumer waste is converted into raw materials rather than being disposed of as solid waste, the resulting material can be referred to as “post-consumer recycled” material.DETAILED DESCRIPTION

[0045] This application discloses a low pressure dynamic molding system that can use continuous or discontinuous extrusion with multiple accumulators to enhance efficiency, precision, and the quality of molded parts. The system can automate deposition of a uniform, large polymer chargeinto the mold cavity. The use of multiple accumulators can help maintain consistent polymer temperature, reducing defects such as cold-flow lines and variable orientation that can weaken parts. Dynamic pressure control through a two stage pressure cycle can optimize polymer flow, while automated temperature control of the mold halves can ensure even polymer solidification. Additionally, inline polymer modification can allow real-time adjustment of polymer properties, such as compatibilization of mixed polymers with catalysts including zirconium, titanate, or aluminates, enabling production of parts with varying characteristics from a single setup. The system can improve part consistency, can enhance physical properties, and can increase production efficiency by feeding multiple presses with minimal temperature loss and by ensuring uniform polymer distribution. By using multiple accumulators, the system can provide more continuous flow from the extruders even during filling, enhancing production efficiency and consistency.

[0046] In one embodiment, the polymers may be obtained by processing automotive shredder residue (ASR), post-consumer waste, wide-spec material, or virgin polymer feedstocks (or combinations of the same) to yield high-quality, uniform blends of polyethylene (PE), polypropylene (PP), or combinations thereof. The process can include flotation separation, shredding, direct extrusion, catalytic polymer property modification, and continuous molding, while minimizing environmental impact by reducing water consumption and eliminating extensive washing. Through catalytic repolymerization, the system can enhance the physical properties of dissimilar polymer blends recovered from ASR. Additives, including flame-retardant (FR) additives, can be used to modify the polymer to meet desired end-use physical properties.

[0047] FIG. 1 schematically illustrates a low pressure dynamic molding system (100) configured to decouple continuous extrusion from discontinuous press cycles. The system can include a controller (103), and an encoder (104), a continuous extruder (105), one or more accumulators (120), a polymer diverter valve (135, 136), heated conduits (132) terminating at a heated nozzle (125) that delivers melt into a mold (140) carried by a press (not shown) with upper and lower mold halves (144, 146), and a stroke / position encoder (107) providing feedback to the controller. The extruder (105) can continuously deliver molten polymer to the diverter valve (135). The diverter valve can selectively direct the melt to a chosen accumulator (120) for fdling while allowing another accumulator to discharge, thereby maintaining uninterrupted extruder operation. Each accumulator (120) can be temperature controlled and sized to hold a measured charge of molten polymer, which is discharged to another diverter valve (136). In specific embodiments,accumulators can include a level sensor (124) and a pressure sensor (126), and can employ a discharge valve or a ram / piston to meter the charge. While two accumulators (120) are depicted for clarity, any number greater than one can be used.

[0048] From the selected accumulator, the melt can travel through heated conduits (132) that can maintain a substantially uniform temperature profile to the heated nozzle (125). The heated nozzle can be positioned at a mold entry location (e.g., side entry as shown; top and / or bottom entries can be used in other figures) and can automatically deposit a uniform charge into the mold cavity between the mold halves.

[0049] The press (140) can carry the upper mold half (144) and lower mold half (146). The halves can be independently temperature controlled to reduce thermal gradients during spreading and consolidation. After charge deposition via the nozzle (125), the press can execute a two stage cycle (low-pressure spread followed by a rapid high-pressure surge) as described elsewhere in this specification.

[0050] The controller (103) can coordinate valve timing, accumulator fill / discharge, conduit and mold temperatures, and the two stage press profile. A stroke / position encoder (107) (e.g., a linear scale or rotary encoder) can provide real-time feedback of platen position and / or velocity, enabling synchronization of charge deposition and stage transitions. Additional sensor inputs (e.g., 124, 126) can close the loop on mass, pressure, and temperature control.

[0051] In operation, the extruder (105) can continuously supply melt; the diverter valve (135) can route flow to an accumulator (120) while another accumulator (120) discharges through conduit (132) and nozzle (125) to the mold (140). The controller (103) can use encoder (104) feedback to initiate the first pressure stage as the mold closes, then can command the second-stage surge to complete fill and densify the part. The cycle can repeat with the accumulators alternating roles, preserving melt-temperature uniformity and throughput.

[0052] FIG. 2 schematically illustrates a production line in which a single continuous extruder (105) can supply melt to multiple accumulators (120) that, in turn, can feed a plurality of presses (140) in parallel. The extruder (105) can continuously discharge molten polymer to the accumulators (120) through a diverter. Each accumulator can be temperature controlled and sized to hold a measured charge for its assigned press. Internal level / pressure instrumentation and discharge valves can be provided. Downstream of the accumulators or bank of accumulators can be a heated manifold that can maintain the melt within a temperature band. From the manifold,heated branch conduits (162) can route the charge to the respective presses. Insulation and zoned heaters (not separately numbered) along the conduits can minimize heat loss and can help maintain AT control between the extruder outlet and each press inlet. Each press (140) can carry a mold having an upper mold half (144) and a lower mold half (146). At each tool, the branch conduit can terminate in one or more heated nozzle (134) positioned to introduce the charge into the cavity. A diverter valve (130) and associated isolation valves can be used upstream to sequence which accumulator can be filled and which can be discharging. While an accumulator (120) can discharge through a branch (162) to a press (140) via a nozzle (134), other accumulators (120) can be filling from the extruder, thereby maintaining throughput and uniform melt temperature across tools. Charge mass balance and temperature setpoints can be coordinated to keep charge to charge variation (e.g., about 2% or less) and inlet AT (e.g., about 5 °C or less) within target limits. In some embodiments, a screen changer is disposed between the extruder and the accumulators to remove contaminants or control melt filtration.

[0053] FIG. 3 illustrates accumulator internals, including a temperature-control heater bands, a level sensor (124), pressure sensors (126), and a discharge valve (128), which can control the material flow toward a press or during purging. A piston or ram (129) can meter and expel a measured charge through the bottom discharge valve (128) into a heated conduit. The level sensor (124) and pressure sensor (126) can provide real-time feedback to the controller for fill, hold, and discharge sequencing. During filling, a diverter valve can route extruder flow into the vessel while valve (128) remains closed and the piston retracts. During discharge, the controller can open valve (128) and advance the piston to deliver a uniform charge to the mold via the conduit. The accumulator may also include a pressure-relief valve (141).

[0054] FIG. 4 illustrates a mold with an upper half (144) and lower half (146) defining a cavity (142). Molten polymer can be delivered through heated conduits (132) terminating at heated nozzles (134). Side, top, and bottom nozzle placements can enable multi-port introduction into the cavity. The configuration can promote uniform charge spread, minimize cold flow lines, and ensure complete fill. Each mold half can be independently temperature controlled to maintain a tight setpoint band. Selected ports can be actuated based on geometry and stage of the two stage pressure cycle.

[0055] In one embodiment, a method for continuous low pressure dynamic molding using multiple accumulators can include several steps. First, polymer material can be extruded from alarger extruder and stored in multiple accumulators. These accumulators with a purge valve can help ensure continuous polymer flow, which can be automatically deposited into the mold cavity. The process can feature a two stage presure cycle with dynamic pressure control: the first stage can apply pressure between 100 and 900 psi to spread the polymer charge, followed by a rapid second-stage pressure of 900 to 3,000 psi to complete mold filling. The molten polymer can be introduced into the mold through heated nozzles located at the sides, top, and bottom of the mold, ensuring even distribution. Automated temperature control of the mold halves can maintain optimal conditions for polymer flow and curing, while overfill capabilities can improve part density and structural integrity. Finally, the molded part can be ejected, yielding a consistent, high-quality product with enhanced mechanical properties. This method can streamline the molding process, can reduce defects, and can allow inline polymer modifications. The process can feature a two-stage pressure cycle with dynamic pressure control: the first stage applies about 0- 1000 psi (e g., 100-600 psi, 200-800 psi, or 300-900 psi) to spread the polymer charge, followed by a rapid second-stage pressure of about 900-3000 psi with a 10-500 ms ramp to complete mold filling. In some examples, the line pressure during the first stage can be about 100-400 psi. FIG. 5 illustratively can plot a two-stage pressure profile (pressure vs. time), not to scale. Stage 1 can apply about 0-1000 psi for about 0.1-20 s. Stage 2 can apply about 900-3000 psi with a 10-500 ms ramp and a 0.01-5 s dwell.

[0056] In certain embodiments, the first stage of compression molding can be conducted at a relatively low pressure, for example less than about 1000 psi (optionally less than about 1200 psi, 900 psi, or 800 psi), such as within about 100-600 psi, 200-800 psi, or 300-900 psi, for about 0.1- 20 seconds to promote uniform flow and spreading of the molten charge. The second stage can then be carried out at a higher pressure, for example less than about 3000 psi (optionally less than about 2000 psi or 1500 psi), such as within about 900-1500 psi, 1000-1800 psi, or 1200-1900 psi, with a controlled pressure ramp of about 10-500 milliseconds to complete densification and achieve full cavity fill while minimizing flash, voids, and thermal degradation.

[0057] The pressure range in both the first and second stages of the molding process can be adjusted based on specific part requirements. In the first stage, pressure can vary between 200 and 1200 psi, 200 to 1000 psi, 600 to 1000 psi, and 700 to 950 psi. Similarly, in the second stage, the pressure can range from 1000 to 3000, 2000 to 6,000 psi, 2000 to 5,000 psi. The timing of the first stage can also be varied to optimize the molding process, ranging from 1 millisecond to 1,000milliseconds. Narrower time ranges for the first stage can include 1 to 15 seconds, 2 to 20 seconds, and 5 to 10 seconds, depending on polymer flow characteristics. In the second stage, the time can vary from 1 to 5 seconds, with narrower time ranges including 10 milliseconds to 2 seconds, 20 milliseconds to 1.5 seconds, and 1 to 30 milliseconds, providing further control over polymer molding and curing. This flexibility can allow the process to be fine-tuned for different polymer types and part geometries. Additional pressure can be provided through the use of a bladder tank.

[0058] Specific embodiments can provide a low pressure dynamic molding system that can incorporate multiple accumulators to deliver a continuous or discontinuous extrusion of polymer into the mold, eliminating manual placement of polymer charges. Such embodiments can minimize temperature variations and can allow precise control over polymer flow and orientation. Such embodiments can include automated temperature control of the mold halves, inline polymer modification, dynamic pressure control, and improved compatibility between different polymer types.

[0059] Compatibilizers (e.g., titanate) can be added to improve the final molded product. Compatibilizers are additives used to enhance compatibility between two or more polymers that are otherwise immiscible or have poor adhesion when blended. In certain embodiments, titanates can facilitate covalent coupling between dissimilar polymer phases, forming a true copolymer and minimizing both phase separation and additive migration. In polymer blends, different polymers often do not mix well due to differences in chemical structure, leading to phase separation and poor mechanical properties. Reactive compatibilizers can function by forming random and / or block copolymers that enhance impact modification, reduce interfacial tension, and improve adhesion between different polymer phases. Titanate, zirconate, and aluminate coupling agents can also form a monomolecular layer on fillers present in ASR, enhancing dispersion and adhesion. This bridging effect can also bind residual rubber to the polymers, further improving recycling efficiency. This catalyst system can be effective not only for olefinic systems but also for styrenic polymers (HIPS, ABS) and some engineering grade polymers such as nylons and polyesters. Reacting olefinic ASR with titanates and metallic hydroxides can create formulations that pass UL-94 flame tests (see U.S. Pat. Nos. 4,525,494; 5,753,853; 6,197,135). Admixing ASR with titanates in an extruder can yield ethylene / propylene rubber, useful for increasing low-temperature flexibility of other polymers (see U.S. Pat. No. 4,657,988). Utilizing multiple accumulators connected via a “polymer diverter valve” can enable continuous extruder operation even withdiscontinuous molding processes (compression, injection, structural foam). This can maximize extruder efficiency and molding press time by ensuring a readily available polymer supply.

[0060] In one embodiment, the system can utilize multiple accumulators to help ensure continuous polymer flow into the mold cavity, eliminating interruptions and inconsistencies typical in traditional systems. The accumulators can store the polymer and can discharge it automatically into the mold, allowing larger polymer charges to be deposited rapidly without manual intervention. This can lead to a uniform flow of material into the mold, which can enhance the mechanical properties and reliability of the final molded parts. The use of accumulators can also ensure that the polymer remains at an optimal temperature during the molding process, further improving part consistency and quality. The automated deposition of large polymer charges can be implemented by using, for example, 2, 3, 4, or 9 accumulators, enabling the system to handle and deliver larger charges efficiently. In one example, there can be two or more accumulators. A single accumulator can be used if the operator accounts for continuous extruder flow while injecting the charge. This can be accomplished through the use of a 3-way valve.

[0061] In one embodiment, multiple accumulators can allow precise and automated deposition of large polymer charges into the mold cavity. The automated deposition system can help reduce human error, ensuring uniformity in each polymer charge. This automation can reduce cycle times, can increase throughput, and can enhance overall part quality and performance.

[0062] In one embodiment, the system can reduce temperature variation common in traditional molding, particularly when hand-laid polymer charges are used. Such variations can cause cold-flow lines and inconsistent polymer orientation, leading to weak points in the final product. The present system can address this by maintaining consistent polymer temperature through multiple accumulators. The accumulators can store polymer in a controlled environment before it is discharged into the mold cavity. Additionally, automated temperature control of the mold halves can ensure uniform flow and can minimize temperature gradients, resulting in parts with superior mechanical properties, increased strength, and reduced occurrence of defects.

[0063] In one embodiment, the system can incorporate automated temperature control for each mold half, continuously monitoring and adjusting temperature in real time. This can ensure that the polymer remains at an optimal temperature during the entire molding process, promoting consistent flow and proper curing. By maintaining ideal temperature conditions, the system can help prevent issues such as cold-flow lines, uneven shrinkage, or incomplete mold filling. Theprecise temperature management enabled by this system can enhance dimensional stability and overall part quality.

[0064] In one embodiment, the system can be equipped with a larger extruder which, in conjunction with multiple accumulators, can enable continuous feeding of polymer material to multiple presses without compromising quality. The accumulators can store polymer at a consistent temperature, ensuring it can be ready for immediate delivery to the mold cavities. This configuration can allow higher production throughput, as several presses can be operated simultaneously without the risk of temperature loss or polymer degradation. The combination of a larger extruder and accumulators can ensure that the polymer remains at the optimal processing temperature, resulting in consistent, high-quality parts across multiple presses.

[0065] In one embodiment, the system can enable inline polymer modification and compatibilization, a process that would typically be interrupted in traditional molding due to the need to stop the extruder during press operation. Continuous extrusion, facilitated by multiple accumulators, can allow uninterrupted compatibilization. This capability can enable real-time modification of polymer properties, allowing production of parts with varying physical characteristics, such as flame retardant (FR) or non-FR properties. The system can also introduce catalysts such as zirconium, titanate, and aluminates, which can allow copolymerization of mixed polymers, resulting in improved strength, durability, and other enhanced mechanical properties in the final parts.

[0066] In one embodiment, the system can feature dynamic pressure control using a two stage pressure cycle for optimal polymer flow and part quality. The first stage can apply pressure between 0 and 900 psi to bring the mold halves together, ensuring the polymer charge can be spread evenly across most of the mold cavity. In the second stage, a rapid high pressure surge of 900 to 3,000 psi can be applied within 500 milliseconds, completing the filling process. This two stage cycle can allow precise control over polymer flow rate, ensuring the mold can be fully filled, minimizing air pockets, and reducing formation of cold-flow lines. The result can be a high quality part with consistent polymer flow and enhanced mechanical properties. Dynamic pressure control with a two stage process can allow the high hydraulic flow rates (GPM) required for rapid polymer press out. This system can minimize defects caused by polymer cooling too quickly, ensuring more consistent and uniform molding results.

[0067] FIG. 5 schematically illustrates a hydraulic circuit configured to drive the press actuator during the two stage pressure cycle. Flow from a hydraulic pump can pass through a servo or proportional valve to the press cylinder, with pressure and flow setpoints commanded by the controller for precise control. A bladder tank can be tee-connected to the pressure line to provide surge capacity and energy storage. During the rapid second-stage ramp, the pre-charged bladder can release hydraulic fluid to meet instantaneous flow demand, thereby smoothing transients and minimizing pressure ripple or overshoot. During low-demand intervals, the tank can refill, stabilizing the first-stage spread pressure and reducing pump load. Optional check valves, relief valves, and pressure transducers (not shown) can protect the circuit and provide closed-loop feedback. This arrangement enables fast, repeatable pressure ramps while maintaining stable hydraulic conditions at the press, with a uniform and repeatable pressure-time profile.

[0068] FIG. 6 schematically illustrates a diverter valve positioned upstream and downstream of the accumulators, thereby regulating flow to the accumulators. An inlet port can receive a continuous stream of molten polymer from the extruder (105), while two outlet ports can direct the melt through heated conduits (132) to respective accumulators (120). A secondary diverter valve (136) can control material flow from the accumulator(s) (120) to the press or presses (P). The controller can actuate the valve so that the selected flow path is opened while the non-selected path remains closed, allowing one accumulator to fill while the other discharges. This configuration can maintain continuous extrusion, stabilize melt temperature, and coordinate accumulator fill and discharge sequencing.

[0069] In specific embodiments, the molding process can be fully automated under a controller that can execute a recipe-based sequence coordinating all subsystems end-to-end: the extruder can be run continuously with zoned temperature and speed control; the polymer diverter valve and accumulators can be sequenced for fill / hold / discharge based on level and pressure feedback; heated conduits and the heated nozzle can be maintained within set temperature bands for uniform charge delivery; mold-half temperatures can be regulated in closed loop; the press can be driven through a two-stage profile using stroke / position feedback from the encoder and hydraulic surge stabilization via a bladder tank; overfill can be applied and relieved according to programmed displacement / pressure limits; inline additive or compatibilizer dosing (where used) can be metered during continuous extrusion; and part ejection can be triggered automatically upon completion of the second stage and cooling dwell time. Interlocks, alarms, and fault recovery can be implementedso that melt flow, temperature, and pressure windows can be enforced without operator intervention, thereby eliminating manual charge placement, avoiding extruder stoppage during press cycling, and enabling consistent, repeatable production across one or multiple presses.

[0070] In one embodiment, the system can introduce the molten polymer charge into the mold cavity via heated nozzles located at the sides, top, and bottom of the mold. This design can ensure even polymer distribution throughout the cavity, reducing the risk of incomplete fdling or uneven material placement. The side and bottom introduction method, similar to structural foam (SF) polymer feed systems, can enhance overall consistency and part quality. By introducing the polymer from multiple points, the system can ensure uniform material distribution, reducing defects and improving structural integrity. Molten polymer can also be introduced from the top, the bottom, the front, or the back.

[0071] In one embodiment, the dynamic pressure control system can allow overfilling of the mold, a process that mimics the overpacking capabilities of injection molding but at a lower capital cost. Overfilling can ensure that the mold can be completely filled and that the final part can have uniform density and consistent mechanical properties. This capability can be particularly valuable in applications that require high-strength parts with minimal voids. By overpacking the mold, the system can produce parts with enhanced structural integrity, making it an efficient and cost-effective solution for high-performance applications.

[0072] In one embodiment, a hydraulic bladder tank can be utilized to manage surge capacity effectively. The bladder tank can act as a pressure-regulating device, storing excess fluid when demand can be low and releasing it when demand increases, thereby smoothing pressure fluctuations. This can help maintain system stability, can reduce the risk of pressure surges, and can ensure consistent flow in hydraulic systems. By incorporating a bladder tank, the system can respond dynamically to varying operational loads, enhancing overall efficiency and protecting components from wear caused by sudden pressure changes.

[0073] FIG. 7 illustrates an exemplary layout of a representative system (220). As shown, feed material (F) can be delivered to an extruder (210), which continuously supplies molten polymer to a central accumulator bank or set of accumulators (230). From this bank, heated transfer lines can deliver the molten polymer to local accumulators (240) positioned at individual molding units (molds not shown). Each molding unit can include a press cylinder (260), and bladder tanks (230) can be operatively connected to the cylinders through hydraulic lines to provide surge capacity forrapid second-stage pressure. Hydraulic lines (280) can also actuate mold closure. The press (250) is depicted without a mold for clarity. This configuration decouples continuous extrusion from press cycling while maintaining melt-temperature uniformity and hydraulic stability throughout the system. Another embodiment includes a control system for a molding cell, comprising one or more processors and memory storing executable instructions that, when executed, cause the system to: operate an extruder to discharge molten polymer continuously; alternately route the molten polymer to at least two accumulators via a polymer diverter valve while coordinating discharge from another accumulator; maintain temperature setpoints for accumulators and conduits; deposit a measured charge from an accumulator into a mold via a heated nozzle; and drive a press according to a two-stage pressure profde including a first lower-pressure stage and a second higher-pressure stage. The instructions can use feedback from a stroke / position encoder and pressure sensors to achieve a second-stage pressure ramp within 10-500 ms. The instructions can maintain melt AT < 5 °C from an extruder outlet to a mold inlet and maintain a charge-mass tolerance of ±2%. The instructions can adjust inline additive dosing in real time to switch between flame-retardant and non-flame-retardant formulations without stopping the extruder.

[0074] In certain embodiments, alternative polymer feed systems may be employed. For example, the polymer charge could be introduced through a top-entry system or through multiple entry points to accommodate complex part geometries. Another alternative embodiment includes the use of multiple extruders in tandem with accumulators, allowing for the simultaneous production of different types of polymer parts, further increasing throughput and flexibility. Additionally, other catalysts, such as organometallic compounds such as alkali, transition, and post transition metals, could be integrated into the inline modification process to enhance polymer to improve performance characteristics like heat resistance and impact strength. Finally, the system can be adapted to molds of various geometries, enabling the production of parts with intricate internal structures and designs, making it a versatile and efficient solution for a wide range of manufacturing applications.

[0075] While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions, and subcombinations thereof. It is therefore intended that the following appended claims and claimshereafter are interpreted to include all such modifications, permutations, additions, and subcombinations as are within their true spirit and scope.

Claims

CLAIMS1. A molding system comprising: an extruder configured to continuously discharge molten polymer; at least two accumulators fluidly coupled to the extruder, each accumulator including temperature control and a discharge mechanism configured to deliver a measured charge to a mold; a polymer diverter valve configured to alternately route molten polymer from the extruder to selected accumulators while another accumulator discharges; at least one heated conduit terminating in at least one heated nozzle positioned at a mold entry location; and a controller operatively coupled to a press and configured to execute a two-stage pressure profile having a first stage at a lower pressure and a second stage at a higher pressure to complete filling, wherein the controller coordinates filling and discharge of the accumulators such that the extruder operates continuously during press cycling.

2. The system of claim 1, wherein the at least one heated nozzle is positioned at two or more of: a side, a top, and a bottom of the mold cavity.

3. The system of claim 1, further comprising overfill control configured to deliver a charge exceeding a theoretical cavity volume by 1 to 50%.

4. The system of claim 1, wherein temperature controls are configured to maintain a melt temperature difference AT < 5 °C between an extruder outlet and a mold inlet.

5. The system of claim 1, wherein an upper mold half and a lower mold half each include an independent temperature-control loop maintaining a setpoint within ±5 °C.

6. The system of claim 1, wherein each accumulator comprises a level sensor and a pressure sensor, and the controller schedules fill or discharge based on signals therefrom.

7. The system of claim 1, wherein the polymer diverter valve comprises a three-way valve.

8. The system of claim 1, wherein the controller synchronizes initiation of the first stage using feedback from a stroke / position encoder.

9. The system of claim 1, wherein the first stage is performed at about 0-1000 psi for about 0.1-20 s, and the second stage is performed at about 900-3000 psi with a pressure ramp of 10-500 ms.

10. The system of claim 1, further comprising an additive-injection port upstream of the accumulators and a mixer downstream of the injection port.

11. The system of claim 10, wherein the additive comprises a compatibilizer selected from titanates, zirconates, and aluminates.

12. The system of claim 1, wherein the extruder or an associated additive feeder is configured to introduce one or more additives selected from zinc borate, clays, and flame-retardant additives into the molten polymer prior to delivery to the accumulators, and wherein the system maintains the additives in a dispersed state throughout accumulator filling and discharge to produce molded articles having enhanced flame resistance and thermal stability.

13. The system of claim 1, wherein the molten polymer comprises a recycled feed selected from Automotive Shredder Residue (ASR).

14. The system of claim 1, wherein the molten polymer comprises post-consumer waste plastics, the recycled feed including one or more of polyethylene (PE), polypropylene (PP), high- impact polystyrene (HIPS), and acrylonitrile-butadiene-styrene (ABS).

15. The system of claim 1, wherein the controller is configured to automatically: (i) operate the extruder and maintain zone temperature setpoints; (ii) actuate the polymer diverter valve and schedule accumulator fill / hold / discharge based on signals from accumulator level and pressure sensors; (iii) regulate temperatures of the accumulators, heated conduits, and upper andlower mold halves; (iv) meter and deposit a measured charge via the heated nozzle; (v) drive the press through the first and second stages using feedback from a stroke / position encoder and pressure sensors; and (vi) initiate part ejection upon completion of the second stage, whereby continuous extrusion and molding proceed without manual charge placement during normal operation.

16. A method of molding comprising: continuously extruding a molten polymer from an extruder; buffering the molten polymer in at least two accumulators while the extruder operates continuously during press cycling; automatically depositing a measured charge from an accumulator into a mold cavity through a heated nozzle; and operating a press according to a two stage pressure profile including a first stage at a lower pressure to spread the charge and a second stage at a higher pressure to complete filling.

17. The method of claim 16, wherein the extruding, buffering, depositing, and two-stage pressing steps are automatically executed by a controller that: (a) receives feedback from accumulator level and pressure sensors, melt and mold temperature sensors, and a stroke / position encoder; (b) actuates a polymer diverter valve to alternate accumulator filling while another accumulator discharges; (c) regulates accumulator, conduit, and mold-half temperature setpoints; and (d) commands part ejection after the second stage, such that no manual charge placement is performed between successive cycles.

18. The method of claim 16, further comprising feeding two or more presses in parallel from the extruder via the accumulators.

19. The method of claim 16, wherein line pressure during at least a portion of the second stage is 1600 psi.

20. The method of claim 16, wherein line pressure during at least a portion of the first stage is 100 to 1000 psi.

21. The method of claim 16, wherein molten polymer is introduced through multiple heated nozzles positioned at two or more of: a side, a top, and a bottom of the mold.

22. The method of claim 16, further comprising controlling temperatures of upper and lower mold halves within ±5 °C of their setpoints.

23. The method of claim 16, further comprising inline compatibilization by adding a catalyst selected from titanates, zirconates, and aluminates upstream of the accumulators and mixing the catalyst into the molten polymer.

24. The method of claim 16, wherein the molten polymer comprises a post-consumer or ASR-derived blend including PE and / or PP with dissimilar polymer phases.

25. The method of claim 16, further comprising using a hydraulic bladder tank hydraulically coupled to a press actuator to smooth a second-stage pressure surge.

26. The method of claim 16, wherein the extruding, buffering, depositing, and two-stage pressing steps are automatically executed by a controller that: (a) receives feedback from accumulator level and pressure sensors, melt and mold temperature sensors, and a stroke / position encoder; (b) actuates a polymer diverter valve to alternate accumulator filling while another accumulator discharges; (c) regulates accumulator, conduit, and mold-half temperature setpoints; and (d) commands part ejection after the second stage, such that no manual charge placement is performed between successive cycles.

27. The method of claim 16, further comprising ejecting the molded part and alternating accumulator roles without interrupting extrusion.

28. The method of claim 16, The method of claim 18, further comprising introducing one or more additives selected from zinc borate, clays, and flame-retardant additives into the molten polymer during extrusion, such that the additives are uniformly dispersed prior to accumulation and molding, whereby the resulting molded article exhibits improved flame retardancy and char-layer formation.

29. The method of claim 16, wherein the molten polymer is derived from recycled Automotive Shredder Residue (ASR) and post-consumer plastic waste, and comprises mixed polymer fractions including polyethylene, polypropylene, and styrenic resins.

30. A manufacturing line comprising: an extruder; at least two accumulators fluidly coupled to the extruder; a heated manifold and heated branch conduits that distribute molten polymer from the accumulators to at least two molding presses; and a controller configured to schedule accumulator fill / discharge and to coordinate delivery of measured charges to the presses while the extruder operates continuously, wherein the controller is further configured to execute a two-stage pressure profile at each press.

31. The manufacturing line of claim 30, wherein a melt temperature difference from the extruder outlet to a farthest press inlet is < 5 °C.

32. The manufacturing line of claim 30, wherein a charge-mass variation among the presses is within ±2%.

33. The manufacturing line of claim 30, wherein each press includes at least one heated nozzle at a mold entry location, optionally multi-port at two or more of: a side, a top, and a bottom.

34. The manufacturing line of claim 30, wherein the heated manifold and heated branch conduits are insulated and zoned-heated.

35. The manufacturing line of claim 30, further comprising an inline additive or catalyst injection station upstream of the accumulators and a static mixer downstream.

36. The manufacturing line of claim 30, wherein each press actuator is associated with a hydraulic bladder tank sized to meet a specified second-stage pressure ramp rate37. The manufacturing line of claim 30, configured to process ASR-derived polymer blends.

38. A control system for a molding cell, comprising one or more processors and memory storing executable instructions that, when executed, cause the system to: operate an extruder to discharge molten polymer continuously; alternately route the molten polymer to at least two accumulators via a polymer diverter valve while coordinating discharge from another accumulator; maintain temperature setpoints for accumulators and conduits; deposit a measured charge from an accumulator into a mold via a heated nozzle; and drive a press according to a two stage profile including a first lower-pressure stage and a second higher-pressure stage.

39. The control system of claim 38, wherein the instructions use feedback from a stroke / position encoder and pressure sensors to achieve a second-stage pressure ramp within 10- 500 ms.

40. The control system of claim 38, wherein the instructions maintain melt AT < 5 °C from an extruder outlet to a mold inlet and maintain a charge-mass tolerance of ±2%.

41. The control system of claim 38, wherein the instructions adjust inline additive dosing in real time to switch between flame-retardant and non-flame-retardant formulations without stopping the extruder.

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