Roller pump apparatus and method of processing a material

Abstract

Roller pumps are described for processing polymer, food, and other materials wherein the feedstock may contain a variety of solids and liquids, including mixtures thereof, and at a variety of temperature, pressures, and flow rates. Each roller pump apparatus includes a series dynamically formed entrapped volumes that become progressively smaller from its inlet to its outlet. The dynamically formed entrapped volumes are designed to allow unprocessed material to be reprocessed. Pumps may be designed with balanced or unbalanced rotors, and multiple pump stages can be defined with progressively smaller volumes and tighter clearances to efficiently process material with increasing density and pressure. A roller pump design is also described that is used with a feed screw to provide positive displacement control suitable for use in extrusion, molding, and other material processing applications.

Description

ROLLER PUMP APPARATUS AND METHOD OF PROCESSING A MATERIALCROSS REFERENCE TO RELATED APPLICATIONThis application claims priority to U.S. Provisional Patent Application No. 63 / 600,939, filed on November 20, 2023, the contents of which is hereby incorporated by reference in its entirety.BACKGROUND

[0001] Pumps are widely used for materials conveyance and processing, with gear pumps and vane pumps being two of the most common types. Gear pumps provide relatively smooth flows even at high pressures, but can be costly to purchase, operate, and maintain, especially when handling abrasive materials. Vane pumps, while capable of delivering higher output flow rates and operating at high speeds, can suffer from decreased efficiency, wear, and damage under higher pressures or with abrasive fluids. Roller vane pumps, a variation of traditional vane pumps, incorporate rollers in the vane slots to roll along the pump chamber wall, reducing friction and wear to enhance robustness. However, roller vane pumps are disadvantaged by their size, complexity, and associated costs. The described invention is motivated to provide a simpler, more compact, and cost-effective pump capable of operating at high speeds and pressures using a wide variety of materials.

[0002] Extruders with feed screws are commonly used to process and dispense materials. However, the output flow rate, temperature, and homogeneity of the processed material are not well controlled as a function of screw rotation. To address this issue, practitioners often used longer screws, typically twenty to thirty times the screw’s outer diameter, and incorporate metering pumps to enhance flow rate control. Although this combination achieves acceptable performance in most cases, the resulting systems are large, complex, and costly, both in terms of initial purchase and ongoing operation due to inefficiencies from heat transfer losses to the environment.

[0003] Consequently, it would be advantageous to provide a simpler, more compact, and cost-effective extruder capable of operating efficiently at high speeds and pressures using a wide range of materials.SUMMARY

[0004] An aspect of the present disclosure is a roller pump apparatus comprising: a housing comprising a pump cavity defined by an outer wall and having an inlet and an outlet; a rotor mounted within the pump cavity, wherein the rotor comprises a plurality of lobes; a plurality of rollers, wherein each roller is disposed between adjacent lobes of the rotor, andwherein the number of rollers is equal to the number of lobes; wherein the outer wall of the pump cavity, the plurality of lobes, and the plurality of rollers are configured to form a dynamically changing entrapped volume that varies with rotation of the rotor; wherein rotation of the rotor drives material from the inlet to the outlet of the pump cavity.

[0005] Another aspect is a method of processing a material, the method comprising: providing the roller pump apparatus; supplying the material to an inlet of the roller pump apparatus; and driving the material from the inlet to an outlet of the roller pump apparatus by rotation of the rotor.

[0006] Another aspect is a method for polymer processing, the method comprising: providing the roller pump apparatus; supplying a polymer composition to an inlet of the roller pump apparatus; and driving the polymer composition from the inlet to an outlet of the roller pump apparatus by rotation of the rotor.

[0007] The above described and other features are exemplified by the following figures and detailed description.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The following figures are exemplary embodiments wherein the like elements are numbered alike.

[0009] FIG. 1 A depicts a top view of a roller pump housing with the inlet and one of the rollers shown along with section line B-B.

[0010] FIG. IB depicts a cross-sectional view along section B-B of FIG. 1A illustrating an elliptical cavity and a co-axial rotor having four lobes, which drive four rollers to force material from an inlet to an outlet.

[0011] FIG. 1C depicts an isometric view of the dynamically enclosed volume near the outlet shown in FIG. IB.

[0012] FIG. 2 A depicts a roller pump assembly having two roller pump stages according to an aspect.

[0013] FIG. 2B shows a first roller pump stage of the assembly of FIG. 2A having four rollers.

[0014] FIG. 2C shows a second roller pump stage of the assembly of FIG. 2 A having eight rollers.

[0015] FIG. 3 illustrates a roller pump with an elliptical cavity and a co-axial rotor with four lobes that drive four rollers, forcing material from two inlets to two corresponding outlets.

[0016] FIG. 4 depicts a set of balanced roller pump designs, each with identical ellipsoidal cavity dimensions and rotor outer diameter, but with a varying number of rollers,ranging from four to nine.

[0017] FIG. 5 presents an analysis of the output flow rates as a function of rotor angle, corresponding to the designs of FIG. 4 and data of Table 2.

[0018] FIG. 6 A illustrates a design of stacked roller pump stages within a converging cavity provided within a single housing.

[0019] FIG. 6B illustrates a top view of the first stage rotor with section line C-C.

[0020] FIG. 6C illustrates the section C-C of FIG. 6B of a stacked rotor assembly on a DD shaft (a shaft with flats on opposite sides).

[0021] FIG. 7 shows an isometric view of an extruder integrating the roller pump assembly and a feed screw.

[0022] FIG. 8 depicts a cross-section of a roller pump design with an optional transition rotor and collector shown in FIG. 7.

[0023] FIG. 9 provides modeled and observed flow rates for the designs depicted in FIG. 2 and FIG. 7.

[0024] The drawings and additional tables detailed herein underscore various objects, features, and advantages of the disclosure. Features are not necessarily to scale, with emphasis instead placed on illustrating the embodiments, principles, and concepts of the invention.DETAILED DESCRIPTION

[0025] Through design, modeling, and validation of different screw and metering pump designs, the present inventor has found that the convergence of moving surfaces in many pumps provides compression of the dynamically formed entrapped volumes and, thus, more direct working and processing of feedstock material than the helical channels of conventional screws. However, given the relatively small size of pumps, the present disclosure describes the use of successive stages of pumps in which the material is processed and reprocessed with progressively higher compression ratios and tighter clearances. A roller pump design is described that has a very compact form with excellent flow and wear properties. The multi-stage roller pump according to the present disclosure can find applications in 3D printing by material extrusion, and in general material processing of polymers, pharmaceuticals, foods, fluids, and blends, among others.

[0026] The designs generally provided herein include a first embodiment demonstrating a pump having a lobed rotor with four rollers driving material from one inlet to a series of opposing outlets. A second embodiment includes two pumping stages wherein the outlet of the first stage provided by the first embodiment feeds the inlet of a second pump stage having a lobed rotor with eight rollers and driving processed material to a discharge. A third set ofembodiments provide a balanced rotor design having two or more lobes driving material from two opposing sets of inlets and outlets. A fourth embodiment includes two or more pumping stages in a single housing having a converging set of pump cavities located eccentric to the centerline of the rotors. A fifth embodiment includes a balanced roller pump integrated with a feed screw. The underlying theory, methods of their design and use, and validation results are also described.

[0027] Accordingly, an aspect of the present disclosure is a roller pump apparatus. The roller pump apparatus comprises a housing. The housing comprises a pump cavity which is defined by an outer wall and has an inlet and an outlet. In some aspects, the pump cavity can be an eccentric pump cavity. In some aspects, the pump cavity can be an elliptical pump cavity. Other pump cavity shapes are also contemplated by the present disclosure.

[0028] A person having ordinary skill in the art, guided by the present disclosure, can select a suitable number of inlets and outlets. In some aspects, the pump cavity can comprise one inlet and one outlet. In some aspects the pump cavity can comprise two inlets and two outlets. In some aspects, the pump cavity can comprise one to five inlets, one to five outlets, or any combination thereof. The size of the inlets and the outlets can be selected based on the size of the rollers, discussed in further detail below. Preferably, the inlet and the outlet each have a diameter that is smaller than a diameter of each of the rollers used in the roller pump apparatus. The inlets and outlets can generally be of any shape, including circular, elliptical, square, rectangular, irregular shape, or any combination thereof. “Diameter” as used herein to describe the inlet and outlet refers to the longest cross-sectional dimension of the inlet or outlet. In some aspects, the roller pump apparatus can comprise a plurality of outlets, for example two to five outlets. Each of the plurality of outlets can have a diameter that is less than the diameter of the inlets.

[0029] Positioning of the inlets relative to the outlets can affect the forces on the pump apparatus. In some aspects, it can be advantageous to balance the forces on the rotor by aligning the inlets and the outlets across opposing sides of the rotor.

[0030] In some aspects, the housing can comprise more than one pump cavity, for example, two, three, four, or more pump cavities. In some aspects, the inlet of a second pump cavity can be configured to receive a material from an outlet of a first pump cavity. When present, the inlet of a third pump cavity can be configured to receive a material from an outlet of the second pump cavity. A suitable number of pump cavities can be selected, for example, based on the material to be processed.

[0031] It will be understood that the diameter of each of the inlet and the outlet may vary based on, for example size of the apparatus, the material to be processed, and the number ofinlets and outlets. In some aspects, the inlets may have a diameter ranging from 2 to 20% of the rotor diameter. In some aspects, the outlets may have a diameter of 10 to 100% of the inlet diameter. Rotor diameters will vary by application and may vary, for example, from 1 to 10 millimeters for micro-dispensing applications (e.g., having processing flow rates on the order of microliters or less per second) to 10 to 50 centimeters for macro-dispensing applications (e.g., having processing flow rates on the order of liters or more per second) with many applications in between (e.g. polymer processing often having flow rates on the order of 0.01 to 500 cubic centimeters per second). The rotor, inlet, and outlet designs are readily implemented according to the described embodiments and related methods.

[0032] The roller pump apparatus further comprises a rotor mounted within the pump cavity. The rotor comprises a plurality of lobes. Each of the lobes extend away from the center of the rotor. The lobes can be equally spaced apart around the rotor. The lobes can define a convex outline and the base portion of each lobe can define a concave outline that together define the outer perimeter of the rotor. Exemplary lobed rotors are depicted in the figures. The rotor can comprise any suitable number of lobes, for example from 4 to 10 lobes, or 4 to 9 lobes. In some aspects, an odd number of lobes can be preferred. Without wishing to be bound by theory, an odd number of lobes can be preferred due to providing a more consistent flow due to staggered peak flows from the outlets of the apparatus.

[0033] The roller pump apparatus further comprises a plurality of rollers. The number of rollers is selected to be equal to the number of lobes of the rotor. Each roller is disposed between adjacent lobes of the rotor and free to rotate as well as move in the radial and angular directions. Upon rotor rotation, the faces of the rotor will contact and apply forces to the rollers. Each roller will tend to be driven outward until contact is also made with the outer wall of the pump cavity. Thus, entrapped volumes (such as the volume 101 near the inlet and the volume 102 near the outlet) are dynamically formed with varying volume as a function of the rotor angle. For example, volume 102 is defined by surfaces including the local rotor walls 103, forward face of the lagging roller 104, outer cavity wall 105, rearward face of the leading roller 106, front cavity wall 107, and rear cavity wall 101 such as shown in FIG. 1C. The difference between the volumes 101 and 102 determines the volumetric displacement per lobe per rotation of the rotor.

[0034] The rollers can be smooth or can be provided with surface features that may enhance mixing. For example, the cylindrical surface of each roller can independently be smooth, rough, grooved, diamond patterned, or the like such as shown by the surface 106 of the enclosed volume 102 in FIG. 1C. Suitable surface features can be selected by a skilled person guided by the present disclosure. Each of the plurality of rollers within a given pump cavity preferably have the same dimensions. When a plurality of pump cavities are present, thedimensions or surface features of the rollers may differ from one pump cavity to the next. In some aspects, each of the plurality of rollers within a given pump cavity have a length L and a diameter D, wherein a ratio of L:D is 0.5:1 to 1 :2, or 0.6:1 to 1 :1.5, or 0.7:1 to 1:1.2, or 0.8:1 to 1:1.1, or 0.9:1.1 to 1.1:0.9, or 0.95:1.05 to 1.05:0.95, or 0.99:1.01 to 1.01:0.99, or 1 :1.

[0035] The outer wall of the pump cavity, the plurality of lobes, and the plurality of rollers are configured to form a dynamically changing entrapped volume that varies with rotation of the rotor. The formation of the dynamically changing entrapped volume enables the roller pump apparatus of the present disclosure to process a feed material in the absence of a screw (e.g., as a screwless extruder). The rotation of the rotor drives the material from the inlet of the pump cavity to the outlet of the pump cavity.

[0036] In some aspects, the roller pump apparatus can optionally further comprise a feed screw. The feed screw, when present can be connected to rotor. The inlet of the pump cavity can be configured to receive a material input from the feed screw.

[0037] In another advantageous feature, the roller pump assembly of the present disclosure can be adapted to process a variety of materials, for example polymers, pharmaceuticals, foods, fluids, blends, and the like. Material flow rates, and operating temperature and pressure can be adjusted in order to process a particular material. In some aspects, the roller pump assembly can be operated at a temperature of -100 to 500 °C. In some aspects, the roller pump assembly can be operated at a pressure of 0 to 2000 bar. In some aspects, the flow rate of the material to be processed can be 0 to 10 kg / s, or greater than 0 to 10 kg / s.

[0038] Another aspect of the present disclosure is a method of processing a material. The method can comprise providing the roller pump apparatus described herein; supplying the material to an inlet of the roller pump apparatus; and driving the material from the inlet to an outlet of the roller pump apparatus by rotation of the rotor. In an aspect, the method can comprise providing a housing comprising a pump cavity and have a rotor comprising a plurality of lobes mounted in the pump cavity. A plurality of rotors can be disposed in the pump cavity, wherein each roller is located between adjacent lobes of the rotor, and there are an equal number of lobes and rollers. The method further comprises providing a material to an input of the pump cavity, and forming a dynamically changing entrapped volume between an outer wall of the pump cavity, the rotor lobes, and the rollers. The material is driven from the inlet to the outlet of the pump cavity by rotation of the rotor, thereby transporting and processing the material through the roller pump apparatus. As discussed above, the material to be processed can comprise polymers, pharmaceuticals, foods, fluids, and blends thereof.

[0039] In a specific aspect, the roller pump assembly of the present disclosure can beparticularly well suited to processing of polymeric materials. Accordingly, a method of polymer processing represents another aspects of the present disclosure.

[0040] A method of polymer processing comprises providing the roller pump apparatus of the present disclosure; supplying a polymer composition to an inlet of the roller pump apparatus; and driving the polymer composition from the inlet to an outlet of the roller pump apparatus by rotation of the rotor. In an aspect, the method can comprise providing a housing comprising a pump cavity and have a rotor comprising a plurality of lobes mounted in the pump cavity. A plurality of rotors can be disposed in the pump cavity, wherein each roller is located between adjacent lobes of the rotor, and there are an equal number of lobes and rollers. The method further comprises providing the polymer composition to an input of the pump cavity, and forming a dynamically changing entrapped volume between an outer wall of the pump cavity, the rotor lobes, and the rollers. The polymer composition is driven from the inlet to the outlet of the pump cavity by rotation of the rotor, thereby transporting and processing the polymer composition through the roller pump apparatus.

[0041] Suitable polymer compositions to be processed can generally comprise one or more thermoplastic polymers, and optionally one or more additives.

[0042] As used herein, the term "thermoplastic" refers to a material that is plastic or deformable, melts to a liquid when heated, and freezes to a brittle, glassy state when cooled sufficiently. Thermoplastics are typically high molecular weight polymers. Examples of thermoplastic polymers that can be used include polyacetals (e.g., polyoxyethylene and polyoxymethylene), poly(Ci-6 alkyl)acrylates, polyacrylamides, polyamides, (e.g., aliphatic polyamides, polyphthalamides, and polyaramides), polyamideimides, polyanhydrides, polyarylates, polyarylene ethers (e.g., polyphenylene ethers), polyarylene sulfides (e.g., polyphenylene sulfides), polyarylsulfones, polybenzothiazoles, polybenzoxazoles, polycarbonates (including polycarbonate copolymers such as polycarbonate-siloxanes, polycarbonate-esters, and polycarbonate-ester-siloxanes), polyesters (e.g., polyethylene terephthalates, polybutylene terephthalates, polyarylates, and polyester copolymers such as polyester-ethers), polyetheretherketones, polyetherimides (including copolymers such as polyetherimide-siloxane copolymers), polyetherketoneketones, polyetherketones, polyethersulfones, polyimides (including copolymers such as polyimide-siloxane copolymers), poly(Ci-6 alkyl)methacrylates, polymethacrylamides, polynorbomenes (including copolymers containing norbomenyl units) polyolefins (e.g., polyethylenes, polypropylenes, polytetrafluoroethylenes, and their copolymers, for example ethylene-alpha-olefin copolymers), polyoxadiazoles, polyoxymethylene, polyphthalides, polysilazanes, polysiloxanes, polystyrenes (including copolymers such as acrylonitrile-butadiene-styrene (ABS) and methyl methacrylate-butadiene-styrene (MBS)), polysulfides, polysulfonamides, polysulfonates, polysulfones, polythioesters, polytriazines, polyureas, polyurethanes, polyvinyl alcohols, polyvinyl esters, polyvinyl ethers, polyvinyl halides, polyvinyl ketones, polyvinyl thioethers, polyvinylidene fluorides, or the like, or a combination comprising at least one of the foregoing thermoplastic polymers. Polyacetals, polyamides (nylons), polycarbonates, polyesters, polyetherimide, polyolefins, and polystyrene copolymers such as ABS, are especially useful in a wide variety of articles, have good processability, and are recyclable.

[0043] Useful polyamides include, but are not limited to, synthetic linear polyamides, e.g., Nylon-6, 6; Nylon-6, 9; Nylon-6, 10; Nylon-6, 12; Nylon-11; Nylon-12 and Nylon-4, 6, preferably Nylon 6 and Nylon 6,6, or a combination comprising at least one of the foregoing. Polyurethanes that can be used include aliphatic, cycloaliphatic, aromatic, and polycyclic polyurethanes, including those described above. Also useful are polyacrylates and polymethacrylates, which include, for example, polymers of acrylic acid, methyl acrylate, ethyl acrylate, acrylamide, methacrylic acid, methyl methacrylate, n-butyl acrylate, and ethyl acrylate, to name a few.

[0044] Representative examples of polyolefins, as thermoplastic polymers are polyethylene, polypropylene, polybutylene, polymethylpentene (and co-polymers thereof), polynorbomene (and co-polymers thereof), poly 1 -butene, poly(3 -methylbutene), poly(4- methylpentene) and copolymers of ethylene with propylene, 1 -butene, 1 -hexene, 1 -octene, 1- decene, 4-methyl-l -pentene and 1 -octadecene. Representative combinations of polyolefins are combinations containing polyethylene and polypropylene, low-density polyethylene and high- density polyethylene, and polyethylene and olefin copolymers containing copolymerizable monomers, some of which are described above, e.g., ethylene and acrylic acid copolymers; ethyl and methyl acrylate copolymers; ethylene and ethyl acrylate copolymers; ethylene and vinyl acetate copolymers-, ethylene, acrylic acid, and ethyl acrylate copolymers, and ethylene, acrylic acid, and vinyl acetate copolymers.

[0045] An additive composition can be used, comprising one or more additives selected to achieve a desired property, with the proviso that the additive(s) are also selected so as to not significantly adversely affect a desired property of the thermoplastic composition. The additive composition or individual additives can be mixed at a suitable time during the mixing of the components for forming the composition. The additive composition can include an impact modifier, flow modifier, filler (e.g., a particulate polytetrafluoroethylene (PTFE), glass, carbon, mineral, or metal), reinforcing agent (e.g., glass fibers), antioxidant, heat stabilizer, light stabilizer, ultraviolet (UV) light stabilizer, UV absorbing additive, plasticizer, lubricant, release agent (such as a mold release agent), antistatic agent, anti-fog agent, antimicrobial agent,colorant (e.g., a dye or pigment), surface effect additive, radiation stabilizer, flame retardant, anti-drip agent (e.g., a PTFE-encapsulated styrene-acrylonitrile copolymer (TSAN)), or a combination thereof. For example, a combination of a heat stabilizer, mold release agent, and ultraviolet light stabilizer can be used. In general, the additives are used in the amounts generally known to be effective. For example, the total amount of the additive composition (other than any impact modifier, filler, or reinforcing agent) can be 0.001 to 10.0 wt%, or 0.01 to 5 wt%, each based on the total weight of the polymer in the composition.

[0046] Advantageously, the rotational speed of the rotor and the flow rate of the polymer composition can be adjusted to suit specific requirements of a given manufacturing process, for example extrusion, 3D printing, injection molding, thermoforming, blow molding, or rotomolding. In some aspects, the output of the roller pump apparatus can be configured to supply the polymer composition directly to a die, nozzle, mold cavity, or other forming tool associated with the selected process. In some aspects, the temperature and pressure within the pump cavity can be selected to provide a desired set of properties of the polymer composition that may be necessary for the selected manufacturing process. The material processed according to the methods described herein can be used in the selected manufacturing process to provide an article comprising the polymer composition.

[0047] According to an aspect of the present disclosure, a roller pump apparatus creates a set of dynamically formed entrapped volumes in which each entrapped volume is defined by the boundaries of the rotor, adjacent rollers, and outer wall of a pump cavity (e.g., an eccentric circular pump cavity). An exemplary apparatus is illustrated in FIG. 1. As shown in FIG. 1, the apparatus also includes one inlet from which material is driven by the rotor rotation and change in material volume to an outlet, or optionally to a series of smaller outlets, that are generally located opposite the inlet. This optional outlet design ensures that processed material that is larger than the outlet ports is reprocessed via recirculation within the pump. This reprocessing allows partially processed material to circulate and undergo additional refinement before progressing, with barrier channels, filters, and other mechanisms in place to ensure adequate processing at each stage.

[0048] Also as shown in FIG. 1 , the rotor is near its position of maximum inlet volume and minimum outlet volume, whereby the difference in the two entrapped volumes represents the volumetric displacement of the pump per lobe per rotation. As such, the volumetric output of the pump per minute can be estimated as the product of this volumetric displacement, number of lobes, and operating speed of the pump as measured in revolutions per minute (RPM).

[0049] Without wishing to be bound by theory, the volumetric displacement is primarily driven by several pump design parameters including the diameter and depth of the pump cavity,eccentricity of the rotor to the pump cavity, number of rollers, and diameter of the rollers. Other factors, such as the included angle of the rotor arms, outer diameter of the rotor arms, and detailed features (fillets, grooves, etc.) disposed on the rotor and rollers are of lesser significance. While design parameters will vary by application and preference, in an exemplary aspect, each of the four rollers can measure 11.7 mm in diameter and 17.6 mm in length, operating within a circular cavity having a diameter of 50 mm located 1.5 mm eccentric to the rotor’s rotational axis; the center of the cavity can be disposed at an angle of 30 degrees relative to the vertical plane to accommodate material being fed from a feedthroat located above (not shown in FIG. 1). The cavity depth at this stage can be 18 mm, allowing an axial clearance of 0.2 mm on each end of the rollers.

[0050] The outlet of the pump of FIG.1 can be directed to the inlet of a second pump stage such as shown in FIG. 2A-2C. This subsequent stage features a rotor with eight rollers (FIG. 2C) situated in an eccentric cavity having a smaller diameter than the cavity of the first stage (i.e., of FIG. 2A), causing an increase in volumetric compression from the first stage to the second stage. Such a design ensures that each stage uses smaller entrapped volumes compared to the previous, enhancing the material's density (specific gravity, SG) and elevating its pressure by the time it reaches the final outlet.

[0051] The design of FIG. 2A also exhibits optional design features such as a feed throat integral with the housing above the first pump stage, a heater on the outside of the pump housing surrounding the second stage, and other design details such as a keyed shaft, thrust bearings, radial bearings, mounting plates, shaft coupling, and brushless DC motor with a gearbox having 20:1 reduction. The rollers of the design of FIG. 2B and 2C not only have varying diameter and length, but also grooves and other features on their cylindrical faces to improve distributive and dispersive mixing of the material being processed. While depicted in FIG. 2, such features on the surface of the rollers are not required.

[0052] The design and operation of the roller pump are like that of vane pumps and roller vane pumps in that all these designs use a dynamic seal between the volumes of the processed material with rotor rotation. In vane pumps, blade-shaped vanes are disposed within the cavities of the rotor lobe and often spring biased to form the dynamic seal with the main cavity of the pump. Roller vane pumps are like vane pumps, but with each vane replaced by a spring loaded roller located within a cavity having two parallel walls within each rotor lobe. The present roller pump apparatus operates quite differently in that the rotor lobes are not spring loaded but located in the dynamically formed enclosed volume. Rather, the dynamically formed enclosed volume of the claimed roller pump beneficially employs an obtuse included angle defined by the adjacent side walls of the rotor lobes. This design has two advantages over previous roller vane pumps.First, the large internal volume defined within the included angle provides for residence, circulation, and reprocessing of the material being processed to increase the working time. Second, the obtuse included angle provides higher outward contact forces between the rotor, rollers, and outer wall of the cavity to ensure sealing and pumping at high operating pressures.

[0053] The contact forces can be engineered by analysis of the force triangles at various rotor and roller positions, and are useful to confirm the location of the rollers as well as the contact stresses between the rotor, roller, and cavity wall. The contact forces are estimated through the static analysis of the appropriate force triangles with the measurements as indicated. The normal force, F, at the roller imposed by rotor is estimated as T / R where T is the torque estimate per rotor lobe and R is the radius from the rotor centerline to the roller contact location. Table 1 provides the dimensions and force estimates assuming an equal distribution of the torque across the two pump stages and rollers in each stage as depicted in the two stage roller pump of FIG. 2A-2C. It is observed that the outward force applied to the outer wall by the roller is a significant fraction of the normal force applied to the roller by the rotor wall. Indeed, the outward force exerted by the roller (at the roller:cavity interface) will exceed the lateral force (at the roller:rotor) interface when the angle of the drive point, AD, is greater than 135 degrees.Generally, drive angles between 120 and 150 degrees can be preferred.Table 1

[0054] The contact stress, o, at the cylinder:wall interface is estimated by Hertzian contact analysis according to the equation: a = 0.418FE(-R2 R1)-d 2LR2R-

[0055] Here, E is the modulus of the machine elements (steel), Ri and R2 are the respective radii of the roller and bore, F is the outward force at the cylinder:wall interface, and L is the length of the rollers. The applied torque at the roller is assessed as the maximum output torque (20 Nm) of a geared brushless DC motor applied equally as 10 Nm to each stage and subsequently divided to each roller. The results of Table 1 indicate that the contact stress is well within the limits of steel and bearing bronze from which the components are made. The size of the rollers, design of the cavity and rotors, and the resulting drive point, AD, can be selected based on the operating requirements of each stage. Generally, this contact stress should exceed the operating pressure of the pump. This level of contact stress is readily achieved with angles of AD greater than 90 degrees but preferably greater than 100 degrees and even more preferably in the vicinity of 135 degrees.

[0056] The displacement, D, for each stage is driven by the difference in inlet and outlet volumes such as that shown in FIG. 3 as:

[0057] Here, n is the number of rollers, £ is the output fraction per roller estimated as R / l, Viniet and Voutiet are the respective inlet and outlet volumes. The outlet flow, Q, from each stage is then estimated as EFAt given At as the time per rotor rotation (equal to 60 s / RPM). The stage compression ratio is calculated as Voutie Viniet. Given the total material volume, M, in each stage, the throughput ratio is estimated as D / M and the reprocessing ratio as l-(EFM). The mean residence time in each stage can then be calculated as At / ((1-(D / M))).

[0058] The power required to process the material is estimated as the sum of the required melting and pumping power. The melting power is estimated as:

[0059] Here, m’ is the mass flow rate, Cp is the specific heat of the melt, and TMeit and TRoom are the respective melt and room temperatures. The pumping power is estimated as the product of the outlet flow, Q, and the peak die pressure, P.

[0060] The results of the flow and power analysis for the implemented design of FIG. 2 are listed in Table 2. The results indicate that the design is constrained by the output of the second stage, which is equal to 0.3 kg / hr. This low output from the second stage was chosen on purpose to ensure that the design provided sufficient residence time for heating the processed material in this application while the system remains within the available power constraints . Table 2

[0061] In the design of FIG. 2, a 250 Watt heater band was fitted to the outside of the die and second stage rotor housing; in another build, four heater cartridges were provided inside bores located at the four comers of a housing providing the pump cavities. A cooling plate having fins and fans was used to cool the feed throat and inlet of the first stage. Other heating, cooling, and temperature control methods can be readily implemented.

[0062] A closed loop temperature controller was wired using solid state relay controlled by pulse width modulation from an Arduino R4 Wifi based on the feedback temperature at the die:heater interface. A brushless DC motor #57BLR90-24-01-HG50 (Stepper Online, Nanjing City, China) with a 50:1 planetary gear reduction was driven with driver #BLD-510S that was likewise controlled via a pulse width modulation signal from the Arduino. A compact melt pressure transducer PT462E-M10 (Dynisco, Franklin, MA) was installed in the outlet port of the second stage just prior to the die land. Polypropylene (PP, PROFAX 6523, Geon Performance Solutions, Avon Lake, OH) was used for the experiments.

[0063] In operation, the output from the die was observed to have a peristaltic behavior with a pulsed flow of the extrudate corresponding to the traversal of each roller past the second stage outlet port. The modeled and observed flow rate closely follow each other, largely due to the pumping efficiency, £, which was estimated as D / (D+L) corresponding to just 30% for the second stage roller. This low pumping efficiency occurs for two reasons. First, the roller is relatively long such that it isn’t possible for the melt received on one end of the roller at the inlet of the second stage to traverse the length of the roller during just half a rotor turn. Second, the channels provided on the cylindrical roller allow a significant amount of back flow given the leakage at the roller:cavity interface. Accordingly, the volumetric output is greatly increased byusing straight cylindrical rollers with a larger diameter and shorter length to increase the pumping efficiency, E.

[0064] Both the first and second pumping stages in FIG. 2A-2C are unbalanced in that there is a significant lateral net force being applied to the drive shaft via the faces of the rotor with lower pressures near the inlet and higher pressures near the outlet. At high loadings, the lateral forces are significant enough to cause deflection, as evidenced by noise (squealing) and wear.

[0065] A significant advantage of the roller pump design is that it may be implemented with a balanced rotor design in which two sets of inlets and outlets are provided such that approximately equal lateral loadings are applied to opposing sides of the shaft. The pump may then be operated at high speeds, throughputs, and loadings without excessive stresses or deflections.

[0066] FIG. 3 provides a balanced four lobe roller pump design. In this design, the pump cavity 301 has an elliptical shape with a major diameter A and a minor diameter B with a centerline located colinearly with the rotor centerline. The inlets 302 and outlets 303 are disposed in opposing plates. The difference between the ellipsoidal cavity’s major and minor diameters drives a difference in the associated inlet and outlet volumes to perform a pumping function. In operation, the resulting forces on the rotor are balanced so as to reduce radial loads on the rotor and bearings. However, the balanced design of FIG. 3 will still result in a peristaltic or pulsating output flow given the concurrent intake and outflow from the opposing sides of the elliptical cavity.

[0067] FIG. 4 provides a set of balanced roller pump designs with a varying number of rollers with four rollers in section 404, five rollers in section 405, six rollers in section 406, seven rollers in section 407, eight rollers in section 408, and nine rollers in section 409. Each of the designs has the same pump cavity with a major diameter, A, and a minor diameter, B. To accommodate an increased number of rollers in the same sized ellipsoidal cavity, the diameter of the rollers is reduced as the number of rollers is increased as shown in Table 3. To ensure sufficient pumping efficiency from the inlet to the outlet (across the depth of the cavity), the length of the rollers is set equal to the diameter of the rollers.

[0068] The estimated volumetric displacements are shown in FIG. 5 for the designs of FIG. 4 with trace 504 for four rollers, trace 505 for five rollers, trace 506 for six rollers, trace 507 for seven rollers, trace 508 for eight rollers, and trace 509 for nine rollers. These results were calculated in Matlab using the previously described formula including computation of the entrapped volumes as a function of the rotor rotation angle and associated volumetric displacement. A quantitative summary is also provided in the three right-most columns of Table3. In Table 3, the coefficient of variation is a fraction defined as the standard deviation of the volumetric flow rate divided by the mean volumetric flow rate.

[0069] Analysis from FIG. 5 and Table 3 yields three insights. First, while feasible, using four or fewer rollers leads to significant fluctuations in volumetric output due to the limited duration of cavity formation during rotor rotation. Second, pumps with an odd number of lobes produce a steadier output than those with an even number because the flow peaks are staggered; as one outlet reaches maximum flow, the opposing outlet's flow is minimal, enhancing overall flow uniformity. Although the forces on the rotor are not fully balanced with an odd number of rollers, they are considerably lower than those in the unbalanced designs of FIG. 1 and FIG. 2.Table 3

[0070] A third key insight from FIG. 5 and Table 3 is that increasing the number of rollers decreases both the volumetric output and the coefficient of variation. This reduction occurs because as more rollers are added to fit within the ellipsoidal cavity, both their diameter and the pump cavity’s depth decrease, leading to smaller volumetric displacement per rotor lobe. Despite this reduction in output, the consistency improves as quantified by the lower coefficient of variation. By using this analysis, optimal roller count, dimensions, and cavity size can be precisely configured to balance desired output levels with targeted levels of consistency.

[0071] A practical consideration is the manufacture and assembly of pump designs having multiple stages. While the use of two pumping stages is readily implemented in a single housing such as shown in FIG. 2A-2C, the design, manufacture, and assembly of pumps with three or more stages with a single driven rotor is less obvious. Such designs have been implemented by a series of plates in which intermediate plates were provided containing the inlet ports, outlet ports, and collector as previously described. All the plates were provided tightly tolerance bores at their four corners for mating and closing with shoulder bolts. The resulting assembly was found to function well with low friction. There are two minor issues with that design, however. First, the manufacture and assembly of multiple plates is a hassle with respect to tracking the components, orienting the parts during assembly, etc. Second, the inclusion of the bores for the shoulder bolts requires a larger size in the housing than would be necessary for an integral design such as shown in FIG. 2.

[0072] These challenges can be addressed by designing an integral housing for the cavities of multiple pump stages such as shown in FIG. 6A. As shown in FIG. 6A, the roller pump assembly comprises a housing 604 that comprises a plurality of pump cavities, each having a lobed rotor 603 disposed therein. Rotor seal plates 605 are positioned between each pump cavity. The apparatus includes a clamp plate 602, inlet ports 601, and outlet ports 606.

[0073] This design takes advantage of the fact that each of the cavities in successive pump stages tends to be smaller than the cavity in the preceding stage. The optional transition rotor may have an outer diameter equal to the major diameter of the preceding stage for which the design of FIG. 6A also operates. While successive cavities are typically rotated 90 degrees with respect to the prior cavity, there is sufficient allowance between the major and minor diameters to allow overlapping seals between provided rotor sealing plates and subsequent cavities. The outlets from each plate are disposed near the convergence of the rotor with the minor diameter of the elliptical pump cavity. As shown in FIG. 6A, the outlets from each upstream cavity are directly connected to the inlets of the downstream cavity. The radial dimension of the outlet may be varied with each stage to act as a filter and ensure that the size of any solids in the processed material are less than this radial dimension and appropriate for downstream processing.

[0074] The multi-staged rotor design of FIG. 6A may be provided as a single integral component, shown as FIG. 6C. It may at times be preferable to manufacture and assemble the rotor as a series of plates such as two opposing keyways as shown for the rotors in FIG. 2. The sealing plates on the rotor may likewise be machined plates, or each stage’s sealing plate and rotor plate may be machined together as an integral piece. FIG. 6C, for example, provides a stacked rotor assembly on a DD shaft (a shaft with flats on opposite sides). Rotor plates (and sealing plates if not integral with the rotors) may be assembled onto the shaft and the rotor assembly placed into the housing of FIG. 6A as a cassette.

[0075] The end of the shaft in FIG. 6C has a circular section that mates with a circular cavity in the housing to provide a radial bearing. The housing at this location may otherwise be fitted with a radial, tapered roller, or other bearing. An optional leakage port may be added to connect any material at the distal end of the rotor to connect to the outlet of the housing, thereby avoiding stagnation and degradation of any material leaking through the radial bearing. The integral housing may be provided a collector connecting the two outlets of the last pump stage to the outlet of the die; the final die orifice is located in an attached plate (not shown). This plate may also include die details known in the art for shaping a profiled extrusion, a tapped bore for receiving interchangeable nozzles with varying orifice shapes and sizes, or otherwise connect to other downstream processing equipment such as conveyance pipes, feedblocks, and othersystems for processing one or more materials.

[0076] The roller pump design may also be attached to a feed screw that supplies material to the pump inlet(s), as illustrated in FIG. 7. In this design, the feed screw is attached to the roller pump apparatus. Three heaters were disposed along its length including a 150 W heater in the feed section, a 300 W heater in the transition section, and a 200 W heater in the metering and pumping section. The feed screw had two flights with intermittent mixing sections prior to the pumping section.

[0077] A design of an integral roller pump is shown in FIG. 8. The roller pump was a balanced design (two inlets and two outlets) with five rollers having an approximately equal length and diameter. The pump cavity was an ellipsoidal shape with a major diameter longer than a minor diameter.

[0078] The validation results for the designs of FIG. 2 and FIG. 7 are provided in FIG. 9 using polypropylene as the material to be processed. The volumetric output was found to be nearly linear with the rotor speed. The design of FIG. 7 was found to provide much higher volumetric output and operable to much higher rotor speeds than the design of FIG. 2. Without wishing to be bound by theory, the reasons for the improved performance of FIG. 7 are believed to be that the supply of the infed material via the feed screw was greatly improved compared to the gravity-driven infeed from the feed throat of FIG. 2. The balanced design of the roller pump in FIG. 7 also allowed for higher operating speeds than the unbalanced design of FIG. 2.

[0079] In FIG. 7, the roller pump is integrally machined into the feed screw and sized so that the outer radius of the roller lobes is generally co-radial with the diameter of the feed screw. While this design is simple, a modular design (pump separable from the feed screw) with a keyed shaft or other connecting means can provide greater flexibility. Such a modular design allows the pump design to be readily adjusted independent of the feed screw. This configuration also allows for integration of porting plates, filters, breaker plates, seals, piping, heaters, instrumentation, and other components in a modular assembly that can be readily disassembled and maintained at the component level.

[0080] The pump can operate independent of the feed screw, such that the pump may be provided its own drive motor and operated at a different speed from the feed screw. Such a design allows fine adjustment of the relative output flow rates and compression ratio to provide fine tuning of the control. The pump may be operated with its drive axis oriented parallel, perpendicular, or in other directions relative to the direction of gravity. If operated with the drive axis parallel to gravity, then the rollers will tend to be forced outwards to contact the cavity wall given the obtuse included angle of the cavity in which the roller resides between adjacent rotor lobes. When operated with the drive axis perpendicular to gravity, the rollers can be pulled awayfrom the cavity wall when the rollers are above the horizontal plane of the drive axis and the operating pressures are low. In practical use, however, operation with the drive axis perpendicular to gravity was found acceptable due to the combined effect of frictional (contact), centrifugal, and gravitational forces.

[0081] The design of FIG. 7 may be directly used as an extruder to manufacture filament through the nozzle orifice 701. Extrusion dies and related auxiliary equipment may also be fitted to the extruder for production of pipe, tubing, catheters, and other profiled products as common. The design of FIG. 7 may also be mounted to a 3D printing with appropriate moving stages to deposit roads to form complex 3D structures. In such processes, the rotational speed of the feed screw and pump are adjusted to provide positive displacement control of the output volumetric flow rate in proportion to the desired deposition flow rate defined as the product of the print velocity, road height, and road width.

[0082] The design of FIG. 7 may also be integrated into other molding processes such as injection molding and rotomolding whereby the processed material is intermittently injected into one or more mold cavities. Such application eliminates the need for reciprocating screws, resulting in not only more compact and less expensive machinery but also reduced cycle times and improved operating efficiencies. In these applications, the volumetric flow rate and the integral of the volumetric flow rate may be controlled via the roller pump’s rotational speed and total rotational travel. The operating pressure at the inlet to the mold or elsewhere in the mold may also be fed back to the pump controller to incrementally dose material into the cavity to provide dynamic control of the pressure as a function of time. The pump rotational speed and travel during the injection and pressure control phases can be used for quality assurance.

[0083] The design illustrated in FIG. 7 can also be adapted for use in other molding processes such as blow molding and thermoforming. For blow molding, the pump's output can be connected directly to a die head to produce a parison. The rotor's operation can be adjusted intermittently and at variable speeds to program parison thickness and synchronize the start and stop of parison extrusion with the opening and closing of the blow mold. In thermoforming processes, the pump’s output may be directed to a film or sheet die to generate planar feedstock. Here, the rotor’s speed can be varied or controlled intermittently, in concert with downstream processes, to manage the gauge thickness of the sheet and enhance the quality of the final thermoformed product.

[0084] The foregoing embodiments were provided for demonstrative purposes only and were not intended to limit the methods of design, designs, or methods of use in any way. While the provided embodiments are described without mention of materials, they were designed to operate for polymer, food, and other materials wherein the feedstock may contain a variety ofsolids and liquids, including mixtures thereof, and at a variety of temperature, pressures, and flow rates. While the foregoing embodiments were designed and validated for pilot production and 3D printing, smaller and larger variations are readily obtained with ordinary practices. Many diverse designs and processes are thus enabled by the present disclosure.

[0085] This disclosure further encompasses the following aspects.

[0086] Aspect 1: A roller pump apparatus comprising: a housing comprising a pump cavity defined by an outer wall and having an inlet and an outlet; a rotor mounted within the pump cavity, wherein the rotor comprises a plurality of lobes; a plurality of rollers, wherein each roller is disposed between adjacent lobes of the rotor, and wherein the number of rollers is equal to the number of lobes; wherein the outer wall of the pump cavity, the plurality of lobes, and the plurality of rollers are configured to form a dynamically changing entrapped volume that varies with rotation of the rotor; wherein rotation of the rotor drives material from the inlet to the outlet of the pump cavity.

[0087] Aspect 2: The roller pump apparatus of aspect 1, wherein the pump cavity is an eccentric pump cavity having one inlet and one outlet.

[0088] Aspect 3: The roller pump apparatus of aspect 1, wherein the pump cavity is a co-axial elliptical pump cavity having two inlets and two outlets.

[0089] Aspect 4: The roller pump apparatus of aspect 1, wherein the outlet comprises a plurality of outlets, wherein each of the plurality of outlets has a diameter that is less than a diameter of the inlet.

[0090] Aspect 5: The roller pump apparatus of any of aspects 1 to 4, wherein the inlet and the outlet have a diameter smaller than a diameter of each of the plurality of rollers.

[0091] Aspect 6: The roller pump apparatus of any of aspects 1 to 5, wherein the rotor comprises an odd number of rotor lobes.

[0092] Aspect 7: The roller pump apparatus of any of aspects 1 or 3 to 6, wherein the pump cavity comprises two inlets and two outlets, wherein the inlets and the outlets are aligned across opposing sides of the rotor.

[0093] Aspect 8: The roller pump apparatus of any of aspects 1 to 7, wherein the roller pump apparatus further comprises a feed screw.

[0094] Aspect 9: The roller pump apparatus of any of aspects 1 to 8, wherein a cylindrical face of each of the plurality of rollers comprises a plurality of surface features.

[0095] Aspect 10: The roller pump apparatus of any of aspects 1 to 9, wherein the inlet to the pump cavity is configured to receive a material output from an outlet of a different pump cavity.

[0096] Aspect 11 : The roller pump apparatus of any of aspects 1 to 10, wherein thehousing comprises two or more pump cavities.

[0097] Aspect 12: The roller pump apparatus of any of aspects 1 to 11, wherein the inlet to the pump cavity is configured to receive a material output from a feed screw.

[0098] Aspect 13: The roller pump apparatus of aspect 12, wherein the rotor is connected to the feed screw.

[0099] Aspect 14: The roller pump apparatus of any of aspects 1 to 13, wherein each of the plurality of rollers has a length L and a diameter D, wherein a ratio of L:D is 0.5 : 1 to 1 :2.

[0100] Aspect 15: The roller pump apparatus of any of aspects 1 to 14, wherein the apparatus is configured to process polymers, pharmaceuticals, foods, fluids, and blends thereof.

[0101] Aspect 16: A method of processing a material, the method comprising: providing the roller pump apparatus of any of aspects 1 to 15; supplying the material to an inlet of the roller pump apparatus; and driving the material from the inlet to an outlet of the roller pump apparatus by rotation of the rotor.

[0102] Aspect 17: The method of aspect 16, wherein the pump cavity is an eccentric pump cavity having one inlet and one outlet.

[0103] Aspect 18: The method of aspect 16, wherein the pump cavity is a co-axial elliptical pump cavity having two inlets and two outlets.

[0104] Aspect 19: The method of any of aspects 16 to 18, wherein the rotor comprises an odd number of rotor lobes.

[0105] Aspect 20: The method of any of aspects 16 or 18 and 19, wherein the pump cavity comprises two inlets and two outlets, wherein the inlets and the outlets are aligned across opposing sides of the rotor.

[0106] Aspect 21: The method of any of aspects 16 to 20, further comprising integrating a feed screw with the roller pump to supply the material to the inlet of the roller pump apparatus.

[0107] Aspect 22: The method of aspect 21, further comprising operating the feed screw at the same rotational speed as the rotor of the roller pump assembly.

[0108] Aspect 23: The method of aspect 21, further comprising operating the feed screw at a different rotational speed as the rotor of the roller pump assembly.

[0109] Aspect 24: The method of any of aspects 16 to 23, wherein the roller pump apparatus comprises two or more pump cavities.

[0110] Aspect 25: The method of aspect 24, wherein the two or more pump cavities are provided within a single housing, and the material flows sequentially through the pump cavities.

[0111] Aspect 26: The method of any of aspects 16 to 25, wherein a cylindrical face of each of the plurality of rollers comprises a plurality of surface features.

[0112] Aspect 27: The method of any of aspects 16 to 26, wherein the materialcomprises polymers, pharmaceuticals, foods, fluids, and blends thereof.

[0113] Aspect 28: A method for polymer processing, the method comprising: providing the roller pump apparatus of any of aspects 1 to 15; supplying a polymer composition to an inlet of the roller pump apparatus; and driving the polymer composition from the inlet to an outlet of the roller pump apparatus by rotation of the rotor.

[0114] Aspect 29: The method of aspect 28, wherein a rotational speed of the rotor is dynamically varied in coordination with other processing steps.

[0115] Aspect 30: The method of aspect 28 or 29, wherein a rotational speed of the rotor is dynamically varied in response to feedback from one or more process sensors.

[0116] Aspect 31: The method of any of aspects 28 to 30, wherein quality of the product is evaluated by monitoring rotational speed or total rotational displacement of the rotor.

[0117] The foregoing embodiments were provided for demonstrative purposes only and were not intended to limit the methods of design, designs, or methods of use in any way. While the provided embodiments are described without mention of materials, they were designed to operate for polymer, food, and other materials wherein the feedstock may contain a variety of solids and liquids, including mixtures thereof, and at a variety of temperature, pressures, and flow rates. While the foregoing embodiments were designed and produced for proof of concept and desktop manufacturing, smaller and larger variations are readily obtained with ordinary practices. Indeed, it is a significant advantage of the invention that multiple stages with varied sizes may be used to scale the apparatus to very high flow rates whereby the use of smaller rollers in the latter stages enables replication of the material processing in lab and pilot lines. Many diverse designs and processes are thus enabled by the invention as subsequently claimed.

[0118] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0119] While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

Claims

CLAIMS1. A roller pump apparatus comprising: a housing comprising a pump cavity defined by an outer wall and having an inlet and an outlet; a rotor mounted within the pump cavity, wherein the rotor comprises a plurality of lobes; a plurality of rollers, wherein each roller is disposed between adjacent lobes of the rotor, and wherein the number of rollers is equal to the number of lobes; wherein the outer wall of the pump cavity, the plurality of lobes, and the plurality of rollers are configured to form a dynamically changing entrapped volume that varies with rotation of the rotor; wherein rotation of the rotor drives material from the inlet to the outlet of the pump cavity.

2. The roller pump apparatus of claim 1, wherein the pump cavity is an eccentric pump cavity having one inlet and one outlet.

3. The roller pump apparatus of claim 1, wherein the pump cavity is a co-axial elliptical pump cavity having two inlets and two outlets.

4. The roller pump apparatus of claim 1, wherein the outlet comprises a plurality of outlets, wherein each of the plurality of outlets has a diameter that is less than a diameter of the inlet.

5. The roller pump apparatus of claim 1, wherein the inlet and the outlet have a diameter smaller than diameter of each of the plurality of rollers.

6. The roller pump apparatus of claim 1, wherein the rotor comprises an odd number of rotor lobes.

7. The roller pump apparatus of claim 1, wherein the pump cavity comprises two inlets and two outlets, wherein the inlets and the outlets are aligned across opposing sides of the rotor.

8. The roller pump apparatus of claim 1, wherein the roller pump apparatus further comprises a feed screw, wherein the rotor is connected to the feed screw, and wherein the inlet to the pump cavity is configured to receive a material output from a feed screw.

9. The roller pump apparatus of claim 1, wherein a cylindrical face of each of the plurality of rollers comprises a plurality of surface features.

10. The roller pump apparatus of claim 1, wherein the housing comprises two or more pump cavities, and wherein the inlet to a second pump cavity is configured to receive a material output from an outlet of a first pump cavity.

11. The roller pump apparatus of claim 1 , wherein each of the plurality of rollers has a length L and a diameter D, wherein a ratio of L:D is 0.5:1 to 1 :2.

12. A method of processing a material, the method comprising: providing a roller pump apparatus; supplying the material to an inlet of the roller pump apparatus; and driving the material from the inlet to an outlet of the roller pump apparatus by rotation of the rotor; wherein the roller pump apparatus comprises: a housing comprising a pump cavity defined by an outer wall and having an inlet and an outlet; a rotor mounted within the pump cavity, wherein the rotor comprises a plurality of lobes; a plurality of rollers, wherein each roller is disposed between adjacent lobes of the rotor, and wherein the number of rollers is equal to the number of lobes; wherein the outer wall of the pump cavity, the plurality of lobes, and the plurality of rollers are configured to form a dynamically changing entrapped volume that varies with rotation of the rotor; wherein rotation of the rotor drives material from the inlet to the outlet of the pump cavity.

13. The method of claim 12, wherein the pump cavity is an eccentric pump cavity having one inlet and one outlet; or the pump cavity is a co-axial elliptical pump cavity having two inlets and two outlets.

14. The method of claim 12, wherein the rotor comprises an odd number of rotor lobes.

15. The method of claim 12, wherein the pump cavity comprises two inlets and two outlets, wherein the inlets and the outlets are aligned across opposing sides of the rotor.

16. The method of claim 12, further comprising integrating a feed screw with the roller pump to supply the material to the inlet of the roller pump apparatus, wherein the feed screw is operated at a rotational speed that is the same or different as the rotational speed of the rotor of the roller pump assembly.

17. The method of claim 12, wherein the roller pump apparatus comprises two or more pump cavities are provided within a single housing, and the material flows sequentially through the pump cavities.

18. The method of claim 12, wherein a cylindrical face of each of the plurality of rollers comprises a plurality of surface features.

19. The method of claim 12, wherein the material comprises polymers, pharmaceuticals, foods, fluids, and blends thereof.

20. A method for polymer processing, the method comprising: providing a roller pump apparatus; supplying a polymer composition to an inlet of the roller pump apparatus; and driving the polymer composition from the inlet to an outlet of the roller pump apparatus by rotation of the rotor; wherein the roller pump apparatus comprises: a housing comprising a pump cavity defined by an outer wall and having an inlet and an outlet; a rotor mounted within the pump cavity, wherein the rotor comprises a plurality of lobes; a plurality of rollers, wherein each roller is disposed between adjacent lobes of the rotor, and wherein the number of rollers is equal to the number of lobes;wherein the outer wall of the pump cavity, the plurality of lobes, and the plurality of rollers are configured to form a dynamically changing entrapped volume that varies with rotation of the rotor; wherein rotation of the rotor drives material from the inlet to the outlet of the pump cavity.

Images