WO2023178278A2

WO2023178278A2 - Molded fiber part production lines using trimless forming and pressing molds

Info

Publication number: WO2023178278A2
Application number: PCT/US2023/064583
Authority: WO
Inventors: Thomas D. RIDDERBUSH; Michael John ASBEE
Original assignee: Zume, Inc.
Priority date: 2022-03-18
Filing date: 2023-03-16
Publication date: 2023-09-21
Also published as: WO2023178278A3; WO2023178278A9

Abstract

A method of manufacturing a molded fiber part includes drawing a fiber slurry onto a forming mold to form a partially-formed molded fiber part. The forming mold includes a forming mold reference dimension along a first axis of the partially-formed molded fiber part. The partially -formed molded fiber part is inserted into a press mold. The press mold includes a press mold reference dimension along the first axis of the partially -formed molded fiber part, wherein the press mold reference dimension is greater than the form mold reference dimension. A compressive pressure is applied to the partially-formed molded fiber part with the press mold, so as to expand the partially -formed molded fiber part towards the press mold reference dimension.

Description

MOLDED FIBER PART PRODUCTION LINES USING TRIMLESS FORMING AND PRESSING MOLDS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is being filed on March 16, 2023, as a PCT International application and claims the benefit of and priority to United States Application No. 63/321,378, filed on March 18, 2022, titled MOLDED FIBER PART PRODUCTION LINES USING TRIMLESS FORMING AND PRESSING MOLDS, the disclosures of which are hereby incorporated by reference in their entireties.

INTRODUCTION

[0002] Pollution caused by single use plastic containers and packaging materials is now a recognized worldwide problem. Replacing single use packaging with biodegradable and compostable materials is proposed as one way to reduce plastic pollution. However, for a new environmentally -friendly replacement to be successful, it must be competitive in both cost and performance to the incumbent plastic technologies it is to replace.

[0003] By way of brief background, molded paper pulp (also referred to as molded fiber) has been used since the 1930s to make containers, trays and other packages. Paper pulp can be produced from recycled materials such as old newsprint and corrugated boxes or directly from tree and other plant fibers. Today, molded pulp packaging is widely used for electronics, household goods, automotive parts and medical products.

[0004] Molds are made by machining a metal tool in the shape of a mirror image, if you will, of the finished part. Holes are drilled through the tool and then a screen is attached to its surface. The vacuum is drawn through the holes while the screen prevents the pulp from clogging the holes. To make the molded fiber part, the mold is immersed into a slurry of fiber and a pressure gradient is applied and water is drawn through the holes in the mold. Fiber from the slurry' is collected on the screen and, after the fiber layer is formed to a desired thickness, the mold with the molded fiber part is removed from the slurry. The molded fiber part is then disengaged from the mold and may be subjected to subsequent processing (e.g., forming, heating, drying, top coating, and the like). [0005] Molded fiber packaging products can be biodegradable and compostable. However, presently known fiber technologies are not well suited for use in food packaging where the food can come into contact with the packaging, particularly meat and poultry' containers, prepared food, produce, microwavable food containers, and lids and cups for beverage containers.

SUMMARY

[0006] In one aspect, the technology' relates to a method of manufacturing a molded fiber part, the method including: drawing a fiber slurry onto a forming mold to form a partially -fonned molded fiber part, wherein the forming mold includes a forming mold reference dimension along a first axis of the partially -formed molded fiber part; inserting the partially-formed molded fiber part into a press mold, wherein the press mold includes a heating element, and wherein the press mold includes a press mold target dimension along the first axis of the partially -formed molded fiber part, wherein the press mold target dimension is greater than the form mold reference dimension; applying a compressive pressure to the partially-formed molded fiber part with the press mold; applying an elevated temperature to the partially -formed molded fiber part with the heating element, wherein application of the compressive pressure and the elevated temperature expands the partially-formed molded fiber part towards the press mold target dimension and substantially solidifies the partially -formed molded fiber part into the molded fiber part; and removing the molded fiber part from the press. Tn an example, drawing the fiber slurry onto the forming mold includes: drawing the fiber slurry to a first depth proximate substantially the entire forming mold; and drawing the fiber slurry to a second depth proximate a predetermined area of the forming mold, wherein the second depth is greater than the first depth. In another example, the predetermined area is adjacent an outer edge of the partially-molded fiber part. In yet another example, the predetermined area is adjacent an interior feature of the partially- molded fiber part. In still another example, the forming mold includes a porous surface adjacent the forming mold reference direction, and wherein the porous surface extends away from a lowermost surface of the forming mold, and wherein drawing a fiber slurry onto a forming mold draws the fiber slurry to a depth greater than a depth of the fiber slurry adjacent the lowermost surface. [0007] In another example of the above aspect, a portion of the forming mold adjacent the fiber slurry comprises a porosity greater than a portion of the forming mold distal the fiber slurry. In another example, drawing the fiber slurry onto the forming mold comprises drawing the fiber slurry onto a screen disposed adjacent the forming mold. In another example, the press mold target dimension is defined by an outermost extent of the press mold and wherein applying the compressive pressure and the elevated temperature expands the partially -formed molded fiber part to contact the outermost extent of the press mold. In yet another example, the contact between the partially -molded fiber part and the outermost extent of the press mold is about substantially the entire perimeter of the press mold. In still another example, the contact is characterized by an absence of fiber feathering.

BRIEF DESCRIPTION OF DRAWINGS

[0008] Various aspects of at least one example are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide an illustration and a further understanding of the various aspects and examples, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of a particular example. The drawings, together with the remainder of the specification, serve to explain principles and operations of the described and claimed aspects and examples. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure.

[0009] FIG. 1 depicts a schematic of an example molded fiber part production line. [0010] FIG. 2 depicts an example of a forming station.

[0011] FIG. 3 depicts a partial schematic view of a forming station and part transfer system in mating engagement.

[0012] FIG. 4 depicts a partial schematic view of a forming mold of the forming station of FIG. 3.

[0013] FIGS. 4A and 4B depict a perspective view and a partial enlarged perspective view, respectively, of a mold for a forming station.

[0014] FIG. 5 depicts a perspective view of a press station. [0015] FIG. 6 depicts a partial schematic view of two molds of a press station in mating engagement.

[0016] FIGS. 6A and 6B depict partial schematic views of two molds of a press station in a pressing operation.

[0017] FIG. 7 depicts a method of forming a molded fiber part.

DETAILED DESCRIPTION

[0018] Before the production line improvements for producing molded fiber products are disclosed and described, it is to be understood that this disclosure is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments of the production line and components thereof only and is not intended to be limiting. It must be noted that, as used in this specification, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a step" may include multiple steps, and reference to "producing" or "products" of a step or action should not be taken to be all of the products.

[0019] Various embodiments of the technology described below relate to the manufacture of fiber-based or pulp-based products for use both within and outside of the food and beverage industry. By way of non-limiting example, the present disclosure relates to the automated, efficient, high-speed production of fiber-based containers. The fiber-based products are adapted to replace their plastic counterparts in a wide variety of applications such as, for example: frozen, refrigerated, and non-refrigerated foods; medical, pharmaceutical, and biological applications; microwavable food containers; beverages; comestible and non-comestible liquids; substances which liberate water, oil, and/or water vapor during storage, shipment, and preparation (e.g., cooking); horticultural applications including consumable and landscaping/gardening plants, flowers, herbs, shrubs, and trees; single-use or disposable storage and dispensing apparatuses (e.g., paint trays, food trays, brush handles, protective covers for shipping); produce (including human and animal foodstuffs such as fruits and vegetables); salads; prepared foods; packaging for meat, poultry, and fish; lids; cups; bottles; guides and separators for processing and displaying the foregoing; edge and comer pieces for packing, storing, and shipping electronics, mirrors, fine art, and other fragile components; buckets; tubes; industrial, automotive, marine, aerospace and military components such as gaskets, spacers, seals, cushions, and the like; and associated molds, wire mesh forms, recipes, processes, chemical formulae, tooling, slurry distribution, chemical monitoring, chemical infusion, and related systems, apparatus, methods, and techniques for manufacturing the foregoing components.

[0020] An existing production line for manufacturing molded fiber parts or products is described in Chinese Patent Application No. 201711129438. X (hereinafter, “the ‘438 application”), entitled “Flexible Production Line for Producing Pulp Molded Products,” which is hereby incorporated by reference herein in its entirety. The ‘438 application describes generally a forming station that includes a former that creates a wet part by dipping a first mold into a tank of fiber slurry, drawing fiber onto the mold until a desired amount of fiber is collected on the screen, and then removing the mold with the attached fiber layer from the slurry. In the system described in the ‘438 application, the forming station also subjects the wet part to a forming operation in which the first mold with the attached layer of fiber is pressed into a second mold after it is removed from the slurry. This forming operation removes some waler from the wet part and contours the surface of the wet part opposite the first mold. In the production line of the ‘438 application, after the molded fiber part is created by the forming station, it is then pressed in a pressing station. The pressing station may be a plurality of pressing stations, operating in parallel. In one example of the ‘438 application, four pressing stations are utilized. Each of the four pressing stations in the ‘438 application includes a single press. Parts are sent to a stacking station after pressing. The forming station, pressing stations, and stacking station are arranged in a circle around a centrally located robot controlling an extendable robotic arm. The robot and robotic arm are configured to remove formed parts from the forming station and transfer them to any one of the four pressing stations. The robotic arm is further configured to remove pressed parts from any the pressing stations and transfer them to either a different one of the pressing stations or to the stacking station. Although the application depicts a number of basic components and stations of a molded fiber part manufacturing line, it unfortunately displays a number of inefficiencies. [0021] Other systems for manufacturing of molded fiber products are described elsewhere. For example, systems are that depict multiple lines of production, hot presses, forming stations, and other stations to improve the production of such parts are described in PCT Application No. PCT/US2020/031675, filed May 6, 2020, and entitled “SYSTEMS AND METHODS FOR PRODUCING MOLDED FIBER PRODUCTS”; and PCT Application No. PCT/US2020/031667, filed May 6, 2020, and entitled “MOLDED FIBER PART PRODUCTION LINES HAVING HIGH OUTPUT AND REDUCED CYCLE TIMES” The disclosures of both of these applications are hereby incorporated by reference herein in their entireties. For illustrative purposes in this application, an example system that may benefit from the technologies described herein is described below in FIG. 1.

[0022] FIG. 1 depicts a schematic of an example molded fiber part production line 100. The line 100 is depicted having a number of stations and systems for moving partially -formed and formed parts between various stations of the line 100. The various stations and systems, as well as particular configurations of the line 100 itself, are descnbed further herein. A forming station 102 includes generally a forming mold, a slurry tank, and an actuation system that moves the forming mold relative to the slurry tank (typically by lowering the mold into the slurry tank). Forming stations are available, for example, from Nanya Pulp Molding Equipment Co., Ltd., of Guangzhou, China. The slurry tank includes a fiber slurry that includes wood fibers in a liquid. The forming mold itself includes a number of vacuum channels that are connected to a vacuum source. The forming mold may have a number of discrete molds for making, typically, a plurality of identical fiber parts, although forming molds that are used to form different parts are also contemplated. In an example, the forming mold may include a mold body or plate that includes the required contours, features, etc., for a particular product. The vacuum channels of the mold body may have deliberate paths or layouts within the mold body, or may be formed randomly therein as part of the mold manufacturing process. Some mold bodies may include thereon a screen or mesh that forms the surface upon which the fibers are drawn during the forming process. In use, the actuation system lowers the forming mold into the slurry tank and the associated vacuum source is activated. This draws the slurry liquid into the vacuum channels, thereby leaving fibers disposed on the surface of the forming mold or the mesh, if present. When a desired amount of fibers are draw n onto the surface or mesh, the actuation system raises the forming mold from the slurry. At this point in the process the fibers disposed on the forming mold are referred to herein as a partially- molded fiber part, in that it includes the general contours and features of a finished molded fiber part, but does not display the performance characteristics of a finished part.

[0023] The partially -formed molded fiber part may then be removed from the forming mold for further processing. This operation may be performed by a part transfer system 104 including a part transfer feature that may be a part transfer mold that substantially corresponds to or is compatible with the fomiing mold. In that regard, the part transfer mold also performs a function of forming surfaces of the partially -molded fiber part disposed opposite the surfaces of the partially-molded fiber part that contact the forming mold. The part transfer mold may also include or define a number of vacuum channels (as described above in the context of the forming mold) that are connected to a vacuum source. In use, the part transfer mold is positioned so as to contact the partially-formed molded fiber part. This contact forms the opposite surface of the partially-formed molded fiber part. Upon actuation of the vacuum source, the partially -formed molded fiber parts are removed from the forming mold. The part transfer system 104 includes a conveyance system that moves the part transfer mold from the forming station 102 to a downstream station, in this case, a press station 106. In that regard, the forming station 102 and the press station 106 may form the terminal ends of a range of motion of the part transfer system 104, which in examples may be referred to as a first position and a second position, respectively. Depending on the cycle time of the forming station 102 and the press station 106, the second position may be an intermediate wait station where the part transfer feature may be positioned to wait for the press station 106 to become available.

[0024] The production line 100 includes a press station 106. The press station 106 utilizes a combination of compressive pressure and elevated temperature to substantially solidify the partially-formed molded fiber part into the molded fiber part (which meets the general performance requirements to be used). The part transfer system 104 may transfer the partially -formed fiber part to the press station 106 (as depicted by arrow 112). The press station 106 includes two molds, referred to generally as a core mold and a corresponding and compatible cavity mold. Regardless of terminology used, the core mold and cavity mold form the two generally opposing surfaces of a formed fiber part. These two molds are generally similar in construction to the forming mold and transfer mold described above as required in order to form the partially -formed fiber part into the formed fiber part. As such, the transfer 112 may occur by the part transfer feature of the part transfer system 104 substantially mating with either of the core mold or the cavity mold. Vacuum channels may be formed in either or both of the core mold and cavity mold and connected to a dedicated vacuum source. The vacuum source for the mold in engagement with the transfer feature during transfer 112 may be activated so as to transfer the partially -molded fiber part to the appropriate mold of the press. Heating elements may be disposed in either or both of the core mold and cavity mold. The core mold and cavity mold are moved relative to each other by a press actuation system that in examples is a hydraulic press. As the press actuation system decreases the separation distance between the core mold and the cavity mold (with the partially -formed fiber part therebetween), the increased compressive pressure helps form the part into the molded fiber part. The increased compressive pressure squeezes additional liquid from the partially-formed fiber part, which may be removed from the press station by one of more vacuum sources connected to the vacuum channels present in either or both of the core mold and the cavity mold. Further, the elevated temperature generated by the heating elements helps to further form and dry the partially-formed fiber part until a part more consistent with the formed fiber part is produced therefrom.

[0025] A removal system 114 removes the molded fiber parts from the press station 106. The removal system may include a removal feature that includes a plurality of vacuum channels. The removal feature may be in the form of a removal mold configured to be compatible with the either of the core mold and the cavity mold. The vacuum channels, in that case are in communication with one or more ports on the surface of the removal mold such that vacuum pressure may draw the formed fiber part off of the core mold or cavity mold. In another example, the removal feature may be a plurality of vacuum cups connected to the vacuum channels. Vacuum pressure applied to the channels by the vacuum source may also remove the formed fiber part from the core mold or the cavity mold. The removal system 114 includes a conveyance mechanism that moves the removal feature from the position in engagement with the particular mold of the press station to a downstream station. Downstream stations in this context may be one or more of a waste station 118, a print station 122, a quality control station 124, and a stacking station 126, each of which are described below. [0026] A waste station 118 is downstream of the removal system 114. The waste station 118 may include a system for capturing molded fiber parts that are known or suspected to be not usable, from the removal system and reintroducing those parts into the slurry system. In an example, the waste station may be a bin, chute, or other structure into which the part may be released from the removal system 114. In certain configurations, part vacuum pressure may be released to discard damaged or otherwise undesirable parts to the waste station 118.

[0027] Subsequent to the waste station 118, the molded fiber part is considered generally sufficiently formed for use. However, other downstream stations may be utilized to add graphics, logos, or other visual information to each molded fiber part, check the quality of the finished parts, or stack or otherwise pack the molded fiber parts for delivery. As such, a downstream print station 122, a quality control station 124, and a stacking station 126 are depicted. These optional stations are described in further detail below.

[0028] The entire production line 100 may be automated and controlled by a control system 128 as shown. The control system 128 may be connected to, and control the operation of, each station and even subcomponents of each station, as well as the transfer and removal systems (in the form of conveyors, robots and other devices, as described elsewhere herein). As discussed further below, the control system 128 may monitor the operation and conditions on the production line 100 continuously and adjust operation to ensure proper functioning and quality of the final parts.

[0029] Control of all operational parameters is anticipated to improve the quality of the formed fiber parts and increase yield of the production line 100. To obtain such control, a sensor network throughout the production line 100 is contemplated. In an example, various sensors are provided at each station and on each conveyance system to monitor any pertinent parameter of the operation of the production line 100. The temperature control of the heated molds of the press station is one example of such monitoring. Signals from such sensors may be sent to and processed by the control system 128. As another example, the press station 106 may be dynamically controlled based on sensors in the station 106. That is, the press station 106 may be operated until a desired state in the formed fiber part is obtained. In an example, one of the molds in the press station 106 may be provided with one or more sensors that monitor, directly or indirectly, a state of the formed fiber part. For example, a temperature sensor on the surface of the mold could be provided to monitor a temperature of the formed part at a location where it contacts the mold. Similarly, a pressure sensor, a humidity sensor, a light emitter/sensor pair, a conductance sensor, an electrode or electrodes monitoring the flow of current through the formed part, or any other such monitoring device or devices could be provided at one or more locations on the mold. Based on the output of the sensors, the time allotted to press the formed part could be dynamically controlled by the control system 128. For example, upon reaching a desired temperature (e.g., a predetermined temperature threshold) as determined by a temperature sensor, the pressing operation may be terminated.

[0030] Such monitoring sensors are not limited to being located in or on the press station 106 and could be located at any place in the production line 100. In one example, white water flow associated with the forming station 102 could be monitored via one or more flow sensors. This allows the flowrate and quantity of white water removed from the partially -formed fiber part to be monitored over time throughout the various stations of the entire production line 100. This allows, e.g., the press station, to be controlled based on the quantity and flow rate of water observed during the operation. Upon determining that the water flow rate or quantity have reached a predetermined threshold (e.g., the flow rate has dropped by 90% since the start of the operation, or after collecting 10 ml of water from the part during a pressing operation), the pressing operation may be terminated regardless of how long the operation has taken.

[0031] Such monitoring data could also be used to do more than simply control how long the press station 106 or any other component operates. In an example, the press station 106 could increase or decrease pressure dynamically based on the data collected. In this way, it is conceivable that any controlled operational parameter (e g., press operation time, press pressure, mold temperature, slurry temperature, vacuum pressure, slurry flow rate, slurry quality, mix tank temperature, conveyor speed or temperature, dryer temperature, ink flow rate, or any other operational setting related to time, temperature, pressure, or movement of a component of the production line) could be controlled in response to data obtained from the one or more sensors.

[0032] The production line 100 in FIG. 1 may be operated in a continuous mode. The various stations and part transfer systems may be continuously moving and parts on the production line 100 are pressed, printed, and dried while in motion. For example, the quality control station may be a simple pass-through station through which a conveyor passes while the parts are tested, as described herein. The printing station may be one or more movable or fixed print heads that print onto the part as the part passes under the print heads.

[0033] Other configurations are also possible. For example, a semi-continuous configuration could be provided in which one or more of the stations removes the part from the production line 100 for some period of time and then replaces it when a subsequent station’s operation is complete. In a different semi-continuous configuration, the part transfer system 104 may operate in a stop-start mode in which, on a presenbed schedule, the part transfer system 104 moves a predetermined distance and stops. In this way, each part is moved between stations over time. In an example, one or more of the part transfer system 104 and removal system 114 may have part transfer features in the form of molds, such as core molds as described herein, incorporated into the appropriate system 102, 114. The molds may provide positive retention of the parts during movement thereof. The press stations could then have the outside mold which receives the part when it reaches the station.

[0034] The production line 100 in FIG. 1 has several advantages. It has inherent expandability in that multiple parallel press stations 106, waste stations 118, and other stations may be operated simultaneously, with a part transfer system 104 and a removal system 114 serving the various stations. In such parallel configurations, each of the parallel portions may be referred to as “sub-lines.” In another example, each of the parallel sub-lines may be dedicated to a different customer having different printing requirements, finished part requirements (thus different pressing and/or drying requirements). Further, as another example, multiple stacking stations 126 would allow for the different customer parts to be stacked separately in an easily automated fashion. The parallel configuration of multiple sub-lines adds resilience to the production line 100 in that any one station in the sub-lines could fail without bringing the entire production line 100 to a stop. Further resilience could be provided by including a second forming station 102. At any given time, different sub-lines may be taken out of operation without affecting the operation of the other sub-lines. Thus, a sub-line dedicated to a specific product may be inoperative until that product is needed, meaning that retooling time can be eliminated.

[0035] FIG. 2 depicts an example of a forming station 200. Specifically, as shown in FIG. 2, the forming station 200 includes a frame 211 on which a lower portion 212 and an upper portion 213 are provided. The upper portion 213 includes a shuttle 231 (corresponding in this case to the part transfer system described above) having an actuation mechanism 233 that allows for raising and lowering of a transfer feature, in this case, a transfer mold 232. A dedicated vacuum source fixed to the shuttle 231 is not visible in the figure. A cylindrical rotating shaft 223 is rotatably connected to the middle of the frame 211 between the lower portion 212 and the upper portion 213 via a rack mount 228. The shaft 223 has a rotation angle of less than 360° and the cylindrical rotating shaft 223 rotates back and forth. At both ends of the cylindrical rotating shaft 223 is an elbow 226. The two ends of the rotating shaft 223 are fixed on the frame by the rotating shaft seat, and the gears 227 are respectively sleeved on both ends of the cylindrical rotating shaft 223, and the two sides of the middle portion of the frame 211 are provided with a translational connection with the gears 227. Attached to the cylindrical rotating shaft 223 are two opposing, symmetrical forming molds 224a, 224b. In this example, the two molds 224a, 224b include mold plates 230 (only visible on the upper portion 213) having core molds formed thereon and provided with screens onto which the fiber is drawn when the molds are in the lower forming chamber 221, or slurry tank. In FIG. 2, the lower mold 224b is in the slurry tank 221, referred to as the forming position, and the oppositely located upper mold 224a is facing upwards towards the shuttle 231 and the transfer mold (a cavity mold) 232 carried thereon.

[0036] The two core molds 224a, 224b are rigidly connected to the rotating shaft 223 by several tubes 225. These tubes 225 and hollow shaft 223 are connected to a vacuum pump system. The tubes are further connected to the penetrations in the molds 224a, 224b. The vacuum pump system creates the pressure differential that pulls the slurry towards the mold 224, thus causing the fiber to build up on the screened surface of the mold. As mentioned above, the two core molds 224a, 224b are symmetrical. This allows them to be rotated about the axis of rotating shaft 223 by rotating the shaft 223, thus quickly moving the molds between the lower portion 212 and an upper portion 213. The fiber slurry bath is contained in the slurry tank 221. When a mold 224 is in that tank 221 as illustrated in FIG. 2, the fiber is deposited on the mold 224 as the slurry is drawn through the mold 224 by the vacuum pump system, thus creating the partially- formed fiber part (not shown) on the mold 224. In one example of the forming station 200, after the appropriate amount of fiber is drawn onto the mold 224 to the desired thickness, the slurry tank 221 is lowered from the mold 224 by an actuation system in the form of a vertical lift 222, freeing the mold 224 to be moved to the upper portion 213 position. The mold 224 and partially-formed fiber part can then be rotated to the upper portion 213 position. The upper portion 213 includes transfer mold 232 attached to the actuation mechanism 233. Activating the mechanism 233 causes the transfer mold 232 to press against the upward-facing lower mold 224a. The mechanism 233 may include one or more of a hydraulic cylinder, a servomotor, a gas cylinder or any other known lifting device. By pressing the mold 224 and mold 232 together, water may be driven out of the partially-formed fiber part and collected through the inner mold 224 via the shaft 223. Upon completion of the pressing operation, a suction is applied to the partially -formed fiber part through penetrations in the mold 232, and the mold 232 is retracted by the mechanism 233 onto the shuttle 231 for movement to a downstream station. This frees the mold 224 to be rotated to the lower portion 212 for the entire forming process to be repeated.

[0037] In an example, the press operation performed by the transfer mold 232 is operated at a selected pressure for a fixed period of time that is equal to the time that is taken for the formed part to be drawn onto the mold at the lower portion 212. In an alternative embodiment described in greater detail below, the pressing time is dynamically controlled based on monitoring data from sensors at one or more locations on the upper portion 213. In an alternate example of the forming station 200, the slurry tank 221 may also include a movable outer mold (not shown) in the tank 221. In this embodiment, after the fibers from the slurry are drawn onto the mold 224, this outer mold may be pressed against the mold 224 while in the slurry tank 221. This provides an additional pressing operation to the partially-formed fiber part, so that the parts exiting the former 200 will have been subjected to two pressing operations instead of just one as with the previous example. Regardless, after the partially -formed fiber part is created and removed from the inner mold 224 by the transfer mold 232, the shuttle 231 transfers it to another station in production line. In another example, the transfer mold 232 may be located at the end of a robotic arm that extends into the upper portion 213 and receives the part when the transfer mold’s 232 suction on the partially-formed fiber part is activated. This is but one example of how the transfer of parts via the robotic arm may be effected Many such methods and systems are known in the art and any suitable method and mechanism may be used in the forming station 200, the robotic arm or any other component of the production lines described herein.

[0038] FIG. 3 depicts a partial schematic view of a forming station and part transfer system in mating engagement 300. The forming station 302 includes a forming mold 304, in this case in a core mold configuration. As used herein, the term “core mold” means a mold having features that substantially project away from the mold plate so as to form a “core” about which the fiber part 306 is at least partially surrounded. The part transfer system 308 includes a part transfer feature, in this case, in the form of a part transfer mold having a cavity mold configuration. As used herein, the term “cavity mold” means a mold having features that substantially project inward into the mold plate so as to form a “cavity” into which the fiber part 306 and core mold extend. Each of the forming mold 304 and the part transfer mold 310 define at least one (but usually a plurality) of vacuum channels 312. The vacuum channels 312 are each connected to a dedicated vacuum source 314, the function of which is described above. It should be noted that a similar mating engagement is utilized when a removal system (described above) engages with a mold of a press station.

[0039] FIG. 4 depicts a partial schematic view of a forming mold 400 that may be utilized in the forming station 300 of FIG. 3. The forming mold 400 may correspond (as to location and general operation) to the forming mold 304 depicted in FIG. 3. Forming molds of various constructions are known in the art. For example, a forming mold fabricated from a solid core may be utilized. Such solid core forming molds may include a screen or mesh material disposed on a mold surface thereof. The screen or mesh material provides a substrate onto which the fiber slurry may be draw n during forming operations, while desirably distributing vacuum pressure as required or desired for a particular application or part. In FIG. 4, the forming mold 400 may be manufactured of 3D printed material or other material that can provide structural integrity while customizing the porosity therein (and therefor the amount of vacuum that may be drawn through the mold, so as to collect the fiber slurry thereon). Such systems and methods that incorporate 3D printed forming molds are described in PCT Application No. PCT/US2021/052731, filed September 29, 2021, entitled POROUS MOLDS FOR MOLDED FIBER PART MANUFACTURING AND METHOD FOR ADDITIVE MANUFACTURING OF SAME,” the disclosure of which is hereby incorporated by reference herein in its entirety. The mold 400 may include areas of greater porosity 420 (e.g., adjacent the areas where a fiber flurry 424 may be drawn) or less porosity 422 (e.g., near the exterior portions of the mold 400), which ultimately controls the amount of vacuum drawn from certain areas of the mold 400. In the depicted example, mold volumes of greater porosity 420 are depicted with a hexagonal or honeycombed cross section, while volumes of less porosity 422 are shaded. As can be seen the porous portions 420 are interconnected and disposed generally below the location of the mold 400 onto which the fiber slurry 424 will be drawn. Further, the porous portions 420 may extend upward along the wall dam 426 or sides of the forming mold 400, generally to a maximum height as indicated. In such a configuration, the fiber slurry 424 is drawn towards both the lower surface of the forming mold 400, as well as to the sides of the forming mold 400. By drawing the slurry 424 towards the sides of the mold 400, an excess amount of slurry 428 may collect and cling to and upwards along the sides. This excess amount of slurry 428 collected at the side is then leveraged in subsequent processes to form a clean edge of the formed fiber parts made with the disclosed technology.

[0040] When measured from a common lowest point of the mold 400, the slurry 424 may be draw to a first depth proximate substantially the entire mold 400. This depth may be that required to make a molded fiber product having a desired nominal thickness. Adjacent certain areas of the mold 400, however, the slurry 424 may be drawn to a second depth (as again measured from the common lowest point of the mold 400), so as to enable the formation of the clean edge as described herein. Typically, to draw the slurry 424 to a greater height in certain locations, drawing the slurry 424 onto one or more substantially vertical surface(s) would be desirable. Such surfaces may be proximate the sides of the mold 400 or adjacent certain internal features.

[0041] The technologies described herein enable formation of a molded part having a sharp edge, without the need for trimming of excess material thereon which may seep outward from the hot press during a pressing operation, such as described herein.

[0042] In one example, the partially -formed molded fiber part 424 (e.g., as formed in the forming mold 400) has a formed dimension generally less than that of the finished molded fiber part (upon exit from the hot press, described below). With reference to FIG. 4, the forming mold 400 may be described as having a forming mold reference dimension DREF which, for the purposes of illustration, may have a width of 82.0 cm depicted in FIG. 4. As the various molded fiber parts formed with the technologies described herein may take any desired shape, the reference dimension DRF is identified relative to a predetermined first axis of the formed fiber part itself. For example, if the molded fiber part 424 has a substantially square shape, the predetermined first axis may extend from one comer, across the center, and to an opposing comer. If the molded fiber part is off-round (e.g., elliptical or partially elliptical), the predetermined first axis may correspond to the major or minor axis, as those terms are understood in the art. In another example, the predetermined first axis may correspond to a diameter of a molded fiber part having a round configuration. In sum, the predetermined first axis is along a known axis of the product, such that the dimension of the part along that axis is known as it is removed from the forming mold, when it is in the partially-formed stage of manufacture. For illustrative purposes, a target dimension DTAR of the finished formed fiber part (e.g., after being subject to a pressing operation described below) is also depicted and is ultimately larger (e.g., 84.0 cm) along the predetermined first axis of the formed dimension as the part exits the forming mold 400 as a partially-formed molded fiber part. In order to enable the expansion of the fiber part 424 during the pressing operation while still maintaining a sharp edge, additional material (e.g., excess slurry 428) is collected at a location where the sharp edge is desired, when the fiber slurry is collected in the forming mold. Such locations may be proximate the outer edge of a fiber part, or at an internal opening, as depicted. The additional material 428 collected at the specific locations at the forming stage is them, during a subsequent pressing operation is pressed in a controlled manner to form a sharp edge against a feature in the press mold. FIG. 4 depicts additional slurry 428 collected at outer edges of a part, but may also be collected proximate an internal location as well, such as the porous post 430 depicted in FIG. 4.

[0043] FIGS. 4A and 4B depict a perspective view and a partial enlarged perspective view, respectively, of a forming mold 400 for a press station. FIGS. 4A and 4B are described concurrently and depict one method of collecting additional fiber slurry at a desired location. The forming mold 400 (depicted inverted in FIGS. 4A and 4B) is formed from a machined unitary part 402 or from a porous molded unitary part, both of which are covered by a mesh material (not shown) to prevent drawing of the fiber slurry into the mold itself. If a machined unitary part is utilized, a number of vacuum channels formed in the part 402 may be communicatively coupled to ports 410 on the surface of the cavity 404 to draw the fiber slurry, under vacuum, onto the mesh during forming operations. As described above, the forming mold 400 may also be formed on a material that is more porous at locations where it is desirable to collect the fiber slurry. One such location may be a perimeter wall or wall dam 406, which defines the outermost extent of the cavity 404.

[0044] As described above, the forming mold 400 may be configured so as to draw fiber slurry higher along the wall dam 406. By drawing the fiber slurry higher up the wall dam 406, the excess fiber may more easily fill larger gaps at the outer perimeter of a press mold during pressing operations. In examples, the forming mold 400 may be configured so as to draw the fiber slurry to level A, level B, or level C, as depicted in FIG. 4. For example, the wall dam 406 may be more porous up to the desired level. Formed fiber parts typically have a nominal thickness as required for a particular application of the part. The thickness of the fiber where a sharp edge is desired will be, in one example, thicker than the nominal thickness of the fiber as drawn onto the forming mold. During pressing operations, however, the part itself and the desired sharp edge portions of the part will be compressed to the same nominal finished thickness, which is less than the thickness of the slurry during forming, whether at the edge or otherwise. In another example, the fiber slurry may be drawn onto a portion of the forming mold that is disposed at an angle to an adjacent surface thereof. The angle may be greater than 0°, for example, about 5°, about 10°, about 15°, about 20°, about 25°, about 30°, about 35°, about 40°, about 45°, about 50°, about 55°, about 60°, about 65°, about 70°, about 75°, about 80°, about 85°, about 90°, or at ranges bounded by the above degrees, for example. The angled surface may extend vertically above or vertically below the adjacent surface. This creates a greater volume of slurry that may be pressed into a smooth edge during pressing operations. For illustrative purposes, it should be noted that the angled surface in FIG. 4 corresponds to the wall dam, which is disposed at about a positive 90° angle to the bottom surface upon which the fiber (wet formed part) collects in the forming mold.

[0045] FIG. 5 depicts a perspective view of a press station 500. The station 500 includes a press mechanism 502 that includes an upper mold 506 and a mating lower mold 508. The lower mold 508 in this case is referred to as a core mold because of the presence of projecting features 516 that form the forming core of the molded fiber part. The upper mold 506, in contrast, is referred to as a cavity mold because of a cavity formed therein to receive the projecting features 516 and the molded fiber part during press operations. In other examples, the location of the core and cavity molds may be reversed. The upper mold 506 and lower mold 508 may include one or more individual plates that are used to form the particular formed packaging product. In the depicted example, six plates each are used in the upper mold 506 and lower mold 508, although other numbers of molds are contemplated. By using multiple plates per mold, the throughput of the production line is increased. In this example, a press station 500 has six plates, although one, two, four, eight, ten, or more plates may be used. While odd numbers of plates may be used, even numbers of plates are more typical. This increases the throughput for a press station 500 (as well as other stations within the production line) within only an incremental increase in the cost of the equipment.

[0046] The press mechanism 502 is supported on a fixed base 510. The press mechanism 502 includes a movable plate 512, to which is secured to the upper mold 506. This movable plate 512 is configured to slide along a plurality of rails 515, when actuated by a piston 516. Actuation of the piston 516 drives the movable plate 512 (with the upper mold 506 located thereon) towards the base 510. A single pressurized fluid chamber 518 may be connected by pipes 520, valves, and other known elements to the piston 516. A controller 522 may be programmable and communicatively coupled to a controller for the robot (not show n ) or shuttles that form a part of the production line (not shown) so as to control the station 500 as required or desired for a particular application. In applications, either or both of the upper mold 506 and lower mold 508 may be heated so as to properly form the molded fiber products. Such heating elements are described elsewhere within the present application.

[0047] FIG. 6 depicts a partial schematic view of two molds of a press station 600 in mating engagement. The press station 600 includes a lower mold 602, in this case in a core mold configuration. An upper mold 604 is in the form of a part transfer mold having a cavity configuration. The terms “core mold” and “cavity mold” are described above. A fiber part 606 is disposed between the lower mold 602 and the upper mold 604. Each of the lower mold 602 and the upper mold 604 define at least one (but usually a plurality of) vacuum channels 608. The vacuum channels 608 are each connected to a dedicated vacuum source 610, the function of which is described above. In other examples, the lower mold 602 and upper mold 604 may be formed of a porous material, such as described above in the context of FIG. 4. Each of the lower mold 602 and the upper mold 604 each include a heating element 612. In the case of a dedicated press station 600, the elements 602-612 are utilized.

[0048] Improved control of temperature during the operation of the press station 600 is anticipated to improve the quality of the formed fiber parts and increase yield of the production line. In one example, each mold 602, 604 is provided with an internal heating element 612. The element 612 may be a simple internal passage through which a heated fluid may flow. In an alternative example, a resistive heater may be built into each mold 602, 604. Heating elements 612 are known in the art and any suitable heating technology, now know n or later developed, may be used. Examples of a heated mold 602, 604 may be further provided with one or more temperature sensors T. The temperature sensors T may monitor the temperature in the mold 602, 604, of the surface of the mold 602, 604, of the fiber part 606, or at any other location in, on, or near the mold 602, 604. Furthermore, for more fine control of temperature, a mold 602, 604 may be divided into multiple segments, or sectors, and the temperature of each segment may be independently monitored and controlled.

[0049] Prior solutions to form a clean edge on a molded fiber part included additional trimming components in the press station 600 (a so-called “combination press-trim station,” as depicted in FIG. 6), or in a dedicated trim station (not shown). In a combination press-trim station 600a, elements 602-612 are still utilized, but a trimmer 614 may also be used in conjunction with either or both of the lower mold 602 and the upper mold 604. The trimmer 614 may be a discrete element, as in the depicted example. As the lower mold 602 and the upper mold 604 are brought into compressive contact, outer edges of the molded fiber part 606 press outward. If uncontrolled, this may cause a “feathering” appearance at the edge, where the fiber slurry randomly escapes from the mold, leading to an uneven edge. As such, the trimmer 614 is configured to press down upon this feathering, thereby cutting or pressing through any material disposed outside of a predetermined portion of the molds 602, 604. This separates waste trim from the molded fiber part 606. There are, however, some disadvantages in such systems that utilize mechanical trimmers. Portions cut from the molded fiber part 606 may get caught in the press mold which may affect parts subsequently formed in the press station 600a. During pressing operations, the slurry material is subjected to heating which effectively melts at the surface where the material of the part contacts the hot press, thus forming a seal that resists moisture infiltration. Trimming subsequent to pressing may compromise this seal, thus exposing the part to infiltration and degraded performance.

[0050] As such, the technologies described herein, in conjunction with the forming mold of FIG. 4, contemplate a press station having dimensions that enable pressing of the partially-formed molded fiber part that expands out to a maximum desired dimension, while maintaining structural integrity. This is depicted in FIGS. 6 A and 6B, where partial schematic views of a lower mold 652 and an upper mold 654 of a press station 650 in a pressing operation are shown. The partially -formed molded fiber part 656 is first disposed within the lower mold 652, as depicted in FIG. 6A. The depicted target finished size or dimension DTAR corresponds to the finished size of the molded fiber part, subsequent to a pressing operation, as defined by an outermost extent of the press mold. The application of the elevated temperature and compressive pressure by the press mold results in contact between the the fiber slurry and substantially the entire perimeter ort outermost extent of the press mold. As can be seen, this target finished size or dimension DTAR is larger than the size of the partially -formed molded fiber part 656, as removed from the former. This target finished size or dimension DTAR is also measured along the same predetermined first axis as identified above with regard to FIG. 4. Put simply, then, the dimensions of the lower mold 652 are larger than that of the forming mold of FIG. 4. The upper mold 654 forms a close fit with the lower mold 652 so as to limit seepage of the material of the partially-formed fiber part during the pressing operation. As the upper mold 654 is lowered and the pressing operation is performed, the higher portions of the material proximate the edges (formed proximate the edges of the forming mold as depicted in FIG. 4) are pressed into the gap or void originally present between the partially-formed fiber part and the lower mold 652, spreading the material into the lower mold 652 and out to the furthest extent thereof, thus forming the finished part 658. Thereafter, the lower mold 652 and upper mold 654 may be disengaged and the molded fiber part removed from the press station.

[0051] FIG. 7 depicts a method 700 of forming a molded fiber part. The method 700 begins with operation 702, drawing a fiber slurry onto a forming mold to form a partially -formed molded fiber part. The forming mold includes a forming mold reference dimension along a first axis of the partially -formed molded fiber part. The method continues with operation 704, inserting the partially-formed molded fiber part into a press mold. As described elsewhere herein, the press mold has a heating element, and a press mold reference dimension along the first axis of the partially- formed molded fiber part. The press mold reference dimension is greater than the form mold reference dimension such that, when a compressive pressure is applied to the partiall -formed molded fiber part, operation 706, with the press mold, the partially- formed molded fiber part expands towards the press mold reference dimension.

Simultaneously, an elevated temperature is applied to the partially-formed molded fiber part with the heating element, operation 708. This elevated temperature substantially solidifies the partially-formed molded fiber part into the molded fiber part. Thereafter, the molded fiber part may be removed from the press, operation 710.

[0052] Other optional operations may be performed in alternative examples of the above method 700. For example, drawing the fiber slurry onto the forming mold may contemplate drawing the fiber slurry to a first depth proximate substantially the entire forming mold, while simultaneously drawing the fiber slurry to a second depth proximate a predetermined area of the forming mold, wherein the second depth is greater than the first depth. In examples, the predetermined area is adjacent an outer edge of the partially-molded fiber part, although in other examples, e.g., where a through hole in the molded fiber part is desired, the predetermined area is adjacent an interior feature of the partially-molded fiber part. In another example, the forming mold includes a porous surface adjacent the forming mold reference direction, and the porous surface extends away from a lowermost surface of the forming mold. In such a configuration, drawing the fiber slurry onto the forming mold draws the fiber slurry to a depth greater than a depth of the fiber slurry adjacent the lowermost surface.

[0053] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained.

[0054] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the technology are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0055] It will be clear that the systems and methods described herein are well adapted to attain the ends and advantages mentioned as well as those inherent therein. Those skilled in the art will recognize that the methods and systems within this specification may be implemented in many manners and as such are not to be limited by the foregoing exemplified embodiments and examples. In this regard, any number of the features of the different embodiments described herein may be combined into one single embodiment and alternate embodiments having fewer than or more than all of the features herein described are possible.

[0056] While various embodiments have been described for purposes of this disclosure, various changes and modifications may be made which are well within the scope contemplated by the present disclosure. Numerous other changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the disclosure.

Claims

CLAIMS What is claimed is:

1. A method of manufacturing a molded fiber part, the method comprising: drawing a fiber slurry onto a forming mold to form a partially-formed molded fiber part, wherein the forming mold comprises a forming mold reference dimension along a first axis of the partially -formed molded fiber part; inserting the partially-formed molded fiber part into a press mold, wherein the press mold comprises a heating element, and wherein the press mold comprises a press mold target dimension along the first axis of the partially -formed molded fiber part, wherein the press mold target dimension is greater than the form mold reference dimension; applying a compressive pressure to the partially -formed molded fiber part with the press mold; applying an elevated temperature to the partially-formed molded fiber part with the heating element, wherein application of the compressive pressure and the elevated temperature expands the partially -formed molded fiber part towards the press mold target dimension and substantially solidifies the partially -formed molded fiber part into the molded fiber part; and removing the molded fiber part from the press mold.

2. The method of claim 1, wherein drawing the fiber slurry onto the forming mold comprises: drawing the fiber slurry to a first depth proximate substantially the entire forming mold; and drawing the fiber slurry to a second depth proximate a predetermined area of the forming mold, wherein the second depth is greater than the first depth.

3. The method of claim 2, wherein the predetermined area is adjacent an outer edge of the partially -molded fiber part.

4. The method of claim 2, wherein the predetermined area is adjacent an interior feature of the partially-molded fiber part.

5. The method of claim 2, wherein the forming mold comprises a porous surface adjacent the forming mold reference direction, and wherein the porous surface extends away from a lowermost surface of the forming mold, and wherein drawing a fiber slurry onto a forming mold draws the fiber slurry to a depth greater than a depth of the fiber slurry adjacent the lowermost surface.

6. The method of claim 1, wherein a portion of the forming mold adjacent the fiber slurry comprises a porosity greater than a portion of the forming mold distal the fiber slurry.

7. The method of claim 1, wherein drawing the fiber slurry onto the forming mold comprises drawing the fiber slurry onto a screen disposed adjacent the forming mold.

8. The method of claim 1, wherein the press mold target dimension is defined by an outermost extent of the press mold and wherein applying the compressive pressure and the elevated temperature expands the partially-formed molded fiber part to contact the outermost extent of the press mold.

9. The method of claim 8, wherein the contact between the partially-molded fiber part and the outermost extent of the press mold is about substantially the entire perimeter of the press mold.

10. The method of claim 1, wherein the contact is characterized by an absence of fiber feathering.