CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims the benefit of U. S. Provisional Patent Application No. 62/429,698 filed December 2, 2016, the entire contents of which are incorporated by reference herein.

FIELD OF THE DISCLOSURE

The disclosure relates to an apparatus and method for high-throughput rotational molding processes. More particularly, the disclosure relates to an apparatus and method for high-throughput rotational molding processes involving multiplexed molds.

BACKGROUND

Products made from plastic may be manufactured by a variety of molding processes such as, for example, blow molding, inj ection molding, thermoforming, and rotational molding (also known as rotomolding). Rotational molding may be used to produce hollow articles from plastics such as, for example, thermoplastics. The rotational molding process generally occurs in a series of sequential stages. First, a quantity of material (e.g., a shot weight or charge) to be molded is placed into a hollow cavity mold, which may have any of a variety of designs depending upon the shape of the desired product to be produced. A typical hollow cavity mold may have a two-piece construction that includes a lower mold half and an upper mold half. This stage of the process may be referred to as "charging." Second, the hollow cavity mold is then heated under bi-axial rotation until the material within the hollow cavity mold is melted into successive layers on the inside of the hollow cavity mold to form the desired plastic structure. Third, the hollow cavity mold is then cooled (e.g., by air, water, or a combination of both). Finally, the hollow cavity mold is opened and the final product is removed. This stage of the process may be referred to as "demolding." Unfortunately, conventional rotational molding processes have a relatively low throughput because a single operator typically operates the charging station and the demolding station. Accordingly, there is a need for rotational molding apparatus and methods that enable high throughput capacity.

SUMMARY

In one aspect, the disclosure provides a rotational molding apparatus that includes: a multiplex mold including an upper mold, a lower mold and a plurality of orifices, where the upper mold is configured to be reversibly sealable with the lower mold and the plurality of orifices define a corresponding plurality of molding chambers; and a multiplex swing arm including a pin, at least one swing arm lever, and a plurality of swing arms, where the plurality of swing arms corresponds to the plurality of orifices.

DEFINITIONS

Hereinafter reference will now be made in detail to various embodiments of the subj ect disclosure, examples of which are illustrated in the accompanying drawings and described below. While example embodiments are described, it will be understood that the present disclosure is not limited to those exemplary embodiments. On the contrary, this disclosure covers not only the embodiments described herein, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the disclosure.

Ranges provided herein are understood to be shorthand for all of the values within the range. For example, a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, as well as all intervening decimal values between the aforementioned integers such as, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, "nested sub-ranges" that extend from either end point of the range are specifically contemplated. For example, a nested sub-range of an exemplary range of 1 to 50 may comprise 1 to 10, 1 to 20, 1 to 30, and 1 to 40 in one direction, or 50 to 40, 50 to 30, 50 to 20, and 50 to 10 in the other direction.

Unless specifically stated or obvious from context, as used herein, the term "about" is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. "About" may be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01 % of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term "about."

As used herein, the singular form "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and desired obj ects of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawing figures wherein like reference characters denote corresponding parts throughout the several views and wherein:

FIG. 1 provides a side view of a swing arm mold unit in a rotomolding position according to an exemplary embodiment of the disclosure;

FIG. 2 provides a side view of a swing arm mold unit in a de-molding position according to an exemplary embodiment of the disclosure;

FIG. 3 provides a side view of a swing arm mold unit in a de-molding position with the product removed according to an exemplary embodiment of the disclosure;

FIG. 4 provides a perspective view of a swing arm mold unit in a de-molding position with the product removed according to an exemplary embodiment of the disclosure;

FIG. 5 provides a perspective view of a multiplex swing arm mold unit in a charging position according to an exemplary embodiment of the disclosure;

FIG. 6 provides a perspective view of a multiplex swing arm mold unit in a charging position with a mounted multiplex swing arm according to an exemplary embodiment of the disclosure;

FIG. 7 provides a perspective view of a multiplex swing arm mold unit in a charging position with a mounted multiplex swing arm interfaced with a multiplex mold according to an exemplary embodiment of the disclosure;

FIG. 8 provides a perspective view of a multiplex swing arm mold unit in a molding position according to an exemplary embodiment of the disclosure;

FIG. 9 provides a perspective view of a multiplex swing arm mold unit in a de- molding position according to an exemplary embodiment of the disclosure;

FIG. 10 provides a perspective view of a multiplex swing arm mold unit in a de- molding position with a mounted multiplex swing arm in the raised position according to an exemplary embodiment of the disclosure; and

FIG. 11 depicts a rotational molding process according to an exemplary embodiment of the disclosure.

DETAILED DESCRIPTION

The present disclosure provides an apparatus and method for high-throughput rotational molding processes. The present disclosure is based, at least in part, on the discovery that swing arm methodology may be combined with rotational molding to create scalable, multiplexed molds that may be charged and de-molded in a high-throughput manner. Reference will now be made to the drawings wherein like reference numerals identify similar structural aspects of the subject disclosure.

FIG. 1 depicts a side view of an exemplary embodiment of a swing arm mold unit 100 in the molding position. Swing arm 110 may have a collar 120 positioned proximal to mold unit 105, which may include lower mold 150 and upper mold 160. Swing arm 110 may be connected to a mounting bracket 130 by pin 170. One of skill in the art will appreciate that swing arm 110 may be connected to mounting bracket 130 by any of a variety of connector types that allow rotational movement of swing arm 110 relative to mounting bracket 130 (e.g., a pin, a hinge, a ball joint, and the like). Mounting bracket 130 may be affixed to spider frame 140. Similarly, lower mold 150 may also be affixed to spider frame 140 at a desired distance from mounting bracket 130. The length of swing arm 110 may be varied in a manner that correlates with the distance at which lower mold 150 is located from mounting bracket 130.

As noted above, FIG. 1 depicts an exemplary embodiment of swing arm mold unit 100 in the molding position. In other words, upper mold 160 is coupled to lower mold 150 to form mold unit 105. Upper mold 160 may be reversibly coupled to lower mold 150 by any of a variety of means known to one of skill in the art such as, for example, bolting, pressure fitting, clamping, and the like. Top end 106 of mold unit 105 may have an orifice 210 capable of coupling with swing arm 110 (see e.g., FIG. 4). Collar 120 of swing arm 110 may be configured to abut top end 106 of mold unit 105 very tightly (e.g., via pressure fit, slot fit, or the like) to prevent any liquid plastic from leaking out of top end 106. Bottom end 107 of mold unit 105 may include a centrally located vent hole (not shown) configured to allow pressure within mold unit 105 to equalize during the rotational molding process (e.g., during heating in an oven).

FIG. 2 depicts an exemplary embodiment of swing arm mold unit 100 in the de- molding position. In this position, upper mold 160 may be raised up from, or off of, lower mold 150 and swing arm 110 may be rotated away from lower mold 150, thereby easily removing products 180 from lower mold 150. In the exemplary embodiment shown, swing arm 110 may be rotated approximately 90° away from lower mold 150.

FIG. 3 depicts an exemplary embodiment of swing arm mold unit 100 in the de- molding position with product 180 removed. In this position, the distal most portion of swing arm 110, plug 190, is visible. In an exemplary embodiment, plug 190 may be made of a suitable material to facilitate removal of product 180 such as, for example, Teflon. FIG. 4 provides a perspective view of swing arm mold unit 100 in a de-molding position with the product removed according to an exemplary embodiment of the disclosure. Mounting bracket 130 may be paired with another mounting bracket 130 such that a proximal end of swing arm 110 may be rotatably coupled between each mounting bracket 130 via pin 170. It is contemplated within the scope of the disclosure that pin 170 may be configured to be reversibly coupled to mounting bracket 130. Swing arm lever 200 may be affixed to one end of pin 170. It is also contemplated within the scope of the disclosure, that swing arm lever 200 may be affixed to both ends of pin 170. Swing arm lever 200 may facilitate the ability of an operator to rotate swing arm 110 between the molding and de-molding positions.

FIGS. 5-10 depict several views of an exemplary embodiment of a multiplex swing arm mold unit 300.

FIG. 5 depicts a perspective view of an exemplary embodiment of a multiplex swing arm mold unit 300 in the charging position. Multiplex swing arm 395 may include multiple swing arms 310 connected to pin 370. Each of the multiple swing arms 310 may be configured in a manner analogous to swing arm 110 (see e.g., FIG. 1) to include a collar 320 and a distally located plug 390. A proximal end of each of the multiple swing arms 310 may be configured to attach to pin 370. One of skill in the art will appreciate that the length of pin 370 may be increased or decreased to accommodate any desired number of multiple swing arms 310. Swing arms 310 will generally be positioned so that each of the multiple swing arms 310 are aligned along the lengthwise axis of pin 370. Each end of pin 370 may be configured to rotationally couple with a first mounting bracket 330 and a second mounting bracket 330, as shown in FIG. 6. Pin 370 may further include one or more swing arm levers 400. In an exemplary embodiment, a mounting bracket 130 may be affixed to each end of lower mold 350. Mounting bracket 130 may be configured to receive an end of pin 370 in any of a variety of ways known to one of skill in the art such as, for example, a slot, a hole, a groove, a pressure fit mount, a spring-loaded mount, and the like. The length of swing arms 310 may be varied in a manner that correlates with the distance at which lower mold 350 is positioned relative to mounting bracket 330.

Multiplex swing arm mold unit 300 may include multiplex mold unit 305 (see e.g., FIG. 8), which may further include lower mold 350 and upper mold 360. Lower mold 350 may be affixed to spider frame 340 by any of a variety of fixing methods known to one of skill in the art such as, for example, bolting, welding, etc. Multiplex mold unit 305 may include a plurality of orifices 318 arranged in series. According to the techniques herein, the number of swing arms 310 present on multiple swing arm 395 will correspond to the number of orifices 318 within a particular multiplex mold unit 305. One of skill in the art will appreciate that the number of orifices 318 within multiplex mold unit 305 may be increased or decreased as appropriate for particular applications. In general, the throughput of multiplex swing arm mold unit 300 may increase as the number of orifices 318 increases.

As noted above, FIG. 5 depicts an exemplary embodiment of multiplex swing arm mold unit 300 in the charging position. In other words, upper mold 360 is raised above (or off of) lower mold 350. According to the techniques herein, upper mold 360 may include one or more lifting brackets 362 configured to raise and lower upper mold 360 relative to lower mold 350. Upper mold 360 may be reversibly coupled to lower mold 350 by any of a variety of means known to one of skill in the art such as, for example, bolting, pressure fitting, clamping, and the like. In the charging position, shot may be added to lower mold 350 while upper mold 360 is in the raised position.

As shown in FIG. 6, a multiplex swing arm 395 may be moved from storage rack 420 and slotted into a first and second perspective mounting bracket 330 positioned on lower mold 350.

As shown in FIG. 7, the previously slotted multiplex swing arm 395 may be rotated via swing arm levers 400 into a horizontal position so that plugs 390 associated with each of the swing arms 310 on multiplex swing arm 395 are positioned horizontally within the corresponding orifices 318. In an exemplary embodiment, plug 390 may be made of a suitable material to facilitate removal of product 180 such as, for example, Teflon. Collar 320 on each of the swing arms 310 may be configured to abut orifice 318 of multiplex mold unit 305 very tightly (e.g., via pressure fit, slot fit, or the like) to prevent any liquid plastic from leaking out of orifice 318. Multiplex mold unit 305 may include a centrally located vent hole opposite of each of the orifices 318 (not shown) configured to allow pressure within multiplex mold unit 105 to equalize during the rotational molding process (e.g., during heating in an oven). According to the techniques herein, a new multiplex swing arm 395 may be moved from the cooling rack 430 to the empty slot in storage rack 420.

As shown in FIG. 8, upper mold 360 may be lowered onto lower mold 350 to form multiplex mold unit 305, and multiplex swing arm mold unit 300 may be moved into an oven and bi-axially rotated to begin the rotational molding process. Once the heating process is complete, multiplex swing arm mold unit 300 may be removed from the oven and allow to cool.

FIGS. 9 and 10 depict the de-molding process in which upper mold 360 may be raised off of lower mold 350. In the exemplary embodiment shown, swing arms 310 may be rotated approximately 90° away from lower mold 150, and multiplex swing arm 395 may be rotated into an upward position so that it may be then be transferred to cooling rack 430 for additional cooling.

FIG. 1 1 depicts a rotational molding process according to an exemplary embodiment of the disclosure that utilizes a four-arm rotational molding machine that simultaneously interacts with a charging station, an oven station, a cooling station, and the de-molding station.

Plastics of the present disclosure may include, for example, acrylic, ABS, acetal, epoxy, fluorocarbons, ionomer, nylon, PLA, polybutylene, polyester, Polybenzimidazole, poly carbonate, polyether sulfone, polyetherether ketone, polyetherimide, polyethylene, cross-linked polyethylene (PEX), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), polyphenylene oxide, polyphenylene sulfide, polypropylene, polystyrene, polyurethane, polyvinylchloride, silicone, and Teflon.

Molds of the present disclosure may typically be made of, for example, stainless steel, aluminum, or combinations thereof.

EQUIVALENTS

Although preferred embodiments of the disclosure have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.