Patent Application
20240009898
The invention relates to the field of rotational molding, specifically apparatus and methods for rotationally molding items or objects comprised of plastic or plastic composites.
The process of rotational molding, or rotomolding, has long been used in the manufacturing business to fabricate everything from automotive parts to agricultural storage tanks. Any product which may be too large for other processes such as injection molding which require a hollow interior are often best suited for rotomolding.
Typically, the rotomolding process starts with a hollow mold of the item to be fabricated being filled or charged with plastic which, depending on the type of mold being used, may be in the form of a liquid or powdered resin or a plurality of plastic pellets. The mold is disposed on a mold frame which itself is disposed on a rotational arm which is capable of rotating or spinning the mold frame along at least two different axes of rotation as the mold frame is warmed using an oven or other heating element. The rotation arm continues to spin the mold as the resin or pellets disposed therein begin to melt and then coat the inner surfaces of the mold. After a predetermined amount of time, the mold frame is removed from the oven while the rotational arm continues to rotate the mold. Once sufficiently cooled, the rotational arm stops spinning the mold. The mold is then opened, allowing the now fabricated item to be removed. The entire procedure may then be repeated by then refilling or recharging the mold with new plastic resin or plastic pellets and restarting the rotating and heating process.
While rotational molding can produce nearly any type of product imaginable, a problem develops however when the mold itself needs recharging or when a mold is to be replaced by a different mold within the rotomolding machine so that a different product may be manufactured. Molds used in the rotational molding process need to be thick and as a result are extremely heavy and must be carefully lifted using hoists or cranes each time one is to be removed or installed. Once guided into position, one or more workers must then physically couple the mold to the mold frame by most frequently using a plurality of bolts and a pneumatic wrench. The workers must get extremely close to the mold including often climbing or ducking underneath the mold in order to properly tighten each bolt. This can be highly dangerous for the worker since even a relatively small mold could cause great pain or injury if it fell while the worker was attempting to couple it to its corresponding mold frame. This risk is only increased when multiple products need to be manufactured within a short amount of time and workers must rush each installation or removal process.
What is needed therefore is improved apparatus and method for installing and removing molds from rotational molding machines and devices. The apparatus and method should be easy to use and implement and should increase the overall safety of those workers or employees tasked with recharging or replacing the mold while also reducing any down time for the rotational molding machine whenever a mold is being replaced.
The current invention provides an apparatus for coupling a mold to a rotational molding machine. The apparatus includes an arm plate and a mold plate that is configured to accommodate and rotate about a raised portion of the arm plate that is removably disposed within a body of the mold plate. The arm plate also includes a plurality of hand actuated or manual coupling means that are configured to selectively lock the mold plate to the arm plate.
In one embodiment, the raised portion of the arm plate includes a raised platform while the mold plate includes an opening that is defined within the body of the mold plate which is configured to accommodate the raised platform of the arm plate.
In another embodiment, the apparatus also includes a plurality of rods that are symmetrically disposed on the body of the mold plate as well as a plurality of receivers that are symmetrically disposed on the arm plate, each of the receivers having at least one of the hand actuated or manual coupling means disposed thereon. Each of the plurality of receivers includes a strike aperture that is defined therein which is configured to accommodate at least one of the plurality of rods.
In another embodiment, each of the plurality of hand actuated or manual coupling means includes both a lever and a clasp, where the clasp is configured to capture the mold plate.
In yet another embodiment, the mold plate has at least one mounting bracket that is configured to couple the mold plate to a mold frame and/or a mold.
In a further embodiment, the arm plate also includes means for coupling to a distal end of a rotational arm of the rotational molding machine.
The current invention also provides a rotational molding apparatus which includes a mold, an indexing unit having at least one rotational arm, a mold plate coupled to the mold, and an arm plate coupled to a distal end of the at least one rotational arm. The mold plate itself includes means for selectively engaging the arm plate in order to couple the mold to the at least one rotational arm.
In one embodiment, the means for selective engaging the arm plate in order to couple the mold to the at least one rotational arm includes an aperture defined within a body of the mold plate and a raised platform that is disposed on the arm plate, the raised platform being configured to fit within the opening defined in the body of the mold plate. Here, the mold plate is specifically configured to rotate relative to the arm plate when the raised platform is disposed within the aperture.
In a further embodiment, the means for selectively engaging the
arm plate in order to couple the mold to the at least one rotational arm specifically includes a plurality of rods that are disposed on the mold plate and a plurality of receivers that are disposed on the arm plate, each of the plurality of receivers having a strike aperture defined therein. The means for selectively engaging also include a hand actuated or manual coupling means that are disposed on each of the plurality of receivers. The strike aperture defined in each of the plurality of receivers is configured to accommodate at least one of the plurality of rods therein. Specifically, the hand actuated or manual coupling means of this embodiment may comprise a toggle clamp. Additionally, both the plurality of rods and the plurality of receivers are preferably symmetrically disposed around the mold plate and the arm plate, respectively. Additionally in this embodiment, the toggle clamp may further include a clasp that is configured to fit around a head of at least one of the plurality of rods. The plurality of rods and the plurality of receivers preferably extend radially from a body of the mold plate and a body of the arm plate, respectively.
In yet a further embodiment, the mold and mold plate are specifically configured to rotate around a primary axis and a secondary axis while the mold plate is selectively engaged with the arm plate.
The current invention further provides a method for coupling a mold to a rotational molding machine. The method includes disposing a mold plate that is coupled to a mold over an arm plate that is coupled to a distal end of at least one rotational arm of the rotational molding machine, inserting a platform that is disposed on the arm plate into an aperture defined in a body of the mold plate, and then rotating the mold plate relative to the arm plate. Next, the mold plate is locked to the arm plate.
In one particular embodiment, rotating the mold plate relative to the arm plate specifically includes rotating the body of the mold plate around a circumference of the platform disposed on the arm plate.
In a separate embodiment, rotating the mold plate relative to the arm plate includes rotating a plurality of rods that are radially disposed on the body of the mold plate relative to the arm plate. More specifically, rotating the plurality of rods radially that are disposed on the body of the mold plate relative to the arm plate includes rotating the plurality of rods into a corresponding plurality of receivers disposed on the arm plate, namely by preferably inserting each of the plurality of rods into an aperture that is defined in each of the plurality of receivers. In this embodiment, locking the mold plate to the arm plate specifically includes actuating a coupling means that is disposed on each of the plurality of receivers after the mold plate has been rotated relative to the arm plate. Additionally, the step of actuating the coupling means disposed on each of the plurality of receivers after rotating the mold plate relative to the arm plate preferably includes accommodating each of the plurality of rods with a clasp that is disposed on each of the plurality of receivers and then maintaining the plurality of rods in a fixed position relative to the plurality of receivers.
In yet another embodiment, the method also includes coupling the mold plate to a mold frame.
The current invention further provides a method for manufacturing
an item using a rotational molding machine. The method includes charging a mold with granulated plastic, disposing a mold plate that is coupled to the mold on top of an arm plate that coupled to a distal end of a rotational arm of a rotational molding machine, and then rotating the mold relative to the rotational arm in a first direction. A coupling means disposed on the arm plate is then actuated which locks the mold plate to the arm plate. Next, the rotational molding process is carried out by first heating the mold while rotating the mold along a primary axis and a secondary axis and then cooling the mold while rotating the mold along the primary axis and the secondary axis. After cooling, the item is removed from the rotational molding machine.
In one embodiment, disposing the mold plate that is coupled to the mold on top of the arm plate that is coupled to the distal end of a rotational arm of the rotational molding machine specifically includes aligning an aperture that is defined in a body of the mold plate over a platform disposed on the arm plate and then inserting the platform disposed on the arm plate into the aperture that is defined in the body of the mold plate. More specifically, rotating the mold relative to the rotational arm in the first direction includes rotating the body of the mold plate around a circumference of the platform of the arm plate.
In a separate embodiment, rotating the mold relative to the rotational arm includes inserting a plurality of rods that are disposed on the mold plate into a corresponding plurality of receivers that are disposed on the arm plate as the mold plate is rotated relative to the arm plate.
In yet a further embodiment, the method of step of actuating the coupling means disposed on the arm plate which locks the mold plate to the arm plate specifically includes actuating a plurality of toggle clamps.
In another embodiment, the step of actuating the coupling means disposed on the arm plate includes inserting each of the plurality of rods into a strike aperture that is defined in each of the corresponding plurality of receivers, disposing a clasp that is disposed on each of the plurality of receivers around each of the plurality of rods, and then tightening the clasp disposed on each of the plurality of receivers against a surface of each of the plurality of receivers.
In one embodiment, removing the item from the mold includes actuating the coupling means disposed on the arm plate which unlocks the mold plate from the arm plate, rotating the mold relative to the rotational arm in a second direction, and then lifting the mold plate from the arm plate. The fabricated item is then removed from the mold. Lifting the mold plate from the arm plate may also preferably include removing a platform that is disposed on the arm plate from an aperture that is defined within a body of the mold plate.
While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, are not to be construed as necessarily limited in any way by the construction of “means” or “steps” limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112. The disclosure can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals.
The disclosure and its various embodiments can now be better understood by turning to the following detailed description of the preferred embodiments which are presented as illustrated examples of the embodiments defined in the claims. It is expressly understood that the embodiments as defined by the claims may be broader than the illustrated embodiments described below.
Greater understanding of the current invention and its various embodiments may be had by turning to
The mold plate 16 comprises a substantially rectangular body with a plurality of radial protrusions or spokes 20 emanating from a center of mass of the mold plate 16. Disposed in turn on each of the plurality of radial protrusions or spokes 20 is a bolt or rod 22 which extends horizontally outward from the mold plate 16. Each bolt or rod 22 may also comprise an enlarged cap or head 24 which comprises a slightly larger diameter relative to the rest of the bolt or rod 22. Disposed on an upper or top surface of the mold plate 16 are a plurality of mounting brackets or rails 26. Each of the mounting brackets or rails 26 comprise a plurality of apertures which permit a number of bolts, screws, or other means for coupling as is known in the art. Defined in the center of the mold plate 16 is a substantially circular aperture or opening 28 which is configured to accommodate a portion of the arm plate 18 as detailed further below.
The arm plate 18 is substantially circular in shape and like the mold plate 16, comprises a corresponding plurality of radial protrusions or spokes 30 emanating from a body 31. Disposed on the distal end of each of the plurality of radial protrusions or spokes 30 is a terminal or receiver 32 which itself comprises a substantially semi-circular or crescent shaped strike aperture 34 defined through the terminal or receiver 32 on at least one lateral edge or side. Coupled to a front or forward facing surface of each of the terminals or receivers 32 is a toggle clamp or other coupling means 36. In the center of the arm plate 18 is a raised or elevated platform or disc 38 which extends upward from the body 31 of the arm plate 18. The platform or disc 38 is substantially circular and is sized and shaped to tightly fit within or be accommodated within the aperture or opening 28 of the mold plate 16 as is discussed in further detail below.
Both the mold plate 16 and the arm plate 18 are preferably comprised of metal or metal alloys which are durable enough to withstand the high temperatures and forces used during the rotational molding process. Additionally, while the aperture or opening 28 of the mold plate 16 and the platform or disc 38 of the arm plate 18 are shown and described as being circular, it is important to note that other shapes may be used without departing from the spirit or scope of the invention. Similarly, the bolts or rods 22 and the corresponding strike apertures 34 are seen as being cylindrical and semi-circular, respectively, however it should be noted that this is for illustrative purposes only. The bolts or rods 22 and the strike aperture 34 may comprise any number of different shapes or configurations, provided that the strike aperture 34 is capable of interacting or engaging with at least one of the bolts or rods 22.
Detail of how the mold plate 16 interacts or engages with the arm plate 18 may be seen in
Once properly placed, the mold plate 16 is rotated with respect to the arm plate 18 so that the radial protrusions or spokes 20 of the mold plate 16 are brought into close proximity to the radial protrusions or spokes 30 of the arm plate 18. The mold plate 16 is continually rotated relative to the arm plate 18 until each of the bolts or rods 22 are firmly inserted or accommodated by a corresponding strike aperture 34 of an adjacent terminal or receiver 32. Each toggle clamp or coupling means 36 is then actuated by disposing a catch or clasp 42 over the cap or head 24 of the bolt or rod 22 then locking it into position using a lever 44 as seen in
How the plate assembly 10 is implemented into a rotational molding apparatus and its associated use may be had by turning to
Next, the mold frame 14 comprising the mold plate 16 is then brought down on top of the arm plate 18 as seen in
Once the platform or disc 38 is inserted within the mold plate 16, the mold plate 16 and the arm plate may be temporarily locked or coupled together. As seen in
To decouple or remove the mold frame 14 and mold plate 16 from the arm plate 18, the lever 44 of each of the toggle clamps or coupling means 36 is actuated by being pulled away from the terminal or receiver 32 which is turn loosens or relaxes the clasp 42. The clasp 42 may then be taken off of the bolt or rod 22 and rotated away. As seen in
With the mold 12 and mold frame 14 removed, a new or different mold and mold frame comprising its own corresponding mold plate 16 may then be coupled to the arm plate 18. Alternatively, after the mold frame 14 has been decoupled from the arm plate 18, the specific mold 12 may be removed from the mold frame 14 and then replaced by a new or different mold. The mold frame 14 comprising the new mold may then be recoupled to the arm plate 18 as detailed above. In this manner, the manufacturer may repeatedly replace or change out molds as needed while still using the same permanent arm plate 18, thereby increasing the efficiency of the overall rotational molding process. Additionally, because the mold frame 14 is removably coupled to the arm plate 18 via a relatively straightforward rotation and locking process, the safety of the workers tasked with operating the rotational molding machine is enhanced as opposed to the current means which require the mold to be bolted or unbolted to the rotational arm every time a mold needs to be replaced.
Great detail of how the mold plate 16 and the arm plate 18 interact or are applied to form a rotational molding assembly 100 may be seen in
Turning to
When the mold 12 needs to be recharged, exchanged, or removed from the rotational molding assembly 100, each of the toggle clamps or coupling means 36 are actuated into an open position and the mold 12 and mold frame 14 comprising the mold plate 16 are rotated with respect to the arm plate 18 coupled to the housing 104 and outer arm 112 as seen in
How the plate assembly 10 may be used in the overall rotational molding process may be seen by turning to
In one embodiment seen in
First, at the load/unload station 204, an initially empty mold 12 is charged or filled with a predetermined type, color, and amount of granulated plastic as dictated by the item to be manufactured by the mold 12. One or more users with the assistance of a small crane or other lifting device then lift the mold 12 and mold frame 14 and couple them to an arm plate 18 disposed on the distal end of one of the cylindrical gears 110 as discussed above, namely by bringing the mold plate 16 coupled to the mold frame 14 into contact with the arm plate 18 and then slightly rotating the mold plate 16 so that the arm plate 18 may first engage and then be locked to the mold plate 16.
With the mold 12 and mold frame 14 firmly and safely secured to the first cylindrical gear 110, the central hub or indexing unit 202 rotates or indexes in a clockwise direction so that the now formed rotational mold assembly 100 is brought into the oven or heating means 206. As the heat from the oven or heating means 206 begins to melt the granulated plastic within the mold 12, the central hub or indexing unit 202 begins to rotate the rotational mold assembly 100 along a primary rotation axis 216 and a secondary rotation axis as seen in
The central hub or indexing unit 202 and the plurality of cylindrical gears 110 are configured to spin or rotate the rotational mold assemblies 100 along their respective primary and secondary axes 216, 218 as discussed above throughout the rotational molding process, however specific periods of one or more axes of rotation may be implemented according to a predetermined program or schedule.
After being sufficiently heated, the central hub or indexing unit 202 rotates again which removes the rotational mold assembly 100 from the oven or heating means 206 and brings it into a first cooler or cooling means 208. The cylindrical gear 110 continues to rotate the rotational mold assembly 100 along one or both of the primary and/or secondary rotation axes 216, 218 while it and the now liquid plastic within begin to cool. Next, the rotational mold assembly 100 is brought into a second cooler or cooling means 210 by the central hub or indexing unit 202 so as to provide further cooling to the rotational mold assembly 100. Meanwhile, each time the central hub or indexing unit 202 rotates the first rotational mold assembly 100 between the oven or heating means 206 and the first cooler or cooling means 208, or between the first cooler or cooling means 208 and the second cooler or cooling means 210, a subsequent rotational mold assembly 100 on a different cylindrical gear 110 is rotated into the oven or heating means 206 or the first cooler or cooling means 208 accordingly.
Finally, the central hub or indexing unit 202 indexes or rotates the rotational mold assembly 100 back to the load/unload station 204 where workers, with the assistance of a crane or other lift device, decouple or remove the mold 12 and mold frame 14 from the cylindrical gear 110 by actuating the toggle clamps or coupling means 36 disposed on the arm plate 18, rotating the mold plate 16 relative to the arm plate 18, and then lifting the mold 12 and mold frame 14 away. Once separated, the molded item may be removed from the mold 12 which then can be refilled or recharged with more granulated plastic so that that rotational molding process may be repeated. Alternatively, the mold 12 and mold frame 14 once removed may be quickly and easily replaced with a new or different mold when a different molded item is to be manufactured.
In an alternative embodiment seen in
As can be seen from the above, every time the central hub or indexing unit 202 rotates each rotational mold assembly 100, a corresponding mold 12 may be removed from the arm plate 18 as discussed above so that the newly molded item may be removed and fresh plastic may then be added to repeat the process. Because operation of the plate assembly 10 is fast, easy, and does not require individuals to remove fixtures such as bolts in order to couple and decouple a mold 12 from the rest of the rotational mold assembly 100, the overall time for production of manufacturing any number of plastic items is reduced without compromising the individual's safety.
Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the embodiments. Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the embodiments as defined by the following embodiments and its various embodiments.
Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the embodiments as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the embodiments includes other combinations of fewer, more or different elements, which are disclosed in above even when not initially claimed in such combinations. A teaching that two elements are combined in a claimed combination is further to be understood as also allowing for a claimed combination in which the two elements are not combined with each other, but may be used alone or combined in other combinations. The excision of any disclosed element of the embodiments is explicitly contemplated as within the scope of the embodiments.
The words used in this specification to describe the various embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification structure, material or acts beyond the scope of the commonly defined meanings.
Thus if an element can be understood in the context of this specification as including more than one meaning, then its use in a claim must be understood as being generic to all possible meanings supported by the specification and by the word itself.
The definitions of the words or elements of the following claims are, therefore, defined in this specification to include not only the combination of elements which are literally set forth, but all equivalent structure, material or acts for performing substantially the same function in substantially the same way to obtain substantially the same result. In this sense it is therefore contemplated that an equivalent substitution of two or more elements may be made for any one of the elements in the claims below or that a single element may be substituted for two or more elements in a claim. Although elements may be described above as acting in certain combinations and even initially claimed as such, it is to be expressly understood that one or more elements from a claimed combination can in some cases be excised from the combination and that the claimed combination may be directed to a subcombination or variation of a subcombination.
Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements.
The claims are thus to be understood to include what is specifically illustrated and described above, what is conceptionally equivalent, what can be obviously substituted and also what essentially incorporates the essential idea of the embodiments.
