EP0956257A1

EP0956257A1 - Unitary, high-load capacity plastic reel

Info

Publication number: EP0956257A1
Application number: EP97944411A
Authority: EP
Inventors: Valentine L. Picton
Original assignee: Enviroreel Plastics LLC
Current assignee: Enviroreel Plastics LLC
Priority date: 1997-09-25
Filing date: 1997-09-25
Publication date: 1999-11-17
Also published as: JP2001504791A; CA2272358A1; WO1999015454A1; IL129894A0; EP0956257A4; AU4591597A

Abstract

A unitary, high-load capacity plastic reel (50) of lightweight design comprises first (55a) and second (55b) substantially circular flanged side portions, a drum portion (60) formed between the flanged side portions, a central shaft hole (75) extending linearly along a central axis of the reel between each flange portion, and a plurality of holes (80) extending from each flange portion to partially within the drum portion parallel to the central shaft hole, the plurality of holes contributing to the lightweight design. A unitary reel forming mold (100) for manufacturing the unitary reel consists of a gate opening (110) enabling a plastics extrusion device to fill the mold. A centrally located mold-pin (229) of tapered design is provided in the mold having an upper surface proximate the gate opening to facilitate even distribution of the plastics from the extrusion device to all parts within the mold.

Description

UNITARY, HIGH-LOAD CAPACITY PLASTIC REEL

FIELD OF THE INVENTION

The present invention relates generally to high load capacity plastic reels and more specifically, to a high load capacity plastic reel of unitary design and a method for manufacturing the same.

BACKGROUND OF THE INVENTION

Many industries employ the use of large plastic reels for winding, storing and dispensing of industrial cables or wires, whether insulated or not, with all of the reels being of multi piece or "modular" design. For example, my prior U.S. Patent No. 5,605,305, the contents and disclosure of which is incorporated by reference herein, discloses a high load capacity plastic cable reel of modular design wherein the drum and side flanges are manufactured separately and then assembled to achieve the reel.

The prior art high capacity cable reels of modular design have several drawbacks. First of all, most of the prior art modular designs requires intricate assembly and a multitude of operations to construct. One such design, for instance, requires injection molding of two side flanges with the center drum being extruded and cut. Then, after molding, the flange portions of the reel must be attached to the drum portion, usually by ultrasonic welding and/or by means of steel bolts. Often, the nuts and bolts become loosened which can result in unbalanced reels. Thus, a balancing of these reels, and/or the tightening of the bolts is necessary to ensure proper cable/wire winding operations, especially when winding at speeds of up to 7,000 feet/minute. In another type of modular construction, reels may be made of two inj ection molded parts, each comprising of a flange portion and a one-half drum portion, with the two parts being bolted together with steel bolts and plastic interlocks. In most cases, the interlocks are found between the two ^lA drum portions to prevent separate spinning of one Yi drum portion from the other. This separate rotating at and between the ∑ drum portions interfere with the winding process. The plastic interlocks themselves often break and separate rotation of the two parts occurs. Unfortunately, it is difficult to detect when the interlocks are broken since they are in the inside of the reel and not easily visible.

Another drawback is that prior art modular reels are inherently weaker as they contain weak points and stress points and are subject to breakage. The ultrasonic weld points mentioned above are but one example. Additionally, the flange portions are subject to bowing out and essentially, are not strong enough to withstand certain phases of the wire production process.

Also, most prior art plastic reels of modular design may not withstand a few foot drop from a forklift. Oftentimes, the forklift itself will break the plastic flanges themselves when they are hit by the fork. Furthermore, winding of wire or cable onto modular plastic reels cause many interruptions in the wire production process if they bend or break during the process which is a frequent occurrence and customers will reject the reels of wire if they are bent, misshapen or broken. If reels need tightening, the wire production line will have to be interrupted and this is a major problem faced by wire manufacturers. Manufacturers of steel reels now provide the service of repairing the multi piece reels that have become misshapen or broken, which, is a big business. The broken plastic reels are usually scrapped and end up in a landfill. There exist prior art modular reels comprised of steel for the limited use of winding wire, e.g., copper or aluminum, that is hot from the wire extrusion process at typical temperatures of 150° F. The steel reels are typically heavy, at least 120 lbs. or more, are easily deformable, and, when out of balance, cause a lot of vibration during winding operations. They require constant balancing. Even if the bending is almost imperceptible, it may still cause dislocations in the production process resulting in the unwinding of wires in an inconsistent manner and even wire breakage. This will cause the production line to shut down and the scrapping of some materials. Additionally, steel reels are rarely used for shipping since they are too heavy and costly.

There do exist plastic reels of unitary design, but these plastic reels are extremely small and lightweight, and are for carrying lightweight thread or small amounts of coated wire, i.e., they do not have the capacity (in terms of both size and weight bearing capacity) to carry heavy wire and cable. These plastic reels are typically manufactured by extrusion processes, and may

require intricate secondary processes in their production, such as macliimng.

Use of extrusion techniques would be very difficult for large intermediate and high-load capacity unitary reels because the thickness of the material and the strength required of the reels make extrusion difficult. Furthermore, the amount of machining necessary for the large size unitary reels contemplated would be prohibitive.

It would thus be highly desirable to provide intermediate and high-load capacity reels of unitary design that are lightweight, and extremely durable. It would furthermore be highly desirable to provide intermediate and high-load capacity reels of unitary design that can be manufactured quickly and efficiently with nrinimum post-molding machining operations.

SUMMARY OF THE INVENTION The instant invention is a plastic reel of unitary design having first and second flange portions and a drum portion formed linearly therebetween. The unitary reel is of size and shape for handling intermediate and high-capacity loads and includes a central shaft hole extending linearly along a central axis of the reel and, additionally, is provided with a plurality of air holes extending partially within the drum portion parallel to the central shaft hole for - 4 - decreasing the weight of the reel. The strength of the unitary reel is not compromised, however, and the lightweight unitary reels are of high-load capacity ranging from 50 lbs. up to 2000 lbs. depending upon the diameter of the drum and flange portions. This is due to the fact that in such a unitary design, stress points commonly found in multi piece reels, are virtually eliminated.

For the molding process, a closed system approach is implemented. Particularly, a four piece mold is provided to form a complete reel forming cavity with one piece of the mold including an opening or gate to allow molten plastic to flow from an extrusion device within the mold cavity. The central shaft opening and plurality of weight decreasing pockets are formed during the molding process, with the central shaft opening requiring a short secondary machining operation to complete the hole. The process for forming the unitary, high load capacity reel is thus quick and efficient.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRD F DESCRIPTION OF DRAWINGS Figure 1 is a perspective view of the unitary, high-load capacity reel of the invention.

Figure 2(a) illustrates the top mold portion for the reel mold and Figure 2(b) is a cross- sectional view of the top mold portion taken along line AA in Figure 2(a).

Figure 3(a) illustrates the bottom mold portion for the reel mold and Figure 3(b) is a „„„,_« . O 99/15454

- 5 - cross-sectional view of the bottom mold portion taken along line BB in Figure 3(a).

Figure 4(a) illustrates the central side mold portions for the reel mold and Figure 4(b) is a cross-sectional view of the central side mold portions taken along line CC in Figure 4(a). Figure 5 is the cross-sectional view of the completed mold prior to filling. Figure 6 illustrates a completely filled reel cavity.

Figure 7 is the cross-sectional view of the completed unitary reel.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 illustrates a perspective view of the high-load capacity reel 50 (hereinafter "reel") of unitary design. As referred to herein, a high-load capacity reel includes reels capable of accommodating intermediate loads, e.g., in the range from about 50 lbs. to 1000 lbs., however, greater loads can be accommodated.

As shown in Figure 1, the reel 50 includes two flange portions 55a and 55b and central drum portion 60 and is dimensioned to carry and dispense heavy loads of cables, wires or like materials. Diameters of each of the flange portions 55a,b may range from 16" to 32" or greater, and the diameter of drum portion 60 ranges between 12" to 22" or greater, according to the particular application and customer needs. Accordingly, the weight and load bearing capacity of the unitary reel will vary. For the 16" diameter reel weighing approximately 30 lbs., it is estimated that load capacities range between 50-100 lbs. For the 22" diameter reel weighing approximately 50 lbs. , it is estimated that load capacities range between 100-500 lbs.

For the 30" diameter reel weighing approximately 100 lbs., it is estimated that load capacities range between 250-1000 lbs. The thickness of each flange portion 55a,b will also vary in accordance with the customers requirements, and can range anywhere between one and several inches thick. Accordingly, the above reel weights and load range estimates will vary with the flange thicknesses.

As further shown in Figure 1, the reel includes a first central shaft hole portion 75 extending centrally through each of the flange portions 55a,b and drum portion 60 for accommodating placement of the reel on a mandrel or winding shaft of a cable/wire dispensing or winding machine to aid in the winding and/or dispensing of the cable or wire materials. As

will be explained, most of the central shaft hole 75 is molded during the molding operation, but

a small part of the hole is finished off by machining in a secondary operation. Surrounding the

central shaft hole portion 75 are a plurality of hollow pockets or holes 80 that are also formed during the molding process and extend from each of the flange portions 55a,b to within the drum portion 60 of the reel parallel to the central shaft hole. These holes 80 are provided for

decreasing the weight of the reel and consequently, the load bearing capacity of the reel. As shown in Fig. 1, eight (8) holes are provided, however, more or less can be provided depending upon the desired load bearing capacity. The diameters of the holes may vary depending upon the desired load capacity and need of the customer. According to the principles of the invention, these holes are provided during the formation of the unitary reel, and not as a subsequent machining operation.

As known to skilled artisans, one or more drive holes 90, shown in Fig. 1, can additionally be machined or molded to enable attachment to a customer's winding/dispensing machine for reel rotation during the cable/wire winding or dispensing operation. Although not shown, additional starter cable holes may be molded or machined at the edge of the drum where it meets the flange for attaching wire/cables in the winding process.

The process for manufacturing the unitary, high-load capacity reel of the invention requires the introduction of molten plastic into a mold 100 described hereinbelow with respect to Figs. 2(a) - 6. Molten plastic is provided by an extrusion device (not shown). The types of molten plastics used for forming the unitary reel include any of the conventional commodity thermoplastic resins and engineering resins, including polyethylene, polypropylene, polystyrenic resins, polyester resins, PVC's, polycarbonates, etc., with or without color concentrate additives for color, foaming agents for lightening, and other additives for increasing flexibility, longevity, rigidity, and/or strength. When certain high density polyethylene plastic or other heat resistant materials are used, the formed unitary plastic reel

can be used for hot-wire winding operations. Furthermore, the inventive reel may be made out of reprocessed and/or recycled (post industrial and/or post consumer) resins. In the

preferred embodiment, the output of the extrusion device (not shown) is introduced through a gate 110 provided within the body, e.g., top mold portion 210, of the mold 100 for pouring

molten plastic, under pressure, into the mold 100 (Fig. 5). In one example, the gate opening

may range between 2" inches to 4" inches in diameter, however this may be expanded, as necessary, e.g., for filling larger molds producing larger reel diameters.

As illustrated in Figures 2(a) - 5, the mold 100 is a four piece mold having a top mold portion 210, a bottom mold portion 220, a first central portion 230, and a second central portion 240 forming a mold cavity 150 when connected together by suitable means such as pins

or bolts 99a, .. ,99b. The diameter of the opening 110 is such to accommodate a tight-fit with the extrusion device 135 so that the molten plastic throughput from the extrusion device is great enough to fill the mold cavity 150, which is a closed system, in a minimum amount of time. It should be understood that the size of the extrusion device providing the molten plastic and the specifications thereof, will depend in large part upon the size and weight of the unitary reel.

Figure 2(a) illustrates a view taken underneath of the top mold portion 210 and Fig.

2(b) is a cross-sectional view of the top mold portion 210 taken along line AA of Fig. 2(a). Top mold portion 210 is dimensioned as a square slab of aluminum or steel, approximately 1"

to 2" (inches) thick and provided with a centrally-located opening 215 for attachment with the extrusion device 135. As shown in Figs. 2(a) and 2(b), the under surface 211 of top mold portion additionally contains a circular lip or flanged portion 212 for outlining one flange portion, e.g., flange 55b, of the formed unitary reel 90 (Figure 1). It is understood that the circumferential lip portion may be formed integrally with the underside of the top mold portion or, may be a separate piece bolted thereto, and, preferably, is of a height approximately equal to the desired thickness of the flange portion of the reel, e.g., 2" inches. As shown in the top

view of top mold portion 210, in Figure 2(a), there is additionally provided several bolt receiving openings 208 for receiving bolts that attach steel pins 218a, 218b (as shown in Fig. 2(b)) to the underside of the top mold portion within the circular lip region that protrude down within the cavity of the mold. As will be explained, during the reel forming process, the molten plastic flows around the steel pins within the mold and harden around the pins resulting in the formation of hollowed pockets extending from within the drum portion to the flange portion of the formed reel resulting in a reel of decreased weight. A plurality of bolt receiving holes, e.g., 204a,..,d are provided for securely attaching the top mold portion with the first and second central mold portions.

Figure 3(a) illustrates a top view of bottom mold portion 210 and Fig. 3(b) is a cross- sectional view of the bottom mold portion 220 taken along line BB of Fig. 3(a). As shown in

Figures 3(a) and 3(b), the bottom mold portion 220 is a slab 221 constructed similarly as the top mold portion 210 and is preferably of similar thickness. As in the top mold portion, the bottom mold portion is provided with a circular flange or lip portion 222 that extends upward when the mold is laid horizontal and, as in the case of the circular lip of the top mold portion, is of a height approximately equal to the desired thickness of the other flange portion of the formed reel. Additionally provided in the bottom mold portion are a plurality of bolt receiving openings 223

for securely attaching a plurality of steel or aluminum pins 228a, 228b (shown in Fig. 3(b)) that protrude within the cavity 150 as shown in Figure 5 resulting in the formation of like air pockets within the drum portion of the formed reel as the pins 218a,b provide in the top mold portion.

A single bolt receiving opening 225 is provided centrally within the circular lip region of the bottom mold for securely attaching a larger solid steel or aluminum pin member 229 that protrudes within the drum portion of the mold proximate the top mold portion. This large solid pin member 229 functions to form the majority of the central shaft bore 75 of the resultant reel.

As will be explained, the remaining portion of the shaft hole is simply machined. Referring back to Fig. 3(a), a plurality of bolt receiving holes, e.g., 224a,..,d are provided for securely attaching the bottom mold portion with the first and second central mold portions. It should be understood that the provision of four bolt receiving holes 204a,..,d in the top mold portion and holes 224a,..,d in the bottom mold portion are for illustrative purposes and, according to design considerations, the amount of the bolts required to secure the top and bottom mold portions to the central side portions can be fewer or greater in number. It should be understood that other additional means

such as clamping or pressure may be used to secure the mold portions together.

Figure 4(a) illustrates a top view of the central mold portions 230 and 240 shown connected together as part of mold 100. As shown in Figure 4(a), each central mold portion 230,240 provides a half a cylindrical opening 231,241, respectively, such that when connected, form the drum portion of the unitary reel. Figure 4(b) illustrates a cross-sectional view of the two central mold pieces taken along line CC of Figure 4(a). The first central mold portion contains at least one bolt receiving hole 207a for receiving the bolts 99a for connecting the top mold portion 210 and, likewise contains bolt receiving hole (not shown) for connecting the bottom mold portion 220. It should be understood that other types of clamping, bolting, or pressure mechanisms may be used. Similarly, as shown in Figure 4(a), the second central mold portion 240 is provided with bolt receiving hole 207b for receiving the bolts 99b for connecting the top mold portion 210 and, likewise contains bolt receiving hole (not shown) for connecting

the bottom mold portion 220. As known to skilled artisans, molded plastic will shrink upon cooling, so the dimensions of the mold portions 210,220,230 and 240 may be slightly expanded to ensure proper dimensions of the formed reel. For instance, the circumferential lip of the top mold for forming the 16" diameter flange portion may be 17" inches in diameter, by way of illustration.

Figure 5 illustrates the preferred embodiment of the fully assembled unitary reel mold 100 showing the upper set of pins 218a,b attached to the top mold portion 210 depending downwards within the mold cavity 150, the bottom set of pins 228a,b attached to the bottom mold portion 220 protruding upward to within the mold cavity 150, and the large solid central

pin member 229 attached to the bottom mold portion 220 protruding upward in axial alignment with the top opening 110 of the top mold portion 210 of the reel mold, and preferably, to the extent that the top surface 221 of the pin 229 is disposed directly below the opening 110. In one embodiment, the distance between the top surface of the pin and the mold opening is between 3/8" and 5/8" inches however, this may vary. Besides contributing to the light-weightedness of the resulting formed unitary reel, the central pin 229 enables the formation of the central shaft opening for the reel. The central pin also provides a diverting function for distributing molten

plastic flow from the opening or gate 110 of the top mold portion 210 to all sides of the mold cavity. Preferably, the central pin 229 is tapered in design having a flat top surface diameter slightly less, e.g., between 1/8" inch - 3/8" inches less, than the diameter of the gate 110 under which it is disposed, and a larger bottom pin diameter ranging between 3" - 5". Thus, the central

pin is tapered at an angle of approximately 2.0 - 4.5° enabling even displacement of molten

plastic flow from the extrusion device through the gate and around the central pin enabling complete and even fill to within all portions of the mold, and additionally, aiding in the removal

of the formed reel from the mold. Each pin of the upper and lower sets of air-pocket forming pins range approximately from 6" to 12" (inches) in length and 2" to 6" (inches) in diameter, but

preferably, are tapered in design. It should be understood that decreased pin sizes, e.g., length

and diameter, of all the pins will decrease weight and accordingly decrease cycle times as less materials will be required.

In the preferred embodiment, the molten plastic is output from the extrusion device at a pressure of approximately 5000 lbs/sq. inches (in²) such that the entire mold is filled in a short period of time, i.e, between 2 - 5 minutes, depending upon the size of the reel. The force alone of the extrusion device rotating screw (not shown) enables the molten plastic to fill the mold. The extrusion device automatically shuts itself off after a certain predetermined number of screw revolutions depending upon 1) the size of the reel to be formed, 2) the gate, and 3) the pressure of the molten plastic output of the extrusion device. A "topping off

operation is then performed at a lower pressure, e.g., approximately 4000 lbs/sq. inches, to enable complete mold filling. It should be understood that me means of filling of the mold may vary as well and may include injection of the molten material by an injection device as in or similar to injection molding or structural foam molding.

Figure 6 illustrates the mold 100 having a completely filled mold cavity 150. As Preferably, as shown in Figure 6, a small fill conduit or tunnel 80 is provided in the mold so that an operator can manually check the fill with a probe to make sure that each part is

completely packed out.

After complete fill, the mold 100 is immediately placed and completely submerged in a cooling bath of, e.g., water, as a cooling bath is an efficient way of cooling down such a large part. In the preferred embodiment, the temperature of the cooling bath is about 40° F but the cooling bath is not limited to this temperature and may vary.. In another embodiment,

both internal and external cooling of the unitary reel may be provided, e.g. , by means such as liquid cooling jackets formed around the mold pieces and having liquid coolant circulation conduits within each of the pins to facilitate cooling and decrease cooling time, or, by means of jet spray of cold water against the mold.

After cooling for approximately 5 to 30 minutes or more, which time will depend upon the size and/or weight of the reel, the top, bottom and then side portions of the mold 100 are unbolted and the formed reel is removed for final cooling and shrinkage. It should be understood that the opening and closing of the molds may be simplified and/or more automated by constructing automatic "debolters" as an external device, or by holding the mold parts together by a clamp, or by pressure in an injection molding or similar machine. Subsequent to an approximate 24 hour period for shrinkage and further cooling, the formed reel is machined to complete the central shaft hole, and, further for smoothness, e.g., to complete and round out tops of holes, etc.

Figure 7 illustrates a cross-sectional view of the formed unitary reel of the invention when removed from the mold 100. As shown in Figure 7, the small air pockets or holes 80 do not have to be machined and, as mentioned above, increasing pin size will decrease the weight of the reel without necessarily compromising strength depending upon the capacity needs. The central shaft hole is not completely hollowed and a small portion 85 of the reel has to be machined in a secondary operation to complete the central shaft hole 75. Preferably, the central shaft hole is tapered and it is desirable that the secondary machining operation forms the central shaft hole 75 in accordance with the shaft dimensions or mandrel of the winding

machine. Preferably the shaft hole 75 is dimensioned to enable cable/wire winding in most

winding machines. The process described is ideally suited with large and heavy parts which require a closed system mold such as a high load capacity reel. Any more sophisticated processes are perhaps too expensive relative to the method of the invention due to cooling time, and cost of molds and machines. However, such molding methods such as injection molding, low pressure structural foam molding, gas assisted injection molding and compression molding may be used in accordance with the principles described herein.

The foregoing merely illustrates the principles of the present invention. Those skilled in the art will be able to devise various modifications, which although not explicitly described or shown herein, embody the principles of the invention and are thus within its spirit and scope.

Claims

WHAT IS CLAIMED IS:

1. A unitary, high-load capacity plastic reel of lightweight design comprising: first and second substantially circular flanged side portions; a drum portion formed between said flanged side portions; a central shaft hole extending linearly along a central axis of the reel between each

flange portion; and, a plurality of holes extending from each flange portion to partially within the drum portion parallel to the central shaft hole, said plurality of holes contributing to said lightweight

design.

2. A unitary, high-load capacity plastic reel as claimed in Claim 1, wherein said plurality of holes includes a first set of holes extending from the first flange portion to within the drum portion, and a second set of holes extending from me second flange portion to within the drum portion in one-to-one correspondence with said first set of holes.

3. A unitary, high-load capacity plastic reel as claimed in Claim 1, wherein said central shaft hole is of tapered design and subject to a secondary machining operation.

4. A unitary, high-load capacity plastic reel as claimed in Claim 2, wherein said first and

second sets of holes are distributed substantially symmetrically.

5. A unitary, high-load capacity plastic reel as claimed in Claim 1 capable of

accommodating up to 2000 lbs. of load, said load comprising wire or cable.

6. A mold for manufacturing a unitary, high-load capacity plastic reel of lightweight

design comprising: top mold portion for forming a first side flange of said reel, a central side mold portion for forming a drum portion of said reel, and bottom mold portion for fo╧Çning a second side flange for said reel, said top, central side and bottom mold portions forming a mold cavity,

said top mold portion having a first plurality of pins extending from an inner surface thereof to partially within the mold cavity, and said bottom mold portion having a second plurality of pins extending from an inner surface thereof to partially within the mold cavity and a central pin extending substantially centrally from the inner surface to the top mold portion, said top mold containing an opening for receiving molten plastics, said central pin capable of diverting molten plastic entering though said opening to enable even distribution of molten plastics within the mold cavity.

7. A mold for manufacturing a unitary, high-load capacity plastic reel as claimed in Claim 6, wherein said first and second plurality of pins are substantially perpendicular to each of the respective top and bottom mold portions.

8. A mold for manufacturing a unitary, high-load capacity plastic reel as claimed in Claim 6, wherein said first and second plurality of pins are in one-to-one correspondence.

9. A mold for manufacturing a unitary, high-load capacity plastic reel as claimed in Claim 6, wherein said first and second plurality of pins are distributed substantially symmetrically.

10. A mold for manufacturing a unitary, high-load capacity plastic reel as claimed in Claim 6, wherein each of said first and second plurality of pins are tapered.