BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood from the following description, with reference to the attached drawings, which illustrate exemplary embodiments for carrying out the invention, and in which:
FIG. 1 is a perspective view of a prior pin spotter bin made largely from sheet steel and associated parts;
FIG. 2 is a perspective view of a first embodiment of a storage bin according to the invention, assembled to a support frame;
FIG. 3 illustrates, in perspective, a comparison between a portion of the prior bin of FIG. 1 and a portion of the bin of FIG. 2 according to the invention;
FIG. 4 is a perspective view of a second embodiment of a storage bin according to the invention, assembled to a support frame;
FIGS. 4
a and 4b schematically illustrate two stages of a thermoforming process that can be used to manufacture the second embodiment;
FIG. 4
c schematically illustrates a part made by the process of FIGS. 4a, 4b;
FIG. 5 is a cross-sectional perspective view of the second embodiment, taken through the cavities of the first and fifth pins;
FIG. 6 illustrates top views of localized portions of the 10-pin areas of the first and second embodiments of the storage bins according to the invention;
FIG. 7 illustrates the bins of the first and second embodiments, with particular reference to structures facilitating horizontal stiffness;
FIG. 8 illustrates a support frame for the storage bins of the first and second embodiments of the invention;
FIG. 9 illustrates respective portions of the storage bins of the first and second embodiments of the invention, with exploded showings of the mounting hardware; and
FIG. 10 illustrates the storage bin of the second embodiment with indexing and time stamp features.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 illustrates a storage bin 13 for a bowling pin spotting apparatus according to a first embodiment of the invention. The bin 13 is mounted to a frame that includes channels 14, 15 made of light tubular steel, for example.
The bin 13 is to be used in conjunction with a shuttle assembly for retaining pins in. and releasing pins from, the ten cavities 16a-16j of the bin to the spotting/respotting table, such as the shuttle linkage assembly disclosed in U.S. Pat. No. 5,439,418, the disclosure of which is hereby incorporated by reference thereto for this purpose. In fact, the bin 13 could be substituted for the pin storage device 2 of U.S. Pat. No. 5,439,418 in a bowling pin spotting apparatus.
As can be seen, the bin 13 is not formed as a hollow structure in the manner of the bin of the aforementioned U.S. Pat. No. 5,439,418 and U.S. Design Pat. No. 366,510. In fact, because bin 13 is not hollow, it could not be made by means of a rotational mold. Instead, bin 13 is made by thermoforming. In addition, in a particular embodiment of the invention, the bin made from a high-density polyethylene (HOPE), rather than from the LOPE disclosed in U.S. Pat. No. 5,439,418, processed into sheets for manufacture by thermoforming.
During a period of investigation and impact testing, it has been determined that, rather than using a LDPE and relying upon a rotomolding process to make a one-piece plastic bin, as disclosed by U.S. Pat. No. 5,439,418, a different material and a different manufacturing process could be implemented to advance the technology currently used in bowling pinspotting apparatuses. More specifically, it was determined that the bin 13 could be made from a high-density polyethylene (HDPE), processed into sheets, such as by extrusion, and used in a thermoforming process. It should be recognized that other materials are also contemplated by the present invention such as, for example, other plastics including other polyethylene type of materials, and even more specifically, ThermoPlastic Olefin (TPO), and more particularly HDPE manufactured by PrimeX Plastic Corporation. The HDPE or other materials contemplated by the invention provide high impact for the bowling pinspotting apparatus. Hereinafter, the present invention is discussed mainly with reference to HDPE; although the other high impact materials discussed herein work equally well with the invention.
Thermoforming has a special cross-linking property that rotomolding, which relies upon the heating and melting of a polymer powder, does not. Specifically, cross-linking is introduced into the HOPE material when the material is extruded and rolled into sheet form, for subsequent use in thermoforming, which causes the long polymer molecule chains to bind together at various intersections along their lengths. Interweaving and cross-linking of the polymer chains yield a plastic material that is very strong, flexible and, most importantly for the particular subject matter of the invention, increased impact resistance. In a particular embodiment, the extruded sheet used in manufacturing the bin 13 has a thickness of 5/16 inch, although that particular thickness is not intended to limit the invention.
Thermoforming is a method of manufacturing plastic parts by preheating a flat sheet of plastic, such as an aforementioned extruded sheet of HDPE, the edges of which are damped in a frame, then bringing the sheet into contact with a single-surface temperature-controlled mold whose shape it takes. The mold can be typically made of cast or machined aluminum, due to the relatively high coefficient of thermal conductivity of aluminum, which allows for consistent cooling cycle times through a production run, although other materials can be used, particularly if low volume productions are contemplated. Once cooled, the formed sheet is removed from the mold and trimmed as necessary.
Thermoforming broadly relates to any process of forming a sheet of plastic, typically a thermoplastic sheet, which comprises heating the sheet until it become pliable and forcing it onto or into a surface mold. Tooling used in thermoforming is referred to as either male or female. If a male mold is used, the sheet is forced onto the mold; if a female mold is used, the sheet is forced into the mold. Typically, the forcing of the sheet into or onto the surface mold is accomplished with a vacuum, although air pressure and direct mechanical force can be used, including combinations of such forces.
The thermoforming process used to produce bin 13 of FIG. 2 is made using a male mold (not shown). That is, the heated sheet of extruded plastic (such as HDPE) is draped over the projecting surfaces of the male mold, such as projections shaped for the purpose of forming the oblong cavities 16a-16j of the bin 13. The details of the surfaces of the bin 13 of FIG. 2, including the relatively complex shapes of the cavities, are largely based upon the assembled geometries of the metal bin 1 of FIG. 1. For example, as shown in FIG. 3, the pin guiding surfaces 17 of the bin 13 of the first embodiment of the invention are designed to replicate, in form and function, the pin guides 3 of the prior bin 1. Similarly, the end surfaces 18 of the bin 13 of the first embodiment of the invention are designed to replicate, in form and function, the pin butt guides 9 of the prior bin 1. Further, the top surfaces 19 of the bin 13 of the first embodiment of the invention are designed to replicate the top surfaces of the spacers 6 of the prior bin 1. In addition, the shoulders 20 of the bin 13 of the first embodiment of the invention are designed to replicate the pin assembly brackets 4 of the prior bin 1. Other similarities can also be observed.
As with the bin of U.S. Pat. No. 5,439,418, each of the cavities 16a-16j of bin 13 defines a minimum cross sectional area, i.e., an opening having the general shape of a bowling pin taken along its longitudinal axis but having a width slightly larger than the width of a conventional bowling pin. As shown, for example, in FIG. 3, each of the cavities 16a-16j includes a shoulder 20 at its forward portion, i.e., the portion which corresponds to the head of a bowling pin. Each of the cavities 16a-16j is also shorter than the length of a conventional bowling pin and the cavities are constructed and arranged to bias the base of a bowling pin in a forward direction so that the head of the pin rests on the shoulder 20 in the forward part of a cavity 16 and the base of the pin is supported from below by movable support members of the shuttle assembly (not shown) when the pins are stored in the bin 13 in a first supported, or stored, position.
When pins are to be released from the bin 13, by means of the reciprocation of the support members of the shuttle assembly from beneath the pins, the pins pivot downward base-first through their respective cavities as opposite surfaces 17 (see FIG. 3) of the cavities support and guide the upper portion of the base of each pin in their pivoting and downward release from their respective cavities.
The geometry of the bin 13 of the first embodiment of the invention differs from that of U.S. Pat. No. 5,439,418 and U.S. Design Pat. No. 366,510. A first difference relates to the geometry of the cavities 16a-16j. In US '418 and USD '510, the cavities are relatively widely scalloped along their interior surfaces from the upper surface of the bin down to the through opening of each cavity. This geometry has been found to allow the pins to bounce around as they are delivered by the distributor, rather than to settle into the various cavities 16a-16j relatively quickly. By contrast, as can be seen in FIGS. 2 and 3, the interior surfaces of the cavities are more steeply inclined, which allow the pins to bounce around less and to become more firmly engaged in the respective cavities as the pins are delivered by the distributor. For example, the interior surfaces of the cavities in the area of the head of the pin and the base of the pin provide for a closer fit between the cavities and the pins.
In addition, the geometry of the bins of US '418 and USD '510 includes a relatively flat upper surface surrounding the pin cavities, whereas the bin of the invention includes a number of functional projections extend upwardly from the area surrounding the cavities, which also facilitate the settling of the distributed pins within the various cavities.
The utilization of the process of thermoforming for the manufacture of a bowling pin storage bin, particularly with its unique geometry, has been found to present challenging issues to be overcome, such as potential part defects such as webbing, surface blemishes, thin material areas at key impact areas, and warping. As recognized by those skilled in the art of thermoforming, as a heated pliable sheet of plastic brought down to be formed over the male cavity, or vice versa, the top surface of the part is controlled by the mold. That is, the area of the mold that contacts the plastic first tends to be the thickest, while the remainder of the plastic sheet is drawn and thins as the sheet is brought further down upon the mold. Using a thermoforming technique, sometimes referred to as drape forming, using a male mold, seemed logical because of the complexity of the pocket geometry, i.e., the complex shapes of the cavities 16a-16j. But, while the top surface is controlled by the mold and tends to be the thickest, with this technique the top surface forms the bottom of the bin and the top of the bin, which is used for mounting the bin, is created by the uncontrolled surface.
Another challenge that is confronted when thermoforming a bin of the invention is that of forming key edges of internal cup shapes. With thermoforming as the plastic sheet is moved onto or into the irregularities of the mold, such as forming the plastic sheet around corners, there is a tendency for the plastic to form relatively large radii which, when compared to the prior art sheet metal bin, such as that shown in FIG. 1, can considerably change the ability of the shapes thus formed to function in the manner intended. The result can disadvantageously affect the ability of the bin to consistently catch and hold the incoming pins. Also, because the bin must function as a two-layer pin storage unit, the ability to catch and hold a second layer of pins can be exacerbated by the aforementioned tendency to form large radii in the internal geometry of the pin cavities.
Still further, because of unique application of thermoforming techniques to the manufacture of a bowling pin storage bin, which is a large part Which includes ten relatively complex and deep pockets, one is challenged to ensure that the horizontal stiffness of the finished product is adequate. This consideration is of importance, for example, particularly when considering the use to which the bin is put, such as, e.g., if a person were to support their weight by leaning out over the bin to grab an orphaned pin.
In addition, unlike prior art sheet metal bins, which can be relatively precisely and firmly mounted to the supporting frame, a plastic bin produces additionally challenges. For example, rubber grommets can be used at least fastening locating to allow the bin to expand and contract thermally with temperature change, to help soften impact noise, and to silence any rattle of large free floating washers, e.g., used to retain the bin at locations where shoulder screws are used, Inherent in thermoforming HDPE, or other plastic, is the inability to accurately trim and machine the mounting holes, Because of this, mounting holes can be replaced with slots to ease any hole alignment issues.
FIG. 4 illustrates a second embodiment of a storage bin according to the invention. In addition to variations in the geometry of the bin of this embodiment, compared to that of FIG. 2, this embodiment is preferably formed using female tooling in the thermoforming process. In contrast to utilizing male tooling, i.e., a male cavity or mold, the heated pliable polymer sheet is bought into engagement with the mold to assume the shapes of the recesses therein. FIGS. 4a and 4b schematically illustrate two stages of a thermoforming process using a female mold and relying upon a vacuum assist in positioning the polymer sheet. In FIG. 4a, after the application of suitable heating, schematically shown as radiating from above, to render the extruded sheet pliable, while clamped in a frame, the extruded sheet is brought to engage the female mold. As can be seen in FIG. 4a, the top surfaces of the mold are the first surfaces to come into engagement with the sheet. As the vacuum continues to be applied through the mold, shown in FIG. 4b, atmospheric pressure pushes the pliable sheet into the recess of the female mold, stretching the sheet to lie against the inner surfaces of the mold. After cooling and removal of the clamped frame, FIG. 4c shows the part that has been formed. FIG. 4c schematically illustrates the tendency of those areas of the sheet which are the last to engage the mold are the thinnest, i.e., the areas which had been stretched during the application of vacuum to the pliable sheet. The thickest areas of the part are those which first engaged the mold, particularly the top of the part.
Returning to the second embodiment of the storage bin of the invention, FIG. 5 illustrates, in perspective view, a longitudinal cross section of the bin. Because the bin of FIG. 5 is produced with a thermoforming process like that of FIGS. 4a, 4b, the top surfaces 21 of the bin are those that are “uncontrolled,” i.e., surfaces that had not been in direct engagement with surfaces of the mold, whereas the undersurfaces 22 of the bin are those that are “controlled,” i.e., surfaces that are formed by being in direct engagement with the surfaces of the mold. In addition, unlike the bin of the first embodiment shown in FIG. 2, the uppermost areas 23 of the bin are those which, during manufacture according to a process like that of FIGS. 4a, 4b, are areas of the pliable sheet that had engaged the surfaces of the female mold first and, therefore, they are the thicker areas of the bin, whereas the bottom areas of the bin of FIG. 5 are those that had engaged surfaces of the female mold later in the process and, therefore, they are the thinner areas, but for which impact resistance is not as much of a factor. Although the surfaces of the bottom areas include those which are contacted by the distributed pins, the impact forces are typically not as significant as those that are absorbed the surfaces of the uppermost areas 23.
FIG. 6 shows top views of localized portions of the 10-pin areas of the first embodiment (portion 1) and the second embodiment (portion 11) of the storage bins according to the invention. Because the bins are essentially symmetrical on either side of a vertical longitudinal median plane through the one and five pins, the portions of the bins shown in FIG. 6 also are representative of the 7-pin areas. The rear wall 25 of the embodiment I is a double drafted backstop wall at 12 degrees to the vertical. Although the pins that are delivered to the bin by the distributor rebound within, the pockets for the seven and ten pins, following initial impact with the bin, fall and settle within the pockets, this somewhat flat, angled backstop can occasionally cause pins to rebound up and out rather than down and in. The double drafted backstop wall 26 of the embodiment II creates a more horizontal impact surface.
FIG. 6 also shows that the pin receptacle geometry of the pockets of embodiment II includes more vertical internal shoulders 27 to catch and hold the pins on rebound compared to those of embodiment I, such as the more angled surfaces such as surfaces 27′ of embodiment II. Further, the pockets of embodiment II are more “pin-shaped” than those of embodiment I. That is, particularly for the pockets for the 7-pin and the 10-pin, the outside wails 28 for engagement with the body of a pin more closely follow the contour of pin, compared to the outside wails 29 of the pockets of embodiment I.
Still further, the embodiment II includes a scalloped entrance edge 30, shown in both FIGS. 5 and 6, which facilitate entry of the pins particularly into the pockets for the seven and ten pins. In addition, a terraced section 31, again particularly for the pockets for the seven and ten pins, help to trap and hold the second layer pin. That is, as mentioned above, the bins of both embodiment I and embodiment II (FIGS. 2 and 4, respectively), are constructed and arranged to hold two layers of pins, i.e., second pin lying upon a first pin, so that the bin can readily supply a pin to the pin table below the bin when needed.
FIG. 7 illustrates the bins of the first and second embodiments, with particular reference to structures facilitating horizontal stiffness. Structural shapes of embodiment II include those that aid in longitudinal support of the bin, which also facilitate the thermoforming process. For example, the somewhat abrupt backstop bosses 32 of embodiment I are not a feature of embodiment II, the pockets of embodiment II instead having a smoother perimeter that particularly improves the catch and hold of second layer pins. In addition, the side edges 33 of the bin of embodiment II are vertically flanged, whereas those of the bin of embodiment I are not.
Also for the purpose of increasing stiffness, the storage bin of embodiment II includes deep and integrated ribs 34 extending generally longitudinally toward the front edge of the bin, whereas the ribs 35 of the bin of embodiment I are shallow.
FIG. 8 illustrates a support frame 36 for the storage bins of the first and second embodiments of the invention. The frame can be seen, at least in part, in FIGS. 2 and 4, in combination with the bins of the first and second embodiments, respectively. Both bins are mounted to a C-channel sections 37, 38 at the front and rear edges, such sections being made from steel, for example, or other suitable material. Extending between the C-channel sections for the purpose of aiding in the support of the center section of the bins are generally longitudinally extending tubular members 39, shaped to fit the contours of the underside of the bins, in conjunction with attached vertical plates 40. Like the C-channel sections, the tubes 39 and plates 40 can be made from steel or other material. In addition, shapes other than those particularly illustrated for the members 39 and 40 could alternatively be utilized.
As shown in FIG. 7, and in combination with the bin of the second embodiment in FIG. 4, the brackets 41, made of steel or other suitable material, are attached to the flanges 42 at the pockets for the seven and ten pins, which flanges also support the shuttle. The combination of attachments shown in FIG. 8, and in FIG. 4, helps to reinforce both the shuttle and the bin, particularly for adequately supporting the bin if one were to put his/her weight on one of the flanges to prevent the twisting of the rear channel. The increased stiffness of the edges of the second embodiment also increase such reinforcement.
FIG. 9 illustrates respective portions of the storage bins of the first and second embodiments of the invention, with exploded showings of the mounting hardware. For each bin, only one assembly of hardware components is shown in detail, it being understood that the bins are mounted in a plurality of locations along its periphery, for example. The storage bin of the first embodiment I includes a shoulder screw 43 (¼×⅜ inch, #10 thread, e.g.), to extend through a slot 46, a fender washer 44 (¼ in. ID, 1 in. OD, e.g.), a grommet 45 (¼ in. ID, 7/16 in. hole, ⅝ in. OD, e.g.), and a flex lock nut ( 3/16 in., not shown). The storage bin of the second embodiment II includes a cap screw 43 (¼×1 inch, e.g.), to extend through a hole 51, a fender washer 48 (¼ in. ID, 1 in. OD, e.g.), a grommet 49 (⅜ in. ID, 718 in. hole, 1 1/16 in. OD, e.g.), and a flex lock nut (¼ in., not shown).
Grommet diameters play a large role in the extent to which a HDPE bin can expand and contract before damage is done to the bin or to the fasteners holding it. The embodiment I uses a radial grommet 45 having a radial modulus of 3/32 inch. The embodiment II uses a grommet 49 with a radial modulus of ¼ inch, allowing 25% more movement in all directions. The grommet 49 is mounted in a hole 51 rather than a slot (46, e.g.) for the purpose of ensuring proper function of the grommet in all physical situations that would be encountered during use.
FIG. 10 illustrates the storage bin of the second embodiment II with indexing and time stamp features. During the thermoforming manufacturing process described above, after the part which is to become a bin according to the invention is removed from its mold, the part must be removed from its clamping frame, trimmed and routed to create the particular details necessary, such as the openings at the underside of the bin. Such trimming and routing is typically automated and, therefore, the part must be precisely positioned. FIG. 10 illustrates a conical feature 52 to constrain the part in the X and Y directions, as well as a V-groove feature 53 to rotationally constrain the part, throughout the trimming and routing process. In addition, adjacent the conical feature, an in-mold time stamp can be formed on a control surface of the part.
The storage bin assembly of the invention, manufactured and constructed as described above, improves upon prior metal bins and the known bin made by a rotomolding process, providing significant stiffness and impact resistance, not suffering from premature material fatigue, and which can withstand a significant number of impacts with bowling pins, such as at least 1,000,000 cycles of a pin spotting apparatus
The invention is not limited to the particulars of the embodiments described hereinabove as examples, but encompasses any equivalent embodiment. For example, although sheets of a high molecular weight polyethylene (HMWPE) can be used for the storage bins of both the first and second embodiments, the invention encompasses the manufacture from other polymers. In addition, the polymer sheets used for the storage bins of both the first and second embodiments can be formed from 5/16 inch extruded sheets (HMWPE, e.g.). although other thicknesses are also contemplated. In this regard, because of the stiffening described above in connection with the storage bin of the second embodiment, the invention encompasses the manufacture of bins of the second embodiment from ¼ inch thick sheets, which results in savings of material and related processing time, thereby lowering the cost of manufacture.
Patent Application
20080004125
