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Mold for a golf ballRelated Patent Categories: Games Using Tangible Projectile, Golf, Club Or Club Support, HeadMold for a golf ball description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060068931, Mold for a golf ball. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The invention relates in general to an improved golf ball mold having a non-planar parting surface used to manufacture "seamless" golf balls, and more particularly, to a method of defining the non-planar surface using a computerized modeling system. BACKGROUND OF THE INVENTION [0002] The usual golf ball manufacturing techniques include several different steps, depending on the type of ball, such as one, two, three or even more than three piece balls. According to the traditional method, a solid or composite elastomeric core is made, and an outer dimpled cover is formed around the core. [0003] The two standard methods for molding a cover over a core or a core and inner layers are compression molding and injection molding. The compression molding operation is accomplished by using a pair of hemispherical molds each of which has an array of protrusions machined or otherwise provided in its cavity, and those protrusions form the dimple pattern on the periphery of the golf ball during the cover molding operation. A pair of hemispherical cover blanks, are placed in a diametrically opposed position on the golf ball body, and the body with the cover blanks thereon are placed in the hemispherical molds, and then subjected to a compression molding operation. The combination of heat and pressure applied during the molding operation results in the cover blanks being fused to the golf ball body and to each other to form a unitary one-piece cover structure which encapsulates the golf ball body. In addition, the cover blanks are simultaneously molded into conformity with the interior configuration of the hemispherical molds which results in the formation of the dimple pattern on the periphery of the golf ball cover. When dimple projections are machined in the mold cavity they are typically positioned below the theoretical parting line of the resulting mold cavity. The parting line is typically machined after the dimple forming process. For ease of manufacturing the parting line on the cavity is machined flat and perpendicular to the dimpled surface as to provide a positive shut off preventing flowing cover material from leaking out of the mold. This dimple positioning and flat parting line results in a great circle path on the ball that is essentially void of dimples. This is commonly referred to as the equator, parting line, or seam of the ball. Over the years dimple patterns have been developed to compensate for cosmetics and/or flight performance issues due to the presence of the seam. [0004] As in all molding operations, when the golf ball is removed from the hemispherical molds subsequent to the molding operation, it will have molding flash, and possibly other projecting surface imperfections thereon. The molding flash will be located at the fused circular junction of the cover blanks and the parting line of the hemispherical molds. The molding flash will therefore be on the "equator" of the golf ball. [0005] The molding flash and possible other imperfections projecting from the surface need to be removed and this is normally accomplished by one or a combination of the following: cutting blades, sanding belts, or grinding stones, and the like. These types of processes tend to enhance the obviousness of the seam. Alternative finishing processes have been developed to minimize this effect. These processes include tumbling with media, stiff brushes, cryogenic de-flashing and the like. Regardless of the finishing process, the result has been a flat parting line in an area substantially void of dimple coverage. [0006] When flashing is removed by grinding, it is desirable that the molding operation be accomplished in such a manner that the molding flash is located solely on the surface of the golf ball and does not extend into any of the dimples. In other words, a grinding operation may have difficulty reaching into the dimples of the golf ball to remove the molding flash without ruining the golf ball cover. Therefore, prior art hemispherical molds are primarily fabricated so that the dimple-forming protrusions formed therein are set back from the circular rims, or mouths of their cavities. The result is that the equator of a molded golf ball is devoid of dimples and the molding flash is located solely on the smooth surface provided at the equator of the golf ball. [0007] It is well known that the dimple pattern of a golf ball is a critical factor insofar as the flight characteristics of the ball are concerned. The dimples influence the lift, drag and flight stability of the golf ball. When a golf ball is struck properly, it will spin about a horizontal axis and the interaction between the dimples and the oncoming air stream will produce the desired lift, drag, and flight stability characteristics. [0008] In order for a golf ball to achieve optimum flight consistency, its dimples must be arranged with multiple axes of symmetry. Otherwise, it might fly differently depending upon orientation. Most prior art golf balls include a single dimple free equatorial parting line, which inherently limits the number of symmetry axes to one. In order to achieve good flight consistency, it is often necessary to compensate for this limitation by adjusting the positions and/or dimensions and/or shapes of certain dimples. Alternatively, additional symmetry axes can be created by incorporating additional dimple free "false" parting lines. However, this practice increases the amount of un-dimpled surface on the ball, which can result in reduced ball flight distance. [0009] For maximum performance and consistency, it is preferable to use a dimple arrangement that requires no adjustment or addition of false parting lines. Therefore, if it is desirable to eliminate the equatorial parting line, it is best that it be done by including dimples that intersect the equator. Some U.S. patents that seek to place dimples upon the equator of the ball include U.S. Pat. No. 6,632,078 to Ogg et al., U.S. Pat. Nos. 6,200,232, 6,123,534 and 5,688,193 to Kasashima et al., U.S. Pat. No. 5,840,351 to Inoue et al., and U.S. Pat. No. 4,653,758 to Solheim. These patents introduced "stepped" and/or "zig zag" parting lines. While this could potentially improve compliance with the symmetry, they did not sufficiently improve dimple coverage, since the parting lines included straight segments that did not permit interdigitation of dimples from opposite sides of the equator. A stepped path often results in a greater loss of dimple coverage than a straight path because it discourages interdigitation for a larger number of dimples. U.S. Pat. No. 6,936,208 to Ogg teaches the formulation of a partial or continuous tab created by overlapping of adjacent concave and convex tabs to reduce the dimension of the seam about the ball. [0010] Therefore, a need exists for a mold to create a new and improved golf ball, one that would have a parting line configuration that would minimize dimple damage during flash removal, improve symmetry performance, increase dimple coverage, minimize the visual impact of the equator, and create a reduced amount of flash and the effort of removing it. SUMMARY [0011] The present invention provides a mold for forming a castable cover on a golf ball (Example: urethane). The mold contains hemispherical mold cups removably mated along a non-planar parting line, an upper mold cup and a lower mold cup. Both cups have interior cavity details, and when assembled create a generally spherical cavity and also provide a dimple pattern on the golf ball. The upper and lower mold cups have non-planar mating surfaces, wherein each surface comprises a plurality of peaks and valleys which are created by a computerized modeling system. When assembled the parting line follows the dimple outline pattern and allows the dimple outline pattern of one mold cup to interdigitate with the dimple outline pattern of the mating mold cup, thereby forming a golf ball of substantially seamless appearance. The non-planar surface of the upper mold comprises at least three true sprues and three false sprues, and more preferably five true sprues and five false sprues. Another embodiment would include the lower mold having these sprues in the non-planar surface. The false sprues have a recess wherein tabs are added to the cover for use in aligning the golf as it is spun in a buffing machine. The tabs are subsequently removed by a knifing procedure. [0012] The present invention provides for the tabs, which are subsequently removed and discarded, to occupy less than 15% of the non-planar surface. This will substantially reduce the amount of material waste that must be discarded. [0013] The present invention provides a method for molding the non-planar golf ball parting surface comprising the steps of first, creating a 3-dimensional computer model representing the golf ball and then constructing a parting line profile represented as a 2-dimensional curve upon a positioned plane. Secondly, the parting line profile is projected onto a 3-dimensional surface of the golf ball model, which generates a radiated surface that contains the parting line which forms the parting surface of a model of the golf ball mold. Finally, the non-planar parting surface is manufactured on a golf ball mold by use of a CNC machine tool. [0014] The preset invention creates the non-planar parting line profile by use of a computerized modeling system such as either a CAD (Computer Aided Design) or CAE (Computer Aided Engineering). [0015] Another object of the invention is to provide a parting line profile constructed of arc segments that are continuous with one another and that weave a path around and between dimples without intersecting them. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is an enlarged pictorial expanded view of the mold comprising both mold halves showing the vents on the upper mold half. [0017] FIG. 2 is plan view of the upper mold half for a mold designed for a Urethane covered ball. [0018] FIG. 2A is an enlarged view of A on FIG. 2. [0019] FIG. 2B is an enlarged view of B on FIG. 2. [0020] FIG. 3 is a pictorial view of an upper mold describing a vent designed for a Surlyn covered ball. Continue reading about Mold for a golf ball... Full patent description for Mold for a golf ball Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Mold for a golf ball patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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