Abstract
Disclosed herein are various forms of hybrid baseball bats comprising a wood shell having a radial wall and an outer radial surface profile defining a baseball bat. The wood shell having a central core with a central surface thereon extending from a distal end of the bat. The central surface being profiled with a taper that in some embodiments extends entirely through to the proximal end. A fibrous construct is housed in the central core and infiltrated with an epoxy resin. In some forms, the fibrous construct is in the form of a sleeve. Disclosed are various manufacturing techniques for manufacturing hybrid baseball bats including a low pressure bladder method, a high pressure bladder method, and a centrifugal force method.
Claims
1. A method of constructing a hybrid baseball bat comprising the steps of: obtaining a wood billet, trimming the wood billet to a predetermined length, and cutting into the billet an external baseball bat profile; cutting a profiled central surface defining a central core of a wood shell of the baseball bat; infiltrating a fibrous sleeve with an epoxy; covering the central surface with the fibrous sleeve; and applying radial forces to embed the fibrous sleeve in the central surface.
2. The method of claim 1 whereas the step of applying radial forces to embed the fibrous sleeve in the central surface is by the use of one or more of a low pressure method, a high pressure method, and a centrifugal method.
3. The method of claim 1 whereas the step of cutting a profiled central surface defining a central core of a wood shell of the baseball bat further comprises the step of roughening the central surface using machine operations.
4. The method of claim 1 whereas the step of cutting a profiled central surface defining a central core of a wood shell of the baseball bat further comprises the step of cutting the profiled central surface the entire distance from a proximal end to a distal end of the hybrid baseball bat.
5. The method of claim 1 further comprising the step of: sliding an expandable bladder into the internal chamber of said fibrous sleeve; pre-coating the fibrous sleeve with an epoxy and sliding the expandable bladder and fibrous sleeve into the central core of the wood shell.
6. The method of claim 5 further comprising the step of: placing the wood shell, core structure, and bladder in a mold.
7. The method of claim 6 further comprising the step of: inflating the expandable bladder thereby applying a high radial force causing consequent embedding of the fibrous sleeve into the central surface of the central core.
8. The method of claim 7 further comprising the step of: removing the bat from the mold.
9. The method of claim 8 further comprising the step of removing the expandable bladder after the epoxy cures.
10. The method of claim 1 further comprising the step of: spinning the wood shell along its central axis causing consequent embedding of the fibrous sleeve with epoxy into the central surface of the central core.
11. The method of claim 1 further comprising the step of applying at least one of ultraviolet light and radiation to facilitate curing of the epoxy.
12. The method of claim 1 further comprising the step of: seating an end of a flexible rod in a plug aperture of a joiner plug.
13. The method of claim 12 further comprising the step of: positioning the joiner plug in a proximal end of an internal chamber of said fibrous sleeve; and seating the joiner plug, flexible rod, and fibrous sleeve in said central core.
14. The method of claim 12 further comprising the step of: attaching the fiber sleeve on an edge at the first end of the joining plug; inserting the plug and flexible rod assembly into the central core of the wood shell until it is fully seated.
15. The method of claim 1 further comprising the step of: seating the wood shell in a rotary machine and spinning about the elongate axis of the wood shell whereas centrifugal force propels the sleeve and epoxy in an outward direction embedding it into the central surface of the central core.
16. The method of claim 1 further comprising the step of: fixing an end cap into the central core using an adhesive.
17. The method of claim 1 whereas the step of infiltrating a fibrous sleeve with an epoxy further comprises the step of: precoating the fiber sleeve or pouring the epoxy down the fibrous sleeve.
18. The method of claim 1 further comprising the step of radially opening the fibrous sleeve with a forming stick before the step of covering the central surface with the fibrous sleeve.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0089] These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein each drawing is according to one or more embodiments shown and described herein, wherein cross-sectional views are from a plane extending through a central axis, and wherein:
[0090] FIG. 1 depicts a perspective view of a wood billet utilized in the manufacture of a hybrid baseball bat;
[0091] FIG. 2 depicts a perspective view of a hybrid baseball bat;
[0092] FIG. 3A depicts a cross-sectional view through a central axis of a wood shell of a hybrid baseball bat;
[0093] FIG. 3B depicts a cross-sectional view through a central axis of a wood shell of a hybrid baseball bat;
[0094] FIG. 4 depicts a side view of a tapered drill bit utilized for creating a profiled central core in a wood shell of a hybrid baseball bat;
[0095] FIG. 5 depicts a side cross-sectional view of a wood bit utilized to create a profiled central core in a wood shell of a hybrid baseball bat;
[0096] FIG. 6 depicts a side cross-sectional view of a wood shell of the hybrid baseball bat of FIG. 2;
[0097] FIG. 7 depicts a perspective cross-sectional view of the wood shell of the hybrid baseball bat of FIG. 2;
[0098] FIG. 8 depicts a perspective cross-sectional view of the hybrid baseball bat of FIG. 2;
[0099] FIG. 9 depicts a perspective view of the two-part epoxy layer of the hybrid baseball bat of FIG. 2;
[0100] FIG. 10 depicts a cross-sectional perspective view through a central axis of the two-part epoxy layer of the hybrid baseball bat of FIG. 2;
[0101] FIG. 11 depicts a perspective view of the fibrous construct of the hybrid baseball bat of FIG. 2;
[0102] FIG. 12 depicts a cross-sectional perspective view through a central axis of the fibrous construct of the hybrid baseball bat of FIG. 2;
[0103] FIG. 13 depicts a perspective view of an end cap used for the enclosing the central core at the distal end of a hybrid baseball bat;
[0104] FIG. 14 depicts a side cross-sectional view of a hybrid baseball bat utilizing a flexible rod and joiner plug;
[0105] FIG. 15 depicts a side view of a flexible rod utilized in the hybrid baseball bat of FIG. 14;
[0106] FIG. 16 depicts a side view of a joiner plug utilized in the hybrid baseball bat of FIG. 14;
[0107] FIG. 17 depicts a side view of a fibrous sleeve and end cap utilized in the hybrid baseball bat of FIG. 14;
[0108] FIG. 18 depicts a flow chart view of various methods of manufacturing a hybrid baseball bat;
[0109] FIG. 18B depicts a flow chart view of various methods of manufacturing a hybrid baseball bat;
[0110] FIG. 19 depicts a perspective cross-sectional view of a wood shell with roughened central surface;
[0111] FIG. 20 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a centrifugal force method;
[0112] FIG. 21 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a centrifugal force method;
[0113] FIG. 22 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a centrifugal force method;
[0114] FIG. 23 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a centrifugal force method;
[0115] FIG. 24 depicts a perspective view of a wood shell during the course of manufacture;
[0116] FIG. 25 depicts a perspective view of the central core of a wood shell during the course of manufacture;
[0117] FIG. 26 depicts a perspective view of the central core of a wood shell during the course of manufacture;
[0118] FIG. 27 depicts a perspective view of a flattened fibrous sleeve;
[0119] FIG. 28 depicts a perspective view of a fibrous sleeve during expansion by a forming stick;
[0120] FIG. 29 depicts a perspective view of the fibrous sleeve of FIG. 27-28 being introduced into the central core of a wood shell;
[0121] FIGS. 30 and 31 depicts a perspective view of a fibrous sleeve housed in a central core;
[0122] FIG. 32 depicts a perspective view of a hybrid baseball bat being spun at high speed during the course of manufacture using a centrifugal method;
[0123] FIG. 33 depicts a perspective view of the end cap depicted in FIG. 32 after trimming;
[0124] FIG. 34 depicts a perspective view of an inflatable bladder during the course of manufacture using a low pressure method;
[0125] FIG. 35 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a low pressure method;
[0126] FIG. 36 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a low pressure method;
[0127] FIG. 37 depicts a perspective view of a fibrous sleeve and inflatable bladder during the course of manufacture using a low pressure method;
[0128] FIG. 38 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a low pressure method;
[0129] FIG. 39 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a low pressure method;
[0130] FIG. 40 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a low pressure method;
[0131] FIG. 41 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a high-pressure method;
[0132] FIG. 42 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a high-pressure method;
[0133] FIG. 43 depicts a perspective view of an expandable bladder seated in a fibrous sleeve during the course of manufacture of a hybrid baseball bat using a high-pressure method;
[0134] FIG. 44 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a high-pressure method;
[0135] FIG. 45 depicts a perspective view of a hybrid baseball bat seated in a first mold form during the course of manufacture using a high-pressure method;
[0136] FIG. 46 depicts a perspective cross-sectional view of a hybrid baseball bat seated between a first and second mold form during the course of manufacture using a high-pressure method;
[0137] FIG. 47 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a high-pressure method;
[0138] FIG. 48 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a high-pressure method;
[0139] FIG. 49 depicts a perspective cross-sectional view of a hybrid baseball bat during the course of manufacture using a high-pressure method.
DETAILED DESCRIPTION OF SELECTED EMBODIMENTS OF THE INVENTION
[0140] Select embodiments of the invention will now be described with reference to the Figures. Like numerals indicate like or corresponding elements throughout the several views and wherein various embodiments are separated by letters (i.e. 100, 100B, 100C). The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive way, simply because it is being utilized in conjunction with detailed description of certain specific embodiments of the invention. Furthermore, embodiments of the invention may include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the invention described herein.
[0141] FIG. 2 illustrates one embodiment of the article of invention before placement of optional grip 127 and application of final wood sealants. Hybrid baseball bat 100A is illustrated in an otherwise finished configuration comprising a wood shell 103A, a radial surface 112A on the wood shell, an enlarged knob portion 130A at a proximal end 105A, an enlarged barrel portion 118A at a distal end 107A, and a taper portion 122A intermediate the handle portion 126A and barrel portion 118A. An end cap 134A seals the distal end (also FIG. 13). A core structure 140A (FIG. 8) housed in a central core 114A reinforces the wood shell 103A. The hybrid baseball bat comprises a variety of materials including but not limited to wood such as maple and birch utilized in the wood shell 103A. The hybrid baseball bat 100A can comprise a variety of materials including but not limited to composites such as carbon fiber, resin, fiberglass, and Kevlar. In this embodiment, the core structure 140A comprises a carbon fiber sleeve with a cured two-part epoxy.
[0142] The central core 114B in some embodiments extends the entire length of a wood shell 103B from a proximal end to a distal end as illustrated in FIG. 3A whereas in other embodiments, the central core 114C only extends partially into the handle portion 126C as illustrated in FIG. 3B or alternatively only into the barrel portion and taper portion. The barrel portion, taper portion, handle portion and knob portions each have a respective core portion in the central core 114B and are thus termed a barrel core 120B, a taper core 124B, a handle core 128B, and a knob core 132B. Central core 114B comprises a profiled central surface 116B defining central core 114B. The profiled central surface 116B and radial surface 112B define a radial wall 110B extending therebetween and forming wood shell 103B.
[0143] In preferred embodiments, the hybrid baseball bats disclosed are manufactured from a wood billet 101 that is substantially cylinder shaped as illustrated in FIG. 1. Here, the wood billet is greater than 34 inches long with a diameter greater than 2.625 inches and preferably wood billet 101 is approximately 37 inches×2.8 inches. The wood billet 101 comprises a billet body 102 with an outer surface 104 and has a first billet end 106 and a second billet end 108. The outer surface 104 of the billet body is machined to create a profiled radial surface recognizable to baseball bats with maximum diameter in the barrel portion and a minimum diameter in the handle portion.
[0144] In some embodiments, the central core of the hybrid baseball bat is created by drilling using one or more drill bits such as the tapered drill bit 202 illustrated in FIG. 4. Note that the outer cutting surface of the tapered drill bit varies in diameter forming a profiled central surface 116B. Radial wall 1108 remains between the outer profiled radial surface 112B and central surface 116B. Alternatively, the central core 114B is created by a one or more wood bits 200 that are driven by one or more of a lathe and CNC machine as illustrated in FIG. 5. In other embodiments, the central core is created by gun drill wood bits 201 advanced in a gun drilling machine. Air pressure can be introduced during gun drilling of the central core to remove wood chips and reduce heat buildup during cutting operations. Wood bits 200 utilized to create the central core include but are not limited to one or more of normal/standard, forstner, gun drill, and CNC cutting bit. The central core is describable in profile as but not limited to: uniform, variable, concave, and negative through any portion of the central core.
[0145] In some embodiments such as illustrated in FIG. 6-8, central surface 116A and radial surface 112A are profiled such that each surface of the wood shell is continuous and absent of obvious steps except for at the junction of the knob portion and handle portion on the radial surface. Comparatively, note step 115B in FIG. 3A illustrating an interrupted central surface. In this embodiment (FIG. 6), the radial wall thickness in the wood shell is substantially uniform with slight variation between the radial wall thickness in the barrel portion (B) which measures about 0.3 inches and the radial wall thickness in the handle portion (H) which measures about 0.21 inches. In other embodiments, the central surface is profiled to provide a consequent variable radial wall thickness, tapered wall design.
[0146] FIGS. 9-12 illustrates various layers of a core structure of the hybrid baseball bat 100A illustrated in FIGS. 2 and 8. FIGS. 9-10 represents the two-part epoxy 148A layer which in an un-finished configuration is uncured and infiltrates fibrous construct 141A and bonds to the central surface 116A of the radial wall 110A of wood shell 103A before curing in place in a finished configuration. The fibrous construct 141A comprises a plurality of high strength fibers 142A in the form of a weave 144A which can have general shape manipulated for use in the central core. In preferred embodiments for example, the fibrous construct 141A is in the form of a fibrous sleeve 150A having an outer face 160A and an inner face 158A defining an internal chamber 151A. The fibrous sleeve can have a bi-axial weave pattern. The high strength fibers 142A used in the hybrid baseball bat 100A are arranged and can be varied in weave type, weave direction, weave thread count (density), weave thickness, and weave layers to produce a desired hybrid bat performance characteristic such as bat weight, bat center of gravity, bat stiffness, and bat ductility. Further each of these weave parameters can be varied depending on the location. For example only, the weave thickness may be greater in the barrel portion as compared to the handle portion. The hybrid bat illustrated in FIG. 6 comprises a much larger diameter barrel core 120A compared to the handle core 128A. The corresponding fibrous sleeve used in this bat is substantially 2 inches in diameter in a barrel portion and substantially 0.5 inches in a handle portion of the sleeve and tapering between these two diameters in a taper portion 122A.
[0147] Fibrous construct 141A can be manufactured from a variety of high strength fibers not limited to carbon fiber and Kevlar. In alternative forms, the fibrous construct 141A is in the form of a fibrous mesh 149A such as a sprayed mesh 146A formed by utilizing a spray head to spray a mix of high strength fibers and epoxy mix on to the central surface of the central core forming a high strength core structure that is embedded in the wood shell upon curing. Other variations include varying types of two-part epoxy 148A used in the hybrid baseball bat 100A to produce a desired hybrid bat performance characteristic such as bat weight, bat center of gravity, bat stiffness, and bat ductility.
[0148] A weave 144A formed from high strength fibers 142A is varied in diameter and shape through exertion of one or more of internal and external forces during the hybrid baseball bat manufacturing process. For example, fibrous sleeve 150A, with an initial stiffness like a hollow rope, can begin ‘formless’ or otherwise in the shape of a flattened tube in an unfinished configuration before opened and expanded to its final cylindrical tube form inside the central core 114A of the hybrid baseball bat 100A in a finished configuration. The aforementioned forces cause the weave 144A to be embedded in wood shell 103A of the hybrid bat by an outward radial force directed from a central axis (axis A). These outward radial forces can be due for example from one or more of: a forming stick 162 pushed down the internal chamber 151A, inflation of an expandable bladder inside the central chamber, and centrifugal force as a consequence of high speed rotation of the wood shell along the central axis. Forming stick 162 in preferred forms is an elongate cylindrical bar made of wood or plastic.
[0149] FIGS. 14-17 illustrates from a cross-sectional view one embodiment of a hybrid baseball bat with internal core structure 140C. The core structure is operable to add strength and support to the wood shell 103C of the hybrid baseball bat. The core structure 140C comprises a flexible rod 154C with a distal end of the flexible rod housed in the plug aperture 153C of a joiner plug 152C. The joiner plug 152C resides in the proximal end of the internal chamber 151C of fibrous sleeve 150C which is infiltrated with two-part epoxy 148C. The core structure (flexible rod, joiner plug, fibrous sleeve infiltrated with epoxy) is housed in the central core 114C of wood shell 103C (FIG. 3B). This configuration maximizes handle portion strength, minimizes pre-mature handle fracture, provides increased handle portion flexibility, and minimizes negative handle vibrations.
[0150] Joiner plug 152C has an outer surface sized and shaped for seating at the proximal end of barrel core 120C. In this embodiment, joiner plug 152C is substantially conical shaped whereas plug aperture 153C is a cylindrical through hole extending through the central axis of the plug. In a finished configuration, a portion of fibrous sleeve 150C is sandwiched between central surface 116C and the outer surface of the joiner plug 152C as illustrated in FIG. 14.
[0151] As noted in earlier embodiments, core structure 1400 comprises a formless fiber sleeve in a pre-finished configuration that is flexible and can expand and contract as necessary to fit the profile of the central core as defined by the profiled central surface 116C, Optionally, a portion of central surface 116C is roughened by one or more operations including but not limited to scouring, grooving, sanding, rifling, and other processes known in the art to ensure the tightest and strongest fit and adhesion to the bat's internal walls. Roughening 117A by rifling of a central surface is illustrated in FIG. 19.
[0152] As noted in FIGS. 3A, 3B, and 6, the wood shell incorporates a profiled central surface on the radial wall as a base on which the fiber sleeve can adhere. The profiled central surface of the radial wall can be formed by a variety of operations. For example, a tapered drill bit 202 introduced on a lathe may be used to form central core 114 (FIG. 4). The outer face of the tapered drill bit comprises the complementing central surface contour to create the barrel core. Alternatively, the profiled central surface 116B of the radial wall 110B is formed by a wood bit 200 driven by a CNC machine programmed to create the tapered profile of the central surface as illustrated in FIG. 5. The CNC lathe is used to shape the central surface of the radial wall based on a programmed profile. This method maximizes the barrel cavity while minimizing stress concentration points in the radial wall. In addition, a drill bit extension can be utilized along the same axis to drill partially into or through the handle portion of the hybrid baseball bat thereby creating a space to refill with a more flexible material than wood. This flexibility minimizes negative vibrations felt at any point of contact of the baseball on the bat and minimizes handle breakage.
[0153] In one form, a method of constructing a hybrid baseball bat 100C (FIG. 14) comprises the following steps (FIG. 18) with each step listed in (XXX). Obtaining a wood billet sufficient in length to make a one piece full length wood shell (i.e. knob to end cap). Trimming the wood billet to a predetermined length and cutting the external bat profile into the radial surface (250) (cutting profile can be delayed until the end). Forming the profiled central surface of the central core using a machine operation such as one or more of but not limited to: gun drilling, wood bit boring, and drilling with tapered drill bit (252). Optionally, roughening the central surface by one or more operations such as rifling (254). Obtaining a flexible rod of a predetermined length and sized for housing in the handle core. Obtaining a joiner plug of a predetermined size for fit into the proximal end of the barrel core of the hybrid baseball bat (256). Fixing the joiner plug to one end of the flexible rod by inserting the flexible rod end into the plug aperture of the joiner plug (258). Obtaining a formless fibrous sleeve sired to house the joiner plug therein at one end (260) and positioning the joiner plug in the fiber sleeve accordingly with the remaining flexible rod extending proximally away from the fibrous sleeve. Sliding the fibrous sleeve over the joining plug and attaching the fiber sleeve on an edge at the proximal end of the joining plug. Inserting the fibrous sleeve, joiner plug, and flexible rod assembly into the central core from the distal end (262). If necessary, radially opening the fibrous sleeve using a forming stick inserted down its internal chamber to approximate the outer face with the central surface of the wood shell. Removing the forming stick (264). Sliding the fiber sleeve, joiner plug and flexible rod assembly into central core of the wood shell. (266). Pouring an epoxy mix down the central core (alternatively, the fibrous sleeve and flexible rod may be pre-wetted with epoxy) (268). Fixing the end cap at the distal end of the central core with adhesive (alternatively, the end cap may be inserted after epoxy curing operations depending on the requirements of the final operations in use). Adhering the fiber sleeve to the central surface of the central core by one of three methods: a low pressure bladder method, a high pressure bladder method, and a centrifugal force method (272) as described in the following paragraphs (272).
[0154] In one form, a method of constructing a hybrid baseball bat 100A. (FIG. 2, 8) comprises the following steps (FIG. 18B) with each step listed in (XXX) form. Obtaining a wood billet sufficient in length to make a one-piece full length wood shell. Trimming the wood billet to a predetermined length and cutting the external bat profile into the radial surface (250) (cutting profile can be delayed until the end). Forming the profiled central surface of the central core using a machine operation such as one or more of but not limited to: gun drilling, wood bit boring, and drilling with tapered (hill bit (252). Optionally roughening the central surface by one or more operations such as rifling (254). Obtaining a formless fibrous sleeve substantially the length of the central core (294). If necessary, radially opening the fibrous sleeve using a forming stick inserted down its internal chamber to approximate the outer face with the central surface of the wood shell (264). Inserting the fibrous sleeve into the central core from the distal end of the wood shell and aligning to cover the exposed central surface (296). Removing the forming stick if not already removed. Pouring an epoxy mix down the central core (268) (alternatively, the fibrous sleeve may be pre-wetted with epoxy). Fixing the end cap at the distal end of the central core with adhesive (282) (alternatively, the end cap may be inserted after epoxy curing operations depending on the requirements of the final operations in use). Adhering the fiber sleeve to the central surface of the central core by one of three methods: a low pressure bladder method, a high pressure bladder method, and a centrifugal force method as described in the following paragraphs (272).
[0155] In the low pressure bladder method (FIG. 18, 18B), the process begins with sliding an expandable bladder into the internal chamber of the fibrous construct (274). Inflating the bladder thereby applying a low pressure (i.e. 10 psi) radial force (276) that causes a consequent embedding of the fiber sleeve in the central surface of the central core thus maximizing durability and minimizing potential delamination between the wood shell and sleeve during use. Using this method, the radial wall operates as the mold walls for the curing fibrous construct (i.e. fiber sleeve). Applying one or more optional measures such as heat and UV radiation to accelerate quality bonding (278). Removing the bladder after the epoxy cures (280). Fixing the end cap at the distal end of the central core with adhesives. Then forming a preferred external profile of the hybrid bat utilizing a wood bit in a standard or CNC lathe. Alternatively, the step of forming an external profile of the hybrid baseball bat may be completed as an earlier step in the hybrid baseball bat forming process.
[0156] FIGS. 35-40 depict cross-sectional views of a hybrid baseball bat during various stages of manufacturing using the low pressure bladder method. FIG. 34 illustrates one form of an inflatable (expandable) bladder 204 utilized in the hybrid baseball bat forming operations. On one end is an inlet 205 for inflating and deflating the bladder. Note that the bladder has an external contour of varied diameters for fit into the central core 114A of wood billet 101A (termed a wood billet vs a wood shell due to delayed cutting of external profile). FIG. 35 illustrates a wood billet 101A after gun drilling the central core and with the optional step of roughening 117A the central surface in FIG. 36. In FIG. 37 the fibrous sleeve 150A is pulled over the inflatable bladder and infiltrated with 2-part epoxy 148A. The fibrous sleeve and bladder are inserted into the central core then the bladder inflated to a low pressure (FIG. 38). Heat and pressure may be applied until fully cured. The bladder is deflated and removed (FIG. 39). The end cap is put in place, trimmed, and radial surface 112A profiled.
[0157] In the high pressure bladder method (FIG. 18, 18B), the process begins with sliding an expandable bladder into the internal chamber of the fibrous construct (274). Placing the wood shell with core structure (i.e. fibrous construct, epoxy, flexible rod, joiner plug) into a first mold form 210 having a first hybrid bat cavity 211 (284) and fixably mating with a second mold form 212 having a second hybrid bat cavity 213 (285). Inflating the bladder thereby applying a high pressure (286) (i.e. 100 psi) radial force that causes a consequent embedding of the fiber sleeve in the central surface of the central core thus maximizing durability and minimizing potential delamination between the wood shell and sleeve during use. Here, the mold forms reinforce the radial wall of the wood shell preventing fracture as a result of the high internal bladder pressure. Applying one or more optional measures such as heat and UV radiation to accelerate quality bonding (278). Removing the hybrid baseball bat from the mold after the epoxy cures (288). Removing the expandable bladder after the epoxy cures (280). Fixing the end cap at the distal end of the central core with adhesives (282). Then, forming a preferred external profile of the hybrid bat utilizing a wood bit in a standard or CNC lathe. Alternatively, the step of forming an external profile of the hybrid baseball bat may be completed as an earlier step in the hybrid baseball bat forming process (250).
[0158] FIGS. 41-49 depict cross-sectional views of a hybrid baseball bat during various stages of manufacturing using the high pressure bladder method. FIG. 41 illustrates a wood billet 101A after gun drilling the central core 114A and with the optional step of roughening 117A the central surface in FIG. 42. In FIG. 43 the fibrous sleeve 150A is pulled over the inflatable bladder 204 and infiltrated with 2-part epoxy 148A. The fibrous sleeve and bladder are inserted into the central core (FIG. 44). The billet is placed into the first bat cavity 211 the first mold form 210 (FIG. 45). The mold is closed with the second mold form 212 aligning with the second hat cavity 213. The inflatable bladder 204 is inflated with high pressure at bladder inlet 205 with optional heat and pressure until fully cured (FIG. 46). The air pressure is released, the mold opened, and the billet 101A with core structure 140A is removed (FIG. 47). The inflatable bladder 204 is removed (FIG. 48), The end cap 134A is sealed in place, billet trimmed, and radial surface 112A profiled (FIG. 49).
[0159] The centrifugal force method begins with seating the wood shell with core structure (i.e. fibrous construct, epoxy, flexible rod, joiner plug) into a rotary machine such as a lathe (290) and spinning the wood shell with core structure at a high RPM (292) to capture the effects of centrifugal force which propels mass (fibrous construct and epoxy-resin) in an outward direction embedding them into the central surface of the radial wall thereby maximizing durability and minimizing any prospect of delamination. As one example, the wood shell with core structure is spun for 5 minutes at approximately 1,800 rpms and then at 50 rpms until fully cured. The centrifugal method can also incorporate the step of applying one or more additional measures such as heat and UV light to accelerate curing (278). Fixing the end cap at the distal end of the central core with adhesives (282). Then forming a preferred external profile of the hybrid bat utilizing a wood bit in standard or CNC lathe. Alternatively, the step forming an external profile of the hybrid baseball bat may be completed as an earlier step in the hybrid baseball bat forming process (250). As a preference, the central axis of the wood shell substantially horizontal during spinning when using the centrifugal force method.
[0160] FIGS. 20-23 depict cross-sectional views of a hybrid baseball bat during various stages of manufacturing using the centrifugal force method. FIG. 20 illustrates a billet 101A after gun drilling and FIG. 21 after roughening 117A by rifling (optional) the central surface 116A. FIG. 22 illustrates the wood billet 101A with a fibrous sleeve 150A inserted in the central core of the wood billet 101A from the distal end to the proximal end and epoxy 148A poured in from the barrel end, end cap 134A inserted, and spun about axis A in a lathe 203 until cured. In this embodiment, the external profiling of the radial wall 110A is cut forming the completed hybrid baseball bat 100A before final finishing (FIG. 23). FIG. 24 illustrates a wood shell mounted in a lathe 203. In this embodiment, a forstner bit is utilized to begin cutting the central core 114C as illustrated in FIGS. 25 and 26. FIG. 27 illustrates one form of a flattened carbon fiber sleeve 150 in a pre-finished condition. The fibrous sleeve 150 is expanded to roughly a cylindrical shape before insertion into the central core. FIG. 28 illustrates the use of a forming stick 162 driven down the internal chamber 151 of the fibrous sleeve to reform it to be roughly cylindrical. The fibrous sleeve 150 is then guided into the central core 1114C as illustrated in FIGS. 29-31. Epoxy 148 is poured into the central core 114C and the end cap 134C joined with the wood shell 103C. The wood shell 103C is then spun at high speed to disperse the epoxy into the central surface and fibrous sleeve (FIG. 32). The end cap 134C is trimmed (FIG. 33) and the exterior of the hybrid bat is treated with a wood finish.
[0161] If desired, at the completion of other manufacturing operations, one or more of the radial surfaces, end cap, and proximal end of the hybrid bat can be finished with one or more of stains and sealants.
[0162] It is noted that the terms “substantially” and “about” and “generally” may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
[0163] The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention.
