US20040209716A1

US20040209716A1 - Composite softball bat with inner sleeve

Info

Publication number: US20040209716A1
Application number: US10/844,476
Authority: US
Inventors: Matthew Vacek; George Griffith
Original assignee: Miken Composites Co LLC
Current assignee: Miken Sports LLC
Priority date: 2001-01-19
Filing date: 2004-05-12
Publication date: 2004-10-21

Abstract

A softball bat is made substantially out of composite material. The main portion of the bat includes a substantially tubular hitting surface, a taper, and a handle. A plurality of sleeves are added within the hitting surface to form a flexible bat.

Description

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 10/438,196 filed May 14, 2003, which is a continuation-in-part application of U.S. patent application Ser. No. 09/883,790 filed on Jun. 18, 2001, which claims priority under 35 U.S.C. 119(e) from U.S. Provisional Application Ser. No. 60/263,020 filed Jan. 19, 2001, which applications are incorporated herein by reference.[0001]

FIELD OF THE INVENTION

The present invention relates to the field of bats and more particularly to a softball bat.

BACKGROUND OF THE INVENTION

For many years softball bats were made of wood. Traditional athletic bats comprised of wood are expensive and consume valuable natural resources. A disadvantage of wood bats is that they frequently break during use. A further disadvantage of wood bats is that they are exceedingly difficult to design for consistent performance, given the inconsistency of the natural material. In addition, wooden bats are made of ash or very hard pine. The sources of such woods are becoming increasingly scarce.

In the past fifteen or twenty years, softball bats made of metal were introduced. Metal bats, although more durable than wood bats, also have problems. One of the many problems associated with a metal bat is that the material is fixed and, as a result, so are the parameters of the material. Metal bats have a fixed density and a given weight. As a result, the engineering parameters that can be varied can only be varied within a limited range.

Currently, metal softball bats are more commonly used than wooden softball bats. A common structure in various non-wooden softball bats includes a hollow bat made with a handle and a hitting surface. The hitting surface includes a tubular portion and a sleeve fit inside the tubular portion. The sleeve is also made of metal. The metal bat and sleeve construction has problems. Several of the problems associated with metal softball bats having metal sleeves stems from the impact or large shock load exerted on the metal bat as a result of hitting the softball. The shock loading produces extremely large forces between the bat and the ball. The result is that the metal bat dents when a ball is hit. In other words, the metal may dent in some form when the ball is hit. Some dents are small and some dents are large. Regardless of the size of the dent, energy is lost every hit since some of the energy is used to dent the metal rather than transferred to the softball. The dents also result in a less durable bat. Once dented, each subsequent hit is a further cold working of the metal. In some instances, a microscopic crack can also be formed as the result of denting of the bat. The crack will get bigger and bigger until the amount of material left fails due to shock loading. Many bats fail quickly. Some bats may fail after as few as twenty-five hits.

More recently, composite bats have been introduced. Composite bats include a reinforced plastic with a metal portion. For example, U.S. Pat. No. 4,546,976 which issued to T. N. Jones on Oct. 15, 1985, discloses a reinforced plastic bat with a separate handle section that is softer than the hitting section. Another example is U.S. Pat. No. 4,569,521 which issued to A. W. Mueller on Feb. 11, 1986, which discloses a composite bat having a tapered aluminum spar encased in polyurethane foam in order to provide stiffness and freedom from excessive vibrations. Currently, composite bats have composite shells and metal inner sleeves in the hitting portion of the bat. These bats have some of the same problems as a metal bat. In a composite bat, the metal sleeves dent over time and the impact energy that should be transferred to the ball is absorbed by denting the metal sleeve.

U.S. Pat. No. 5,722,908 issued to Feeney et al. on Mar. 3, 1998, discloses a composite bat with a metal barrel, and a method of fabricating same. The bat has a frame having a recess and fabricated of a composite material of fibers in a matrix binder. A metal sleeve is inserted over the recess of the frame, which forms a hitting surface.

What is needed is a more durable softball bat. What is also needed is a bat which will not dent so that more energy is transmitted or applied to the softball. Another way of looking at this is that what is needed is a bat which will not dent so that little or no energy is wasted denting the bat. Also needed is a bat which will not dent or be cold worked such that an inherent weak spot is formed.

SUMMARY OF THE INVENTION

A softball bat is made entirely out of composite material. The main portion of the bat includes a substantially tubular hitting surface and a handle. A composite sleeve is added within the hitting surface. The sleeve is made of composite material. The hitting surface is also made of composite material.

Advantageously, the composite material has a lower density than metals used to make bats, such as aluminum or titanium. As a result, more material can be used resulting in a more durable bat for a given weight of bat. The composites also have a higher strength than aluminum and titanium and their alloys. Therefore, a stronger bat can be produced. In addition, the composite does not dent and therefore more energy is transferred to the ball. There is less, if any, energy wasted on denting the bat or the inner sleeve. Therefore, the inventive bat hits farther than a wooden or metal bat or bat having metal parts. The inventive bat is made entirely of composite material. Composite material can be made either more stiff or more flexible than a metal bat. The design parameters of a composite are more flexible so that either a more flexible or stiffer bat can be formed by varying the engineering parameters. The additional flexibility in using composite material allows designers to form bats with selected performance characteristics. If the bat is made to be more flexible, the inventive bat has a durability advantage since the bat does not dent and begin the somewhat slow process of failing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a ball bat, with a portion of the tubular hitting surface broken away to show a sleeve according to the present invention. [0011]
FIG. 2 is a longitudinal sectional view of the ball bat of the present invention with the end cap exploded away and showing the composite inner sleeve. [0012]
FIG. 3A is an enlarged cross section view of the present invention drawn along lines [0013] 3A-3A of FIG. 2.
FIG. 3B is an enlarged cross section view along line [0014] 3B-3B in FIG. 2.
FIG. 3C is an enlarged cross section view along line [0015] 3C-3C in FIG. 2.
FIG. 4A is a plan view of the two initial fiber socks of the bat. [0016]
FIG. 4B is a plan view of the shortened fiber sock placed over the initial sock layers shown in FIG. 4A. [0017]
FIG. 4C is a plan view of the fiber socks of the bat shown in FIG. 4B with an added hoop wrap at the tapered portion of the bat. [0018]
FIG. 4D is a plan view of the fiber socks of FIG. 4C after being covered by another sock. [0019]
FIG. 4E is a plan view of the fiber socks of the bat shown in FIGS. 4A-4D with a hoop wrap added to the handle and part of the tapered portion of the bat. [0020]
FIG. 5 is an exploded perspective view of a set of sheets pre-impregnated fibers and a mandrel used to form the inner sleeve of the present invention. [0021]
FIG. 6 is a plan view of the fiber layers on the mandrel being wrapped with a layer of tape. [0022]
FIG. 7 is a cross sectional view of the mandrel with a set of sheets and three layers of tape wrapped around the mandrel. [0023]
FIG. 8 is a perspective cutaway view of the fiber layers in the sleeve. [0024]
FIG. 9 is a longitudinal sectional view of another embodiment of the ball bat of the present invention with the end cap exploded away and showing the composite inner sleeve. [0025]
FIG. 10 is an enlarged cross section view along line [0026] 10-10 in FIG. 9.
FIG. 11 is an exploded perspective view of a set of sheets pre-impregnated fibers and a mandrel used to form the inner sleeve of the present invention. [0027]
FIG. 12 is a plan view of the fiber layers on the mandrel being wrapped with a layer of tape. [0028]
FIG. 13 is a cross sectional view of the mandrel with a set of sheets and three layers of tape wrapped around the mandrel. [0029]
FIG. 14 is a perspective cutaway view of the fiber layers in the sleeve. [0030]
FIG. 15 is a perspective view of a set of sheets wrapped about a mandrel used to form a bat according to another embodiment of the invention. [0031]
FIG. 16 is a top view of a sheet of layup material used in one embodiment of a bat. [0032]
FIG. 17 is a top view of a mandrel like the one shown in FIG. 15 within a mold for a bat. [0033]
FIG. 18 is a schematic view of one embodiment of a fixture for measuring the flexibility of a bat.[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. [0035]
The invention described in this application is useful with all mechanical configurations of bats including softball bats and baseball bats. FIG. 1 is an exploded view of one type of a [0036] bat 100 having a substantially tubular hitting surface 110 and a handle 120. The ball bat 100 is made of composite material. The main portion of the bat 100 includes a substantially tubular hitting surface 110. A handle 120 is attached to the hitting surface. The handle 120 and barrel are integral in the bat shown in FIG. 1. It should be noted that the bat could be formed of a separate handle 120 and tubular hitting surface or barrel 110. The tubular hitting surface 110 and the attached handle 120 form the body 140 of the bat. The diameter of the handle 120 is less than the diameter of the tubular hitting surface 110 and therefore the body 140 of the bat includes a tapered portion 114 which is positioned between the handle 120 and the tubular hitting surface 110. A composite sleeve 112 is added within the body 140 of the bat and more specifically within the tubular hitting surface 110.
The [0037] sleeve 112 of the bat 100 is also made of composite material. Therefore, both the hitting surface 110 and the sleeve 112 are made of composite material. The inner sleeve 112 fits inside the hitting surface 110 of the bat 100. The inner sleeve 112 is made of a composite material which includes a fiber and a resin. The fibers can be made of Kevlar, graphite, carbon, boron, rayon, nylon, fiberglass, other plastics or other polymer materials. Graphite nano tubes may also be used. The resin or binding material may include thermosetting resin systems, epoxies, ceramics, or thermoplastics. The fibers are impregnated with a resin to form a composite material. A plug 130 is molded to the free end of the hitting surface 110. The plug 130 is typically molded into the free end of the bat 100 using a separate process.
FIG. 2 shows the [0038] bat 100 assembled and partially cut away along the length of the bat 100. The sleeve 112 is positioned within the substantially tubular hitting surface 110. In other words, the barrel of the bat is hollow. In the embodiment shown, the sleeve 112 is placed so that it tightly fits within the barrel or tubular batting surface 110. The plug 130 is also molded into the free end of the bat 100. The bat 100 is formed and made according to a resin transfer molding process.
The [0039] body 140 of the bat 100 is comprised of a continuous resin matrix reinforced with a plurality of circumferentially-extending fiber socks 324, 326, shown in FIGS. 3A, 3B, 3C and 4 and two hoops 340, 342. In the preferred embodiment, the resin components consist of Epic S7311 part A and part B available from Epic Resins of Omera, Wis., although other resin components may be used in alternative embodiments. Also, in the preferred embodiment the fiber socks 324, 326 are cross woven and are comprised of 74% glass fiber and 26% carbon fiber, by weight. Of course, other types of weaves and other fibers may be used in alternative embodiments.
This particular combination of resin components and [0040] fiber socks 324, 326 results in a high-strength yet flexible body 140. When a ball impacts the bat 100 during the batter's swing, the bat undergoes a localized deformation conforming to the contact area of the ball, as well as radial or hoop deformation (i.e., the cylindrical bat temporarily deforms into an oval when viewed in cross section). This deformation provides a springboard or trampoline effect which further enhances the hitting zone of the bat 100 and provides maximum velocity to the ball when hit by the bat. The trampoline effect provides distance to a particular hit.
In the preferred embodiment, three fiber socks [0041] 324 a fiber sock 326 and two hoop wraps 340, 342 are used to form the body 140 of the bat 100. The fiber socks 324 are concentrically arranged within the resin matrix of the body 140. FIGS. 4A to 4E illustrate the various layers of the bat as the bat is built up. As shown in FIG. 4A, initially two fiber socks 324 are placed on a mandrel. The two fiber socks 324 cover the body of the bat. As shown in FIG. 4B, a sock 326 is placed over the handle 120 and a portion of the tapered portion of the body of the bat. The next step, shown in FIG. 4C, is a hoop wrap 340 around the tapered portion of the bat and specifically around the two socks 324 and shortened sock 326. A first hoop wrap 340 is done with carbon fiber wrap which is advanced {fraction (3/32)} inches per wrap. The first hoop wrap 340 covers the tapered portion of the body 140 of the bat. The hoop wrap 340 reduces the bulk of the socks 324, 326 and provides added strength to the tapered portion of the finished bat. The hoop wrap 340 is done with carbon fiber wrap which is advanced {fraction (3/32)} inches per wrap. As shown in FIG. 4D, after the initial hoop wrap 340, another fiber sock 324 is placed over the body 140 of the bat. As shown in FIG. 4E, a second hoop wrap 342 is then placed over the bat and overlaps a portion of the first hoop wrap 340. The second hoop wrap 342 is done over the handle 120 of the bat and adds strength to the finished bat. The second hoop wrap 342 over the handle 120 removes bulk from the three socks 324 and the sock 326. The hoop wrap 342 is done with carbon fiber wrap and advanced {fraction (3/32)} of an inch per wrap. The three socks 324 substantially extend the entire length of the body 140 of the bat 100, while the sock 326 substantially extends the length of the handle 120 and through a portion of the taper. The tubular hitting surface 110 is also referred to as a barrel. It should be noted the number of socks can be increased or decreased depending on the design parameters.
In other words, the [0042] handle 120 and the tapered area between the barrel 110 and handle 120 are hoop wrapped about the periphery of those surfaces.
Once the [0043] fiber socks 324, 326 are placed on the mandrel and hoop wrap 340, 342 as discussed above, and the mandrel as wrapped, is placed into a mold where resin is injected into the mold. The mold is placed in a press.
After curing, the mandrel and bat is removed from the mold. The bat is cut to length. The [0044] sleeve 112 is then force fit within the barrel or hitting surface 110 of the bat.
Since the [0045] sleeve 112 is made of a composite, the sleeve also provides a trampolining effect in addition to the trampolining effect of the tubular hitting surface 110 of the bat 100. The sleeve 112 is formed of a composite which is more stiff than the composite forming the tubular hitting surface 110 of the bat 100. Like the tubular hitting surface 110, the deformation of the sleeve 112 conforms to the contact area of the ball. The deformation of the sleeve 112 results in radial or hoop deformation where the sleeve 112 temporarily deforms into an oval, when viewed in cross section. Deformation of the sleeve 112 provides an additional springboard or trampoline effect which is in addition to the springboard or trampoline effect associated with the tubular hitting surface 110 of the bat 100. The trampolining effect of the sleeve 112 further enhances the hitting zone of the bat 100 and provides additional velocity to the ball when hit by the bat 100. The trampoline effect provides distance to a particular hit.
The [0046] inner sleeve 112 placed inside the barrel or tubular hitting surface 110 of the bat 100 is made out of a different materials than those used in the body 140. The sleeve 112 includes sheets of inline impregnated fibers also called pre-impregnated (some referred to as pre-preg) material. A series of sheets 500 are laid up to form the layers of the inner sleeve 112. The inner sleeve 112 is substantially cylindrically shaped.
As shown in FIG. 5, the [0047] sleeve 112 is formed by placing the series of four sheets 500 on a cylindrical mandrel 520. There are four layers of lay up which form the series of sheets 500. Two of the layers 501, 502 are at plus or minus 45 degrees. The layer 503 is at 90 degrees and the last layer 504 is at 0 degrees. The fibers within the impregnated or pre-impregnated material are at 0 degrees when they are substantially aligned with a longitudinal axis 522 of the mandrel 520 or a longitudinal axis of the cylinder of the sleeve 112. The fibers within the impregnated or pre-impregnated material may also be said to be at 0 degrees when they are substantially aligned with an axis of the bat 100 running from the center of the tubular end 110 to the center of the handle end 120. The four layers 501, 502, 503, 504 are E-glass fiber impregnated with resin. It should be noted that the sheets 501, 502, 503, 504 can also be any fiber and resin system. It should be noted that the layup angles can change as well as the number of layers and still be within the scope of the invention. For example, in some embodiments layers 501 and 502 may be included in a single sheet.
After the four sheets of pre-impregnated material are placed onto the mandrel, three layers of tape are placed on the four layers of pre-impregnated material as shown in FIGS. 6 and 7. The three layers of tape keep the four layers of [0048] pre-impregnated material 501, 502, 503, 504 tight, to remove voids and remove air pockets. The first layer 601 of tape is a polypropylene tape that is put on with a lead, with a force on the leading edge of approximately 12 to 13 pounds. The first layer 601 of tape is ⅝″ wide. The first layer 601 of tape is wound over the four layers of pre-impregnated material with {fraction (3/64)}″ of feed and {fraction (37/64)}″ overlap. The first layer 601 of tape is actually put on in order to provide a release layer for the sleeve 112. The first layer 601 of polypropylene tape is available from any composite material suppliers.
After the [0049] first layer 601 of tape is placed on the mandrel, a second layer 602 and a third layer 603 of nylon tape are then placed on the mandrel over the first layer 601. The second layer 602 and third layer 603 are nylon tape which provides more pressure which in turn makes a stronger part. The second layer 602 and third layer 603 of nylon tape are available from any composite material suppliers. The second layer 602 and the third layer 603 are each wound onto the previous layer of tape in a similar way as the first layer 601. The second layer 602 and the third layer 603 are wound over the four layers of pre-impregnated material and the first layer 601 with {fraction (37/64)}″ of an overlap. The second layer 602 and the third layer 603 nylon tapes are also ⅝″ wide. The force on the leading edge of the tape is increased for the second layer 602 and the third layer 603 to 15 pounds of lead pressure or pressure on the leading edge. These second layer 602 wrap and the third layer 603 wrap provide strength to the backing and removes any voids and any air pockets that might weaken the sleeve 112 as formed. The second layer 602 and the third layer 603 generally strengthens the bat sleeve 112.
The arrangement on the [0050] mandrel 520, including the layers 501, 502, 503, 504 of pre-impregnated material is then placed into an oven where it is cured for approximately three hours to ensure that the final product is cured. It is recommended that the curing take place for an hour on the pre-impregnated fibers, but curing is done for three hours just to make sure that the sleeve 112 is fully cured. After curing, the sleeve 112 is removed from the mandrel 520. The tape 601, 602, 603 is then removed by merely cutting it off with a utility knife. The first layer 601 polypropylene tape on the inside of course provides a release agent so the layers 601, 602, 603 release very easily from the sleeve.
FIG. 8 is a perspective cutaway view of the fiber layers in the sleeve. The perspective cutaway view of the [0051] sleeve 112 shows the various directions of the individual layers 501, 502, 503 and 504 within the cured sleeve 112.
The next step is to grind off enough of the exterior of the [0052] sleeve 112 so that it can be force fit within the barrel or the tubular hitting portion 110 of the bat 100. Even though the sleeve 112 is force fit within tubular hitting portion 110 of the bat 100, the outer skin or tubular hitting surface 110 is able to flex and bend and elastically deform and act like a springboard or trampoline for the ball. The sleeve 112 also provides a trampolining effect. In addition, the sleeve 112 provides strength and endurance for the shock loading associated with hitting the ball. The sleeve 112 helps launch the ball. Others may describe the bat 100 as having the capability of giving the ball “pop” upon a hit.
It should be noted that there are many different ways to configure the fibers within the [0053] body 140 and within the sleeve 112. One idea is to configure the fibers within the body 140 and within the sleeve 112 so that the vibrational nodes associated with hitting a ball with the bat are away from the handle 120 of the bat. In other words, the fibers within the body 140 and within the sleeve 112 may be changed to tune the bat 100 so that when a user hits the softball at various positions on the tubular hitting surface 110, the vibrational nodes would not be in the handle 120 of the bat. If the vibrational nodes can be moved from the handle 120, then there would be little or no “sting” or the vibration transmitted to the user's hands.
Of course, different lay-ups of materials can be used in forming the [0054] sleeve 112. Furthermore, different types of materials can be used in forming the body 140. Changing materials or the angles of the fibers within the bat and sleeve are considered within the invention. Changing the shape of the bat 100 or using a different backing for the sleeve have also been contemplated.
It should also be noted that the [0055] body 140 of the bat 100 could be made with a composite barrel or hitting surface 110 and the handle 120 and taper could be made of another material such as metal. A sleeve 112 could then be placed within the barrel or hitting surface 110 and this would still be within the scope of this invention. Although the preferred embodiment describes the entire body 140 of the bat 100 made of composite, it is contemplated that the tapered portion of the body 140 and the handle 120 of other material could be substituted and be within the scope of this invention where the hitting surface 100 of composite includes a composite sleeve 112.
Another bat [0056] 900 will now be discussed with respect to FIGS. 9-13. There are several differences between the bat 900 and the bat 100 previously described. One of the differences is that there are multiple sleeves within the bat. In other words, multiple sleeves replace the single sleeve shown in FIGS. 1-8. As shown in FIGS. 9 and 10, there are a plurality of sleeves 1050, 1060 placed within the tubular hitting surface 324 of the bat 900. The plurality of sleeves 1050, 1060 have a combined wall thickness substantially the same as the wall thickness of the single sleeve 112 shown in FIGS. 1-8. The plurality of sleeves 1050, 1060 are more flexible than a single solid sleeve. An analogy can be drawn to a phone book. A phone book with its multiplicity of pages is more flexible than a solid block of wood. Similarly, a number of sleeves 1050, 1060 is more flexible than a single solid sleeve. It should be noted that although only two sleeves 1050, 1060 are shown in FIGS. 9-10, it is contemplated that additional sleeves could be used and this is within the scope of the invention. The flexibility afforded by multiple layers is balanced with the required strength to determine an appropriate number of layers.
As shown in FIG. 11, the [0057] sleeves 1050, 1060 are formed by placing the series of five sheets 1101, 1102, 1103, 1104, 1105 on a cylindrical mandrel 1020. Two layers of lay up 1101, 1102 form the first sleeve 1050 and two layers of lay up 1104, 1105 form the second sleeve 1060. A release layer 1103 is positioned between the first sleeve 1050 and the second sleeve 1060. The release layer 1103 between the first sleeve 1050 and the second sleeve 1060 is made of polypropylene or another suitable release material. The release layer 1103 is a sheet of polypropylene or release material that is placed between sheets 1102 and 1104 in the lay up. The layer of polypropylene provides for a more flexible bat and more specifically a more flexible hitting surface. The layers 1101, 1102 of sleeve 1060 are at plus or minus 30 degrees. The layers 1104, 1105 of sleeve 1050 are also at plus or minus 30 degrees. The fibers within the impregnated or pre-impregnated material are at 0 degrees when they are substantially aligned with a longitudinal axis 1022 of the mandrel 1020 or a longitudinal axis of the cylinder of either the sleeve 1050 or the sleeve 1060. The fibers within the impregnated or pre-impregnated material may also be said to be at 0 degrees when they are substantially aligned with an axis of the bat 100 running from the center of the tubular end 110 to the center of the handle end 120. The four layers 1101, 1102, 1104, 1105 are carbon fiber impregnated with resin. It should be noted that the sheets 1101, 1102, 1104, 1105 can also be any fiber and resin system. It should be noted that the layup angles can change as well as the number of layers and still be within the scope of the invention. For example, in some embodiments, two layers may be included as a single sheet.
After the four sheets of [0058] pre-impregnated material 1101, 1102, 1104, 1105 and the layer of release material 1103 are placed onto the mandrel, three layers of tape are placed on the five layers as shown in FIGS. 12 and 13. The three layers of tape keep the four layers of pre-impregnated material 1101, 1102, 1104, 1105 and the layer of release material 1103 tight and removes voids and air pockets from the lay up. The first layer 1201 of tape is a polypropylene tape that is put on with a force on the leading edge of approximately 7.5 pounds. The first layer 1201 of tape is ⅝″ wide. The first layer 1201 of tape is wound over the five layers 1101, 1102, 1103, 1104, 1105 of material with {fraction (3/64)}″ of feed and {fraction (37/64)}″ overlap. The first layer 1201 of tape is actually put on in order to provide a release layer for the first sleeve 1050. The first layer 1201 of polypropylene tape is available from any composite material suppliers. Of course, it should be remembered that the amount of tension may be changed based on material and thickness of the material used to form the bat.
After the [0059] first layer 1201 of tape is placed on the mandrel, a second layer 1202 and a third layer 1203 of nylon tape are then placed on the mandrel over the first layer 1201. The second layer 1202 and third layer 1203 are nylon tape which provides more pressure which in turn makes a stronger part. The second layer 1202 and third layer 1203 of nylon tape are available from any composite material suppliers. The second layer 1202 and the third layer 1203 are each wound onto the previous layer of tape in a similar way as the first layer 1201. The second layer 1202 and the third layer 1203 are wound over the four layers of pre-impregnated material and layer of release material 1101, 1102, 1103, 1104, 1105, and the first layer 1201 with {fraction (37/64)}″ of an overlap. The second layer 1202 and the third layer 1203 nylon tapes are also ⅝″ wide. The force on the leading edge of the tape is increased for the second layer 1202 and the third layer 1203 to 15 pounds of lead pressure or pressure on the leading edge. The second layer 1202 wrap and the third layer 1203 wrap provide strength to the backing and remove any voids and any air pockets that might weaken the sleeves 1050, 1060 as formed. The second layer 1202 and the third layer 1203 generally strengthen the bat sleeves 1050, 1060.
The arrangement on the [0060] mandrel 1020, including the layers 1101, 1102, 1104, 1105 of pre-impregnated material and the release layer 1103 is then placed into an oven where it is cured for approximately three hours to ensure that the final product is cured. It is recommended that the curing take place for an hour on the pre-impregnated fibers, but curing is done for three hours just to make sure that the sleeves 1050, 1060 are fully cured. After curing, the sleeves 1050, 1060 are removed from the mandrel 1020. The tape 1201, 1202, 1203 is then removed by merely cutting it off with a utility knife. The first layer 1201 polypropylene tape on the inside of course provides a release agent so that all layers 1201, 1202, 1203 release very easily from the second sleeve 1060.
FIG. 14 is a perspective cutaway view of the fiber layers in the sleeve. The perspective cutaway view of the [0061] sleeves 1050, 1060 shows the various directions of the individual layers 1101, 1102, 1104 and 1105 within the cured sleeves 1050, 1060.
The next step is to grind off enough of the exterior of the [0062] sleeves 1050, 1060 so that it can be force fit within the barrel or the tubular hitting portion of the bat 900. Even though the sleeves 1050, 1060 are force fit within the tubular hitting portion of the bat 900, the outer skin or tubular hitting surface is able to flex and bend and elastically deform and act like a springboard or trampoline for the ball. The sleeves 1050, 1060 also provide a trampolining effect. In addition, the sleeves 1050, 1060 provide strength and endurance for the shock loading associated with hitting the ball. The flexibility of the sleeves 1050, 1060 launches the ball. Others may describe the bat 900 as having the capability of giving the ball “pop” upon a hit.
Of course, different lay-ups of materials can be used in forming the [0063] sleeves 1050, 1060. Also, more than two sleeves can be made for fitting within the hitting surface of the bat 900. Furthermore, different types of materials can be used in forming the body 140 of the bat 900. Changing materials or the angles of the fibers within the bat and sleeves are considered to be within the scope of this invention.
It should also be noted that the [0064] body 140 of the bat 900 could be made with a composite barrel or hitting surface 110 and the handle 120 and taper could be made of another material such as metal. Sleeves 1050, 1060 could then be placed within the barrel or hitting surface 110 and this would still be within the scope of this invention. Although the preferred embodiment describes the entire body 140 of the bat 900 made of composite, it is contemplated that the tapered portion of the body 140 and the handle 120 of other material could be substituted and be within the scope of this invention where the hitting surface 100 of composite includes a composite sleeve 112.
FIG. 15 is a perspective view of a set of sheets of pre-impregnated fibers positioned on a mandrel used to form a bat. In FIG. 15, the [0065] mandrel 1520 has a center line 1522. The mandrel 1520 is elongated and has a length approximately equal to the barrel or substantially tubular hitting surface 110. In this particular embodiment of the bat, longer sheets of prepreg material are used to form the barrel of the bat right onto the mandrel 1520. The mandrel 1522 with the layers of prepreg material and layers of polypropylene is then placed directly into a mold 1700 and injected with an appropriate resin material to form the bat. The mold 1700 is shown in FIG. 17. After the bat is formed, it is removed from the mold 1700 and then the mandrel 1520 is removed from the bat as formed so that a separate set of sleeves or a separate sleeve is not formed and then placed into the barrel of the bat after it has been molded. The advantage with respect to this embodiment of the invention is that an entire set of steps is removed from the manufacturing process. In other words, a separate sleeve does not have to be formed and then placed inside the barrel of the bat but rather, in this embodiment of the invention, the bat is molded right around the mandrel. The layup of the various layers is similar to that shown in FIG. 11 which is used to form a separate sleeve in another embodiment. Now turning to FIGS. 15 and 17, the end of the mandrel 1520 which is near the tapered portion 1714 of the mold which corresponds to the taper on the finished bat, is also tapered so as not to produce a weak spot in the molded material which is placed over the mandrel and over the layers that are laid up atop the mandrel. In other words, the mandrel 1520 has an end 1720 which has a feathered layer of several layers of material used to form the bat. The feathering prevents a thinner portion in the wall of the bat near the end of the mandrel or near the end 1720 of the mandrel that is near the taper 1714. The end of the mandrel is tapered or feathered and more specifically, the end of the layer atop the mandrel is layered or feathered so that there is no weak portion or weak spot formed.
FIG. 16 shows a top view of a sheet used to wrap about the [0066] mandrel 1520. The sheet 1600 is cut into two portions 1610 and 1620. The sheet is cut along a diagonal line 1630. The dimensions of 1610 and 1620 are set so that the two halves, when rolled or applied to the mandrel 1520, will roll on with a taper due to the diagonal cut. The ends 1612 and 1622 of the sheet will each be laid up on the end of the mandrel which is toward the end of the barrel of the bat. The portion along the diagonal cut 1620 will be laid up or placed at the end 1720 of the layers or of the mandrel 1520. Advantageously, by making a diagonal cut when the layers are placed upon the mandrel, it is self-tapering. Furthermore, by placing the cut, the sheets 1600 used to form the layup on the mandrel 1520, can be made to be self-tapering without wasting any extra material. The length of the sheet 1610 between the end 1612 and the cut line 1630 is shorter than the length between the end 1622 and the cut line 1630. Therefore, the portion 1620 will be placed on the mandrel 1520 first and rolled on and the edge 1630 will self-feather or self-taper. The other sheet 1610 will be then placed on the mandrel and the longest dimension between the end 1612 and the cut line 1630 will be used as the starting point so that the sheet or portion of the sheet 1610 will also self-feather as it is placed upon the previous sheet and the mandrel 1520.
FIG. 18 is a schematic view of one embodiment of a [0067] fixture 1800 for measuring the flexibility of a bat 1810. The fixture 1800 includes a base 1820 which includes an upright 1822 attached to the base and a datum 1824 also attached to the base 1820. The datum 1824 is spaced away from the upright 1822. Attached to the upright 1822 is a load arm 1830. The upright 1822 has an opening 1823 therein. The load arm 1830 is attached to the upright by a pivot pin 1832. The pivot pin 1832 allows the attached end of the load arm 1832 to pivot about the opening 1823 in the upright 1822. A dial indicator 1840 is positioned between the upright 1822 and the datum 1824 and near the load arm 1830. The dial indicator 1840 is placed so that when the bat 1810 is placed in the fixture 1800, the dial indicator 1840 contacts the bat 1810 near the load arm 1830. Positioned at or near the free end of the load arm 1830 is a load cell 1850. The load cell 1850 produces a specified load on the free end of the load arm 1840. The distance between the pivot point at the center of the pivot pin 1832 and the point on the load arm 1830 where the load cell 1850 acts is designated as dimension “A”. The distance between the pivot point at the center of the pivot pin 1832 and the point where the load arm 1830 contacts the bat 1810 is designated as dimension “B”. The distance between the end of the base 1820 nearest the upright 1822 and the datum 1824 is designated as dimension “C”. Of course, different embodiments of the fixture 1800 have different dimensions (A, B, C). In the one embodiment shown in FIG. 18, the dimensions are as follows:
A=17{fraction (9/16)} inches [0068]
B=2¾ inches [0069]
C=4 inches [0070]
In operation, a procedure is set up to test the [0071] bat 1810 for flexibility. The procedure includes placing the bat in the fixture 1800. The bat 1810 is placed on the base 1820 and in contact with datum 1824. Next, the load cell 1850 applies 10 pounds of force at load end or free end of the load arm 1830. The dial indicator 1840 and the load cell 1850 are each zeroed. Next, the load cell 1850 applies 60 pounds of force at load end or free end of the load arm 1830. The dial indicator 1840 is then read to determine the amount of deflection of the bat at the point or in the area where the load arm 1830 contacts the bat 1810. This procedure is repeated a number of times around the circumference of the bat 1810. The average value is then used to determine a number to indicate the flexibility of the bat 1810. One example of a calculation of such a number includes dividing the load placed on the arm by the load cell 1850 by the amount of deflection indicated by the dial indicator 1840. In this example, the load of 60 lbs is divided by the deflection in inches (60 lbs./0.0575″=1043 lbs./in or 1043 Flex) to yield a flex indication number of 1043. It is contemplated that other testers or fixtures could be used to determine flexibility of the bat 1810 under test without departing from the spirit of this invention.
Of course, the amount flexibility of a bat is linked to bat performance. Performance is also determined by the distance a standard ASA softball can be hit as well as the amount of “sting” or vibration within the bat. Using the [0072] fixture 1810 described in the example above bats having a flexibility value in the range of 600 to 1200 have good performance characteristics. Bats having a flexibility in the range of 1000 to 1200 units also have good performance characteristics.
Advantageously, the composite material has a lower density than metals used to make bats, such as aluminum or titanium. As a result, more material can be used resulting in a more durable bat for a given weight of bat. The composites also have a higher strength than aluminum and titanium and their alloys. Therefore, a stronger bat can be produced. In addition, the composite does not dent and therefore more energy is transferred to the ball. There is less, if any, energy wasted on denting the bat or the inner sleeve. Therefore, the inventive bat hits farther than a wooden or metal bat or bat having metal parts. The additional flexibility of the composite material forms a bat with higher performance which hits better. Furthermore, the inventive bat has a durability advantage since the bat does not dent. [0073]
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. [0074]

Claims

What is claimed is:

1. A bat comprising:

a hitting surface;

a handle element attached to the hitting surface;

a first sleeve positioned within the hitting surface; and

a second sleeve positioned within the hitting surface, wherein the hitting surface.

2. The bat of claim 1 wherein the first sleeve and the second sleeve are comprised of composite materials.

3. The bat of claim 2 wherein the hitting surface has a first stiffness and one of the first sleeve and the second sleeve positioned within the hitting surface has a second stiffness different than the first stiffness.

4. The bat of claim 2 wherein the hitting surface is made from a first set of fibers and a first resin and wherein the first sleeve and second sleeve are made from a second set of fibers and a second resin, the second set of fibers and the second resin being different than the first set of fibers and first resin.

5. The bat of claim 4 wherein the second fiber and resin is impregnated in the second set of fibers.

6. The bat of claim 4 wherein the second set of fibers and resin is a sheet of material.

7. The bat of claim 1 wherein the second sleeve is formed on the first sleeve.

8. The bat of claim 1 wherein the first sleeve is separated from the first sleeve by a layer of material.

9. The bat of claim 2 wherein the first sleeve is separated from the second sleeve by a layer of a release material.

10. A bat comprising:

a hitting surface further including;

a first wall;

a second wall; and

a third wall; and

a handle element attached to the hitting surface.

11. The bat of claim 10 wherein the hitting surface is in the shape of a barrel.

12. The bat of claim 10 wherein the first wall is made of a first material and the second wall is made of a second material.

13. The bat of claim 12 wherein the first material is metal.

14. The bat of claim 12 wherein the first material is a composite material.

15. The bat of claim 10 wherein the second wall and the third wall are made of the same materials.

16. The bat of claim 10 wherein the second wall and the third wall are made of different materials.

17. The bat of claim 10 wherein the bat has a flexibility of greater than 600.

18. A bat comprising:

a hitting surface having a flexibility within the range of 600 to 1300; and

a handle attached to the hitting surface.

19. The bat of claim 18 wherein the flexibility is within the range of 800 to 1200.

20. The bat of claim 18 wherein the flexibility is within the range of 950 to 1150.

21. A method of forming a bat having a handle and a hitting surface, the method comprising:

forming a first sleeve;

forming a second sleeve; and

fitting the first sleeve and the second sleeve within the hitting surface.

22. The method of claim 21 wherein the first sleeve is formed of metal.

23. The method of claim 21 wherein the first sleeve and the second sleeve are formed of metal.

24. The method of claim 21 wherein the first sleeve is formed of a composite material.

25. The method of claim 21 wherein the first sleeve and the second sleeve are formed of a composite material.

26. The method of claim 21 wherein the step of forming a first sleeve and a forming a second sleeve further comprises:

laying up a first plurality of layers of material;

covering the first plurality of layers of material with a release material; and

laying up a second plurality of layers of material.

27. The method of claim 26 wherein covering the first plurality of layers with a release material includes covering the first plurality of layers with polypropylene.

28. The method of claim 25 wherein forming a first sleeve includes wrapping a plurality of layers about a mandrel and wherein, forming a second sleeve includes wrapping a plurality of layers about a mandrel.

29. The method of claim 21 further comprising:

loading a portion of the bat; and

measuring the amount of deflection.

30. The method of claim 29 wherein loading a portion of the bat includes placing a force on the hitting surface of the bat.

31. The method of claim 29 wherein loading a portion of the bat includes placing a force on the surface of the bat having a first sleeve and a second sleeve.

32. The method of claim 29 wherein loading a portion of the bat includes placing a force on a plurality of areas associated with the hitting surface of the bat.

33. The method of claim 32 wherein measuring the amount of deflection includes measuring the deflection at the plurality of areas associated with the hitting surface of the bat.

34. The method of claim 32 wherein measuring the amount of deflection includes measuring the deflection at the plurality of areas associated with the hitting surface of the bat, the method further comprising averaging the amount of deflection for each of the measured areas.

35. The method of claim 34 wherein loading the hitting surface at the plurality of areas includes placing substantially the same load on each of the plurality of areas of the hitting surface.

36. The method of claim 32 further comprising dividing the load placed on the bat by the measured deflection to yield a number representing flexibility of the bat.

37. The method of claim 32 further comprising:

dividing the load placed on the bat by the measured deflection to yield a number representing flexibility of the bat;

determining a number representing flexibility at a plurality of points on the bat; and

averaging the determined flexibility numbers.

38. The method of claim 37 wherein the flexibility numbers are determined for a hitting surface of the bat.

39. The method of claim 37 wherein the load placed on the bat is substantially equal at the various portions of the bat.

40. A method of forming a bat having a handle and a hitting surface, the method comprising:

forming a hitting surface; and

forming a plurality of sleeves adjacent the hitting surface.