Title:
METHOD OF MAKING A HOLLOW METAL BAT WITH A UNIFORM WALL THICKNESS
United States Patent 3854316
Abstract:
A method of making a hollow metal ball bat having a wall thickness along the length thereof that is substantially uniform thereby providing a weight ratio for the handle and barrel portions of the bat that approximates the diameters of the handle and barrel portions. The handle portion of the bat is formed by a swaging process which reduces the diameter of a portion of a metal tube blank, having generally a uniform diameter and wall thickness, on a mandrel having a substantially uniform diameter. The mandrel is effective to maintain the uniform wall thickness of the blank by forcing the metal thereof to flow longitudinally from the end of the blank forming the handle portion of the bat.
US Patent References:
Baseball bat
Shroyer, Jr. - June 1924 - 1499128
Tube swaging machine and method
Muller - August 1931 - 1819376
Apparatus for cold-reducing tubular metal stock
Richards - November 1952 - 2617319
METHOD OF MAKING BALL BAT METAL BODY SYSTEM
Swenck - September 1972 - 3691625
BALL BAT WITH ECCENTRICALLY THICKENED WALLS
Merola - October 1972 - 3697069
Baseball bat
Shroyer, Jr. - June 1924 - 1499128
Tube swaging machine and method
Muller - August 1931 - 1819376
Apparatus for cold-reducing tubular metal stock
Richards - November 1952 - 2617319
METHOD OF MAKING BALL BAT METAL BODY SYSTEM
Swenck - September 1972 - 3691625
BALL BAT WITH ECCENTRICALLY THICKENED WALLS
Merola - October 1972 - 3697069
Application Number:
05/325423
Publication Date:
12/17/1974
Filing Date:
01/22/1973
View Patent Images:
Export Citation:
Assignee:
Aluminum Company of America (Pittsburgh, PA)
Primary Class:
Other Classes:
72/370.140, 473/566, 72/76
International Classes:
B21K17/00; B21K21/00; B21K17/00
Field of Search:
72/76,370,402 273/72A
Primary Examiner:
Larson, Lowell A.
Attorney, Agent or Firm:
Strickland, Elroy
Parent Case Data:
This is a division of application Ser. No. 179,666, filed Sept. 13, 1971.
Claims:
Having thus described my invention and certain embodiments thereof, I claim
1. A method of making a hollow metal bat having a non-uniform weight per unit length characteristic, said bat comprising an elongated hollow metal body having a cylindrical barrel portion of one diameter tapering through a transition portion to a cylindrical handle portion of reduced diameter, the method comprising the steps of
2. The method of claim 1 in which the metal of the hollow tube is reduced in diameter in an annealed condition followed by heat treating and aging to provide the metal with a T6 temper.
1. A method of making a hollow metal bat having a non-uniform weight per unit length characteristic, said bat comprising an elongated hollow metal body having a cylindrical barrel portion of one diameter tapering through a transition portion to a cylindrical handle portion of reduced diameter, the method comprising the steps of
2. The method of claim 1 in which the metal of the hollow tube is reduced in diameter in an annealed condition followed by heat treating and aging to provide the metal with a T6 temper.
Description:
BACKGROUND OF THE INVENTION
The present invention relates generally to hollow, metal ball bats, and particularly to a high strength, hollow metal bat having a weight distribution approximating that of a solid wooden baseball bat.
In the manufacture of metal ball bats, the practice has been, in some instances, to provide the bats with weights in the barrel (i.e., the ball striking end of the bat) in order to enhance the effectiveness of the bat, and to simulate the weight distribution of a solid wooden bat. Examples of such structures are shown in the Shroyer, Jr. and Middlekauff U.S. Pat. Nos. 1,499,128 and 1,611,858 respectively.
On the other hand, hollow metal bats have been made with a substantially uniform weight per unit length of the bat, for example, as shown in the Merola U.S. Pat. No. 3,479,030. In the Merola patent, this is accomplished by reducing the diameter of a portion of a metal tube blank in a swaging operation to form the handle portion of the bat, the blank having a substantially uniform starting diameter and wall thickness. As the blank is reduced in diameter, a substantially thickened metal wall is produced in the thus formed handle portion which maintains the above-mentioned uniform weight per unit length characteristic.
Hollow metal bats have been strengthened in a variety of ways. In the above-mentioned Middlekauff patent, an inner sleeve is secured in the barrel end of the bat along with a weighted insert which closes the end of the bat. In a Taylor et al. U.S. Pat. No., 2,340,156, integral, longitudinally extending ribs are employed on the inside wall surface of a bat to strengthen the bat.
By virtue of the additional metal and materials of the weights, sleeves and ribs as well as the labor and machines involved in making and assembling such structures of the above, prior art bats, unnecessary costs are added to the bats. In view of such structures, a hollow metal bat is needed having a weight distribution that is inherently non-uniform and corresponding to that of a wooden bat without the necessity of adding weights to the barrel end thereof to obtain such a weight distribution. Further, a hollow metal bat is needed which has a high strength, long life characteristic without the necessity of reinforcing cylinders or integral, internal ribs.
BRIEF SUMMARY OF THE INVENTION
The present invention provides such a bat, and a simple, economical method of making the bat. The desired, non-uniform weight distribution characteristic of the bat is provided by establishing a wall thickness for the handle portion thereof that is substantially the same as the wall thickness of the barrel portion of the bat. In this manner, the weight ratio of the handle and barrel portions approximates the ratio of the outer or inner diameters of handle and barrel portions thereby providing the bat with a balance approximating that of a wooden bat without the necesssity of adding weights to the barrel end of the bat.
An additional advantage of such a bat structure is the savings in metal. The reduced outer and inner diameters of the handle do not reduce the strength of the handle beyond that required for the bat. Thus, any increase in the thickness of the handle wall portion beyond that thickness required for suitable handle strength is wasted metal which adds unnecessarily to the cost of the bat.
The bat of the present invention is made by swaging the outer and inner diameters of an end portion of a metal tube blank on a constant diameter mandrel, the blank having originally a substantially uniform diameter and wall thickness and the mandrel serving to control the flow of metal during the swaging action in such a manner that the wall thickness of the swaged, i.e., reduced portion of the blank is maintained at substantially its original uniform wall thickness.
The 7XXX series of aluminum alloys have been found to be suitable for the invention though the invention is not limited thereto. After the blank is swaged, it is tempered to provide a high strength, stress corrosion resistant metal for long bat life as explained in greater detail hereinafter.
The Drawing
The invention, along with its advantages and objectives, will be more apparent after consideration of the following detailed description in connection with the accompanying drawing in which FIGS. 1 and 2 show longitudinal sections of a bat constructed in accordance with the principles of the present invention.
Preferred Embodiment of the Invention
In reference to the drawing, FIG. 1 shows the bat of the invention in longitudinal section to depict the wall thickness of the bat. More particularly, the bat comprises a barrel portion 10 and a handle or grip portion 12, the wall thicknesses of the two portions being substantially the same to provide a weight distribution for the bat that is non-uniform along its length. By virtue of the same or similar wall thicknesses of the barrel and handle portions, and the differences in the diameters of the two portions, the ratio of the weights of the two portions approximates the ratio of the outer or inner diameters of the two portions, and thus the weight distribution of a solid wooden baseball bat. Extending between and joining the two portions is a transition portion 13.
In order not to affect substantially the weight distribution of the finished bat, the open ends thereof (as shown in the drawing) are preferably closed respectively with plugs 14 and 16 (shown in dash outline) made of a light weight, shock resistant material such as a natural or synthetic rubber, or a polyvinyl chloride plastic, though other light weight, shock resistant materials and material combinations may be used. The plug 14 in the barrel end of the bat may be secured therein by the extremity of the barrel end being turned inwardly to engage the plug as shown in the drawing. The plug 16 in the handle end of the bat may include an integral sleeve 17 slipped over the handle portion (as shown) to provide a hand gripping area of rubber for the bat.
The bat, as thus far described, is made from a single piece metal tube blank (not shown) preferably extruded or drawn to have a substantially uniform diameter and wall thickness. One end of the blank will form the barrel and ball striking end 10 of the bat, and the other end of the blank will form the handle and grip portion 12 of the bat.
In making the bat, the end 12 of the tube blank that will form the handle and the tapered portions 12 and 13 is inserted between conical dies of a swaging machine (not shown), the end portion 12 extending over a fixed mandrel 18 (FIG. 2) located between a portion of the dies in the back of the machine. As shown, the mandrel has a substantially constant diameter. The dies of the machine are operated to perform a swaging action on the portions of the blank inserted therein, the dies reducing the diameter of the end portion 12 on the fixed mandrel, the diameter reducing process tapering the transition portion 13 of the bat, which is free of the mandrel. As the metal of the blank is moved inwardly by the conical dies it naturally increases in wall thickness in inverse proportion to its new diameter. When the inside diameter reaches the diameter of the fixed mandrel 18 it cannot be reduced further. The outside diameter is further reduced by the conical dies and the metal is thinned along the handle portion 12. As this thinning occurs, the length of the handle increases toward the free and open end of the handle 12. At the end of the swaging process, the thickness of the handle and tapered portion of the bat are substantially the same as that of the barrel portion.
As can be appreciated, the use of a mandrel in the swaging, diameter reducing process functions to keep the metal of the tube blank from thickening in the handle portion 12. In this manner, the wall thickness of the handle portion is maintained at substantially the same thickness of the original blank and thus essentially the same thickness of the barrel portion 10 which does not undergo a reduction in diameter. With the reduction in diameter of the handle portion without a corresponding increase in wall thickness thereof, the weight per unit length of handle portion is substantially less than that of the barrel portion thereby approximating the weight distribution of a wooden bat.
For example, in one softball bat embodiment of the invention, the weight per unit of length of the handle portion, using 1 inch sections actually cut therefrom as the unit of length, averaged about 0.59 of an ounce in comparison to an average weight of 0.91 of an ounce for 1 inch sections cut from the barrel of the same bat.
In a hardball bat of the invention suitable for youth league play, 1 inch sections of the handle 12 averaged 0.51 of an ounce while the barrel 10 averaged 1.03 ounces per inch. A regular hardball bat of the invention weighs 0.56 of an ounce per inch of handle length, and 1.32 ounces per inch of barrel length. As can be appreciated from these figures, the process of reducing the handle portion on a mandrel produced a bat having a barrel portion substantially heavier than the handle portion.
Suitable metals for the swaging and tapering process are those of the 7XXX aluminum alloy series, the metals being annealed to facilitate the working of the metal in the swaging process.
After the swaging process or before the swaging process depending in a large degree upon the metal and alloys employed, the metal of the bat is tempered preferably by the heat treating and age hardening (T6) process described in the Vernam et al. U.S. Pat. No. 3,171,760. In the process of swaging, the metal of the bat is subjected to stresses which tend to weaken the metal. With subsequent stresses imposed on the bat via the normal use thereof, cracks can occur in the weakened areas of the bat which, in turn, allow corrosion to occur in the cracks thereby causing further weakening and deterioration of the metal. By the solution heat treating and age hardening (T6) process described in the Vernam et al. patent, the metal of the swaged bat is hardened and made resistant to stress corrosion cracking thereby providing a long-life, dent-resistant bat without the need of further strengthening devices. Though the T6 temper is preferred for the bat of the invention, a T53 temper would suffice.
Wall thickness dimensions for the bat of the invention made from 7005 or 7075 aluminum alloys are preferably in the range of 0.080 to 0.130 of an inch for outside diameter barrels ranging from 2 to 23/4 inches.
From the foregoing description it should now be apparent that a new and useful ball bat having a weight distribution substantially the same as a wooden bat has been disclosed along with a novel method of making the bat. The bat, and the method of making it, result in considerable savings in metal, and thus savings in the cost of the bat as well as effecting the weight distribution without the use of weights added to the barrel end of the bat.
While the invention has been described in terms of preferred embodiments, the claims appended hereto are intended to encompass all embodiments which fall within the spirit of the invention.
The present invention relates generally to hollow, metal ball bats, and particularly to a high strength, hollow metal bat having a weight distribution approximating that of a solid wooden baseball bat.
In the manufacture of metal ball bats, the practice has been, in some instances, to provide the bats with weights in the barrel (i.e., the ball striking end of the bat) in order to enhance the effectiveness of the bat, and to simulate the weight distribution of a solid wooden bat. Examples of such structures are shown in the Shroyer, Jr. and Middlekauff U.S. Pat. Nos. 1,499,128 and 1,611,858 respectively.
On the other hand, hollow metal bats have been made with a substantially uniform weight per unit length of the bat, for example, as shown in the Merola U.S. Pat. No. 3,479,030. In the Merola patent, this is accomplished by reducing the diameter of a portion of a metal tube blank in a swaging operation to form the handle portion of the bat, the blank having a substantially uniform starting diameter and wall thickness. As the blank is reduced in diameter, a substantially thickened metal wall is produced in the thus formed handle portion which maintains the above-mentioned uniform weight per unit length characteristic.
Hollow metal bats have been strengthened in a variety of ways. In the above-mentioned Middlekauff patent, an inner sleeve is secured in the barrel end of the bat along with a weighted insert which closes the end of the bat. In a Taylor et al. U.S. Pat. No., 2,340,156, integral, longitudinally extending ribs are employed on the inside wall surface of a bat to strengthen the bat.
By virtue of the additional metal and materials of the weights, sleeves and ribs as well as the labor and machines involved in making and assembling such structures of the above, prior art bats, unnecessary costs are added to the bats. In view of such structures, a hollow metal bat is needed having a weight distribution that is inherently non-uniform and corresponding to that of a wooden bat without the necessity of adding weights to the barrel end thereof to obtain such a weight distribution. Further, a hollow metal bat is needed which has a high strength, long life characteristic without the necessity of reinforcing cylinders or integral, internal ribs.
BRIEF SUMMARY OF THE INVENTION
The present invention provides such a bat, and a simple, economical method of making the bat. The desired, non-uniform weight distribution characteristic of the bat is provided by establishing a wall thickness for the handle portion thereof that is substantially the same as the wall thickness of the barrel portion of the bat. In this manner, the weight ratio of the handle and barrel portions approximates the ratio of the outer or inner diameters of handle and barrel portions thereby providing the bat with a balance approximating that of a wooden bat without the necesssity of adding weights to the barrel end of the bat.
An additional advantage of such a bat structure is the savings in metal. The reduced outer and inner diameters of the handle do not reduce the strength of the handle beyond that required for the bat. Thus, any increase in the thickness of the handle wall portion beyond that thickness required for suitable handle strength is wasted metal which adds unnecessarily to the cost of the bat.
The bat of the present invention is made by swaging the outer and inner diameters of an end portion of a metal tube blank on a constant diameter mandrel, the blank having originally a substantially uniform diameter and wall thickness and the mandrel serving to control the flow of metal during the swaging action in such a manner that the wall thickness of the swaged, i.e., reduced portion of the blank is maintained at substantially its original uniform wall thickness.
The 7XXX series of aluminum alloys have been found to be suitable for the invention though the invention is not limited thereto. After the blank is swaged, it is tempered to provide a high strength, stress corrosion resistant metal for long bat life as explained in greater detail hereinafter.
The Drawing
The invention, along with its advantages and objectives, will be more apparent after consideration of the following detailed description in connection with the accompanying drawing in which FIGS. 1 and 2 show longitudinal sections of a bat constructed in accordance with the principles of the present invention.
Preferred Embodiment of the Invention
In reference to the drawing, FIG. 1 shows the bat of the invention in longitudinal section to depict the wall thickness of the bat. More particularly, the bat comprises a barrel portion 10 and a handle or grip portion 12, the wall thicknesses of the two portions being substantially the same to provide a weight distribution for the bat that is non-uniform along its length. By virtue of the same or similar wall thicknesses of the barrel and handle portions, and the differences in the diameters of the two portions, the ratio of the weights of the two portions approximates the ratio of the outer or inner diameters of the two portions, and thus the weight distribution of a solid wooden baseball bat. Extending between and joining the two portions is a transition portion 13.
In order not to affect substantially the weight distribution of the finished bat, the open ends thereof (as shown in the drawing) are preferably closed respectively with plugs 14 and 16 (shown in dash outline) made of a light weight, shock resistant material such as a natural or synthetic rubber, or a polyvinyl chloride plastic, though other light weight, shock resistant materials and material combinations may be used. The plug 14 in the barrel end of the bat may be secured therein by the extremity of the barrel end being turned inwardly to engage the plug as shown in the drawing. The plug 16 in the handle end of the bat may include an integral sleeve 17 slipped over the handle portion (as shown) to provide a hand gripping area of rubber for the bat.
The bat, as thus far described, is made from a single piece metal tube blank (not shown) preferably extruded or drawn to have a substantially uniform diameter and wall thickness. One end of the blank will form the barrel and ball striking end 10 of the bat, and the other end of the blank will form the handle and grip portion 12 of the bat.
In making the bat, the end 12 of the tube blank that will form the handle and the tapered portions 12 and 13 is inserted between conical dies of a swaging machine (not shown), the end portion 12 extending over a fixed mandrel 18 (FIG. 2) located between a portion of the dies in the back of the machine. As shown, the mandrel has a substantially constant diameter. The dies of the machine are operated to perform a swaging action on the portions of the blank inserted therein, the dies reducing the diameter of the end portion 12 on the fixed mandrel, the diameter reducing process tapering the transition portion 13 of the bat, which is free of the mandrel. As the metal of the blank is moved inwardly by the conical dies it naturally increases in wall thickness in inverse proportion to its new diameter. When the inside diameter reaches the diameter of the fixed mandrel 18 it cannot be reduced further. The outside diameter is further reduced by the conical dies and the metal is thinned along the handle portion 12. As this thinning occurs, the length of the handle increases toward the free and open end of the handle 12. At the end of the swaging process, the thickness of the handle and tapered portion of the bat are substantially the same as that of the barrel portion.
As can be appreciated, the use of a mandrel in the swaging, diameter reducing process functions to keep the metal of the tube blank from thickening in the handle portion 12. In this manner, the wall thickness of the handle portion is maintained at substantially the same thickness of the original blank and thus essentially the same thickness of the barrel portion 10 which does not undergo a reduction in diameter. With the reduction in diameter of the handle portion without a corresponding increase in wall thickness thereof, the weight per unit length of handle portion is substantially less than that of the barrel portion thereby approximating the weight distribution of a wooden bat.
For example, in one softball bat embodiment of the invention, the weight per unit of length of the handle portion, using 1 inch sections actually cut therefrom as the unit of length, averaged about 0.59 of an ounce in comparison to an average weight of 0.91 of an ounce for 1 inch sections cut from the barrel of the same bat.
In a hardball bat of the invention suitable for youth league play, 1 inch sections of the handle 12 averaged 0.51 of an ounce while the barrel 10 averaged 1.03 ounces per inch. A regular hardball bat of the invention weighs 0.56 of an ounce per inch of handle length, and 1.32 ounces per inch of barrel length. As can be appreciated from these figures, the process of reducing the handle portion on a mandrel produced a bat having a barrel portion substantially heavier than the handle portion.
Suitable metals for the swaging and tapering process are those of the 7XXX aluminum alloy series, the metals being annealed to facilitate the working of the metal in the swaging process.
After the swaging process or before the swaging process depending in a large degree upon the metal and alloys employed, the metal of the bat is tempered preferably by the heat treating and age hardening (T6) process described in the Vernam et al. U.S. Pat. No. 3,171,760. In the process of swaging, the metal of the bat is subjected to stresses which tend to weaken the metal. With subsequent stresses imposed on the bat via the normal use thereof, cracks can occur in the weakened areas of the bat which, in turn, allow corrosion to occur in the cracks thereby causing further weakening and deterioration of the metal. By the solution heat treating and age hardening (T6) process described in the Vernam et al. patent, the metal of the swaged bat is hardened and made resistant to stress corrosion cracking thereby providing a long-life, dent-resistant bat without the need of further strengthening devices. Though the T6 temper is preferred for the bat of the invention, a T53 temper would suffice.
Wall thickness dimensions for the bat of the invention made from 7005 or 7075 aluminum alloys are preferably in the range of 0.080 to 0.130 of an inch for outside diameter barrels ranging from 2 to 23/4 inches.
From the foregoing description it should now be apparent that a new and useful ball bat having a weight distribution substantially the same as a wooden bat has been disclosed along with a novel method of making the bat. The bat, and the method of making it, result in considerable savings in metal, and thus savings in the cost of the bat as well as effecting the weight distribution without the use of weights added to the barrel end of the bat.
While the invention has been described in terms of preferred embodiments, the claims appended hereto are intended to encompass all embodiments which fall within the spirit of the invention.