US 3313541 A
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Description (OCR text may contain errors)
W y 1967 A. J. BENKOCZY ET AL 3313,43
GOLF CLUB INCLUDING REINFORCED FIBER GLASS SHAFT 2 Sheets-Sheet 1 Filed Oct. 11 1963 Fifi-6 INVENTORS w H E C W mu m m T B W A E M C m N E E R R w m Q L April M, 1967 Filed Oct. 11, 1965 LARGER SMALLER FIBERS HBERS HG H 35 LAQQER FIB-c1955 I E w 36 LARGER FIBERS SMALLER HEERS A. J. BENKOCZY ET AL GOLF CLUB INCLUDING REINFORCED FIBER GLASS SHAFT 2 Sheets-Sheet 2 United States Fatent @fifice 3,313,541 Patented Apr. H, 1967 3,313,541 GOLF CLUB INCLUDING REHNFURCED FiBER GLASE SHAFT Andrew J. Beniroczy and Lawrence W. Hull, Miami, Fla, assignors to United States Fiberglass Company, Miami, Fia., a corporation of Florida Filed Get. 11, 1963, Ser. No. 315,497 4 Claims. (Ci. 273-30) This invention relates to a club for playing golf, and particularly to a golf club having a fiberglass shaft.
Previous attempts made to manufacture a golf club having a shaft made of fiberglass material have not been entirely successful for a number of reasons, perhaps the most important of which is that the flexural modulus of the fiberglass is much lower than that of steel so that the clubs are too flexible to meet the rigid professional qualifications. It is possible to increase the flexural modulus by using a. steel tube or reinforcing rod in the shank of the club but this tends to create an unbalanced and expensive club requiring a complex manufacturing process.
Accordingly, an important object of this invention is to provide a fiberglass golf shaft capable of meeting professional flexibility standards while having resistance to torsion, bending and shear loads imparted thereto when the club head strikes a golf ball.
Another object of this invention is to provide a golf club shaft of the character described which is constructed solely of glass fiber material without metal reinforcement, and further to provide a fiberglass golf shaft which has a capability of resisting the complex forces generated at the juncture of the shaft and club head when the latter strikes a golf ball.
A further object of this inventi is to provide a fiberglass golf shaft which is simple and inexpensive thus maintaining the cost thereof at a comparatively low level, and further to provide a golf club shaft which will have the fibers of the fiberglass cloth material arranged in an optimum pattern for maximum strength, stiffness, and dependability throughout its life.
Other objects and advantages of this invention will be apparent from the following description, the accompanying drawings and the appended claims.
In the drawings- FIG. 1 is a perspective view of a golf club using a shaft constructed in accordance with the invention;
FIG. 2 is a plan view of the fiberglass cloth utilized to form the shaft;
FIG. 3 is an elevation view of the mandrel upon which the fiberglass cloth is wrapped to form the shaft;
FIG. 4 is a plan view partially in section of the golf club shaft;
FIG. 5 is an enlarged perspective view of the glass fiber cloth shown in FIG. 2;
FIG. 6 is an enlarged sectional view taken along the line 6-6 of FIG. 4;
FIG. 7 is an enlarged perspective view of another cloth material which can be used to form the golf shaft of FIG. 1;
FIG. 8 is an end view of the shaft shown in FIG. 4;
FIG. 9 is a view of a golf shaft having gradually spiralling longitudinal fibers;
FIG. 10 is an enlarged sectional view similar to FIG. 6 taken along the line 1010 of FIG. 4;
FIG. 11 is another enlarged sectional view taken along the line 1111 of FIG. 4; and
FIG. 12 is an enlarged plan view of the golf club shaft showing the fiber orientation.
An important design consideration in the construction of a fiberglass golf shaft is it low flexural modulus of 6,000,000 as compared to 30,000,000 for steel so that a fiberglass golf club tends to be much too flexible to meet professional standards required for any commercial success. It has been found that an acceptable shaft having a flexural modulus which is sufficiently high to gain approval is attained by arranging the glass fibers parallel to the axis of the shaft. However such a fiber arrangement is susceptible to early failure of the shaft since the complex shear and torsional forces present in such a shaft quickly separate the fibers as the bonding agent is relatively low strength.
This invention solves the problem by using a fiberglass cloth having substantially all of the glass strands running in the warp direction with a minimum number of strands interwoven therewith and running in the fill direction. As will be described, the cloth is formed into a shaft with the warp fibers extending generally parallel to the shaft axis and the fill fibers extending circumferentially thereof to resist torsional forces and separation of the warp fibers.
Referring now to the drawings, wherein a preferred embodiment of the invention is illustrated, FIG. 1 shows a golf club 10 including a shaft 11 having a club head 12 secured to one end thereof and having a handle grip 13 on the opposite end. As indicated above, the invention is particularly directed to the shaft 11 which is constructed of fiberglass cloth, and which is equally adapted for use with both woods and irons.
The sheet 15 of fiberglass cloth is precut to a precise shape to obtain the desired thickness and taper at each point along the length thereof. As seen in FIG. 2, the right hand edge 17 of the sheet 15 is straight and parallel to the warp fibers, and this edge is used to align the sheet during the forming process to insure that the warp fibers will be disposed longitudinally of the mandrel 20. The opposite or left edge 21 has a series of tapered portions thereon which partially define the lower, intermediate and upper sections 22, 23, and 24, respectively, of the sheet 15. The lower section 22 gradually increases in width, and the intermediate section 23 also increases gradually in width although at a slower rate than the lower section 22. The upper section 24 has a gradually decreasing width which creates a relatively thin upper end portion of the shaft, as will be explained.
The mandrel 20 (FIG. 3) has an outer configuration corresponding to the desired inner diameter of the shaft 11 and is used in the formation of the hollow shaft 11 from the sheet 15 of fiberglass cloth described above. Thus, as seen in FIG. 3, the mandrel 20 has a large upper section 26 with a gradual taper, an adjacent intermediate section 27 with a slightly increased taper, and a lower section 28 which has the highest rate of taper. These tapers may be approximately .003, .006, and .012 inch per inch of length, respectively.
The particular configuration of the mandrel 20 and the sheet 15 combine to produce a tubular shaft 11 having a predetermined outer diameter and wall thickness at each point along the length thereof. Thus when the sheet 15 is wrapped onto the mandrel 20, the lower end portion 31 of the shaft 11 has the smallest outside diameter and approximately six layers of wall thickness, the intermediate portion 32 of the shaft has a slightly larger outer diameter with only four layers of material, and the upper portion 33 thereof has the greatest outer diameter with two thicknesses of material. These specific wall thicknesses are set forth for the purposes of explanation only and are not intended as limitative on the scope of the invention. The important point is that the shape of the mandrel 20 and the sheet 15 can be varied in order to construct a tubular shaft 11 of substantially any desired taper, outer diameter, and wall thickness.
A preferred weave of glass fiber cloth illustrated in FIG. 5 is a 12-harness satin weave having warp fibers 35 which are heavier and more dense than the fill fibers 36. Specifically, the cloth has a warp fiber size of 150 1/ 2 with 120 strands per inch and a fill fiber size of 150 l/O with 24 strands per inch. However, other weaves or fiber distributions can be used within the scope of the invention so long as the maximum number of fibers extends parallel to the warp direction.
Thus, as shown in FIG. 7, a sheet a of non-woven cloth material, which includes a plurality of straight strands or warp fibers 37 disposed closely adjacent one another, can be used to form the golf shaft 11. A much smaller number of strands or fill fibers 33 are placed on one side of these in parallel spaced relation to one another and perpendicularly to the strands. Suitable materials of this type are presently sold under the trade name Scotchply by Minnesota Mining and Manufacturing Co., St. Paul, Minn, U.S.A., and BOCS sold by Green Corporation, Livermore, Calif.
In the process for forming the shaft 11, the sheet 15 of fiberglass cloth is first preimpregnated with a high strength thermosetting epoxy resin or the like and allowed to reach the B stage wherein the resin is tacky. Then it is wrapped onto the mandrel with the right edge 17 thereof held parallel to the axis of the mandrel so that the warp fibers 35 are positioned parallel and the fill fibers 36 perpendicular to the axis of the mandrel 20. This cloth-mandrel combination is subsequently wrapped snug ly with cellophane or the like to hold the sheet 15 in place, and prevent the resin from dripping during the curing process.
The curing process involves heating the impregnated cloth to cause polymerization of the resin thus bonding the fibers in the various layers together. The shaft 11 becomes an integral unit with the resin itself offering substantial resistance to the forces imparted to the shaft. The resin preferably has a high heat distortion temperature, good flow and wet-out characteristics so that the curing process produces a dense and homogeneous structure. In addition to epoxy resins a phenolic or polyester resin can be used without departing from the scope of the invention. Moreover, the thermosetting bonding action may be caused by an exothermic reaction, without the application of external heat, caused by the presence of an active catalyst in the resin itself.
A section of the resulting shaft structure is illustrated somewhat schematically in FIG. 6 wherein the fill fibers 36 extend circumferentially around the shaft 11 while being woven between the larger warp fibers 35 which extend generally longitudinally of the shaft 11 for maximum strength and stiffness. The fibers 35 and 36 are held securely in place by the epoxy resin binder 39 which also adds some strength to the shaft 11. It should be understood that the showing of FIG. 6 is not to scale nor is it intended to be an exact sectional view. As a matter of fact, the particular fiber distribution is not entirely visible to the naked eye from a cross-section through the completed shaft since the curing process creates an essentially integral mass from outward appearances.
The process for forming a shaft from the sheet 15a of glass fiber cloth is substantially identical to that described above, with the warp fibers 37 extending generally axially of the shaft and the fill fibers 38 circumferentially thereof. This results in a shaft having a cross-section similar to that shown in FIG. 6, with the fill fibers between the layers of but not interwoven with the warp fibers.
It is also within the scope of the invention to Wrap the cloth 15 or 15a on the mandrel 20 in such a manner that the warp fibers 35 or 37 have a gradual spiral from one end of the shaft to the other, as seen in FIG. 9. A certain amount of spiral will be created in any case by tapered mandrel 20, but by Wrapping the tapered edge 21 onto the mandrel first, a slightly more pronounced spiral will be introduced into the shaft. This spiral preferably extends downwardly in a direction opposing the direction of torque applied to the shaft when the head 12 strikes a golf ball, to wit, in a right-handed club the taper would be in a downward counterclockwise direction from the grip 13 toward the club 12 whereas in a lefthanded club it would be downwardly in a clockwise direction. However, it is within the scope of this invention to create this spiral in either direction for either type of club.
The lower end 34 of the portion 31 of the shaft is connected to the club head 12, and is subjected to high torsional and shear forces and therefore is constructed with a substantial wall thickness as compared to the grip end of the shaft 11. To increase the strength of the shaft in this area, a generally triangular patch 40 of the fiberglass cloth is placed on the lower section 22 of the sheet 15 and rolled therewith onto the mandrel 20. The warp fibers of this patch extend at an angle a to those of the sheet 15, preferably between 30 and thereto, so that the warp fibers therein aid in resisting the high torsional and shear forces in this area of the shaft. The patch preferably adds several layers to the lower portion 331 of the shaft 11, and its exact size, thickness, and weave configuration can be varied within the scope of the invention so long as the axis of a substantial portion of the fibers thereof are disposed at an angle to the warp fibers of the sheet 15.
The particular thickness of the finished shaft 11 at any point along its length can be varied without departing from the scope of this invention by charging the configuration of the sheet of glass fiber material, by varying the size of the mandrel, or by a combination of these changes. For example, .by increasing the width of the lower section 22 of the sheet 15 the thickness of the lower portion 31 of the shaft 11 will be proportionately increased.
Thus the invention has provided a fiberglass golf shaft which has sufiicient rigidity to comply with the rigid professional standards, and which also has the increased strength and corrosion resistant features of fiberglass. Variation in balance, weight distribution and flexural characteristics of the shaft 11 can be achieved according to predetermined standards heretofore followed for steel and other conventional golf shafts. The invention is easily adaptable to provide a shaft for golf clubs of different sizes and strength as required in making short and long irons, and woods, as well as increasingly smaller clubs for use by women and children. Moreover, the shaft does not require metal reinforcing elements which would tend to unbalance the golf club and increase the cost thereof.
While the article herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise article, and that changes may be made therein Without departing from the scope of the invention which is defined in the appended claims.
What is claimed is:
1. A golf club including a tapered shaft having a club head secured to the smaller end thereof and a hand grip secured to the larger end thereof, said shaft consisting essentially of a plurality of parallel longitudinal glass fibers in said shaft each extending substantially axially of said shaft from said grip to said head, a plurality of parallel and generally circumferentially disposed glass fibers interwoven with indivdual small groups of said longitudinal fibers to increase the hoop strength along the entire length of the shaft and provide resistance against collapsing of said tubular shaft when the club head strikes a golf ball, said circumferential fibers being substantially fewer in number than said longitudinal fibers for maximum longitudinal stiffness, said longitudinal and circumferential glass fibers being disposed in a plurality of layers, said plurality of layers varying in number along the length of said tubular shaft so that the wall thickness of said shaft varies along its length with the greatest thickness being disposed at said smaller end for maximum strength in the portion of the shaft adapted to support the club head, a plurality of reinforc ing glass fibers disposed in said smaller end between said layers and at an angle of about 30-45" to said longitudinal fibers to resist torsional stresses which are the greatest at said end when the club head strikes a golf ball, and thermosetting resin binder means for joining said fibers and said layers together in a substantially integral tube capable of resisting the torsional, inter-laminar shear and other forces imposed thereon,
2. A golf club shaft as defined in claim 1 wherein said circumferential fibers are smaller in diameter than said longitudinal fibers.
3. A golf club shaft as defined in claim 1 wherein said longitudinal fibers spiral gradually downward in a direction opposite to the direction of the torsional forces imparted to said shaft when the club head strikes a golf ball.
4. A golf club shaft as defined in claim 1 wherein said plurality of layers includes two layers at said larger end and six layers at said smaller end.
References (Jited by the Examiner UNITED STATES PATENTS 1,662,712 3/1928 Mensing 27380 2,573,361 10/1951 Rodgers et a1. 27380 X 2,643,700 6/1953 Havens.
2,726,185 12/1955 HOWaId.
2,747,876 5/ 1956 Teller.
2,760,896 8/1956 Nash 156-184 2,809,144 10/1957 Grimes 156192 2,934,345 4/1960 Scott 27380 2,991,080 7/1961 Redmond 273-80 3,166,319 1/1965 Brilhart.
RICHARD C. PINKHAM, Primary Examiner.
G. J. MARLO, Assistant Examiner.