Patent Application
20090143163
This application claims priority on Patent Application No. 2007-313418 filed in JAPAN on Dec. 4, 2007, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a golf club and a grip for the golf club.
2. Description of the Related Art
A grip is attached to a golf club. In a swing, the grip is worn out. In order to suppress the wear, it is preferable that a material of the grip should be hardened. In the case in which the material of the grip is hardened, however, a grip feeling (a grip comfort) is apt to be deteriorated. In the case in which the material of the grip is hardened, a coefficient of friction is apt to be reduced. A grip having a low coefficient of friction is slippery. In the case in which sweat or rainwater sticks to a surface of the grip, particularly, the grip is slippery. It has been desired to obtain a grip which has a good grip feeling and is hard to slip.
Japanese Laid-Open Patent Publication No. 6-15019 has disclosed a grip for a golf club in which a recess portion for absorbing sweat is formed on a surface of the grip and has disclosed a cut and a groove having a very small width as the recess portion for absorbing sweat.
A pressing force and a twisting force act on a grip during a swing. A portion divided by a cut or a groove having a very small width (which will be hereinafter referred to as a block) might be caused to fall down by the forces. In the grip disclosed in the document, it has been found that the fall-down of the block is apt to be generated. Due to the fall-down, the grip might be excessively deformed during the swing. Due to the deformation of the grip which is caused by the fall-down, furthermore, a shaft axis might excessively fluctuate with respect to a grip axis, resulting in an unstable behavior of a club. The instability of the behavior of the club might also have a bad influence on a stability of the swing. Moreover, it has been found that a partial wear of the grip is apt to be caused by the fall-down.
It is an object of the present invention to provide a golf club which is hard to slip in wetting and can enhance a stability of a swing.
A golf club according to the present invention includes a head, a shaft and a grip. At least one siping groove is provided on a surface of the grip. The siping groove is bent in a direction of a depth of the grip. A width of the siping groove is set to be equal to or greater than 0.15 mm and is equal to or smaller than 1.5 mm.
It is preferable that an opening edge of the siping groove should be bent.
In a grip for a golf club according to the present invention, at least one siping groove is provided on a surface of the grip. The siping groove is bent in a direction of a depth of the grip. A width of the siping groove is set to be equal to or greater than 0.15 mm and is equal to or smaller than 1.5 mm in a state in which the grip is attached to a shaft.
By the siping groove bent in the direction of the depth, it is possible to suppress fall-down, thereby enhancing a stability of a swing. By the siping groove, moreover, it is possible to enhance a slipping difficulty in wetting.
The present invention will be described below in detail based on a preferred embodiment with reference to the drawings.
As shown in
The head 4 is not restricted. Examples of the head 4 include a head of a wood type, a head of an iron type, and a putter head. The shaft 6 is not restricted. Examples of the shaft 6 include a so-called steel shaft and a so-called carbon shaft.
In
The shaft 6 is cylindrical, which is not shown. The grip 8 is cylindrical, which is not shown. The surface 8a of the grip 8 is a curved surface taking an almost circular shape. The grip 8 has a so-called back line, which is not shown. Therefore, a sectional shape of the surface 8a is not a complete round. The sectional shape of the surface 8a is almost circular.
As shown in
The siping groove g1 is provided over a whole part in a circumferential direction of the grip 8, which is not shown. Moreover, the siping groove g1 is provided on a part in the longitudinal direction of the grip 8. In other words, the siping groove g1 is not provided in a tip portion of the grip 8.
In
The width Wg is measured in a state in which the grip 8 is attached to the shaft 6. In some cases, the grip 8 is extended in the circumferential direction through an insertion of the shaft 6. In some cases, therefore, the width Wg is greater than a groove width in the case in which the grip 8 is single. In some cases, the groove width in the case in which the grip 8 is single is 0.0 mm and the width Wg is equal to or greater than 0.15 mm.
The opening edge e1 is bent. The opening edge e1 is bent zigzag. A plurality of siping grooves g1 taking the same shape may be provided on the grip 8. The opening edge e1 is extended in the longitudinal direction of the grip 8 with a reciprocation in the circumferential direction of the grip 8. An interval between the adjacent siping grooves g1 is set to be constant. The adjacent opening edges e1 are parallel with each other. The opening edge e1 is bent almost periodically. The opening edge e1 may be bent aperiodically. The opening edge e1 may be bent randomly. The interval between the adjacent siping grooves g1 does not need to be constant.
In the present invention, a bending specification of the opening edge e1 is not restricted. The opening edge e1 may be bent as in the present embodiment or may be a smooth curve. For example, the opening edge e1 may be bent in a wavy shape. Moreover, it is sufficient that the opening edge e1 in the groove g1 is bent in at least one portion. In the present invention, it is also possible to mix a siping groove having the opening edge e1 which is bent and a siping groove having the opening edge e1 which is not bent.
As shown in
Thus, the siping groove g1 is bent in the depth direction. The siping groove g1 is bent in the depth direction. A plurality of siping grooves g1 having the same shape is provided on the grip 8. All of the siping grooves g1 are the same as in the grip. A siping groove g1 having a different specification may be provided.
In the present invention, a bending specification in the depth direction is not restricted. In the depth direction, the siping groove g1 may be bent or may be a smooth curve. For example, the siping groove g1 may be bent in a wavy shape in the depth direction. In the depth direction, moreover, it is sufficient that the siping groove g1 is bent in at least one portion. In the present invention, it is also possible to provide a groove which is not bent in the depth direction together with the siping groove g1.
A material of the grip is not restricted but a rubber composition and a resin composition are taken as an example. For a rubber in the rubber composition, it is possible to use a natural rubber (NR), an ethylene propylene diene rubber (EPDM), a styrene butadiene rubber (SBR), an isoprene rubber (IR), a butadiene rubber (BR), a chloroprene rubber (CR), an acrylonitrile butadiene rubber (NBR) and the like. In particular, it is preferable to use the natural rubber or a rubber obtained by blending, with the natural rubber, the ethylene propylene diene rubber or the styrene butadiene rubber which has a high affinity to the natural rubber or the like.
Oil may be blended with the rubber composition. It is possible to use aromatic oil, naphthenic oil, paraffinic oil or the like for the oil, for example.
In addition to the rubber, sulfur and the oil, a reinforcing agent, a filler, a vulcanization accelerator, a vulcanization assistant or the like may be properly blended with the rubber composition of the grip if necessary, for example. Furthermore, an anti-aging agent, a processing aid or the like may be blended.
For example, carbon, silica or the like can be used as the reinforcing agent. For example, hard clay, calcium carbonate, magnesium carbonate, clay or the like is used as the filler. For example, zinc oxide, stearic acid or the like is used for the vulcanization assistant. The vulcanization accelerator can be properly selected corresponding to a used rubber in accordance with a well-known method.
A resin composition can also be used for the material of the grip. Examples of a resin contained in the resin composition include a thermoplastic resin. The thermoplastic resin can be used for injection molding. For the thermoplastic resin, a thermoplastic elastomer is preferable and a thermoplastic elastomer containing a soft segment and a hard segment is more preferable. In respect of a consistency of a gripping property with an abrasion resistance, a thermoplastic polyurethane elastomer is more preferable.
A preferable blending ratio to 100 parts by weight of a rubber is obtained by 5 to 70 parts by weight of the reinforcing agent, 10 to 70 parts by weight of the filler, 0.1 to 3 parts by weight of the vulcanization accelerator, and 1 to 10 parts by weight of the vulcanization assistant. The ratio is not restricted.
A method of manufacturing the grip 8 is not restricted. The grip 8 can be manufactured by a well-known manufacturing method. Examples of the manufacturing method include press molding and injection molding.
In the press molding, a rubber composition is filled in a mold and a pressurization and heating are carried out. A heating temperature is usually set to be 130 to 200° C. and is not restricted thereto. A heating time is usually set to be 3 to 15 minutes and is not restricted thereto.
Description will be given to an example of a manufacturing method using the press mold 10. First of all, a rubber composition processed like a sheet is cut into a strap so that a rubber sheet for the lower mold half is obtained. The rubber sheet for the lower mold half is disposed on the internal mold surface m1 of the lower mold half 12. Next, the tip member, the rear end member and the core mold 14 are attached to the lower mold half 12. The tip member is attached to the tip portion of the internal mold surface m1. The rear end member is attached to the rear end of the internal mold surface m1. A tip of the core mold 14 is attached to the tip member. A rear end of the core mold 14 is attached to the rear end member. The core mold 14 thus attached is fixed with a clearance formed between the core mold 14 and the internal core surface m1. Then, a rubber sheet for the upper mold half is disposed on an upper side of the core mold 14. The rubber sheet for the upper mold half is the same as the rubber sheet for the lower mold half. Then, the upper mold half and the lower mold half 12 are brought face to face with each other so that the press mold 10 is closed. After the heating and the pressurization are ended, the press mold 10 is opened to take a molded product out. The core mold 14 is pulled out of the molded product so that the grip 8 is obtained. Although the rubber sheet for the upper mold half and the rubber sheet for the lower mold half are used for the materials to be filled in the press mold 10 in the manufacturing method, the materials to be filled may be wound around the core mold 14 in place thereof.
The lower mold half 18 and the upper mold half have a material injecting path 22. The material is injected from the material injecting path 22 into the mold.
As an example of a manufacturing method using the injection mold 16, the injection mold 16 is first closed and the material is then injected from the material injecting path 22. A structure of the closed injection mold 16 is the same as a structure of the press mold 10. Thereafter, a molded product is taken out. For the injection mold, it is also possible to use a mold which is not divided vertically in addition to the mold 16 shown in
The projecting portion t1 may be formed integrally with a mold body h1. Examples of the integral forming method include a method of casting a mold by a lost-wax process. In the case in which a large number of projecting portions t1 are provided, a great deal of time and labor is required for the integral molding.
In the present embodiment, a groove molding body s1 for forming the projecting portion t1 is used. The groove molding body s1 is formed separately from the mold body h1. The mold body h1 has an inserting groove v1 for inserting the groove molding body s1. The groove molding body s1 is inserted into the inserting groove v1 and is thus fixed to the mold body h1.
The groove molding body s1 takes a shape obtained by bending a thin plate. The groove molding body s1 can be fabricated by forging, casting or the like. In case of the groove molding body s1 taking a complicated shape, particularly, it is preferable that the groove molding body s1 should be cast. In respect of easiness of a processing into a complicated shape, a metal is preferable for the material of the groove molding body s1, and particularly, an aluminum alloy is more preferable. Moreover, one siping groove g1 may be formed by one groove molding body s1 or may be formed by a plurality of groove molding bodies s1.
The shape of the groove molding body s1 corresponds to the shape of the siping groove g1. A sectional shape of the groove molding body s1 is bent in the direction of the depth of the grip. As a groove molding body s1 according to another embodiment, a groove molding body s1 taking the Miura folding shape is taken. The Miura folding is obtained by combining parallelogram planes. The Miura folding is constituted by parallelograms divided by angular projection folding and angular recess folding. The parallelograms are congruent with each other. The Miura folding can fold a plane three-dimensionally without generating wrinkles of a strain. Accordingly, the groove molding body s1 taking the Miura folding can easily be formed. The Miura folding was invented by Professor Miura in The Institute of Space and Astronautical Science.
Water or sweat sticking to the surface of the grip 8 can enter an inner part of the sipping groove g1. Consequently, the water or sweat present on the surface of the grip 8 can be absorbed into the grip 8. By the siping groove g1, it is possible to enhance a gripping property in wetting. Moreover, the opening edge e1 of the siping groove g1 can produce a so-called edge effect. In other words, the opening edge e1 abuts on a surface of a human hand so that a slipping difficulty can be exhibited.
The grip 8 receives a force such as a pressing force or a twisting force from a hand of a player. By the force, the fall-down of the block might be generated as described above. By the siping groove g1 bent in the depth direction, the fall-down can be suppressed. By the siping groove g1 bent in the depth direction, a force acting on the grip is effectively dispersed so that the fall-down can be suppressed. Furthermore, the opening edge e1 is bent. Therefore, the dispersion of the force is promoted still more so that the fall-down suppressing effect can further be enhanced. By the fall-down suppressing effect, an excessive deformation of the grip is suppressed so that the behavior of the club in a swing can be stabilized.
In order to enhance the gripping property in wetting and to reduce a manufacturing cost for the mold, the width Wg is preferably equal to or greater than 0.15 mm and is more preferably equal to or greater than 0.20 mm. In some cases in which the width Wg is excessively great, the opening edge e1 touches a hand to generate a rough feeling. Consequently, a grip feeling might be deteriorated. In the case in which the width Wg is excessively great, moreover, a rigidity of the grip is reduced so that the behavior of the club might be unstable in the swing or the swing might be unstable. From these viewpoints, the width Wg is preferably equal to or smaller than 1.5 mm, is more preferably equal to or smaller than 1.4 mm and is further preferably equal to or smaller than 1.3 mm.
In
In order to suppress the excessive deformation of the grip, and particularly, to enhance the gripping property in drying, the JIS-A hardness of the grip is preferably equal to or greater than 30, is more preferably equal to or greater than 35, and is particularly preferably equal to or greater than 40. In order to prevent the grip feeling from being excessively hard and to enhance the gripping property in the wetting, the JIS-A hardness of the grip is preferably equal to or smaller than 70, is more preferably equal to or smaller than 60, and is particularly preferably equal to or smaller than 50. The JIS-A hardness is measured in accordance with the JIS-K-6253 provision.
In the present invention, an installation range of the siping groove is not restricted. The siping groove may be provided over the whole surface of the grip or a part of the surface of the grip. The siping groove may be provided over a whole part in the circumferential direction of the grip or a part in the circumferential direction of the grip.
Although the advantages of the present invention will be apparent from examples, the present invention should not be construed restrictively based on description of the examples.
1.8% by weight of sulfur, 62.5% by weight of polyisoprene (an isoprene rubber), 5.5% by weight of carbon black, and 22.2% by weight of an inorganic component were blended to obtain a rubber composition. For the inorganic component, Al2O3, SiO2, CaO, Fe2O3, ZnO and BaSO4 were used. The rubber composition was subjected to press molding by using the press mold so that a grip according to an example 1 was obtained. The siping groove shown in
A grip and a golf club according to an example 2 were obtained in the same manner as in the example 1 except that a configuration of a siping groove was set to be the configuration shown in
A grip and a golf club according to a comparative example 1 were obtained in the same manner as in the example 1 except that a configuration of a siping groove was set to be the configuration shown in
A grip and a golf club according to a comparative example 2 were obtained in the same manner as in the comparative example 1 except that a depth F1 was changed to be 1.00 mm.
Specifications and evaluation results in the examples and the comparative examples are shown in the following Table 1.
The examples and the comparative examples were evaluated by the following method.
A surface of a grip was worn by means of a Gakushin type friction testing machine using No. 220 sandpaper in place of white cotton in accordance with the JIS L 0849 provision. An amount of wear was measured by 500 sliding operations of a cut grip piece and the sandpaper. An index number of the amount of wear is shown in the following Table 1. The amount of wear is expressed in an index number with an amount of wear in the example 1 set to be 100. The index number is shown in the following Table 1. A greater index number indicates a larger amount of wear.
Ten golf players evaluated a stability of a swing in five grades of one to five marks. An evaluation of the example 1 was set to be three marks, the highest mark was set to be five and the lowest mark was set to be one. An average value of the ten golf players is shown in the following Table 1. The mark was rounded below a decimal place. A smaller deformation of a grip and a higher stability of the swing were set to be higher marks. An insufficient rigidity of the grip and a lower stability of the swing were set to be lower marks. The feeling was evaluated in a state in which a surface of the grip was not wetted (a dry state).
The surface of the grip was wetted and a swing was then carried out, and a gripping property in wetting was evaluated. An evaluation in the example 1 was set to be three marks, the highest mark was set to be five, and the lowest mark was set to be one. An average value of the ten golfers is shown in the following Table 1. The mark was rounded below a decimal place. A smaller slip of the grip was set to be a higher mark. A greater slip was set to be a lower mark.
As shown in the Table 1, the evaluation of the examples is higher than the evaluation of the comparative examples. From the results of the evaluation, the advantage of the present invention is apparent.
The present invention can be applied to grips of all golf clubs. Examples of the golf club include a golf club of a wood type, a golf club of an iron type and a patter club.
The above description is only illustrative and various changes can be made without departing from the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-313418 | Dec 2007 | JP | national |
