GB2211427A

GB2211427A - Adjustment means for golf clubs and the like

Info

Publication number: GB2211427A
Application number: GB8829387A
Authority: GB
Inventors: Noriyuki Suganuma
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-12-18
Filing date: 1988-12-16
Publication date: 1989-07-05
Anticipated expiration: 2008-12-16
Also published as: GB8829387D0; GB2211427B

Abstract

In sporting equipment such as a golf club, tennis racket ski or ski-pole having an equilibrium point at a position between two ends in the longitudinal direction of the equipment, weight distribution is adjusted by means of a weight 5 the position of which can be adjusted using a lead screw 6. Other techniques include grinding and accurate moulding. A balancing apparatus for this process is also provided. <IMAGE>

Description

TITLE OF THE INVENTION: Sporting Equipment, Method of Manufacturing the Same, and Measurement Apparatus therefor BACKGROUND OF THE INVENTION: Field of the Invention The present invention relates to sporting equipment accompanying rotation, such as a baseball bat, a softball bat, a hockey stick, a golf club, a golf putter, a tennis racket, a badminton racket, a ski stick, a ski (its adjustment is performed while a binding and a boot are attached thereto), and the like, a method of manufacturing the same, and a measurement apparatus therefor.

The present invention proposes a missing link associated with rotation in the field of classical dynamics, and is a fundamental technique capable of being applied to every rotational structure as well as sporting equipment.

Prior Art In conventional sporting equipment accompanying rotation, control accuracy of equipment during use has become improved by techniques associated with an overall weight, elasticity, mechanical strength, structure, and shape including raw materials of equipment or its components, techniques of appropriately converting a feeling of use or sense of weight of equipment during use into a physical quantity such as a moment or inertial moment, and the like.

However, improvement of control accuracy of sporting equipment which exhibits movement as a complicated combination of linear and rotational movement including a transient state from a static state to a dynamic state is very important but is a subject matter difficult to achieve.

Therefore, if a player selects equipment that he believes it suits, he must be accustomed to the equipment to be skilled.

SUMMARY OF THE INVENTION: The present invention has been made to provide sporting equipment, a method of manufacturing the same, and a measurement apparatus therefor, which can partially solve the above-mentioned problems of the conventional sporting equipment accompanying rotation, can eliminate disadvantageously erroneous control during play, and is easily used.

An embodiment wherein the present invention is applied to a golf club will be described with reference to the accompanying drawings.

Fig. 3 shows a golf club according to an embodiment of the present invention In this golf club, a cylindrical wood tip 5 is fixed inside a shaft of a grip end portion A, and lead 6 for adjustment is inserted from a hole portion of a synthetic rubber grip. The golf club is attached to a measurement apparatus shown in Fig. 1, so that the central line in the longitudinal direction of the golf club is horizontal.

The golf club is manually rotated like a see-saw to have an equilibrium point in its longitudinal direction as a rotational axis, and the lead for adjustment is increased/decreased, and the equilibrium point is aligned with the rotational axis since it is moved when the lead is increased/decreased, so that the above-mentioned manual rotating operation can be most lightly performed, that is, an axial stress is substantially minimized. The abovementioned attachement on the apparatus and the manual rotating operations are repeated.

Note that the lead for adjustment can be replaced with other materials, and can be semi-fixed using a screw.

Meanwhile, equipment which can vary its longitudinal length, e.g., a tennis racket or badminton racket is manually rotated like a see-saw to have the equilibrium point in the longitudinal direction as the rotational axis.

The longitudinal length of the equipment is varied, and the equilibrium point is aligned with the rotational axis since it is moved when the length is varied, so that the above operation can be most lightly performed, that is, an axial stress can be substantially minimized. The abovementioned attachement on the apparatus and the manual rotating operations are repeated to adjust the equipment.

For skis, in order to cope with different types of bindings and ski boots, measurement must be performed in a use state wherein the bindings and ski boots are attached and'fixed to the skis. A wrist band attached to the grip end of each ski stick must also be adjusted in a state resembling a state in use.

For a baseball bat, for example, a metal bat can be adjusted by grinding. When a bat is manufactured by casting, a metal mold is precisely fabricated to achieve the object.

The measurement apparatus shown in Fig. 1 has a simple structure wherein a symmetrical rotational test bench 4 to which test sample metal attachments 2 and a rotational shaft 3 are attached to a stable base 1 through two bearings, so that rotation can be freely made within a predetermined angular range.

In place of this apparatus, a dynamic equilibrium tester for measuring an eccentricity of a rotary member is used together with an adapter for fixing a test sample, and the test sample is measured at an appropriate rotational speed, so that equipment can be adjusted with high accuracy.

From the viewpoint of dynamics, "the center of mass of an article which makes two-dimensional movement moves as if the total mass of the article is concentrated on the center and all the external forces are applied thereto".

The linear movement is caused by a primary moment, and the above statement is approved to be valid.

However, a secondary moment is a physical quantity associated with the rotation, and the centers of secondary moments at one and the other ends of all the articles cannot always-coincide with the center of the primary moment. For example, it is obvious that the centers of the primary and secondary moments of mass points of 1 g and 3 g are at different positions.

Articles in which he centers of the primary and the secondary moments coincide with each other are limited to structures having specific shape and mass distribution (e.g., a sphere or rod having a uniform density). In sporting equipment, unless the adjustment according to the technique of the present invention is made, the centers of the primary and secondary moments cannot coincide with each other even in only the longitudinal direction due to their structure or shape.

When an article in which the centers of the .primary and secondary moments coincide with each other and an article in which the centers do not coincide with each other are mounted on the rotational test bench 4, and are rotated at their two ends, the article in which the centers of the primary and secondary moments coincide with each other can be lightly and manually moved. However, the article in which the centers of the primary and secondary moments do not coincide with each other cannot be lightly rotated. As can be seen from this test, an axial stress acts on the rotational shaft 3.

It is supposed that the sporting equipment is subjected to a complicated combination of a transition from a static state to a dynamic state, a transition from linear movement to rotation, a variation in radius of rotation, a variation in movement plane, and the like, and a player is required to accurately control the equipment.

Therefore, in the sporting equipment according to the present invention, the center of mass and the centers of the secondary moments at two ends with respect to the center of mass in the rotation substantially coincide with each other, and control of the equipment can be facilitated.

Since action and reaction of the two end portions with respect to the center of mass cancel each other in correspondence with the linear movement or rotation of the sporting equipment, complicated movement during play of this equipment can be readily controlled.

BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is a front view when a measurement apparatus according to an embodiment ofthe present invention is placed along a longitudinal direction of sporting equipment; Fig. 2 is a side view of the measurement apparatus shown in Fig. 1; and Fig. 3 is a front view showing an embodiment of a golf club as sporting equipment according to the present invention when the central line in the longitudinal direction of the golf club coincides with the horizontal axis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT: When the present invention was applied to a golf club (driver) having a length of 43" and a weight of 365 g, a l.5-g counterweight was placed in a portion near a grip end, so that a weight distribution could be appropriately adjusted. It can be considered that adjustment can be made using a counterweight having a weight less than 1/100 that of sporting equipment.

Ten or more players including amateurs and professionals were made to try to hit a ball using the golf club which was optimally adjusted according to the present invention. All the players stated their impressions that erroneous hitting was reduced and the golf club adjusted by the present invention could easily hit a ball as compared to a golf club which was not optimally adjusted. For a baseball bat, many players approved that the bat adjusted according to the present invention could easily hit a ball.

The effect of the present invention can be easily demonstrated as follows. For example, commercially available 5-g lead for adjusting a weight is adhered to a grip end of a tennis racket, and carefully and repetitively hits a ball while cutting off the lead by about 0.2 g each time.

The present invention can be applied to a structure accompanying rotation such as a hammer, axe, and the like as well as various other kinds of sporting equipment.

Claims

WHAT IS CLAIMED IS:

1. Sporting equipment having an equilibrium point at a position between two ends in the longitudinal direction of said equipment, wherein a weight distribution is adjusted so that an axial stress due to rotation is minimized when the two ends of said equipment are rotated to have the equilibrium point or a center of gravity as a rotational axis.

2. Sporting equipment according to claim 1, wherein said sporting equipment comprises one or a plurality of fixed or semi-fixed members or devices capable of adjusting a weight distribution, or has a ball hitting portion at one end portion and a grip portion gripped by a player at the other end portion, so that a longitudinal length can be varied.

3. A method of manufacturing sporting equipment which comprises one or a plurality of fixed or semi-fixed members or devices capable of adjusting a weight distribution, or has a ball hitting portion at one end portion and a grip portion gripped by a player at the other end portion so that a longitudinal length can be varied, and which-has an equilibrium point at a position between two ends in the longitudinal direction of said equipment, including the step of adjusting a weight distribution, so that an axial stress due to rotation is minimized when two ends of said equipment are rotated to have the equilibrium point or a center of gravity as a rotational axis.

4. A measurement apparatus wherein a symmetrical rotational test bench (4) having test sample attaching devices (2) is mounted on a stable base (1) to be rotatable about a rotational shaft (3) within a predetermined angular range.