Golf Club Heads Research Articles

Fabricating sports equipment components via powder metallurgy

Powder metallurgy (P/M) offers a viable, cost-effective approach to fabricating sports and leisure equipment components. Both complex, monolithic parts and parts produced from materials of quite different densities can be manufactured by this technique. In the latter category, lightweight titanium and heavyweight tungsten can be used in combination to optimally distribute mass, such as in golf club heads. Examples of P/M components used in golfing, skating, baseball, and even darts are presented.

アモルファス・ナノ結晶制御と高機能材料 金属ガラス粉末の固化成形および鍛造成形と工業化

Recently, a number of amorphous alloys having a temperature range of supercooled liquid above 50K before crystallization and high glass-forming ability have been discovered. The new amorphous alloys are called metallic glasses. Such metallic glasses can be fabricated from the melt in a bulk form with a thickness of-10mm at slow cooling rates of the order of 1-100 K/s. The metallic glasses, moreover, exhibit useful properties such as high strength and high stiffness at ambient temperature. We have found that the metallic glasses exhibited high-strain-rate superplasticity at temperatures above the glass transition temperature. The superplasticity inherent in the supercooled liquid seems to give a unique approach for the synthesis of bulk metallic glasses by powder metallurgy processing. We, therefore, tried to consolidate the metallic glass powders using the superplasticity. We consequently succeeded in synthesis of bulk metallic glasses with the same tensile strength as the cast bulk glassy alloy and melt-spun metallic glass ribbon. Recently, the bulk metallic glasses produced by extrusion of gas-atomized glass powders have been commercially used as a face material of newly designed iron-type and patter-type golf club heads.

Application of Zr-Based Bulk Glassy Alloys to Golf Clubs

Bulk glassy alloys have high tensile strength, while the Young's modulus is lower by 20 to 40% than those for the corresponding crystalline alloys. These unique mechanical properties are effective to increase the coefficient of restitution at the impact between a golf club and a golf ball. Bulk glassy alloys have in general been produced by the copper mold casting and die casting methods. We have developed a new manufacturing process for Zr-based bulk glassy alloys. By the use of the new process, we have succeeded in producing a glassy Zr-Al-Ni-Cu alloy in a shell shape with a dimension of about 90 x 40 mm and a thickness of 3 mm for glassy driver golf clubs. It exhibits excellent mechanical properties such as tensile strength of 1700MPa, Young's modulus of 81 GPa, and impact fracture toughness of 130 kJ/m 2 . These properties are suitable for the material for driver golf club heads. The glassy driver golf club with the shell shape in the impact region was confirmed to have a high coefficient of restitution.

CONDENSE: A concurrent design evaluation system for product design

In dealing with the issue of integrating design and manufacturing, concurrent design evaluation plays an important role. This paper presents a concurrent design evaluation system (CONDENSE) developed to help product designers in evaluating possible design solutions and design alternatives during the early stage of design. It consists of two important functions: a qualitative aspect evaluation applied during the stage of searching for combinations of solution principles to help determine the design specifications, and a quantitative aspect evaluation applied to provide information on performance, assemblability, manufacturability and costs to facilitate design selection. The framework of CONDENSE is based on a blackboard architecture that requires the classification of knowledge into appropriate knowledge sources. As design data are interrelated and may have uncertainty, a graph decomposition algorithm is used in constructing the knowledge sources, and a linguistic evaluation module is integrated with the qualitative aspect evaluation subsystem to deal with data uncertainty. The proposed system has been validated with respect to the design of golf club heads. The results, which have been validated by experienced designers, are promising and can contribute to the speed-up of design and development, improvement of design quality and facilitation of design selection.

24S ゴルフ・ボールの斜め衝突のシミュレーションと粘弾性の影響(スポーツ工学シンポジウム2001)

It is a common knowledge that golf club heads of thin-walled structure provide higher coefficients of restitution than those of solid. However the mechanism of producing higher restitution characteristics has not been clearly explained by means of computer simulation or experiment. This paper describes how the impedance of impact face, that is, the wall-thickness affects the rebound conditions of a ball after collision, that is, velocity, angle and spin rate by conducting computer simulations based on Finite Element Method. The material properties of balls were determined as a three-element visco-elastic model by conducting experiments to let golf balls collide with a rigid target and to obtain load and deformation relationship during collision. The coefficient of friction was also determined by comparing with the experiments to let balls collide with circular plates. By using the above conditions the oblique impact of balls with circular plates of various thickness could be simulated under various impact conditions and the comparison with experimental results could be made. The results show that the coefficients of restitution maximize approximately at 3mm for plate thickness.

34S ゴルフボールのコンプレッションナンバーと反発係数の関係

A relation between the compression number and the coefficient of restitution of golf balls is examined. The compression number for golf balls of three specific construction types (wound, two-piece and three-piece balls) is measured from compression tests using an Instron testing machine at a constant crosshead speed. The coefficient of restitution is determined by means of a new golf ball launching device. Long elastic bars made of three different materials used for golf clubheads are employed to measure contact force histories. It is shown that the compression number remains constant less than a displacement rate of 10 mm/min, and the coefficient of restitution is independent of the compression number value, depending on the incoming velocity (20-50m/s) as well as on clubhead materials.

Hollow golf club head modal characteristics: Determination and impact applications

The design of modern hollow golf club heads is a labor-intensive process involving extensive performance festing both by robotic and real golfers. This paper describes how, by correlating club head mechanical behavior with functional performance, it will become possible to use validated computational models to predict this performance as well as related contributions to the ill-defined concept of “feel”. Successful use of experimental modal analysis to validate a hollow golf club head finite element model is reported. Modal tests employing noncontacting, laser-based transducers facilitated identification of the natural frequencies and corresponding modeshapes for the three main surfaces of the club head. The experimental data suggest predominantly different modal characteristics for each surface, and this compares favorably with equivalent data obtained from the finite element model. The modal data are also used to identify surfaces responsible for particular frequency components present in the club head impact sound spectrum. The potential for detailed impact performance prediction using the finite element model is further demonstrated by comparison of computed and experimental club head acceleration measurements recorded during simulated and actual club-ball impacts.

Metallic Glasses Bulk Up

Vitreloy, a metallic–glass alloy of zirconium and beryllium from Amorphous Technologies International (ATI) in Laguna Niquel, CA, is extensively being used in golf clubs. Liquidmetal golf-club heads are fabricated from an amorphous metal alloy that has excellent rebound and vibration-absorbing properties. Research indicates that the prized physical properties of metallic glasses arise in large part from their lack of grain boundaries, which can serve as points of weakness. Liquidmetal putters have a ‘soft’ feel when striking the ball, which the makers claim provides players with improved touch on putting greens. The elevated strength-to-weight ratios exhibited by Liquidmetal alloys make the metallic glasses promising for a range of high-performance applications. Sports enthusiasts may also soon find bulk metallic glasses like Vitreloy in other high-end sporting goods such as tennis rackets, baseball bats, bicycle frames, hunting bows, and even edged tools such as axes. ATl management stated that high-performance sporting goods are only a first step in the market; the new family of materials could also be promising for other, more serious applications.

A Discussion of Iron Golf Club Head Inertia Tensors and Their Effects on the Golfer

This paper discusses the inertia tensors of iron golf club heads and their influence on the swing of a golfer and the behavior of the golf club. Inertia tensors of various five-iron club head configurations were determined using solid modeling and were compared with equivalent solid ellipsoids. A golf swing and club behavior analysis was performed using a computer model comprised of a 3D parametric flexible model of a golf club driven with data from a recorded golf swing, and an impact function. The impact results were verified experimentally. The analysis without impact determined that altering club head inertia had a minor effect on the torque required to swing the club and the deflections of the club head at the time of impact. The analysis with an eccentric impact found that altering club head inertia had a major effect on transmitted forces and torques and a moderate effect on deflection of the club head.

Analytical design of iron golf club heads.

This paper describes an analytical method for the design of iron golf club heads. The method divides the club head into the basic shape and the back-weighting. The basic shape, which consists of the club face profile, hosel and club face-hosel blend section, is configured directly from geometric specifications. An adaptive random search optimization algorithm is employed to design the back-weighting to obtain desired mass properties for the club head. The designer has control of the general configuration of the back-weighting through the method of geometric influencing. Several dynamically equivalent iron club heads are presented that were designed using this method.

Analytical design of iron golf club heads

Analytical design of iron golf club heads

温度制御による木材のマイクロ波加熱減圧乾燥

The objective of this study is to clarify the practical features of the new wood drying method, which combines microwave heating and vaccum, by determining the drying time and the quality of dried wood. To measure the temperature of drying wood in a microwave electric field, a thermal sensor was developed and incorporated into the microwave heating-vaccum dryer. The woods were dried by controlling the wood temperature. Beech (Fagus crenata), spruce (Picea spp.) lumbers, and persimon (Diospyros Kaki) blocks curved roughly for golf club heads were dried by the proposed new method. The results obtained are summarized as follows;(1) The thermal sensor with the function of reflecting microwaves was improved so as to provide accurate measurements of wood temperature during heating in the microwave field.(2) By controlling the wood temperature in the new drying method, none of such defects as surface checking and honeycomb appeared in dried lumbers, and the drying time was remarkably shortened compared with the conventional kiln-drying.(3) The present microwave heating-vaccum drying method is suitable for variously shaped wood pieces besides lumbers with flat surfaces.(4) The relation expressed by V=exp(a+bT) existed between the drying rate V and the wood temperature T irrespective of wood species. The drying rate V was highest for sapwood of beech, intermediate for spruce and persimon, and lowest for the heartwood of beech. The value of b was highest for the sapwood of beech, intermediate for the heartwood of beech and persimon, and lowest for spruce.(5) The drying operation based on the wood temperature was effective to shorten the drying time and to prevent drying defects.

Some mid 17th-century golfclub heads found during underwater excavations and their significance for the study of the early history of the game of golf

Some mid 17th-century golfclub heads found during underwater excavations and their significance for the study of the early history of the game of golf