GB2370513A

GB2370513A - A golf club face having a thick walled area

Info

Publication number: GB2370513A
Application number: GB0128914A
Authority: GB
Inventors: Minoru Yoneyama
Original assignee: Yonex KK
Current assignee: Yonex KK
Priority date: 2000-12-04
Filing date: 2001-12-03
Publication date: 2002-07-03
Also published as: GB0128914D0; JP2002165904A; US20020068646A1

Abstract

The present invention relates to a face structure of a hollow-body, metal golf club head, comprising a face of laterally elongated shape, a crown and a sole plate fixed thereto, and particularly to a face structure having thin-walled areas for extended, stable carry and horizontally stabled trajectory. The face 11 has a thick-walled area 15a of uniform thickness formed at the backside thereof, which extends horizontally from the heel side to the toe side thereof over the hitting area 16a, and with thin-walled areas 15b, 15c of uniform thickness formed above and below the thick-walled area 15a. An elongated portion 17 for fixing the crown and the sole plate is formed projecting backward on the backside periphery of the face 15.

Description

23705 1 3

FACE STRUCTURE OF HoLLow-Borly METAL GOLF CLUB HEAD Background of the Invention

Field of the Invention

5 The present invention relates to a face structure of a hollow-body, metal golf club head having a face of a laterally elongated shape with a crown and a sole plate fixed thereto.

Description of the Related Art

Traditionally, wood clubs used to traverse great 10 distances have employed a hollow-body, metal club head comprised of a face with a crown and a sole plate welded to its backside. The face has been variously improved to have higher resilience so as to carry a ball much farther.

For example, a high resilience was realized by means 15 of titanium alloy used as a head material, which has sufficient strength in order for the face to be thin-walled.

This is because the thinner-walled face makes the backward elastic deflection of the face at impact larger, as shown in FIGS. 2B, 2C with solid line, and therefore it makes the 20 elastic elongation A (indicated as An, Ah in FIG. 2) of the face, especially near the back surface, larger as a whole, resulting in larger total elastic energy Et (as defined in formula(1) below) accumulated in the face.

Et=ax(kx\2)/2+p...(1) 25 Here, k is an elastic constant of the face in the direction of the elastic elongation X, a is a coefficient varying related to the elastic elongation distribution in the

thickness direction., and IS s an elastic energy due o he othe- _ac,ors.

On the other hand, in Japanese Patent La c-oper Pub' cation No. rFei '3it322,3, as shown in FIG. 3, a face S structure improvemen_ Bleat zing 'I gher residence ob_a_ne:.

by deceasing a th caress o' a- area around a ' ' t'.15 area 23 is proposed. A -h n-wa''ed area 25 Provided around he hitting area 23: a.<es no. only he hi, no area 23 co be o-

higher strenqih bus also fine eras in backward e'orga= on a-' l0 _he face 21 so be 'anger i-. al' d -ec ons.

However, s -.ce fine ace has qer.eratlv 'or.qe dimension in a horlzon a2 d ect_or than n a vertical d Arc- on as shown in FIG. 2, even when has _'. e.h n-wa22ed area 25, the elastic elor.qa- on a-.re ace, espec ally Pea= -he -'ace's L5 back surface, -.s larger vet ica2 ' y than horizontally Al impact. Thus, the elastic energy Ev due to the ver-ica2 elastic elongation TV is large, and the energy Eh due to -he horizontal elongaiior. h is relatively small. In other words, the total elastic energy Et accumulated in the.'ace 2l a 20 impact is not disco bused equally to fine ve< _ical e_as_ic energy Ev and the hoc- zontal energy Ah.

Therefore, _he carry varies owing,o one variation o the total e'ast c energy Et resulted -tom the horizontally or vertically deviated hits from hi tinq area 23, namely, the 25 sweet spot. In other -fiords, the carry of an off-center hit depends not only on the amount of deviation but on the direction of the deviation. Thus, the face structure of

laterally elongated shape has tendency of ill stability in a ball carry.

Furthermore, the ball struck by an off-center hit generally has spin owin; to so-called a gear effect. As shown 5 in FIG. 2, the ball impact too close to the heel 23a of the face 21 results in slicing trajectory, and the ball impact too close to the toe 23b results in hooking. This gear effect works less when the thickness of the face 21 is smaller. Then the ball trajectory will be stably straight.

10 However the face structure 23 having a thin-walled area 25 around the hitting area 23 as shown in FIG. 3 has undesirable characteristics in ball trajectory stability especially because it has thin-walled areas 25a, 25b on both lateral sides of the hitting area 23. The contact too close 15 to the heel25a increases a slicing spin, and the contact close to the toe 25b increases a hooking spin, due to the gear effect Accordingly, this type of face structure is less stable in the ball trajectory of horizontally off-center contact.

Summery of the Invention 20 In view of the above problems, it is an object of the present invention to provide a golf club head having a face structure of laterally elongated shape with thin-walled areas therein, which realizes good stability of the trajectory both in distance and in horizontal direction, as well as sufficient 25 carry.

In order to accomplish the above and other objects, a face structure of a hollow-body, metal golf club head

according to one aspen of the preset- Denver. on comprises a face of lateral' y Gil orated shape, a crown and a sole p2a e fixed to the ace. The ace has a th c<-wa' leaf area o uniform hlckness formed a.e backside.. hereo, i C'L ex er.ds From 5 the heel side Lo _'r'e roe side r.e eof over the hi-, ng area, and with thin-wa22ec areas o'- ur.i orm thickness orbed above and below -he. L c,k-wa_led area.

The area o the th c<-wal'ec area may be Loom 30 co '02, of the total area o the face's backside.

10 The vent ca width o the 4_L'2 ck-wa'lec area...ay be Sf: = from l5mm to 20 m An elongated pot ion o'- f x n5 the crown and - e sol;_ plate may be for.ned project ins backward on the backs de periphery of the -ace.

15 The elongated port on may have the depth o - 15 m -o 25mm. The angle between the Facets backside and the eLor.gai:ed portion may be se from over 90 to 100 .

Brief Description of the Drawings

20 FIG. 1A is an elevation of a Lace structure of a golf club head according to one embodiment of the preset 1nver.t or and FIG. 1B is a sectional view taken on the line B-B in the arrows direction of FIG. FIGS. 2A-2C are the views s:rLowing the backward elastic 25 deflection produced at impact n a conventional face of laterally elongated shape, the elastic elongation v, Ah of the face, especially of the face's backside FIG. 2A Is an

s elevational view in section, FIG. 2B andFIG.2C are sectional views taken on B-B and C-C lines respectively in the arrows direction of FIG. 2A; and FIG. 3A is a side sectional view of a conventional 5 hollow-body, metal golf club head comprising a face which is shaped laterally elongated provided with a thin-walled area, and FIG. 3B is a sectional view taken on B-B in the arrows direction of FIG. 3A.

Detailed Description of the Preferred Embodiments

10 The preferred embodiments of this invention will be described in detail with reference to the accompanying drawings. The basic Japanese Patent Application No. 2000-368466 filed on December 4, 2000, the contents of which is incorporated herein by reference. FIG. 1 shows a face 15 structure of one embodiment of the present invention. FIG. 1A is an elevational view thereof and FIG. 1B is a sectional view taken on the line B-B in the arrows direction of FIG. 1A. As shown in the drawings, a club face 11 in this 20 embodiment comprises a neck 13 connected to a shaft, a face 15, and a backward elongated portion 17 projecting from the entire periphery of the face's backside. These are forged integrally from titanium alloy. Then a crown and a sole plate (not shown) are welded to the elongated portion 17 so as to 25 form a hollow-body structured golf club head.

The face 15 is shaped laterally elongated, namely, has longer width horizontally than vertically. A thick-walled

area 15a o_ U?., t orm ve' 2 cal w d h is prov ded grojec ng rom the backs de of he race, wh ch _s ex end ns r' -om the: ee_ tO the toe s de over a. nc, a ea loa at the cente o'' _re ace. The areas above and be2ow _re h c. -walled area l a 5 are th n-walLed areas 15O, 15c, as showc. n he d aw.ngs.

These two thm areas '5, lSc < -e c._he same th c'\ esa a. d are of subs an' al'v he same area.

The th:2ckness o tne h ck-wa22ed area 15a s se a the appropri te val e w h'n 2 3-2.,mm, and -he ve--_2 -a 10 width thereo2 s se ap? o?-- a.e'y w- h L:--_Onm. hus, he area ofthe it. ck--wa2le a ea '5a _s wNi.. n 30 403 0; :he oca2 Cace backside area. On the other ha d, he h ckness o: -he thinwalled areas 150, 15c s se. a- he approp- a.,e wa e with n L 8-2.2r n. These va'ues, name2y, the a ea anc 1S thickness o hose areas are determined n orde ror ne elastic ene gy Ev of the ver, cal elastic elonga _or -v o the face 15 and the elas-ic energy Eh o he horizon a2 elongation h 'o be sufficien-.ly equal when an expec--ed 'oad of hittins s imocsed at he h -'. c area 16a, -e a',ue o 20 he expected load of hit i?.g s selec ed accorcing o _ne arset user of tne club. In o her words, for a genera' c'ub the average value of some ama eu gol ers may be used, and for a made-to-order club or particular professional sol player, his own average value should be used.

25 The face 15 of such appropr' ate values will accumulate substantial' y the same amount of elastic energy at horizontally devia ed impact, as the elastic energy at

vertically deviated impact. Thus the variation of carries will be reduced, which was caused by the directional variation - of the deviation of hits.

The reason that the face structure 15 of this embodiment 5 is able to sufficiently equalize the elastic energies Eh and Ev, due to the horizontal and vertical elongations Ah, v respectively, is as follows.

Since the face 15 has the thick-walled area extending from the heel to the toe and the thin-walled areas above and 10 below the thick-walled area, the horizontal elastic constant kh of the face 15 is larger than the vertical elastic constant kv. This difference between kh and kv compensates the difference between the elastic energies Ev and Eh, namely, (Ev-Eh) due to the difference between the elastic elongations 15 TV and Ah. Thus, the total elastic energy Et accumulated at the hitting is distributed equally to the energy Eh of horizontal elongation kh and to the energy Ev of vertical elongation v.

Since the thick-walled area 15a is of sufficient, 20 horizontally uniform thickness, even a contact at areas 16b, 16c, deviated horizontally from the sweet spot, will not tend to lead to the gear effect with any spin of the ball. Thus, the trajectory will stably go straight without increasing slicing or hooking. In other words, the variation of 25 trajectory direction will be well reduced.

The elongated portion 17 is formed projecting backward from the entire periphery of face backside, and has generally

a cvlindrica2 a??earar.ce w h the ?-ojec.,on p ojec ng 20 m deep. The angle D1 w'n.:2cn he u??e<-r.'os por or o' c..e elongated po-r or. 17 oms w,.. '.e ace backs ce s lOOi' The an le ? ogress vely decreases dow.. ward and s.m n m eG at he lowest po =ion w _.n he ang e D2 o - 91.

The c-own,and he so' e ?la.e a e welded -o -:-e edges 17a, 17b o the p o, ec-2nq e2onga_ed go ior. 1 S 2 ce he weld zone s loca ecd a?a -rom -he. ace 1: by _he ae?;h o' - e projec or and de ects n we'd n5 and/or a heara -ec=ed lO one by we'd n5 a e ? ever. ed, -he race 15 wi22 be -ee om eg adat or. 2n s_-erqt'h ard ouqnness the e.?..

Moreover/ since -he anq2e D which he backs_de o the ace lS forms r ri.h he elonqaced po = on 17 s sec -o be obtuse under 100'', he s?an betwee. 'ne h -,in: area loa and.'ne edge 1S 17a, 17b or the tace por ion 11 wil2 be relat velylarge rakinq the dimens on o.ne.ace l:,?. Q consideration. Thus, _as e swinq speed o che head and h qher esilience or the.'ace are accomplished cy means of li le aerodynamic draq agains the ace lS and 2arge bend2ng momen by,ne h tt2ng or -he ace 20 l5, espec ive y Th s esul s in -u ther mprovemen n a ball ca ry.

The eason why he smallest angle, 91 , s sma''1 as compared to he uppermos anqle o- 100 is tha the aerodynamic drag at the [owes' portion, wr.ich has maximum 25 swing speed, should be as small as possible to etard he deceleration o: the head.

Though this embodlmen-ts face 15, whose thickness is

2.3-2.7mm even at the thick-walled area, is significantly thinner than the usual casting titanium alloy face, whose thickness is 2.8-3.0mm, it has still sufficient Strength.

This is because the embodiments forged face portion 11 is 5 improved in strength than a conventional cast face by approximately 20%, and because the face 15 has relatively high strength and toughness since the crown and the sole plate are welded to the elongated portion projecting therefrom. Such thin-walled face structure of this invention has realized 10 improved resilience and extended carry.

According to one aspect of the invention, since thin-walled areas are provided above and below the thick-walled area in the face, the vertical elastic constant kv of the face is smaller than the horizontal elastic constant 15 kh. Therefore, as can be understood with the above-mentioned formula (1), the elastic energy Ev will become smaller, which results in substantially equal distribution of the total energy Et into the vertical energy Ev and the horizontal energy Eh.

20 Thus, the variation of the ball distance due to the variation of direction of deviation from the face center will be reduced since the face's total elastic energy of horizontally off-center impact and vertically off-center impact are substantially the same.

25 Moreover, since the thick-walled area, extending from the heel to the toe, has uniform and sufficient thickness, the gear effect, due to the horizontally off-center contact,

wLil be reduced. Thus, the oa'l- 21 scarcely have s?ir., ard the e ore the - ajec ory v; 1 oe s,ably s-.a' ght -4i n 2. e slic' q or.-ook2 r5 Acco7din: o ano.her as?ec o he inve.7_ or., decrease 5 in durabil y of he ace due -o nsu_r-ic er_ n c.k-wa22ec area s moc f ed s nce he i7 ckwa'led area has o:/e-- 3(' 4 o-

-he o,ai area, and on he o.her- hand, decrease n ne -es22ience due _o the ns, -ic en th n-wal2ed area s a_so od fied since he th_ck-wa2led a ea has less _ha.n '0; o. -he 3 o al a-ea.

Acccrd_ng o ye another s spect o t ie nve on, - ce the ve-tica2 wid h o t. e th ck-wa''ed a ea s ove 1S=m/ 'ne ace nas sreater cu-abi2i_y due o rhe suf_'lc en idth oeir: resls ant to s ron5 mpac, and acdi.ionally, w cer area -ee 1S rom gear ef ec rea''zes more s able and straignt rajec or-y On,he othe' hanc/ s nce he same width 1s u? o Ornm, sood esillence is real zed by mod fyinq he decrease o_ resilience due to _nsufficien a ea of the thin--walled area Acco d_rls -o fu'-.le'-ascec of he r.ven on, since -ne c own and he so' e p'a e are fixed to the elonsa ed por- o, -he fi.<lng port or.: B apar rom r.e face. Thus, -he defec s or weakening o r xi:1C, or example poor weldlnc or tcherma2 deqradat on caused oy welding, are prevented 'om oe n5 occurred in t'ne face, result 2nq in prevention of decrease in DS strength and toughness of the face, which requires sufficient impact resistance.

Furthermore, as the strength and toughness are improved,

the thickness of the face is able to be smaller so as to realize better resilience.

According to another aspect of the invention, since the elongated portion has the depth of over 15mm, the fixing zone 5 is located sufficiently apart from the face. Thus the face will have sufficient strength and toughness even with poor welding or thermal degradation in the fixing zone.

Additionally, since the elongated portion has the depth of under 2Smm, this portion is able to be deep drawn, by presswork 10 or the like, integrally with the face so as to reduce the manufacturing cost significantly.

According to further aspect of the invention, since the angle which the face's backside forms with the elongated portion is set at obtuse angle under 100 , the span between IS the hitting area and the edge of the face is large considering the dimension of the face. Thus, faster swing speed of the head and higher resilience of the face are accomplished by means of little air resistance against the face and large bending moment of the face caused by load of hitting, 20 respectively.

Having described a specific embodiment of the invention, the invention should not be taken limitative by any of the details of the description and various changes and

modifications may be made without departing from the spirit 25 and scope of the invention.

For example, the upper and lower thin-walled areas may be of different thickness, though they were equal in the above

embod1 meet, as ions as the Blast c ene-gv is aqua _y dis.riouted in horn zon-al and ver.'ca1 pi ec ons. When The lower thln-wa: lent area s tricker, -o= exams e, he cen.=er of gravity will cescen c, rest A no, n the advantage rho_ -he 5 bat will be brought higher eas By.

Claims

What is claimed is:

1. A face structure of a hollow-body, metal golf club head comprising: a face of laterally elongated shape; 5 a crown and a sole plate fixed to said face; said face having a thick-walled area of uniform thickness formed at the backside thereof and thin-walled areas of uniform thickness formed above and below said thick-walled area, the thick-walled area extending from the 10 heel side to the toe side of said face over the hitting area.

2. A face structure of a hollow-body, metal golf club head as claimed in claim 1, wherein the area of said thick-walled area is from 30 to 40% of the total area of said face's backside.

15

3. A face structure of a hollow-body, metal golf club head as claimed in claim 1, wherein a vertical width of said thick-walled area is set from 15mm to 20mm.

4. A face structure of a hollow-body, metal golf club head as claimed in claim 1 or 2, wherein an elongated portion 20 for fixing said crown and said sole plate is formed projecting backward on the backside periphery of said face.

5. A face structure of a hollow-body, metal golf club head as claimed in claim 3, wherein an elongated portion for fixing said crown and said sole plate is formed projecting 25 backward on the backside periphery of said face.

6. A face structure of a hollow-body, metal golf club head as claimed in claim 4, wherein said elongated portion

has depth of 15mm JO 25..

7. Afacesi uc._u eoh o7'ow body,.e a' gol-c2-, head as c'a:.med in chasm 5, wr.e-e r said elongated ? - on has depth of L5mm.ro 25mm" 5

8.. aces uc u-eo. a oLiow-body, mere go_ c need as claimed Or any one o- c us J to, ; wne-e. B^n am e between said Ace's acts de sac said e or.:a-ea ? : 1- is set Prom over 90 JO 100 .