Golf club head equipped with face insert

The present invention relates to a golf club head. In particular, the present invention relates to a golf club head having a body member and a face insert made of different materials. More specifically, the present invention relates to golf club heads that can be customized and have suitable face wear resistance.

Golf clubs are usually manufactured with standard values for lie angle, loft angle, face offset, etc. However, individual golfers typically want clubs with dimensions that differ from standard values. To custom order these clubs, the hosel portion, which is the socket in the club head into which the shaft is inserted, is usually bent to change the standard dimensions of the club head. The requirement to refurbish the club in this way requires the club head to be made of a relatively soft and malleable material.

A groove is usually formed on the face of the club head that the golf ball hits during use. These grooves grab the golf ball and spin it. This spin action enhances the aerodynamic effect of the dimples of the golf ball, allowing a skilled golfer to control the trajectory of the ball in flight and the rolling of the ball after landing. Normally, with normal use, the face of a golf club with grooves wears considerably. This wear or erosion of the club face is increased and facilitated by the soft material required for customizing the club head, resulting in a reduced volume of the groove and a rounded edge of the groove. The design of the groove is important for proper spin on the golf ball, so changes in the geometry of the groove will result in poor performance.

Conventional attempts to increase spin on the ball or improve face wear include coating the club face. These coatings protect against surface roughness as they prevent wear. However, such coatings do not reduce material wear from the surface of the face. In some cases, normal use tends to wear relatively quickly, exposing the material of the club head. Once exposed, the club face material wears and performance deteriorates. Other attempts to reduce wear include forming the entire club head with a wear resistant material such as chrome plating. While these clubs are good in terms of wear resistance of the face, the wear resistant material has very low ductility and malleability, which has the undesired effect of practically hindering custom ordering of the club.

<p> Therefore, there is a need for an improved golf club head that is customizable and has adequate wear resistance for the face.</p><p> The golf club head of the present invention has a main body made of a first material and an insert made of a second material. The first material is softer than the second material. The golf club head has a sole. The material of the sole is harder than the material of the body, and the material of the sole is preferably the same as the material of the insert. The golf club head is preferably an iron type golf club.</p><p> The second material preferably has a wear resistance of approximately 40 to 0. More preferably, the second material has a wear resistance of approximately 35 to 0. The first material preferably has an elongation of approximately 13% or more and an extreme elongation of approximately 15% to approximately 21%.</p><p> The insert preferably comprises a striking face with a groove. These grooves have a certain width. This width varies by almost 40% or less in the blast test. More preferably, this width varies by about 30% or less in the blast test, and even more preferably by about 25% or less in the blast test.</p><p> The first and preferably have a Rockwell C hardness of at most approximately 30. The second material preferably has a Rockwell C hardness of approximately 50 to approximately 55.</p><p> The first and second materials can be steel. The second material preferably contains approximately 1.40% to approximately 1.75% carbon and approximately 10% to approximately 18.0% 0 chromium. More preferably, the second material contains approximately 1.50% to approximately 1.65% carbon and approximately 15.5% to approximately 16.5% chromium. Instead, the second material preferably has a chromium to carbon ratio of approximately 10: 1 to approximately 11: 1.</p>

The present invention will be described with reference to the accompanying drawings in which the same reference numerals represent similar elements.

FIG. 1 shows a golf club head 1 according to the present invention. The club head 1 is preferably an iron-type club head and has a body 10, which body 10 includes a heel 11, a toe 12, a crown 13 and a sole 14. A hosel 15 is provided on the heel 11. A shaft (not shown) is coupled to the club head 1 within the hosel 15. The club head 1 also has a striking face 20. The angle formed by the ground and the striking face 20 when the club head 1 is placed on the ground is the loft angle. The vertical height of a golf shot is mainly determined by the loft angle. The angle formed by the axis of the hosel 15 and the longitudinal axis of the sole 14 is the lie angle. The vertical distance between the axis of hosel 15 and the central axis of club head 1 is the club offset, if any.

Golf club heads are typically manufactured with loft angle, lie angle, offset and other dimensions as standard values, but individual golfers often require changes to the club head to suit their swing. For example, one golfer's swing requires the lie angle of his club to be 2 ° larger than the standard value. To obtain the club dimensions required by individual golfers, the club head 1 is custom made by varying the standard values. This usually requires fixing the club head with a screw or similar device or bending the hosel 15 in order to set the loft angle, lie angle, offset, etc. to desired values. To facilitate this task, the club head 1 is formed of a first relatively soft malleable material.

The striking face 20 is used to come into contact with the golf ball during normal use. The striking face 20 includes a groove 22. Groove 22 grabs the golf ball and spins it. This spin action enhances the aerodynamic effect of the dimples of the golf ball, allowing a skilled golfer to control the trajectory of the ball in flight and the rolling of the ball after landing. The striking face 20 and the groove 22 are worn by repeated contact with the striking face 20 through daily use. The striking face 20 is formed of a wear-resistant second material in order to delay the wear of the striking face 20 and to keep the geometric structure of the groove 22 unchanged. When a material is wear resistant, it tends to be less ductile. Since ductility is desirable for the material forming the body 10, the striking face 20 is preferably an insert that is coupled to the body 10. Any binding means can be used, but adhesion and brazing are preferred.

The first material is a relatively soft ductile material and can be the material normally used to form golf clubs. Iron-type golf clubs are usually made of carbon steel or relatively soft stainless steel. Preferred carbon steels include 1025, 8620 and S20C carbon, and preferred stainless steels include 431, 303 and 329. Forming the body 10 with one of these materials allows the club head 1 to be custom made to obtain dimensions that suit the individual swing of the user. Elongation of these materials is typically in the range of approximately 13% or higher, preferably approximately 15% to 21% in conventional standard-based tests.

The second material is an abrasion resistant material. A convenient way to classify and classify the wear resistance of a material is by ASTM G65, which is called the "standard test method for measuring wear using a dry sand / rubber wheel device". Procedure A, which is a relatively rigorous test on metallic materials, is the preferred procedure. This test characterizes the material with respect to weight loss (weight loss) under controlled set laboratory conditions. A sample of material is held against the rubber wheel under a specific force. While pressing the sample against the wheel, the wheel group is rotated at a specific rotational speed, and the aggregate material is introduced into the contact area between the wheel and the sample at a specific flow rate. After a certain period of time, the sample is removed and volume reduction is measured. Test results are reported as volume reduction in cubic millimeters. Relatively high wear, or wear-resistant material volume loss, is relatively low. Therefore, a relatively low wear resistance number represents good wear resistance. Typical golf club materials include cast stainless steel with a wear resistance of about 200 and carbon steel with a wear resistance of about 80. The second material in the present invention preferably has a wear resistance of 40 or less, and more preferably 35 or less.

During the development of the present invention, blast tests were performed in a number of clubs. Figure 2 shows the form of the blast test. The club head 100 was positioned and held with its face 102 approximately perpendicular, i.e., approximately perpendicular to the horizontal axis AH. The aggregate material was made to collide with the face 102 along the flow path FP forming an angle α with respect to the horizontal axis AH. A Zero model Pulsar III blast cabinet from Clemco Industries (Washington Missouri) was used for testing. The machine was operated with a 1/4 inch nozzle at 3.12 cubic feet of laminated wood feed per hour according to standard operating procedures. Quartz glass beads were used as the laminated wood, and the blast pressure was 60 psi. The blast angle α was set to 20 °, and the impact angle with respect to the face 102 was set to 70 °. The duration of the blast test was 40 minutes. Groove widths before and after the blasting operation were measured.

The first club tested was a rough-finished Vokey wedge. Vokey wedges are made of 8620 carbon steel without a protective chrome finish. The drawings showing the contours of the pre-blast and post-blast grooves for the Vokey wedge are for illustration purposes only. FIG. 3 shows a side view of the groove 50 of the Vokey wedge before the blast test. The image is 80x. The groove 50 has uniform dimensions and is almost U-shaped. The line F corresponding to the plane of the club face is shown for illustrative purposes. The width of the groove 50 is 0.045 inches. FIG. 4 shows a side view of the groove 50 of the Vokey wedge after the blast test. The groove 50 is considerably enlarged at the boundary between the groove and the face, which is a portion of the groove that is gripped by contacting the golf ball during use. The width of the groove 50 after blasting is 0.082 inches, an increase of 82.2%.

The second club tested was a Vokey wedge with a chrome finish. The width of the groove before blasting of this club was 0.051 inches, and the width of the groove after blasting was 0.076 inches, a change of 49.0%.

The third club tested was the Ping wedge. This club is made of typical 17-4PH stainless steel. The width of the groove before blasting of this club was 0.049 inches, and the width of the groove after blasting was 0.072 inches, a change of 56.9%.

The last club tested was the wedge of the invention. The width of the groove before blasting of this club was 0.030 inches, and the width of the groove after blasting was 0.036 inches, a change of 20.0%.

Table 1 below summarizes these results. [table 1]

Club Width before blasting (inch) Width before blasting (inch) Rate of change Rough-finished Vokey wedge 0.045 0.082 82.2% Chrome-finished Vokey wedge 0.051 0.076 49.0% Ping wedge 0.049 0.072 56.9% Wedge of the present invention 0.030 0.036 20.0%

The change in the width of the groove 22 of the club head 1 of the present invention is preferably about 40% or less during the blast test. More preferably, the change in groove 22 is approximately 30% or less during the blast test. Even more preferably, the change in groove 22 is approximately 25% or less during the blast test.

In the development of the present invention, a correlation between wear resistance and material hardness was discovered. A preferred material as the second material is disclosed in US Pat. No. 5,370,750, such as Novotny, which is incorporated herein by reference. US patents such as Novotny describe materials that show a preferred combination of hardness and corrosion resistance.

U.S. patents such as Novotny state that a controlled proportion of carbon and chromium provides significant hardness and corrosion resistance. Carbon contributes to high hardness so that the carbon content is at least about 1.40% and more preferably at least about 1.50%. Since too much carbon adversely affects the corrosion resistance, the carbon content is about 1.75% or less, preferably about 1.65% or less. In the best results, the carbon content of the material is about 1.58% to 1.63%. The chromium content effective for corrosion resistance is at least about 13.5%, preferably at least about 15.5%. If the chromium content is too high, the hardness is adversely affected and the melting treatment temperature is limited to an undesired narrow range. Therefore, the chromium content is about 18.0% or less, preferably about 16.5% or less. Table 2 summarizes the preferred face compositions, which is a copy from Table 1 of US patents such as Novotny.

[Table 2]

Element Wide range (%) Preferred range (%) C 1.40 ~ 1.75 1.50 ~ 1.65 Mn 0.30 ~ 1.0 0.45 ~ 0.60 Si 0.08 (maximum) 0.30 ~ 0.45 P 0.020 (maximum) 0.020 (maximum) S 0.015 (maximum) 0.015 (maximum) Cr 13.5 ~ 18.0 15.5 ~ 16.5 Ni 0.15 ~ 0.65 0.25 ~ 0.45 Mo 0.40 ~ 1.50 0.75 ~ 0.90 V 1.0 (maximum) 0.40 ~ 0.50 N 0.02 ~ 0.08 0.04 ~ 0.06 The rest of the alloy is essentially iron, unlike normal impurities.

Therefore, the second material preferably contains approximately 1.40% to approximately 1.75% carbon and approximately 10.0% to approximately 18.0% chromium. More preferably, the second material contains approximately 1.50% to approximately 1.65% carbon and approximately 15.5% to approximately 16.5% chromium.

The composition of carbon and chromium can be expressed as a ratio. As shown in US patents such as Novotny, the second material preferably has a chromium to carbon ratio of approximately 10: 1 to approximately 11: 1. All percentages mentioned here are weight%.

As mentioned above, wear resistance correlates with the hardness of the material. Therefore, another way to classify the first and second materials depends on their absolute and relative hardness. The first material is harder than the second material. This relationship provides the required face wear resistance and allows the club head to be customized for the golfer's unique swing. This relationship is the opposite of most clubs with face inserts, resulting in a relatively soft face and a relatively stiff body.

Throughout the tests, it was found that a second material with a Rockwell C hardness of about 40 or higher provides adequate face abrasion resistance. More preferably, the face insert 20 has a Rockwell C hardness of about 50 to about 55. To allow workability, the first material preferably has a Rockwell C hardness of about 30 or less.

Since the sole 14 collides with the ground during normal use, the sole 14 also wears. The club head 1 may preferably have a sole insert 30 made of a third material. The third material is harder than the first material. The third material has the same abrasion resistance and composition as described above for the second material. The third material can be about the same as or different from the second material.

Although preferred embodiments of the present invention have been described above, it should be understood that these embodiments are merely examples and do not limit the present invention. As will be apparent to those skilled in the art, various changes can be made in terms of shape and detail without departing from the spirit and scope of the present invention. Therefore, the present invention should not be limited to the embodiments described above, but should be defined only by the claims and their equivalents.

<figref num="1">The perspective view which shows the golf club head of this invention.</figref><figref num="2">The figure which shows the blast test form.</figref><figref num="3">Side view of a known golf club groove before the blast test.</figref><figref num="4">Side view of the groove of the golf club in FIG. 3 after the blast test.</figref>

Code description

1: Golf club head 10: Body 11: Heel 12: Toe 13: Crown 14: Sole 15: Hosel 20: Hitting face 22: Groove 30: Sole insert 50: Groove 100: Club head 102: Face