JP4912231B2 - Manufacturing method of golf club head - Google Patents

Description

  The present invention relates to a method for manufacturing a golf club head.

  In recent years, the volume of golf club heads tends to be large. A golf club head having a large volume has a large moment of inertia and a large sweet area. Since the weight of the head is limited, it is preferable that the material of the large head has a high specific strength. From this point of view, a metal such as a titanium alloy is frequently used as the material of the head.

The golf club head has portions such as a face portion, a crown portion, a side portion, and a neck portion. The required characteristics are different for each part. For example, the face portion is a portion where the ball collides, and a particularly high strength is required. Depending on each part of the head, preferred manufacturing methods and materials may exist. In the case of a large-sized head, the thickness of the head tends to be thin, so that the head strength tends to be low. In a large-sized head, since the thickness of the head tends to be thin, the degree of freedom in designing the center of gravity of the head tends to decrease. Especially for large heads, optimization of manufacturing method and material is required. From this point of view, a golf club head has been proposed in which a plurality of members are manufactured by different manufacturing methods and / or materials and welded together. Japanese Patent Application Laid-Open No. 5-317466 discloses a golf club head in which a face side member and a back side member are welded.
JP-A-5-317466

  In general, in the finishing process of head manufacture, the surface of the head is processed smoothly by polishing. In the case of a welded head, a weld bead is generated at the welded portion. A weld bead is a convex part (swell) formed along the welded part. The weld bead formed on the outer surface of the head is removed by polishing.

  In the polishing step, the head is brought into contact with a polishing member that moves at high speed. During this polishing, frictional heat is generated. The head is heated by the frictional heat, and the temperature of the head rises. A long polishing time is required to remove the large convex portion of the weld bead. As the polishing time increases, the frictional heat also becomes excessive.

  The present inventor has obtained a new finding that the durability of the welded head is affected by the temperature rise accompanying frictional heat during polishing. Based on this new knowledge, the present inventor has found a technique capable of improving the durability of the head based on an unprecedented technical idea.

  An object of the present invention is to provide a manufacturing method capable of improving the durability of a welded head.

  A golf club head manufacturing method according to the present invention includes a welding process in which a metal other member is welded to a metal head body, and a bead polishing process in which a weld bead generated by the welding is polished by a polishing member. . In the bead polishing step, the relative speed of the polishing member with respect to the head is set to 66 (km / h) or more and 120 (km / h) or less. Preferably, the welding is laser welding.

  Preferably, the head body and the other member are made of a titanium alloy. Preferably, at least one of the other members is a thin member having a thickness of 0.1 mm to 1.2 mm.

  Preferably, the thin member is made of a β-type titanium alloy.

  Preferably, the thin member constitutes a crown portion of the head.

  In a head having a welded portion, a decrease in head strength due to frictional heat during polishing can be suppressed.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 is a perspective view of a golf club head 2 manufactured according to an embodiment of the present invention, FIG. 2 is a view of the head 2 viewed from the crown side, and FIG. 3 is III-III in FIG. It is sectional drawing along a line. As shown in FIG. 3, the head 2 has a hollow structure.

  The head 2 is a so-called wood type golf club head. The head 2 includes a face portion 4, a crown portion 6, a sole portion 8, a side portion 10, and a neck portion 12. The neck portion 12 is provided with a shaft hole 14 for inserting and bonding the shaft.

  The head 2 is made of metal. The head 2 is formed by welding a plurality of members. Specifically, the head 2 is formed by welding a head main body 16, a crown member 18, and a face member 20. 1 and 2, a wavy line k1 is a boundary between the crown member 18 and the head body 16. This boundary k1 is equal to the contour line of the crown member 18. 1 and 2, a wavy line k2 is a boundary between the face member 20 and the head body 16. The boundary k2 is equal to the contour line of the face member 20. At the boundary k1, the outer surface of the head 2 is smoothly continuous. At the boundary k2, the outer surface of the head 2 is smoothly continuous.

  The crown member 18 is made of a titanium alloy. The crown member 18 constitutes a part of the outer surface of the head. The crown member 18 constitutes the crown portion 6. The crown member 18 constitutes a part of the crown portion 6. As shown in FIG. 3, the crown member 18 is a plate-like member. The crown member 18 may constitute the entire crown portion 6.

  The face member 20 is made of a titanium alloy. The face member 20 constitutes a part of the outer surface of the head. The face member 20 constitutes a part of the face portion 4. As shown in FIG. 3, the face member 20 is a plate-like member. The face member 20 may constitute the entire face portion 4.

  The head body 16 is made of a titanium alloy. The head body 16 constitutes a part of the outer surface of the head. The head body 16 constitutes a part of the face part 4, a part of the crown part 6, the whole sole part 8, the whole side part 10 and the whole neck part 12.

  As described above, the head 2 is formed by welding the metal other member to the metal head main body 16. In the present embodiment, these other members are the crown member 18 and the face member 20. The other member constitutes the outer surface of the head. In this embodiment, there are two other members. The number of other members may be one, or three or more. The head of the present invention may include a non-metallic member.

  The head 2 has a thin member as another member. A thin member is a member having a thickness of 0.1 mm to 1.2 mm. In the head 2, the crown member 18 is a thin member. The face member 20 is not a thin member. The thickness of the face member 20 exceeds 1.2 mm.

  The manufacturing process of the head 2 will be described below. First, each of the head main body 16, the crown member 18, and the face member 20 is manufactured. These manufacturing methods are not limited. Next, a welding process is performed. In the welding process, the head body 16 and the crown member 18 are welded, and the head body 16 and the face member 20 are welded. FIG. 4 is a cross-sectional view of the head 2 immediately after the welding process. By welding, a weld bead b1 is generated at the boundary k1. The weld bead b1 protrudes on the outer surface of the head. By welding, a weld bead b2 is generated at the boundary k2. The weld bead b2 protrudes on the outer surface of the head.

  Next, the head is heat-treated as necessary. Next, a polishing process is performed. The polishing process includes a bead polishing process and a final polishing process. In the bead polishing process, the weld bead is shaved and removed. In the final polishing step, the entire outer surface of the head 2 is polished. Of the polishing steps, the step of polishing the weld bead is referred to as a bead polishing step in the present application. By the polishing process, the outer surface of the head 2 becomes smooth. The aesthetic appearance of the head 2 is improved by the polishing process, and the head 2 having a commercial value is obtained. Finally, the outer surface of the head is painted as necessary.

  In the polishing process, a polishing machine is used. FIG. 5 is a perspective view showing the polishing machine 22 according to one embodiment. The polishing machine 22 is a so-called belt sander type polishing machine. The polishing machine 22 includes a polishing member 24, a driving roller 26, a driven roller 28, and a motor 30. The drive roller 26 is rotated by a motor 30. The rotational speed of the drive roller 26 is variable. The outer peripheral surface of the drive roller 26 is made of rubber.

  The polishing member 24 is a polishing belt. This polishing belt is endless. The abrasive belt is formed by adhering abrasive particles to the surface of a substrate such as cloth or paper. The width of the polishing member 24 is, for example, about 50 mm to 100 mm.

  FIG. 6 is a schematic configuration diagram showing the polishing member 24, the driving roller 26, and the driven roller 28 in the polishing machine 22. The polishing member 24 is stretched between the driving roller 26 and the driven roller 28. A predetermined tension acts on the polishing member 24. This tension is adjusted by the distance between the driving roller 26 and the driven roller 28. When the driving roller 26 is rotated by the motor 30, the polishing member 24 is rotated. The rotation of the driving roller 26 is transmitted to the driven roller 28 by the polishing member 24. As a result, when the driving roller 26 rotates, the polishing member 24 rotates and the driven roller 28 also rotates. In FIG. 6, the rotation directions of the driving roller 26 and the driven roller 28 are clockwise. In FIG. 6, the polishing member 24 also rotates clockwise. The arrows in FIG. 6 indicate the rotation direction of the polishing member 24.

  Polishing is performed by pressing the head 2 against the rotating polishing member 24. The head 2 is pressed against a region where the driving roller 26 and the polishing member 24 are in contact (for example, a region indicated by A1 in FIG. 6). A human (abrasive craftsman) presses the head 2 against the polishing member 24. Since the outer peripheral surface of the drive roller 26 is made of rubber, it can be compressed and deformed. Therefore, the polishing member 24 and the head 2 can be in surface contact.

  In the bead polishing step, the weld bead b1 and the weld bead b2 are polished. In the final polishing process, the entire head 2 is polished. The contact position between the head 2 and the polishing member 24 is sequentially changed until the entire surface is polished.

In the present invention, the relative speed V1 of the polishing member 24 with respect to the head 2 is defined. In the present embodiment, the head 2 being polished does not substantially move. Therefore, in the present embodiment, the relative speed V1 is a moving speed of one point on the polishing member 24. The relative speed V1 can be calculated from the rotation speed F1 of the drive roller 26 and the radius R1 of the drive roller 26. The relative speed V1 is obtained by the following formula.
V1 = 2 × R1 × π × F1

  In the general-purpose polishing machine 22, the radius R1 of the roller with which the head abuts is about 100 mm to 250 mm.

  By welding, the weld bead b1 and the weld bead b2 are scraped off. Furthermore, fine irregularities on the outer surface of the head 2 are smoothed by polishing. As FIG. 4 shows, the weld bead protrudes more than other portions. Therefore, the grinding process for removing the weld bead (bead grinding process) has an extremely large amount of grinding than the grinding of other parts. The bead polishing process requires time and effort.

  Due to frictional heat during polishing, the head 2 being polished is heated to a high temperature. The heated head surface is easily oxidized. The oxide film on the outer surface of the head can be removed by polishing, but the oxide film on the inner surface of the head remains without being removed. With this oxide film, the metal becomes hard and brittle, and cracks are likely to occur. From this viewpoint, it is preferable that the temperature rise due to polishing is suppressed.

  Furthermore, the temperature rise due to polishing can change the crystal structure of the metal. When the temperature exceeds the solution temperature, the crystal structure can change. The frictional heat is generated only at the contact portion between the polishing member and the head. Therefore, the temperature rise due to frictional heat is significant at this contact portion. The temperature rise due to frictional heat is accompanied by a temperature distribution.

  As described above, the polishing time tends to be long in the bead polishing process. In the polishing of the weld bead, more frictional heat is likely to be generated than in the polishing of other portions. The temperature in the vicinity of the weld bead tends to be higher than the temperature in other portions. In polishing the weld bead, a narrow region is intensively polished. Due to this intensive polishing, a narrow region is locally heated and a large temperature difference can occur. Due to this temperature difference, a portion where the metal structure has changed due to frictional heat (modified portion) and a portion where the metal structure has not changed due to frictional heat (unmodified portion) can occur. The coexistence of the modified portion and the unmodified portion can reduce the strength of the head. Since the crystal structure changes at the boundary between the modified portion and the unmodified portion, the strength of the head can be lowered. From the viewpoint of improving the strength, it is preferable that the change in crystal structure is small.

  In the present invention, it has been found that the strength can be improved by defining the relative speed V1. By setting the relative velocity V1 to 120 (km / h) or less, the change in crystal structure can be suppressed and the strength can be improved. In this respect, the relative speed V1 is preferably 115 (km / h) or less, and more preferably 112 (km / h) or less. By setting the relative speed V1 to 66 (km / h) or more, an excessive polishing time is suppressed, and the finish (smoothness) after polishing is improved. In this respect, the relative speed V1 is preferably equal to or greater than 70 (km / h), and more preferably equal to or greater than 73 (km / h). For example, when the radius R1 of the drive roller 26 is 175 mm, it is preferable that the rotation of the drive roller 26 is polished at a speed of about 1000 rpm to about 1800 rpm.

  From the viewpoint of suppressing the modification of the crystal structure in the thin member, it is preferable that the maximum temperature of the thin member in the bead polishing step is lower than the solution temperature of the metal used in the thin member. The solution temperature of the β-type titanium alloy suitable as a thin member is in the range of 700 ° C to 800 ° C. From the viewpoint of suppressing the modification of the crystal structure, it is preferable that the maximum temperature reached by the thin member in the bead polishing step is less than 700 ° C.

  Conventionally, the relative speed V1 has been performed at about 130 (km / h) or more and 170 (km / h) or less. As described above, the bead polishing process requires an extremely large amount of polishing and much time and labor as compared with polishing of other portions. For this reason, conventionally, polishing of the weld bead has been determined simply from the viewpoint of productivity. That is, in the bead polishing process, conventionally, the viewpoint that “if the relative speed V1 is small, the working time becomes excessive, and if the relative speed V1 is large, the metal is melted and the workability is deteriorated or the polishing failure occurs”. The relative speed V1 was determined. That is, conventionally, in the bead polishing process, the relative speed V1 is set as high as possible within a range in which metal melting and poor polishing do not occur. The present invention is based on a technical idea completely different from the conventional technical idea.

  If the change in the crystal structure from the modified portion to the unmodified portion is continuous, the head strength is hardly lowered. On the other hand, if the change in the crystal structure from the modified portion to the unmodified portion is discontinuous, the head strength is significantly reduced.

  The degree of change in the crystal structure is related to the thickness of the head. The thinner the part, the higher the cooling efficiency by atmospheric air. Therefore, the thinner the part, the greater the temperature difference between the friction part and the non-friction part. Accordingly, the thinner the portion, the more easily the crystal structure changes. Therefore, the effect of the present invention is more apparent as the head thickness at the weld bead portion is thinner. From this viewpoint, in the present invention, it is preferable that at least one of the other members is a thin member. From this viewpoint, when the weld bead b1 in the welded portion between the thin member and the head main body is polished, the relative speed V1 is preferably 66 (km / h) or more and 120 (km / h) or less.

  The degree of change in the crystal structure is related to the material of the head. The lower the thermal conductivity, the less heat conduction from the friction part to the non-friction part. The lower the thermal conductivity, the greater the temperature difference between the friction part and the non-friction part. Therefore, the change in the crystal structure tends to be discontinuous as the material has lower thermal conductivity. For example, a titanium alloy has a low thermal conductivity, so that the change in crystal structure tends to be discontinuous. Therefore, the titanium alloy is preferable in that the effect of the present invention can be manifested as compared with stainless steel, aluminum alloy, and the like.

  The performance of the head varies depending on the position of the center of gravity. For example, a head with a low center of gravity is preferable from the viewpoint of increasing the flight distance. A head with a low center of gravity can contribute to a high launch angle and a small amount of backspin. These initial conditions can increase the flight distance.

  By increasing the degree of freedom of the head thickness distribution, the degree of freedom in designing the center of gravity can be increased. For example, a lower center of gravity head can be achieved with a thinner crown and thicker sole. From the viewpoint of increasing the degree of freedom in designing the position of the center of gravity, a head that can have a thin portion while maintaining durability is preferable.

  From the viewpoint of increasing durability against impact at the time of hitting, the thickness of the thin member is preferably 0.1 mm or more, more preferably 0.2 mm or more, and further preferably 0.4 mm or more. From the viewpoint of revealing the effects of the present invention, the thickness of the thin member is preferably 1.2 mm or less, more preferably 1.0 mm or less, further preferably 0.8 mm or less, and further preferably 0.6 mm or less. From the viewpoint of increasing the welding strength between the thin-walled member and the head main body and revealing the effects of the present invention, the thickness of the head main body at the boundary with the thin-walled member is set to the same numerical range as the above-described numerical range of the thin-walled member. Is preferred. That is, the thickness of the head body at the boundary with the thin member is preferably 0.1 mm or more, more preferably 0.2 mm or more, further preferably 0.4 mm or more, and the upper limit is 1.2 mm or less. Preferably, 1.0 mm or less is more preferable, 0.8 mm or less is more preferable, and 0.6 mm or less is still more preferable.

  From the viewpoint of enhancing durability against impact at the time of hitting the ball, the thickness of the face member 20 is preferably 1.6 mm or more, more preferably 1.8 mm or more, and further preferably 2.0 mm or more. From the viewpoint of suppressing an excessive increase in the head weight, the thickness of the face member 20 is preferably 3.5 mm or less, more preferably 3.2 mm or less, and even more preferably 3.0 mm or less. From the viewpoint of increasing the welding strength with the face member 20, the thickness of the head body 16 at the boundary k <b> 2 with the face member 20 is preferably set to the same numerical range as the numerical range of the face member 20.

  The metal head and its parts can be manufactured by casting, forging, pressing or the like. Casting is advantageous in terms of shape flexibility and productivity. However, due to the problem of hot water flow during casting, thin-walled members are difficult to produce by casting. A suitable manufacturing method of the thin-walled member is a manufacturing method of pressing a rolled plate material, for example. From this viewpoint, the thin-walled member is preferably manufactured by forging or pressing, and more preferably manufactured by pressing. In the head 2, the crown member 18 is preferably manufactured by forging or pressing, and more preferably manufactured by pressing a plate material.

  The manufacturing method of the head body 16 is not limited. From the viewpoint of the degree of freedom of shape and productivity, the method of manufacturing the head body 16 is preferably casting.

  The manufacturing method of the face member 20 is not limited. From the viewpoint of increasing the strength, the manufacturing method of the face member 20 is preferably forging or pressing.

  As long as it is a metal, the material of the head body 16 is not limited. Examples of the material of the head body 16 include pure titanium, titanium alloy, stainless steel, aluminum alloy, and maraging steel. Examples of the titanium alloy include those listed in Table 1 below. From the viewpoint of easy casting and high strength, the material of the head body 16 is particularly preferably 6-4 titanium (Ti-6Al-4V).

  As long as it is a metal, the material of the crown member 18 is not limited. Examples of the material of the head body 16 include pure titanium, titanium alloy, stainless steel, aluminum alloy, and maraging steel. From the viewpoints of formability, workability, and strength, the material of the crown member 18 is preferably a β-type titanium alloy, and more preferably Ti-15V-3Cr-3Sn-3Al. Examples of this β-type titanium alloy include β-type titanium alloys described in Table 1 below.

  As long as it is a metal, the material of the face member 20 is not limited. As long as it is a metal, the material of the face member 20 is not limited. Examples of the material of the face member 20 include pure titanium, titanium alloy, stainless steel, aluminum alloy, and maraging steel. From the viewpoint of strength, the face member 20 is preferably made of a titanium alloy. Examples of the titanium alloy include those listed in Table 1 below. The face member 20 may be omitted, and the entire face portion 4 may be integrally formed as a head body.

   As long as it is a metal, the material of a thin member is not limited. Examples of the material of the other member include pure titanium, titanium alloy, stainless steel, aluminum alloy, and maraging steel. From the viewpoint of workability and strength, the material of the thin member is preferably a β-type titanium alloy, and more preferably Ti-15V-3Cr-3Sn-3Al. Examples of this β-type titanium alloy include β-type titanium alloys described in Table 1 below.

  The thin member is not limited to the crown member. The thin member may constitute any part of the head. Preferably, the thin member is a crown member. Thereby, a head with a low center of gravity can be obtained.

  The material of the thin member is preferably a β titanium alloy. Since the β-titanium alloy is excellent in formability, even when the thickness is 0.1 mm or more and 1.2 mm or less, the fitting accuracy with the head body can be improved. Therefore, a head with a low center of gravity bonded with high accuracy can be obtained.

  The welding method is not limited. Examples of the welding method include laser welding, TIG welding, and plasma welding. Laser welding is preferred from the viewpoint of low heat generation during welding and a small weld bead.

  From the viewpoint of suppressing the oxidation of the head surface during welding, welding is preferably performed in an argon atmosphere. The welding method under an argon atmosphere is not limited. As this method, for example, a welding method in which a welding box having an upper opening is used and welding is performed inside the welding box while argon is allowed to flow from the bottom side of the welding box may be employed. When this method is applied to TIG welding, since the arc terminal and the welding rod are inserted from the upper opening, it is necessary to enlarge the upper opening. If the upper opening is large, the argon concentration in the atmosphere tends to decrease. On the other hand, in laser welding or plasma welding, the upper opening can be made small. Therefore, laser welding or plasma welding is preferable from this viewpoint.

  Thus, welding can be performed in an atmosphere of an inert gas. Thereby, the surface oxidation by the heating at the time of welding can be suppressed to the minimum. On the other hand, in the polishing process, it is difficult to work in an inert gas atmosphere due to the large size of the polishing machine. According to the present invention, surface oxidation during polishing can be effectively suppressed in polishing in air.

  The temperature of the welding location is higher than the temperature at the time of polishing. For this reason, in the technical common sense of those skilled in the art, it was considered that the welding process was larger than the polishing process with respect to the influence of heating. However, the present inventor has paid attention to the fact that the time required for welding is extremely short compared to the extremely long bead polishing time. The present inventor has found that the amount of heat given to the head is excessive in the bead polishing process compared to the welding process. Also, since the welding process takes time, it has been found that the time for high temperature is large. The present inventor has found that the bead polishing process can greatly affect the head strength. The inventor has surprisingly found that heating in the bead polishing process can have a greater effect than heating in the welding process.

The abrasive used for the polishing member 24 is not limited. Examples of the abrasive include aluminum oxide, white alundum (high purity Al ₂ O ₃ ), silicon carbide, zirconia and the like. In particular, in the polishing of a titanium alloy, aluminum oxide and white alundum are preferable from the viewpoints of polishing life (durability), polishing properties, and finished state. Aluminum oxide is particularly preferable because it is slightly inferior to white alundum but has excellent finished smoothness and polishing life.

  The particle size of the abrasive is not particularly limited. In polishing for scraping the weld bead, that is, polishing in the bead polishing step, the particle size of the abrasive used for the polishing member 24 is preferably F80 or more and preferably F120 or less. By setting it as F80 or more, the surface does not become too rough, and the surface smoothness after finish polishing can be improved. By setting it as F120 or less, since polishing time is shortened, workability | operativity improves and frictional heat is suppressed. This particle size is a particle size defined in JIS R6001-1998.

  In the final polishing performed after the bead polishing step, the particle size of the abrasive used for the polishing member 24 is preferably F180 or more, and more preferably F240 or less. By setting it as F180 or more, the surface smoothness after grinding | polishing improves. By setting it to F240 or less, the polishing time can be shortened.

  The polishing machine that can be used in the present invention is not limited. A polishing machine widely used for polishing a golf club head can be suitably used. This general-purpose polishing machine is a belt sander type polishing machine. As this general-purpose polishing machine, there are a sitting-type polishing machine and a standing-type polishing machine. In a sitting type polishing machine, an operator performs polishing work while sitting on a chair or the like. In the standing type polishing machine, the worker performs the polishing work while standing. The above-described polishing machine in FIG. 5 is a sitting type polishing machine. In addition, a handy type polishing machine, a sealed large type polishing machine, or the like can be used.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
The head according to Example 1 was the same as the head 2 shown in FIG. The head body was produced by lost wax precision casting. The material of the head main body was 6-4 titanium (Ti-6Al-4V). The crown member was produced by pressing a plate material. The material of the crown member was Ti-15V-3Cr-3Sn-3Al manufactured by Kobe Steel. The thickness of the crown member was 0.8 mm. The face member was produced by pressing a plate material. The material of the face member was SP700 made by JFE Steel. The head body and the crown member were welded by laser welding. The head body and the face member were welded by laser welding. Next, a polishing process was performed. For the polishing process, a polishing machine shown in FIG. 5 was used. First, a bead polishing process was performed. The weld bead was polished by polishing paper provided with No. 80 (F80) abrasive. In the bead polishing process, the rotational speed of the roller was 1400 rpm, and the relative speed V1 was 92 (km / h). Next, a rough polishing process was performed on the entire head. The entire head was roughly polished by polishing paper provided with No. 80 (F80) abrasive. Next, a final polishing process was performed. The entire head was finished and polished by polishing paper provided with abrasive material No. 180 (F180). In this way, a head according to Example 1 was obtained. The specifications and evaluation results of Example 1 are shown in Table 2 below.

[Example 2, Example 3, Comparative Example 1, Comparative Example 2]
A head according to each example was obtained in the same manner as in Example 1 except that the rotation speed and relative speed V1 of the rubber roller in the bead polishing process were set as shown in Table 2.

[Durability test]
A golf club was obtained by attaching a carbon shaft and a grip to the head. This golf club was attached to a swing robot manufactured by True Temper, and a golf ball was hit at a head speed of 55 m / s. The hit point was the sweet spot position. The test was interrupted every 100 strikes and the visual head was observed for damage. The upper limit was 5,000 hits. If damage to the head was confirmed, the test was terminated at that point. The measurement results are shown in Table 2 below. In Example 1, Example 2, Example 3, and Comparative Example 1, no damage was observed after 5,000 hits. In Comparative Example 2, cracks were observed in the welded part after 4000 hits. This crack occurred at a portion where the crown member and the head main body were welded. The crack occurred in a portion near the face of the crown member (portion α surrounded by a one-dot chain line in FIG. 2).

[Workability]
The number of heads that can be polished during one hour was evaluated as workability. The workability evaluation results are shown in Table 2 below. The greater the number of heads, the shorter the time required for the polishing process and the higher the workability.

[Appearance after polishing]
The appearance after the polishing process was visually evaluated. The evaluation results are shown in Table 2 below. In Comparative Example 1, irregularities were confirmed in the bead portion, and polishing was insufficient.

  As shown in Table 2, the examples have higher evaluation than the comparative examples. From this evaluation result, the superiority of the present invention is clear.

  The present invention can be applied to all golf club heads such as a wood type golf club head and an iron type golf club head.

FIG. 1 is a perspective view of a head according to an embodiment of the present invention. FIG. 2 is a view of the head of FIG. 1 as viewed from the crown side. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 4 is a cross-sectional view of FIG. 3 immediately after welding. FIG. 5 is a perspective view showing an example of a polishing machine. 6 is a view showing a roller and a polishing member in the polishing machine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Head 4 ... Face part 6 ... Crown part 8 ... Sole part 10 ... Side part 12 ... Neck part 16 ... Head main body 18 ... Crown member (thin member) )
DESCRIPTION OF SYMBOLS 20 ... Face member 22 ... Polishing machine 24 ... Polishing member 26 ... Drive roller k1 ... Boundary of head main body and crown member k2 ... Boundary of head main body and face member b1, b2 ... weld bead

Claims (4)

A welding process in which other metal members are welded to the metal head body;
A bead polishing step in which a weld bead generated by the welding is polished by a polishing member,
In the bead polishing process state, and are relative speed is 66 (km / h) or more 120 (km / h) or less of the polishing member relative to the head,
The head body and the other member are made of a titanium alloy,
A method for manufacturing a golf club head, wherein at least one of the other members is a thin member having a thickness of 0.1 mm to 1.2 mm.   The method of manufacturing a golf club head according to claim 1, wherein the welding is laser welding. Method of manufacturing a golf club head according to claim 1 or 2 said thin member is made of β-type titanium alloy. Method of manufacturing a golf club head according to any one of claims 1 to 3 in which the thin member constitute the crown of the head.

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