Golf club head and manufacturing method thereof

Abstract

The invention provides a method for manufacturing a golf club head. The method comprises the following steps: providing an alloy of 0.8 + / -0.2 wt% of silicon, 1.0 + / -0.2 wt% of manganese, 1.0 + / -0.2 wt% of chromium, 0.3 + / -0.2 wt% of molybdenum, 0.25 to 0.30 wt% of carbon, 0.8 to 1.5 wt% of nickel, 0 to 0.03 wt% of phosphorus, 0 to 0.03 wt% of sulfur, unavoidable trace elements and a balance of iron; performing a casting step using the alloy to form a golf club head; performing water mist cooling on the golf club head; and carrying out heat treatment on the golf club head after water mist cooling, wherein the heat treatment step comprises carrying out heat treatment for 0.5-1.5 hours in an environment of 900 DEG C + / -20 DEG C and carrying out heat treatment for 2-4 hours in an environment of 200 DEG C + / -20 DEG C. When the thickness of the golf club head manufactured by the method is reduced to 1.9 + / -0.1 mm, the golf club head still has the Vickers hardness of 580 + / -10 and the toughness of greater than 3.0 kg-m, and has the characteristics that the ball hitting characteristic time can be prolonged and the durable blasting frequency is greater than 2500.

Description

Technical Field

[0001] This invention relates to a golf club head and a method for manufacturing the same, and more particularly to a cast golf club head and a method for manufacturing the same. Background Technology

[0002] In existing golf head designs, to improve hitting distance, the main approaches are: (1) reducing the thickness of the striking surface, primarily by increasing the strength of the striking surface material; and (2) designing a striking surface with uneven thickness. In terms of physical impact, increasing the hardness (strength) of the striking surface can enhance the rebound force; however, the above methods will reduce elastic impact, resulting in energy loss and reduced contact time. Therefore, increasing the surface hardness of low-strength materials will help improve the rebound force, resulting in a better hitting distance.

[0003] Please refer to Figure 1 As shown, Figure 1 This diagram shows the material properties of commonly used golf club iron heads. Figure 1 Currently, commonly used golf iron heads are primarily developed using low-alloy steel and precipitation-hardening stainless steel, with strengths ranging from 220 to 260 ksi and elongation between 6% and 10%, as shown in area A of Figure 1. However, for high-strength hitting face materials, a decrease in the thickness of the hitting face will alter its impact characteristics and stress field. Simply considering material strength, or a hitting face design with an outer hard and inner soft or vice versa, while improving the impact characteristic time, may not necessarily meet the requirements for the number of shots.

[0004] Existing technology designs the clubhead structure to be stiff on the outside and soft on the inside, and reduces the stiffness of the shaft to achieve room-temperature adjustment characteristics. However, as the stiffness decreases, the characteristic time (CT) also decreases. Furthermore, the thickness of the batting face needs to be 2.2 to 2.4 mm to ensure sufficient characteristic time and a high number of impacts.

[0005] Therefore, it is necessary to provide golf club heads and their manufacturing methods to solve the problems existing in the prior art. Summary of the Invention

[0006] One objective of this invention is to provide a golf club head and its manufacturing method, which differs from existing material development concepts. Under the condition of meeting strength requirements, it improves the impact toughness of the alloy, so that when the thickness of the golf club head's striking face material is reduced from 2.4 mm to 1.8 mm (especially at a thickness of 1.9 ± 0.1 mm), it has the characteristics of high hardness (Vickers hardness (Hv) of 580 ± 10) and high toughness (greater than 3.0 kg-m), and can improve the characteristic time of impact and the durability of more than 2500 shots.

[0007] Another object of the present application is to provide a golf club head and a manufacturing method thereof, such that a thickness of a ball striking face of the golf club head is 1.9±0.1 mm, a ball impact characteristic time is greater than 270 μsec, and a number of hits is greater than 2500.

[0008] To achieve the above object, the present application provides a manufacturing method of a golf club head, comprising the steps of: providing an alloy, wherein the alloy is composed of 0.8±0.2 wt% of silicon, 1.0±0.2 wt% of manganese, 1.0±0.2 wt% of chromium, 0.3±0.2 wt% of molybdenum, 0.25 to 0.30 wt% of carbon, 0.8 to 1.5 wt% of nickel, 0 to 0.03 wt% of phosphorus, 0 to 0.03 wt% of sulfur, inevitable trace elements, and a balance of iron; performing a casting step using the alloy to form a cast golf club head; performing a water mist cooling step on the cast golf club head; and performing a heat treatment step on the cast golf club head after the water mist cooling step, wherein the heat treatment step comprises a heat treatment at 900℃±20℃ for 0.5 to 1.5 hours and a heat treatment at 200℃±20℃ for 2 to 4 hours.

[0009] In an embodiment of the present application, the cooling rate of the water mist cooling step is between 800 to 1000℃ / min.

[0010] In an embodiment of the present application, the casting step is a lost wax casting step.

[0011] Further, the present application also provides a golf club head manufactured by the above method.

[0012] In an embodiment of the present application, the Vickers hardness (Hv) of the ball striking face of the golf club head is 580±10.

[0013] In an embodiment of the present application, the toughness of the ball striking face of the golf club head is 3.5±0.5 kg-m.

[0014] In an embodiment of the present application, the thickness of the ball striking face of the golf club head is 1.9±0.1 mm.

[0015] In an embodiment of the present application, the ball impact characteristic time of the golf club head is greater than 270 μsec.

[0016] In an embodiment of the present application, the number of hits of the golf club head is greater than 2500.

[0017] Compared with the prior art, the present application provides a cast golf club head, the club head alloy steel component composition can be 0.8±0.2wt% silicon, 1.0±0.2wt% manganese, 1.0±0.2wt% chromium, 0.3±0.2wt% molybdenum, 0.25-0.30wt% carbon, 0.8-1.5wt% nickel, 0-0.03wt% phosphorus, 0-0.03wt% sulfur, inevitable trace elements and a balance of iron. The above alloy composition head is precisely cast and matched with water mist rapid cooling, thereby obtaining fine grain structure. After the heat treatment condition of the present application, the club head striking surface has the characteristics of high hardness and high toughness. When the club head of the present application is applied to a golf club, the limit thickness of the striking surface can reach 1.9±0.1mm, and has the effect of improving the ball striking characteristic time (CT) and the number of endurance shots.

[0018] In order to make the above content of the present application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are described in detail as follows: BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a commonly used golf head iron head material property diagram.

[0020] Figure 2 It is a flowchart of the manufacturing method of the golf club head of the embodiment of the present application.

[0021] Figure 3 It is a striking surface microstructure diagram after the cast golf iron head of the alloy B of the present application is subjected to (A) capping heat preservation, (B) natural air cooling, (C) water mist cooling, 902℃ / 30min high temperature treatment, and then 194℃ / 120min low temperature treatment.

[0022] Figure 4 It is an impact toughness distribution diagram of the comparative example and the embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the above content of the present application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are described in detail as follows. Furthermore, the directions mentioned in the present application, such as up, down, top, bottom, front, back, left, right, inner, outer, side, periphery, center, horizontal, transverse, vertical, longitudinal, axial, radial, uppermost layer or lowermost layer, are only reference directions of the accompanying drawings. Therefore, the directions used are used to illustrate and understand the present application, not to limit the present application.

[0024] As used herein, reference to a numerical range for a variable is meant to include all values from and including the lower to the upper bound of the range. Thus, a variable having a value selected from the range of 0 to 1, is meant to include a value of 0, 0.1, 0.01, 0.001, etc. and a value of 1, 0.9, 0. 99, 0.999, etc. Similarly, a variable having a value selected from the range of 0 to 10, is meant to include a value of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 0.0, 0.1, 0.01, 0.001, etc. and a value of 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, etc.

[0025] Golf is a game played with clubs to hit a ball into a hole on a course designed with specific features and obstacles (e.g. tree areas, long and short grass areas, sand traps, water hazards, etc.). However, various clubs have been developed for different obstacles and purposes. For example, a complete set of 14 clubs includes 3 to 5 wood clubs (driver and fairway wood), 8 to 10 iron clubs (iron, pitching wedge or sand wedge), and 1 putter.

[0026] Wood clubs are mainly used for long distance shots and usually have the largest club head volume and the longest shaft. They have been developed to be larger and lighter to increase the effective hitting area and the miss rate. The main materials are titanium alloy and high-strength stainless steel, or a combination of different materials. Iron clubs are used for various short and medium distance shots and are mainly designed for accurate distance and direction control to overcome the obstacles on the course. Iron clubs have different loft angles to control the hitting distance. The development trend is to expand the sweet spot, new materials and composite structures. The main materials are stainless steel, alloy steel and soft iron. In recent years, to increase the hitting distance, high-strength alloy steel has been used by reducing the thickness of the hitting face to have a high ball characteristic time (CT), which is also one of the development trends. Putters are used for pushing the ball into the hole on the green and usually have the shortest shaft and the smallest club head. The main performance is the stability of the rolling ball. To reduce the rotation of the hit, the design of the center of gravity of the club head and the aesthetic design are mainly focused on, and the commonly used materials are stainless steel, aluminum alloy or soft iron.

[0027] According to the USGA specification, golf clubs are mainly divided into wood clubs, iron clubs and putters according to their shape and purpose of use.

[0028] Wood club exterior specifications: USGA specifies 7 parts of the club head, including: top cover, bottom, hitting face, root, head, shaft, and groove. The hitting face height is specified as 2.8 inches, the front height must be greater than the back height, and the front-back distance must be less than 5 inches; the hitting face width is specified as 5 inches, and the front and back heights are specified as 2.8 inches and 0.875 inches, respectively. The wood club also has a specification that the shaft vertical line back size cannot be greater than 0.625 inches. In addition, the opening wood club has special specifications for its volume and moment of inertia; the volume specification is 460 cm 3 (allowable error is 10 cm 3 ). The moment of inertia specification is 5900 g / cm 2 (allowable error is 100 g / cm 2 ). In addition, the wood club head ball head performance also specifies the characteristic time, mainly to specify the contact time when hitting the ball, which means that the contact time between the golf ball and the golf club head cannot exceed 239 microseconds (the maximum allowable error is 257 microseconds).

[0029] Iron clubs are mainly specified for their exterior dimensions (angles), with a height limit of 2.8 inches, a front height that must be greater than a back height, and a front-back size that must be less than 5 inches; the hitting face width is also limited to 5 inches, the back height is limited to 0.875 inches, and the shaft vertical line back size cannot be greater than 0.625 inches.

[0030] The putter exterior specification is that the hitting face height is 2.5 inches, the width must be greater than the front-back length, and the maximum specification is 7 inches, the hitting face width must be greater than 2 / 3 of the front-back length and greater than 1 / 2 of the width, and there is a deflection design, which specifies the 5-inch size of the front end of the shaft, which can be designed to be curved.

[0031] In addition, in the USGA specification, the club hitting face of the golf ball (the position of contact with the ball) must be of a single material.

[0032] The present application proposes a golf club head with a hitting face limit thickness of 1.9±0.1 mm, which has the characteristics of improving the ball hitting characteristic time (CT) and high durability of the number of hits.

[0033] Please refer to Figure 2Figure 1 is a flowchart showing a manufacturing method of a golf club head according to an embodiment of the present application. The present application provides a manufacturing method of a golf club head, comprising the following steps: (S11) providing an alloy, wherein the alloy composition comprises: 0.8±0.2 wt% silicon, 1.0±0.2 wt% manganese, 1.0±0.2 wt% chromium, 0.3±0.2 wt% molybdenum, 0.25 to 0.30 wt% carbon, 0.8 to 1.5 wt% nickel, 0 to 0.03 wt% phosphorus, 0 to 0.03 wt% sulfur, inevitable trace elements, and the balance of iron; (S12) performing a casting step using the alloy to form a cast golf club head; (S13) performing a water mist cooling step on the cast golf club head; (S14) performing a heat treatment step on the water mist cooled cast golf club head, wherein the heat treatment step comprises a heat treatment at 900℃±20℃ for 0.5 to 1.5 hours and a heat treatment at 200℃±20℃ for 2 to 4 hours.

[0034] The above alloy composition is cast (e.g., investment shell lost-wax precision casting) and then rapidly cooled with water mist to obtain a fine grain structure. The heat treatment according to the present application (heat treatment at 900℃±20℃ for 0.5 to 1.5 hours and heat treatment at 200℃±20℃ for 2 to 4 hours) further improves the hardness and toughness of the striking face of the golf club head. When the golf club head is used in a golf club, the striking face can have a thickness of 1.9±0.1 mm and can have improved characteristics of ball impact time (CT) and durability of more than 2500 shots.

[0035] The approximate effects of each component are as follows:

[0036] Carbon (C): Carbon is an essential element for general steel materials. It is used to precipitate carbides and to avoid changes in casting characteristics by avoiding a temperature range in which solid and liquid phases coexist.

[0037] Manganese (Mn) and Silicon (Si): When silicon is added to the composition alloy of the present invention, it is advantageous to prevent the formation of pores, to increase the shrinkage effect, and to increase the fluidity of the steel liquid, thereby increasing the castability of the alloy castings; manganese is easily coexistent with iron, can increase the strength and hardness of carbon, and is easily combined with sulfur, can be used as a desulfurizer to improve the hot brittleness of the alloy, increase the hardness, ductility, toughness and wear resistance, and manganese can also remove the oxides in the alloy. By adjusting the manganese / carbon ratio, on the one hand, the strength of the steel can be prevented from decreasing, and on the other hand, the toughness and weldability of the steel can be improved. For every increase of 0.01% manganese content, the tensile strength can be increased by about 150 psi. However, the increase of manganese content will be detrimental to the weldability of the steel. Therefore, the present invention designs the carbon content in the composition alloy of the cast iron to be controlled at 0.25 to 0.30% by weight, the silicon content to be controlled at 0.8±0.2% by weight, and the manganese content to be controlled at 1.0±0.2% by weight (for example, based on the total weight of the composition alloy of the golf club head being 100 wt%), which will help to improve the castability of the alloy castings, and improve the hardness and toughness of the steel.

[0038] Chromium (Cr): Chromium added to steel can significantly improve the oxidation resistance of steel and increase the corrosion resistance of steel. The addition of chromium to cast iron can increase the hardness and improve the wear resistance. The present invention designs the chromium content in the cast iron to be 1.0±0.2% by weight to improve its mechanical properties. However, too high a chromium content will result in the presence of some ferrite, which is not conducive to the characteristics of mechanical properties.

[0039] Nickel (Ni): Nickel is added as an alloying element in the steel industry to increase the bending strength and hardness of steel. The present invention designs the nickel content in the cast iron to be 0.8 to 1.5% by weight, which can make the structure uniform and increase the density.

[0040] Molybdenum (Mo): Molybdenum forms hard and stable carbides in the alloy. Molybdenum can increase the strength and corrosion resistance of the steel. The present invention designs the molybdenum content in the cast iron to be 0.3±0.2% by weight, which can increase the strength of the cast iron and its ability to resist rust and acid.

[0041] Phosphorus (P): Phosphorus has a very good effect on increasing the hardness and strength of steel, but the ductility and toughness are relatively decreased. The present invention designs the phosphorus content in the cast iron to be 0 to 0.03% by weight, which can appropriately increase the hardness of the steel while still maintaining appropriate ductility and toughness.

[0042] Sulfur (S): Appropriate amount of sulfur can improve the machinability of the cast iron, making it easier to handle during machining process. However, sulfur in cast iron will form sulfides (mainly iron sulfide, FeS), and excessive sulfides can form on the grain boundaries, affecting the toughness and ductility of the material, making the material brittle, leading to a decrease in toughness and ductility, and easy to crack and break. The presence of sulfur also reduces the corrosion resistance of cast iron, especially in acidic environments, because sulfides will become active points for corrosion, promoting the occurrence of localized corrosion. The present invention designs the content of sulfur to be 0 to 0.03% by weight, and low content of sulfur will not significantly affect the overall mechanical properties of the cast iron, and still maintain good strength and hardness.

[0043] The striking face of the ball head blank of the present invention is designed with uniform thickness, with a thickness of between 1.8 and 2.0 mm. The main component table of the comparative examples and examples of the present invention is shown in Table 1. In Table 1, Examples 1 to 5 use the alloy composition of the present invention, Comparative Examples 1 and 2 are prior art A steel and B steel, and the alloy composition of Comparative Example 3 is a commercial 8620 steel.

[0044] Table 1: Main component table of golf iron heads of comparative examples and examples of the present invention (wt%)

[0045] Number Alloy Number Fe Ni Cr Mo C Si Mn P S Example 1 Alloy A Balanced amounts 1.48 0.96 0.45 0.27 0.62 1.11 0.03 0.03 Example 2 Alloy B Balanced amounts 1.21 1.04 0.38 0.28 0.65 1.06 0.03 0.02 Example 3 Alloy C Balanced amounts 1.08 1.03 0.33 0.28 0.6 1.21 0.03 0.02 Example 4 Alloy D Balanced amounts 0.88 1.04 0.29 0.29 0.63 0.95 0.03 0.03 Example 5 Alloy E Balanced amounts 0.81 0.99 0.25 0.27 0.66 0.99 0.03 0.03 Comparative Example 1 Alloy F Balanced amounts 0.59 1.05 0.33 0.43 0.52 0.78 0.04 0.04 Comparative Example 2 Alloy G Balanced amounts 0.21 0.95 0.25 0.35 0.72 0.81 0.04 0.03 Comparative Example 3 Alloy H Balanced amounts 0.42 0.88 0.21 0.21 0.65 0.66 0.05 0.04

[0046] The golf iron heads of Table 1 are made by shell precision casting, and the casting cooling methods are natural air cooling (cooling rate of 60-120°C / min), cover insulation (cooling rate of 5-30°C / min) and water mist cooling (cooling rate of 800-1000°C / min), etc. Different cooling methods are used to cool to room temperature (e.g. 15 to 35°C), and then demolding and sprue cutting operations are carried out at room temperature. After that, the golf iron head castings are subjected to heat treatment at 900°C±20°C for 0.5 to 1.5 hours (e.g. 902°C / 30 minutes) and low temperature treatment at 200°C±20°C for 2 to 4 hours (e.g. 194°C / 120 minutes). As shown in Table 2, the microstructure of the ball head is tempered martensite structure, Figure 3 Figure 3 The grain size arrangement is shown in Table 2: cover insulation > natural air cooling > water mist cooling. The cast golf ball head is cooled by water mist cooling, and the heat treatment process of the present invention is used to obtain fine grain structure (fine dendritic structure), which has high toughness characteristics and can improve the striking properties of the golf iron head.

[0047] ​In addition, in order to verify the impact value characteristics, the present inventors also conducted impact toughness analysis, which was performed on alloy bars processed into 10 mm x 10 mm x 55 mm, 5R / 2 mm alloy bars. The impact test pieces were subjected to high temperature treatment at 900°C / 30 minutes, and then subjected to heating treatment at 150 to 450°C / 120 minutes. As shown in Table 1. Figure 4 Figure 4 The fine grain data B (the golf head of the alloy B of the embodiment 2 of the present application, which was subjected to water spray cooling to form a fine grain structure) had an impact toughness of about 2.25 kg-m after being subjected to high temperature treatment at 902°C / 30 minutes and being placed in 70°C / 20 minutes oil liquid (oil quenching treatment). The impact toughness value reached 3.60 2.25 kg-m at 200°C tempering treatment. However, at 300°C tempering treatment, the impact toughness decreased to 1.90 2.25 kg-m due to low temperature tempering quenching. Thereafter, the impact toughness continued to increase with the increase of the tempering temperature, reaching the highest point at 450°C. In addition, Figure 4 The coarse grain data B (the golf head of the alloy B of the embodiment 2 of the present application, which was subjected to natural cooling to form a coarse grain structure), and the data F and G (the golf heads of the alloy F and the alloy G of the comparative examples 1 and 2 of the present application, which were subjected to natural cooling to form a coarse grain structure) also showed low impact toughness. In general, the alloy series of the embodiment of the present application had higher impact toughness values. In addition, although higher tempering treatment temperature could result in higher impact toughness values, it would cause the hardness value (material strength) of the alloy to decrease. It should be noted that the present application has the characteristics of high hardness and high toughness, which is mainly due to the low temperature tempering treatment at 200°C±20°C applied to the golf head.

[0048] In addition, in order to verify the effectiveness of the present application, the cast golf iron heads of the alloy compositions (embodiments 1 to 5) and the comparative examples 1 to 3 of the present application were subjected to high temperature treatment at 902°C / 30 minutes, and then subjected to low temperature treatment at 194°C / 120 minutes. The average value of the characteristic time (CT), the hardness value, the number of endurance shots, and the thickness value of the hitting surface of the 6 cast golf iron heads were measured, and the results are shown in Table 2. Table 2 shows that the alloy series of the present application can obtain fine grain structure under water spray cooling parameters; when the thickness of the hitting surface is 1.9±0.1 mm, the ball hitting characteristic time is greater than 270 microseconds, the Vickers hardness (Hv) is greater than 570, and the number of shots is greater than 2500 shots.

[0049] Table 2: Average value of characteristic time CT, strength value, and number of endurance shots of the embodiments and comparative examples of the present application

[0050]

[0051] ​It should be noted that those skilled in the art can make various modifications to the present application without departing from the spirit and scope of the present application, and the above description is only the preferred embodiment of the present application, and does not limit the patent application range of the present application. Any equivalent changes made by using the content of the present application specification and drawings are included in the patent application range of the present application.

Claims

1. A method for manufacturing a golf club head, characterized in that, The method includes the following steps: An alloy is provided, wherein the alloy composition comprises: 0.8 ± 0.2 wt% silicon, 1.0 ± 0.2 wt% manganese, 1.0 ± 0.2 wt% chromium, 0.3 ± 0.2 wt% molybdenum, 0.25 to 0.30 wt% carbon, 0.8 to 1.5 wt% nickel, 0 to 0.03 wt% phosphorus, 0 to 0.03 wt% sulfur, unavoidable trace elements, and a balance of iron; The alloy is used in a casting process to form a cast golf club head; The cast golf club head is subjected to a water mist cooling step; The cast golf club head, after being cooled by water mist, undergoes a heat treatment process, which includes heat treatment at 900℃±20℃ for 0.5 to 1.5 hours and heat treatment at 200℃±20℃ for 2 to 4 hours.

2. The method as described in claim 1, characterized in that, The cooling rate of the water mist cooling step is between 800 and 1000°C / minute.

3. The method as described in claim 1, characterized in that, The casting step is a mold shell dewaxing casting step.

4. A golf club head manufactured by the method as described in any one of claims 1 to 3.

5. The golf club head as described in claim 4, characterized in that, The Vickers hardness Hv of the clubhead striking surface is 580±10.

6. The golf club head as described in claim 4, characterized in that, The toughness of the striking surface of the golf club head is 3.5 ± 0.5 kg-m.

7. The golf club head as described in claim 4, characterized in that, The thickness of the striking face of the golf club head is 1.9 ± 0.1 mm.

8. The golf club head as described in claim 4, characterized in that, The impact time of the golf club head is greater than 270 microseconds.

9. The golf club head as claimed in claim 4, characterized in that, The golf clubhead has a durability rating of more than 2,500 shots.

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