Patent Application
20080050266
A first example of a low-density alloy for a golf club head in accordance with the present invention is a Ti—Al—V alloy in which titanium (density 4.51 g/cm3), aluminum (density 2.70 g/cm3), and vanadium (density 5.79 g/cm3) are the main compositions (See Table 2).
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The Ti—Al—V alloy (or simply titanium alloy) comprises 84 wt %-94 wt % of Ti, 6.5 wt %-9.5 wt % of Al, and V less than 1.5 wt %. The titanium alloy has a density smaller than 4.40 g/cm3. Preferably, the titanium alloy comprises 91 wt % of Ti, 8 wt % of Al, and 1 wt % of V (Ti-8Al-1V, see Table 2).
As compared to the conventional Ti-6Al-4V alloy, the density of the titanium alloy in accordance with the present invention is reduced and the toughness of the titanium alloy in accordance with the present invention is improved by increasing the amount of aluminum, thereby obtaining the required low-density property. Further, by reducing the amount of vanadium, the flowability and the auxiliary degassing effect during casting are improved without adversely affecting the mechanical properties of the titanium alloy. The Ti—Al—V alloy in accordance with the present invention can be used to manufacture component(s) of a golf club head, such as a main body, a striking plate, a cover, and/or a weight member, preferably the striking plate.
Since the density (4.40-4.34 g/cm3) of the Ti-8Al-1V alloy in accordance with the present invention is lower than that (4.42 g/cm3) of the conventional Ti-6Al-4V alloy, the Ti-8Al-1V alloy in accordance with the present invention can be used in the components of the golf club head to reduce the overall weight of the golf club head without adversely affecting the mechanical properties. As a result, the center of gravity of the golf club head can be adjusted.
Table 2 shows the second, third, fourth, and fifth examples of the low-density alloy in accordance with the present invention, in which trace elements (such as Mo less 1.2 wt %, Cr less than 1.2 wt %, Fe less than 0.6 wt %, Si less than 0.6%, and B less than 1.0 wt %) are selectively added into the Ti-8Al-1V alloy.
By adding an appropriate amount of molybdenum (Mo), uniformly distributed carbonide can be precipitated from the alloy and the heat-resisting property is improved, reducing heat crack during welding of the alloy, improving the hardening property, and improving the strength at high temperature. By adding an appropriate amount of chromium (Cr), the rust-resisting property is improved and the life of the golf club head is prolonged. By adding an appropriate amount of iron (Fe), the alloy has improved plasticity for processing. By adding an appropriate amount of silicon (Si), the flowability of the molten metal is improved. By adding an appropriate amount of boron (B), the structure of the alloy is stable at high temperature, providing improved anti-oxidation property, improved toughness, and improved plasticity, thereby improving the mechanical properties of the alloy.
In the alloy of the second example 0.25 wt %-0.5 wt % of Mo is added, in the alloy of the third example 0.4 wt %-0.6 wt % of Cr is added, in the alloy of the fourth example 0.2 wt %-0.4 wt % of Fe is added, and in the alloy of the fifth example 0.25 wt %-0.35 wt % of Si is added. In addition, B less than 1.0 wt % can be added into the alloy in accordance with the present invention for forming a golf club head. The Ti—Al—V alloys in the second through fifth examples of the present invention can be used to manufacture component(s) of a golf club head, such as the main body, striking plate, cover, and weight member, preferably the striking plate.
The golf club head manufactured with the above five examples of Ti—Al—V-based alloy added with trace elements such as Mo, Cr, Fe, Si, and/or B has a density smaller than that of Ti-6Al-4V alloy, and has an elongation higher than that of Ti-6Al-4V alloy. The elongation E % (elastic deforming property) of the low-density Ti—Al—V alloy in accordance with the present invention is increased within the elastic limit of the material. This improved elastic deforming property allows greater elastic deforming extent during striking, thereby improving the hitting performance. Further, use of the low-density Ti-8Al-1V alloy allows reduction in the overall weight of the golf club head. Further, using the low-density Ti-8Al-1V alloy to manufacture component(s) (such as the main body, cover, striking plate, and/or weight member) of the golf club head allows adjustment of the center of gravity of the golf club head. As a result, the volume of the golf club head can be maximized without increasing the weight of the golf club head. The scope of the sweet spot of the golf club head is increased and the rate of the ball-hitting failure is reduced. Further, the design flexibility of the golf club head is increased.
As given in Tables 3 and 4, a sixth example of the low-density alloy in accordance with the present invention is illustrated. In comparison with the first to fifth examples, the low-density alloy of Ti-7.5Al-0.05V-0.02Si-0.06B4C comprises 7.2 wt %-7.8 wt % of Al, 0.02 wt %-0.06 wt % of V, 0.22 wt % of Si, 0.06 wt % of B4C, 0.06 wt % of Fe, 0.04 wt % of C, 0.01 wt % of N, 0.21 wt % of O and the balance is essentially Ti. The mechanical properties of Ti-7.5Al-0.05V-0.02Si-0.06B4C are similar to those of Ti-6Al-4V, but the density of Ti-7.5Al-0.05V-0.02Si-0.06B4C is 4.32 g/cm3 is less than Ti-6Al-4V (4.42 g/cm3). In cannon testing, a striking plate made from Ti-7.5Al-0.05V-0.02Si-0.06B4C of the present invention has passed the 3,000-hit test. Accordingly, the club head members made from Ti-7.5Al-0.05V-0.02Si-0.06B4C can further reduce the weight of the golf club head, and lower a specific center of gravity of the golf club head. Other golf club head members suitable for reducing weight are club head body, crown plate, striking plate and club weight member.
While the principles of this invention have been disclosed in connection with specific embodiments, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims.
