Metal working – Method of mechanical manufacture – Combined manufacture including applying or shaping of fluent...
Reexamination Certificate
1998-07-09
2002-11-19
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Combined manufacture including applying or shaping of fluent...
C164S080000, C164S495000, C473S324000
Reexamination Certificate
active
06481088
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a golf club which has a club head with a face comprising a metallic glass, namely, a so-called amorphous alloy face exhibiting excellent ball hitting properties. More specifically, this invention relates to a golf club which has a club head with a metallic glass face (amorphous alloy face) of desired shape exhibiting excellent strength properties owing to absence of the so-called cold shut which is the region that became amorphous alloy by meeting of the molten metal surfaces.
Various methods for producing amorphous alloys have been proposed. Exemplary such methods include the method wherein a molten metal or alloy in liquid state is solidified by quenching and the resulting quenched metal (alloy) powder is compacted at a temperature below the crystallization temperature to produce a solid of the predetermined configuration having the true density; and the method wherein a molten metal or alloy is solidified by quenching to directly produce an ingot of the amorphous alloy having the predetermined configuration. Almost all amorphous alloy produced by such conventional methods had an insufficiently small mass, and it has been impossible to produce a bulk material which can be used in golf club face by such conventional methods. Another attempt for producing a bulk material is solidification of the quenched powder. Such attempt, however, has so far failed to produce a satisfactory bulk material.
For example, the amorphous alloy produced in small mass have been produced by melt spinning, single roll method, planar flow casting and the like whereby the amorphous alloy in the form of thin strip (ribbon) in the size of, for example, about 200 mm in the strip width and about 30 &mgr;m in the strip thickness are produced. Use of such amorphous alloys for such purposes as the core material of a transformer has been attempted, but so far, most amorphous alloys produced by such methods are not yet put to industrial use. The techniques that have been used for solidification forming or compaction molding the quenched powder into an amorphous alloy of a small mass include CIP, HIP, hot press, hot extrusion, electro-discharge plasma sintering, and the like. Such techniques, however, suffered from the problems of poor flow properties due to the minute configuration, and the problem of temperature-dependent properties, namely, incapability of increasing the temperature above the glass transition temperature. In addition, forming process involves many steps, and the solidification formed materials produced suffer from insufficient properties as a bulk material. Especially, high strength, high toughness and other properties required for the face of a golf club can not be obtained. Therefore, such methods are still insufficient.
Recently, the inventors of the present invention found that a number of ternary amorphous alloys such as Ln—Al—TM, Mg—Ln—TM, Zr—Al—TM, Hf—Al—TM and Ti—Zr—TM (wherein Ln is a lanthanide metal, and TM is a transition metal of the Groups VI to VIII) ternary systems have low critical cooling rates for glass formation of the order of 10
2
K/s, and can be produced in a bulk shape with thickness up to about 9 mm by using a mold casting or a high-pressure die casting method.
It has been, however, impossible to produce a large-sized amorphous alloy material of desired configuration irrespective of the production process. There is a strong need for the development of a new solidification technique capable of producing a large-sized amorphous alloy material and an amorphous alloy having a still lower critical cooling rate for enabling the production of the amorphous alloy of larger size.
In view of such situation, the inventors of the present invention proceeded with the investigation of the bulk amorphous alloy using the ternary alloy by focusing on the effect of increasing the number of the alloy constituents each having different specific atom size as exemplified by the high glass formation ability of the ternary alloy primarily attributable to the optimal specific size distribution of the constituent atoms that are mutually different in size by more than 10%. As a consequence, the inventors found amorphous alloys of Zr—Al—Co—Ni—Cu alloy systems, Zr—Ti—Al—Ni—Cu alloy systems, Zr—Ti—Nb—Al—Ni—Cu alloy systems, and Zr—Ti—Hf—Al—Co—Ni—Cu alloy systems that have significantly lower critical cooling rates in the range of from 1 to 100 K/s, and disclosed in U.S. Pat. No. 5,740,854 (Unites States Patent corresponding to JP-A 6-249254) that alloys of. Zr—Al—Ni—Cu alloy systems may be produced into a bulk amorphous alloy material with a size of up to 16 mm in diameter and 150 mm in length by quenching the melt in a quartz tube in water.
The inventors of the present invention also disclosed in U.S. Pat. No. 5,740,854 and JP-A 6-249254 that the resulting bulk amorphous alloy material has a tensile strength of as high as 1500 MPa comparable to the compressive strength and break (crack) accompanying serrated plastic flow in the tensile stress-strain curves, and that such high tensile strength and serrated plastic flow phenomenon result in excellent malleability despite the large thickness of the bulk amorphous alloy produced by casting.
On the bases of the above-described findings of the bulk amorphous alloy production, the inventors of the present invention have continued an intensive study to thereby develop a method that is capable of producing a glassy metal material of even larger size with various configurations by a simple procedure. As a consequence, the inventors proposed a process for producing metallic glass by suction casting wherein an amorphous alloy of large size having excellent properties can be readily produced in simple operation by instantaneously casting the molten metal material in a mold cooled with water.
Such process of metallic glass production by suction casting as disclosed in U.S. Pat. No. 5,740,854 and JP-A 6-249254 is capable of producing a columnar bulk amorphous alloy, and the thus produced columnar bulk amorphous alloy exhibits good properties. In this prior art process, however, the bottom of the water cooled crucible is moved downward at a high speed and the molten metal is instantaneously cast into a vertically extending water-cooled mold to thereby attain a high moving speed of the molten metal and a high quenching rate.
In such production process, the molten metal is fluidized with the surface of the molten metal becoming wavy, and the surface area of the molten metal is increased with the increased surface area contacting the outer atmosphere. In some extreme cases, the molten metal is fluidized into small separate bulk molten metal droplets before being cast into the vertically extending mold. Therefore, the surfaces of the molten metal often meet with each other upon casting of the molten metal into the vertically extending water-cooled mold, and the so called cold shuts or discontinuities are formed at the interfaces of the thus met interfaces. The resulting bulk amorphous alloy thus suffered from inferior properties at such cold shuts, and hence, the bulk amorphous alloy as a whole suffered from poor properties.
In addition, the metal material is melted in a water-cooled hearth, and the part of the metal in contact with the hearth is at a temperature below the melting point of the metal material even if the metal material is in molten state. The part in contact with the hearth, therefore, is likely to induce nonuniform nucleation. In the above-described suction casting, such part of the molten metal which may induce uniform nucleation is also cast into the vertically extending water-cooled mold and there is a fair risk of crystal nucleus formation in the corresponding part.
Furthermore, since the bottom of the water-cooled crucible is moved downward at a high speed, the process suffered from a fair chance of the molten metal entering into the gaps formed between moveable parts and the like to reduce the reproducibility. In some extreme cases, the entering molten material is even caught in such gap
Inoue Akihisa
Makabe Eiichi
Onuki Masahide
Blount Steven
Bryant David P.
Inoue Akihisa
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