Abrading – Abrading process – With critical temperature modification or control of work or...
Reexamination Certificate
1998-10-15
2001-03-13
Eley, Timothy V. (Department: 3723)
Abrading
Abrading process
With critical temperature modification or control of work or...
C451S449000, C451S488000
Reexamination Certificate
active
06200198
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of cutting metal and non-metal materials with a tool attached to a working machine (e.g., a milling machine, lathe, grinding machine, gear cutting machine, etc.) that generates a non-combustible gas atmosphere at and around the tip of a cutting tool.
2. Description of the Related Art
Conventional cutting tools are usually attached to the spindle of a working machine and are cooled by injection of cutting liquid (e.g., liquid coolant) from the nozzle of a working machine to the top of the tool. This reduces friction and lowers the temperature of the tool, thereby ensuring more effective cutting and longer tool life. In addition, the injection pressure of the liquid coolant also works to wash away cut chips from the cutting area.
However, this conventional cutting and cooling method also necessitates the disposal of the sludge produced as a by-product of the liquid coolant. Since the used liquid coolant is mixed in with the sludge, it is difficult to dispose of the waste liquid without polluting the environment.
Environmental concerns in the workplace and in the local and global community lend impetus to the drive for better, safer preservation efforts. Thus, waste disposal of the spent cutting liquid (e.g., liquid coolant) becomes complicated and almost impossible. Under these circumstances, devising a cutting method that does not use a liquid coolant with its resulting waste is greatly needed.
Another problem exists in conventional methods because the cutting liquid is customarily recycled and reused. As a result, the liquid may experience a rise in temperature over time, possibly causing thermal expansion in machine parts. Thermal expansion is a major cause of inaccurate machining.
To overcome the above problems, there is a “dry cut” method which blows low-temperature air on the cutting part without using liquid coolant. Although sludge disposal is no longer required with the “dry-cut” or air-blow method, oxidization is accelerated at the cutting point, which results in a poor quality of the machined surface. In addition, this air-blow method provides inferior cooling efficiency of the cutting part compared to the liquid coolant method, and the cutting part becomes worn more quickly. Consequently, as the cutting part wears, the accuracy of a machined surface becomes increasingly poor.
Furthermore, when cutting is carried out on any high-viscosity material such as aluminum, a built-up edge may form on the cutting part resulting in poor accuracy on the aluminum material along with a deterioration in tool efficiency. In addition, coil-shape aluminum chips are formed making the dry-cut method more difficult.
SUMMARY OF THE INVENTION
In view of the foregoing it is, therefore, an object of the present invention to provide a method of cutting in a non-combustible gas atmosphere in which a flow of gas (e.g., nitrogen or carbon dioxide) is applied to the cutting point of a tool.
Additionally, it is an object of the present invention to provide a method of cutting in which longer tool life is secured, even under the “dry-cut” operation.
It is another object of the present invention to provide a method of cutting in which practical conditions of machining, as well as pressure, density and method of blowing of non-combustible gas, secure longer tool life.
It is a further object of the present invention to provide a method of cutting in which improved machining accuracy using iron, steel, and aluminum materials is obtained along with improved disposal of cut chips.
To achieve the above and other objects, there is provided a method of cutting metal and non-metal materials in a non-combustible gas atmosphere with a tool attached to a working machine. This is accomplished by providing a non-combustible gas atmosphere such as a nitrogen gas or a carbon dioxide gas which occupies a proportion of at least 90% at and around a cutting part which is used for machining metal and non-metal materials.
Further, there is provided a method of cutting metal and non-metal materials in a non-combustible gas atmosphere with a tool attached to a working machine, by making a non-oxide gas atmosphere of a nitrogen gas which occupies a proportion of at least 90% at and around a cutting part and at a machining temperature not less than 500° C.
In a preferred embodiment of the present invention, a coating such as a hard metal coating or multi-ply coating may be formed on the cutting part.
In a further preferred embodiment of the present invention, an ideal blow pressure of the non-combustible gas, between 0.2 Mpa (2 kg/cm
2
) and 1.0 Mpa (10 kg/cm
2
), is supplied.
In another preferred embodiment, the non-combustible gas may be supplied to the cutting part via a penetrating supply hole and the metal material may be iron steel (e.g., iron-based material).
In a further preferred embodiment, the metal material may be aluminum.
With this structure it is possible to supply the non-combustible gas, such as nitrogen or carbon dioxide, to the cutting part of the tool attached to the machine's spindle and to the space around the cutting part at a proportion of at least 90%. Since the non-combustible gas is distributed in an atmospheric dispersion to the cutting part and surrounding space, cut chips which may have become heated during cutting are cooled. Further, the oxidation resistance of the cutting part is increased, thereby preserving the life of the tool.
Further, nitrogen gas is supplied to the cutting part of the tool at a proportion of at least 90% and at a machining temperature not less than 500° C. Accordingly, the nitrogen gas forms a nitride on the cutting part surface, improving the tip's wear resistance and providing a longer tool life.
Additionally, the coating to which the nitrogen gas is supplied is further strengthened as the a hard metal or multiply coating forms on the cutting part. As a result, no sparking occurs and no defects such as coating peel-off or adhesion of cut chips are observed at the cutting part, even after expiration of the tool life. Therefore, a longer tool life can be obtained by the method of the present invention.
According to a preferred embodiment, the blow pressure of the non-combustible gas is controlled so that the preferred pressure level is obtained. This level varies, according to the type of metal or non-metal material to be machined, or to the type of tool to be used, within the range of 0.2-1.0 Mpa (2-10 kg/cm
2
). Accordingly, the non-combustible gas can effectively and economically be blown, thereby the metal or non-metal material can be effectively machined and tool life extended.
According to another aspect of the invention, the blowoff nozzle is used as a supply means for the non-combustible gas at the machining point of the cutting part. The gas supply to the preferred machining position can be carried out regardless of the shape of tool, thereby achieving the most effective application of the non-combustible gas.
Further, as a supplying nozzle (e.g., the center hole) penetrating through the tool is used as a non-combustible gas blow means, a concentrated gas supply at the narrow machining point of the cutting part can be provided. In particular, even in the case of a deep hole drilling machine or the like, it is possible to supply the gas to the workpiece to which an ordinary blowoff nozzle could not. Consequently, the most effective non-combustible gas distribution can be accomplished regardless of machining conditions.
In a further aspect, as the non-combustible gas is blown onto the iron steel material, it cools the machining point of the metal and aids oxidation resistance. An additional advantage is that the life of the cutting part is extended as the tip is nitrided. The longer tool life allows for accuracy in machining to be maintained for a greater period of time.
According to another aspect, as the non-combustible gas is blown onto the aluminum material, it cools the machining point of the metal and aids oxidation resistance. Furthermore, this method
Suzuki Takayuki
Suzuki Toshiyuki
Ukai Hisashi
Eley Timothy V.
Enshu Limited
McGinn & Gibb PLLC
LandOfFree
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