Solid material comminution or disintegration – Processes – Subjecting material to impact by moving comminuting surface
Reexamination Certificate
2000-01-18
2003-07-29
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Processes
Subjecting material to impact by moving comminuting surface
C241S036000, C241S187000, C241S193000, C241S196000
Reexamination Certificate
active
06598813
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a cutting device that can cut an object formed of a single member, such as glass, ceramics, resin, metal, or the like, or a composite member thereof continuously using one kind of cutting tool. More particularly, the present invention relates to a cutting device that cuts an object while smashing the very surface area of the object by allowing an impacting body formed of a hard solid body to impact on the object at a high speed with a high frequency, and to a cutting method using the same.
BACKGROUND OF THE INVENTION
Generally, methods used for cutting and disassembling glass used in a cathode-ray tube (CRT) (herein after referred to as “CRT glass”) for the purpose of its recycling include a method of utilizing the thermal shock obtained by winding a heater wire around the CRT and energizing the heater wire to heat the CRT, a cutting method of using a diamond wheel cutter that is rotated at a high speed, a gas fusion cutting method (a method of melting and cutting glass using a gas), or the like.
Generally, sheet steel pieces (cold rolled steel plate sheets and strips cut to length or the like) forming bodies of automobiles and case bodies or other components of various household electric appliances are cut by a band-shaped cutter (a band saw machine) or a disc-shaped cutter (a metal slitting saw), which is provided with a high hardness saw blade, by a grinder cutting method using a grinding tool in which abrasive grains are formed in a disc shape or in a cylindrical shape, or by a gas fusion cutting method using an acetylene gas or the like.
Generally, resin-molded articles are cut by a band saw machine, a metal slitting saw, an end mill, or the like.
In this connection, no cutting device that can cut a member containing different materials such as glass of the CRT or the like, sheet steel, or resin-molded articles or members formed of different materials continuously one after another by rotating one kind of tool (a tool provided with a cutting blade) or by moving it at a high speed has been proposed.
However, in the respective conventional cutting methods described above, there have been the following problems.
(1) In cutting the CRT glass as described above, due to the differences in shape, size, manufacturing processes, or the like of the CRT, the residual stress in the glass also varies and therefore in the method of energizing and heating a heater wire in which the thermal shock is utilized, it is difficult to find out stable cutting and heating conditions or to form a certain stable cut surface.
In the cutting method using a diamond wheel cutter, when the cutting speed is increased, the wear rate of the diamond wheel cutter increases due to frictional heat and therefore the cutting speed is limited. In addition, the diamond wheel cutter is expensive and the cutting amount and the wear rate of the diamond wheel have a close relationship, resulting in high cutting cost.
Furthermore, in the fusion cutting method using a hot gas, the cutting speed is slow and this method is dangerous when combustible materials exist near an object to be cut or a section to be cut. Thus, the applicability of this method is limited.
(2) When the sheet steels are cut using a tool such as a band saw machine, a metal slitting saw, or the like, a cutting blade of the tool is pressed strongly against an object to be cut to cause a continuous shear fracture in the object to be cut, thus cutting and processing the object to be cut.
Since the cutting blade is pressed strongly against the object to be cut, frictional heat is generated greatly at the cutting part. Therefore, the embrittlement and enfeeblement of its cutting edge due to the heat aggravate the abrasion of the cutting edge.
Due to the abrasion of the cutting blade, the cutting speed is lowered considerably and thus is limited. In addition, since the cutting blade is allowed to bite into the object to be cut, a holding mechanism is required to have a high stiffness for holding the tool (a cutter) and the object to be cut, thus requiring a large-scale holding mechanism and a high installation cost.
The grinder cutting method using a grindstone is carried out by causing continuous small shears by cutting blades provided in the abrasive grains. Since the corners (cutting blades) of the abrasive grains are not so sharp and the peripheral speed of the grinder is relatively high, the frictional heat is generated greatly at the cutting part. In order to secure the life span of the grindstone, it is necessary to control the temperature of the cutting part appropriately. Thus, the cutting speed is limited.
In the gas fusion cutting method using a gas such as acetylene, it is important that no combustibles exist in the vicinity of the cutting section in view of safety. Therefore, the applicability of the gas fusion cutting method is limited.
(3) In using a band saw machine, a metal slitting saw, or the like for cutting a resin-molded article or the like, when the cutting speed is increased, the vicinity of the cutting part of an object to be cut starts burning or melts due to the frictional heat generated by the friction with the tool, thus causing a change in physical properties of the object.
(4) When a blade made of a material containing a ferroalloy as a main constituent is used in cutting a metallic magnetic component, the fragments and powder that are produced by cutting an object to be cut are magnetic substances and thus adhere to the edge of the blade. Consequently, the increase in frictional resistance or the damage of the edge lowers the cutting performance of the blade considerably.
(5) It is extremely difficult to cut an object formed of a plurality of members with different physical properties (for example, metal, resin-molded articles, glass, ferrite, or the like) continuously using the same tool.
(6) When the information required for cutting and processing (physical properties or the like) an object is unknown or when an object to be cut is formed of a plurality of members and the shapes and materials of the members hiding behind the surface member are unknown, optimal cutting conditions cannot be found out merely from the image information of the surface and outer shape of the object to be cut. Therefore, the automatic control for optimal cutting is impossible.
SUMMARY OF THE INVENTION
In order to solve the above-mentioned problems, the present invention puts a theory to practical use in a cutting device. The theory is a plastic wave theory in which when a high-speed tensile force is applied at least at a critical impact velocity, a fracture occurs immediately at the part where the force has been applied, or a theory in which when a high-speed compressive force is applied at least at a critical impact velocity, the ductility is deteriorated rapidly and thus the part where the force has been applied is broken even by a small distortion (a phenomenon similar to the embrittlement).
Particularly, a cutting device according to the present invention replaces a conventional tool provided with a blade, and in the cutting device an impacting body formed of a hard solid body such as metal is allowed to impact on an object to be cut (hereinafter referred to as “an object to be processed” or “a work”) at a very high speed with a high frequency to generate a plastic wave by the impact energy, thus breaking and removing the part subjected to the impact instantaneously.
In other words, the present invention provides a cutting device based on the following principle: when an impacting body that executes a high speed circular motion impacts on a work at least at the critical impact velocity of the work and then rebounds, the surface of the work in a highly limited area including the part subjected to the impact by the impacting body and its vicinity is smashed (broken) instantaneously into a minute granular state or minute fragments by a high speed compression that occurs together with impact, a high speed tension due to friction, high speed shearing, or the like.
Generally, in processing a w
Matsushita Electric - Industrial Co., Ltd.
Merchant & Gould P.C.
Rosenbaum Mark
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