Abrading – Machine – Endless band tool
Reexamination Certificate
1999-08-20
2001-08-14
Banks, Derris H. (Department: 3723)
Abrading
Machine
Endless band tool
C451S526000, C451S527000, C451S548000, C451S529000
Reexamination Certificate
active
06273805
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flexible grindstone that can be used to grind a curved surface of a workpiece such as stone speedily, as well as to a method of manufacturing such a grindstone.
2. Description of the Related Art
As a flexible coarse grinding tool having a large grain size (such as #
40
, #
60
, or #
150
) that is required to provide a large grinding force and to grind a large amount of material, there has been known a sheet-shaped flexible vitrified grinding tool having a plurality of grinding projections that include grinding grains. However, such a conventional grinding tool is poor in terms of making contact with a curved surface of a workpiece (such as stone), and involves difficulty in forming a smooth curved surface.
FIGS. 13 and 14
show a flexible vitrified diamond grinding tool invented by the inventors of the present invention (Japanese Utility Model Publication (kokoku) No. 4-5252). In
FIG. 13
, numeral
1
denotes cylindrical grinding chips, which are formed by disposing vitrified mixed powder containing grinding grains of diamond or cubic crystal boron nitride (CBN) in a die having a plurality of small holes arranged in line along concentric circles and then burning the powder.
Numeral
2
denotes a flexible base such as imitation leather impregnated with thermosetting resin. The grindstone portion is formed by the grinding chips
1
and the base
2
.
To attach the grinding chips
1
to the base
2
in an integrated manner, the base
2
is impregnated with the thermosetting resin and then the grinding chips
1
are placed on the top thereof. Subsequently, the grinding chips
1
and the base
2
are heated, so that the thermosetting resin hardens while the grinding chips
1
and the base
2
combine into an integrated unit.
After the grinder portion is formed, a surface fastener
3
is attached to the back surface of the base
2
which has been hardened with flexibility. When grinding is performed, the surface fastener
3
is attached to a fastener of the attachment fixed to the output shaft of an electrically-driven or air-driven tool.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a grindstone for grinding a workpiece such as stone, which is more flexible at contact points with the workpiece than are conventional vitrified grinding tools, and which can evade collision of the segments with the workpiece and can grind a curved surface of the workpiece through smooth contact therewith.
According to a first aspect of the present invention, there is provided a sheet-shaped grindstone for grinding a workpiece, the grindstone characterized by comprising a plurality of segments arranged in an appropriate pattern with sufficient spaces therebetween such that the grindstone becomes flexible. The segments are formed as follows: metal powder including diamond grinding grains is sintered to form pellet chips; the chips are disposed in a die; and gaps around the pellet chips are filled with a resin through application of pressure.
According to a second aspect of the present invention, there is provided a sheet-shaped grindstone for grinding a workpiece, characterized by comprising a plurality of segments arranged in an appropriate pattern with sufficient spaces therebetween such that the grindstone becomes flexible. The segments are formed as follows: metal powder including diamond grinding grains is sintered to form granular chips; the chips are disposed in a die in such a density that the chips come into mutual contact; and gaps around the granular chips are filled with a resin through application of pressure.
According to a third aspect of the present invention, there is provided a method for manufacturing a grindstone for grinding a workpiece, characterized in that metal powder including diamond grinding grains is sintered to form granular chips; the chips are disposed in a die in such a density that the chips come into mutual contact; and gaps around the granular chips are filled with a resin through application of pressure, so that the grindstone is formed in a desired shape.
According to a fourth aspect of the present invention, there is provided a sheet-shaped grindstone for grinding a workpiece, characterized by comprising a plurality of segments arranged in an appropriate pattern with sufficient spaces therebetween such that the grindstone becomes flexible. The segments are formed as follows: vitrified bond containing diamond grinding grains is burned to form granular chips; the chips are disposed in a die in such a density that the chips come into mutual contact; and gaps around the granular chips are filled with a resin through application of pressure.
According to a fifth aspect of the present invention, there is provided a method for manufacturing the grindstone for grinding a workpiece, characterized in that vitrified bond containing diamond grinding grains is burned to form granular chips; the chips are disposed in a die in such a density that the chips come into mutual contact; gaps around the granular chips are filled with a resin through application of pressure, so that the grindstone is formed in a desired shape.
Preferably, each of the above-described grindstones has a surface fastener bonded onto the back surface of the grindstone.
Preferably, each of the above-described methods comprises a step of bonding a surface fastener onto the back surface of the grindstone.
In the sheet-shaped grindstone according to the present invention, a plurality of segments are arranged in an appropriate pattern with sufficient spaces therebetween so that the grindstone becomes flexible, and each of the segments is formed such a way that metal powder including diamond grinding grains is sintered to form pellet chips, the chips are disposed in a die, and gaps around the pellet chips are filled with a resin through application of pressure. Therefore, it becomes possible to easily manufacture a superior metal bond grindstone of a complicated shape, which has the elasticity of resin and the cutting ability of the pellet chips.
In the grindstone of the present invention, each segment is manufactured in such a way that metal powder (or vitrified bond) containing diamond grinding grains is sintered (or burned) to form granular chips, the chips are disposed in a die, and gaps around the granular chips are filled with a resin through application of pressure. The grindstone can be made more flexible compared to the grindstone in which metal pellet chips are buried in a resinoid base, and grinding of a workpiece having a curved surface becomes easier. Moreover, the periphery of the grindstone also can be used for grinding.
REFERENCES:
patent: 4618349 (1986-10-01), Hashimoto et al.
patent: 5782682 (1998-07-01), Han et al.
patent: 045252 (1992-02-01), None
Banks Derris H.
McDonald Shantese
Showa Kenma Kogyo Co., Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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