Abrading – Abrading process – With tool treating or forming
Reexamination Certificate
1999-02-05
2001-05-01
Ostrager, Allen (Department: 3725)
Abrading
Abrading process
With tool treating or forming
C451S072000, C451S443000, C051S307000, C051S309000
Reexamination Certificate
active
06224469
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a tool for both of cutting and grinding which can be applied to both efficient rough cutting and mirror surface grinding for both ductile materials and hard and brittle materials.
BACKGROUND ART
In manufacturing a metal mold as a base technique in a manufacturing industry, high speed and high quality machining using a machining tool having a high reliability is particularly desired. In metal mold machining, rough cutting is a first process to shape a workpiece into a desired form. The total volume of material which is cut off by rough cutting is very large. Therefore, an extremely high machining efficiency is required in rough cutting. In addition, a machining precision such as surface roughness or surface shape is required in the final product. In order to reduce the whole process time, not only the process time required for rough machining and finish machining is reduced but also a reduction of a set-up time which is needed as part of those processes is important.
As a rough cutting tool for manufacturing the metal mold, a cutting tool such as ball end mill or milling cutter has been widely used. Although the cutting tool can perform efficient rough machining, the shape of the end of the tool is changed due to wear and it is difficult to compensate for this change, so that there is a problem that the machining precision such as surface roughness or surface shape is low.
As a finishing tool for manufacturing the metal mold, a grinding tool using a grinding wheel has been widely used. As for the grinding tool, however, it is difficult to efficiently and stably grind a ductile material such as aluminum, copper, or plastic due to clogging of the grinding surface.
Further, in the case of rough cutting by a rough cutting tool and finishing by a finishing tool, a detachment and a re-attachment of the tool or workpiece is indispensable, so that there is a problem that an occurrence of attachment error cannot be avoided.
In association with a development of the recent technology, desire for ultraprecise machining has rapidly and highly advanced. As electrolytic grinding means which satisfies the above desire, the electrolytic in-process dressing (ELID) grinding method has been developed and proposed by the same applicant as the present invention (“Trend of Latest Technique of Mirror-grinding” in RIKEN Symposium held on the fifth of March, 1992).
The ELID grinding method is a method in which a conductive grinding wheel is used in place of an electrode in the conventional electrolytic grinding, an electrode which faces the grinding wheel at a distance is provided, a voltage is applied between the grinding wheel and the electrode while a conductive liquid is supplied between the grinding wheel and the electrode, and the workpiece is ground by the grinding wheel while dressing the grinding wheel with electrolysis. In the ELID grinding method, even when abrasive grain are fine, no clogging of the grinding wheel occurs by dressing the abrasive grains with electrolytic dressing. Consequently, by using abrasive fine grains, a very excellent surface like a mirror surface can be obtained with ELID grinding. Therefore, it is expected that the ELID grinding method, when applied to various grinding jobs can maintain the cutting ability of the grinding wheel from highly efficient grinding to mirror surface grinding and can form a highly accurate shape in a short time, which cannot be realized by the prior art.
In the ELID grinding method, although it is possible to grind at a high efficiency without clogging of the grinding wheel, it is difficult to eliminate chips with respect to relatively soft, ductile material such as aluminum, copper, or plastic, because such materials cannot be deeply cut. Therefore, there is a problem that the machining efficiency is lower than that as a conventional cutting tool such as a ball end mill or milling cutter.
DISCLOSURE OF THE INVENTION
The present invention is invented in order to solve the above-mentioned various problems. That is, it is a main object of the present invention to provide a tool for both cutting and grinding which can be applied to both efficient rough cutting and mirror surface grinding for a ductile material and a hard and brittle material without detaching and re-attaching a tool or a workpiece. Another object of the present invention is to provide a tool for both cutting and grinding which can compensate for tool wear.
According to the invention, there is provided a tool for both cutting and grinding comprising: a plurality of diamond columns regularly arranged so as to protrude on a working surface; and a conductive bond member for integrally fixing the diamond columns, wherein the conductive bond member can be electrolytically dressed while a conductive liquid is supplied between the conductive bond member and an electrode which faces the bond member at a distance.
According to the construction of the invention, the conductive bond member which integrally fixes the diamond columns can be electrolytically dressed while the conductive liquid is supplied between the bond member and electrode which faces the bond member at a distance. Therefore, when a chip of each diamond column is worn, a protruding amount of the diamond column from the conductive bond member is reduced, and work resistance increases, the surface of the conductive bond member is eliminated by the electrolytic dressing, so that the protruding amount of each diamond column can be increased. Therefore, the protruding amount can be always optimized, the chip of the diamond column functions as a cutting blade, and the efficient rough cutting and mirror surface grinding for the relatively soft ductile material such as aluminum, copper, or plastic and the hard and brittle material such as monocrystal silicon, glass, or carbide alloy can be machined without detaching and re-attaching the tool or workpiece. Since the shape of the tool chip is hardly changed even when the tool is worn due to the machining, the excellent surface like a mirror surface can be realized and the tool wear can be easily compensated as a decreasing amount of the tool diameter.
According to a preferred embodiment of the invention, the conductive bond member is in a disc shape or a cylindrical shape and chips of the plurality of diamond columns are located on either one or both of the bottom surface and the peripheral surface of the disc or cylinder. By the construction, it can be used. as disk shaped or cylindrical shaped cutting tool and grinding wheel.
It is preferable that the diamond column comprise of monocrystal abrasive grains comprising a monocrystal having a relatively small size and polycrystal abrasive grains having a relatively large size. By this construction, the rough cutting can be executed by the polycrystal abrasive grains comprising large polycrystal at a high efficiency and the high precise grinding can be executed by the monocrystal abrasive grains comprising small monocrystal.
It be preferable that the conductive bond member is a conductive grinding wheel containing abrasive grains. By this construction, the efficient grinding of the workpiece can be executed by coming into contact with the conductive bond member.
Other objects and advantageous features of the present invention will become apparent from the following description with reference to the accompanying drawings.
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Moriyasu Sei
Nakagawa Takeo
Ohmori Hitoshi
Griffin & Szipl, P.C.
Hong William
Ostrager Allen
The Institute of Physical and Chemical Research
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