Abrasive tool making process – material – or composition – With inorganic material
Reexamination Certificate
1999-04-13
2001-03-13
Marcheschi, Michael (Department: 1755)
Abrasive tool making process, material, or composition
With inorganic material
C051S293000, C051S295000, C451S548000, C451S540000, C428S143000
Reexamination Certificate
active
06200360
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an abrasive tool for grinding, dressing, shaping or the like and also relates to a method of producing the same.
2. Description of the Related Art
Grinding wheels, a kind of abrasive tool, including polycrystalline diamond grains or cubic boron nitride grains (CBN) (i.e., superabrasive grains) have been proposed, e.g., in U.S. Pat. No. 4,923,490. Conventionally, an electrodeposited superabrasive grinding wheel includes diamond grains or CBN grains electroplated thereon. The electroplating enables the grinding wheel to copy a mold profile in detail with high precision because the manufacturing process proceeds at a relatively low temperature compared with sintering. Therefore, an electroplated grinding wheel makes possible high precision grinding, especially for high hardness and complex workpieces, so as that the demand for such grinding wheels is rising.
However, the grinding wheel tends to have a high concentration of the superabrasive grains because the grains are densely fixed on the outer peripheral surface of the grinding wheel. The high concentration of the superabrasive grains works against the engagement between the grinding wheel and the workpiece so as to increase the grinding force.
Diamond dressers, another kind of abrasive tool, have been proposed, e.g., in Japanese Published Patent Applications (Tokukoushou) 62-47669 and 53-11112. Japanese Published Patent Application 62-47669 discloses a diamond dresser whose concentration of the diamond grains is regulated by glass beads and metal balls manually prearranged on a mold using an adhesive. The percentage of the area filled with the beads and the balls determines the concentration of the diamond grains. However, it is difficult to coordinate the size of the beads or the balls.
Japanese Published Patent Application 53-11112 discloses a diamond dresser having a plurality of spiral grooves on its surface to reduce the dressing force. However, the dressing force changes whenever the grooves pass through the surface of the workpiece, so that vibrations may occur.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved abrasive tool having a preferable abrasive concentration to reduce abrasive machining force (e.g., grinding force and dressing force) and a method of producing the same.
Briefly, this and other objects of this invention as hereinafter will become more readily apparent as having been attained broadly by an abrasive tool including an electroformed layer having superabrasive grains electroplated on an outer surface of the electroformed layer, and a plurality of dimples arranged on the outer surface of the electroformed layer.
The concentration of the abrasive grains in the grinding tool is easily regulated by changing the number of the dimples (i.e., changing a dimple-area-rate). Therefore, the abrasive tool has a preferable concentration so as to effectively engage a workpiece to provide excellent abrasive machining efficiency, because the dimples catch chips broken off from the workpiece during abrasive machining. Thus the abrasive machining force (e.g., grinding force and dressing force) is reduced.
Since the dimples also retain coolant to cool the superabrasive grains, wear of the superabrasive grains is reduced, so that life of the abrasive tool is extended.
Moreover, the abrasive tool maintains high-precision abrasive machining for a long time because the outer surface of the abrasive tool is uniformly dotted with the dimples.
For producing an abrasive tool, a gel adhesive is arranged on an electrically conductive mold to form a plurality of projections. Next, the superabrasive grains are arranged on the mold and are temporarily fixed on the mold by electroplating. After removing non-electroplated superabrasive grains from the mold, an electroformed layer is made to fix the superabrasive grains on the mold by re-electroplating. Finally, the mold is removed with the projections, to form dimples.
Since the projections for the dimples are made of a gel adhesive, they are easily produced and the dimples are simply formed by removing the mold with the projections.
Therefore, the abrasive tool is produced simply and inexpensively. By changing the shape, number, density, location or size of the projections, desired dimples are easily produced. The shape of the nozzle discharging the gel adhesive determines the projection profile corresponding to the shape of the dimples. The size of the dimple depends on the amount of discharged gel adhesive. As described above, the dimple-area-rate is also changed easily to produce desired abrasive tool with a preferable concentration.
In the case that the gel adhesive is an electrically insulating material, few superabrasive grains locate in the dimples because the superabrasive grains on the projections are not electroplated. This minimizes the usage of the superabrasive grains to reduce the cost of the abrasive tool.
The gel adhesive preferably has a viscosity of 500,000 cP or smaller, and the dimple-area-rate is preferably from 7 to 70% in the abrasive tool.
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patent: 60-39071 (1985-02-01), None
patent: 61-181666 (1986-11-01), None
patent: 62-7361 (1987-01-01), None
patent: 62-47669 (1987-10-01), None
patent: 4-223871 (1992-08-01), None
Asano Hiroaki
Imai Tomoyasu
Kitajima Masato
Kodama Hayashi
Yanagisawa Masashi
Marcheschi Michael
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Toyoda Koki Kabushiki Kaisha
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