Abrasive tool making process – material – or composition – Laminating
Reexamination Certificate
2001-02-21
2003-12-30
Marcheschi, Michael (Department: 1755)
Abrasive tool making process, material, or composition
Laminating
C051S295000, C051S307000, C051S308000, C051S309000, C051S293000
Reexamination Certificate
active
06669745
ABSTRACT:
BACKGROUND
This invention relates to abrasive articles having oriented abrasive particles in a matrix and to a method of making such abrasive articles.
There are many prior methods disclosed for incorporating and positioning certain types of abrasive particles in a sheet-like matrix. Such abrasive particles include diamond crystals and crystalline cubic boron nitride (CBN). Each of these abrasive materials is known to provide optimal abrasive performance when the abrasive particles are optimally positioned in the matrix which holds them in the abrasive product. Various attempts have been made to optimally position such abrasive particles in such abrasive products, but they have met with only limited success in the optimal orientation of abrasive particles. The following references provide some indication of what has been done in the past to provide a solution to this problem.
U.S. Pat. No. 4,680,199 (Vontell); U.S. Pat. Nos. 4,925,457 and 5,092,910 (de Kok); U.S. Pat. No. 5,525,100 (Kelly); U.S. Pat. No. 5,725,421 (Goers); U.S. Pat. No. 5,551,960 (Christianson); U.S. Pat. No. 5,049,165 (Tselesin); U.S. Pat. No. 5,380,390 (Tselesin); U.S. Pat. No. 5,620,489 (Tselesin); U.S. Pat. No. 6,110,031 (Preston); U.S. Pat. No. 5,791,330 (Tselesin); U.S. Pat. No. 5,695,533 (Kardys); U.S. Pat. No. 5,817,204 (Tselesin); U.S. Pat. No. 5,980,678 (Tselesin); N. Tselesin,
Improvements of Diamond Tools for Machining of Advanced Engineered Ceramics
in “Using Advanced Ceramics in Manufacturing Applications,” Conference Paper, Jun. 3-5, 1991, Cincinnati, Ohio, Publication of Society of Manufacturing Engineers, p. EM91-248-3; U.S. Pat. No. 5,190,568 (Tselesin); U.S. Pat. No. 5,203,880 (Tselesin); and U.S. Pat. Nos. 5,560,745 and 5,453,106 (Roberts).
SUMMARY OF THE INVENTION
The present invention resides in the discovery of a deficiency in what the art has taught in regards to making abrasive products having optimally oriented shaped abrasive particles. The present invention produces an abrasive product with optimally oriented shaped abrasive particles to provide optimal orientation and alignment of the sharp points of the abrasive particles for effective abrading irrespective of crystallographic orientation.
For the purpose of this invention “optimal orientation” refers to the preferred orientation desired by the manufacturer or user of the abrasive product. Optimal orientation may not always include completely erect abrasive particles should some other orientation be desired. The present invention provides a method in which substrates containing tapered or otherwise shaped surface perforated depressions (e.g., square pyramidal or conical) are used to capture and orient individual abrasive particles thereby increasing the probability of a sharp edge or point being deployed in contact with the surface of a workpiece. The shape of the depression is such that it inherently deploys the abrasive particle in an optimal orientation. The substrate within each shaped depression has a perforation which further facilitates the deployment of the abrasive particle contained therein which may permit reducing the pressure on the back side of the substrate. This technique allows the abrasive particles to arrange themselves with points or edges in a desired configuration, e.g., pointing up.
In one aspect the invention provides a method of making an abrasive article comprised of a sheet-like matrix having deployed therein a multiplicity of optimally oriented shaped abrasive particles, each abrasive particle having a shaped base end and an opposite shaped abrading end comprising:
providing a substrate forming apparatus including a first tool having a contact surface including a multiplicity of projections and a second tool having a mating surface, the contact and mating surfaces of said tools, when mated, being capable of deforming said substrate to provide perforated depressions in the substrate capable of receiving in each depression one base end of said abrasive particle and optimally orienting the abrasive particle therein;
providing an embossable, perforatable, sheet-like substrate;
contacting the sheet-like substrate with the contact and mating surfaces of said first and second tools to provide an embossed, perforated, sheet having back surface and an opposite top surface characterized by having a multiplicity of depressions wherein each depression is characterized by having a shape capable of receiving the shaped base end of said shaped abrasive particle and optimally orienting the abrasive particle therein and a perforation through the sheet-like substrate within said depression wherein the perforation is of a size which will not permit the passage of said abrasive particle;
distributing abrasive particles within said depressions substantially with one abrasive particle in each depression of the embossed, perforated sheet;
optimally orienting each abrasive particle in the depression containing the abrasive particle;
creating a pressure differential between the top surface and the back surface of said embossed, perforated sheet wherein a lower pressure is applied to the back surface to hold each oriented abrasive particle within its depression while removing at least a major portion of the abrasive particles not within said depressions from the top surface of said embossed, perforated sheet; and
permanently bonding said abrasive particles in said depressions after they are optimally oriented to provide an abrasive product which includes optimally oriented shaped abrasive particles with abrading ends exposed.
In a further aspect wherein the substrate is sinterable, the invention provides a method of making an abrasive article comprised of a sheet-like matrix having deployed therein a multiplicity of optimally oriented shaped abrasive particles, each abrasive particle having a shaped base end and an opposite shaped abrading end. The method comprises:
providing a substrate forming apparatus including a first tool having a contact surface including a multiplicity of projections and a second tool having a mating surface, the contact and mating surfaces of said tools, when mated, being capable of deforming said substrate to provide perforated depressions in the substrate capable of receiving in each depression one base end of the abrasive particle and optimally orienting the abrasive particle therein;
providing an embossable, perforatable, sinterable sheet-like substrate comprised of sinterable particles and organic binder in a layer borne on a metal foil;
contacting the sheet-like substrate with the contact and mating surfaces of said first and second tools to provide an embossed, perforated, sinterable sheet having back surface provided by said metal foil and an opposite top surface characterized by having a multiplicity of depressions wherein each depression is characterized by having a shape capable of receiving the shaped base end of said shaped abrasive particle and optimally orienting the abrasive particle therein and a perforation through the sheet-like substrate within said depression wherein the perforation is of a size which will not permit the passage of said abrasive particle;
distributing abrasive particles within said depressions substantially with one abrasive particle in each depression of the embossed, perforated, sinterable sheet;
optimally orienting each abrasive particle in the depression containing the abrasive particle;
creating a pressure differential between the top surface and the back surface of said embossed, perforated, sinterable sheet wherein a lower pressure is applied to the back surface to hold each oriented abrasive particle within its depression while removing at least a major portion of the abrasive particles not within said depressions from the top surface of said embossed, perforated, sinterable sheet;
temporarily bonding said abrasive particles in said depressions after they are optimally oriented;
heating the abrasive particle bearing embossed, perforated, sinterable sheet at a sintering temperature to provide on cooling an abrasive product which includes a sintered matrix
Koskenmaki David C.
Moh Kyung H.
Prichard Paul D.
Marcheschi Michael
Wright Bradford B.
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