Abrasive Articles with Novel Structures and Methods for Grinding

Abstract

Bonded abrasive tools, having novel porous structures that are permeable to fluid flow, comprise a relatively low volume percentage of abrasive grain and bond, and a relatively low hardness grade, but are characterized by excellent mechanical strength and grinding performance. Methods for making the abrasive tools utilizing agglomerated abrasive grain are described.

1 . A bonded abrasive tool, comprising a three-dimensional composite of 
 (a) a first phase comprising 24-48 vol % abrasive grains bonded with 10-38 vol % organic bond material and less than 10 vol % porosity; and    (b) a second phase consisting of 38-54 vol % porosity;    wherein the second phase is a continuous phase within the composite, and the bonded abrasive tool has a minimum burst speed of 4000 sfpm (20.32 m/s).    
     
     
         2 . The bonded abrasive tool of  claim 1 , wherein the first phase of the composite comprises 26-40 vol % abrasive grains bonded with 10-22 vol % organic bond material and less than 10 vol % porosity, and the second phase consists of 38-50 vol % porosity.  
     
     
         3 . The bonded abrasive tool of  claim 1 , wherein the first phase of the composite comprises 24-42 vol % abrasive grains bonded with 18-38 vol % organic bond material, and the second phase consists of 38-54 vol % porosity.  
     
     
         4 . The bonded abrasive tool of  claim 1 , wherein 10 to 100 vol % of the abrasive grains in the first phase of the composite are in the form of a plurality of grains agglomerated together with an organic binder material.  
     
     
         5 . The bonded abrasive tool of  claim 1 , wherein 10 to 100 vol % of the abrasive grains in the first phase of the composite are in the form of a plurality of grains agglomerated together with an inorganic binder material.  
     
     
         6 - 7 . (canceled)  
     
     
         8 . The bonded abrasive tool of  claim 5 , wherein the bonded abrasive tool has a maximum elastic modulus value of 10 GPa and a minimum burst speed of 6000 sfpm (30.48 m/s).  
     
     
         9 . (canceled)  
     
     
         10 . The bonded abrasive tool of  claim 5 , wherein the inorganic binder material is selected from the group consisting of vitrified bond materials, ceramic bond materials, glass-ceramic bond materials, inorganic salt materials and metallic bond materials, and combinations thereof.  
     
     
         11 . The bonded abrasive tool of  claim 1 , wherein 10 to 100 vol % of the abrasive grains in the first phase of the composite are in the form of a mixture of a plurality of grains agglomerated together with an inorganic binder material and a plurality of grains agglomerated together with an organic binder material.  
     
     
         12 . The bonded abrasive tool of  claim 1 , wherein the first phase of the composite is a reticulated network of abrasive grain anchored within the organic bond material.  
     
     
         13 . (canceled)  
     
     
         14 . The bonded abrasive tool of  claim 1 , wherein at least 50 vol % of the abrasive grains in the first phase of the composite are in the form of a plurality of grains agglomerated together with an organic binder material.  
     
     
         15 . A bonded abrasive tool comprising a three-dimensional composite of 
 (a) 22-46 vol % abrasive grains bonded with 4-20 vol % inorganic bond material; and    (b) 40-68 vol % interconnected porosity;    wherein a majority of the abrasive grains are present as irregularly space clusters within the three-dimensional composite; the bonded abrasive tool has an elastic modulus value that is at least 10% lower than the elastic modulus value of an otherwise identical conventional tool having regularly spaced abrasive grains within a three-dimensional composite; and the bonded abrasive tool has a minimum burst speed of 4000 sfpm (20.32 m/s).    
     
     
         16 - 17 . (canceled)  
     
     
         18 . The bonded abrasive tool of  claim 15 , wherein the interconnected porosity has been formed without adding porosity inducing materials during manufacturing and the composite is substantially free of high aspect ratio particles of abrasive grains and fillers.  
     
     
         19 . The bonded abrasive tool of  claim 15 , wherein 10 to 100 vol % of the abrasive grains in the composite are in the form of a plurality of grains agglomerated together with an inorganic binder material.  
     
     
         20 - 22 . (canceled)  
     
     
         23 . The bonded abrasive tool of  claim 15 , wherein the bonded abrasive tool has an elastic modulus value that is at least 25% lower than the elastic modulus value of an otherwise identical conventional tool having regularly spaced abrasive grains within a three-dimensional composite and the bonded abrasive tool has a minimum burst speed of 6000 sfpm (30.48 m/s).  
     
     
         24 . (canceled)  
     
     
         25 . The bonded abrasive tool of  claim 15 , wherein the bonded abrasive tool is an inner diameter grinding wheel and the wheel contains 40 to 52 vol % abrasive grain and has an elastic modulus value of 25 to 50 GPa.  
     
     
         26 . The bonded abrasive tool of  claim 15 , wherein the bonded abrasive tool is a toolroom grinding wheel and the wheel contains 39 to 52 vol % abrasive grain and has an elastic modulus value of 15 to 36 GPa.  
     
     
         27 . The bonded abrasive tool of  claim 15 , wherein the bonded abrasive tool is a creep feed grinding wheel and the wheel contains 30 to 40 vol % abrasive grain and has an elastic modulus value of 8 to 25 GPa.  
     
     
         28 . A method for disc grinding, comprising the steps of: 
 (a) providing a bonded abrasive wheel, comprising a three-dimensional composite of    (i) a first phase comprising 24-48 vol % abrasive grains bonded with 10-38 vol % organic bond material and less than 10 vol % porosity; and    (ii) a second phase consisting of 38-54 vol % porosity;    wherein the second phase is a continuous phase within the composite, and the bonded abrasive tool has a minimum burst speed of 4000 sfpm (20.32 m/s);    (b) mounting the bonded abrasive wheel on a surface grinding machine;    (c) rotating the wheel; and    (d) bringing a grinding surface of the wheel into contact with a workpiece for a sufficient period of time to grind the workpiece;    whereby the wheel removes workpiece material at an effective material removal rate, the grinding surface of the wheel remains substantially free of grinding debris and, after grinding has been completed, the workpiece is substantially free of thermal damage.    
     
     
         29 - 30 . (canceled)  
     
     
         31 . The method for disc grinding of  claim 28 , wherein the bonded abrasive wheel is a flat disc, having at least one circular face and a radial perimeter and the grinding surface of the wheel is the circular face of the disc.  
     
     
         32 . A method for creep feed grinding, comprising the steps of: 
 (a) providing a bonded abrasive wheel comprising a three-dimensional composite of    (i) 22-46 vol % abrasive grains bonded with 4-20 vol % inorganic bond material; and    (ii) 40-68 vol % interconnected porosity;    wherein a majority of the abrasive grains are present as irregularly space clusters within the three-dimensional composite; the bonded abrasive tool has an elastic modulus value that is at least 10% lower than the elastic modulus value of an otherwise identical conventional tool having regularly spaced abrasive grains within a three-dimensional composite; and the bonded abrasive tool has a minimum burst speed of 4000 sfpm (20.32 m/s);    (b) mounting the bonded abrasive wheel on a creep feed grinding machine;    (c) rotating the wheel; and    (d) bringing a grinding surface of the wheel into contact with a workpiece for a sufficient period of time to grind the work piece;    whereby the wheel removes workpiece material at an effective material removal rate and, after grinding, the workpiece is substantially free of thermal damage.    
     
     
         33 - 34 . (canceled)  
     
     
         35 . The method of  claim 32  for creep feed grinding, wherein the bonded abrasive wheel has two circular faces and a radial perimeter and the grinding surface of the wheel is the radial perimeter.