Flexible polishing wheel and method for producing same

• US 4,128,972 A
• Filed: 04/14/1975
• Issued: 12/12/1978
• Est. Priority Date: 04/14/1975
• Status: Expired due to Term

• Current Assignee: Ramron-Bancroft Incorporated
• Original Assignee: The Osborn Manufacturing Corporation
• Inventors: Charvat, Vernon K.
• Primary Examiner(s): Arnold, Donald J.
• Application Number:
  US05/567,775
• Time in Patent Office: 1,338 Days
• Field of Search: 51/295, 51/296, 51/298, 51/299
• US Class Current: 51/298
• CPC Class Codes: B24D 18/0009 using moulds or presses
• CPC Class Codes: B24D 3/22 Rubbers synthetic or natural
• CPC Class Codes: B24D 3/28 Resins or natural or synthetic macromolecular compounds B24D3/22 takes precedence
• CPC Class Codes: B24D 3/32 for porous or cellular structure

Abstract

Differentiation between grinding wheels which are dimensionally stable in use and which remove stock to specification tolerances and polishing wheels which are flexible and which primarily do not remove stock but which "fill the valleys with the hills" call for different development. This invention is directed to a polishing tool (wheel) comprising selected abrasive, filler and plastic elastomeric bond to produce a non-rigid solid tool (wheel) of minimum voids content, the cured elastomeric bond alone characterized by a Shore hardness of 45-55 but the completed tool face hardness is not in excess of about 96 "Shore A" hardness. The so limited polishing wheel is characterized by non-chattering, non-loading, aggressive and is yet non-smearing. It is arrived at by accurate volume control ratios of the components essentially present in the product.

Claims

1. An abrasive polishing wheel having a "Shore A" hardness of less than 96 and comprising,

(a) an abrasive grain in an amount of from about 55 to about 90% of the theoretical weight of grain required to fill the volume occupied by the wheel,

(b) from about 40% to about 55% by volume of an elastomer bond, said elastomer having an unfilled cured "Shore A" hardness of from about 50 to about 60 and a density of greater than 1 gram/cm³,

(c) from zero up to about less than 15% by volume of an inert filler having an average particle diameter of less than 10 microns, and

(d) less than 10% by volume of voids.

2. The wheel of claim 1 wherein the "Shore A" hardness of the wheel is within the range of from about 85 to about 95.

3. The product of claim 1, where the elastomer bond is a non-foamed polyurethane resin.

4. The product of claim 1, where the elastomer bond is a non-foamed polyepoxide resin.

5. The product of claim 1, where the total voids in said wheel are less than about 5%.

6. A method for cavity molding a polishing wheel characterized by its freedom from loading, chattering and smearing which comprises:

(1) determining the apparent volume of dry particulate abrasive grains essential to fill the wheel mold cavity under densest packing arrangement, (2) reducing the apparent volume of said abrasive grains by a factor of at least 0.1 but not more than 0.45, (3) mixing the reduced volume of abrasive grains with (4a) a mixture of organic liquids which react to form an essentially foam-free solid polymer, said solid polymer characterized by a (Shore A) hardness of more than 50 but not more than about 60 in a volume not more than about 55% and not less than 40% of said wheel mold cavity volume and (4b) a volume of particulate filler, said volume being less than the difference between said mold volume and the sum of the true volume of the adjusted abrasive plus the volume of the solid convertible liquids, but sufficient to reduce the total voids volume in the cured wheel to less than 15% of the mold volume, (5) filling the molds with the plastic mixture and (6) allowing the plastic mixture to convert to a solid polymeric form in the mold before removal.

7. The method of claim 6 where the organic liquids are selected to form foam-free polyurethane solid polymers.

8. The method of claim 6, where the organic liquids are selected to form foam-free polyepoxide solid polymers.

9. The process of claim 6, where the volume of particulate filler is sufficient to reduce the final voids volume content of the cured wheel to less than about 5%.