Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
  • B24D11/001—Manufacture of flexible abrasive materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
  • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D2203/00—Tool surfaces formed with a pattern

Definitions

• Abrasive belts having precisely shaped abrasive composites formed from small abrasive particles dispersed in a cured resin binder and molded into shaped structures can be aligned at an angle other than zero or ninety degrees with respect to the edge of the belt as disclosed in US patent 5,489,235 to Gagliardi. See Figure 1.
• the abrasive composites on the abrasive belt create a scratch pattern that crosses the previous scratch pattern (non- scribing pattern). The crossing patterns lead to a more random, less uniform scratch pattern which provides finer surface finishes.
• Shaped abrasive particles as disclosed for example in US patent 8,142,531, provide significantly improved cut over the shaped abrasive composites disclosed in Gagliardi.
• a new problem was discovered. Namely, the shaped abrasive particles, when aligned at an angle other than zero or ninety degrees to the longitudinal axis of the belt, created a significant side force or side load that must be counteracted in order for the belt to track properly. No such side force or side loads were created by the belt disclosed in Gagliardi when using the abrasive composites.
• the belt may have a tendency to track off to the side of the grinding machine; especially, as the load on the work piece is significantly increased. This can be especially problematic in situations when a high work piece load is applied for a short duration, the work piece removed from the belt, and then reapplied for another short duration high load cycle.
• the belt tracking system of the grinding machine sees repeated cycles with high belt side load and then no belt side load. Adjusting the belt to track properly with no side load present can cause the belt to not track properly when the side load is present and vice versa.
• This problem is most acute for abrasive belts that are short, narrow, or under low tension and contain larger sized shaped abrasive particles.
• the inventors determined that one way to solve this problem was to limit the angular rotation of the shaped abrasive particles on the belt thereby limiting the generated side loads during grinding while still providing a non-scribing, finer finish on the work piece.
• the invention resides in an abrasive belt comprising: a backing and an abrasive layer adhered to the backing by a make coat resin and the abrasive layer comprising a plurality of shaped abrasive particles; a first belt side and a second belt side opposing the first belt side with the first and second belt sides generally aligned with a longitudinal axis of the grinding belt; at least 30% of the shaped abrasive particles in the abrasive layer having a first face and placed onto the backing such that an angle between the first face and the longitudinal axis is greater than 0 degrees and less than or equal to 20 degrees.
• shaped abrasive particle means a ceramic abrasive particle with at least a portion of the abrasive particle having a predetermined shape.
• Shaped abrasive particles exclude abrasive composites formed from abrasive particles dispersed in a cured resin binder and molded into shaped structures as used for example in US patent 5,489,235.
• Ceramic shaped abrasive particles are generally homogenous or substantially uniform and maintain their sintered shape without the use of a binder such an organic or inorganic binder that bond smaller abrasive particles into an agglomerated structure and excludes abrasive particles obtained by a crushing or comminution process that produces abrasive particles of random size and shape.
• the ceramic shaped abrasive particles comprise a homogeneous structure of sintered alpha alumina or consist essentially of sintered alpha alumina.
• the ceramic shaped abrasive particle is made from a boehmite sol gel that is molded, dried, calcined and sintered to form a ceramic alpha alumina shaped abrasive particle.
• the shape is replicated from a mold cavity used to form the precursor shaped abrasive particle.
• the shaped abrasive particle will generally have a predetermined geometric shape that substantially replicates the mold cavity that was used to form the shaped abrasive particle.
• the mold cavity could reside on the surface of an embossing roll or be contained within a flexible belt or production tooling.
• the shaped abrasive particles can be precisely cut from a sheet of dried sol-gel by a laser beam into the desired geometric shape.
• Suitable shaped abrasive particles are disclosed in the following non- limiting patents and publications: US2014290147 (Everts et al); US2014007518 (Breder et al); US2013337262 (Barnes et al); US8840696 (Czerepinski et al); US8753742 (Arcona et al); US8758461 (Czerepinski et al); US2013263525 (Erickson); US8728185 (Adefris); US2013040537 (Adefris et al); US2012227333 (Adefris et al); US8764865 (Adefris et al); US2010319269 (Erickson); US8034137 (Adefris et al); US8142532 (Adefris et
• FIG. 1 is a perspective view of an abrasive belt.
• FIG. 2 is a perspective view of a shaped abrasive particle.
• FIG. 3 is a graph of Side Force vs Cycle for various abrasive belts.
• FIG. 4 is a graph of Cut vs Cycle for various abrasive belts.
• a coated abrasive article in the form of an abrasive belt 10 comprises a backing 12 having a first layer of binder, hereinafter referred to as the make coat resin 14, applied over a first major surface 15 of the backing 12. Attached or partially embedded in the make coat 14 are a plurality of shaped abrasive particles 16 forming an abrasive layer 18.
• the abrasive layer 18 comprises a patterned abrasive layer with at least some of the shaped abrasive particles spaced and positioned onto the backing in a pre-determined pattern.
• the shaped abrasive particles can be spaced from each other a pre-determined amount in the X and Y directions and have a specified angular rotation about the Z-axis that is parallel to a shaped abrasive particle longitudinal axis 20 of an individual shaped abrasive particle.
• the abrasive belt has a first belt side 22, a second belt side, 24, and a belt longitudinal axis 26.
• the belt can be left as shown in FIG. 1 for use in a cartridge grinder where the belt is unwound, directed over the work piece, and then rewound.
• the ends 28 of the belt can be spliced and joined together to form an endless abrasive belt in the form of a loop using readily known methods.
• a second layer of binder hereinafter referred to as the size coat resin 30 can be applied.
• the size coat has been minimized in FIG. 1 to better illustrate the orientation of the shaped abrasive particles.
• the purpose of make coat resin 14 is to secure shaped abrasive particles 16 to backing 12 and the purpose of size coat 30 is to reinforce shaped abrasive particles 16 in the abrasive layer 18 to better secure them within the abrasive layer and to the backing.
• the shaped abrasive particle 16 has a first face 32 and an opposing second face 34 separated by a thickness t. The first face and the second face are joined to each other by a sidewall 36.
• the sidewall is a sloping sidewall having a specific draft angle, a, between the second face and the sidewall as disclosed in US patent 8,142,531.
• the shaped abrasive particle has a length, 1, measured along the shaped abrasive particle longitudinal axis 20.
• a perimeter of both the first face and the second face is triangular, and in some embodiments the perimeter is an equilateral triangle.
• Other shaped abrasive particles can be used as listed in the definition above.
• At least 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 percent of the shaped abrasive particles 16 in the abrasive layer 18 are placed onto the backing such than an offset angle, ⁇ , between the first face 32 and the belt longitudinal axis 26 is greater than 0 degrees and less than or equal to 20 degrees.
• At least 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 percent of the shaped abrasive particles 16 in the abrasive layer 18 are placed onto the backing such than an offset angle, ⁇ , between the first face 32 and the belt longitudinal axis 26 is greater than 0 degrees and less than or equal to 10 degrees.
• At least 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 percent of the shaped abrasive particles 16 in the abrasive layer 18 are placed onto the backing such than an offset angle, ⁇ , between the first face 32 and the belt longitudinal axis 26 is greater than 0 degrees and less than or equal to 5 degrees.
• ⁇ an offset angle between the first face 32 and the belt longitudinal axis 26 is greater than 0 degrees and less than or equal to 5 degrees.
• a specified range for the angle, ⁇ has been shown to limit the side load or side force generated by the abrasive layer with the rotated shaped abrasive particles.
• the term "length” refers to the maximum dimension of a shaped abrasive particle and is typically along the shaped abrasive particle longitudinal axis 20.
• “Width” refers to the maximum dimension of the shaped abrasive particle that is perpendicular to the length and is typically perpendicular to the shaped abrasive particle longitudinal axis 20.
• the terms “thickness” or “height” refer to the dimension of the shaped abrasive particle that is perpendicular to the length and width. See Fig. 2 where length and thickness are shown for the triangular shaped abrasive particle.
• Shaped ceramic abrasive particles are typically selected to have a length in a range of from 1 micron to 15000 microns, more typically 10 microns to about 10000 microns, and still more typically from 150 to 2600 microns, although other lengths may also be used.
• Shaped ceramic abrasive particles are typically selected to have a width in a range of from 0.1 micron to 3500 microns, more typically 100 microns to 3000 microns, and more typically 100 microns to 2600 microns, although other lengths may also be used.
• Shaped ceramic abrasive particles are typically selected to have a thickness in a range of from 0.1 micron to 1600 microns, more typically from 1 micron to 1200 microns, although other thicknesses may be used.
• shaped ceramic abrasive particles may have an aspect ratio (length to thickness) of at least 2, 3, 4, 5, 6, or more.
• the make coat resin 14 and size coat resin 30 comprise a resinous adhesive.
• the resinous adhesive of the make coat resin can be the same as or different from that of the size coat resin.
• resinous adhesives that are suitable for these coats include phenolic resins, epoxy resins, urea-formaldehyde resins, acrylate resins, aminoplast resins, melamine resins, acrylated epoxy resins, urethane resins and combinations thereof.
• the make coat resin or size coat resin, or both coats may further comprise additives that are known in the art, such as, for example, fillers, grinding aids, wetting agents, surfactants, dyes, pigments, coupling agents, adhesion promoters, and combinations thereof.
• fillers include calcium carbonate, silica, talc, clay, calcium metasilicate, dolomite, aluminum sulfate and combinations thereof.
• a supersize coating may be applied over the size coat as well as disclosed in the Examples.
• a grinding aid can be applied to the coated abrasive article.
• a grinding aid is defined as particulate material, the addition of which has a significant effect on the chemical and physical processes of abrading, thereby resulting in improved performance. Grinding aids encompass a wide variety of different materials and can be inorganic or organic.
• the backing 12 can be any suitable material used for abrasive articles such as, paper, film, cloth, nonwovens, vulcanized fiber, plastics, and the like.
• a combination of shaped abrasive particles and other abrasive grains such as crushed abrasive particles or diluent particles can be used as disclosed for example in US. Patent publication US 2012/0231711 and in US patent number 5,496,386.
• two or more shaped abrasive particles may be placed into close proximity by forming multiplexed shaped abrasive structures of duplexed, triplexed or even more shaped abrasive particles as disclosed in PCT Application No. PCT/US2015/045505 filed on August 17, 2015 entitled Coated Abrasive Articles with Multiplexed Structures of Abrasive Particles and Method of Making.
• a production tool having a plurality of cavities dimensioned to hold a single shaped abrasive particle or multiple shaped abrasive particles are provided for precise positioning, rotational orientation, and transfer of the shaped abrasive particles to a coated backing thereby forming a patterned abrasive layer where the X-Y spacing and rotational orientation about the Z axis of at least 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 percent of each shaped abrasive particle in the abrasive layer can be predetermined and controlled for a specific grinding application.
• the production tooling and the coated backing having a make coat resin applied are brought into close proximity and the shaped abrasive particles are transferred from the cavities in the tooling and onto the backing to form a pre-determined pattern or patterned abrasive layer with the shaped abrasive particles.
• the make coat resin is then cured, typically a size coat resin is applied and cured, and the coated abrasive article is converted into a belt.
• Shaped abrasive particles were prepared according to the disclosure of U.S. Patent
• the shaped abrasive particles were prepared by molding alumina sol gel in equilateral triangle-shaped polypropylene mold cavities of side length 0.068 inch (1.73 mm) and a mold depth of 0.012 inch (0.3 mm). After drying and firing, the resulting equilateral, triangular shaped abrasive particles resembled FIG. 1 A except the draft angle a of a sloping sidewall was approximately 98 degrees. The fired shaped abrasive particles were about 1.3 mm (side length) x 0.27 mm thick and would pass through a 20- mesh sieve.
• the abrasive belt of Comparative Example A was obtained as 3MTM CUBITRONTM II ABRASIVE CLOTH BELT 984F, 36+ YF-WEIGHT from 3M, Saint Paul, Minnesota.
• the triangular shaped abrasive particles are applied to the backing by an electrostatic deposition process and therefore the first face of each shaped abrasive particle is randomly orientated with respect to the belt's longitudinal axis.
• Untreated polyester cloth having a weight of 300-400 grams per square meter
• a 10.16 cm x 114.3 cm strip of this backing was taped to a 15.2 cm x 121.9 cm x 1.9 cm thick laminated particle board.
• the cloth backing was coated with 229 g/m 2 of a phenolic make resin consisting of 52 parts of resole phenolic resin (obtained as GP 8339 R- 23155B from Georgia Pacific Chemicals, Atlanta, GA), 45 parts of calcium metasilicate (obtained as WOLLASTOCOAT from NYCO Company, WiUsboro, NY), and 2.5 parts of water using a putty knife to fill the backing weave and remove excess resin.
• a phenolic make resin consisting of 52 parts of resole phenolic resin (obtained as GP 8339 R- 23155B from Georgia Pacific Chemicals, Atlanta, GA), 45 parts of calcium metasilicate (obtained as WOLLASTOCOAT from NYCO Company, WiUsboro, NY), and 2.5 parts of water using a putty knife to fill the backing weave and remove excess resin.
• the shaped abrasive particles prepared according to the disclosure of U.S. Pat. No. 8,142,531 (Adefris et al.) had nominal equal side lengths of 1.30 mm and a thickness of 0.27 mm, and a sidewall angle of 98 degrees.
• Sufficient bias cut tool sections to achieve a total length of 44 inches (111cm) were lined up end to end and mounted to a second 15.2 cm x 121.9 cm x 1.9 cm thick particle board.
• a 1.0 cm diameter hole was drilled through the thickness at the midpoint of the 15.2 cm dimension and approximately 2.54 cm from each end of both of the laminated particle boards.
• a base was constructed that had a 0.95 -cm diameter vertical dowels at each end to engage the holes in the particle boards and thereby align the placement of first the abrasive particle filled tooling (open side up), followed by the make resin-coated backing (coated side down).
• Several spring clamps were attached to the particle boards to hold the construction together.
• the clamped assembly was removed from the dowels, flipped over (backing now coated side up and tooling open side down) and placed back onto the base using the dowels to maintain alignment.
• the back of the laminated particle board was repeatedly tapped lightly with a hammer to transfer the abrasive particles to the make-coated backing.
• Abrasive grains having a basis weight of 727 g/m 2 were thus applied.
• the tape was removed and the abrasive coated backing and it was placed in an oven at 90°C for 1.5 hours to partially cure the make resin.
• a size resin consisting of 43.15 parts of resole phenolic resin (obtained as GP 8339 R-23155B from Georgia Pacific Chemicals, Atlanta, GA), 9.7 parts of water, 22.75 parts of cryolite (Solvay Chemicals, Inc, Houston, Texas), 22.75 parts calcium metasilicate (obtained as WOLLASTOCOAT from NYCO Company, Willsboro, NY) and 1.65 parts red iron oxide was applied to each strip at a basis weight of 503 g/m 2 , and the coated strip was placed in an oven at 90°C for 1 hour, followed by and 8 hours at l02°C .
• the side force in pounds increased as the offset angle, ⁇ , between the belt longitudinal axis and the first face increased.
• the side force was approximately the same as the electrostatically coated belt Comparative A and nominally zero.
• an offset angle, ⁇ of less than or equal to 5 degrees had the same side force load as an electrostatically coated belt but because the shaped abrasive particles are slightly rotated a non-scribing finish is obtained.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Polishing Bodies And Polishing Tools (AREA)

Priority Applications (8)

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Family Applications (1)

Country Status (9)

Cited By (40)

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Citations (5)

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• 2015
  • 2015-11-24 US US15/528,843 patent/US20170312887A1/en not_active Abandoned
  • 2015-11-24 JP JP2017529685A patent/JP2017536254A/ja not_active Withdrawn
  • 2015-11-24 CA CA2969698A patent/CA2969698A1/en not_active Abandoned
  • 2015-11-24 KR KR1020177017666A patent/KR20170093167A/ko unknown
  • 2015-11-24 CN CN201580065355.1A patent/CN107000172A/zh active Pending
  • 2015-11-24 BR BR112017011549A patent/BR112017011549A2/pt not_active Application Discontinuation
  • 2015-11-24 WO PCT/US2015/062411 patent/WO2016089675A1/en active Application Filing
  • 2015-11-24 EP EP15866335.1A patent/EP3227054A4/de not_active Withdrawn
  • 2015-11-24 RU RU2017117880A patent/RU2017117880A/ru not_active Application Discontinuation

Patent Citations (5)

Non-Patent Citations (1)

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