US3518068A - Process for manufacturing grinding wheels containing coppercoated grains - Google Patents

Process for manufacturing grinding wheels containing coppercoated grains Download PDF

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Publication number
US3518068A
US3518068A US687807A US3518068DA US3518068A US 3518068 A US3518068 A US 3518068A US 687807 A US687807 A US 687807A US 3518068D A US3518068D A US 3518068DA US 3518068 A US3518068 A US 3518068A
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Prior art keywords
diamond
pressure
grinding
resin
abrasive
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Expired - Lifetime
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US687807A
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English (en)
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Kenneth H Gillis
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General Electric Co
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General Electric Co
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/14—Anti-slip materials; Abrasives
    • C09K3/1436—Composite particles, e.g. coated particles
    • C09K3/1445—Composite particles, e.g. coated particles the coating consisting exclusively of metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D18/00—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
    • B24D18/0009—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for using moulds or presses

Definitions

  • This invention relates to an abrasive tool in which the abrasive is diamond particles, and to a process of preparing such an abrasive tool.
  • a molding pressure is applied which may vary from 250 to as high as 10,000 pounds per square inch but which is most frequently several thousand p.s.i., and the mold is heated to an elevated temperature suflicient to make the resin granules deform plastically at the pressure used.
  • Normal practice is to use a stop in the mold which maintains the volume at nearly that level established by the cold volume of the resin at the initial pressure. As molding proceeds, relaxation of the mixture ordinarily occurs, so that the pressure initially applied to the mixture will gradually decrease during the compaction when the stop is reached, irrespective of the force applied to the mold.
  • the pressure is deliberately maintained at a given level at the beginning of the compacting operation and then at a second and lower level during the remainder of the compacting operation.
  • the pressure is adjusted in the inverse direction but is accompanied by a decrease in temperature.
  • the resin-bonded abrasive tool contains diamond abrasive which has been coated with a metal and molded at a pressure which is deliberately maintained at a substantially constant level throughout the compacting cycle until densification of the tool is completed.
  • the maintenance of constant pressure means that the volume must be continuously readjusted during the molding cycle to maintain the pressure at a given constant level.
  • the invention contemplates the use of a constant pressure during the molding cycle which is as high or higher than the highest pressures conventionally used in the preparation of diamond grinding wheels. In practical terms, this will translate into a preferred constant pressure during the molding cycle of 10,000 p.s.i. or greater. By constant pressure, it is of course understood that this refers to the pressure level after full pressure is achieved.
  • this invention involves the utilization of constant pressures during densification or compaction of a diamond grinding wheel in which the diamond has been coated with from 30-80% by weight of copper metal.
  • a grinding wheel core 1 for example of aluminum, is placed in the steel die 2 having a central portion 3.
  • a mixture 4 of diamond particles, resin granules and filler powder is then placed in a mold cavity 5, the mixture being distributed around the mold cavity as uniformly as possible.
  • a press ring 6 is placed in mold opening 5, and the entire unit is then placed in a hydraulic press between heated platens (not shown). The volume of mixture is sufficient so that, even at full densification, the upper edge of press ring 6 does not penetrate beyond the vertical portion of cavity 5.
  • the temperature is raised to :a level depending upon the particular resin used, sufficient to allow plastic deformation and plastic flow of the resin granules and to effect the thermal curing of the resin into a cohesive mass. Normally this temperature will range from about 200 C.
  • the platens of the press are brought together with a force sufficient so that the pressure on the projected normal area of the wheel rim (of resin, diamond and filler) is at the desired level.
  • the force on the platens is maintained so that the platens follow the compacting mixture and a constant pressure is maintained on the resin-diamond-filler mixture until curing of the resin is completed and full densification of the wheel rim has occurred.
  • the temperature is maintained at (or above) its initial value during the entire cycle.
  • the duration of the compaction cycle and therefore the time during which the pressure and temperature are maintained at a constant level will vary considerably, but normally will be from a few minutes to one hour. It should of course be understood that maintenance of the pressure at a constant level throughout the molding cycle refers to the pressure level after maximum pressure is achieved. There is a relatively brief time during which pressure buildup must occur.
  • the abrasive is coated with a metal prior to the molding operation.
  • Diamond has been coated with a metal for a variety of purposes for many years.
  • the coating of diamond particles with a metal such as nickel. increases the performance, as measured by grinding ratio, of the diamond abrasive, particularly when used in a resin-bonded wheel used in wet grinding operations, i.e., operations which utilize a liquid coolant, commonly water, during the grinding operation.
  • a liquid coolant commonly water
  • the present invention achieves its greatest performance improvement when used in such dry grinding operations in which the dry grinding wheel contains diamond coated with from 30-80% by weight of a metal, preferably copper, and the wheel is molded in accordance with the constant pressure cycle above described.
  • the operating temperatures are normally higher than wet grinding.
  • the resin bond of the grinding wheel or other abrasive tool accordingly thermally degrades and the efiiciency of performance in dry grinding operations is much lower than in wet grinding.
  • the amount of filler 1s necessarily adjusted downward to compensate for the addition of metal via the metal coating to give the molding mixture sufficient plasticity to mold at the relatively low pressures used.
  • Filler is needed primarily to strengthen the resin bond at elevated temperatures. For dry grinding wheels, a reduction of filler content cannot be made because of the demanding hot-strength requirement. This has, therefore, acted as a limitation on the use of metal coatings on the abrasive in dry grinding applications.
  • Heat damage to the resin is the chief mechanism of wheel wear when used for dry grinding.
  • the heat conductivity of a filled resin system is improved significantly when full density is achieved.
  • the last few percent density improvement has been found most important and accounts, at least in part, for the dramatic improvement achieved by the present process.
  • the metal coating should itself comprise from about 80% by weight of the total weight of the coated diamond abrasive.
  • the thickness of the metal coating will normally range from about 1-50 microns, although this thickness will vary with the mesh size of the abrasive, the specific matrix selected and the ultimate application intended.
  • the abrasive will normally be between about and 325 US. standard sieve size.
  • the percentage of metal coating will vary from the lower end of the 3080% range for the larger size abrasive to the upper end of the range for the smaller size abrasive.
  • a preferred range of coating weight is from -60% by weight for so-called 100 concentration diamond grinding wheels.
  • a 100 concentration wheel contains 25% by volume diamond and is about the maximum common concentration.
  • the diamond used in the grinding wheel of the invention may be either natural or synthetically produced, although the latter is preferred as it normally produces superior performance in grinding wheels.
  • the coating metal may be any of a variety of metallic materials, including but not limited to copper, nickel, gold, silver, aluminum, cobalt, titanium, tantalum, molybdenum, vanadium, chromium, niobium and alloys of these metals.
  • the metallic coating is copper. This results from the fact that the invention has its greatest advantages in the case of dry grinding applications. Dry grinding applications normally involve greater thermal stresses and require more 4 elficient heat conductivity in the grinding wheel. Copper possesses a number of unique properties, making it particularly suitable for use in the present invention, including its very high thermal conductivity, its wide and relatively cheap availability and its ease of plating on the abrasive.
  • the filler acts to improve the thermal conductivity of the resin, stiffen the resin matrix, and improve the abrasive resistance of the resin. It may or may not perform all of these functions in a given wheel.
  • a preferred filler material for use in this invention is silicon carbide because of its high thermal conductivity.
  • other filler materials which may be used include boron carbide, aluminum oxide, silicon dioxide and metallic powder, as for example copper.
  • the resinous bonding material most commonly used in resin-bonded grinding wheels is a phenol-formaldehyde reaction product, a typical example of which is a Bakelite resin sold by the Union Carbide Corporation under the designation BRP 5727.
  • other resinous or organic polymeric bonding materials may be used, as for example rubber, shellac, melamine or urea-formaldehyde resins, epoxy resins, polyesters, polyamide and polyimide resins.
  • the grinding wheels of the invention will contain by volume 25% diamond abrasive and about 25- 40% each of filler and resin. If the abrasive is coated, the filler and resin contents will be proportionately adjusted downward to the lower end of the ranges.
  • the copper-coated diamond was then mixed with silicon carbide as filler and a granulated phenol-formaldehyde (BRP 5727) resin.
  • the proportions of the three ingredients were as follows:
  • the grinding ratio of (1) wheels made in accordance with the above example was compared with (2) wheels prepared from copper-coated diamond pressed and compacted in the same manner, except that a pressure of 10,000 p.s.i. was applied to the wheel during the first six or seven minutes of the molding cycle, and a pressure of 2,000 p.s.i. was applied during the last 38 or 39 minutes of the molding cycle. This pressure cycle was selected because it is typical of standard practice.
  • the foregoing wheels were also compared with (3) wheels containing uncoated diamond pressed at 10,000 p.s.i. and then 2,000 p.s.i. (variable pressure), as in sample 2. The wheels were otherwise identical in every respect.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Composite Materials (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
US687807A 1967-12-04 1967-12-04 Process for manufacturing grinding wheels containing coppercoated grains Expired - Lifetime US3518068A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US68780767A 1967-12-04 1967-12-04

Publications (1)

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US3518068A true US3518068A (en) 1970-06-30

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US687807A Expired - Lifetime US3518068A (en) 1967-12-04 1967-12-04 Process for manufacturing grinding wheels containing coppercoated grains

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US (1) US3518068A (enrdf_load_stackoverflow)
JP (1) JPS4820517B1 (enrdf_load_stackoverflow)
BE (1) BE724829A (enrdf_load_stackoverflow)
CH (1) CH500050A (enrdf_load_stackoverflow)
DE (1) DE1809787A1 (enrdf_load_stackoverflow)
FR (1) FR1594022A (enrdf_load_stackoverflow)
GB (1) GB1236779A (enrdf_load_stackoverflow)
NL (1) NL6817421A (enrdf_load_stackoverflow)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3645706A (en) * 1969-12-16 1972-02-29 Gen Electric Resinoid grinding wheels containing nickel-coated cubic boron nitride particles
US3650715A (en) * 1969-04-04 1972-03-21 Du Pont Abrasive compositions
US3850590A (en) * 1970-09-28 1974-11-26 Impregnated Diamond Prod Ltd An abrasive tool comprising a continuous porous matrix of sintered metal infiltrated by a continuous synthetic resin
US3864101A (en) * 1972-04-19 1975-02-04 Sherwin Williams Co Process for preparing a resin-bonded grinding article containing stress-absorbing particulate material
US3868232A (en) * 1971-07-19 1975-02-25 Norton Co Resin-bonded abrasive tools with molybdenum metal filler and molybdenum disulfide lubricant
US3871840A (en) * 1972-01-24 1975-03-18 Christensen Diamond Prod Co Abrasive particles encapsulated with a metal envelope of allotriomorphic dentrites
US3923476A (en) * 1973-01-22 1975-12-02 Alexander Rose Roy Method of producing coated abrasive particles
US3984214A (en) * 1973-03-05 1976-10-05 Federal-Mogul Corporation Metal-coated diamond abrasive article containing metal fillers
US4110939A (en) * 1977-06-13 1978-09-05 The Carborundum Company Cuprous oxide containing resin bonded abrasive article and process for manufacturing same
US4369046A (en) * 1979-06-15 1983-01-18 Abrasives International N.V. Process for making an abrasive grinding wheel
USRE31883E (en) * 1969-12-16 1985-05-14 General Electric Company Resinoid grinding wheels containing nickel-coated cubic boron nitride particles
US4618349A (en) * 1982-05-10 1986-10-21 Tokyo Shibaura Denki Kabushiki Kaisha Grinding wheel manufacturing method
CN107186634A (zh) * 2017-06-22 2017-09-22 芜湖浙鑫新能源有限公司 低气孔率树脂基磨具及其制备方法
CN111022535A (zh) * 2019-12-27 2020-04-17 中国科学院兰州化学物理研究所 一种风电偏航制动器用改性聚酰亚胺摩擦材料及其制备方法
CN112621580A (zh) * 2020-12-17 2021-04-09 广东纳德新材料有限公司 一种复合金刚石磨块及其制备方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE758964A (fr) * 1969-11-14 1971-05-13 Norton Co Elements abrasifs

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2193265A (en) * 1937-09-01 1940-03-12 Carborundum Co Manufacture of abrasive articles
US2367404A (en) * 1943-07-09 1945-01-16 Fish Schurman Corp Abrasive composition of matter and method of forming same
FR1142688A (fr) * 1956-02-15 1957-09-20 Outil abrasif perfectionné et son procédé de fabrication
US3383191A (en) * 1965-06-03 1968-05-14 Simonds Abrasive Company Diamond abrasive article containing hexagonal crystalline boron nitride particles

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2193265A (en) * 1937-09-01 1940-03-12 Carborundum Co Manufacture of abrasive articles
US2367404A (en) * 1943-07-09 1945-01-16 Fish Schurman Corp Abrasive composition of matter and method of forming same
FR1142688A (fr) * 1956-02-15 1957-09-20 Outil abrasif perfectionné et son procédé de fabrication
US3383191A (en) * 1965-06-03 1968-05-14 Simonds Abrasive Company Diamond abrasive article containing hexagonal crystalline boron nitride particles

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3650715A (en) * 1969-04-04 1972-03-21 Du Pont Abrasive compositions
USRE31883E (en) * 1969-12-16 1985-05-14 General Electric Company Resinoid grinding wheels containing nickel-coated cubic boron nitride particles
US3645706A (en) * 1969-12-16 1972-02-29 Gen Electric Resinoid grinding wheels containing nickel-coated cubic boron nitride particles
US3850590A (en) * 1970-09-28 1974-11-26 Impregnated Diamond Prod Ltd An abrasive tool comprising a continuous porous matrix of sintered metal infiltrated by a continuous synthetic resin
US3868232A (en) * 1971-07-19 1975-02-25 Norton Co Resin-bonded abrasive tools with molybdenum metal filler and molybdenum disulfide lubricant
US3871840A (en) * 1972-01-24 1975-03-18 Christensen Diamond Prod Co Abrasive particles encapsulated with a metal envelope of allotriomorphic dentrites
US3864101A (en) * 1972-04-19 1975-02-04 Sherwin Williams Co Process for preparing a resin-bonded grinding article containing stress-absorbing particulate material
US3923476A (en) * 1973-01-22 1975-12-02 Alexander Rose Roy Method of producing coated abrasive particles
US3984214A (en) * 1973-03-05 1976-10-05 Federal-Mogul Corporation Metal-coated diamond abrasive article containing metal fillers
US4110939A (en) * 1977-06-13 1978-09-05 The Carborundum Company Cuprous oxide containing resin bonded abrasive article and process for manufacturing same
US4369046A (en) * 1979-06-15 1983-01-18 Abrasives International N.V. Process for making an abrasive grinding wheel
US4618349A (en) * 1982-05-10 1986-10-21 Tokyo Shibaura Denki Kabushiki Kaisha Grinding wheel manufacturing method
CN107186634A (zh) * 2017-06-22 2017-09-22 芜湖浙鑫新能源有限公司 低气孔率树脂基磨具及其制备方法
CN111022535A (zh) * 2019-12-27 2020-04-17 中国科学院兰州化学物理研究所 一种风电偏航制动器用改性聚酰亚胺摩擦材料及其制备方法
CN111022535B (zh) * 2019-12-27 2021-03-26 中国科学院兰州化学物理研究所 一种风电偏航制动器用改性聚酰亚胺摩擦材料及其制备方法
CN112621580A (zh) * 2020-12-17 2021-04-09 广东纳德新材料有限公司 一种复合金刚石磨块及其制备方法
CN112621580B (zh) * 2020-12-17 2022-08-26 广东纳德新材料有限公司 一种复合金刚石磨块及其制备方法

Also Published As

Publication number Publication date
FR1594022A (enrdf_load_stackoverflow) 1970-06-01
NL6817421A (enrdf_load_stackoverflow) 1969-06-06
BE724829A (enrdf_load_stackoverflow) 1969-05-16
JPS4820517B1 (enrdf_load_stackoverflow) 1973-06-21
CH500050A (de) 1970-12-15
DE1809787A1 (de) 1969-07-17
GB1236779A (en) 1971-06-23

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