Fixed-super-abrasive tool and method of manufacture thereof

• US 4,010,583 A
• Filed: 04/17/1975
• Issued: 03/08/1977
• Est. Priority Date: 05/28/1974
• Status: Expired due to Term

• Current Assignee: Engelhard Minerals & Chemicals Corporation
• Original Assignee: Engelhard Minerals & Chemicals Corporation
• Inventors: Highberg, Carle W.
• Primary Examiner(s): Smith, Al Lawrence
• Assistant Examiner(s): Ramsey, K. J.
• Application Number:
  US05/569,303
• Time in Patent Office: 691 Days
• Field of Search: 51/206.5, 51/209 R, 51/209 DL, 51/283, 51/284, 51/296, 51/309, 51/356, 51/397, 51/DIG. 34, 51/325
• US Class Current: 451/42
• CPC Class Codes: B24B 13/01 Specific tools, e.g. bowl-like; Production, dressing or fastening of these tools
• CPC Class Codes: B24D 18/00 Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
• CPC Class Codes: B24D 7/06 with inserted abrasive blocks, e.g. segmental

Abstract

This improved fixed-super-abrasive tool for grinding and polishing toric and other curvilinear lenses is produced by a novel method of manufacture and comprises a substantially-rigid, super-abrasive-free backing member and a malleable preformed super-abrasive wafer conformed and releasably secured thereto. The substantially-rigid, super-abrasive-free backing member has a curved support surface determinative of the curvature of the curvilinear working surface. The substantially-malleable preformed abrasive wafer has a predetermined thickness and one surface which, in the method of the present invention, is conformed to the curved support surface, either before or at the time of securing. The wafer comprises super-abrasive particles having a Knoop Hardness in excess of about 3000 kg/mm² in a malleability-imparting powdered metal matrix, which facilitates the conformation step. A porous surface may be created by introduction of particles which are dissolved during use of the tool, leaving pores which assist the grinding and polishing processes.

Claims

1. A method of manufacturing a super-abrasive tool for grinding and polishing purposes and having a curvilinear working surface of predetermined desired conformation comprising the steps of:

a. providing a substantially-rigid, non-abrasive backing member having a curved support surface determinative of the curvature of said curvilinear working surface;

b. disposing adjacent said support surface a substantially-malleable, multi-layered, integrally-formed abrasive wafer of predetermined thickness contour having a substantially smooth surface and an abrasive-containing surface, including a thickness in excess of about 1/32 inch, said abrasive wafer comprising

i. a layer of super-abrasive particles having uniform surfaces and a Knoop Hardness in excess of about 3000 kg/mm² and interspersed and bound in a powdered metal matrix having malleability-imparting properties and comprising a major proportion of copper and a minor proportion of tin and

ii. a layer comprising a malleable metal having substantially smooth surfaces and substantially free of said super-abrasive particles,

said wafer being formed by subjecting said layer of malleable metal and said layer of super-abrasive particles interspersed in a powdered metal binder to sintering conditions of pressure and temperature for the metals to form said multi-layered integrally-formed abrasive wafer;

c. causing the substantially smooth surface of said abrasive wafer to conform to said support surface so as to impart said predetermined desired conformation as to the exposed abrasive-containing surface of said abrasive wafer by interposing said wafer between said support surface and an opposed surface conformable to the predetermined desired conformation and thereafter bringing said support surface and said opposed surface towards one another with sufficient force to accomplish such conformation;

d. releasably securing the conformed wafer of (c) to said backing member.

2. The method of claim 1 wherein said curved support surface has a toric shape which is imparted to said working surface.

3. A method of grinding and polishing toric and other curvilinear lenses comprising the steps of:

a. forming a super-abrasive grinding tool comprising;

i. a substantially-rigid, non-abrasive backing member having a curved support surface determinative of the curvature of said toric and curvilinear lenses and having peripheral dimensions adapted to the motion of the optical grinding apparatus with which it is to be used by determining the area swept out by a lens in motion during the grinding of said lenses and shaping said backing member to match but not to exceed the area swept by said tool during grinding of said lens with the area swept by said lens,

ii. a substantially malleable, multi-layered, integrally-formed abrasive wafer of predetermined thickness conformed to the curvature of and releasably secured to said backing member of (i), said abrasive wafer comprising

1. a super-abrasive-containing layer comprising abrasive particles having a Knoop Hardness in excess of about 3000 kg/mm² and selected from the group consisting of diamonds, cubic boron nitride, and mixtures thereof interspersed and bound in a powdered metal matrix for binding said super-abrasive particles and,

2. a layer substantially free of super-abrasive particles secured to said super-abrasive-containing layer of (1);

said wafer being formed by subjecting said super-abrasive-free layer and said super-abrasive-containing layer to sintering conditions of pressure and temperature for the metals to form said multi-layered abrasive wafer, said wafer being conformed to said backing member by interposing said wafer between said support surface and an opposed surface conformable to the predetermined desired conformation and thereafter bringing said support surface and said opposed surface towards one another with sufficient force to accomplish such conformation;

b. mounting said grinding tool of (a) in an optical grinding machine and employing said tool to grind an optical lens while simultaneously pumping a fluid to cool, lubricate, and flush said lens during said grinding;

c. periodically restoring during its useful life the curvature of said super-abrasive-containing layer of (a) (ii) to the curvature of said backing member of (a) (i) until said super-abrasive-containing layer has been substantially consumed;

d. releasing said wafer having a substantially consumed super-abrasive-containing layer from said backing member and thereafter securing a replacement wafer to said backing member and

e. representing steps (b), (c), and (d).