US3750347A

US3750347A - Segmental abrasive wheel

Info

Publication number: US3750347A
Application number: US00257502A
Authority: US
Inventors: R Homeyer
Original assignee: Carborundum Co
Current assignee: Stemcor Corp
Priority date: 1972-05-30
Filing date: 1972-05-30
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07

Abstract

A segmental abrasive wheel comprises a multiple layer of abrasive segments with overlapping joints, the segments being supported in grinding position between two circular flanges and held firmly by internal L-shaped bolts engaging the lower ends of the segments.

Description

Q Milled Mame Pee/em [1 1 [111 3,75%347 Homeyer' Aug. '7, 1973 SEGMENTAL ABRASWIE WHEEL 1,954,330 4/1934 Schurt 51/2065 1,982,628 12 1934 B 1 2 .5 [751 Inventor: 8" Homeyer, TOnaWanda, 2,279,486 4/1942 21/2825 2,219,398 10/1940 Rickard 51/2065 [73] Assignee: The Conway, Niagara Falls, N.Y. Primary ExaminerDona1d G. Kelly Filed: y 1972 Attorney-Dav1d E. Dougherty et al.

A segmental abrasive wheel comprises a multiple layer [52] 11.5. C1. 511/2065 of abrasivg Segments with overlapping joints the [51] 11l'lt. C1 B2411 7/06 ments being supported in g g p i between [58] Fleld of Search 51/2065, 207, 206.4 two circular flanges and held firmly by internal L shaped bolts engaging the lower ends of the segments. [56] References Cited UNITED STATES PATENTS 4 Claims, 4 Drawing Figures 1,697,505 1/1929 Hyde 51/2065 1,734,012 10/1929 Jeppson 51/2065 PATENIEU M15 7 7 sum .1 OF 2 FIG. I

PAIENIEDAUQ 71915 SHEET 2 BF 2 SEGMIEN'IAI. ABRASIVE WIIEIEIL BACKGROUND OF THE INVENTION Segmental abrasive wheels find many uses in industrial grinding operations, especially where massive grinding wheels or drums are required, for example, in pulp grinding. Smaller wheels, running at high speed, have also been developed. While a segmental wheel allows the use of harder and denser abrasives, a common difficulty has been that of finding adequate means for fastening and supporting the segments in the wheel. Since the wheel segments are subject to strong centrifugal and vibrational forces during use, the fastening means must be designed to hold each segment firmly in place and also support it against vibration and sudden mechanical shock. Abrasive segments, especially the harder ones, are somewhat brittle and tend to break suddenly in service. When this happens, the wheel must be stopped at once and the segment replaced, this can be time consuming if the wheel is so designed that several adjacent segments must be removed to get at the broken one. In other cases, segments may not break out of a wheel initially, but may instead loosen, either due to thermal expansion and contraction during service or because the fastening means cannot be sufficiently adjusted to compensate for abrasive wear of the segments against each other after the wheel has been in use for an extended time. The joints between segments also present shock points where the wheel contacts the workpiece and cracks may then develop in the segments which can cause uneven cutting and rapid segment failure.

These disadvantages become more serious as the diameter and speed of the wheel is increased. Since it is difficult to make large abrasive wheels of controlled density and uniform composition throughout, the trend is to construct them from segments and there is, consequently, a need for improved wheels in which larger segments may be used with positive means for holding the segments in place and for adjusting them to compensate for mechanical wear. The construction should minimize mechanical shock to the segments during grinding and should permit the fabrication of relatively thin wheels, such as those used for cut-off grinding.

SUMMARY OF THE INVENTION The invention provides a segmental abrasive wheel comprising a circular main flange with outer and inner coaxial annular rings, both rings being disposed on the same side of the main flange, and a circular backing flange with an outer coaxial annular ring opposite the outer coaxial ring of the main flange, the two rings being coaxially arranged with the outer coaxial annular rings facing each other and supporting between them a plurality of rows of abrasive segments. Each segment is a radial segment of a circular abrasive ring annulus, each row of segments forming a circular abrasive ring. The base portions of the segments are of concave shape to conform to the convex shape of the inner coaxial annular ring of the main flange, each segment having at least one hole in its base portion to engage with fastening means, preferably L-shaped bolts positioned in the inner ring. These fastening means hold the segments in place in the wheel, the main flange and the backing flange being drawn together by suitable means such as bolts to give the segments additional support.

DESCRIPTION OF THE DRAWINGS FIG. I is a partial axial view of the assembled segmental wheel.

FIG. 2 is a sectional view of the wheel, taken along line 22 of FIG. I.

FIG. 3 is an isometric view of a separate abrasive wheel segment.

FIG. 43 is a view of one of the L-shaped bolts used to hold the abrasive segment in place.

DETAILED DESCRIPTION The segmental abrasive wheel of the invention is built up from a number of radial segments 10, II of abrasive material, assembled in a double row on a circular main flange to give a wheel of the configuration shown in FIG. I. While multiple rows of abrasive segments may be employed, a double row as shown in FIG. I is the preferred embodiment. It will be observed that the joints between segments III in the first row of segments overlap the joints between segments II in the second row, and vice versa; thereby providing a grinding surface on the wheel periphery in which each joint between adjacent segments in each row of segments 10, II is protected during grinding by the surface of the overlapping segment in the other row. As best shown in FIG. 2, the segments I0, II are supported by an outer coaxial annular ring M in the outer periphery of the circular main flange I2 while the bases Ilia, Ila of each segment III, II are shaped in a concave fashion (See FIG. 3) and fit firmly against the corresponding convex surface of an inner coaxial annular ring I6 of the main flange I2. The segments are held firmly in position by means such as adjustable L-shaped bolts I8 (See FIG. t) which engage holes I9 (See FIG. 3) in the base portions of segments III, I I. The lower ends of the L-shaped bolts are threaded and pass through holes Ina in the inner coaxial annular ring 16. Threaded nuts 13a engage the corresponding threads of the bolt extending below ring l6. Tightening these nuts then draws the bolt and the base of the abrasive segment which it engages into firm contact with the annular ring I6. Due to slight variations in segment hole spacings, a separate bolt or set of bolts is provided for each segment, thus insuring a means for the proper adjustment of holding tension for the segment. One of these L-shaped bolts is shown in FIG. 4, the bolt tension being adjustable by the threaded nut Ida.

When all segments III, II are in place and adjusted in position on the circular main flange 12, they are further supported by a circular backing flange 20, this flange having a single coaxial annular ring 22 in its outer periphery. Flange bolts 24 pass through unthreaded openings 25 in the circular backing flange 2th and engage corresponding threaded openings 26 in the inner coaxial ring iii of the circular main flange I2. The flange bolts 2d are tightened to draw the circular main flange and circular backing flange together, thereby supporting the two rows of abrasive segments III, II between the flange rings lll and 22. Blotters or ring washers 27 of compressible materials such as leather, plastic or heavy paper may be inserted between flange ring M and segments MB, and between flange ring 22 and segments III to give a more elastic support for segments M, II. The wheel assembly is coaxial with and mounted on a shaft 2% and maybe attached thereto by appropriate supporting hubs, not shown in the drawings. Other mounting systems can also be used.

One of the abrasive segments is shown in greater detail in FIG. 3. These are segments of a circular ring annulus, the dimensions of the segment being selected to form upon assembly, a circular abrasive ring of the desired wheel size. The segments can be bonded abrasive materials such as metallic, resin or ceramic bonded segments and can comprise abrasive materials such as silicon carbide, boron nitride, alumina, diamond grit and the like, or they can be hot pressed and sintered, depending on the density and hardness desired in the finished segment. While the segment shown in FIG. 3 has a uniform thickness from base to outer peripheral surface, the thickness at the peripheral surface can be increased slightly over that of the base to give a wheel having a peripheral width greater than that at the wheel center. The segmental abrasive wheels of the invention can be used as snagging wheels or cut-off wheels and can be constructed in various wheel diameters and thicknesses as desired. The double row overlapping assembly of the abrasive segments greatly minimizes the shock action of the workpiece against the segment joints during grinding and distributes the abrasive wear uniformly over the peripheral surfaces of the segments. Since mechanical shock is reduced, the individual segments can run longer without cracking and the grinding effectiveness of the wheel is prolonged over an extended period of time. If any segments loosen because of mechanical wear during grinding, they can be readily adjusted by removing the circular backing flange and tightening the appropriate L-shaped bolts holding the segment.

What is claimed is:

1. A segmental abrasive wheel comprising:

a. a circular main flange comprising outer and inner coaxial annular rings, said rings being disposed on the same side of the main flange;

b. a circular backing flange comprising an outer coaxial annular ring opposite the outer coaxial ring of the circular main flange, said flanges being coaxially arranged with the outer coaxial annular rings facing each other;

e. a plurality of rows of abrasive segments supported between the outer coaxial annular rings of the circular main flange and the circular backing flange, the segments each being radial segments of a circular abrasive ring annulus, each row of segments forming a circular abrasive ring, the segments having base portions of concave shape to conform to the convex portion of the inner coaxial annular ring of the circular main flange, the segments having at least one hole in the base portions thereof to allow engagement with fastening means for holding the segments in place in the abrasive wheel;

d. fastening means for holding the segments in place in the abrasive wheel; and

e. means for drawing the circular main flange and circular backing flange together to support the rows of segments.

2. A segmental abrasive wheel according to claim 1 in which the means for drawing the circular main flange and circular backing flange together comprises adjustable flange bolts, positioned in the circular backing flange and engaging the inner coaxial ring of the circular main flange.

3. A segmental abrasive wheel according to claim 1 in which the fastening means comprises L-shaped bolts slideably adjustable in holes in the inner coaxial ring of the circular main flange, said bolts engaging the holes in the base portions of the abrasive segments.

4. A segmental abrasive wheel according to claim 1 in which the outer peripheral portions of the abrasive segments have a thickness greater than the thickness of the base portions of the segments.

Claims

1. A segmental abrasive wheel comprising: a. a circular main flange comprising outer and inner coaxial annular rings, said rings being disposed on the same side of the main flange; b. a circular backing flange comprising an outer coaxial annular ring opposite the outer coaxial ring of the circular main flange, said flanges being coaxially arranged with the outer coaxial annular rings facing each other; c. a plurality of rows of abrasive segments supported between the outer coaxial annular rings of the circular main flange and the circular backing flange, the segments each being radial segments of a circular abrasive ring annulus, each row of segments forming a circular abrasive ring, the segments having base portions of concave shape to conform to the convex portion of the inner coaxial annular ring of the circular main flange, the segments having at least one hole in the base portions thereof to allow engagement with fastening means for holding the segments in place in the abrasive wheel; d. fastening means for holding the segments in place in the abrasive wheel; and e. means for drawing the circular main flange and circular backing flange together to support the rows of segments.