US3290835A

US3290835A - Segmental abrasive wheel

Info

Publication number: US3290835A
Application number: US385639A
Authority: US
Inventors: Henry J Jeffers
Original assignee: Carborundum Co
Current assignee: Kennecott Corp
Priority date: 1964-07-28
Filing date: 1964-07-28
Publication date: 1966-12-13
Anticipated expiration: 1983-12-13
Also published as: GB1040680A

Description

Dec. 13, 1966 H. J. JEFFERS 3,290,835

SEGMENTAL ABRASIVE WHEEL Filed July 28, 1964 INVENTOR.

HENRY J. JEFFERS FIG. 4

A'I 'TORNEY United States Patent "ice 3,290,835 SEGMENTAL ABRASIVE WHEEL Henry J. Jeffers, Lewiston, N.Y., assignor to The Carborundum Company, Niagara Falls, N.Y., a corporation of Delaware Filed July 28, 1964, Ser. No. 385,639 9 Claims. (Cl. 51-209) The invention of the present application relates to segmental abrasive wheels and is particularly concerned with such wheels in which the segmentscomprise diamond abrasive.

It is an object of the present invention to provide abrasive wheels of the character described in which diamond abrasive segments bonded with metal or the like are embedded in an organic-bonded mass of softer abrasive gram.

Another object of the invention is to provide abrasive wheels of the character described in which mounting means for said wheels are also embedded in an organicbonded mass of relatively soft abrasive grain.

A further object of the invention is to provide abrasive Wheels of the character described in which there are a plurality of series of diamond abrasive segments.

Still another object of the invention is to provide abrasive wheels of the character described which cut more smoothly and with reduced vibration.

Other objects and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a plan view of an abrasive disc wheel embodying the present invention;

FIGURE 2 is a transverse sectional view on line 22 of the abrasive disc wheel shown in FIGURE 1;

FIGURE 3 is a transverse sectional view on line 33 of the abrasive disc wheel shown in FIGURE 1; and

FIGURE 4 is an inverted perspective view of a diamond abrasive segment such as is employed in producing abrasive wheels according to the present invention.

Referring to FIGURES 1-3, inclusive, the abrasive disc wheel referred to comprehensively by the reference numeral 11 is seen to comprise an abrasive body portion 13 of substantial thickness in one face of which there are embedded a plurality of

abrasive segments

15, 16 each of which is suitably secured to a mounting plate 18. In the other face of the body portion 13 of the wheel 11 there are embedded a plurality of wheel-

mounting nuts

20, 21.

Abrasive wheels according to the invention may be easily manufactured and readily mounted for use. The production of such a Wheel may be accomplished as follows:

EXAMPLE I A series of alternating diamond

abrasive segments

15 and 16 is placed in a ring mold (not shown). The outer abrasive faces of the segments are turned down to rest on the bottom mold plate. The latter is upwardly beveled adjacent its outer edge so that the outer abrasive faces of the segments 15 are arranged at an obtuse angle with respect to the outer abrasive faces of the segments 16. An abrasive mix, preferably one with a resinoid bond, is then placed in the mold around the

segments

15 and 16, and leveled off. An annular top mold plate, to the underside of which the wheel-mounting nuts 20 and 21 have been secured by machine screws passing through the plate and engaging in the threaded

bores

22 and 23, respectively, of the nuts, is then placed on the mix and a pressure of about 210 kg./cm. is applied to consolidate the mix, thus molding the

nuts

20 and 21 in the abrasive body portion 13 of the wheel. The mold barrel and bottom mold plate are then removed and the wheel is turned over and cured with the top mold plate still attached. Upon completion of the cure the machine screws 3,290,835 Patented Dec. 13, 1966 are removed and the wheel, with substantially fiush abrasive segments, is ready for finishing and sale or use.

Novel segmental wheels according to the invention could, if desired, be formed in other ways according to known practices. However, the procedure given in Example I is ordinarily preferred.

In carrying out the manufacture of the present novel segmental abrasive wheels the

abrasive segments

15 and 16 are preferably metal or metalloid bonded and comprise about 5-10 percent of. diamonds. Segments produced according to the following example are very effective.

EXAMPLE II A mix consisting of the following:

Percent Wolfram carbide, finely divided 85.0 Cobalt, finely divided 8.5 Diamond abrasive, 20-46 grit 6.5

is blended together and heated to about 1300 C. in a stop mold. Pressure is then applied to close the mold against the stop. After pressing, the segments are cooled and attached to the mounting plates or spiders 18.

The mounting plates 18 for the segments are preferably steel and are U-shaped, with the legs 19 of the U being shorter than the base and extending divergently, and provided with irregular contours which permit firm anchoring in the abrasive body portion 13 of the wheel. The

segments

15 and 16 are secured to the outsides of the bases of the U-shaped plates. The mounting plates 18 can be cut to shape or may be punched from perforated sheet metal. As shown, they preferably are about the same width as the abrasive segments with the legs 19 extending beyond the segments. i

It will be understood that alternatively the abrasive segments may be formed of diamond abrasive and other hard bonds such as other carbide-metal compositions, steel, and hard bronzes as well as hard ceramic bonds. Many bonds of these types are well-known. It will also be understood that the percentage of diamond abrasive used in such segments may vary as found desirable. The segments may be of any desired size.

Depending upon the material of the mounting plates 18 and the bond for the diamond

abrasive segments

15 and 16, the latter may be attached to the former by any suitable means. The use of a suitable, conventional silver solder is preferred. However, strong, resinous adhesives such as polyester or epoxy adhesives will be satisfactory in many instances and other adhesives may be used when desired.

The bond and abrasive of abrasive body portions 13 of segmental abrasive wheels according to the present invention are preferably softer than those of the

abrasive segments

15 and 16 and will, therefore, wear away at least as fast as the segments. Preferably the body portion is formed of resinoid-bonded abrasive particles, the abrasive being, for example, fused aluminum oxide or silicon carbide. Although the grit size of the abrasive used in the abrasive body portion is preferably finer than that of the diamond abrasive in the

segments

15 and 16 the proportions of bond to abrasive, the exact bond composition, and the type of abrasive are not critical and any known or desired abrasive mix may be used. As examples of usable mixes are those disclosed in US. Patents 2,076,517 and 2,254,254, issued respectively on April 6, 1937 and September 2, 1941.

The

mounting nuts

20 and 21 embedded, substantially flush, in the back of the wheels 11 may be of any desired shape and size. As mentioned above, they are provided with threaded

bores

22 and 23, respectively, into which bolts may be threaded to hold the wheel on a metal base plate for rotation. Preferably the nuts Will be formed of steel to give adequate strength to the mounting.

It will be understood that the precise arrangement of abrasive segments shown in the accompanying drawing is not critical. The segments may be closer together or further apart in either or both of the series and, if desired the number of segments in one series may be more or less than the number in the other. The number, spacing, and arrangement of the abrasive segments are matters of choice to be decided on the basis of results desired.

The same is true of the number and arrangement of mounting nuts. In using a segmental wheel of the present invention it is mounted on a grinding machine by securing it to a mounting plate with machine screws that pass through the plate and engage in the

nuts

20 and 21. Enough of such nuts should be provided to adequately secure the wheel.

Segmental abrasive wheels according to the invention are characterized by high abrasive eificiency, long life, and convenience in use. Because of their novel construction they are lighter and easier to handle than the wheels previously used which included heavy base plates to which the segments were secured by soldering, brazing, or the like. In addition they cut more smoothly with reduced noise and vibration.

Parts and percentages referred to-herein are parts and percentages by weight.

I claim:

1. A segmental diamond abrasive wheel which comprises a disc-like abrasive body portion comprising abrasive particles and an organic bond therefor, said abrasive body portion having embedded in one face thereof a plurality of annularly-spaced diamond abrasive segments, the bond of said segments being harder than the bond of said body portion, and said abrasive body portion having embedded in the opposite face thereof a plurality of annularly-space mounting nuts, said segments being firmly secured to individual mounting plates, each of said mounting plates comprising a plurality of portions extending beyond the periphery of the segment mounted thereon and being wholly embedded in said body portion whereby to permit firm anchoring of said segments in said abrasive body portion.

2. A segmental diamond abrasive wheel asset in claim 1 in which said segments are mounted on U-shaped plates that are embedded in said body portion and the outer faces of said segments are flush with the surface of said body portion.

3. A segmental diamond abrasive wheel as set forth in claim 2 in which said organic bond is a resinoid.

4. A segmental diamond abrasive wheel as set forth in claim 2 in which the bond of said segments comprises a metal.

5. A segmental diamond abrasive wheel as set forth in claim 2 in which the abrasive of said body portion is softer than diamond.

6. A segmental diamond abrasive wheel as set forth in claim 2 in which said segments are radially oriented in said body portion.

7. A segmental diamond abrasive wheel as set forth in claim 2 in which said segments are mounted in two radially spaced series. I

8. A segmental diamond abrasive wheel as set forth in claim 7 in which the longitudinal axes of the segments of the outer one of said radially spaced series are inclined with respect to the longitudinal axes of the segments of the inner series.

9. A segmental diamond abrasive wheel which comprises an annular, disc-like abrasive body comprising abrasive particles and a resinoid bond therefor, a plurality of diamond abrasive segments, the bond of said segments comprising a metal and being harder than the bond of said body portion, each of said segments being mounted on U-shaped plates which are embedded in one face of said body portion with the outer abrasive face of said segments substantially flush with the surface of said body portion, and a plurality of annularly-spaced mounting nuts embedded in the opposite face of said body portion with the outer faces of said nuts substantially flush with the surface of said body portion.

References Cited by the Examiner UNITED STATES PATENTS 3/1922 Gardner 5l209 12/1940 Benner et al. 5l-209