US2115897A - Abrasive article - Google Patents

Description

May 3, 1933- c. E. wooDDELL ET Al. 2,115,897

ABRASIVE ARTICLE Filed May 15, 1955 flimsy!! nl INVENTOR. CHARLES E. wooDDELl. CHARLES S. NELSON ROY LINCOLN Patented May, 1938 -l PATiazNTl OFFICE 2,115,897 ABitAslvE ARTICLE Charles E. Wooddell and Charles S. Nelson, Ni-

agara Falls, and Roy Lincoln, Buil'alo, N. Y., assignors, by mesne assignments, to The Carborundul'n Company, Niagara Falls, N. Y., a corporation oi' Delaware Application May 15, 1935, serial No. 23,144

1 Claim.

This invention relates to improved abrasive articles. More speciiically the invention is concerned with abrasive belts or bands adapted for rotation about pulleys or for mounting on wheels provided with a yieldable and resilient peripheral surface.

In copending application Serial No. 606,632, filed April 21, 1932, We have described andclaimed abrasive articles of the` class described wherein blocks of bonded abrasive material are attached to a flexible backing by a layer of resilient material oi a character and thickness such that the device is adapted to yield locally under the pressures applied in grinding, rubber being the pre- ,v .'ferred cement for the purpose. In certain embodiments of that invention a layer of :soft rubber is provided of sufficient thickness and resilience to permit the abrasive blocks to yield with respect to the backing material to which the soft rubber is attached.

-We have now discovered that certain synthetic resins such as certain polyhydric alcohol-polybasic acid condensation products or certain modified vinyl resins have the requisite combination of properties to be suitable for use in place of the soft rubber disclosed in application Serial No. 606,632 and that articles cemented with these resins exhibit grinding characteristics not attainable with rubber cements.

Understanding of our invention wiil'be assisted by reference to the accompanying drawing wherein:

Figure l is a top view of a portion of an abrasive belt or band employing one modification of our invention;

Figure 2 is a cross sectional view along the lines II-H of Figure 1;

Figure 3 is a top view of a portion of an abrasive belt or band embodying another modiiication of our invention;

Figure 4 is a sectional view along the lines IV `IVofFigure3;.

Figure 5 is a section of one form of a wheel embodying our invention; and

Figure 6 is a partial section of a modiilcation of Figure 5.

Referring to the drawing, the belts or bands of Figures 1 to 4 comprise a backing I to which are attached blocks of bonded'abrasive material I by a cement 2. In Figures 5 and 6 there is shown an embodiment of the invention wherein a band of the type illustrated in Figures 3 and 4 is mounted on a Wheel comprising a rigid core 4 with a peripheral layer 5 of resilient and yieldable material such as soft rubber.

/The backing I may be made of metal, fabric, leather or other suitable material but we prefer 1 to employ a one 'piece Jointless metal band such as a band of spun steel. -The backing must be suiiiciently iiexible to permit the band to bend and straighten out, as is required by a belt operv ating about pulleys or to yield slightly under and 2 as individually` formed blocks, may be made in any of the usual ways. For example, they maybe bonded with a ceramic, resin, rubber. silicate or other desired bond in ways well-known to vthe art. Similarly, they may be prepared by any of the known methods such'as by pressing, sheeting, tamping or the like, thus making it possible to furnish abrasive bands or belts in which the abrasive portion has the'characteristics desired. This adaptability of the invention to the use of various types of vabrasive bodies is a valuable feature of the invention as -it permits furnishing abrasive belts having any desiredgrinding characteristics.

Where blocks are formed by fracturing a vcontinuous body of bonded abrasive, such as are illustrated lin Figures `3 and 4, the abra.'- sive body may conveniently be formed as a continuous block of the required dimensions, ce-

mented to the backing, and then fractured tov` permit bending of the belt. This method ci' making bands is particularly adapted for use on backings-which can be straightened out` into a plane surface although it may be applied to cir-l cular bands by molding the abrasive as hollow cylinders of the required dimensions.

We have found that the choice of a cement 2 material is an important vconsideration in .the preparation of satisfactory belts. As will appear from a c'zonsideratio'n of the movement of a backing when it is used as a belt moving over two or ,more pulleys, the cement is subjected to rather severe stresses due to the continuedA and repeated curving and straightening of the backing.

for attaching the abrasive bodies to the backing layer of yieldable material such as soft rubber in order that the pulleys may absorb part of these stresses.

Because of these stresses the cement must be unusually strong and tough, highly adhesive to both the backing and the abrasive blocks, and resilient enough to absorb the stresses set up. A brittle cement, even though it has high tensile strength, is unsatisfactory because it cracks and allows the abrasive blocks to become detached.

The stresses imposed upon the cement are accentuated by the pressures applied through the work piece when the belt or band is in use.

We will now illustrate our invention with a number of specific examples, it being understood that the examples rare for illustrative purposes only and are not intended to be limitative.

Example 1 Abrasive sticks 2% inches long by inch wide` by 1/4 inch thick were made up with 80 grit fused alumina grain and 10% of a phenolic resin bond in the manner described and claimed in a patent to Harry C. Martin, No. 1,626,246. A 2%" x surface was coated with a rather thick solution in acetone of a modified vinyl resin having a softening point of about 150 C. and known as Alvar V H 70. This resin is prepared by hydrolyzing polyvinyl acetate and reacting the product with acetaldehyde as described in British Patent No. 351,082.

A steel band 2%" Wide, 515" thick and 12 inches in diameter was mounted on a pulley, its outer surface was sandblasted, and a thinner solution of the resin described above was applied to the sandblasted surface. 'I'he abrasive blocks were then mounted on the band with the cement-coated surfaces in contact with each other leaving 41 spaces between blocks, and a wet cloth was tightly tied around the assembly. Upon drying the-wet cloth shrinks and tightens.

The assembled band was dried for 24 hours at room temperature and for 48 hours at 120 F. to remove the solvent. It was then mounted on an expansible pulley provided with a peripheral layer of soft rubber', dressed with a silicon carbide brick and speeded to 2500 surface feet per minute. The band was used for grinding until the blocks had worn verythin without damage to the resin cement or dimculty from the blocks becoming detached.

Example 2 A band was prepared in a manner similar to for 16 hours.

Example 3 A band was prepared as described in Example 2 except that ceramically bonded sticks of silicon carbide were used instead of the resin bonded fused alumina of Examples 1 and 2..

As was pointed out above, our invention has the'advantage that it is adapted to use abrasive bodies of any desired composition. It has the added advantage over, the invention of our copending application that the resin cements provide a more rigid mounting than rubber and the Wheels and belts of the present invention therefore provide a grinding action not obtainable by a resiliently mounted block and yet one which is somewhat softer than can be obtained with the conventional rigidly bonded abrasive wheel.

Having described our invention and illustrated it with specific examples, we declare that what we claim is: g

An abrasive article comprising a flexible band,

`a plurality of blocks of bonded abrasive material attached to said band by a resin layer containing a major proportion of a synthetic resin, said layer being flexible enough to permit the band to bend between the blocks, and strong enough to retain the band flat against the blocks and to prevent the blocks Afrom yielding locally under the pressure of grinding.

CHARLES E. WOODDELL.

CHARLES S. NELSON.

-Rorv LINCOLN..

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