Abrasive-covered material and the like

Application filed November 23, 1925. Serial No. 70,743.

My invention relates to abrasive material as exemplified for instance by the conventional emery cloth, sand paper and other devices in which abrasive grains constitute 5 the abrading medium. In practice it has been recognized that material of this class in which the abrasive grains are arranged as continuous abrading surfaces, quickly deteriorate in use; for instance, such continuin ous abrading surfaces quickly become glazed due to the fact that the spaces between the abrasive grains become clogged up with particles of the material being abraded, whereby the grinding or polishing proper15 ties of the abrading surface are destroyed. Attempts have been made to overcome this condition by providing the active surfaces of the material with alternate coated and uncoated portions. In an existing method 20 this result is attained by deflecting a falling sheet of abrasive grains in a manner of strewing said grains upon a sheet in separated rows. This method is unreliable because of the fact that definite control of the falling 25 grains is lacking and no positive precaution is provided to prevent the grains from reaching those parts of the sheet which are intended to remain uncoated.

The object of. the present invention is to 50 provide a novel and efficient method whereby an abrasive material is produced, in which the active surface comprises alternate abrasive and non-abrading portions positively defined with respect to each other in a 35 predetermined manner. Other objects will appear from the description hereinafter and the features of novelty will be pointed out in the claim.

In the accompanying drawing, which 40. shows examples of the invention without defining its limits, Fig. 1 is a diagrammatic view illustrating the method in one of its forms and Figs. 2, 3 and 4 are face views of abrasive sheets produced in accordance 45 with the novel method. For the purposes of illustration and description the method has been shown as applied to sheets of the class exemplified by emery cloth and sand paper. It will be understood that this is 50 not intended to define the limits of the invention and further that the novel method is capable of efficient use in connection with the production of any type of abrading material in which abrasive grains are bound 55 together by means of a suitable binding agent

In carrying out the novel method, under such conditions a coating 10 of glue or other suitable binders is applied in a predetermined manner to a surface of the material, illustrated in the form of a sheet 11 such as paper, cloth and the like, which thus constitutes a backing. For instance, the surface of the sheet may be completely covered with the binder 10 in which case a coating of abrasive grains 12 is applied overall to said binder 10, while the latter is still unhardened so as to completely cover the same. Portions of the combined adhesive 10 and grains 12 are then removed for instance, by 70 scraping, at predetermined points to produce alternate abrasive portions a and non-abrading portions δ. The aforesaid scraping operation may be accomplished for instance by means of a suitable comb 13 reciprocated 75 in any convenient manner; in this way the binder, to a predetermined extent and the abrasive grains are removed simultaneously along a plurality of .parallel spaced lines. By properly controlling and guiding the 80 scraping comb 13 the aforesaid lines along which the removal of the material takes place may be straight, undulating, zig-zag or otherwise to produce corresponding lines of spaced abrading strips a on the surface 85 of the sheet; it will be understood that the term “undulating lines” as used in the claims is intended to cover any line other than a straight line. Thus the scraping comb may be actuated to produce the results illustrated in Figs. 3 and 4. If desired, the removal of the material may be accomplished by two scraping combs having reciprocating movements, the paths of which intersect each other, and reciprocated in properly timed 95 relation. In this way, a result such as shown by way of exampierin Fig. 2 is produced upon the backing sheet 11. It will of course be understood that the removal of the material takes place before the binder 10 has set 100 or hardened.

The results set forth above may be also obtained by removing portions of the binder 10 from the sheet 11 before the abrasive grains are applied; in other words in such 105 case a predetermined pattern, in binder, is first produced upon the surface of the material 11. While the binder pattern is still unhardened, the abrasive grains 12 are applied to the material, these grains adhering 110 to the material 11 only along the lines of the binder pattern.

1,067,784 the abrasive grains are fixed upon the material, cloth or other material or upon any other predetermined surface by means of a suitable adhesive or other bond. Furthermore, in all of the forms of the improvement, sand grains or other abrasive grains, either in bands or groups, lie in a keyed, mortised, or wedged relation to one another, thus creating a holding power and adhesion of the sand or other abrasive grains to the material equal to that which is present in surface coated abrasives coated in the ordinary manner. This holding power is materially greater than in the case of. abrasive covered sheets or the like in which the sand or other abrasive grains are strewn over the surface; in such case the grains lie in an open arrangement relatively to each other, . and are not keyed, mortised or wedged by ¢5 other grains of sand. In addition to this an abrasive material produced in accordance ί with my improved method provides definite

I is varied; these definite patterns may be 70 chosen and easily produced to obtain any desired abrasive angles suitable for varying classes of work.

Various changes in the specific forms described may be made within the scope of the claim.