GB407978A - Improvements in or relating to abrasive coated materials - Google Patents

Abstract

407,978. Emery cloth, sandpaper, &c. TENNANT, W. J., 111, Hatton Garden, London.-(Behr-Manning Corporation; Troy, New York, U.S.A.) Sept. 28, 1932, No. 26923. [Class 60.] In the manufacture of abrasive coated materials, fur example, emery cloth, sandpaper, &c., the abrasive grains, which have been rendered magnetically responsive, are subjected to the action of a magnetic field., whereby the disposition of the grains on the carrier is controlled; in addition, the grains may be subjected to the influence of an electrical field. The grains of abrasive are first coated with a moist adhesive to which is applied finely pulverized iron or steel, the grains then being placed in a receptacle 4 having a wire mesh bottom 5 and agitated by means 6 so that the grains fall on to paper &c. 7 coated with adhesive, and held by rolls 3 upon a thin brass, or other non-magnetic, table 2. Beneath the table 2 is an electromagnet 1, the field of which causes the falling grains to turn with their longest axes approximately perpendicular to the paper 7 ; an electrostatic field, as described in Specification 378,014, may be used in conjunction with the magnetic field. In a modification, the grains are fed on to a moving belt and pass beneath the downwardly facing adhesive-coated surface of the paper &c., being attracted upwardly thereto by an electromagnet placed above the paper, or by the combined action of the magnet and an electrostatic field ; surplus grains, in this case, do not reach the paper. In order to cause stratification of the grains according to size, the grains fall from a receptacle 5, Fig. 5, past an electromagnet 1, giving a horizontal field, onto the paper 7. In a further modification, the paper sheet may first have deposited thereon the grains of abrasive, and then be moved through the magnetic field before the adhesive has set.