Patent GB-594088-A (GB)
Title: Improvements in or relating to the manufacture of cylindrical abrasive articles
IPC: B24D18/00
Filed: 1945-06-25
Abstract: 594,088. Abrasive rollers; flexible abrasive sheets. CARBORUNDUM CO. June 25, 1945, No. 16188. Convention date, June 27, 1944. [Class 60] [Also in Group VIII] A cylindrical abrading-member is made by piling sheets 6 of felted fibrous abrasive-containing web material, compacting the pile by pressure into a slab having a thickness at least equal to the diameter of the member to be produced, cutting a strip from the slab of a width likewise related to the diameter, and forming the strip into the desired cylindrical shape. The web-material may include an adhesive, and the compacting pressure may be applied with or without heat according to the nature of the adhesive. The final shaping may be done in a lathe. If abrasive wheels having arbor holes are to be made, rods 11 preferably wrapped in paper or given a coating to facilitate their removal after the compacting, are placed in central positions in the pile of sheets. Alternatively, the strips formed by cutting along lines 8 are centrally bored at one or both ends to receive a spindle. The web-material may be made as described in Specification 555,640, or the abrasive particles may be mixed with adhesive binder which is then applied to the web by a roller, or the abrasive material may be projected by an air blast into the web immediately before consolidation. The webproducing processes described in Specification 557,038 may be used, or paper-stock fibres with included abrasive may be felted. The abrasive is added in stages, with or without a coating of adhesive, whilst the fibrous web is still highly aqueous, the first-added grains sinking deeper into the web than do the additions made as the web becomes de-watered. Alternatively, the fluid fibrous suspension is collected on revolving foraminous supports, e.g. cylinders, partly immersed therein, the collected material being transferred to a moving endless felt belt at which stage the abrasive is added. The web is wound to the desired thickness on the upper roller. The paper stock may be agitated with gelatine and water-proofing compounds, antifriction agents, flexibilizers, plasticizers and other fillers may be incorporated in the web. In a process particularly described, web material produced as described in Specification 557,038 and containing approximately 75 per cent of fused alumina particles of 80-mesh grit-size, 15 per cent cotton fibres and 10 per cent natural rubber is sized with a 20 per cent aqueous solution of casein glue such as that sold under the Registered Trade Mark " Casco " to provide 10 per cent casein by weight based on the fibrous sheet material. Piled sheets of this webmaterial is pressed at 5000 1bs. per square inch at a temperature of 260‹ F. for 30 minutes for an inch thick slab. The slabs are then ovencured for 10 hours at a temperature of 260‹ F. Cutting, turning and end trimming are then effected. If a mounting spindle is to be inserted in a central drilled hole, it may be secured by a cold-setting cement, or preferably by a heat-hardenable cement, such as that produced by mixing a thermosetting liquid phenolic condensation product with a suitable filler such as powdered quartz. Specification 562,851 also is referred to.