US2339208A - Flexible abrasive product - Google Patents

Description

- Jan. 11; 1944.

E.- VAN DER PYL FLEXIBLE ABRAS IVE PRODUCT Filed April 4, 1941 EDWFIE'D VH/V DER PYL Patented 11, 1944 2,339,208

UNITED STATES PATENT orrice FLEXIBLE ABRASIVE PRODUCT Edward Van der Pyl, Holden, Mass; assignor to Behr-Manning Corporation, Troy, N. Y., a corporation oi Massachusetts Application April 4, 1941, Serial No. 386,785

3 Claims. (01. 51-309) The invention relates to flexible abrasive Y be selected with particularregard to the-abradproducts. ing operation to be performed. For example, One object of the invention is to provide a for the cutting or polishing oi" hard carbides, i'lexible abrasive product of great tensile diamond abrasive will preferably be used. For strength. Another object of the invention is to 5 most operations upon tough steel, fused alumina provide a fiexibleabrasive product capable of abrasive will be used. For woodworking oper-" use' at high temperatures, for example, in a ations, silicon carbide and in some cases garnet furnace. Another object of the invention is to may be used. l provide an abrasive belt: of very rugged con- The abrasive H is to be bonded to the cold struction, which is durable under extreme conrolled steel backing ill by a metal bond formed ditions such as excess of heat or cold, which from metal powder l3 contained in a hopper It. may be used wet or dry, and which has great Within the scope of the invention, any powders tensile strength. Another object of the invenor mixture of powders may be used. However, tion is to provile a flexible abrasive belt utilizto obtain resistance to heat, high melting point ing diamonds which are so firmly attached to a I! metals will be utilized, that is, melting at above durable support that their efiective abrading 250 '0. Because they can be obtained in very life may be substantially utilized. Other obfinely divided form and in a relatively pure state. jects will be in part obvious or in part pointed except for possible oxidation in certain instances,

I out hereinafter. electrolytic "metal powders are preferred. For

The invention accordingly consists in the fea- 2o satisfactory results for the bonding of most tures of construction, combinations of elements. abrasives, bronzes are desirable which can be arrangements of parts, and in the several steps formed-iii situ from a mixture of copper and tin i and relation and order or each of said steps to powdersl If a ductile bronze is wanted. and 1 one or more of the others thereof, all aswill this may be preferred for certain uses, 5to be ill stra iv d scri ed herein. nd he scope as Orrin, the remainder copper. may be utilized.

' of th application f Which w be indicated in If a friable copper bond is wanted, and in many the follow n claimssituations'thi's preferred, above 18% an In the ac omp n i rawi i r ing one preferably not more than of tin, the reof many possible embodiments of the mechanimainder copper may be employed. I may use in 1 fea u s of the invention, :10 certain instances the very hard copper-iron-tin- Figure 1 is a view, partly in elevation and nickel bond'in any of its embodiments described partly in section, of apparatus to make the flexi my U. 3. Letters Patent No. 2,238,351. Howlble r ive Pr d t, and ever, any other metals or alloys may be-empl'oyed M 2 is a cross sectionalview, on 1- within the scope or the invention, such as those larged scale, of a flexible abrasive product. 5 disclosed in Milligan Patent 2,077,366, my own P 'OVid a q a y of sheet'meta D prior Patent 2,077,345, and others.

y n a 1011. n sh wn- 0 rolled, Steel n l The sheet l0 travels in the direction of the (sheet form is preferred n h re re o parrrow from right to left. It first, passesunder tiwlar limits t e thickness e t the hopper it where itreceives a load of metal eve it may be no ed' t at or ostp se h 40 I3 which becomes a level deposit l3a extendsteel shoul be f ir y flexible a Since e p ing the entire width of the sheet iii. A spreader cipa utili of t e invention is to form abrasive guard l5 levels the deposit and spreads it evenly, I belts. the thickness of the steel will have a rela- Any lost oil the edges may be recovered. and tion to the size of the rollers over which the belt used r again, It, i advisable not to try to runs and a general relation-to the character of run thesheet It! too fast: two or threefeet a the abrading operation whether, for example, it minute is a, satisfactory speed, involves fast removal of larseainounts oi stock' The sheet ill with a layer 13a thereupon then without any attemptto obtain other than a comes under the hopper I! having an abrasive rough abrading operation 01 whether, 0!! the delivery roll it and a guard II. The roll I6 is other hand, it may involve a fine polishingiacrotated slowly to deliver a steady waterfall oi tion. A typical sheet of cold rolled steel isin abrasive Ila, forming 'a-level superimposed layer 3 dicated at i0, Figure l, and this to be coate of abrasive lib on top of the layer l3'a. Preferwith abrasive ll contained in a hopper l2. ably the adjustments of the hopper, guard and Within the scope of the present invention the delivery roll l6 are such-that the layer lib will abrasive. ll may be of any suitabletvpe and will 68 only be one abrasive particle thick and the inapart. The technique of hopper delivery for abrasives is now well understood so I need not further describe the same.

The sheet III with layers l3a and l lb now passes) between rolls 20 and 2!. The roll 20 is preferably a polished steel roll. The roll 21, on the other hand, is preferably a resilient rubber roll. The roll 20 may have trunnions or an arbor 22 mounted in hearings in a pair of frame members 23 of the general shape shown. The lowersteel roll 20 is a fixed roll while the upper rubber roll 2| is adjustable-in a vertical direction. It has trunfifiiais or an arbor 24 by means of which it is lled in a pair of vertically movable slides 25 sliding in guideways 26 formed in the frame 23. Screws 2! extending through the top portions of the frame 23 can be used to force downwardly the slides 25 to adjust the pressure.

The action of the rubber roll pressing against. the layers lib and Ba upon the sheet In compacts the metal layer 'l3a but the larger abrasive particles form for themselves temporary pockets in the rubber. Nevertheless the abrasive particles are forced downward until they contact the sheet ill but their tops protrude above the compacted level of the metal powders. The delivery rates of the metal powders and the grit size of the abrasive l I should be so chosen that suflicient embedding of the abrasive will occur leaving, however, a substantial volume of the abrasive above the surface. The exact proportion of abrasive embedded and above the surface will var for different uses and if the known abrasive cloth technique is followed, practical and useful results will be achieved but variations will, of course, suggest themselves for further improvement.

The sheet ill with compacted layer 13a. and abrasive particles lib embedded therein now passes into a furnace 30 and is there heated to such temperature and for such a period as will cause the metal particles of the compacted layer i3a to fuse, alloy or sinter together to form a strong, rigid and yet somewhat porous structure,

' at the same time to be strongly and directly bonded to the steel sheet III. It is preferable to plate the sheet ill by immersion-plating with a asaaaoe to the desired sintering temperature, which will be around 600' C. for the copper-tin mixtures mentioned and around 850 C. for the coppertin-iron-nickel mixtures, for example,.equal parts by weight of these metals. In Figure 1 of the drawing, the inlet pipe 3| admits gas to the sintering chamber. An entrance slot 32 for the steel sheet In with superimposed layers is only high enough to admit them with slight clearance and the volume of gas entering the furnace 30 is such that there is an outfiow at the slot 32. The furnace has an exit slot 33 through which the material being treated passes into a water cooled chamber 34 consisting of water jacketed walls 35 having awater entrance pipe 36 and an outflow pipe 31. The gases from the furnace 30 pass into the cooling chamber 34 and thence out a narrow exit slot 40 for the material which after leaving chamber 34 may be wound upon a drum in a customary manner. furnace 30 may be heated by suitable electric heating units 4| or in any other desired manner.

The final article illustrated magnified in Figure 2 constitutes an abrasive sheet consisting of a metal backing I!) (which need notnecessarily be steel) and abrasive grains ll secured thereto by a sintered metal bond l3 which is fused to the metal backing In. For firm embedding of the abrasive particles, more than half of their volume may be embedded, as shown in Figure 2. For long life of the abrasive article, a friable bond I3 can be employed and I have already indicated which are good friable bonds, for example, copper-tin with more than 18% of tin. For a very strong and hard, yet somewhat friable bond quite suitable for diamonds, equal parts of copper, tin, nickel and iron may be used. This bond also adheres very tenaciously to the iron backing and is the preferred embodiment of my invention. Such a bond is highly useful for holding diamonds because it will hold them until they have been completely used up. When the diamonds wear coating which may be terne plate, lead, tin, or

other suitable soft metal alloy plating. This dur-,

ing the sintering operation in the furnace 30 is absorbed intothe metal layer formed by sintering,

the layer 13a. However, this preliminary plating operation appears to facilitate the union of the metals. But the strength of the union between the steel sheet l0 and the metal layer l3a is far greater than the strength of the'soft metal and the heat resistance of the final article is not merely that of the metal plating but is far, far

above it. v

The sintering should take place in a reducing atmosphere within the! furnace 30. Such reducing atmospheres in sintering furnaces are now well known and need not be illustrated and described in much detail herein. A suitable reducing atmosphere consists of fiue gas made by incompletely buming natural gas and having from 1% to 7% CO. 7% to 11% C02, 1% to 7% hydrogen, and as little water vapor as is practically possible, for instance, about three-tenths of a pound of'water vapor per 1000 cubic feet of the most daily use.

down to the level of the bond, the bond will start to crumble away sufllciently to clear the abrasive for cutting if enough pressure is used. When diamonds are the abrasive, the atmosphere in,

the furnace 30 should preferably be nitrogen, which is easy to procure, non-poisonous, and which will prevent oxidation of the diamonds.

Abrasive belts can be made out of the material of the invention and if they are backed by strong supports and driven by powerful rollers, diamond abrasive belts will cut the hardest of, carbides and last through all vicissitudes for years of al- Abrasive belts constructed according to the present invention, especially if the abrasive is fused alumina, may be run through slots into hot furnaces to do. an abrading. operation upon white hot metal.

It will thus be seen that there has been provided by this invention an article of manufacture and a method in which the various objects hereinabove set forth together with many thoroughly varied in various parts, all without departing from flue gas. The water vapor in the flue gas may be removed by refrigerating the flue gas and thereby condensing the wate The dried flue gas is then passed into the furnace 30 where it is reheated the scope of the invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim: l. A flexible sheetelike abrasive article comprising abrasive granules embedded in a porous ma- The sintering trix of a. sintered metal bond comprising a copper and tin alloy having from 18 to 35 percent of tin, secured on a flexible sheet metal backing, said sintered metal bond being of a porosity permitting the product to flex readily in use.

2. A flexible sheet-like abrasive article comprising abrasive granules embedded in a porous matrix of a sintered metal bond comprising a copper and tin alloyhaving more than 18 percent of tin.

secured on a flexible sheet metal backing, said 10 sintered metal bond being of a porosity permitting the product to flex readily in use.

tered form suflicient porosity to permit flexing of the resultant product.

EDWARD VAN DER PYL.

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