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May 11, 1937~ H. w. H. BETH 2,079,787~ PULPSTONE _ Filed Aug. 12, 1936 ‘ VA 317 H 2 . I‘?! - " w a ggmm Hugo ' W H. BETH Gum“, Patented May 11, 1937 2,679,787 UNITED STATS PAT T FFICE 2,079,787 PULPST‘ONE Hugo W. H. Beth, Worcester, Mass, assignor to Norton Company, Worcester, Mass., a corpora tion of Massachusetts Application August 12, 1936, Serial No. 95,503 4 Claims. (Cl. 51-207) The invention relates to pulpstones. One object of the invention is to provide an improvement in the type of pulpstone disclosed in United States Letters Patent Reissue No. 5‘ 19,678 to R. C. Benner and H. E. Stowell. An other object of the invention is to avoid frac turing of the sectors of a pulpstone by reason of differential thermal expansion thereof. An other object of the invention is to provide an ef 10 ?cient construction for a pulpstone. vi Other ob jects will be in part obvious or in part pointed out hereinafter. The invention accordingly consists in the fea tures of construction, combinations of elements, and arrangements of parts, as will be exempli?ed in the structure to be hereinafter described and the scope of the application of which will. be pointed out in the following claims. In, the accompanying drawing, the single fig ure thereof represents an axial sectional View of one-half of a pulpstone constructed in accordance with the invention, together with the mounting shaft and ?anges. , In the illustrative embodiment of the inven 25 tion I provide a pulpstone construction which, with the exception of the feature to be speci?cal ly pointed out hereinafter, may be substantially the same as that disclosed in the Reissue Pat ent No. 19,678 to Benner and Stowell above re 30 ferred to. For example, I may provide an outer body or annulus l of abrasive annuli 2 each one of which comprises a plurality of sectors. I may further provide an inner portion 3 of concrete or other material as disclosed in the aforesaid Ben 35 nor and Stowell patent. I may further provide driving ?anges 5 in threaded engagement with a driving shaft 6 and I may provide a pair of metal facings ill. I may further provide reinforcing rings or 40 hoops 8 such as disclosed in U. 8. Letters Patent to Bonner and Soley No. 1,975,970. ‘These may be surrounded with material 9 of any of the formulae disclosed in the patent last above iden ti?ed- I may use any other features in either of 45 the two- patents mentioned not inconsistent with each other, and the accompanying drawing clear ly discloses the illustrative embodiment of this invention so far as constructional features are .50 concerned. Pulpstones constructed in accordance with the patents above identi?ed have been found in ac tual practice frequently to fail in service by the fracturing of one or more end sectors of the annuli identi?ed in the accompanying drawing by the references 2a. I have found that this oc 15.5 curs despite careful balancing or attempts at bal ancing coei?cients of expansion, for the reason that some portion of the abrasive annulus I is rigidly held between the ?anges 5, 5 while the outer portion of the abrasive annulus l is free to expand, and moreover the heat generated dur ing grinding is generated at the periphery of the wheel and there is, during grinding, a thermal differential in the annulus I from the peripheral outside to the inner portion. It is probably true 1H 0 that no metal parts of the shape of the ?anges 5 can resist a direct thrust due to thermal ex pansion. Nevertheless,\ the pressure of the flanges 5 is a factor inso- much as axial expan sion of the outer portion of the annulus ‘I would otherwise force axial ‘expansion of the inner portion, even though cold, by reason of the integral connection. While the ?anges 5, 5 might not be able to resist a direct thrust from thermal axial expansion of the inner portion of 20 the abrasive annulus I, they can resist axial ex pansion of this inner portion of the annulus (in side the rings 8) by reason of thermal expansion of the outside portion of the annulus (outside of the rings 8) because this force can be no greater 25 than the shearing strength of the abrasive annuli which is weakened at what I term the throats, H. As partly explained .in the patents referred to, there is great force exerted by the ?anges 5 upon the pulpstone in an axial direction. This is 30 due to the right and left~hand threads on the shaft 6 which are so disposed, with relation to the direction of rotation, that rotation of the pulp stone and consequent resistance due to grind ing at the periphery tends to tighten the ?anges 3 5. A pulpstone may, when it is started up, be quite cold. As it is started, the full load is placed upon the annulus l and this tends to tight en the flanges 5 on the, shaft 6, the shaft 6 being at that time cold. The periphery of the annulus I heats up ?rst and becomes quite hot even down to the rings 8 while the rest of the stone, includ ing the flanges 5 and the shaft 6, may still be quite cold. It will be understood that condi tions met with in practice vary considerably and 45 the foregoing is a conservative statement of what happens when a pulpstone is started and, for one reason or another, the water gives out soon after the start of the grinding operation. Under such conditions, temperatures way above the boil- 50 ing point of water may be reached and trans mitted to the entire outer portion of the an nulus i. As the annuli 2 and 2a, are heated, those annuli at the center or near the center do not ?rst frac- 55 2 2,079,787 ture, as the pressure is more or less the same on both sides. The worst condition is met with at the annuli 2a. and, therefore, in actual practice, these are usually the ?rst to go. It will be seen 5 that the annuli 20., so far as the outer portion outside of the rings 8 is concerned, are absolutely unsupported, on the outside (in an axial direc tion) , while from the inside (in an axial direc— tion) they are subjected to the sum of the ex l0 pansions due to the coei?oient of expansion of the material times the number of degrees of tem perature differential times the axial length of the annulus 1 inside the outside annuli 2a. As these same annuli 2a are rigidly held inside of 15 the rings 8, a leverage is produced which fre quently fractures them. I correct this condition by providing com~ pressible ?llers I2. Preferably I use a material different from that disclosed for the embedding 20 material 9 in Patent No. 1,975,070. This ?ller material I2 need not have any function so far as holding the sectors together in an axial direc tion is concerned. This function is sufficiently achieved by the construction otherwise disclosed 25 and disclosed in the patents referred to. While it is suf?cient, so far as conditions usually met with in practice are concerned, to provide ?llers I2 which have the shape of annular disks, or Other materials for the ?llers I2 and I3 may be used. For example, a Babbitt metal ?ller with compressible posts made according to the disclo sure of United States Letters Patent No. 1,815,108 to Larsson may be substituted. The function of the ?llers I2 and I3 is to deform under pressure, whether or not these ?llers return to their in itial condition after the particular stress or strain has been relieved and the stone returns to a state of thermal equilibrium. 10 In the drawing I have shown the ?anges 5 and the metal facings I0 as slightly larger in diameter than in the reissue patent to Benner and Sto well above referred to in so much as, due to the provision of the compressible ?llers I2 and I3, the 15 ?anges 5 may be extended outwardly and by do ing. so differential strains if the heat ever pene trates to the interior portion of the annulus I are better avoided. By extending the metal parts further outwardly, a directthrust which 20 will deform the metal is achieved by the thermal expansion and this to some extent reduces what I term the leverage effect of the expansion. This leverage effect is due to holding the material at the inside and providing a condition where 25 thermal expansion creates a turning couple at the outside of the annulus. There is a certain resiliency to the material 9 which su?iciently ' sectors thereof, I may also provide ?llers be overcomes the leverage effect so that the con 30 tween sector blocks in a circumferential direc tion, as indicated by the reference character I3 at" the central portion of the annulus I. The Single ?gure will be understood to be an axial struction illustrated in the drawing ful?lls prac sectional view of the embodiment of the inven 3 tion in which both types of ?llers are used, dis closing ?llers I3 which extend in axial planes at the central portion of the drawing, the section plane being broken. In the preferred embodi ment of the invention both the annular ?llers I2 40 and the axial ?llers I3 will be provided, but so far as certain features of the invention are con cerned and under certain conditions of operation only the ?llers I2 will be used. It will be understood that so far as practical 45 requirements are concerned, it is sufficient to safeguard the pulpstone against certain stresses and expansions without safeguarding it against all. In fact, considering each abrasive sector as a unit, if the outer portion be heated up and 50 the inner portion be not heated, there is a cer tain strain set up in the sector itself which no amount of mechanical device outside of the sec torlpossibly could completely overcome. Never theless, abrasive material is suf?ciently elastic 55 to withstand a certain amount of such strain. It is the unsupported and multiplied strain and stress due to di?erential expansion as herein above explained which this invention relieves. Considering now the material for the ?llers I2 60 and I3,.I prefer to use a compressible and de formable composition. One example of a com position which might be used is as follows: Percent by weight Rubber _______________________________ __ 45.6 65 Sulphur ______________________________ __ 24.6 80 grit size silicon carbide _____________ __ 4.8 16 grit size cork _______________________ __ 25.0 The above formula may be widely varied. For 70 example, the following may be used: Parts by weight Rubber ________________________________ __ 5O Sulphur ________________________________ __ 27 Silicon carbide __________________________ __ 23 75 Cork ____________________________ ___ ____ __ 44} 30 tical requirements. However, so far as many fea tures of the invention are concerned, the flanges 5 have the same relation to the abrasive an nulus I as is disclosed in the aforesaid patent to 35 Benner and Stowell. The joints into which the ?llers I2 and I3 are placed may be of the order of a quarter of an inch wide. With the use of a different ?ller material, spaces of different width may be provided. I may provide abrasive segments of zigzag con tour in developed view, as disclosed in U. S. Let ters Patent No. 1,469,723 to Greenwood, but on the other hand due to the narrowness of the ?llers I2 and the fact that there is some abrasive grain in the composition, the faces of the sectors may be in radial planes perpendicular to the axis. Considering now the manufacture of the en tire pulpstone, it may be assembled according to previous practice, laying the ?ller material I2 and I3 in position as the sectors are assembled. Then by means of a single heat treating opera tion, the ?llers I2 and I3 as well as the material 9 may be vulcanized, and at this same time other material which is thermally set in accordance with the disclosure of the patents to Benner and 55 Stowell and Benner and Soley may be heat treat ed. Other procedures currently in use or which may be adapted to the circumstances may be em ployed in the assembly and construction of the stone. It will thus be seen that there has been pro vided by this invention an article in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible em 65 bodiments may be made of the above invention and as many changes might be made in the em bodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted 70 as illustrative and not in a limiting sense. I claim:— 1. In a pulpstone construction, a shaft having right and left-hand threads, ?anges mounted on . the shaft in threaded engagement with said 2,079,787 threads, an inner portion to the stone extending around the shaft and radially smaller than the ?anges so that the pressure of the ?anges may be exerted beyond the inner portion, sectors ar ranged in the form of an annulus and around the inner portion, reinforcing rings embedded in the sectors, the sectors abutting each other in an axial direction inside of the rings and at that portion receiving the thrust of the ?anges, and 10 ?llers of material which Will deform under pres sure between the sectors, from end to end of the stone, outside of the rings. 2. In a pulpstone construction, a central sup port, a series of abrasive annuli each comprising 15 a plurality of sectors mounted on said support, inner portions of said sectors being in abutting engagement axially, and outer portions of said sectors being spaced, and compressible ?llers be tween said outer portions. 3 3. In a pulpstone, a central support, a series of abrasive annuli on said support, each annulus comprising a plurality of separate blocks, each block being in part at least substantially a sec tor and each block being wider in an axial direc tion at the inside adjacent the support than at the outside adjacent the periphery, means holding the blocks together axially, and means holding the blocks on the support radially. 4. In a pulpstone, a central concrete support, 10 a series of annuli of abrasive blocks on said sup port together forming an abrasive annulus, each of the series comprising substantially sectoral blocks, and metal rings between individual an nuli of the series of annuli, the blocks being in non-compressible relation inside the rings, and the blocks being spaced outside the rings. HUGO W. H. BETH.