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Feb- 12, 1963 |_. HORNBOSTEL 3,077,310 PULPWQOD GRINDING APPARATUS Filed Dec. 51. 1959 22 7/5 Z/ya/ f/arn basis! United States Patent 0 M1C6 artists Patented Feb. 12, i953 1 3,077,310 Lloyd Hornbostel,‘ Eeloit, Wia, assignor to ltleloit iron 2 in abrasive engagement with pulpwood supported by said PULPWOOD‘ GRINDHNG APPARATUS pocket, producing as among the advantages reduced stone ll’orirs, Beloit, Wis, a corporation of Wisconsin Filed Dec. 31, 1959, is‘cr. No. 863,295 2 Claims. (Cl. 241-280) Another object of the instant invention is to provide apparatus for grinding pulpwood to obtain pulp there— from, comprising a rotatable grinding member, a hous~ ing for pulpwood positioned adjacent said grinding mem ber, force applying means for advancing said pulpwood into grinding contact with said grinding member, and The present invention relates broadly to the art of wear. pulp production, and is more particularly concerned with novel method and apparatus for grinding pulpwood fea 10 means for effecting relative movement between said turingmovement of a pulp stone and pocket relative to grinding member and housing to vary the contact area one another, whereby there is obtained'pulp of consistent of said member in abrasive engagement with said pulp ly uniform quality at substantial power economies. wood, whereby frequency of sharpening of said grinding Since the advent of the early pulpwood grinders using member and the magnitude of grinding pressure varia j-ackscrews and a car jack for maintaining pressure and 15 tions to attain quality control are reduced. down to the modern high production magazine grinders A further object of the invention lies in the provision and continuous grinders of the ring or chain feed types, of a method of grinding pulpwood, which comprises ad it has been found dif?cu'lt to produce consistently uniform vancing a plurality of pulpwood sticks into abrasive en pulp. One explanation for this is the great number of gagement with a rotatable grind member. variables in the pulping process, and among those of Other ‘objects and advantages of the invention will considerable importance are the‘ sharpness of the pulp become more apparent during the course of the following stone, the moisture content of the pulp wood and the description, particularly when taken in connection with pulpwood density. To explain, an accepted control used in the manufac~ ture of pulp is “freeness” or measurement of the drainage characteristics. Since all pulp is at one time in a sus the accompanying drawings. In the drawings, wherein like numerals designate like parts throughout the same: FIGURE 1 is a top plan view of the apparatus effec pended form, in order to make a sheet of paper the water tive to practice the instant method, and incorporating must be removed, and'theease or lack of ease with which a conical grinding member and a pulpwood pocket which this mixture, or slurry,,will drain is referred to as free— is moved laterally with respect thereto; ness or slowness. A free stock is usually composed of 30 FIGURE 2 is a fragmentary end View ‘to illustrate the relatively long, coarse ?bers, or is a stock from which grinding action on a pulpwood stick at the relatively the ?nes or ?ours (gelatinous bits of fractured ?bers) larger radius of the conical pulp stone of FIGURE 1; have been removed; while a :slow stock generally con and ' sists of short, ?ne, well-?brillated ?bers intermixed with FIGURE 3 is a view similar to FIGURE 2 and show ?nes. Now, in pulp grinding, freeness changes markedly from the time of sharpening the pulp stone until sharpen~ ing is again required. The sharp stone tends to cut the ?bers and decrease‘the‘?nes, whereas as‘the stone be ing the grinding action at the relatively smaller radius of the conical grinder stone. As earlier stated, it has been dif?cult in the past to obtain consistently uniform pulp quality at reasonable comes worn, the extent of cutting decreases and the rub power expenditures, due to the greater number of vari bing and re?ning action has the e?ect of producing more 40 ables involved in the pulpwood grinding process. The ?nes and greater ?brillation‘; freeness or measurement of pulp drainage characteristics The variable of pulpwood‘ moisture content bears im changes substantially from the time of stone sharpening portantly on the‘ e?iciency of‘ the pulping operation, until it again becomes necessary to sharpen said stone, since when the wood is relatively wet the ?bers separate since it is now known that a sharp stone tends to cut more easily, their strength'is greater and ‘the power con the?bers and decrease the ?nes, whereas as the stone sumption is lower. While eitorts are made by soaking becomes Worn, the amount of cutting decreases and the or like procedures to have at least 30% moisture content, rubbing and re?ning action tends to increase, producing it is apparent that this condition cannot always be attained more ?nes and greater ?brillation. On the other hand, and a uniform moisture content for a particular load of the variations in pulpwood moisture content and density 50 pulpwood cannot be e?iciently accomplished, even when require that the grinding pressure or unit loading be pre-soaking is used. varied, and by reason of the relatively great contact area Accordingly, to compensate for moisture content and of the conventional grinder pocket, wide pressure varia density variations, while striving for consistently uniform tions or large changes in loading are necessary. This pulp quality, the grinding pressure or unit loading is ad markedly increases the total power requirements for the justed or varied. The pulpwood pocket, however, of grinding process, and a point is approached at which the prior art presents a relatively large contact area both mechanical pulp grinding loses some of its economical arcuately and axially, and the power requirements to vary attractiveness. the loading are therefore substantial. As is known, the It has now been discovered that uniformly consistent e?iciency of the pulping process is expressed in terms of pulp quality at minimum power expenditures is ob 60 horsepower per daily ton of ?ber, and it can therefore tained by varying the contact area of the pulp stone and be seen that when wide variations in grinding pressure pulpwood relative to one another, so that pulp stone Wear or load required to obtain optimum unit loading for is reduced and the stone remains in relatively sharp con consistent pulp quality are necessary, the pulping ef dition for a longer period, and thereby continues to out ?ciency is substantially diminished. It is accordingly an important aim of the present inven 65 rather than rub the ?bers. The relative movement described can be accomplished tion to provide method and apparatus for pulpwood grind ing productive of uniformly consistent pulp quality at minimum power requirements. by moving the grinder pocket laterally with respect to a generally conical grinder stone, or in other Ways which will become immediately apparent to those skilled in the Another object of this invention lies in the provision of improved structures and procedures for producing 70 art upon a consideration of the instant disclosure. The apparatus is illustrated in FIGURE 1 and is close pulp, wherein the pulp stone and pocket are moved rela ignated therein generally by the numeral Fill. As shown, tive to one another to vary the contact area of said stone 4 3 there is provided a pulp stone or grinding member 71 of parallel with the pocket and sticks being abraded, con generally frusto-conical con?guration supported for rota voluted pulp stories may of course be employed and in this case the motion of the pocket can be relatively slower and the power requirements would of course be reduced. tion at opposite ends by shaft means 72a journaled in bearing means 73——73a, respecdvely, said pulp stone 71 being driven in rotation by motor means or the like '74} having shaft means '75 coupled at ‘7'6 to shaft means 77 received in the bearing means 730. To vary the grinding contact area, a grinder pocket or housing 73 is provided with guide means 79 received in This and other variations and modi?cations, including tie use of more than a single grinder pocket for each pulp stone, may of course be practiced without departing from the novel concepts of the present invention. 1 claim as my invention: 1. Apparatus for grinding pulpwood to obtain pulp track means disposed generally parallel to the grind 10 therefrom, comprising a generally frusto-conical grind ing surface of the conical grinder 71. The pocket 78 ing member, means for rotating said grinding member, is laterally reciprocable along the track and suitable a housing for pulpwood positioned adjacent said grind motive means for this purpose may take the form of a ing member, force applying means connected to said double acting cylinder having ports 6“? \Lw and 33 admit housing for advancing said pulpwood into grinding con ting pressurized ?uid to opposite sides of a piston 845. tact with said grinding member, track means disposed having a rod portion connected either directly to generally parallel to the surface of said grinding mem the grinder pocket 78 or to the guide means '79 thereon. ber and receiving said housing for movement .therealong, Pulpwood (not shown) in the pocket ‘it? is urged into and motive means reciprocating said housing along the abrasive engagement with the conical grinder 71 by means shown in FIGURE 1 as comprising a cylinder 20 track means and laterally with respect to said grinding 35 provided with ports 3% and S7 to reciprocate a piston ti?» with arm portion connected to plate means 8% bearing against the pulpwood sticlzs. member to vary the location of grinding contact of said member with said pulpwood, whereby frequency of sharp ening of said grinding member and the power require ments to effect grinding are reduced. Buring lateral movement of the grinder pocket 78 2. A pulpwood grinding mechanism comprising in com along the track 89, the pulpwood sticks in the pocket 25 73 are continuously subjected to a changing stone radius, in the manner indicated in FEGURES 2 and 3. The bination a grinding rotor having a generally frusto-coni pulp stone ‘71 has a relatively large radius end 71:; and a relatively smaller radius end 7122 between which the the rotor in rotation about its axis, a support for pulp pulpwood sticks continuously travel under action of the motive means 81 for the grinder pocket 78. By reason of the continuously changing grinding surface in abrasive engagement with the pulwood, no single area or band along the pulp stone is subjected to greater Wear, and the stone 71 accordingly longer retains a good “tooth” and the fibers from the pulpwood are cut, rather than cal grinding surface, rotating driving means for driving wood adjacent said grinding surface for holding pulp wood in grinding contact with a portion of the length of said surface, means operatively associated with said sup port for moving said pulpwood support toward the sur face to hold the pulpwood in grinding contact, and linear drive means operatively associated with said support rela tively moving the support in a general axial direction parallel to the grinding surf-ace to progressively change the axial location of grinding contact between the pulp wood ‘and grinding surface whereby the pulpwood pro a relatively small pocket 78 is utilized, presenting to the 40 gressively engages areas of the grinding surface of chang ing diameter. changing grinding radius a relatively smaller contact area than has heretofore been employed with the result References Cited in the ?le of this patent that not only is the sharpening eriod prolonged, but the UNITED STATES PATENTS power requirements to maintain the optimum unit loading 87,139 Burghardt ____________ __ Feb. 23, 1869 or grinding pressure at the nip is markedly less than has rubbed, so that a minimum amount of ?nes are produced. it may be observed upon reference to FEGURE 1 that previously been the practice. It is apparent from the foregoing description that si multaneous movement of the grinder member and pulp wood sticlrs relative to one another can be accomplished in numerous ways utilizing various structures. The 50 ground pulp is of course collected in any convenient man ner, and thereafter subjected to conventional processing steps. The apparatus disclosed functions effectively on all known wood employed for mechanical pulping, and 491,971 492,425 571,019. 1,476,032 Schmidt _____________ __ Apr. 23, 1889 Eilers, Jr _____________ __ Apr. 30, 1889 Roberts _____________ __ Nov. 10, 1896 Aicher ________________ __ Dec. 4, 1923 20,141 41,073 Germany ____________ __ Nov. 22, 1882 Norway ______________ __ Mar. 9, 1925 FGREEGN PATENTS 49,672 ermany ____________ .._ Nov. 25, 1889 in 629,394 Germany _____________ __ May 6, 1936 substitution for generally ?at grinding suriaces lying 682,946 France ______________ __ Feb. 24, 1929 customary pre-treatrnent may be utilized as desired.