US 2964250 A
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Dec. 13, 1960 Filed July 15, 1954 A. J. A. ASPLUND GRINDING APPARATUS FOR FIBROUS MATERIALS Fig.1
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GRINDING APPARATUS FOR FIBROUS MATERIALS Filed July 15, 1954 5 Sheets-Sheet 4 Dec. 13, 1960 A. J. A. ASPLUND 2,954,250
GRINDING APPARATUS FOR FIBROUS MATERIALS Filed July 15, 1954 v 5 Sheets-Sheet 5 INVENTOR dme Jdn drZZr A'ITORN EY .kind composed of or containing fibres. described is of the type which includes a rotatable and United States Pate GRINDING APPARATUS Foii FIBROUS MATERIALS AmeJohan Arthur Asplund, Bromma, Sweden, assignor .40 Aktiebolaget Defibrator, Stockholm, Sweden, a corporation of Sweden FiledJuly 15, 1954, Ser. No. 443,637
Claims priority, application Sweden July 15, 1953 9 Claims. (Cl. 241-256) This invention relates to grinding apparatus for the breaking down of certain materials, preferably of the The apparatus .a non-rotatable or stationary grinding member, such as in the form of grinding discs and wherein the rotatable are already more or less completely drawn apart, for
the purpose of separating fibre bundles and effecting .disintegration of the fibres themselves. The fibrous material .is then utilized for the manufacture of paper, pasteboard,
fibre boards and similar products.
To obtain favorable results in the breaking down or disintegration of cellulose or of fibrous material already partly defibrated by steam treatment, for example, in grinding apparatus or so-called finishing-machines, it is of great importance that the working faces of the grinding discs be adjusted with such accuracy as to reduce the deviation from true parallelism thereof, measured circumferentially, to a minimum and most preferably to limit said deviation to one or a few hundredths of a millimetre. As the discs have a diameter frequently amounting to one meter or more it will be readily understood that this accuracy regarding the relative positions of the grinding discs places extraordinary demands on the preciseness of construction and adjustment of the finishing machine. The primary object of the invention is to provide a grinding apparatus satisfying all requirements in this respect.
The invention will be hereinafter described more detailed with reference to an embodiment illustrated by way of example in the accompanying drawings, features characteristic of the invention also being set out in this connection.
Fig. 1 is a side elevational view of a grinding apparatus constructed in accordance with the invention;
Fig. 2 is a cross section on line IIII of Fig. 1;
Figs. 3 and 4 when placed end-to-end, constitute a vertical longitudinal section through the apparatus;
Fig. 5 is a sectional view similar to Fig. 4 as to a substantial part of the mechanism shown in that figure but on .an enlarged scale;
Fig. 6 is a cross sectional view through the shaft and its supporting elements, the view being taken on the line 6-6 of Fig. 3, looking in the direction of the arrows, and Fig. 7 is a sectional viewtaken substantially on the line 7--7 of Fig. 5, looking in the direction of the arrows.
Referring to the drawings, 10 designates the frame ot" theapparatus carrying shaft 12 mounted in two bearings generally indicated by 14, 16. On its one end the shaft ,is connected by means of a coupling 18 with the shaft of a driving motor 20. On its opposite end the shaft 12 carries a grinding disc 22. The shaft 12 and the grinding disc 22 are adjustable in an axial direction relatively t'o' a stationary grinding disc 24. For this purpose a coupling sleeve 26 is secured to the shaft 12 and engages means of its ridges 28, axially extending grooves 30 provided in an external casing 32 enclosing the coupling 18 and connected with the motor shaft. 7
The bearing 14 located adjacent the coupling isintended to absorb the radial load and consists of a spherical double-row roller bearing having its inner ring splined onto the shaft 12 by means of a clamping sleeve 34. The outer ring 36 of the bearing is encased by an inner bearing housing 38 in the form of a sleeve and provided with a bearing cover 40 fixing the outer ring relatively to said inner housing 38. This latter is in turn disposed axially slidable in an outer bearing housing 42 secured to the frame 10 by means of lateral flanges 44 and bolts 44a (Fig. 6). The inner housing 33 is slidably operative against rails 42a provided on the inside lower surfaces of the housing 42. A shoe 46 engages the bearing housing 42 and by a number of pre-compressed springs 48 is kept pressed against the inner bearing housing 38 for the purpose of eliminating any play. The shoe 46 also locks the bearing housing 38 against any movement in a peripheral direction.
The bearing 16 disposed adjacent the grinding disc '22 has conical rollers 50 co-operating with a ring 52 carried .by the shaft and fixed thereon by a key 52a and with a non-rotative or stationary ring 54. The bearing 16 is capable of absorbing both axial and radial loads. An annular spacing member 58 is located between the inner ring 52 and a shoulder 56 provided on the shaft 12; The bearing 16 is kept under continuous axial .pressure by means of an axial thrust bearing 6% suitably of conical type. The inner ring 62 ofsaidbearing 64 is splined onto the shaft 12 by key 62a, and also on said shaft is an oilcentrifuging disc 64 positioned thereon by means of a stop nut 66. The outer. ring 68 of the bearing 60 is pressed through a precompressed conical cup spring and a sleeve 72 against the stationary ring 54 of the bearing 16. The initial axial pressure acting 'on said bearing corresponds to the pro-compression of the spring 70 which may amount to several tons and is at least equal to the axial power component acting on the bearing 16 and produced by the weight of the rotating parts, occurring unbalances inherent to said parts and so forth. In order to be capable of absorbing radial loads, the bearing 16 must at the same time be subjected also to an axial load which latter is insured by the device just described even when the apparatus is out of-operation. The sleeve 72 is enclosed within an inner bearing housing 73 and is keyed thereto by the key 72a so that the sleeve 72 is non-rotative relatively to the housing 73. The bearing ring 54 is disposed and which is axiallydisplaceable together with the shaft '12 in an outer bearing housing 75. Housing 53 is provided with lateral flanges "In by which it is secured, through the bolts 76a, to the frame 10. In order to eliminate the effect of play between the two bearing housings 73 and a sliding shoe 74 recessed into adjacent peripheries of the housings is disposed to exert a pressure on the bearing housing 73 by means of precompressed springs 76.
The outer housing 75 is suitably provided in its interior lower portion with two axially-extending rails 75a against which the bearing housing 73 is slidably operative.
The rotating grinding disc 22 is rigidly connected to a rotor '78 by means of bolts 80. Within the grinding disc 22, seen in the radial direction, there may be located a second grinding disc 82 rigidly securedto the rotor 78 by means ofbolts-84. The stationary grinding disc 24 is connected with a stationary member 88 by means of three circumferentially-spaced locking and adjusting devices 86. Each device 86 comprises a fixing bolt 87 engaging the grinding disc 24 with threads and passing with play through a sleeve 89 threaded into the member 88 and having for its object to adjust the position of the grinding disc 24 relative to the member 88. The adjusting sleeve 89 has a polygonal head 91 and is locked by means of a nut 93. The concentric location of the locking and adjusting members relatively to one another avoids bending moments likely to deform the grinding disc 24.
The member 88 carries within the grinding disc 24, seen in the radial direction, a second stationary grinding disc 90 rigidly connected with said member by means of bolts 92. The surfaces facing one another of the two grinding discs 22 and 24 are channeled in the known manner for the purpose of producing the desired disintegration of the material to be ground. The discs 82 and 90 may constitute supply members for the material introduced through a channel 94 and preferably also produce a preparatory disintegration of said material. The grinding discs are enclosed by a casing 96 divided in a horizontal plane and comprisIng two strong central parts 97 (Fig. 1) made integral with the member 88 and transmitting the grinding pressure from the grinding disc 24 to the frame 10 with which they are connected by means of bolts 99. Above and below the parts 97 there are hoods or covers 101 and 103 secured to said parts by means of bolts 105 and 107, respectively. Upon removal of one or the other or both of said covers 101, 103 the grinding members 22, 24 and 82, 90 are immediately accessible for replacement, adjustment or control. The cover 103 is open at its base in order to enable the ground material to be discharged.
The grinding disc 22 is kept under pressure acting in the direction toward the grinding disc 24 by means of a servo-motor generally indicated by 98 and comprising a casing 100 rigidly connected with the frame and a piston 102, both said casing and said piston concentrically and with play surrounding the shaft 12. The piston 102 has a central flange 104 axially displaceable within a chamber 106 (Fig. 3), the lateral walls 108 and 110 of which limit the path of free motion of the piston in the axial directions. Wall 108 is formed on a ring 108a fastened to the casing 100 by screws, one of which is shown at 100a in Figure 5, but omitted from Figure 3 for simplicity in illustration. The chamber 106 has at its both ends inlets and outlets 112, 114 for a compressive liquid, such as oil. The piston 102 is only, with a suitably adjusted small play, sealed against the surrounding casing 100. Liquid leaking out of the casing is removed through annular grooves 116, 118.
A sleeve 120 provided with external threads 12017 may be rigidly secured by the key 120a to the end of the servo-motor piston 102 facing the bearing 16. The thread has a pitch of an order of magnitude of millimetres. The sleeve 120 carries an annular member 122 threaded thereon and provided with an axially-extending groove 124 engaged by a pin 126. The sleeve 120 further carries a ring 130 threaded thereon and an annular plate 128 spaced axially from said ring 130. A number of circumferentially-spaced bolts 132 pass with play through the ring 130 but are threaded into the plate 128 and a member 134 forming a cover sealing the bearIng housing 73. The bolts compress springs 136 abutting against the ring 130 which results in eliminating the effect of a play between the threads connecting the members 102 and 134. The member 122 abuts a spherical face 138 against an annular member 140 provided in the cover 134 and held against rotative movement relatively to the cover 134 by the pin 140a. The total pressure exerted by the springs 136 is larger than the resistance of the parts connected with the shaft 12 when displaced to the left, viewed in the plane of the Figs. 3 and 4.
A worm wheel 144 is rigidly secured to the piston 102 of the servo-motor and co-operates with a worm 146 disposed on a transverse shaft 148. Said shaft 148 is preferably provided on each end with a hand wheel 150 the shaft being mounted in bearings such as 152, 154. By turning the shaft 148 the piston 102 of the servo-motor is caused to rotate. The housing 73, however, is nonrotatable due to the recessing of the sliding shoe 74 into its periphery, and therefore upon piston rotation member 122 will be displaced axially, and in its movement axially entrain the housing 73 and the sleeve 72, and therefore also axially move the shaft 12 and the grinding disc 22.
The axial movement of the grinding disc 22 relatively to the fixed casing is indicated by means of a measuring instrument 156 the scale of which is graduated for hundredths of millimetre, for example, and the movable measuring pointer 158 of which abuts against an inclined surface 160 provided on the cover 134. The measuring instrument 156 may be constructed adjustable so that its indicator will assume zero position when the two grinding discs 22, 24 are in contact with each other. The inclined surface 160 may have an inclination of 30 relatively to the centre line of the shaft 12. The pressure fluid such as oil is fed into the servo-motor 98 from a device generally denoted by 162 and comprising a motordriven pump, a multiple-way valve and conduits connecting said members with one another and with the servomotor and a sump. Two such conduits open into the chamber 106 of the servo-motor at 112 and 114, respectively. It is assumed to be suflicient to mention that said device 162 comprises an overflow valve 164 for control of the oil pressure and a button 166 for operation of the multiple-way valve.
The desired play or spacing between the grinding faces of the grinding discs 22 and 24 when the flange 104 of the piston of the servo-motor abuts against the surface 110, is adjusted by means of the hand wheel while reading off the measuring instrument 156. During such adjustment the piston 102 of the servo-motor is axially stationary, but due to its rotary movement it displaces the housing 134, 73, the bearing 16, the spacing member 58, the rotor 78 and the grinding disc 22 axially in one or the other direction without said elements participating in the rotary movement. In operation of the apparatus i.e. when material to be ground is supplied to the grinding discs through the channel 94, pressure oil is fed into the chamber 106 through the conduit 112. The oil pressure acts on the flange 104 and is transmitted through the parts 120, 122, 140, 134, 73, 16, 58, 78 and the grinding disc 22 to the material. It will be understood from this explanation that the shaft 12 does not participate in the power transmission from the pressure fluid to the grinding disc 22, if the shoulder 56 of said shaft located adjacent the rotor is disregarded. In the embodiment illustrated even the shaft packing 168 is disposed around that part of the shaft which is relieved from axial pressure. Due to the bearing devices described above and the radial initial tension-pressure acting thereupon, the axial displacements of the shaft 12 are performed without any appreciable disturbance of the centered position thereof which feature assists in attaining the primary object of the invention of creating and maintaining the required extremely small play between the active faces of the grinding discs in spite of the large diameter of said discs. If during the grinding operation material to be ground agglomerates or hard objects, such as small stones or scrap iron fragments happen to find their way between the active grinding faces, the rotating grinding disc 22 and the power transmitting members between said grinding disc and the piston 102 of the servo-motor are displaced to the left, viewed in the plane of the Figs. 3 and 4, the flange 104 thereby being caused to disengage the lateral stop surface 110. Said surface constitutes at the same time a stop determining the minimum free play of the disc 22 relatively to the disc 24. By connecting the connection 112 with the sump in the device 162 and instead thereof supplying pressure fluid to the connection 114 the piston 102 of the servo-motor is forced to displace itself to the left and then to entrain all members forming part of the power transmitting chain ending with the grinding disc 22.
Of course the invention is not limited to the embodiment shown but may be varied in the widest aspects within the scope of the basic idea thereof.
What is claimed is:
1. A grinding apparatus for disintegrating fibrous material comprising, a rotatable grinding disc, a stationary grinding disc opposed thereto, the rotatable disc being carried by a shaft and being axially displaceable to provide for spacing between the discs, a hydraulic servomotor for axial movement of the rotatable disc, said servo-motor including a rotatively-adjustable piston, axial pressure-producing means operative on the piston including elements located between the rotatable disc and said piston and arranged on rotative movement of the piston to transmit axial pressure and movement to the rotatable disc and thereby alter the spacing between the discs, said elements being non-rotative but axially movable so that the same do not participate in the rotative movements of the piston.
2. A grinding apparatus as claimed in claim 1, in which the piston carries an element on which threads are provided for co-operation with threads on one of the elements transmitting the axial pressures which threads are subjected to an initial axial pressure to eliminate disturbing influence of play between said threads.
3. A grinding apparatus as claimed in claim 1 in which the elements transmitting the axial pressures include an axial thrust bearing capable of taking up radial loads and subjected to an initial axial pressure.
4. A grinding apparatus as claimed in claim 1 in which the piston of the servo-motor has a central and radiallyprojecting flange entering a chamber adapted to be connected to a pressure source on one or the other side of said flange.
5. A grinding apparatus as claimed in claim 1 in which the movement of the piston of the servo-motor in a direction towards the stationary grinding disc is limited by means of a stop preferably located within the chamber.
6. A grinding apparatus as claimed in claim 1 in which the shaft is rotatably mounted in and radially supported by bearing devices axially displaceable together with the shaft relatively to a stationary frame and subjected to an initial radial pressure.
7. A grinding apparatus for treating fibrous material comprising, a rotatable grinding member and a stationary grinding member, both members being in the form of grinding discs, a shaft on which the rotatable grinding member is mounted, a said shaft and the grinding member thereon being axially displaceable to provide adjustment of the mutual spacing of said grinding members, a servo-motor adapted to produce a compressive pressure acting on the rotatable grinding member but not on the shaft therefor, said servo-motor including a stationary casing arranged around the shaft, a piston located within the casing and disposed concentrically around the shaft, means by which a rotative movement may be imparted to the piston independent of any rotative movement of the shaft, said shaft being freely rotative within the piston, and means fixed against rotation but axially movable, said means being disposed between the rotatable grinding member and the piston for axially urging the rotatable grinding member toward the fixed grinding member or permitting limited movement of the rotatable grinding member in a direction away from the stationary grinding member, which means is caused to urge the rotatable grinding member in a direction toward the fixed grinding member by rotative adjustment of the piston, which non-rotatable but axially movable means does not participate in rotative axial movement during such movement of the rotatable disc.
8. In a grinding apparatus for treating fibrous 'material, rotatable and stationary grinding discs, the rotatable grinding disc being supported by a shaft, said disc being axially displaceable by means of a fluid-actuated servomotor for the adjustment of the mutual spacing of the grinding discs and in order to provide for grinding pressure between the discs, the servo-motor including a piston capable of rotary movement having a concentric sleeve extending around the shaft, said sleeve providing for a pressure-fluid chamber between it and the outer surface of the piston, the piston being provided with a circumferential flange entering in said chamber, pressure transferring means arranged between the rotatable grinding disc and the servo-motor and arranged for movement axially of the shaft, bearings disposed between said means and the shaft, said pressure-transferring means acting to transfer the grinding pressure to the grinding discs.
9. In an apparatus as provided for in claim 8, characterized by the fact that means are provided to apply rotative movement to the piston to actuate the pressuretransferring means by such rotative but non-axial movement of the piston to thereby change the spacing between the two grinding discs without requiring rotative movement of either the rotatable grinding disc or the pressure-transferring means.
References Cited in the file of this patent UNITED STATES PATENTS 1,316,281 Dalton Sept. 16, 1919 1,937,788 Ross Dec. 5, 1933 2,008,892 Asplund July 23, 1935 2,646,728 Coghill et a1. July 28, 1953 FOREIGN PATENTS 512,978 Belgium Aug. 14, 1952 686,657 Great Britain Jan. 28, 1953