US 3049307 A
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Description (OCR text may contain errors)
Aug. 14, 1962 D. R. DALZELL, JR 3,04
REFINING DISCS WITH ENLARGED GROOVES Filed Oct. 22, 1959 2 Sheets-Sheet l INVEVTOR. fiauzd 1?. Faye/Z; J2
1962 D. R. DALZELL, JR 3,049,307
REFINING DISCS WITH ENLARGED GROOVES Filed Oct. 22, 1959 2 Sheets-Sheet 2 U v J g, INVENTOR.
Unite Filed Oct. 22, 1959, Ser. No. 848,147 4 Claims. (Cl. 241-255) This invention relates to improvements in the art of refining fibrous materials and the like, and more particularly to improved discs for use in refiners of the attrition mill type. A particular refiner of this type is disclosed and described in United States Letters Patent No. 2,690,098, issued on September 28, 1954, to Dwight E. Jones and, for convenience, the discs of the present invention will be described in connection with such apparatus.
In the refining of fibers and the like it is the usual practice to suspend the material to be reduced or defibered in a liquid, usually water, and then to pass the resulting suspension into refining apparatus. In disc refining, the suspension is passed between parallel, relatively revolving discs provided with closely spaced, cooperating working faces having blades or raised projections over which the suspension passes and which reduce the fibers by abrasion or cutting to the desired form.
It is the principal object of this present invention to provide improved discs for use in such refiners. It has been discovered that improved refining results from having a maximum number of blades on the more rapidly revolving disc. However a minimum spacing between the blades is required in order to distribute the pulp suspension evenly over the disc face. By means of the present invention, great improvement in the number of effective blades is obtained substantially enhancing the refining effect of the discs.
The improvement according to this invention comprises a more rapidly revolving or propelling disc having blades arranged in circumferential segments, the blades within each segment being arranged in clusters extending across the Working face of the segment, with the blades Within each cluster being separated by grooves and the clusters being separated by enlarged grooves substantially wider than the grooves within the clusters.
Preferably the grooves on the rotating discs are between one-fourth and three-fourths inches in depth, the narrow grooves are between about one-sixteenth and three-sixteenths inches in width, the enlarged grooves are between about one-fourth and three-fourths inches in width and are spaced between about one and three inches apart and the surface of the blades varies between about one-sixteenth and three-sixteenths inches in width. Also preferably, the other disc in each disc set is provided with grooves which are of the same width as the narrow grooves in the propelling discs.
For the purpose of illustration, a typical embodiment of the invention is shown in the accompanying drawings in which:
FIG. 1 is a vertical cross-section of a refining machine with the discs mounted in place;
FIG. 2 is an exploded axial layout of the four refining discs of FIG. 1 looking from inlet to discharge;
FIG. 3 is a plan view of a portion of disc 3;
'FIG. 4 is a section taken substantially on the line 4-4 of FIG. 3; and
FIG. 5 is a section taken substantially on the line 5-5 of FIG. 3.
The embodiment illustrated is shown in FIG. I mounted in the refining apparatus disclosed in United States Patent No. 2,690,098. FIG. 1 herein is substantially the refining end of the machine therein shown in FIG. 3 and the discs herein indicated by the numerals 1, 2, 3 and 4 are therein indicated by the numerals 102, 106, 104 and 100, respectively.
The fiber stock and the like, to be refined, generally consisting of fibers suspended in water and usually under pressure, is fed into an inlet 5 and conveyed thence to the center of the first set of two cooperating discs 1 and 2. One of said discs rotates relative to the other. While this relative rotation can be accomplished by rotating the discs in opposite directions or by rotating them at different speeds in the same direction and such are included in the terms as herein used; No. 1 disc as shown is -stationary, while No. 2 disc is rotated in the direction indicated by the arrow. The stock is propelled outwardly between discs 1 and 2 into the peripheral casing chamber 6 by the pressure of the fluid and by the action of a disc 2, hereinafter to be described. From the casing chamber 6 the stock passes between the cooperating refining discs 3 and 4, disc 4 being herein shown as stationary while disc 3 is mounted to and rotates with the same rotor 7 as disc 2. In flowing from periphery to center the stock again is propelled by fluid pressure and by the action of disc 3, hereinafter to be set forth. From the center 8 of disc 4 the refined stock passes to the discharge 9.
The adjacent working faces of discs 1 and 2 and of discs 3 and 4 are provided with blades 10 over which and between which the desired refining occurs. These blades are arranged in circumferential segments or section 11, the edges of which and extensions 12 thereof converging tangential to a circle 13 having the center of the disc as its center. Due to the rotation of the rotating discs 2 and 3, the fiber stock is propelled in a spiral path moving in the direction of rotation of said discs, spiralling outwardly between discs 1 and 2 and inwardly between discs 3 and 4. To materially enhance this movement of stock the blades of discs 2 and 3 are disposed to propel the stock in the desired direction, disc 2 having blades the segments of which are offset from radial such that the inner ends of the blades lead the outer ends in the direction of rotation while disc 3 has blades the sections of which are offset in the opposite direction, that is, such that outer ends of the blades lead inner ends in the direction of rotation. Since it is the rotating discs 2 and 3 which give both the radial and the circular components ofmovement to the stock, these discs are herein called propelling discs.
It is apparent that without a countering force, the fiber stock in the grooves of the rotating discs would merely move outwardly in the groove between the blades without being subjected to refining action. This countering force is supplied by the disposition of the cooperating blades of said other or stationary discs 1 and 4 which op erate to cause the fibers to move out of the grooves and across the blade where they are refined. For this purpose the blades or the stationary discs should be disposed substantially perpendicular to the path of thefiherstock as it moves spirally between the discs. This is accomplished by olfsetting the blade sections from radial in the same direction as the cooperating, rotating discs inthe same disc set; that is, disc 1 has sections offset such that inner ends of the section edges lead outer ends in the direction of rotation of disc 2 and disc 4 has section edges offset such that outer ends lead inner ends in the direction of rotation of disc 3. This disposition is obtained by offsetting the blade sections of discs 1 and 4 from to 10 in the indicated directions while the rotating blade sections are offset tangentially from 5 to 25. In other terms, referring to FIG. 2, angles ABC may vary from 0 to while angles DEF may vary from 5 to 25". Furthermore, the blades in the blade sections 11 of disc 2 are arranged parallel to the trailing edge of said sections while the blades of disc 1 are arranged parallel to the leading section edges in the direction of rotation of disc 2 and the blades of the blade sections 11 of disc 3 are arranged parallel to the leading edge of the sections while the blades of disc 4 are arranged parallel to the trailing section edges in the direction of rotation of disc 3. With the blades thus disposed on cooperating working faces of the discs, the blades of cooperating discs always intersect at an angle thus avoiding parallelism which would result in the loss of refining action. In addition, the noise level of the machine is substantially reduced.
In accordance with this invention it has been found that the best refining is obtained by having a maximum number of blade edges consistent with the proper movement of pulp acros the faces of the blades. This is provided on the propelling discs by so spacing the blades 10 as to provide a majority of narrow grooves and a plurality of spaced internal grooves 21 substantially enlarged in Width and extending across the working face of each segment. This groove arrangement provides blades arranged in clusters within each segment thereby providing a larger number of blades for improved refining, improved stock distribution between coacting discs, and pressure control.
Preferably, in discs of commercial sizes, the surface of the blades 10 should be between about one-sixteenth and three-sixteenths inches in width, the narrow grooves 20 should be between about one-sixteenth and threesixteenths inches in width, the enlarged grooves 21 should be between about one-fourth and three-fourths inches in width and spaced about one to three inches apart, the depth of all grooves being between about one-fourth and three-fourths inches. In a specific example having discs 42 inches in diameter, the blades 10 are three-sixteenths inches in width, all grooves are five-sixteenths in depth, the narrow grooves 20 are three-sixteenths inches in width, and the enlarged grooves 21 are three-eighths inches in width and spaced one and five-sixteenths inches apart. The spacing of the blades on the other or stationary discs '1 and 4 is not as important but desirably the grooves therein are the same size as the narrow grooves 20.
The operation of the cooperating disc faces is believed to be substantially as follows. The pulp stock enters the groove spaces between the disc under the force of the fluid pressure and the blade disposition above described. The stock is put into spiral motion by the rotation and blade disposition of the propelling discs 2 or 3. This motion is resisted by the blades of the stationary disc 1 or 4 respectively which resisting force causes the fibers to be forced out of the grooves not only by direct action but also by a pressure distribution set up in the grooves, and to be forced between and across the interacting and intersecting blade surfaces of the two coacting discs where refining by abrasion (heating) or cutting takes place. For refining the blades of a two-coacting disc should not intersect at an angle greater than about 50.
The number of blade sections 1'1 herein shown disposed circumferentially of the discs is 18. This number has been found to be a satisfactory compromise between the desire to have as many as possible to keep the angle of blade intersection between the rotating and the stationary discs as nearly constant as possible and ease of manufacture.
To facilitate entry of the fiber stock between discs 1 and 2 and to facilitate central discharge from discs 3 and 4, at least one recess space 15 is provided at the inner portion of each blade section. Entry of the fiber stock between discs 3 and 4 at the periphery thereof is materially aided by beveling inwardly the outer ends of certain blades at each blade section on each disc, herein illustrated with alternate blades beveled. These beveled edges providing entry passages are indicated at 18 (FIGS. 3 and 5). For the same reason, the smallest blade 22 on rotating disc 3 is eliminated in each blade segment 11. Except for the beveled edges 18 and blades 22, disc 2 is identical with disc 3.
While the normal tendency is to pump from center to periphery, no difficulty has been encountered in pumping from periphery to center in discs 3 and 4 due to the action disc 3 which must be rotating and due to the fluid pressure at the circumference which has increased in passing between discs 1 and 2. Units of this type have been constructed to give improved refining with a small pressure drop through the refiner.
As disclosed in the aforesaid patent, the spaces between the stationary and rotating discs are adjustable by selfcentering means which maintains the space between discs 1 and 2 substantially equal to the space between discs 3 and 4, with yielding means to permit the rotating discs to move off-center in response to expected pressure in one of the spaces, produced for example by passage of a solid object.
It should be understood that the foregoing description is for the purpose of illustration only and that this invention includes all modifications falling within the scope of the appended claims.
1. A propelling disc adapted for use in a refining machine having cooperating, relatively rotating discs having blades on their adjacent faces arranged in circumferential segments extending from the interior to the exterior of the working portion thereof, said propelling disc having blades within each segment arranged in clusters extending across the working faces of said segments, the surfaces of the blades of said disc being flat and defining a common plane, the blades within each cluster being separated by narrow grooves between about one-sixteenth and threesixteenths inches in width, the clusters being separated by enlarged grooves between about one-fourth and threefourths inches in width.
2. A propelling disc according to claim 1 further characterized in having grooves between about one-fourth and three-fourths inches in depth, and blade surfaces between about one-sixteenth and three-sixteenths inches in width, said enlarged grooves being uniformly spaced apart between about one inch to three inches.
3. For use in a pulp-refining machine of the disc type, a pair of coaxial refining discs one of which rotates relatively to the other so as to constitute a propelling disc, said discs having blades on their adjacent faces arranged in circumferential segments extending from the interior to the exterior of the working portions thereof, said propelling disc having the blades within each segment arranged in clusters extending across the working face of said segment, all of the blades of said propelling disc having flat surfaces defining a common plane, the blades within each cluster being separated by narrow grooves, the clusters being separated by enlarged grooves substantially wider than the grooves within said clusters, the other disc having blades with flat surfaces defining a common plane and having grooves all of which are substantially of the same width as the narrow grooves of said propelling disc.
4. Refining discs according to claim 3 wherein said propelling disc has grooves about five-sixteenths inches in depth, blade surfaces about three-sixteenths inches in width, narrow grooves about three-sixteenths inches in 5 width, and enlarged grooves about three-eighths inches in 104, width, said enlarged grooves being uniformly spaced about 261,099 one and five-sixteenth inches apart. 2,03 5,994 2,968,444 References Cited in the file of this patent 5 UNITED STATES PATENTS 145 676 20,083 Natcher Apr. 27, 1858 1 23 55 6 Bowman June 14, 1870 Lehmann July 11, 1882 Sutherland Mar. 31, 1936 Jones Jan. 17, 1961 FOREIGN PATENTS Germany Oct. 31, 1903 France May 26, 1884