US2378481A - Method and device for shredding materials - Google Patents

Description

June 19, 1945.

J. L. HUTCHINGS' METHODS AND DEVICES FOR SHREDDING MATERIALS 3 Sheets-Sheet 1 Original Filed Sept. 1, 1939 I v Q mmgzmmmxmwm M X z W a w, //////.VK w w June 19, 1945.

J. L. HUTCHINGS METHODS AND DEVICES 'FOR SHREDDING MATERIALS Original Filed Septl 1, 19:59 3 Sheets-Sheei 2 I June J. L. HUTCHINGS 2,378,481

METHODS AND DEVICES FOR SHREDDI NG MATERIALS Original Filed Sept. 1, 1939 3 Sheets-Sheet 3 iii Patented June 19, 1945 .-M'ETHOD; AN DJ DEVICE FOR SHREDDING MATERIALS iJosephLJHutchings, Newark, N. J., Brosites Machine Company, Inc., N; Y.,a'corp oration of New York September 1, 1939,.Serial No. 293,135, nowPatent No. 2,309,594, dated Janu- .Original application assignor to New York,

ary' 26, 1943. Divided and this applicationMay 25,1942; Seria].'l\To.'444,450

aclaims. (01-. 7c .101)

'IThis' inventionxrelates to shredding devices and more particularly tometho'ds' and apparatus for formingthe shredder saddleof Such devices.

This application. is adivision of myco-pen'ding application,lSerial"No." 293,135, I filed September l, "1939, which matured as'"U. S. Patent No."2",309,- f5'94,jgran ted"Januaryl26, '1943. "In thatgpatent; certain. novel shredding devices *aredescribed which are particularly adapted. for th'e"treatment f certain raw or intermediate materials. at certain stages in the production of viscose .for themanufacture of artificial silk or thelike. important element of 'thej'shre'dder described is asaddle member which cooperates .-with the :rotating blades of the shredder to.th0r- "ough'lydi'sintegrate orishredithe soda cellulose or similar'material, and it..is with this memberthat the 'presentdivisional application has to..do. The "configuration-10f theisaddle member by which cerpain-advantages .areattained, especially in-.con-

nection 'withithe'treatment ofthe cellulose'material described,;is covered by the above mentioned patent,"and it'is an object ofthe. invention in its present'aspectto ;provide novel processes and apparatus if or' making "these saddles. Although peculiarly; adapte'd to-the shredding of the matee "rials mentioned inthe. above cited paten-t, itwill beunderstoodthat "the saddles produced .by' the '"presentme'thods"and: apparatus can be usedin theshre'dding of any analogous or similarmate- 'ria'ls' and inconnectiontwith. any suitable type of moving blades or. shredder members.

In'thecase of shredder .devices now extant, the shredder'members' are either made offhardcast metal=with theserrationsor teethformed therein. 1 during-thecastingiprocess or, as in the case o1v one "knowndevice, the teeth are machined. in a relatively-soft metal plate which is. then bent or 'warpe'd into-the cylindrical shape. desired.

1 In the former and more conventional case, the .'dia'mond"shaped serrations are .cast directly .in

, th'e' c'urve'd portion of' thesaddles, 'adjacentto the blades. It-is'well-known'that the uniformitypf .clearance between *allpoints of the. serrations. on the saddles'an'd' the serrated edges of. the-rotating blades'has a'great'deal to do with successful and speedy reductionof 'thematerial' being shredded.

' 'Wherethe diamond shaped, or pyramidal teeth "or *serrations' are formed on the curved surfaces -by=a casting process, it hasbeen found that due to War-pageendshrinkage of the castings themselvesg'it ispractically impossible .to maintain all 'the'jpointspfthe pyramidscast in the curved "section accurately withthe cylindrical surface having the samecenterv or axis ofcurvature asthe anelement of said cylindrical surface.

center of rotation of the blades. It is,,therefore, impossible to maintainthenecessary clearance exactly uniform between. the rotating blade and the saddle surfaces as defined byjthepointspr a pices of -th'epyramids. Hence, itcan beseen that if the clearance betweenlthe paddle blades and the saddle at the'top 'of the'saddle curve would be setfor .010", it mightbe (0'60" 'at the bottom of the saddle curve, orthe blades may even touch the saddle at the bottom. Therefore, I

clearances larger than those desiredihave had to be accepted since molded iron castings icannotbe held to the tolerances required. Thereforaimachines of the .class'described above, withcast saddles'have had to be run longer than necessary than if the proper clearances could :have ;been obtained, to reduce'a batch of pulp'to the proper shredded consistency. I v

.The other expedientinvolvingthe bending or curving of a relatively thin malleableplateinto which the teethhave already been machined, is

subject to 'the'same inaccuracies dueto uneven shrinkage or warping," and a further disadvantage arises from the necessity of sealingoff or properly 1 packing the serrated insertable.plates with respect to their mountings in the container to .pre-

vent'leakage of material orcooling'water.

One of the "objects of the presentzinvention, therefore, isto'provide a..novel and improved method of manufacturing'shredderelements such as the saddles described. v

The invention in'its preferred embodiments, contemplates the provision 'ofra saddle which is preferably made of a'special hard iron casting having two eylindrically curved surfaces accurately machined thereonto correspond withlthe surface of rotation'of the'blades, allowing forthe proper-clearance. 'Intothesecurved surfaces are then out two series of parallel V-shaped grooves, the grooves of the respective series being atp to each other-and all'of the grooves being disposed at 45 to the vertical median plane which passes through the saddle surface and, which contains When cut tothe proper depth thereresults a group'of'staggered substantially diamond-shaped or pyramidal'teethor projections on eachcurve'd' surface,

allof the points of which lie in a substantially cylindrical vsurface the axis ofwhich coincides with the axis of the blade.assembliesporlpaddles.

The blades carried by the .paddles.may then be adjustedto any desired clearance and this clearance distance will be uniform at any .pointon. the

.saddle surface. Also, the edges of the-serrations producedv by, machining, will naturally be sharper material placed in the container I 0.

than those produced by casting the serrations in the curved surfaces. It has been proved in actual operation that these sharp edges tend to expedite the shredding of the material. It has also been found in actual tests that a saddle of-the above construction greatly reduces the time of shredding and, when employed in connection with blades as hereinafter described, efiects astill further reduction in the time required for shredding or disintegrating a batch of material.

Furthermore, by certain of my improved methods for forming the working surfaces of these saddles, the pyramidal teeth may be so cut that, while those which are on the median line of the surface are symmetrical, the apices of the others are oifset in a direction away from the median line of the surface and to a degree proportional to their distance from said line. Thus the teeth nearer the oncoming material are provided with more abrupt cutting edges than those adjacent the median line.

Other objects and features of novelty will be apparent from the following specification when read in connection with the accompanying drawings in which certain embodiments of my invention are illustrated by way of example.

In the drawings:

Figure 1 is a view in horizontal section of a shredding device having a saddle embodying the principles of the invention;

Figure 2 is a view in vertical transverse section taken on line 2-2 of Figure 1;

Figure 3 is a somewhat diagrammatic view in side elevation of one type of machine for cutting the teeth or serrations in the shredder saddle, a portion of the machine being shown in vertical section;

Figure 4 is a fragmentary plan view of one working face of the saddle as cut by the machine in Figure 3;

Figure 5 is a fragmentary view in transverse section of the same saddle, as taken on line 5-5 of Figure 4; I

Figure 6 is a diagrammatic view showing one of the symmetrical teeth adjacent the median plane of the working surface of the saddle;

Figure 7 is a similar diagrammatic view showing one of the teeth adjacent the margin of the working surface and having its apex displaced from the median plane;

Figure 8 is a diagram illustrating the approximate curvature of the path of the tool diagonally across the cylindrical working surface of the saddle as developed from the intersecting plane and cylinder;

Figure 9 is a somewhat diagrammatic View in elevation of another embodiment of saddle cutting machine; and

Figure 10 is a View of the same machine in transverse vertical section as taken on line III-I 0 of Figure 9.

One exemplary embodiment of the shredding machine, having a saddle or shredder element of the type described, is illustrated in Figures 1 and 2 of the drawings. In this device duplex blades are employed for cooperating with the saddle member for shredding and disintegrating the A cooling system may be employed if desired and such a system is fully described in my patent to which reference has been made.

The saddle H6 in this embodiment may be provided with a cooling duct I I6. The exact form of the serrations in this saddle and the method of forming them will be described hereinafter.

In the parallel, substantially cylindrical troughs H2 01 this machine there are disposed for rotation in opposite directions, the duplex blade or paddle members H5, these members being trunnioned in the end walls of the receptacle by means of the stub shafts I20 and I2I, the former being provided. with suitable driving means. Each of the paddle members I I5 comprises essentially two blade member I25 which extend from end to end of the paddles and comprise two spirally formed blade elements or sections which have twists of opposite hand, each of the sections being carried by the radial elements I26 which carry the trunnions or stub shafts I20 and IZI, and extending toward each other where they are joined together adjacent the mid-portion of the paddle by means of the curved connecting bars I21. These connecting bars or braces I21 are disposed adjacent the general periphery of the paddle elements so as to keep the axis of the paddle members clear of obstruction to the passage of the material being shredded.

The radial supporting elements or spokes I26 at the opposite ends of the paddles are disposed at right angles to each other and the blade I25 at each end of the device are positioned 180 apart. The twist of each blade section I25 is substantially 90 from one end of the device to the central portion. The ends of all four of the blade sections I25 which overlap to some extent at the mid-portion of the paddle member are disposed 90 apart as clearly shown in Figure 2 of the drawings.

The direction of twist of the interrupted spiral blade sections is such that the material being shredded is moved from the ends of the trough towards the central portion thereof, just as in the case of a previously described embodiment.

As previously pointed out, shredder saddles have heretofore been provided with teeth or serrations which have been cast therein durin the formation of the saddle member. To avoid the inaccuracies mentioned in connection with this type of saddle, the saddle I IS in the present embodiment is first cast to the general configuration required and then the cylindrical working surfaces are machined accurately to correspond with the cylindrical surface of revolution of the blades. The peak 82 of the saddle member is provided with a series of teeth or serrations, and intersecting grooves are accurately machined in the working surface 80 to provide pyramidal teeth.

As shown most clearly in Figures 4 and 5 of the drawings, the V-shaped grooves 85 and the grooves 85 are cut in the surface 80 in opposite directions so that they intersect at angles of The grooves are also preferably arranged so that they intersect the median plane of the working surface 80 (indicated at M) at angles of 45. These intersecting V-shaped grooves result in the formation of a multiplicity of pyramidal teeth 90, and in this particular embodiment, the teeth are so cut that those along the median plane M are symmetrical as indicated at R. In other words, the apices of these pyramids coincide with the radius of the curved surface 80 at this point. However, the teeth which are disposed at points at varying distances from the median plane have their apices olfset in a direction away from said median plane, and in amounts which. vary according to their distance from said plane. This effect is more clearly shown in the enlarged diagrammatic views in Figures 6 and 7 and is due to the method of cutting the teeth in the cylindrical surface by the employment of a rotary tool operating in a single plane which is disposed at a 45 a s'zsi'esi v 'I'65tto whi clr-the saddle dis-secured. The gibs angle with the median-plane Also, thera'dius of the c-utti-ng too1lisgreater than thQ 'TadlHS "of the cylindrical=surface 80 of the saddle. This Cutting tool -=radius -is adopted as that "which-will provide a-"circular arc which will' most-nearly approach the curvature ofthe {shallower or flatter arc-df an ellipse resulting 'fromthe intersectionv df'the plane of -the cutting toolwitli'the yli-ndrical surfacepf the-saddle. The 'developmentof "this arc is shown in 'Figure-"8 of the-"drawings'in which L represents the theoretical -cylinder'of fwhicn the'surface between thelines'c and-d represents' t-he actual' area -of the' workingsurface of "the saddle which, it willbe noted from Fig'ure 2 =df=the drawings, isless' than of the total 'cir- I mental angular extent, the arcs of the tangent obviously begreater than the radius'ofthecylindrical"saddlesurface. The actual length'of the tool arm may be obtained by measuring the chordal width of the cylindrical segments 0 d and the depth of the segment in the center thereof. Knowing the chordal length of c d and the angle of intersection of the plane P with the axis of the cylinder L, the chordal length of the tool path a: y may be determined. Then using the same depth of segment and applying it to the chordal length a: y, a circle may be erected having a radius which is equal tothelength of the tool arm. The are of this circle'which is subtended by the angular width of the saddle seg ment (approximately degrees) will be found to coincide with the fiat arc of the theoretical ellipse marking a line of intersection of the plane P and the cylinder L.

$66 serve Y to guide" the :member' I64 and suitable conventional? feeding-means. actuated by the-handle i I 61'- may be'provided for-feeding the'fixture 'l 65' alongthe-table I62 during the cutting of the se'veralgrooves. Ahead frame I10 supports'a driving motor Ill and'driving gearing I I2 operatively connected to the rotating tool shaft I15. A tail support for the shaft is provided at I16. Upon "theshaft "there is keyed a tool carrying wheel I TI .*uponwhich-asubstantially U-shaped'tool'holder v cutting-'- edge l-6I is disposed in-an opening in the -bott0m of the-holder I'I8and is=adjustable therein 'bymeansof the-screw I82. When set at proper point for taking a cut the tool is secured bymeans "ofthebolt I83. --As' shown inFigure 3 the saddle is held inthefixture I65 so that the working'sur- -;face"80 is in a substantially horizontal position but-disposed atan-angle of .withthe plane of-cut'of the tool. As each groove is cut thefixture I is 'moved'forwardly into the-position for "cutting the next one by means of the crank handle r61. 7

Another machine for'eifecting the'same typeof cut is'ShOWn in-Figures'Q and 10of the drawings.

"In this embodimentarock shaft'I 90 is supported At the median plane M as shown in Figure 5 of the drawings, the position of the axi of the cutting 'tool and that ofthe surface coincide and the teeth are therefore symmetrical as shown in Figure 6. At points further away from the median plane. however, the radius of thesurface 80 and that of the cutting tool necessarily diverge and theteeth assume the general form shown in Figure '7 with their apices s displaced from the radius 1. of the surface80. This effect provides a steeper or more abrupt cutting edge w on the teeth nearer to the edge of the working surface 80, which faces the oncoming material being swept across the surface 80 by the shredding blades. Of course, the pyramidal teeth will assume an opposite apparent distortion on the otherside of the median plane and this is utilized at times when the direction of rotation of the paddle members may be reversed.

In Figure 3 of the drawings there is illustrated somewhat diagrammatically one type of machine by means of which the teeth or serrations may be cut in the working surfaces of the saddle in order to attain the effect just described. A bed I60 is provided upon which a rotatable work supporting I table I62 is mounted. Suitable graduations I63 "in'the 'frame I9 I above the work'su'pport I92, the

' latter having similar arrangements to those'shown in Figure 3 for adjusting and advancing the work with respect to the cutting tool. The tool in this case is a milling cutter I 95 which has a stub shaft I96 rotatably mounted in the depending bracket arm I91 carried by the block I98 rigidly secured to the shaft I as by means of the pin I 99. Upon this block I98 there is mounted the driving metor v2 00, the shaft 20I of which carries the sprocket 202 which is operatively connected by means of the chain belt'203 with the sprocket 204 on the end of the stub shaft I 96 upon which the milling cutter is mounted. The block I98 carrying the cutter I is oscillated diagonally across the work by means of the link 205 which is pivotally connected as at 206 with the bracket arm I9! and at 207 with the crank gear 208. Thi is a worm gear which is driven by the worm 209 mounted on that this arrangement will produce the same type of teeth or serrations as the one described in connection with Figure 3.

It is understood that various changes and modifications may be made in the embodiments of the shredding machine and the various appurtenances thereof which have been illustrated and described herein, as well as in the methods and machines for preparing the saddle element for those devices, without departing from the scope of the invention as defined in the following claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. The method of forming a shredding saddle for a device of the class described, which comprises machining a concave cylindrical. surface of relatively small angular extent on a blank casting, and cutting in said surface two series of parallel V-shaped grooves which intersect at right angles and which make angles of 45 with a median plane which plane is perpendicular to said cylindrical surface and contains an element thereof, by rotating 2. cutting tool in successive parallel planes each disposed at a 45 angle with said median plane of said surface for cutting said grooves, and selecting as the radius of the cutting tool a length equal to the radius of a circle the curvature of which is substantially identical with that of the small minimum-curvature arc of the ellipse describing the angular intersection of the plane of movement of the tool with the complete cylinder of the saddle surface, the arc of the circle which coincides with said elliptical arc comprising the actual path of the tool along the relatively narrow working surface of the saddle.

2. The method of forming a shredder member of the class described which comprises the steps of providing a concavesubstantially cylindrical working surface of limited angular extent on a metal blank, and cutting in said surface two series of parallel substantially V-shaped grooves, the grooves of the respective series intersecting each other at the same angles, and each series intersecting any element ofsaid cylindrical surface at an angle which is equal to one-half of said first named angle, by rotating a cutting tool in successive planes each disposed at the same angle with any element of said cylindrical surface as said series of grooves, and selecting as the radius of rotation of the cutting tool a length equal to the radius of a circle the curvature of which is substantially identical with that of the small minimum-curvature arc of the ellipse describing the angular intersection of the plane of movement ofwthe tool with the complete cylinder of the saddle surface, the arc of the circle which coincides with said elliptical arc comprising the actual path of the tool along the relatively narrow working surface of the saddle.

3. The method of forming a shredding member of the class described, which comprises the steps of machining a concave substantially cylindrical surface of an angular extent of not more than 30 ,7 degrees on a blank casting, and then cutting in said surface two series of parallel V-shaped grooves which intersect each other at a predetermined angle, and each of which makes an angle with any element of said cylindrical surface which is equal to one-half of said first named angle, said cutting being effected by rotating a cutting tool in successive parallel planes each disposed at the same angle with an element of said cylindrical surface as said series of grooves, and selecting as theradius of rotation of the cutting tool a length equal to the radius of a circle the curvature of which is substantially identical with that of the small minimum-curvature arc of the ellipse describing the angular intersection of the plane of movement of the tool with the complete cylinder of the saddle surface, the arc of the circle which coincides with said elliptical arc comprising the actual path of the tool along the relatively narrow working surface of the saddle. v

JOSEPH L. HUTCI-IINGS.

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