US2309594A - Method and device for shredding materials - Google Patents

Description

Jan. 26, 1943. J. l.. HuTcHINGs 2,309,594v

/ METHOD AND DEVICE FOR SHREDDING MATERIALS Filed Sepb. 1, 1939 5 Sheets-Sheet l QJ@ MYMQ `Ian. 26, 1943. v J, HuTcHlNGs 2,309,594

METHOD AND DEVICE FOR SHREDDING MATERIALS Jan. l26, 1943. J. l.. HUTCHINGS METHOD AND DEVICE FOR SHREDDING MATERIALS Filed sept'. 1, 193s:

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Il I 'I Il Il 'III .Illlll f l www@ J. L. HUTCZHINGS v METHODl AND DEVICE FOR SHREDDING MATRIALS Jan. 26, 1943;

Filed seni. 1, 1959 5 sheets-sheet 4 glu/umm felb L. Hucbpqs 5ms@ M; M fm Jan. 26, 1943.

J. HuTcHlNGs 2,309,594

METHOD AND DEVICE FOR SHREDDING MATERIALS IIHHII 5 Sheets-Sheet 5 Filed Sept. 1, 1939 l' Munn nvliunml y vu CM1/oft,

l M/Mwmu Patented Jan.`26, 1943 I METHOD AND DEVICE FOR 'SHREDDING MATERIALS Joseph L. Hutchings, Newark, N. J., assignor to Brosites Machine Company, Inc., New N. Y., 4a corporation of New York York,

Application 'september 1, 1939, serial No. 293,135

(cl. 14s-122') 20 Claims.

appara-tus' for preparing certain operative por-` tions of thefshred'dingv machine.

By means of the present invention'a wide va-I riety of materials of a brous, felt-like or pulpy nature, whether of animal, vegetable, or mineral origin, may be disintegrated, but the invention is particularly applicable to the artificial fiber industry, in accomplishing an important -stepinv the manufacture of viscose. In this art, the manufacturing steps are briey as follows: First,

. the sheets of cellulose obtained from bleached wood pulp, cotton linters, or from both of' these sources, are mercerized by steeping in a caustic soda solution thus forming a compound known as soda cellulose. The, hen'licellulose is also recess of caustic soda is removed bymeans of a hydraulic press and the pressed sheets are shredded into tine crumbs. The comminuted soda ce1- lulose is aged for a suitable period of time and 'then treated with carbon bisulde, which' results .in the formation of orange-yellow crumbs ofone and must be carefully controlled to ensure 'a final product of uniform quality, and the sucacessful effecting of this reaction dependsto a great extent upon the thoroughness and' care with which the disintegration 'or shredding .of -tlie any other cause, or' which would not eEect a uniform mixing and shredding of the charge in the machine, would be entirely unsuitable in this art.

In the art of shredding 'as practiced today. there are two batch type machines'used. The rst, or older type has a trough adapted to accommodate two single sigma type blades mounted in parallel relationship and rotating adjacent the bottom of the trough and in directions toward each other. The bottom of the trough is soA shaped as to conform to the underside of these two blades with a running clearancefor moved by treatment with caustic soda.A The exvthe blades as they rotate. At the mid-point,

therefore, between the blades and parallel to them is formed'a peak or saddle produced'by the intersection of the twol curved bottom portions of the trough. This saddle is serrated and serves to shred the material in commotion with serrated shoes mounted along the outside diameterof the sigma blades. It can be readily seen, therefore, that each blade will make only one cutting or shredding action for each revolution ofthe blade against the cast serrated saddle.

In the second or newer type, there isa trough to accommodate two rotating blades mounted as described above. -These blades, however, diier from the above mentioned ones in that they have two cutting edges on each blade extending spirally across .the entire width of the trough and at 180 vto each other. 'It can be readily seen, therefore, that as the blades'rotate toward each other soda celllose is performed. -The size and uni-l formity of the resulting crumbs are important factors, as is also the maintenance of `a uniform 'moderate'temperatureduring the process. Thus it willvbe readily understood that any device or method which would .permit an excessive rise in temperature of the material 'through friction or shredding will be accomplished in conjunction with the cast serrated saddle as above mentioned at the rate ofltwo cutting or shredding actions for each revolution 'of the blade. 1t may, therefore, be expected -that if the blades are rotatedA in thetwo above mentioned machines at the same R. P. M., the shredding of the batch will be accomplished 'in one-half .the time in the second or newer type machine as compared with the irst or older type machine. This. however, is not the case, since in this later type of machine,

the cutting edges of the blade being one continuous helix fro'mfone side of the machine tov the other, the material'is pushed first against one side of the' machine and thenf back/against the other sidefwithout the proper mixing action being accomplished on the batch. This continuous blade Ialso tends to rotate the batch with it.

thereby absorbing power without accomplishing' the desired shredding of the batch.

Furthermore, in the two above mentioned machines, the saddles against which the blades operate to accomplishthis shredding are made of hard iron castings. The diamond-shaped serrations are cast directly in the curved portion of A duction of the material being shredded. Where the diamond-shaped, or pyramidal teeth or serrations are formed on the curved surfaces by a casting process, it has been found that due to Warpage and shrinkage of the castings themselves, it is practically impossible to'maintain all 'the points of the pyramids cast in the curved f section accurately with the cylindrical surface having the same center or axis of curvature as the center of rotation of theA blades. It is, therefore, impossibleto maintain the necessary clearance exactly uniform between the rotating blade and the saddle surfaces as defined by theV points or apices of the pyramids. Hence, it can be seen that if the clearance between the paddle blades and the saddle at the top of the saddlecurve would be set lfor .010", it might be .060" at the bottom of the saddle curve, or the blades may even touch the saddle at'the bottom. Therefore, clearances larger than those desired have had to be accepted since molded iron castings cannot be held to the tolerances required. Therefore, machines of the class described above, with cast 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.

In view of these premises, my invention has for one of its more particular objects the p rovision of a batch shredder in which is incorporated means for acting upon the material introduced therein at more frequent intervals without excessively increasing the speed of operation of the blade of the machine, improved means for causing the proper ow and circulation of the material being shredded, and cooling means passing through the machine and blade to ensure against any possibility of overheating.

A lrelated object is the provim'on a 'shredder of the class described, of a novel machined shredder saddle.

In one 'of its embodiments, the invention contemplates the provision of acontainer, adjacent the bottom of which are disposed a. pair of rotary blade assemblies of a generally cylindrical outline adapted to cooperate with the machined cut surface of a stationary saddle member to disintegrate the material. 'I'hese blade members or assemblies comprise` three interrupted or discontinuous substantially spiral blades, part of each of the blades being curved in one direction and the opposite part twistedv in the oppositeA direction, whereby the material is continuously fd away from the sides toward the intermediate portions of the blade at the approximate center 0f the container, and the proper mixing circulation set up whereby every particle of the material may be acted upon by the shredding blades. The provision of three blades'of this type also means` that lthere will beithree eireetive snredding operations of the device during a ,single rotation of theblade member', wherebyl this rotary member need not be driven a`t any higher speed to accomplish faster shredding; 'I'his will attain a two-fold advantage, namely., afaster shredding and-mixing.action, andthe material will not be tossed upwardly away from the zone `of operation of the blades as would bef the case Ythe saddle surface.

if a blade with a single cutting edge were speeded up to obtain the same number of cuts per minute as might be obtained on the above outlined blade.

In another embodiment the invention contemplates the provision of a container, adjacent the bottom of which are disposed a pair of rotary blade assemblies of a generally cylindrical out' line adapted to cooperate with the machined cut surface of a stationary saddle member to disintegrate the ma-teriai. These blade members or assemblies comprise two interrupted or discontinuous substantially spiral blades and attain to a slightlmsmaller degree the advantages above set forth in connection with the three blade assembly. f

In one embodiment, there may also be pro- `vided a-novel double-flow cooling tube passing through the mass of material being treated, and the blade members themselves as well as the stationary saddle member may also be cooled.

In 'lboth of the embodiments of the shredder illustrated and described in the present application, the shredder saddle is preferably made of a special hard iron casting having two cylindrically curved surfaces accurately machined thereon to correspond with the surface of rotation of the blades, allowing for the proper clearance. Into these curved surfaces are then cut two series of parallel V-shaped grooves, the grooves of the respective series being at 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 an element of said cylindrical surface. When cut to the proper depth there results a group of staggered substantially diamond-shaped or pyramidal teeth or projections on each curved surface, all of the points of which lie in a substantially cylindrical surface the axis of which coincides with blades carried by the paddles may then be adjusted to any desired clearance and this clearance distance will be uniform at any point on Also, the edges of the serrations produced by machining, will naturally be sharper 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'sad- -dle of the above construction greatly reduces the time of shredding and, when employed in connection with blades as hereinafter described, effects a still further reduction in thetime required for shredding or disintegrating a batch of material.

Furthermore, by my improved method and al1- paratus for forming the working surfaces of these saddles, the pyramidal teeth are so cut that, while those which-are on the median line of the surface are symmetrical, the apices of the others are offset in a direction away from Athe median Yline of the surface and to a degree proportional to their distance from said line. 'I'hus the teeth 'nearer'the oncoming material are provided with more abrupt cutting edges than those adjacent I the median line.

is illustrated by way of example.

In the drawings: Figure 1 is a view in horizontal cross-section of of Figure'll;

asoasei a batch shredder embodying the principles of the present invention;

Figure 2 is a vertical sectional view of the machine shown in Figure 1, taken substantially on line 2.-2 of that figure;

Figure 3 is a longitudinal cross-sectional view on an enlarged scale of .the shaft of one of the shredder blades showing the cooling fluid connection;

Figure 4 is a View in front elevation of the machine;

Figure 5 is a horizontal cross-sectional view of an embodiment of the invention employing a duplex blade;

Figure 6 is a fragmentary view in end elevation of the duplex blades;

Figure 'I is a fragmentary sectional view of one of the blades showing the manner of.attach ing the removable shoes having the serrated cutting edges formed thereon;

' Figure 8 is a somewhat diagrammatic view inl 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; i

Figure 9 is.a fragmentary plan view of on working face of the saddle ascut by the machine inFigure 8;

Figure 10 is a fragmentary view in transverse section of the same saddle, as taken on line I0--I0 of Figure 9;

Figure 10A is a diagrammatic view showing one of the symmetrical teeth adjacent the medianl plane of the workingsurface of the saddle;

Figure 10B is a similar diagrammatic view ,showing one of the teeth adjacent the margin Figure 13 is a view in elevation of another type of machine for cutting the saddle and which will yield a serrated surface as shown in Figure ;A

Figure 14 is a fragmentary vvieyir in transverse vertical section of the machine shown in Figure 13, and as taken on line I 4-I4 of that figure; and. i v` I Figure 15 is a fragmentary transverse vertical sectional view similar to Figure '10 but showing a diierent formation of t,eetli or serrations, suh as produced by the .machineshown in Figures 13 and 14.

One exemplary Yembndimen; of the shredding samev machine in of the blades to shred or disintegrate the material. This saddle is preferably removable and is secured in position between the two paddles as b y means of the bolt I1 as clearly shown in Figure 2. The detailed construction of these saddle members will be described hereinafter.

nach of the padcues or made assembnes is is provided with an axial shaft 20 which passes throughthe opposite end wallsv 2I and 22 of the container I0 as indicated at 23, and each comprises essentially three operative blade members 25, which are provided with roughened or serrated working surfaces 26 adapted to operate upon the material between these surfaces and the correspondingly machinedcut serrated surfaces of the saddle I5. These serrated working surfaces 26 are indicated somewhat diagrammatically in Figures 1 and 2 as formed directly on the paddle or blade members 25, but they may be, and preferably are, carried by separable and adjustably mounted shoes such as indicated in connection with the embodiments illustrated in Figures 5, 6, and 7 of the drawings.

The blades 25 are disposed peripherally of the blade members I5 at equal distances apart, namely 120, The blades are of a spiral configuration and are interrupted adajacent the V intermediate portion of the blade members I5 so 4that separate curved blade sections starting at each end of the blade members I5, twist spiral- 1y in opposite directions toward the central point of the members I5. In this Way the material is stirred by means of the blades as well as distintegrated and shredded by the coaction of the blades and the saddle I6, and the movement of the'material is effected from each end of the utube or receptacle'V III-toward the center, due ton the opposite curvature of the blade sections from each end of the machine. lThe degree of twist of the spiral blade members -may be varied to some extent, but in the example shown, Vthe blade .elements 25 are turned or twisted separately to overlap somewhat.

Numerous advantages accrue from the use of machine which is illustrated in Figures 1 to 4, in- Y clusive,of the .drawings cmprises a trough or receptacle I0 which is tiltably supported upon a basev lI. Thefbottom ofthe container III is blade member.

shaped to. provide two troghs I2 of parti-cylindrical shape conform/ing to the general cylindrical contour of the blade o'r paddle members which are designated generally by'v the reference numeral I5. Centrally of' 'ther-bottom, portion of.

the container III there isprovided a wedge-*shaped saddlemember -I5 of cast. 'metal having curved surfaces with teeth or serrations mac ed therein, which cooperate with the operative surfaces through an angle of approximately during onehalf of the lengths of the-blades or a full twist if the blades lwere continued from one end of the machine to the other, instead of being interrupted adjacent the mid-point. As clearlyl shown in Figure 4 of the drawings, theblade elements 25 may extend for al slight distance past the exact center of the members I5 so as this novel type of shredding blade .especially in connection with the disintegration of the cellulose products referred to labove.l For example7 the material is lconstantly being moved from the end walls 22 of the container toward the center thereof and thereis no tendency for the material to pack against these wallsor clog the paddle member'at-the ends thereof` The necessity for stui'ling boxes for th'e paddle shafts at the lend walls of the receptacle is thus obviated. Then again, the provision of three blades 'enables the? #effecting of three operations on the material against the saddle foreach revolution of the saddle permits accurate clearances between the .blade andsaddle v.at all points." Thus 'the proper` shreddingof the batch, can be completed in much less time than Withthe use of a' single v lblade or a' double continuous blade operating against a saddle the serrations of whichare cast therein. Also, .inL prior devices having continuous blades extending from end to end of the device, the mixing action cannot be accomplished In addition, the machine cut.`

. to the proper extent. Attempts have been made to attain this same purpose by'` reversing the action of the machine for periods of time, but it has been found that the blades in those devices do not shred the material efficiently when run in the opposite direction. 4

As a result of the provision of this triplex in terrupted blade, the apparatus may be operated somewhat more slowly than thesingle or double continuous blade machines and thus the material being shredded is kept well down within the zone of operation of the blades and not continuously tossed upwardly within the container will be accomplished by the blades provided inV accordance with the present invention, and they may be rotated at a somewhat lower speed, it may be necessary to provide additional' cooling means for extracting any excess heat from the mass of material which would be generated by the shredding action. Therefore, in accordance with the present invention there has been provided certain further means for dissipating this heat.

The shafts of the blade members |5 may be made hollow, being provided with the central conduit or chamber 28. One end of the shaft 20 is provided with an extension 30 which is provided lwith a flange 3| bolted as at 32 to the end of the shaft. This member forms the outer member of a swivel joint for the application of cooling liquid fittings to the rotary shaft, and for this purpose is provided with a flange 33 at the opposite large end thereof to which is fastened a perforated retaining plate 34 which ts around a shoulder on the fitting 35 and serves to retain the latter in place. Suitable packing material 36 is provided between the portion 31 of the fitting 35 and the wall of the member 3U for preventing leakage at this rotary swivel connection. Threaded upon the outer attenuated portion 38 of the stationary fitting 35 is the inlet and outlet fitting 40 which is provided with threaded openings 4| and 42 for the attachment of piping or flexible conduits for the cooling fluid.

Centrally of the fitting 40 there is a partition 44 which is provided with a threaded opening adapted to receive one end of the inner pipe or conduit 45 which extends from this point concentrically of the shaft 20 to the opposite end of the latter where it is received within the reduced recessl 46.V Sumcient clearance is provided between the inner conduit 45 and the inner walls of the fittings 40, 35, and 3|) and the walls of the opening 28 in the shaft 20 to providea return passageway for the cooling material. One or more openings 48 is provided in the con duit 45 adjacent the inner end thereof so that the fluid can iiow from the conduit 45Y to the 'annular conduit 28 or vice versa.

Thus there has been provided cooling means for the blades themselves, but `additional means may also be incorporated in the device for dissipating anyexcess heat from th'e material itself within the receptacle I0. This means is disposed through the central portion of the container above the shredding zone. and adjacent the portion of the machine where the material is forced upwardly from the zone of action of the blades thereon and constituting the so-called hot spot" of the batch. The position of this cooling arrangement is indicated very clearly in" Figures 2 and 4 of the drawings where the cooling means is indicated generally by the reference numeral 50. This means comprises a preferably peripherally corrugated outer conduit or casing 5| and a straight inner tube 52 passlng axially through the outer conduit. A n inlet and outlet tting 53 'is provided at one end of the device50 and is provided with the nipples 54 and 55 communicating respectively with the inner and outer tubes 52 and 5|. Suitable interconnecting' means between the inner and outer tubes are provided'at the opposite end of the structure, and may be similar to the corresponding means comprising the opening 48 at the right-hand end of the shaft 20 as shown in Figure 3.

'I'he two cooling means which have been described will adequately dissipate any extra heat which might be developed'during the shredding operation due to the faster shredding accompplished with this new type of shredder blade and 30 machined saddle.

The projecting ends of the blade shafts 20 may be mounted in any suitable form of supporting bearings and are adapted to be driven from any suitable source of power, preferably through 35 gearing which will serve to rotate the respective blade assemblies at different speeds. An arrangement which may be considered as exemplary is indicated diagrammatically in Figure 1 in which the intermeshing gears 60 and 6| are carried on the shafts 2|] and a driving gear 62 is employed to rotate them. No stuffing boxes for the shafts 20 are required on'account of the tendency of the novel paddle arrangements to continually move the material away from the ends of the troughs and toward the mid-portions thereof.

The container I0 together with its associated gearing is supported as at 63. upon the vertically extending `portion ||'V of the base for tilting movement in order to dump the shredded material after the batch has been sufliciently disintegrated.

The container I0 is provided with a cover 65 whichis provided with hinge lugs 66 rigidly secured to the pintle shaft 61 which is mounted for rotation in the lugs 65 formed on the container |0.` l

Suitable' latching means are provided for retaining the cover 65 in positionupon the container and the means shown includes a member |50 pivoted to an upstanding ear |5| carried 'by the cover 65 and through which the latch element 52 is adapted to reciprocate. The latch member |52 is provided with a hooked end |53 which is adapted to be clamped against the lip or flange |54 formed on the container I0. An

`vactuating handle |55 is provided which is pivoted to the latch member |52 as at |56 and is provided with a cam-shaped end |51 adapted t'o press against the upper end of the pivoted portion |50 in ,order to draw the latch |52 upwardly and clamp the hook portion |53 against the flange |54.

In Figures 5 and 6 of the drawings there Ais illustrated another embodiment of the invention, in which duplex blade vmembers are employed and in which a somewhat dierent cooling system is used. The longer sides and the bottom of the troughed container l are provided with systems of piping ||0 which forms a cooling jacket. Thesesurfaces of the receptacle are divided into four areas to which separate systems of. piping are applied. The area designated a is provided with a cooling system comprising a series of horizontal pipes having an outlet connection 'I0 and an inlet connection 1| adjacent the central portion of the bottom of the container. Similarly, the area designated b is cooled by a system of piping having an outlet connection 12 and an inlet connection 13 disposed in symmetrical positions with respect to the corresponding elements of the section a. The flow of cooling uid through these coils may be controlled in any suitable way, vsuch as for example by means of the valves 'l0' and 12 shown in the outlet connections in the drawings. The areas c and d at the other end of the receptacle are indicated in Figure and are provided with similarly positioned inlet and' out let arrangements (not shown). Thus it will be `seen that the material being shredded may be maintained at the desired temperature through a very readily and flexibly controlled cooling jacket system. Of course, other cooling means maybe provided in this embodiment, for example, as illustrated in Figure 4 in connection with the first form of shredder shown.

The saddle I|6 in this embodiment is provided with a cooling duct ||6 similar to the one shown inl connection with the first embodiment. 'Ihe exact form of the serratiohs in this saddle and the method of forming them will be described hereinafter.

In the parallel, substantially cyhndrical troughs ||2 of this machine there are disposed for Vrotation in opposite directions, the duplex blade or paddle members ||5, these members being trunnioned in the end walls of the receptacle by means of the stub shafts |20 and I2|, the former being provided with gears 60, 6|, and 62 in' all respects similar to the corresponding driving elements of the first embodiment. Each of the paddle members ||5 comprises essentially two blade members |25 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 |26 which carry the trunnions or stub shafts |20 and |2I,

and extending toward each other where they` are joined together `:adjacent the mid-portion. of the paddle by means of the curved connecting bars |2'|. These connecting bars or braces |21 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 |26 at the opposite ends of the paddles are disposed at right angles 4to each other and the blades |25 at each end of the device are positioned 180 material against the corresponding serrations on the saddle ||6. One means of adjustably securing the shoe to the blade |25 is shown in Figure. 6. A bolt |33 passes through both the blade section |25 and the detachable `shoe |30. The bolt is provided with a head |34 and a nut |35 by means vof which it may be tightened against the shoe |30 in order to hold it in adjusted position. A dowel |31 prevents the head of the bolt from rotating. The bolt |33 passes through a slot |36 in the shoe |30 and the shoe may thus be adjusted inwardly or outwardly to provide the desired clearance between the serrated teeth |3| and the saddle.

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 4previously pointed out, shredder saddles have heretofore been provided with teeth or serrations which have been cast therein during the formation of the saddle member. To avoid the inaccuracies mentioned in connection with this type of saddle, the saddles |6 and IIS in the present embodiments are rst cast to the general configuration required and then the cylindrical working surfaces 80 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 surfaces 80 to provide pyramidal teeth.

As shown most clearly in Figures 9 and 10 of the drawings, the V-shaped grooves B5 and the grooves 86 are cut in the surface 30 in opposite directions so that they intersect at angles of 90. The grooves are also preferably arranged so that they intersect the median plane of the working surface 00 (indicated at M) at angles of 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 offset 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 10A and 10B and is due to the method `of cutting the teeth in the cylindrical surface by the employment of a rotary tool operating in surface of the saddle.

a single plane which is disposed at a 45 angle with the median plane M. Also, theradius of the cutting tool is greater than the radius of. the cylindrical surface of the saddle.V This cutting tool radius is adopted as that which will provide a circular arc which will most nearlyI approach the curvature of the shallower or flatter arc of an ellipse resulting from the intersection of the plane of the cutting tool with the cylindrical surface of the saddle. The development of this arc is shown in Figure 10C of the drawings in which L represents the theoretical cylinder of which the surface between the lines c and d represents the actual area of the working The plane P is the plane of rotation of the cutting tool and intersects the cylinder L to form an ellipse E. The arc of the ellipse between the points a: and y indicatesv the diagonal path of the cutting-tool along the surface of the saddle and for practical purposes this arc may be considered a circular arc and the radius thereof is adopted as the length of the arm of the cutting tool. This length will obviously be greater than the radius of the cylindrical saddle surface.

At the median plane M as shown in Figure of the drawings, the radius of the cutting tool and that of the surface 80 coincide and the teeth are therefore symmetrical as shown in Figure 10A. At points further away from the median plane, however, the radius of the surface 80 and that of the cutting tool necessarily diverge and the teeth assume the general form shown in Figure 10B with their apices s displaced from the radius t of the surface 80. 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. 0f course, the pyramidal teeth will assume an opposite distortion on the other side of the median plane and this is utilized at times when the direction of rotation of the paddle members may be reversed. It will also be readily apparent that the teeth on the side of the median plane more remote from the oncoming material will be substantially self clearing, the material passing over these teeth along the edges having the less abrupt slope, thus preventing clogging of the saddle and backing up of the material. This, of course, makes for a more eilicient action of the cutting and shredding teeth on the side of the working surface which is nearer the oncoming material.

In Figure 8 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 |60 is provided upon which a rotatable work supporting table |62 is mounted. Suitable graduations |63 are provided for determining accurately the angular adjustment of the table |62 with relation tothe bed |60. Upon the top of the table |62 there is disposed a slide |64 which supports the fixture |65 to which the saddle I6, ||6 is secured. The gibs |66 serve to guide the member |64 and suitable conventional feeding means.

actuated by the handle |61 may be provided for feeding the fixture |65 along the table |62 during the cutting of the several grooves. A head frame |10 supports a driving motor |1| and driving gearing |12 operatively connected to the rotatlng tool shaft |15. A' tail support for the shaft is provided at |16. Upon the shaft there is keyed a tool carrying Wheel |11 -upon which a substantially U-shaped tool holder |18 is secured. A tool |80 having -a V-shaped cutting edge |8| is disposed in an opening in the bottom of the holder |18 and is adjustable therein by means of the screw |82. When set at proper point for taking a cut the tool is secured by means of the bolt |83. As shown in Figure 8 the saddle is held on the fixture |65 so that the working surface 80 is in a substantially horizontal position but disposed at an angle of 45 with the plane of cut of the tool.V As each groove is cut the fixture |65 is moved forwardly into the position for cutting the next one by means oi" the crank handle |61.

Another machine for effecting the same type of cut is shown in Figures 11 and 12A oi the drawshredding machine and thel various appurteings. In this embodiment arock shaft |90 is supported in the frame |9| above the work support |92, the latter having similar arrangements to those shown in Figure 8 for adjusting and advancing the work with respect to the cutting tool. The tool in this case is a milling cutter |95 which has a stub shaft |96 rotatably mounted in the depending bracket arm |91 carried by the block |98 rigidly secured to the shaft |90 as by means of the pin |99. Upon this block |98 there is mounted thedriving motor 200, the shaft 20| of winch 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 |96 upon which the milling cutter is mounted. 'I'he block |98 carrying the cutter |95 is oscillated diagonally across the work by means of the link 205 which is pivotally, connected as at 206 with the bracket arm |91 and at 201 with the crank gear 208. This is a worm gear which is driven by the worm 209 mounted on the shaft 2|0 of the motor 2| 2. It will be obvious that this arrangement will produce the same type of teeth or serrations as the one described in connection with Figure 8. y

In Figuresv 13 and 14-of the drawings there is illustrated a machine for cutting symmetrical teeth throughout the area of the working surface of the saddle. Such a saddle is shown in Figure 15 of the drawings at 2|6, the working surface being indicated at and the symmetrically formed teeth being designated -by the reference numeral 90. This effect is attained by the use of a cutting tool having a substantially spiral or- .bit and an axis substantially equal to that of the curved working surfacev 80'. In this device the bed 220 of the machine supports a work carrier 22| which may be fed longitudinally of the yhed 220 by means of the feed screw 222 actuated by the crank handle 223. The carrier or fixture- 22| is provided with beveled edges which are slid- 4ably received Within the gibs 224 carried upon the bed 220. A supplemental inverted channel shaped xture 225 is employed for supporting the saddle 2|6 in an upright position. The tool shaft 230 is disposed somewhat to one side of the saddle 2|6 and is mounted inthe head frame 23| and ln the tail .fr-ame 232 for both rotary and reciprocating movement so as to guide the tool 235 in a substantially spiral path in order to cut the diagonal groove in the Working surface 80' of the saddle. The tool 235 may be fed and adjusted by the screw 236 and heldl in set position by the bolt 231. A driving motor 240 is mounted upon the head frame 23| of the machine and by means of the pinion 24| drives the gear 242 which is splined upon the tool shaft 230. The shaft 230 is`provided with an extension 230' which carries a cam member 245 provided with a groove 246 which receives. the roller 241 carried by the pin 248 secured to the head frame 23| as at249. The groove 2,46 is of a spiral configuration corresponding to the desired conbined longitudinal and rotary movement of the shaft 230 to effect the proper cut by the tool 235. By means of this apparatus, the cast metal sad.

' dles may be accurately machined to provide symmetrical teeth or serrations on the working surfaces.

It is understood that' various changes and modications may be made in the embodiments of the narices thereof which have been illustrated and described herein, aswell as in the machines for preparing thesaddle element for those devices,

4 2,309,594 Y without departing from the scope of the inven- 1. For use m a shreddingV and mixing device;

of the character described, a rotary paddle mein-l ber comprising a plurality 'of spiral blade sections rigidly connected together and supported for rotation within said device, certain of said sections being spaced .at equal intervals peripherallyof said member adjacent each end thereof the center of said paddle members that the material being shredded 'will be made to flow from both ends of said receptacle toward the mid-portion thereof, and means for rotating said paddle members.

6. A shredding and mixing device of the class described comprising, in combination, a receptacle having a pair of parallel troughs Athereinof partially cylindrical contour, a substantially V- shaped shredding saddle disposed between said troughs and provided with machine cut serrations in its outer' surfaces, a pair of rotary padof 4and extending from the respective ends of the member toward the mid-point, the end portions of the blade sections which are adjacent said mid-point being offset peripherally from each other, and shredding means on said blade sections.

2. A shredding and mixing device of the class described comprising, in combination, a receptacle, a shredding blade member rotatably disposed within said receptacle, lsaid blade member comprising a plurality of peripherally spaced spiral blades, each blade having shredding members thereon and being interrupted adjacent the mid-,portion of said member, and of the blade v sections thus formed those adjacent one end of the member being curved in opposite hand from those adjacent thebther end of said member, whereby the material being shredded may be moved in one directionat one side of the approximate mid-portion and in the opposite direction upon the other side thereof.

3.r A shredding and mixing device as set forth in claim 2, in which each curved blade section has a twist of approximately 90 from the end of said blade member to approximately the midpoint thereof.

4. A shredding and mixing device of the class described comprising, in combination, a receptacle having a pair of troughs therein which are of a curved contour and which merge to form a ridge having a surface (with a multiplicity of serrations formed thereon, a pair of rotary paddle members one disposed within each of said troughs and spaced from said .ridge surfaces with a uniform running clearance, each of said paddle members comprising three spiral blades spaced apart peripherally of the paddle member at equal intervals, each blade being provided with a roughened working edge adapted in opdle members each disposed Within one of said troughs and having serrated spirally formed blades adapted to rotate with aiuniform small running clearance adjacent the serrated saddle surfaces to shred and disintegrate the material between them, the blades being twisted in opposite directions upon each side of the mid-points and of a hand which will cause the material being operated upon to ilow from the ends of said receptacle toward the center thereof. 7. In a shredding and mixing device of the character described,'a rotary blade member comprisingshaft portions adjacent the ends of said 4member, six spiral blade sections carriedfby4 said shaft portions, three of -said sections being spaced at equal intervals of 120 peripherally of said member adjacent each 'end thereof and extending from the respective ends of the member toward the mid-point, the end portions of the vblade sections which are adjacent said midpoint also being onset peripherally from each other, and shredding means on said blade sections.

8. In a shredding and mixing device of the character described, a rotary vpaddle member comprising four spiral blade sections rigidly connected together and supported for rotation within said device, twovof said sections being spaced at equal intervals peripherally of said member adjacent each end thereof and extending from the respective ends of the member toward the mid-point, the end portions of the blade seceration to cooperate with said serrated ridge to disintegratethe material between them, the twist of said blades being of such opposite hand on either side of the center of said paddle members that the material being shredded will be made to iiow from both ends of said receptacle toward the mid-portion thereof, and means for rotating said paddle members.

5. A shredding and mixing device of the class described comprising, in combination, a receptacle having a pair of troughs therein which are of a curved contour and which merge to form tionswhich are adjacent said mid-point .being offset peripherally from each other, and shredding means on said blade sections.

9. For use in a shredding and mixing device of the character described, a rotary paddle member comprising a plurality of discontinuous interrupted, generally spiral blades extending from end to end of the paddle member and connected rigidly together at their ends only, the means of connection being a pair of trunnion members' for rotatably mounting the paddleV member in the device, each blade comprising a spiral section extending toward the center of -the member from each end thereof, said sections a ridge having a. surface with a multiplicity of serrations formed thereon, a pair of rotary paddle members one disposed within each of said troughs and spaced from said ridge surfaces with a uniform running clearance, each of said paddle members comprising two spiral blades spaced apart peripherallyof the paddle member at equalv being peripherally oiset from each other and having their inner ends connected by a curved member which follows the general peripheral contour of the paddle member, whereby the' axial center of the paddle member is clear of obstructions to the movement of material.

10. A shredding and mixing device comprising a lreceptacle having `a shredding and mixingv paddle member disposed for rot-ation in the lower portion thereof only, said blade member including a hollow shaft element having connections for the supply and exhaustof cooling/huid, a

cooling member passing through the portion of said receptacle abovel the paddle member where the bulk of the 'material not actually being shredded'at the moment tends `to accumulate,

and means for supplying cooling fluid thereto and exhausting it therefrom.

11. In a disintegrating or shredding device for operating upon cellulosic material for use in the manufacture of artificial libres, in combination, a trough-like receptacle, a roughened portion in the lower part of said receptacle, a rotary bladed shredding member extending adjacent said portion and from end to end of the receptacle for forcing the material against said portion to shred it, said shredding .member being so constructed and arranged as to cause the material in the lower part of the receptacle to flow from the ends thereof toward the mid-portion.

12. For use in a shredding device of the class described, a shredding element formed of a cast metal blank having a concave, generally cylindrical, curved working surface, multiple series fil of intersecting V-shaped grooves machined in said surface, the grooves forming a multiplicity of pyramidal teeth, the apices of the teeth nearer the respective side edges of said element being offset toward said edges, the teeth along the center line of said element being symmetrical, the amount of offset of said apices being proportional to the distance of the teeth from said center line.

13. For use in a shredding device of the class described, a stationary shredding element having a roughened working surface across which the material to be shredded is adapted to be moved by means of a paddle member or the like, a plurality of series of V-shapedl grooves cut in said surface to form a multiplicity of quadrilateral, pyramidal teeth therein, grooves being disposed at an angle with the general direction of movement of said material, the teeth along the center line of said surface being symmetrically formed but the teeth spaced from said center line and toward the oncoming material having their apices offset outwardly, whereby a more abruptly inclined edge of the teeth is presented to the material.

14. In a distintegrating or shredding device for operating upon cellulosic material for use in the manufacture of artificial fibres, in combination, a trough-like receptacle, a roughened portion in they lower part of said receptacle, a rotary bladed shredding member extending adjacent said portion 'and from end to end of the receptacle for forcing the material against said portion to shred it, said shredding member also comprising means for causing the material in the lower part of the receptacle to ow from the ends thereof toward the mid-portion, the material 'at said mid-portion moving upwardly and then being displaced laterally toward both ends of the upper portion of said receptacle, a stationary tubular conduit traversing1 the upper portion of said receptacle from end to end thereof and penetrating the body of material tending to accumulate at the center of said4 upper portion before it is displaced 1toward the ends of the receptacle, and means for circulating a cooling uid through said conduit.

15. For use in a shredding device in the class described, a shredding member formed of a cast metal blank having a concave, generally cylindrical curved working surface, a multiple series of intersecting v-shaped grooves machined in said surface. said grooves forming a plurality of rows of pyramidal teeth extending lengthwise of the cylindrical surface, the teeth in a row along one element of said cylindrical member being symmetrical. the apices o f the teeth in the the other rows being offset away fromsaid element of the cylinder, the amount of oiset of the apices of the teeth in the several rows being proportional to the distance of said other rows from said element.

16. For use in a shredding and mixing device of the character described, a rotary paddle member comprising four spiral blade sections rigidly connected `in pairs at opposite ends of the member to stub shafts or trunnions for rotation within said device, the blade sections of each pair being spaced apart 180 degrees peripherally of the member adjacent the trunnioned ends thereof, said blade sections all extending from the respective ends of the paddle member toward the mid-point. the end portions of the blade sections which are adjacent said mid-point being offset peripherally from each other, and means for connecting adjacent ends of salid blade sections at the mid-point of the paddle member, said means being so constructed and arranged that the axis of the paddle member will be clear of obstructions to movement of material substantially .throughout its length, the twist of the blade sections on one side of the mid-point of said paddle member being oppositeA to that of the sections on the other side, whereby the material being shredded may be'moved in one direction at one side of the receptacle, and in the opposite direction at the other side thereof.

17. For use in a shredding and mixing device of the character described, a rotary paddle member comprising a plurality of spiral blade sections rigidly connected in pairs at opposite ends of the member to stub shafts or'trunnions for rotation within said device, the blade sections of each pair being spaced apart at equal intervals peripherally of the member adjacent the trunnioned ends thereof, said blade sections all extending from the respective ends of the paddle member toward the mid-point, the end portions of the blade sections which are adjacent said mid-point being o'set peripherally from each other, and means for connecting adjacent ends of said blade sections at the mid-point of the paddle member, said means being so constructed and arranged that the axis of the paddle member will be clear of obstructions to movement of material substantially throughout its length, the twist of the blade sections on one side of the mid-point of said paddle member being opposite to that of the sections o'n the other side, whereby the material being shredded may be moved in one direction at one side of the receptacle, and in the opposite direction at the other Aside thereof.

18'. The method of disintegrating cellulosic material for use in the manufacture of artificial Vlibres which comprises continually shredding a batch of the material in a receptacle by forcing the same against a roughened lower portion of the receptacle by suitable stirring means, and at the same time causing a continuous movement of streams of the material from the ends of the said lower portion of the receptacle toward and somewhat beyond the mid-point thereof, Whereby said streams moving toward saidmid-point from the respective ends of the receptacle yoverlap to some-extent at that point before intermirrgling. r

19. The method of disintegrating cellulosic material for use in the manufacture-of artificial bres which comprises causing a. plurality of streams of the material to ow in the lower portion of a receptacle from the ends thereof toward and somewhat beyond the mid-point, whereby 2o. The method of aisintegraung material" which comprises causing a plurality of streams of the material to iow insthe lower portion o! a receptacle from the ends thereof toward and somewhat beyond the mid-point, whereby said streams moving toward said mid-point from thc. respective ends of the receptacle overlap to some extent at that point, causing a return flow of the material in the opposite directions in the upper' portion oi.' said receptacle, shredding the material by forcing it against a roughened portion of the wall of .said receptacle during its movement along the -lower portion of the receptacle, and eooling said material while it is passing from the center to the ends of the upper portion of said receptacle. A

' JOSEPH L. HUTCHINGS.

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