US2570223A - Mulling apparatus - Google Patents

Description

Oct. 9, 1951 E. EVERETT ETAL 2570223 MULLING APPARATUS Filed July 5, 1948 7 Sheets-Sheet l INVENTfoRS le Boy 'z/erel BY mest @Hand Wyfmi@ Oct. 9, l1951 l.. E. EVERETT ET AL MULLING APPARATUS '7 Sheets-Sheet 2 Filed July 5. 1948 INVENTORS Ielgy I z/ereZ mest CLHLmoL Oct. 9, 1951 Filed July 5, 1948 L. E. EVERETT ET AL MULLING APPARATUS '7 Sheets-S116@JL 5 INVEN T0125 BY m" rnes @Hund MULLING lAPPARATUS '7 Sheets-Sheefl 4 Filed July 5. 1948 INVENTRS .IS Roy gf/enel? rnesz Q. Hund L. E. EVERETT ET AL MULLING APPARATUS 7 Sheets-Sheet INVENTOR-S wbre By 'rle Q'. Hand Mgtwfw Oct. 9, 1951 Filed July 5, 1948 Oct. 9, V1951 1 E. EVERETT ETAL 2,570,223

MULLING APPARATUS Filed July 5, 1948 7 Sheets-*Sheet 6 IN VEN TORS le Roy z/eretf mesi QJ-/and u wat i ,W/ e @zu @5.

Patented Oct. 9, l9 51 MULLING APPARATUS Leroy E. Everett and Ernest A. Hund, Chicago, Ill., assignors, by mesne assignments, to Pettibone Mulliken Corporation, a corporation of Dela- Wavre Application July 3, 1948, Serial No. 37,043

4 Claims.

The present invention relates generally to improvements in mulling apparatus for working sand and other materials.

One of the primary objects of the invention is to provide a mulling apparatus which for its size has an increased operating capacity, reduced power requirements, and improved mulling characteristics.

Another object resides in providing a mulling apparatus with improved mulling and plow assemblies.

A general object is to provide a mulling apparatus which is relatively simple and inexpensive to construct, repair and service, and which is reliable and eiiicient in operation.

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawings:

Figure 1 is a plan view of a mulling apparatus embodying the features of the present invention.

Fig. 2 is a vertical sectional view of the mulling apparatus taken substantially along line 2-2 of Fig. 1.

Fig. 3 is a plan view taken partially in section along line 3-3 of Fig. 2, and illustrating the drive mechanism.

Fig. 4 is a fragmentary plan view illustrating the air supply means.

Fig. 5 is a horizontal sectional view taken along line 5 5 of Fig. 2, and illustrating the bed plate in plan.

Fig. 6 is a fragmentary plan view of the discharge gate and the gate operating mechanism.

Fig. 7 is a fragmentary vertical sectional View taken substantially along line 'I-'I of Fig. 6.

Fig. 8 is a fragmentary sectional view of the gate locking mechanism taken along line 8-8 of Fig. 6.

Fig. 9 is a fragmentary plan view of a sampling mechanism.

Fig. 10 is a side elevational view of one of the plow assemblies.

Fig. 11 is an end elevational view of the plow assembly.

Fig. 12 is a sectional detail view on an enlarged scale taken along line I2-I2 of Fig. 1, and illustrating one of the swivel supports for the mullers.

Fig. 13 is a sectional detail view on an enlarged scale taken along line I3-I3 of Fig. l, and illustrating the mounting support for the plow assemblies.

Fig. 14 is a diagrammatic view illustrating the mulling arrangement in a conventional mulling apparatus.

Fig. 15 is a View similar to Fig. 14, but illus*- trating the mulling arrangement in the present mulling apparatus.

Referring more particularly to the drawings, the features of the present invention are susceptible of use generally in various types of machines commonly employed in material processing industries, and specifically adapted for mixing or plasterizing different kinds of materials. Although capable of such general utilization, the invention is especially adapted for, and hence described in connection with, machines for mull. As is well` with a thin film `of the bonding material or` binder.

The sand muller, constituting the exemplary embodiment of the invention, comprises in general a frame structure including a muller pan I adapted to receive the sand and bonding material in suitable proportions. In the present instance, the pan I has a bottom wall 2 which denes an annular muller track, and which is provided with a discharge gate 3 directly underlying the track. A working unit is operatively supported ,within the pan I for rotation about a central Vertical axis, and includes one or more muller rollers 4 and one or more sets of mixing plows 5 revoluble thereby jointly along the track 2. The rollers 4 are mounted in suspension for vertical movement under the force of gravity to compact and knead the sand against the track,

and the plows5 are constructed and arranged to turn the sand and to direct it into the path of the When the gate 3 is open, the plows 5 serve also to discharge the prepared molding rollers.

sand from the pan I.

The various units making up the muller are constructed almost exclusively of standard parts and stock material which may be readily fabricated and assembled primarily by means of clamping and welding and without the use of special castings. precision fitting of relatively xed elements is substantially avoided, and the cost of manufac` ture and maintenance is kept to a minimum. At the same time, increased strength, simplicity oi design and operating eiciency are obtained.

Considering now the detailed construction dis- As a result, the necessitygfor 3. closed for purposes of illustration of the invention, the frame structure comprises a hollow circular bed plate t disposed horizontally, and preferably constructed of two flat spaced parallel plates 1 and an encircling channel ring 8. The legs of the channel ring 8 project outwardly, and the intermediate wall thereof snugly embraces and is welded to the circumferential edge surfaces of the plates 1 so as to close hermetically the interior space 9 which constitutes a plenum chamber. To afford strength and rigidity, and maintain parallelism, suitable spacers I8 are interposed at spaced points between theY plates 1. In the present instance, each spacerV It consists of a cylindrical plug disposed endwise between the plates 1 and having diametrically reduced end extensions II seated and welded in bores I2V in the opposed plates 1.

The bed plate S constitutes the base support` for the bottom wall 2 of the pan I, and hence is constructed to withstand the -force of the mulling operation. To dei-lne the side wall of the muller pan I, a cylindrical shell I3 issupported on and extends-upwardly from the ring 8 in closely ernbracing engagement' about the uppermost plate 1. Preferably, the ring 8 and shell I3 jointly overlap the edge surface of theuppermost plate 1, and are welded thereto. An angle ring I4`resting on and preferably welded to the upper leg of the channel ring 8 closely encircles and is Welded to the lower marginal edge portion of the shell I3 to provide a rigidv integral construction. The shell I3 may be constructed of sections connected by welded butt joints, and is reinforced by additional angle members I5. To complete the pan construction, a flat annular wear plate I8 is disposed in laminar relation on the uppermost plate 1,'a cylindrical liner member I1 is positioned in laminar relation within the lowermost portion of the shell I3, and anannular fillet member I8 is interposed between the adjoining edges of the elements I6 and I1.

The muller has a base structure I9 (Fig. 3) adapted to be mounted on asuitable foundation, and from which the pan I is supported in elevated position on a plurality of vertical legs 29. In the present instance,the structure I9 is made up of I-beams 2I andchannel members 22 integrally joined together, as by welding, to form a at open horizontalY framework. Preferably, three equilaterally spaced legs 20 are provided so as to afford ample space for operation of the gate 3. Each leg 20 (Fig. 2) comprises a short tubular element 23 iixed'ly attached to the bed plate 5, and a long aligned tubular element 24 removably attached at opposite ends to the element 23 and the base structure I9... The element 23A extends through an opening 25v in the lowermost plate 1 into end abutment with the uppermost plate, and is welded in position. Divider platesV 28 are welded to the adjoining ends of the elements 23l and 24, and are normally bolted together. A foot plate 21 on the lower end ofthe element 24 is bolted to the base structure I9.

The working unit within .the pan I` is supported on the upper endof an axial vertical drive shaft 28 which extends upwardly through the bed plate 6, and which is connected at its lower end through a flexible coupling 29 tothe power outlet shaft 3U of a drive unit 3.I To plovide a rigid and sturdy support, the'shaft 28 extends through and is journalled in both ends of a cylindrical bearing housing 32 projecting upwardly from the bed plate` 6. The lower end portion of the housine 32 iS .eXtBHded thrpugh alignedpenines 33 4 in the plates 1 and welded thereto, and is slightly reduced in diameter to define a peripheral locating shoulder 34 seating on the uppermost plate. Both ends of the housing 32 are formed to receive suitable bearing assemblies 35. These assemblies include anti-friction bearings 38 of the radial and end thrust type, and are constructed and arranged to support the shaft 28 rotatably in fixed axial position. End caps 31, with suitable oil seals, closely receive the projecting ends of the shaft 28, and are bolted in position to close the bearing assemblies against the entry of foreign matter. Suitable provision is made for supplying lubricant to the bearings 36 and for drawing 01T spent lubricant.

The drive unit SI may be of any suitable character but preferably is a self-contained and standard structure which can be readily mounted Y in position or removed fpr purposes of repair or 56. l Y the mulling assemblies 48. so vas to permit the rollreplacement. Because of-this ready interchangeability, maintenance costs are reduced, and loss of operating time can` be kept to a minimum, est` pecially if a spare unit is kept on hand. In the construction as shown, the drive unit 3| comprises a housing 38 mounted on and removablyV bolted to plate 38d on base structure I9. The

power. shaft itY is journalled in axially spacedV bearings 39 within the housing 38, and projects` upwardly therefrom for connection with the shaft 28. A worm wheel 48, fixed on the shaft 30 between the bearings 39, meshes with a worm 4I on a transverse shaft 42, to provide a suitable speedreduction gearing. The shaft 42 isf jour-4 nalled within the housing 38, and projects laterally therefrom for attachment of a multiple 1 groove pulley 42a. An electric drive motor 43, mounted on and removably bolted to a plate 44 on the base structure I9, has a shaft 45 with a multiple-groove pulley 45A connected by V-belts 4.1 to the pulley 42a.

The working unit may comprise any desired number of mulling assemblies 48, each including a muller roller 4 arranged to coact with the bot- A tom wall or track 2. of the pan I. In the present instance, two suchmulling assemblies 48 (Figs. l and 2) are provided, and arranged in diametri cally opposed relation., To provide means of support, a cross head 49 is fixed tol the upper end of the shaft 28, Preferably, the head 49 comprises a flat rectangular plate having spaced parallel depending side flanges 50, and havinga central sleeve 5i tightly fitted on the upper end portion of the shaft 28. A nut 52 threaded onto the shaft 28 serves to clamp the sleeve 5I tightly in posil tion. Two lixed parallel shafts .'53` are clamped to the flanges' equidistantly: from and atopposite sides of the sleeve.` 5I.. More particularly, the opposite ends of each shaft 53 are seated and clamped in semicircular notches 541 in the bottom edge surfaces of the flanges 5I! by means of U bolts 55A having their legs projecting upwardly through suitably located bores to the top of the plate 6.9 for threaded attachmentv of clamp nuts The shafts 53 serve as swivel supports for ers 4 to swing vertically toward and from the track 2.

Each mulling assembly 48 has a swivel sleeve 51 disposed on the associated shaft 53. between the flanges 5B. rIightly secured within the sleeve 1 51 in anyr suitable manner, as by a press iit or by means of a split clamp 58, is a thin metal liner sleeve 59'. The sleeve 59 is rotatable with respect to the shaft 5.3,V but one of the features of the` 1 present invention is to avoid any sliding-cr bears..

ing relationship therebetween. To this end, a resilient rubber sleeve 60 is concentrically interposed between the shaft 53 and sleeve 59, and is securely attached to both members by a rubber to metal bond. Rocking movement thus is permitted by distortion or yield of the stock in the rubber sleeve 6U. As a result, there is no bearing space or clearance whatever into which sand or other foreign matter might enter, and no possibility of the shaft 53 becoming seized and damaged. There can be no scoring, twisting or shearing of the shaft 53 as often occurs in prior construction.

A rocker arm 6|, preferably tubular in form, is rigidly attached at one end, as by welding, to one side or the swivel sleeve 51, and projects laterally therefrom in a generally horizontal direction outwardly over the track 2. A xed axle 62 has a rod 63 tightly secured in the outer end of the arm 6I, and in effect constitutes an aligned extension thereof. The associated muller wheel 4 is rotatably conned on the axle 62 for vertical swing-ing movement and horizontal revolution therewith. Preferably, the Wheel 4 is of heavy solid cylindrical construction provided with a peripheral tire 64 of good wearing and mulling properties, and formed with an axial bore 65 for receiving the axle 62. Suitable ball bearings 66, mounted within the bore H5 and separated by a spacer sleeve 61, serve to journal the wheel 4 on the axle 62. A bearing seal retainer 68, which encircles the rod 63, is bolted to one side of the wheel 4 to close the inner end of the bore 65. The other end of the bore B5 is closed by a hub cover plate b9.

As they revolve, the two mulling assemblies 48 act conjointly to squeeze and smear the sand mixture against the underlying track 2. The required pressure is obtained by reason of the heavy mass of the Wheels 4. 'Io limit downward movement of the wheels 4 and thereby to control the pressure applied to an appropriate charge of sand mixture, suitable positive stop means are provided. The angularity of the active or working faces of the rollers 4 in relation to the horizontal surface of the track 2 may vary somewhat because of the limited swinging movement of the hluller assemblies about the horizontal shafts 53, but not objectionably since these faces will be substantially parallel to the track when the rollers are in their normal working p0- sition.

In order to afford ready accessibility for purposes of adjustment, and to make possible a cross head 4a of simple and compact construction, the aforesaid stop means preferably comprises cross cable connections between the two rocker arms 6l. 'Io this end, an arcuate bridge member 10 is rigidly bolted to the top of the cross head 49 transversely of the shafts 53. In the preferred form, the bridge member 10 comprises two vertical legs 1l connected by an arcuate cross guide 12 of channel shape closed at the top by a curved cover plate 13. For each mulling assembly 48, a cable 14 is suitably attached at one end to the outer end of the rocker arm 6I which it is to control, and is arranged at the other end for coaction with the opposite rocker arm adjacent the swivel axis thereof where the vertical component of movement is slight and inconsequential to provide a limit stop. More particularly, at the stop end, each cable 14 is attached to a bolt 15 which extends slidably through a tubular sleeve 16 xed in and opening diametrically through one of the rocker arms 6I adjacent the associated sleeve 51. outer end of the bolt 15 for abutment with the lower end of the sleeve 16. At the opposite control end, each cable 14 has a loop 18 which extends about the outer end portion of the other rocker arm 6|, and engages a rest 19 on the underside of the latter. It will be evident from the foregoing that the two suspension cables 14. while permitting free upward swinging movement of the mulling assemblies 48, serve to limit the downward movement and to dene the lowermost positions of the respective rollers 4. When the rollers 4 are in normal mulling positions, as shown in Fig. 2, the cables will be slack. However, if the rollers 4 should drop, the bolts 15 will slide upwardly in the sleeves 16 until the nuts 11 abut the sleeves to limit further downward movement. 'Ihe limit stop construction is simple, strong, reliable and readily adjustable.

The working unit also may comprise any desired number of plow assemblies which are revoluble with the mulling assemblies 48. In the present instance, two such plow assemblies 80 are provided, and are arranged preferably in diametrically opposed relation respectively between the mulling assemblies 48. These plow assemblies 80 are alike in construction so that a detailed description of one will suiice for both. They are both supported from the cross head 49 for revolution along the track 2, and serve to turn over the sand mixture, and to direct it from opposite marginal areas of the track into the path of the rollers 4. Preferably, each plow assembly 80 comprises a set of two mixing plows 5 adjustably suspended for movement respectively at the inner and outer edges of the track 2, and adjustable angularly in relation to the direction of travel so as to control the sweeping action as well as the deiiection and turning action. By providing each plow assembly 80 with two plows 5 there is obtained a balanced action on the sand, improved blending and `a minimum expenditure of power.

To provide means of support, the cross head 49 has two narrow plate extensions 8l| projecting radially outwardly from the side flanges 50. Formed in the bottom edge of each ange 50 and in depending lugs 82 on the underside of each extension 8| are three aligned semicircular recesses 83. Each plow assembly 8D has a supporting stub shaft 84 which seats in the recesses 83 and which is adapted to be clamped therein in selected positions of both angular and axial ad- -justment by a plurality of U-bolts 85. These U-bolts embrace the shaft 84 and. have their legs extending upwardly through the cross head 49 for threaded attachment of nuts 86. This clamping arrangement permits horizontal adjustment of each complete plow assembly 80 into the desired position radially of the track 2, and also angular adjustment about a horizontal radial axis to obtain parallelism between the bottom edges of the plows 5 and the track.

Rigidly secured, as by welding, to the outer end of the shaft 84 (Figs. l and 10) is a generally horizontal arm or beam 81 which is preferably inclined to the direction of revolution so that one plow 5 will be in advance of the other. In the present instance, the outermost plow 5 is supported from the leading end of the arm 81, and the innermost plow is supported from the Suitable ,stop nuts 11 are threaded onto the any movable or revolving parts.

trailing Vend .of the arm. Suitable transverse clamp blocks-Sears xed on opposite ends of theV arm 8'!! to affordl means fory adjustably supporting two depending vertical Ashafts 89 for carrying the plows 5.. In each instance, the upper end portion .of the shaft 83 is. clamped `for rotary and vertical adjustmentby a pair of U-bolts di] in ascoli-cylindrical vertical recess 9| in the outer aceoi the associated block 88. The lower ends of the vertical shafts 89 are similarly provided with clamp blocks 82 4for supporting the plow blades 5.. vWhile theV plow blades 5 may be provided nvarious forms, each blade, in the present instance,` comprises an elongated straight plate extending endwise horizontally to sweep along the track 2.. The upper portion of each blade 5 isv at and is removably attached intermediate its ends",` as" by means of bolts s3, to the front face of the associated'clamp block 92. In the Case of the outermost block 92, the bolts Q3 are extended through elongated slots S4' to facilitate horizontal adjustment of the associated plow blade 5. Preferably the lower edge portion of each plow bladeY 5` is curved laterally as indicated at 95 so as to forma scoop. In use, both plow blades may be disposed at any desiredY angleandrnay he located in any desired vertical position with reference tothe surface of the track 2 by adjusting the shafts 89 relative to their supporting blocks 8B. The entire plow assembly B may be positioned radially and. also angularliyby adjusting the stub-shaft 8d so as to. position; the outermostplow to sweep the. peripheral sidewall ci the pan I and to maintain the plow assembly in parallel relation to the track. 2..V The arrangement is such that sand isV directed from thev outer vertical wall of the mullerpan I inwardlyl against centrifugal force and from the central area of the pan outwardly, into the path of the. rollers 4. At the same time, the angleof` the plows may be so adjusted that sand will also be advanced to some extent. circumferentially with the. plow assemblies il!) so as to facilitate. unloading when the mulling operationv has been completed.

Suitable 'means is provided for supplying air under pressure` to the sand' during the mulling operation. This' means is so constructed and arranged that the air is directed from the center' of the pan I in allV directions into intimate contact with theV sand mixture without employing In the preferred form, the air supply mean-s comprises outer concentran eyi. ical shell 9x6 (see Fig. 2J integrally attached to and rising fr m the uppermost plate lL' peripheral-.ly el-ation. about: the lloearing.l housing 32'. Thus, the housing 3.2 and shell S6 serve to define an annular air pas-- sage 91'. An annular series of openingsy SIB in the; uppermost plate 't serve to establish commuuication between the airY passager Gl' and the, plenum chamber Si in thev bed plate 6. The top of the. air passage el is covered, by a conical delector 8.a of somewhat greater diameter than that or the shell 95, andy spaced from the upper edge of the: shell, to define a peripheral air outlet. IIJ. An annular series of partition members I'IlI are secured in the air passage Eil to insure substantially uniform air distribution. While. these members may be of any suitable construction, preferably they consist of flatv radial plates (see Fig. 5)'. The upper ends of the members LUI have vanes lli-2. which project outwardly through the air outlet. Ill tothe periphery of the,` conical dellector 99, and ,which are curved.

or inclined tothe radial in the` direction of mullet? operation so as to cause the issuing streams of air to swirl about-the panY I.. Thus, the. air is. directed downwardly by the deflector 99 and circumferentially by the inclined vanes L02. of. the radial partition members Il into intimate. contact with the sand mixture. Any tendency of. the air to pass directly upwardly and out of the. pan I without -rstbeing brought into. intimate contact with the sand mixture is effectively overcome. Y Y z Air may be supplied from any suitable source and may be induced to ow through the` pan t.. by any suitable means. In the present instance, a suitable blower Il03 (see Fig. d) driven by an. electric. motor [9.4 is mounted in position alongside the mulling apparatus andr has a pressure discharge duct H15- connected to the plenum chamber 9..

To. facilitate checking of the condition of Athe sand during the mulling operation., a sampler ld (Figs. 2 and 9) is. operatively mounted in. one side of the Vertical wall. of the pan lr In the present instance, the sampler Ille comprises a cylindrical drum I'I which. is supported for rotation on the exterior ofthe pan. I, and. which. has a portion` of its periphery projecting through an. opening IGS inthe shell I3 and wear plate I1 into the interior- The. drum IUT has an axial stubshaftL H19 on the bottom and projecting downwardly through. a suitable bearing lug linon. the shell i3. An eccentric handle` I.II on the top of-the drum Illl attords means. for effecting rotary adjustment of the sampled selectively into open or closed position. A spring strap lI.2 attached to the shell I3 is fixed to exert a friction drag on the periphery of the drum I01 so.

` as to prevent inadvertent. rotation of, the. sam-.

pler. The drum ISI is` formed with a segmental. pocket H3. closed at the bottom, and open at the, top and periphery. In use, the drum ID'I is rotated into open position in which the pocket H3 opens. to the interior of the pan I in position to catch a sample of. the sand. In closed position, the drum IGI is rotated to locate the pocket I' 3 outside of the pan I. Suitable stops II4A fixed on the bottom of the drum IDT are movable selectively into abutting engagement' with the exterior of the shell I3 to denne the open and closedv positions ofthe sampler.

Located in the bed plate 6 of the pan I to open downwardly from the mulling track 2 is the discharge gate 3 (Figs. 2, 6 and 7 In the preferred form, the gate 3 comprisesa segmental gate memberY H5 the .form of a plate which is adapted to interi-'lit' in adischarge opening IIB ot complemental shape in the. bed. plate. VThus', when: closed,..the gate. member IIE defines. part or the track 2. and is. subjected to the pressure exerted-L by the mull'er rollers 4.. Accordingly,v the: gate. member'.` H5. is supported for swinging movement into. open and closed position, and.- is. providedwittr power actuating means and a sturdy locking: means; to withstandv this pressure.. By locating' thev gate 3i directly in. the path of the muller roll-,-4 ers'. 4ya. tast. rate of.rdischarge is possible.. Also.. the muller rollers 4 may be located apart to have alarge circle of revolution and thereby to. increase. the efective` area oi the track 2 and to reduce thawidth ofi the dead area. between the. track and.

the shell I3., Preferably, though notl necessarily-,.Y

therollers 4 are located at equal; distances from the` axislof-l revolution. andthe discharge opening. ILS; is slightly offset from the. track. 2 so thatthe present instance, the bearings I9 are xed to an angle bar |26 bolted to the top plate 1 and to a member of a frame l2| set in the plenum chamber 9 and sealing the latter at the discharge gate 3. The shaft ||8 thus defines an axis about .which the gate member is hinged for swinging movement selectively into open or closed position. Offset stop lugs |22 on the free ends of the arms H1 are adapted to engage the bottom of the channel ring 8 to dene the closed position.

The power operating means for the gate member ||5 may be of any suitable character, and preferably is actuated by fluid under pressure. In the present instance, twopressure fluid actuators |23 of the piston and cylinder type are supported from the underside of the lower bed plate 1, and are operatively connected in parallel balanced relation to the gate member H5. Each actuator |23 has a piston rod |24 pivotally connected by a clevis |25 to a depending arm |25 on the associated hinge arm ||1. To accommodate the arcuate movement of the pivot connections between the arms |1 and rods |24, the actuators |23 are supported intermediate their ends for swivel movement from trunnions |21 on the underside of the bed plate 6.

The locking means (Figs. 6 and 8) for maintaining the gate member ||5 securely in closed position during the mulling operation comprises a. plurality of locking bolts |28 adapted to coact with fixed keepers |29 within the bed plate 6 adjacent the channel ring 8. In the present instance, two bolts |28 are provided. Each bolt |28 is reciprocable in a guide sleeve |32 secured by a bracket |3| to the underside of the door plate of the member ||5. The related keeper |29 preferably consists of a locking sleeve axially aligned with the sleeve |30 and secured by a bracket |32 to the top of the lowermost plate 1.

Power actuators |33, preferably of the reciprocatory pressure fluid type, are provided for shifting the bolts |28 simultaneously either to project them into keepers |29 so as to lock the gate meinber I5 in closed position, or to retract them so as to release the gate member 5 for opening moven ment. Thus, each actuator |33 is bolted to the underside of the door plate, and has a piston rod |34 rigid with the associated bolt |28. The pressure fluid may consist of compressed air adapted to be supplied selectively to opposite ends of the actuators |33 by a remote control (not shown). The locking bolts |28 afford a very strong support for the gate 3 so as to withstand the pressure of the mulling action as the muller rollers 4 pass thereover.

To provide means for supplying water or some other desired liquid to the material being worked, a vertical supply pipe |35 extends through and is fixed in the top arch of the bridge 1li. The lower end of the pipe |35 is connected by a huid-tight swivel coupling |135 to a pipe manifold |31 having branches extending to the plow beams 81 which are hollow. Suitable spray nipples |38 open from the interior of each beam 81 to discharge the liquid into the pan It will be evident that we have provided a new and improved muller which for a given pan diameter has an unusually large operating capacity, and is capable of a rapid and efficient mulling action. 4These advantages characteristics are attrbutable in some measure to an increase of the track area traversed by the muller rollers 4 which subjects a larger volume of material to the mulling action per revolution, and to reduction of the dead outside floor areawhich reduces the volume of material that must be moved `inwardly by the plows 5 against the action of centrifugal force, and which therefore permits increased speed of revolution. To illustrate the foregoing, Fig. 14` `represents a conventional muller of standard size having two muller Wheels 4d andv4b traversingV respectively `overlapping tracks 2a and 2b, and having discharge gates 3a located outside of the tracks. To avoid transversing the gates 3a, the tracks are located close `to the center, and therefore have a relatively small aggregate area, and leave a relatively wide and large encircling dead area `|39a. In fact, each of the tracks 2a and A2b is considerably narrower than the area |39 so that a large quantity of material spilling to the dead area must be moved inwardly in the course of the mulling operation. This diiiiculty is even more pronounced for the track .2u than -for the track 2b. In contrast, Fig; 15 represents a muller of somewhat smaller size embodying features of the present invention.` In this instance, the muller rollers 4 are located at equal radial distances from the center axis so that their tracks 2 coincide. This is not essential, but is desirable in order that both rollers will describe the maximum circle :of revolution. ,In any event, the joint track 2 extends over the discharge gate 3. and hence has a large diameter-and a correspondingly large aggregate area` As a result, the

.encircling dead area` |39 `is comparatively small,

and is considerably narrower than the track area. The discharge gate 3, being directly in the path of the rollers 4 facilitates a quick and convenient discharge of thenished material. To preclude any possibility of the` rollers 4 entering the gate opening ||6, the innergedge'of the track 2 is located slightly'inwardly .of the gate 3. Although the muller of the present invention is smaller in diameter and has narrower rollers than the conventional muller, it has a considerably larger effective track area, and a considerably smaller outside dead area, and can be operated efficiently with less power at a higher R. P. M.

If desired in certain uses of the muller the chamber 9 may be designed to receive a vheating medium for imparting heat to the bottom wall of the pan We claim as our invention:

1. A mulling apparatus comprising a .mulling pan having a bottom wall defining an annular mulling track, a central vertical drive shaft extending upwardly into said pan, a cross head fixed on the upper end of said shaft, two diametrically opposite muller assemblies mounted on said cross head for revolution therewith and for vertical swinging movement relative thereto, each mulling assembly including a muller roller revoluble along said track, and two suspension cables extending loosely and slidably over said cross head and serving to limit vertical swinging movement of said muller rollers, said cables being reversely positioned and each having one end anchored to one of the assemblies and its other end operatively and adjustably connected to the other assembly.

2. A mulling apparatus comprising a mulling pan having a bottom wall defining an annular mulling track, a central vertical drive shaft exassocie jtend-inghpward'ly into A'said pan, a ycross head xed on the -upper end of said shaft, two ldiametrically opposite lrnuliing *assemblies mounted on saidfcross head Vfor revolution therewith and lfor i vertical swinging movement relative thereto, each ,molli-ng assembly comprising a rocker arm having -a swivelV mounting -on saidhead and extending outwardly therefrom and a muller roller supported from th'eree end 'of said arm for movement along said track, and two suspension cables extending loosely and slidably over said A'jcrosshead and serving to limit downward move- Yment of said 'muller rollers, said cables being reversely arranged and each having one end thereof anchored to 4the free end of one of the rocker arms and its other end operatively and adiustably connected 'to the other rocker yarm at -a'point Yawljacen't its swivel axis.

3. A mulling apparatus comprising in combination -amull'ing -pan having a bottom wall delining an annularmuller'track, `a central drive 'shaft l'extending upwardly into said ipan, a cross head fixed on the upper 'end of said shaft, a mulling assembly -carried byrsai'd cross head for `revolution therewith and including a muller roller supported for movement along said track, a plow Aassembly carried by said cross head and including inner and outer plows movable'along said track, said plow assembly comprising a supporting stub shaft clamped to sai-d cross head for `radial and rotary adiustment, an incl-ined plow arm rigid with said stub shaft and 4extending @diagonally in a generally horizontal plane across said track, two ver-tical depending sha-fitsV adjustaf'bly clamped `respectively :to v-oirposite ends of said arml for angular and vertical adjustment, and two elongated "plow blades removably connecte'd respectively tc the lower ends of said ver-- tical shafts, one blade being located at the inner circumference of said track and inclined to direct sand outwardly, the other blade zbeing located at the outer circumference 4of said track and being inclined to direct the ysand inwardly,

fi. A mulling {appara-'tus comprising in combination, La mulling pan having ra 'bottom wall de'- ning an annular mulling track, a central idr-ive shaft extending upwardly into said pan, across -head fixed on `the upper end .of said shaft, a plurality of mulling assemblies carried by Isaid -cross head for revolution therewith Iand each `including a muller roller supported for 'movement along said track, a plurality of plow assemblies carried by said cross head between said mullin'g assemblies and each including inner and outer -ploWs movable along said track, each plow assembly comprising a supporting stub shaft clamped to said cross head vfor axial adjustment, an inclined plow varm rigid with said stub shaft and extending Ydiagonally in a, generally horizontal plane across said track, two vertical depending shafts Vadjust'ably clamped respectively to REFERENCES CITED 'The following references are of 'record inthe Y le of this patent:

UNITED STATES PATENTS Number Name Date 566,777- Layng Sept. 1, 1896 1,857,337 Simpson May 1.0, 1932 1,910,028 McElroy May 23, 1933 1,931,150 McElroy et al Oct. 1'7, 1933 1,955,841 Tryon Apr. '24,1934 1,969,523 Rapp Aug. '7, T1934 2,103,895 'Christensen Dec. .28, 1937 2,309,036

Beardsley Jan. 1'9, 1943

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