US3408052A

US3408052A - Method of mulling

Info

Publication number: US3408052A
Application number: US549331A
Authority: US
Inventors: Cecil E Simmons
Original assignee: Jeffrey Galion Manufacturing Co
Current assignee: Jeffrey Galion Manufacturing Co
Priority date: 1963-12-27
Filing date: 1966-05-11
Publication date: 1968-10-29
Anticipated expiration: 1985-10-29

Description

Oct. 29', 1968 c. E. slMMoNs 3,408,052

, METHOD OF MULLING CEcu E. IMMONS,

Ci.` E. SIMMONS METHOD 0F MULLING Oct. 29, 1968 4 Sheets-Sheet 2 Original Filed Dec. 27. 1963' CEcnL ESMMONS INVENTOR;

B? qw Oct. 29, 1968 c. E. SIMMONS METHOD OF MULLING 4 Sheets-Sheet 5 Original Filed Dec. 27. 1965 INVENTOR; CECIL. ESIMMONS, BY o TTY.

Oct. 29, 1968 c. E. SIMMONS 3,408,052

METHOD OF MULLING Original Filed Dec. 27. 1963 4 Sheets-Sheet 4 Eig. .9

3 INVENTOR; 23 CEcn. ESIMMONS,

HTT'Y United States Patent O 3,408,052 METHOD OF MULLING Cecil E. Simmons, Durham County, Ontario, Canada, assignor, by mesne assignments, to Jeffrey Galion Manufacturing Company, a corporation of Ohio Original application Dec. 27, 1963, Ser. No. 333,937, now Patent No. 3,321,187, dated May 23, 1967. Divided and this application May 11, 1966, Ser. No. 549,331

2 Claims. (Cl. 259-147) This is a division of patent application Ser. No. 333,937, led Dec. 27, 1963, now Patent No. 3,321,187, for Continuous Muller and Method of Mulling.

The instant invention relates to the mulling of sand and like materials, and more particularly, to an improved method of mulling such material.

This invention has application to the preparation of materials, such as sand, to place the same in suitable condition for use in making molds in metal casting operations. Such preparation of sand may involve new sand which has not previously been used in molds, recirculated sand which has been used in molds and is circulated in the foundry system for reuse, or a combination of the two. In any of these cases it is required in the preparation of the sand for use in making molds that the sand be mulled, which involves adding to the sand and combining therewith certain ingredients, particularly water and bonding agents. In the mulling operation these ingredients are uniformly combined with the mass of sand, and in an ideal operation each grain of sand is cornpletely and uniformly coated with the added ingredients, whereby the mass of sand discharged from the mulling operation has the necessary bonding characteristics, such that it may be formed into molds into which hot molten metal may be poured.

The mulling of the sand is essentially a pressing, kneading and mixing operation in which the sand and the added ingredients are constantly being mixed and pressed together, until the added ingredients are uniformly dispersed in the mass of sand and the grains of sand are each coated with the bonding materials.

Heretofore, most mullers in operation have been those referred to as the batch-type muller. These are normally fed a specific charge of sand which is worked and operated upon and then discharged. A new charge is then fed into the muller and the operation is repeated. The use of such batch-type mullers requires auxiliary equipment such as storage hoppers to derive the desirable level of use. Moreover, other auxiliary equipment such as aerators and extensive conveying equipment is necessary. All of this auxiliary equipment adds considerably to the cost of sand preparation in most foundaries. Further, operations in many foundaries have tended toward a continuous molding operation which requires large quantities of sand to be continuously fed into this operation. To derive an adequate capacity from batch-type mullers, more than one muller is often required or a muller of extremely large capacity is often used. In either case, the investment in such mullers in both money and space is considerable.

In recent years there have been attempts to make a continuous muller by joining two batch-type mullers, but the size and expense of such a device with its auxiliary equipment is greater than is contemplated by the present invention with any auxiliary equipment which might be necessary.

In mulling operations in which for practical economic reasons recirculated sand is being operated upon, such 3,408,052 Patented Oct. 29, 1968 ICC sand is usually very hot as the result of being in contact with hot molten metal. It is recognized in the foundry industry that sand at very hot temperatures is extremely diilicult to mull. In such case, it is necessary that the sand be cooled and this may be accomplished during the mulling operation by circulating air through the sand. Also, in connection with the preparation of the sand for the making of molds, it is desired that the sand be aerated, which consists essentially of breaking up any lumps in the sand and placing the mass of sand in a fluffy, uniform condition of a proper porosity, in which it may be readily and uniformly packed around a pattern in the process of making a mold with such sand. Aeration of the sand is accomplished during the mulling operation by the apparatus and method of this invention.

It is a prime object of the instant invention to provide an improved method for the preparation of sand for the making of molds as above stated.

It is also an object of the instant invention to provide an improved continuous mulling method, in which the mulling operation also has the effect of aerating the sand as it is being mulled.

Still a further object of the instant invention is to provide an improved continuous mulling method, in which the sand may be cooled as it is being mulled.

It is still another object of the instant invention to provide an improved method of continuously mulling sand in which the sand is progressively mulled as it is fed along a path from a feed position to a discharge position.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings:

FIG. 1 is a longitudinal elevational view of a continuous mulling apparatus constructed in accordance with this invention;

FIG. 2 is an end elevational view of the mulling apparatus, Viewed from the discharge end thereof;

FIG. 3 is a longitudinal sectional view of the mulling apparatus;

FIG. 4 is a lateral sectional View of the mulling apparatus, taken on the line 4--4 in FIG. 3;

FIG. 5 is an illustration of the mulling wheels and supporting structure therefor, partially in section, taken on the line 5-5 in FIG. 4;

FIG. 6 shows the rotating seal for a mulling wheel;

FIG. 7 shows the adjusting means for the plows;

FIG. 8 is another illustration of the adjusting means for the plows, taken on the line 8-8 in FIG. 7;

FIG. 9 is a transverse sectional view of the mulling apparatus, similar to FIG. 4, but illustrating a modification thereof;

FIG. 10 is an enlarged illustration of the adjusting means for the mulling wheels shown in FIG. 9; and

FIG. 11 is a sectional view of the adjusting means for the mulling wheels, taken on the line 11-11 in FIG. 10.

Referring to the drawings, particularly FIGS, 1 and 2, there is illustrated therein mulling apparatus constructed in accordance with the instant invention, and forming an exemplary embodiment thereof. Such mulling apparatus comprises a cylindrical drumr20, which is horizontally dispoed and forms a receptacle within which the sand is mulled. The cylindrical drum 20 is provided with a supporting base structure 21 which comprises a plurality of transverse I-beams 22 disposed at equidistantly spaced points along the length of the drum 20, with the bottom of the drum 20 being seated on and bearing on the tops of the I-beams 22. A pair of channels 23 are disposed, one at each side of the drum 20, with the I-beams 22 extending laterally between such channels 23. Each channel 23 stands in contact with the drum 20 along a longitudinal line. A plurality of gussets 24 are disposed between the top of each channel 23 and the drum 20, with the gussets 24 being shaped to be in contact with the outer surface 0f the `drum 20. The several elements of the supporting base structure 21, including the I-beams 22, the channels 23 and the gussets 24, are secured to each other and to the drum 20, as by welding, to form the same into a unitary assembly.

The cylindrical drum 20 is formed in two drum portions divided on a horizontal diametral plane defining a parting line 31. The lower drum portion 25 is secured to the supporting base structure 21, as above described, and is fixed. The upper drum portion 26 forms a cover for the mulling apparatus and is secured to the lower drum portion 25 by a longitudinally disposed hinge 27, whereby the upper drum portion 26 may 'be conveniently swung upwardly and raised about the longitudinal axis of the hinge 27. This permits the cylindrical drum 20 of the mulling apparatus to be opened, providing access to the interior of the same, for the purpose of repairing or replacing elements thereof, as may be required from time to time, and for the further purpose of cleaning the mulling apparatus.

At the side of the cylindrical drum 20, Opposite the hinge 27, the lower drum portion 25 has secured thereto a longitudinally extending ange 28, and the upper drum portion 26 has secured thereto a longitudinally extending flange 29. The

lianges

28, 29 may be secured to the respective lower and

upper drum portions

25, 26 by welding. The

fianges

28, 29 are alike and are disposed in alignment with each other. The

flanges

28, 29 are bored at a plurality of equidistantly spaced points, and a plurality of bolts 30 are passed through the

anges

28, 29, and are drawn up securely against the

flanges

28, 29 to firmly and fixedly secure the upper drum portion 26 to the lower drum portion 25. It is essential that the cylindrical drum 20 be sealed along the parting line 31 between the lower and

upper drum portions

25, 26, to prevent sand being thrown out of the drum 20. Suitable sealing means may be provided at the parting line 31 between the lower and

upper drum portions

25, 26, and the several bolts 30 maintain the respective drum portions closed and in sealed engagement with each other along the parting line 31.

In the mulling apparatus the cylindrical drum 20 forms a closed receptacle within which the sand is mulled. The cylindrical drum 20 is disposed in a longitudinally extending position on a horizontal axis. The sand to 'be mulled is delivered to the cylindrical drum 20 at the feed end 32 thereof, this being the left end of the mulling apparatus, as viewed in FIG. 1, and the sand is discharged from the mulling apparatus at the discharge end 33, this being the right end thereof, as viewed in FIG. 1. The sand moves continuously within the drum 20 from the feed end 32 to the discharge end 33. During such movement of the sand it is progressively mulled, so that upon discharge the sand is in proper condition for use in the making of sand molds.

The disposition of the cylindrical drum 20 in a longitudinally extending position on a horizontal axis is a preferred disposition of the cylindrical drum 20. However, the cylindrical drum 20 may also be disposed on an axis that is inclined downwardly towards the discharge end 33, in which case the rate of feed of sand will he somewhat decreased. A determining factor will be the difference in head between the inlet chute 34 and the discharge chute 35. Whether the cylindrical drum 20 is to be disposed on a horizontal axis or an inclined axis is determined by the operating conditions of a particular installation.

At the feed end 32 there is provided a downwardly directed chute 34, through which the sand flows into the cylindrical drum 20. The sand to be mulled may be continuously delivered to the chute 34 by means of a belt conveyor, or other continuously operating conveying clevice, whereby the sand will flow in a continuous stream to the chute 34 and into the cylindrical drum 20 in a longitudinal or axial direction, being progressively mulled during such movement, and finally discharging at the discharge end 33 of the mulling apparatus. At the discharge end 33 a downwardly directed discharge chute 35 guides the discharging flow of sand from the cylindrical drum 20. The discharge chute 35 may have associated therewith a belt conveyor, or other continuously operating conveying device, onto which the sand discharges from the chute 35 to continuously remove the sand after it has been mulled.

Referring now, additionally, to FIGS. 3 and 4, wherein the mulling apparatus is illustrated in greater detail, it is seen therein that the cylindrical drum 20 has a cylindrical shell that is in two half portions, there being a lower shell portion 38 for the lower drum portion 25, and an upper shell portion 39 for the upper drum portion 26. At the feed end 32 the cylindrical drum 20 has an end plate of a substantially disc configuration, that includes a lower plate portion 40 and an upper plate portion 41, for the lower and

upper drum portions

25, 26, respectively. Similarly, at the discharge end 33 of the cylindrical drum 20 there is provided an end plate of a substantially disc configuration comprising a lower end plate portion 42 and an upper end plate portion 43 for the lower and

upper drum portions

25, 26, respectively. The lower

end plate portions

40, 42 are secured to the lower shell portion 38, as by welding, to form the lower drum portion 25, which is fixedly secured to the supporting base structure 21. The upper end plate portions 41, 43 are secured to the upper shell portion 39, as by welding, to thereby form the upper drum portion 26, which is hingedly connected to the lower drum portion 25, to permit the former to be raised.

The feed chute 34 is secured to the upper end plate portion 41, as by welding, and connects to a feed opening 44 therein, through which the sand ows into the cylindrical drum 20. The discharge chute 35 is secured to the lower end plate portion 42 and leads from a discharge opening 45 therein, through which the sand discharges from the drum 20 to the discharge chute 35.

A support stand 46 is secured to the cylindrical drum 20 at the feed end 32 thereof. Such support stand 46 may comprise a pair of side plates 47, which are laterally spaced with respect to each other, and a top plate 48 which extends across the tops of the side plates 47 to form a platform. The side plates 47 and the top plate 48 may be secured to each other and to the lower end plate portion 40, as by welding, to thereby form the fixed support stand 46. A bearing 49 is mounted on the support stand 46 and is fixedly supported thereby, the bearing 49 being secured to the top plate 48 of the support stand 46, as by a plurality of bolts 50.

At the discharge end 33 of the cylindrical drum 20, the opposite side channels 23 extend in a longitudinal direction beyond the lower end plate portion 42 and beyond the discharge chute 35. A transversely disposed I-beam 51 is supported on the tops of the side channels 23, and is secured thereto, as by welding. The transverse I-beam 51 forms a support stand for a bearing 52 that is similar to the bearing 49. The bearing 52 is fixedly secured to the top of the I-beam 51 by a plurality of bolts 53.

A shaft 54 extends through the cylindrical drum 20, the axis of the shaft 54 being coincident with the axis of the drum 20. The lower and upper end plate portions 40, 41 include a circular opening 55 of substantially the same diameter as the diameter of the shaft 54, and similarly, the lower and upper

end plate portions

42, 43 include a circular opening 56 of substantially the same diameter as the shaft 54, through which the shaft 54 extends in opposite directions. The opposite ends of the shaft 54 project beyond the feed end 32 and the discharge end 33 of the cylindrical drum 20, and are rotatably received and supported in the

bearings

49, 52, respectively.'

At the feed end 32 of the drum 20 the shaft 54 includes a conduit 57 extending through the center of the shaft 54 and along its axis.'Said conduit 57 connects to radially disposed discharge ports 58 in saidl shaft 54, which are disposed inwardly of the lower and upper end plate portions 40, 41. Water and bonding materials, the latter comprising, for example, sea coal and bentonite, may be fed into the cylindrical drum through the conduit 57 and discharge ports 58. To facilitate the feed of these ingredients, the bonding materials may be premixed with the water to form a slurry. Also, the quantity of each of the ingredients added to the raw sand may be controlled by small screw conveyors, or like feeding devices, the speed of which may be determined in proportion to the ampere draw of the motor which is used to drive the mulling apparatus. Thus, the rate of feed of the ingredients is determined by the load on the drive motor, which in turn is determined by the amount of sand going through the mulling apparatus. As the shaft 54 rotates, the transverse or radial discharge ports 58 will likewise rotate about the drum axis, so that the waterV and bonding materials will be dispersed in a full circle.

At the discharge end 33 of the cylindrical drum 20 the shaft 54 projects beyond the bearing 52 and is formed with a keyway 59 for connectingthe drive to the projecting end of the shaft 54. Such drive meansmay comprise the customary couplings, reducer and motor, which are normally utilized for driving rotary apparatus. Such driving means is not specifically illustrated herein, for the reason that it may take any of a number of forms, as determined by the drive requirements of a specific unit of the mulling apparatus, and by the choice of the operator of the same.

Each of the lower drum portion and the upper drum portion 26 has a yieldable liner 60, which is formed of rubber or like yieldable material. The liners-60 are bonded to the lower and

upper shell portions

38, 39, or otherwise secured thereto, in such manner as to be united with the lower and

upper shell portions

38, 39. The yieldable liners 60 are of substantial thickness, as particularly seen in FIGS. 3 and 4, and the surface thereof is the inwardly facing surface of the vcylindrical drum 20. As will appear hereinafter,- during the mulling operation the sand is dispersed within the cylindrical drum 20 and is distributed therein on the inwardly facing surface of the cylindrical drum 20, with the mulling of the sand taking place on such surface and against the yieldable liners 60.

Within the cylindrical drum 20, there are provided a pair of mulling wheels 61 and an associated pair of plows 62, at the feed end 32 of the cylindrical drum 20. A second pair of mulling wheels 63 and a second pair of plows 64 associated therewith, are provided at a position somewhat further removed in an axial direction from the feed end 32 relative to the first pair-of mulling wheels 61 and the first pair of plows 62. The pair of mulling wheels 61 is disposed at one side of the shaft 54, and the pair of mulling wheels 63 is disposedat the opposite side of the shaft 54, at opposite diametral positions. The respective pairs of plows 62, 64 are likewise disposed at opposite diametral positions. Further, the respective wheelsl of the pairs of mulling wheels 61, 63 are alternated with respect to each other in an axial direction, as seen in FIG. 3. Likewise, the respective plows of .the pairs of plows 62, 64 are alternated with respect to each other in an axial direction, with each plow of the pairs of plows 62, 64 being disposed in circumferential alignment with a mulling wheel of the pairs of mulling wheels 61, 63, and behind such mulling wheel in the direction of movement thereof about the axis ofthe shaft 54.

Referring particularly to FIG. 3, there are further provided two pairs of mullingwheels 61a, 61b, which are similar in all respects to the pairs of mulling wheels 61. Associated therewith are pairs of

Yplows

62a, 62b,

which are similar in all respects to the pair of plows V62. The six plows are numbered consecutively 117, 118, 117a, 118a, 117b, and 118b. The pairs of mulling wheels 61a, 61b and the pairs of

plows

62a, 62b are disposed at axially spaced positions along the shaft 54, with the spacing between the individual mulling wheels and the individual plows along the shaft 54 being equal. The pairs of mulling wheels 61a, 61b and the pairs of

plows

62a, 62b have the same circumferential disposition relative to the shaft 54, as do the pair of mulling wheels 61 and pair of plows 62, respectively.

There are further provided pairs of mulling wheels 63a, 63b and Ipairs of plows 64a, 64b disposed at axially spaced positions along the shaft 54. The individual wheels of the pairs shown as 63, 63a, and 63b`are individually numbered progressively as 160, 161, 162, 163, 164 and 165. The individual plows of the pairs '64, 64a and 64b are individually numbered progressively as 170, 171, 172, 173, 174, vand 175. The spacing between the individual wheels of the pairs of mulling

wheels

63, 63a, 63b and between individual plows of the pairs of

plows

64, 64a, 64b is the same, and the pairs of mulling wheels 63a, 6317 and the pairs of plows 64a, 64b are disposed in the same circumferential position relatively to the shaft 54 as the pairs of mulling wheels 63 and pairs of plows 64. Thus, the several mulling wheels and several plows are disposed within the cylindrical drum 20 along the shaft 54, and are alternated with each other on opposite sides of the shaft 54 to continuously operate on the sand as it moves through the cylindrical drum 20 in an axial or longitudinal direction from the feed`endp32 to the discharge end 33, as will be explained in greater detail hereinafter. With the arrangement of the plows as described and illustrated in Vthe drawings, there are no dead spots, thereby providing for maximum effectiveness of the plows.

Each of the mulling wheels -155 inclusive and 160- inclusive are of the same construction and each pair of mulling wheels such as 61 and its associated pair of plows such as 62 is mounted on the shaft 54 by the same supporting structure. The plows, however, are of two different configurations. The plows 117, 118, 117a, 11811, 117b and 118b have a somewhat concave configuration on the sand engaging face while the plows -175 inclusive have a somewhat convex configuration on the sand engaging face. The purpose of these differing plow shapes will be explained in connection with the explanation of the operation of the machine hereafter.

As best seen in FIGS. 3 and 4, a pair of axially spaced

hubs

65, 66 are mounted on the shaft 54. The

hubs

65, 66 are alike, and each has a substantialy triangular configuration and is formed with a bore 67 of substantially the same diameter as the shaft 54, and within which the latter is received. The

hubs

65, 66 are aligned with each other and are fixedly secured to the shaft 54 in axially spaced positions, as by welding. Referring also to FIG. 5, it is seen that the

hubs

65, 66 are formed with like bores 68, 69, respectively, within which there are press-fitted

respective bearing bushings

70, 71. A pivot shaft,y 72 extends laterally

Vbetween thel hubs

65, 66 in the bearing

bushings

70, 71, and is pivotally supported therein. The opposite Vends of the pivot shaft 72 extend beyond the

hubs

65, 66 to receive

opposite washers

73, 74, which are secured to the opopsite endsof the pivot shaft 72, as by welding, to secure the latter in axially fixed position on the

hubs

65, 66. v

A supporting arm structure 75 is secured to the pivot shaft 72, and mounts the pair of mulling wheels 61 on saidl pivot shaft 72 for swinging movement of the mulling wheels towards and away from the inwardly facing surface of the cylindrical drum 20.

The supporting arm structure 75l comprises spaced

arm

76, 77. At one end of the

arms

76, 77 there is integrally formed one-half of a sleeve 78, and at the opposite ends thereof there is integrally formed a similar sleeve 79. The sleeve half 78 has integral, oppositely extending flanges 80, and the sleeve half 79 has similar integral, oppositely extending flanges 81. This part of the supporting arm structure 75 may be formed as a cast element. The sleeve half 78 is placed on the pivot shaft 72 between the

hubs

65, 66. A like sleeve half 82 is placed on the pivot shaft 72 at the opposite side thereof, and forms a cap for the sleeve half 7 S. The sleeve half 82 is formed with integral, oppositely extending flanges 83, which abut the opposite anges 80. The

flanges

80, 83 are bored in alignment to receive bolts 84, by which the sleeve halves 78, 82 are secured to each other and to the pivot shaft 72. Thus, the supporting arm structure 75 is swingably mounted on the

hubs

65, 66 by the pivot shaft 72.

At the other end of the supporting arm structure 7S a shaft 85 is received in the sleeve half 79. A similar sleeve half 86 overlies the shaft 85 and forms a cap for the sleeve half 79. The sleeve half 86 is formed with integral, oppositely disposed flanges 87 which abut the anges 81 of the sleeve half 79. The flanges 81, 87 are bored in alignment to receive bolts 88, by which the sleeve halves 79, 86 are secured to each other and fixedly secure the shaft 85 to the outer end of the supporting arm structure 75. The shaft 85 extends beyond the supporting arm Structure 75 at each side thereof, and the

individual mulling wheels

150, 151 of the pair of mulling wheels 61 are-mounted on the opposite ends of the shaft 85.

Referring particularly to FIG. 5, there is illustrated therein, in detail, the means by which the mulling wheel 151 is rotatably mounted on the projecting end of the shaft 85. It will be understood that the mulling wheel 150 is rotatably mounted in the same manner on the opposite projecting end of the shaft 85. The mulling Wheel 151 has a solid hub 91, which is preferably formed of metal. The hub 91 is provided with a centrally disposed bore 92, into which the projecting end of the shaft 85 extends. A pair of tapered roller bearings 93 are disposed in axially spaced positions between the shaft 85 and the bore 92, and are press fitted on the shaft 85 and in the bore 92 in the customary manner, whereby the mulling wheel is rotatably mounted on the shaft 85. The assembly of the mulling wheel 151 on the shaft 85 is secured by a suitable locking nut 94, that is engaged with the threaded end of the shaft 85. The bore 92 is closed and sealed by a cover 95, which may be of a simple disc form. The cover 95 is secured to the hub 91 by a plurality of bolts 96, which may be four in number. To assure a positive seal between the cover 95 and the hub 91, an O-ring 97 is interposed between the cover 95 and the hub 91. Such sealing of the bore 92 prevents the entrance of sand and dust, and protects the bearings 93.

At the opposite end of the bore 92, it is required that there be provided a rotating seal between the bore 92 and the shaft 85, also for the purpose of preventing the entrance of sand and dust into the bore 92. Such rotating seal is illustrated in detail in FIG. 6. A bushing 98 is press fitted to the shaft 85 at the inner end of the bore 92. A pair of flexible annular seals 99 are oppositely disposed in the bore 92 and extend inwardly into engagement with the bushing 98, to provide the required rotating seal between the mulling wheel 90 and the shaft 85.

The mulling wheel 151 has a tire 100 formed of rubber, or like yieldable material. The tire 100 is bonded to an annular band 101, which may be formed of metal. The tire 100 is then mounted on the hub 91 by press fitting the annular band 101 on the periphery of the hub 91. In the mulling operation, the sand is mulled between the yieldable tire 100 and the yieldable liner 60, which forms the inwardly facing mulling surface of the cylindrical drum 20. By having the mulling take place between two yieldable members, the one being the liner 60 and the other being the tire 100, the wear of these elements is materially reduced, which is an important consideration in that the maintenance requirements of the mulling apparatus is thereby reduced.

The pair of plows 62 -are also mounted on the hubs 657 66, at the other corner thereof, as best seen in FIG. 4.

Such mounting of the pair of plows 62 is illustrated in greater detail in FIG. 7. The

hubs

65, 66 are formed with like

bores

102, 103, within which there are secured bearing

bushings

104, 105, respectively. A pivot shaft 106 extends laterally between the

hubs

65, 66 and is pivotally received within the bearing

bushings

104, 105. The opposite ends of the pivot shaft 106 project beyond the

hubs

65, 66.

Washers

107, 108 are placed one on each projecting end of the pivot shaft 106, and are secured thereto, as by welding, to tix the position of the pivot shaft 106 relatively to the

hubs

65, 66 in an axial direction. A supporting arm structure 109 is secured to the pivot shaft 106. Such supporting arm structure 109 includes a sleeve half 110, within which there is received the pivot shaft 106. Oppositely directed flanges 111 are integrally formed with the sleeve half 110. Another sleeve half 112 overlies the pivot shaft 106 and forms a cap for the sleeve half 110. The sleeve half 112 is also formed with oppositely directed integral flanges 113, which overlie and abut the anges 111. The flanges 111, 113 are bored to receive a plurality of bolts 114, by which the sleeve halves 110, 112 are secured to each other and to the pivot shaft 106, whereby the supporting arm structure 109 for the pair of plows 62 is swiugably mounted on the hubs Y65, 66. The supporting arm structure 109 includes a pair of laterally spaced arms 115, 116 which are integrally formed with the sleeve half 110. Each of the arms 115, 116 has a somewhat twisted configuration to place the ends of the arms in proper positions to mount the respective individual plows 117, 118, as best seen in FIG. 3. The individual plows 117, 118 are secured to the arms 115, 116 by a plurality of bolts 119, whereby the plows may be easily removed, if necessary, to replace worn-out plows, or to install plows of a different configuration.

The individual plows 117, 118 are carried around the axis of the shaft 54, and move over the liner 60. The plows 117, 118 are preferably made of metal, to develop the highest degree of wear resistance to the abrasion of the sand, and accordingly, are nonyieldable. Thus, the position of the plows 117, 118 relative to the liners 60 must be carefully controlled, both for the purpose of obtaining ythe optimum action of the plows, and further, to prevent damage to the liners 60. For this purpose, the sleeve half 112 is formed with an integral holder 120, that has a threaded bore 121 extending therethrough. The axis of the bore 121 is coincident with a diametral line of the shaft 54 and intersects the axis of the latter. A bolt 122 is threaded into the threaded bore 121, with the end of the bolt projecting beyond the holder and abutting the periphery of the shaft 54. By adjustment of the position of the bolt 122 in the threaded bore 121, the position of the plows 117, 118 relative to the liners 60, may be adjusted. A locking nut 123 secures the bolt 122 in adjusted position.

The' plows 170 and 171 though shaped differently from plows 117 and 118 are joined to shaft 54 in a manner similar to the fastenings described above with relation to plows 117 and 118. Therefore, a repetitious detailed description is considered unnecessary.

In the operation of the mulling apparatus as heretofore described, the sand is delivered to the feed chute 34 in a vcontinuous stream, and flows through the feed opening 44 into the cylindrical drum 20. At the same time, the mixture of water and bonding materials is delivered through the conduit 57 and the transverse discharge ports 58 into the cylindrical drum 20, to be mixed with the sand. The shaft 54 is rotated, thereby causing the several mulling wheels 89, 90, etc., and the several plows 117, 118, etc., and -175, to be moved about the axis of the shaft 54 and over the inwardly facing surface of the liners 60, this being the mulling surface. The shaft 54 is rotated at a relatively high speed whereby centrifugal force causes the mulling wheels 89, 90, etc., and the plows 117, 118, etc., and 170-175, to swing outwardly towards the inwardly facing mulling surface. Such outward swinging movement of the mulling wheels 89, 90, etc., is limited only by engagement of the wheels with theliners 60. The outwardly swinging movement of the plows 117, 118, etc. and 170-175, is limited by the setting of the adjusting bolt 122. To assure proper outward movement of all of the plows it may be necessary to add weight to the plows to increase the centrifugal force imposed by the rotation of the shaft. Naturally, other suitable means may be used tol assure the outward position of the plows during rotation even 4to the extent of fixing them in position. However, it is contemplated to be more desirable to utilize pivotable plows as shown so that should large foreign matter such as scrap metal pieces be inadvertently introduced into the muller the plows will swing out of the way should they strike the foreign matter and thereby prevent extensive damage to either the plows or liner as might be the case with fixed plows.

For the purposes of describing the operation of the apparatus, it is assumed that the muller is in the middle of its run although no sand is shown in any of the drawings. As the sand feeds into the cylindrical drum 20 and through the cylindrical drum 20, it is progressively engaged between the mulling wheels and the liners 60. Such engagement produces a progressive pressing, kneading and mixing action on the mass of sand to be engaged, whereby the sand mixed and combined with the water and bonding materials. Since the mulling

wheels

150, 151, etc. and 160, 161, etc., are free wheeling on the respective shafts 85, they rotate about their own axes as they move around the axis of the shaft 54 and over the inwardly facing mulling surface of the cylindrical drum 20. Such rotation of the mulling wheels 150-155 and 160-165 is instrumental in working the sand and properly mulling the same as aforesaid. The plows 117, 118 are arranged to follow behind the mulling

wheels

150, 151, respectively, in the direction of their movement about the axis of shaft 54. Likewise, plows 170, 171 are arranged to follow behind the mulling wheels 160-161. This arrangement is carried through the entire mulling machine for the remaining plows and wheels. Preferably, the center of the plows and the center of the wheels which each plow follows are in the same plane; however, some variation from this arrangement will still give acceptable results as long as the principle of a plow following a wheel is preserved. The mulling action of the mulling wheels results in some compacting of the sand on the mulling surface of the liners 60. The plows engage the sand that is so compacted, and scrape it from the mulling surface of the liners 60. Due to the relatively high speed rotation of the shaft 54, the plows 117, 118, 11711, 118er, 117b and 118b effectively throw the sand, dispersing and distributing the same around the inwardly facing surface of the cylindrical drum 20. Thus, there is mulling of the sand on all portions of the inwardly facing mulling surface in the cylindrical drum 20.

Each of the plows 117, 118, 117a, 118:1, 117b, and 118b is disposed at an angle, with a concave face in contact with the sand such that when the plows meet the sand, the action of the plows in addition to moving the sand about the entire interior circumference tends to move the sand in an axial or longitudinal direction towards the discharge end 33 of the mulling apparatus. The plows 170-175, however, because of the convex surface presented to the sand will in addition to moving the sand about the interior circumference direct a significant portion of the sand toward the feed end of the muller as well as toward the discharge end, thus controlling or limiting the movement of the entire charge through the muller. With plows 170-175 directing sand each way, the sand is passed back and forth by the plows, but on the whole moving more to the discharge end 33 all the time, so that there is a resultant movement of the sand through the cylindrical drum 20 towards the discharge end 33.

As a result of this construction various factors can be said to affect the rate of movement of the sand through the muller. As shown in the drawings, the angle of the plows will be one factor. Assuming that at the angle shown, a desirable rate of rotation of the muller wheels and plows is approximately 116 r.p.m., it is apparent that by altering the angle of the plows the rate of movement of the sand through the drum 20 will be changed. Accordingly, the rate of feed of the sand into the drum will require changing to correspond to the discharge rate of the sand to maintain continuity in the operation at the same thickness of sandy in the muller. Further, it will become apparent that if the angles of the plows are maintained as shown, an increase or decrease in the rotative speed of the wheels and plows will also change the rate of movement of the sand through the cylindrical drum. One additional factor which will change the rate of sand through the drum which is novel with regard to the type of action of this muller is that by holding the angle of the plows constant as shown and the rotative speed of the plows and wheels constant, the rate of movement of sand through the cylindrical drum 20 may be changed by increasing or decreasing the rate of feed of the sand into the cylindrical drum. The rate of discharge at the discharge end will change accordingly, as will the thickness of the sand within the muller.

The action of the present novel muller apparently is unique in its action on the sand. For one thing, a part of the sand during the working of the machine is apparently accelerated by the plows to a velocity sufficient to carry a large portion of the total sand in a circular movement about the entire circumference of the cylindrical shell in a layer which decreases in thickness from the intake end toward the discharge end. It appears that the sand will flow toward the discharge end at what may be called a dynamic angle of repose. It further appears that the substantial condition of agitation of the sand in the drum breaks down the tendency of the sand to retain its natural stationary angle of repose and to act as a liquid which makes the foregoing flow of the material through the muller possible. This phenomenon is supported by analogous findings from foundation and soils mechanics studies where it has been determined that shearing `strength of sand may be said to consist of two parts, the internal, frictional resistance between grains, which is a combination of rolling and sliding friction, and a second factor which is called interlocking, and where it has been noted by at least one soils mechanics expert that in sands which naturally have very loose packing any sudden occurrence of strain may lead to almost complete liquifaction, occasionally in slopes as flat as five or ten degrees, and may cause slides of large extent. In addition, the energy expended in overcoming the shear strength of sand has been found to cause an increase in volume. This perhaps explains why the ufling action of the present device is so outstanding.

The above analogy to liquid explains why a change in the feed rate of the sand without any change in the plows or wheels or rate of rotation will be a sole factor in determining the rate of movement through the mulling machine. It appears that the difference in head between the entering sand and the discharge opening plus the agitation of the sand is sufficient to move the sand along. Since increasing the feed rate of the incoming sand obviously increases the difference in head, the sand will therefore move more quickly through the muller. Another thing that will become apparent is that at the rotative speeds contemplated for this muller more sand will tend to be retained at the lower portion of the horizontal muller cylinder 20 than at the upper portions due to the effects of gravity. Thus, the sand can be visualized as a moving substantially horizontal hollow cylinder of sand with a greater wall thickness at the bottom portion than at the top portion. Moreover, due to the aforementioned dynamic angle of repose the cylinder walls will be thicker at the feed end of the muller than at the discharge end.

Another factor which appears to give improved action to the present muller is the variable action of each mulling wheel on the sand as it makes a complete circuit about the circumference of the cylindrical shell. For example, as the wheel rotates it is thrown outwardly by the centrifugal force built up as a result of the rotation. As each wheel moves upwardly toward the top of the horizontal shell 20, the wheel meets less sand for the yreasons previously brought out. Since there is less firm contact with the sand due to the force of gravity on the wheel, the wheel will rotate at a much slower speed than its synchronous speed and thereby impose a greater skidding or smearing action at this point. As the wheel moves down toward the bottom of the shell it encounters a thicker layer of sand which offers greater resistance to the wheel and thereby causes the wheel to rotate at a speed much closer to its synchronous speed. In addition, gravity which had some influence on the force imposed on the wheel throughout its circuit, will cause the wheel pressure to be greatest toward the bottom of the shell. Thus, the action of the wheel at the bottom of the shell is predominantly a pressing and mixing action.

These numerous factors in this device contribute to a mixing, smearing, pressing action which is constantly changing, and because of this variable action apparently accounts for the superior quality of the results attained therefrom.

The plows 117, 118, 117a, 118:1, 117b and 118b and 170-175, as illustrated in the drawings, are merely exemplary, and it is to be understood that other shapes may be determined for the plows, which will be found to be most satisfactory for the particular operating conditions of a given installation. It is further contemplated that fiat, straight across, scoop type plows may be found to be satisfactory. Such plows would still operate to permit the flow of sand as set out above.

During the operation of the mulling apparatus, as above described, the several mulling wheels and the several plows are swung outwardly on their respective supporting arms structures by centrifugal force to adjacent the mulling surface of the liners 60. However, when the apparatus is idle, the positions of the mulling wheels, plows, and their respective Supporting arms is determined by the force of gravity. Thus, referring to FIG. 4, in an idle condition of the apparatus the mulling wheels 61 would drop downwardly, and in order to limit such downward movement there is provided an abutment type stop 125 extending between the

hubs

65, 66. The

arms

76, 77 will contact the abutment type stop 125 and thereby limit the degree to which the mulling wheels 61 will drop in the idle condition. Similarly, there is provided an abutment type stop 126 for the plow arms, such as 115, 116 to limit the extent to which the corresponding plows 117, 118 drop away from the mulling surface under the force of gravity.

In order to improve the discharge of the sand through the discharge opening 45, there is provided a discharge flinger 128, comprising a plurality of arms 129, each of which is secured to the shaft 54, as by welding, and extends therefrom in a radial direction. The end of each arm 129 is formed with a mounting block 130, to which there is secured a blade 131 by means of a plurality of bolts 132. Thus, the blades 131 may be readily removed when it is necessary to replace the same. The discharge flinger 128 rotates with the shaft 54. This discharge flinger operates to prevent any build up of sand at the discharge end.

It is customary to maintain a constant circulation of sand in a foundry system, whereby the sand is reused. Such sand is at a considerably higher temperature when it reaches the mulling apparatus, than the temperature which is desired for the sand when it is used in the making of molds. In the mulling apparatus of this invention the hot sand may be cooled as it is being mulled. Such cooling may be accomplished by a current of cooling air being passed through the sand in a cylindrical drum asthe sand is mulled therein. In FIGS. 1 and 3 there is the representation of a blower outlet 133, which may be directed into the feed chute 34 for blowing a current of air through the sand to cool the same. As illustrated herein, the air flow is concurrent with the direction of movement of the sand. However, a countercurrent ow of air may also be used.

Referring now to FIGS. 9, 10 and 11, there is illustrated therein a modification of the invention heretofore described. In such modification, there is provided an adjustable stop means for the mulling wheels, whereby the mulling wheels may bear against the liners 60, or may be maintained in spaced relation to the same. In the embodiment of the invention illustrated in FIG. 4, the mulling wheels are moved outwardly against the mulling surface without limitation by the action of centrifugal force on said mulling wheels. In the modied embodiment of the invention there is provided means for limiting the maximum position of the mulling wheels relative to the mulling surface under the action of centrifugal force. Thus, as seen in FIG. 9, in the maximum outer position of the mulling wheels there is a gap between the periphery of the mulling wheels and the mulling surface. In some mulling operations it is found desirable to maintain such a gap, whereby the force of the mulling wheels on the sand is restricted. However, the action of these wheels is essentially the same as that described herebefore.

Referring to FIGS. 10 and 11 in which the modification is illustrated in greater detail, the sleeve half 82 has an adjusting bolt holder that is integrally formed therewith. The holder 135 is disposed above the sleeve half 82' and has a threaded bore 136, the axis of which is disposed on a diametral line of the shaft 54, and intersecting the axis of the latter. The holder 135 is offset so that the elements of the mulling apparatus will clear each other. A bolt 137 is threaded through the holder 135 and projects beyond the end thereof into engagement with the periphery of the shaft 54. Thus, by adjusting the position of the bolt 137, the maximum outer position of the mulling wheels is likewise adjusted and determined. A locking nut 138 secures the adjusting bolt 137 in its adjusted position.

The most outstanding feature of the mulling apparatus described herein is that it is continuously operative to mull sand. Thus, such mulling apparatus is compatible with a continuous foundry system, in which the molding sand is constantly circulated in the foundry system. The mulling apparatus may be set up to mull sand at a rate equal to the rate of ow or movement of the sand in the foundry system. Further, the sand which is discharged from the mulling apparatus is ready for use in making molds, in that the mulling operation by means of the mulling apparatus of this invention includes aeration of the sand, and if required, the sand may also be cooled as it is being mulled.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and applicant therefore wishes not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of the invention, what it is desired to secure by Letters Patent of the United States is:

1. A method of mulling sand to prepare such sand for the making of molds using the mulled sand comprising, adding bonding and conditioning materials to said sand, subjecting said sand and said bonding and conditioning materials to a progressive pressing, kneading and mixing action to form a homogeneous mixture of the sand and the materials in which the grains of the sand are substantially coated with the materials, simultaneously mixing and agitating the sand mixture to a degree sufficient to eliminate the shear strength of the sand and thereby to cause it to ow substantially as a liquid, continuously References Cited feeding sucient additional sand and materials to supply UNITED STATES PATENTS a pressure head to push the sand mixture along, and continuously removing the mulled sand mixture at substan- 1,706,417 3/1929 SITIPSOII 241-98 tially the same rate as the feed rate of the sand and the 5 2,264,610 12/ 1941 Beardsley 259-147 materials. 3,162,428 12/ 1964 Lodige 259-9 2. A method of mulling sand to prepare such sand for 3,204,302 9/ 1965 McIlvaine 259-151 the making of molds using the mulled sand, as recited in claim 1, comprising, directing air in contiguity with the ROBERT W. JENKINS, Primary Examiner. moving mixture of sand and materials. lo

Claims

1. A METHOD OF MULLING SAND TO PREPARE SAND FOR THE MAKING OF MOLDS USING THE MULLED SAND COMPRISING, ADDING BONDING AND CONDITIONING MATERIALS TO SAID SAND, SUBJECTING SAID SAND AND SAID BONDING AND CONDITIONING MATERIALS TO A PROGRESSIVE PRESSING, KNEADING AND MIXING ACTION TO FORM A HOMOGENEOUS MIXTURE OF THE SAND AND THE MATERIALS IN WHICH THE GRAINS OF THE SAND ARE SUBSTANTIALLY COATED WITH THE MATERIALS, SIMULTANEOUSLY MIXING AND AGITATING THE SAND MIXTURE TO A DEGREE SUFFICIENT TO ELIMINATE THE SHEAR STRENGTH OF THE SAND AND THEREBY TO CAUSE IT TO FLOW SUBSTANTIALLY AS A LIQUID, CONTINUOUSLY FEEDING SUFFICIENT ADDITIONAL SAND AND MATERIALS TO SUPPLY A PRESSURE HEAD TO PUSH THE SAND MIXTURE ALONG, AND CONTINUOUSLY REMOVING THE MULLED SAND MIXTURE AT SUBSTANTIALLY THE SAME RATE AS THE FEED RATE OF THE SAND AND THE MATERIALS.