US3481547A - Continuous mulling apparatus - Google Patents

Description

Dec. 2, 1969 K. H. ANDRAE 3,481,547

CONTINUOUS MULLING APPARATUS Filed June 26, 1967 2 Sheets-Sheet 1 Mas/v70 KARL H.ANDRAE,

BYM

H'TToR/vEX,

Dec. 2, 1969 K. H. ANDRAE. 3,481,547

CONTINUOUS MULLING APPARATUS Filed June 26, 1967 2 Sheets-Sheet 2 //YVEN7'O/?; KARL H. ANDRAE,

ATTOENEX United States Patent U.S. Cl. 241-156 Claims ABSTRACT OF THE DISCLOSURE Continuous mulling apparatus in which there is a receptacle through which the material flows as it is mulled in the receptacle. There is a mulling assembly at each of a plurality of successive positions in the receptacle to mull the material. The mulling assembly has means to interrupt the flow of the material in order to retain material at a position in the receptacle for mulling, and such interrupting means includes deflector means by which at least a part of the material may be impelled in either the downstream or the upstream direction of flow to control the retention time of the material in the receptacle.

The instant invention relates to the mulling of materials, for example as is practiced in foundry operations in respect to the preparation of sand for making molds, and more particularly, to improvements in a continuous mulling apparatus.

This invention has application to the treatment of materials by mulling, for example the mulling of sand in a foundry to place the same in suitable condition for use in making molds in metal casting operations. The mulling of the sand may involve new sand which has not previously been used in making 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 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, it is desired that these ingredients be uniformly combined with the mass of sand, and in an ideal operation each grain of sand is completely 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 pressed, kneaded and mixed until the added ingredients are uniformly dispersed in the mass of sand, and the grains of sand are each coated with the bonding materials. In mulling operations, in which recirculated sand is being operated upon, such sand is usually very hot as the result of being in contact with hot molten metal, and is far hotter than is desired for the mulling operation or for the formation of molds. 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, in addition to the tempering water that is added. 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 loose, uniform condition, in which it may be readily and uniformly packed around a pattern in the process of making a mold with such sand.

It is an object of the instant invention to provide an improved continuous apparatus for the preparation of materials by mulling, for example, sand to be used in the making of molds.

3,481,547 Patented Dec. 2, 1969 It is another object of the instant invention to provide an improved apparatus for the mulling of materials, which is continuous in its operation and through which the materials continuously flow, such flow of the materials being retarded to provide a retention time of the materials in the apparatus of sufficient length as to effectively mull the same.

It is another object of the instant invention to provide animproved apparatus for the mulling of materials, in which the material continuously flows through the apparatus and there is provided means by which the retention time of the material may be selectively adjusted and controlled.

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

In the drawings:

FIG. 1 is a longitudinal, elevational view of the continuous muller constructed in accordance with this invention, partially in section;

FIG. 2 is a transverse sectional view of the continuous muller, taken on the line 22 in FIG. 1;

FIG. 3 is a partial transverse sectional view of the continuous muller, taken on the line 33 in FIG. 2;

FIG. 4 is a partial view of a typical mulling assembly, taken on the line 4-4 in FIG. 3;

FIG. 5 is a view of an alternate form of the mulling assembly that is illustrated in FIG. 4; and

FIG. 6 is a partial transverse sectional view of the continuous muller, taken on the line 6-6 in FIG. 1.

Referring to the drawings, the continuous muller, which is illustrated therein, is the same type and class of apparatus as the continuous muller which is described in my copending application Ser. No. 333,936, filed Dec. 27, 1963, now Patent No. 3,430,874, for Continuous Muller and Method of Mulling, and comprises a cylindrical drumlike receptacle 11 placed on a substantially horizontal axis, whereby the cylindrical receptacle 11 is disposed in a lateral position extending along its axis. The receptacle 11 is supported on feet 12, 13 that are placed at opposite ends of the receptacle 11 for securing it to a supporting base 14, as by a plurality of bolts.

The receptacle 11 includes a cylindrical shell 15. The feed or upstream end of the cylindrical shell 15 is closed -by an end wall 16, and the discharge or downstream end of the cylindrical shell 15 is closed by a similar end wall 17. A plurality of longitudinally extending ribs 18 are secured to the outer wall of the cylindrical shell 15 to rigidify the receptacle 11, as best seen in FIG. 2. The ribs 18 preferably are radially disposed on the cylindrical shell 15.

The receptacle 11 is provided with an opening that extends the full length thereof in an upper quadrant of the cylindrical shell 15, as best seen in FIG. 2. The opening is illustrated as being of lesser arcuate length than however, it will be understood that the size of the opening is governed by the need for reaching inside the receptacle 11 for maintenance of the various elements of the continuous muller that are contained therein. The opening is closed by a cover 20 which forms a continuation of the cylindrical shell 15, and completes the cylindrical shell 15 when the cover 20' is closed, as seen in FIG. 2. The cover 20 is connected to the receptacle 11 at each end thereof by a hinge 21 on a longitudinally extending axis, whereby the cover 20' may be readily raised to its open position.

Referring to FIG. 1, there is a shaft 22 that extends through the receptacle 11, with its axis coincident with the axis of the cylindrical shell 15. The opposite ends of the shaft 22 are rotatably supported on the end walls 16, 17 in like manner at each end wall. The end wall 16 has a centrally disposed circular opening 23, and the shaft 22 extends through the opening 23. A disc-like retainer 24 is placed in the opening 23, and the latter is filled with a felt packing seal 25 that fills the opening 23 and forms a seal against the periphery of the shaft 22. The felt seal 25 is held in the opening 23 by a pair of rectangular retainer plates 26, 27, as se n in FIG. 2. The packing 25 is compressed in the end wall opening 23 between the retainer 24 and the plates 26, 27, to fill the opening 23 and to seal the shaft 22 therein.

The shaft 22 projects beyond the end wall 16 and is formed with a reduced diameter end 28 to be rotatably supported in a flange roller bearing 29. A ring 30 is disposed between the fiange roller bearing 29 and the end wall 16. The flange roll r bearing 29 is secured to the ring 30 and to the end wall 16 by a plurality of bolts 31, or the like, as seen at the left in FIG. 1. The ring 30 is partially cut away to provide an opening 32 at the bottom thereof, which is of substantial size. Any material which might get past the felt seal 25 will drop to the bottom of the ring 30 and out through the opening 32, and thereby such material is prevented from working its way into the flange roller b aring 29. A shaft guard 33 is installed on the non-driven end of the continuous muller. Suitable driving means is connected to one end of the shaft 22, at the left hand end as viewed in FIG. 1, to rotate the latter. The shaft 22 is rotatably supported on the end wall 17 in the same manner as has been described with respect to the end wall 16.

The end wall 16 has a feed opening 35 disposed at one side of the shaft 22, and at the opposite side there is a rectangular opening 36 for the supply or exhaust of a current of air that may flow through the muller receptacle 11. A feed chute 37 terminates at its bottom in an opening that is aligned with and connects with the feed opening 35 for the discharge of sand into the muller receptacle 11. An air duct 38 connects to the rectangular opening 36 for the flow of air through the continuous muller, which may be concurrent with the direction of feed of material through the muller, or countercurrent thereto.

The sand is received in the muller receptacle 11 at the feed or upstream end and then flows in a downstream direction through the receptacle 11 to the downstream or discharge end thereof, at which there is a discharge section 40 from which the sand discharges through the discharge chute 41. As the sand flows through the receptacle 11, it is successively mulled by a plurality of successive mulling assemblies 42a, 42b, 42c, 42d, 42e, 42 42g, 42h, all of which are identical, except for the mulling assembly 42a which has an additional element, as will be described hereinafter. In the interest of clarity, FIG. 1 includes a complete illustration of only the mulling assemblies 42a, 42b, which are the first and second mulling assemblies in the direction of flow from upstream to downstream. The remaining mulling assemblies 42c-h are merely represented by an outline of the mulling wheels and plows thereof. The description of the mulling assemblies 42a, 42b is applicable to the mulling assemblies 42c-h, except as to the one added element of the mulling assembly 42a, as will be specifically mentioned hereinafter.

The several mulling assemblies 42ah are secur d to the shaft 22 to be moved thereby about the axis of the shaft 22. The mulling assemblies 42a-h are disposed at equally spaced positions along the shaft 22 between the feed or upstream end of the muller receptacle 11 and the discharge section 40. As the sand flows through the muller receptacle 11 from the feed or upstream end thereof towards the discharge section 40 at the discharge or downstream end of the muller receptacle 11, the mulling assemblies 42ah successively operate on and mull the sand. The successive positions of the several mulling assemblies 42a-h along the shaft 22 are apparent in FIG. 1, and are further indicated by the letters a-h at the bottom of FIG. 1, identifying and locating the several successive mulling positions along the length of the muller receptacle 11.

For each mulling assembly 42a-h there is secured to the shaft 22 a partial hub 43, as best seen in FIG. 2. The hub 43 extends through an angle somewhat greater than 180, sufiicient to receive three bolts at positions spaced 90 relativ ly to each other. Each partial hub 43 is firmly secured to the shaft 22, as by welding, for mounting a mulling assembly 42.

Referring to FIG. 2, there is illustrated therein the mulling assembly 4241, which is typical of the construction of the several mulling assemblies 42a-h, with the exception that it includes an additional element. The mulling assembly 42a is constructed on a frame 44 that comprises a center hub portion 45 formed with an arcuate recess 46 that is open along a diametral line, whereby the frame 44 and the mulling assembly 42a may be placed over the shaft 22. The hub portion 45 of the frame 44, and the partial hub 43, are each formed with three apertures, which are aligned with each other to receive three bolts 47, by which the frame 44 is secured to the partial hub 43 and is mounted on the shaft 22, thereby to secure the entire mulling assembly 42a to the shaft 22.

The frame 44 has a first mounting arm 48 and a sec ond mounting arm 49, which are formed as extensions of the frame hub portion 45, and extend from opposite sides of the hub portion 45, The outer end of the first mounting arm 48 has an integral sleeve 50 for receiving the shaft 51 of a hub 52. A supporting lever 54 is fixedly secured to the hub 52 by a plurality of bolts 56, of which there may be three. The supporting lever 54 has the form of a crank and comprises an outer arm 57 and an inner arm 58. At the end of the outer arm 57 there is an integral axle 59 with its axis parallel to the axis of the shaft 22. A mulling wheel 60 is rotatably mounted on the axle 59. The mulling wheel 60 has a tire 61 that is formed of rubber, or like yieldable material.

The outer arm 57 supports a dam 62, the latter being a plate member that is laterally disposed with respect to the axis of the shaft 22. The hub 52 has a central pin 63 projecting therefrom, and the dam 62 has an aperture 64 of the same size as the pin 63, to receive the latter. The dam 62 includes a first arcuate slot 65 and a second arcuate slot 66, through which there extend bolts 67, 68, respectively, that are threaded into the outer arm 57 to secure the dam 62 on and against the outer arm 57, and the position of the dam 62 can be adjusted about the axis of the pin 63. The outer edge 69 of the dam 62 is formed on a circular are that is concentric with the cylindrical wall of the receptacle 11. By adjustment of the position of the dam 62, the spacing between its outer edge 69 and the wall of the cylindrical receptacle 11 may be adjusted for a purpose that will be explained hereinafter.

At the leading edge 70 of the dam 62 there is a cut 71 into the dam 62 to form a leading edge vane 72 between the cut 71 and the outer edge 69 of the dam 62. The length of the cut 71 determines the circumferential length of the vane 72. At the trailing edge 73 of the dam 62 there is another similar cut 74 into the dam 62 to form a trailing edge vane 75. As illustrated in the drawings the leading edge and trailing edge cuts 71, 74 are alike so that the vanes 72, 75 that are formed by such cuts are also alike. However, the vanes 72, 75 need not be exactly alike, which is to say that one vane may be cut deeper into the dam 62 in the circumferential direction than the other vane, and one vane may be higher in the radial direction of the cylindrical receptacle 11 than the other vane.

The leading edge vane 72 and the trailing edge vane 75 are bent in opposite directions out of the plane of the dam 62 as best seen in FIG. 4. The leading edge vane 72 is bent in the upstream axial direction and the trailing edge vane 75 is bent in the downstream axial di rection, so that both vanes are aimed in the same direction. As the dam 62 is moved around the axis of the shaft 22, the vanes 72, 75 work as deflectors on the sand that is disposed on the inner surface of the cylindrical receptacle, and impel a part of the sand in the downstream direction. The quantity of sand that is so impelled is determined by the extent to which the leading edge vane and the trailing edge vane are bent out of the plane of the dam. The quantity of sand that is impelled in the downstream direction may be increased by increasing the angles of the vanes relative to the plane of the dam.

The leading edge vane 72a may be bent in the downstream direction and the trailing edge vane 75a may be bent in the upstream direction, as seen in FIG. 5. In such alternative construction the vanes 72a, 75a are aimed upstream and are operative to deflect and to impel the sand in the upstream direction. Again, the quantity of sand that is deflected is determined by the angle of the vanes 72a, 75a relatively to the plane of the dam 62, and a greater angle of the vanes 72a, 75a will deflect greater quantities of sand. The inner arm 58 extends from the hub 52 to a position adjacent the shaft 22. At the end of the inner arm 58 there is an eccentric disc 76 which abuts the shaft 22. A bolt 77 releasably secures the eccentric disc 76 to the inner arm 58, whereby the position of the eccentric disc 76 may be adjusted, thereby varying the spacing between the end of the inner arm 58 and the shaft 22 when the eccentric disc 76 is in contact with the shaft 22. The disposition of the outer arm 57 is adjusted accordingly, with the ultimate effect of adjusting the outermost position of the mulling wheel 60 relatively to the wall of the cylindrical receptacle 11.

The second mounting arm 49 of the mulling assembly frame 44 has three pairs of apertures 78, 79, 80 which are spaced from each other and are disposed in two circular arcs that are concentric. A plow 81 is mounted on the second mounting arm 49. The plow 81 has an arm 82 with a bifurcated end 83 that has a pair of apertures which are spaced apart the same distance as the individual apertures of each pair of apertures 78, 79, 80. The second mounting arm 49 is received within the bifurcatedend 83 of the plow arm 82 and is releasably secured thereto by a pair of bolts 84 extending through the apertures in the bifurcated end 83 of the plow arm 82 and one pair of the apertures 78, 79, 80, which is aligned therewithfThe plow arm 82 extends toward-the cylindrical shell of the receptacle 11 and-terminates in an integral foot 85 that extends laterally to opposite sides of the arm 82. The foot 85 has a flat surface facing inwardly of the receptacle shell 15, and this flat surface is inclined with respect to a tangent to the receptacle shell 15. A plow blade 86 is releasably secured to the foot 85 by a pair of bolts 87 disposed one at each side of the arm 82. The leading edge of the plow blade 86 is disposed closely adjacent to the inner surface of the receptacle shell 15 and extends-therefrom at the same angle of inclinaiton as the foot 85.

The inclination of the plow blade 86 with respect to a tangent to the cylindrical shell 15 may be adjusted by selection of the pair of apertures 78, 79, 80 to which the plow 81 is secured. The pairs of apertures 78, 79, 80 are disposed in concentric circular arcs having a center ap-' proximately on the leading edge of the plow blade 86, whereby in any position of adjustment of inclination of the plow blade 86, the spacing between the leading edge of the plow blade 86 and the inner surface of the receptacle shell 15 remains substantially the same.

The inner cylindrical surface of the receptacle 11 provides the mulling'surface on which the sand is mulled as it flows through the receptacle 11 in a longitudinal direction. There is a liner 90 that is formed of rubber, or like yieldable material to form a suitable surface on the receptacle shell 15 for mulling the sand.

Each mulling assembly 42a-h is operative to mull the sand in the receptacle 11. The mulling, as such, is accomplished by the several mulling wheels 60 of the mulling assemblies 42a-h and the liner 90. The mulling action, comprising the pressing, kneading and mixing of the sand, takes place between the mulling wheels 60 and the liner 90. The sand is dispersed on the liner 90 about the axis of the shaft 22, and the mulling wheels 60 engage the sand that is so dispersed on the liner 90, and there is a pressing, kneading and mixing action of the mulling wheels 60 on the sand to accomplish the mulling of the sand. The sand as it flows longitudinally through the receptacle 15, and is dispersed therein, is highly abrasive in its action, on the elements of the apparatus, and particularly so with respect to the elements which are operative to work the sand. Thus, each mulling wheel 60 is provided with the tire 61 made of yieldable material, and likewise, the liner 90 includes the sheet 91 of yieldable material to form the mulling surface, which are more resistant to the wearing, abrasive action of the sand than would be the case with non-yieldable materials, for example, metal. The operation of the continuous muller will be described in greater detail hereinafter.

The construction of the mulling assembly 42a is typical of each of the mulling assemblies 42b-h, each of which includes all the elements thereof which have been described heretofore; however, the mulling assembly 42a includes an additional element which is the intake accelerating plow 92, as best seen in FIGS. 1 and 2. The plow 92 has a plow blade 96 which is disposed substantially parallel to the axis of the shaft 22, and is in front of the mulling wheel 60 to lead the latter in the direction of movement thereof around the axis of the shaft 22, this being in a clockwise direction, as viewed in FIG. 2. The intake accelerating plow 92 meets the sand as it initially flows into the receptacle 11, and gives such sand an initial acceleration or movement, and in effect disperses the sand to prevent it from piling up excessively in front of the mulling wheel 60 of the first mulling assembly 42a. By reason of the gap between the plow blade 96 and the liner 90, a substantial amount of sand remains ahead of the mulling wheel 60 to be acted upon thereby.

At the discharge section 40 of the receptacle 11 there is provided a radially extending sweeper blade 97, as best seen in FIGS 1 and 6. Near the end wall 17, a partial hub 98 is secured to the shaft 22, as by welding. The partial hub 98 has the same configuration as the several partial hubs 43, for the mulling assemblies 42a-h. The The sweeper blade 97 has a hub portion 99 that is placed on the shaft 22 adjacent the partial hub 98, and the sweeper blade 97 is secured to the partial hub 98 by a plurality of bolts 100, which may be three in number. The sweeper blade 97 is formed as a planar element disposed in a plane that is placed laterally with respect to the shaft 22. The sweeper blade 97 rotates with the shaft 22 in front of the end wall 17. As the sand flows downstream and reaches the discharge section 40 it would normally have a tendency to adhere to the end wall 17 and to accumulate on the same. However, the rotating sweeper blade 97 prevents such accumulation of the sand, and accordingly, the sand continuously discharges through the discharge chute 41 at the same rate as the rate of movement of the sand into and through the receptacle 11.

The operation of the continuous muller will now be described in more detail. The sand flows into the receptacle 11 from the feed chute 37 and through the feed opening 35 at the feed or upstream end thereof. As the sand enters the receptacle 11, it is met by the intake accelerating plow 92 which starts the sand in movement around the axis of the shaft 22 and prevents an excessive accumulation of sand in front of the mulling wheel 60 of the mulling assembly 42a. The intake accelerating plow 92 impels the sand in a lateral direction with respect to the axis of the shaft 22. However, the sand also has a tendency to fan out upstream and downstream from the opposite side edges of the plow blade 96.

The mulling wheel 60 of the mulling assembly 42a follows closely behind the intake accelerating plow 92, the

mulling assembly 42a being moved in a clockwise direc tion by the shaft 22, as viewed in FIG. 2. The dam 62 extends to almost the axis of the mulling wheel 60. Behind the dam 62 and ahead of the mulling wheel 60 there is retained sand that is engaged by the mulling wheel 60. Thus, the association of the intake accelerating plow blade 96 with the dam 62 and the end wall 16 assures that while excessive accumulations of sand are removed from the path of the mulling wheel 60, nevertheless a substantial amount of sand remains in the path of the mulling wheel 60, to be engaged by the latter and to be pressed, kneaded and mixed thereby on the mulling surface of the liner 90.

While the darn 62 retains sand in front of the mulling wheel 60 to be mulled by the latter, this is moderated by the vanes 72, 75 at the leading edge and at the trailing edge, respectively, of the dam 62. The vanes 72, 75 are aimed in the downstream direction to form deflectors on the dam 62 that impel at least a part of the sand in the axial downstream direction. This reduces the amount of sand that is retained behind the dam 62, and the extent of such reduction depends on the angles between the vanes 72, 75 and the plane of the dam 62. The overall effect of reducing the amount of sand that is retained behind the dam 62 is to reduce the total retention time of the sand in the continuous muller by causing the sand to move through the muller at a greater rate of flow. When the vanes 72, 75 are bent in the opposite directions so as to be aimed in the upstream direction, the effect is for the vanes 72, 75 to impel at least a part of the sand in the upstream direction with the result of increasing the amount of sand that is retained behind the dam 62. This reduces the rate of flow of the sand through the continu ous muller and increases the retention time of the sand in the continuous muller.

The shaft 22 is rotated at a relatively high rate of speed, sufficient to cause the mulling wheel 60 to be moved outwardly towards the mulling surface of the liner 90 by centrifugal force. The limit of the outward movement of the mulling wheel 60 in response to the action of centrifugal force is determined by the inner arm 58 and the setting of the eccentric disc 76. The mulling action is found to be most effective when there is provided a gap between the peripheral of the mulling wheel 60 and the mulling surface of the liner 90, for example as seen in FIGS. 2 and 3. The maintenance of such a gap prevents the grains of sand from being crushed, which would otherwise occur, and the action of the mulling wheel 60 on the sand is then, in true effect, only a pressing, kneading and mixing action, which is the requisite action for properly combining the sand with the bonding ingredients. The optimum gap between the periphery of the mulling wheel 60 and the mulling surface of the liner 90 may be different for different sands, different combinations of sand and bonding ingredients, and different operating conditions. Accordingly, the eccentric disc 76 may be set to provide the appropriate gap between the mulling wheel 60 and the mulling surface of the liner 90. The eccentric disc 76 also provides an adjustment for wear of the mulling wheel tire 61. As such tire 61 wears down, the gap increases and by resetting the eccentric disc 76 the gap may be closed and restored to its proper dimension.

As the mulling wheel 60 moves around the axis of the shaft 22 and over the mulling surface of the liner 90 to press, knead and mix the sand, it also packs the sand against the mulling surface. Such packed sand is removed from the mulling surface of the liner 90 by the plow 81 that follows behind the mulling wheel 60 in the direction of movement oft he mulling assembly 42a around the axis of the shaft 22. The plow blade 86 has its leading edge disposed closely adjacent to hte mulling surface of the liner 90, with sufiicient clearance being provided to prevent the pow blade 86 from damaging the liner 90. The plow blade 86 engages the sand that is packed on the mulling surface, to remove such sand therefrom by a scraping action. By reason of the speed of the plow 81 over the mulling surface of the liner 90, and the selected angle of the plow blade 86 with a tangent to the mulling surface, the engagement of the plow blade 86 with the sand causes the latter to be impelled in a lateral direction with respect to the axis of the shaft 22, and about the axis of the shaft 22 over the mulling surface, whereby such sand is broken up and is dispersed in the receptacle 11. The sand fans out in an upstream and a downstream direction from the plow blade 86, as an incident to being impelled in a lateral direction. In order not to impede or interfere with the impulsion and dispersion of the sand by the plow blade 86, the plow 81 is spaced a suflicient distance behind the mulling wheel such that the sand effectively clears the mulling wheel 80 as it is impelled and dispersed by the plow 81.

It is a concomitant of the impelling action of the plow 81 on the sand that the sand is distributed around the circumference of the receptacle 11 and is substantially uniformly distributed over the mulling surface of the liner 90 throughout the circumference of the latter. Thus, the sand is mulled on the mulling surface of the liner 90 between it and the mulling wheels 80 throughout the circumference of the cylindrical mulling surface.

As the sand is impelled laterally, it fans out from the plow blade 86 in upstream and downstream directions. However, the sand which fans out from the plow blade 86 in an upstream direction meets greater resistance to such movement than does the sand which fans out in a downstream direction, by reason of the fact that additional sand is continuously being delivered at the upstream end of the receptacle 11, while sand is continuously discharging from the discharge section 40 at the downstream end of the receptacle 11. Thus, there is a pressure head condition in the receptacle 11, whereby the sand flows in a stream through the receptacle 11 in a longitudinal direction from the feed or upstream end to the discharge or downstream end thereof, rather than being positively fed through the receptacle 11. In this manner, a given portion of sand flows longitudinally to the successive mulling position a-h along the length of the muller receptacle 11, to be successively mulled by the respective mulling assemblies 42a-h. The plows 81 do not act in any manner to positively feed the sand in a longitudinal direction as do plows that are sharply angled or inclined with respect to the longitudinal axis. The plows 81 are operative to put the sand in motion and to create a dynamic condition of the sand, whereby the pressure head as above described is effective to produce a true downstream flow of the sand in a longitudinal direction through the receptacle 11.

As clearly seen in FIG. 1, the mulling assemblies 42a-h are disposed at the successive positions a-h along the shaft 22, which positions are equally spaced. Thus, a given mass of sand is successively mulled by the mulling assemblies 32ah as it flows longitudinally through the muller receptacle 11. The successive mulling assemblies 42a-h have a particular angular disposition one relatively to another, which is that each mulling assembly 42 trails, or is disposed behind the preceding mulling assembly 42 in the direction of rotation thereof about the axis of the shaft 22. In the preferred embodiment of the invention disclosed herein, the angle between one mulling assembly 42 and a successive mulling assembly 42 is less than so that when viewed along the shaft 22 the successive mulling assemblies 42a-h have the appearance of being disposed along a helix.

The relative angular disposition of one mulling assembly with respect to the preceding mulling assembly is best illustrated in FIG. 2, wherein the mulling assembly 42a is illustrated in solid lines, and certain elements of mulling assembly 42b are illustrated in phantom lines; the latter are identified as the mulling wheel 60b, the darn 62b and the plow 81b. The plow blade 86 of the mulling assembly 42a is disposed somewhat in alignment in a longitudinal direction with the leading edge of the dam 62b. The mulling wheel 60b follows behind the dam 62b, although it overlaps the dam 62b, and the plow 81b is spaced :1 distance behind the mulling wheel 60b to follow the latter. As the plow blade 86 of the mulling assembly 42a scrapes the sand from the mulling surface and disperses the sand about the axis of the shaft 22, the sand flows downstream. However, the dam 62b of the successive mulling assembly 42b, to some extent, overlaps the plow blade 86, and although spaced downstream thereof, in effect, it follows the plow blade 86. Thus, as the sand fiows downstream by reason of being put in motion and dispersed over the mulling surface about the axis of the shaft 22, the darn 62b is interposed in the line of flow of the sand to momentarily interrupt such flow, whereby the dam 62b causes a mass of sand to accumulate in front of the mulling wheel 60b. As the mulling wheel 60]; fol- *lows the dam 62b in the clockwise movement thereof, it works its way through the mass of sand that is momentarily accumulated behind the dam 62b and in front of the mulling wheel 60b. Thus, in effect, the dam 62b functions to collect the sand to be worked by the mulling wheel 60b. The working or mulling of the sand is enhanced by the fact that there is the accumulation of sand behind the dam 62b, in that there is an augmented movement of the sand particles relatively to each other, which improves the pressing, kneading and mixing action on the sand by which it is combined with the bonding ingredients, and to coat the sand particles with such bonding ingredients.

As the mulling wheel 60 moves around the axis of the shaft 22, each mulling wheel 60 also rotates about its own axis. The mulling wheels 60 do not rotate on the mulling surface of the receptacle liner 90. Rather, the mulling wheels 60 engage the sand on the mulling surface of the liner 90 and rotate relatively to the mulling surface. At all times, the mulling wheels 60 are thrust outwardly by the centrifugal force acting on the same, so that the mulling wheels 60 effectively press the sand between the peripheries of the mulling wheels 60 and the mulling surface of the receptacle liner 90. As the mulling wheels 60 thus work their way through the sand that is dispersed on the mulling surface, all the while rotating about their own axes, the mulling wheels 60 are effectively pressing, kneading and mixing the particles of the sand, whereby there is ultimately produced a complete homogeneous combination of the sand with the bonding ingredients, in which the individual grains of the sand are coated with the bonding ingredients.

There is a gap between the arcuate outer edge 69 of the dam 62 and the mulling surface of the liner 90. This gap can be adjusted by means of the slots 65, 66 and the bolts 67, '68. An increased gap will have the effect of permiting more sand to flow downstream through the gap and past the dam 62, while narrowing the gap has the opposite effect. The ultimate effect of such adjustment is to adjust the retention time of the sand in the receptacle 11, which in turn affects the quality of the mulling action. Adjustment of the position of the darn 62 is also required in order that it may be properly positioned in accordance with the selective positioning of the mulling wheel '60 relatively to the mulling surface, by means of the eccentric disc 76, as previously described.

The operation as described with respect to the mulling assemblies 42a, 42b, repeats itself downstream as to the successive mulling assemblies 42c-h. The total effect of the operation is that the sand continuously flows through the muller receptacle 11 towards the discharge section 40; however, such flow is momentarily interrupted as the respective dams 62 move about the axis of the shaft 22. Such interruptions of the downstream flow of the sand merely restrain the continuous flow of a portion of the sand in order to enhance the mulling of the sand. The effect of the operation of the dams 62 is to reduce the effective or overall rate of flow of the stream of sand through the receptacle 11, so that the retention time of the sand in the receptacle 11 is sufiicient for effective mulling of the sand, as well as to produce an accumulation of sand in front of the mulling wheels 60 for effective mulling action. The foregoing operation of the dams 62 to interrupt the flow of the sand and to retain the sand is moderated by the vanes 72, 75 at the leading and trailing edges, respectively, of the dams 62. The vanes 72, 75 may be utilized to increase or to decrease the retention time of the sand, deepnding upon the direction of the vanes, whether they are aimed upstream or downstream, as has been described above.

It is believed that during the operation of the mulling apparatus the sand is distributed on the mulling surface of the liner in a cylinder from the upstream end to the discharge section 40 at the downstream end of the receptacle 11. It appears that such cylinder diverges 1nternally towards the discharge section 40, so that, 1n effect, there is a down-hill condition in the receptacle 11. Since the sand is always maintained in a dynamic condition of movement in the receptacle 11 by the action of the plows 81 dispersing the sand over the mulling surface, the sand readily flows downstream under the force of the pressure head that exists by reason of the sand being continuously fed in at the upstream end of the receptacle 11 and discharged at the discharge section 40.

The improved continuous mulling apparatus described herein provides a means whereby the material flows continuously in a stream through the apparatus. Such flow is interrupted or restrained from time to time for accumulating a quantity of material to be mulled. However, there is no disturbance of the overall continuous flowing condition of the material from the upstream end of the apparatus to the downstream end of the apparatus. The rate of flow of material through the mulling apparatus can be controlled and adjusted to the desired rate of flow, which effectively controls the retention time of the material in the apparatus. The material is dispersed about the axis of the mulling apparatus in a lateral direction to distribute the material on the mulling surface, and is maintained in a dynamic condition for the downstream flow of the material through the apparatus, which is required for continuous operation. It is an inherent feature of the mulling operation disclosed herein that the material is very effectively aerated by reason of its dispersion in the apparatus, which causes the material to be broken up so that when ultimately discharged it is in true granular form.

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. Apparatus for continuously mulling material comprising, a receptacle disposed on a laterally extending axis, said receptacle extending along said axis to define a path of flow for material through the receptacle in a longitudinal direction from one end of the receptacle to the other end of the receptacle, said receptacle comprising a wall having an inwardly facing mulling surface on which the material is to be mulled, said mulling surface being disposed about said axis, mulling means in said receptacle disposed at successive positions along said axis to successively mull the material as it flows through the receptacle, said mulling means being movable about said axis to mull the material between the mulling means and the mulling surface, and means for interrupting the flow of material to confine material in front of a mulling means to be mulled by the mulling means as it moves about the axis, and said interrupting means including deflecting means to impel the material in the axial direction of said receptacle to control the retention time of the material in the receptacle.

2. Apparatus for continuously mulling material as recited in claim 1, in which said interrupting means comprises a dam which is directed laterally with respect to said receptacle axis in the path of flow of the material to interrupt the flow of material, and said deflecting means comprises a deflector that is integral with said dam and is directed in the axial direction of said receptacle.

3. Apparatus for continuously mulling material as recited in claim 1, in which said mulling means comprises mulling wheels, means for moving said mulling wheels about said axis and over said mulling surface to mull the material between the mulling wheels and the mulling surface, said interrupting means comprises a dam which is directed laterally with respect to said receptacle axis in the path of flow of the material to interrupt the flow of material, said dam being disposed ahead of a mulling wheel to lead such mulling wheel, and said deflecting means comprises a leading portion of said dam that is directed in the axial direction of said receptacle.

4. Apparatus for continuously mulling material as recited in claim 1, in which said mulling means comprises mulling wheels, means for moving said mulling wheels about said axis and over said mulling surface to mull the material between the mulling wheels and the mulling surface, said interrupting means comprises a darn which is directed laterally with respect to said receptacle axis in the path of flow of the material to interrupt the flow of material, said dam being disposed ahead of a mulling wheel to lead such mulling wheel, and said deflecting means comprises a trailing portion of said dam that is directed in the axial direction of said receptacle.

5. Apparatus for continuously mulling material as recited in claim 1, in which said mulling means comprises mulling wheels, means for moving said mulling wheels about said axis and over saidmulling surface to mull the material between the mulling wheels and the mulling surface, said interrupting means comprises a dam which is directed laterally with respect to said receptacle axis in the path of flow of the material to interrupt the flow of material, said dam being disposed ahead of a mulling wheel to lead such mulling wheel, and said deflecting means comprises a leading portion of said dam and a trailing portion of said dam that are bent from the dam in the axial direction of said receptacle.

6. Apparatus for continuously mulling material as recited in claim 5, in which said bent portions of the dam are disposed adjacent the mulling surface of said receptacle.

7. Apparatus for continuously mulling material comprising, a receptacle disposed on a laterally extending axis, said receptacle extending along said axis to define a path of flow for material through the receptacle in a. longitudinal direction from one end of the receptacle to the other end of the receptacle, said receptacle comprising a wall having an inwardly facing mulling surface on which the material is to be mulled, said mulling surface being disposed about said axis, mulling wheels in said receptacle disposed at successive positions along said axis to successively mull the material as it flows through the receptacle, a dam disposed ahead of each mulling wheel to lead the mulling wheel as it moves about the axis, said dam being directed laterally with respect to said axis in the path of flow of the material to interrupt the flow of material and to confine material in front of a mulling wheel to be mulled by the mulling wheel, at least one of said dams including a deflector directed in the direction of a mulling wheel at a successive position in the receptacle to impel at least a portion of said material toward the successive mulling wheel to control the retention time of the material in the receptacle, and a plow following behind each mulling wheel to scrape material from the mulling surface and to disperse the material in the receptacle about the axis and over the mulling surface, said plow extending longitudinally in the receptacle and being disposed adjacent the mulling surface.

8. Apparatus for continuously mulling material comprising, a receptacle disposed on a laterally extending axis, said receptacle extending along said axis to define a path of flow for material through the receptacle in a longitudinal direction from one end of the receptacle to the other end of the receptacle, said receptacle comprising a Wall having an inwardly facing mulling surface on which the material is to be mulled, said mulling surface being disposed about said axis, mulling wheels in said receptacle disposed at successive positions along said axis to successively mull the material as it flows through the receptacle, a dam disposed ahead of each mulling wheel to lead the mulling wheel as it moves about the axis, said dam being directed laterally with respect to said axis in the path of flow of the material to interrupt the flow of material and to confine material in front of a mulling wheel to be mulled by the mulling wheel, at least one of said dams including a deflector directed in the direction of its respective mulling wheel to impel at least a portion of said material toward the respective mulling wheel to control the retention time of the material in the receptacle, and a plow following behind each mulling wheel to scrape material from the mulling surface and to disperse the material in the receptacle about the axis and over the mulling surface, said plow extending longitudinally in the receptacle and being disposed adjacent the mulling surface.

9. Apparatus for continuously mulling material comprising, a receptacle disposed on a laterally extending axis, said receptacle extending along said axis to define a path of flow for material through the receptacle in a longitudinal direction from one end of the receptacle to the other end of the receptacle, said receptacle comprising a wall having an inwardly facing mulling surface on which the material is to be mulled, said mulling surface being disposed about said axis, mulling Wheels in said receptacle disposed at successive positions along said axis to successively mull the material as it flows through the receptacle, a dam disposed ahead of each mulling wheel to lead the mulling wheel as it moves about the axis, said dam being directed laterally with respect to said axis in the path of flow of the material to interrupt the flow of material and to confine material in front of a mulling wheel to be mulled by the mulling wheel, said dam being a planar element that is disposed laterally with respect to said axis, a portion of said dam being bent out of the plane of the dam in the axial direction of the receptacle to form a deflectorto impel at least a portion of the material in the axial direction of said receptacle to control the retention time of the material in the receptacle, and a plow following behind each mulling wheel to scrape material from the mulling surface and to disperse the material in the receptacle about the axis and over the mulling surface, said plow extending longitudinally in the receptacle and being disposed adjacent the mulling surface.

10. Apparatus for continuously mulling material as recited in claim 9, in which said deflector is formed at the leading edge of said dam, another deflector is formed at the trailing edge of said dam by a portion of the dam which is bent out of the plane of the dam in the axial direction of the receptacle to form a deflector to impel at least a portion of the material in the axial direction of said receptacle to control the retention time of the material in the receptacle.

11. Apparatus for continuously mulling material as recited in claim 10, in which said bent portion of said dam for the first said deflector at the leading edge of the dam and said bent portion of said dam for the second said deflector at the trailing edge of the dam are bent in opposite directions in order to impel the material in the same axial direction.

12. Apparatus for continuously mulling material as recited in claim 9, in which said planar element of the dam has an arcuate outer edge that is disposed adjacent the inwardly facing mulling surface of said receptacle, and said 'bent portion of said dam comprises a vane at the outer edge of said planar element to form said deflector.

13. Apparatus for continuously mulling material as recited in claim 12, in which said vane is disposed at the leading edge of said dam.

14. Apparatus for continuously mulling material as recited in claim 12, in which said vane is disposed at the trailing edge of said dam.

15. Apparatus for continuously mulling material as recited in claim 12, in which said vane is disposed at the leading edge of said dam and comprising another vane disposed at the trailing edge of said dam, and said vanes being disposed in the same direction to impel the material in the same axial direction of said receptacle.

References Cited UNITED STATES PATENTS 378,879 3/1888 Frisbee 241124 X 469,145 2/1892 Hughes 241-130 X 1,736,394 11/1929 Dierker 241-161 2,575,410 11/1951 Davis 241-166 X 3,263,967 8/1966 Simmons 241-ll0 X 3,321,187 5/1967 Simmons 241-256 X ROBERT C. RIORDON, Primary Examiner D. G. KELLY, Assistant Examiner US. Cl. X.R. 241 -466, 124

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