US1393092A - Method of and means for reclaiming molding-sand - Google Patents

Description

J. C. DAVIS.

METHOD OF AND MEANS FOR RECLAIMI NG MOLDING SAND.

APPLICATION FILED MAY 2, I918.

2 SHEETS-SHEET 1.

3. C. BAX/8.

METHOD OF AND MEANS FOR RECLAIMING MOLDING SAND.'

APPLICATION FILE-D MAY 2. H18.

I Patented. Oct

2 SHEETS-SHEET 2.

JZZUQILZLOJ" (70656? flaaos W M JAMES C.

DAVIS, OF HINSDALE, IiLINOIS, ASSIGNOR TO AMERICAN STEEL FOUND- RIES, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW JERSEY.

METHOD OF AND MEANS FOR RECLA IMING- MOLDING-SAND.

Application. filed May 2, 1918.

To all whom it may concern:

Be it known that I, JAMEs'C. Davis, a citizen of the United States, residing at Hinsdale, in the county of Cook and State of lllinois, have inrented certain new and useful Improvements in Methods of and Means for Reclaiming Molding-Sand, of which the following is a specification.

This invention relates to a method of and means for reclaiming molding sand.

One of the objects of this invention is to reclaim used molding sand in a novel and efficient manner.

Another object is to provide a simple, compact and durable device by means of which molding sand may be thoroughly cleaned for permitting-its further use.

These and other objects are accomplished by means of the mechanism disclosed by the accompanying sheets of drawings, in which- Figure 1 is a front elevation, parts being in section, of my sand reclaimer;

Fig. 2 is a fragmentary detail sectional view of the sand reclaimer, showing the fan or beater for violently treating the sand and also showing the sand and dust exits;

Fig. 3 is a front elevation of a sand separator attachment; and,

Fig. 4 is a detail sectional view, taken in the planes of irregular line Of 4.-& of Fig. 1.

Molding sand and bonding material are relatively expensive and where molding is done on a large scale the handling of such material is one which must be seriously considered, even though the sand is disposed of after once being used. erely using sand a single time is extremely uneconomical. Therefore, the question of reclaiming sand after it has been used is one which has been considered seriously, especially by com panies doing foundry work on a large scale.

It is a well appreciated fact in the molding art that the voids of sand, or, in other words, the spaces between the grains of sand serve an important function of permitting the escape of gases during the pouring of a mold. Accordingly, the greater amount of voids, the more readily will the gases escape. However, it is necessary that the grains of sand-be bound together to a certain degree by some medium, such as ground clay, and the like.

Care must be taken to avoid the use of an excess amount of bond material, not only Specification of Letters Patent.

,in condition for further use.

Patented Dot. 111, i921.

Serial No. 232,114

number of defective causes in the foundry product. All bonding materials have a relatively low fusing point, and, as stated above, also to more effectively serve their purpose, the bonding materials are ground and ulverized to a very fine consistency and t ese qualities constitute their inherent weakness and distract from their permanency by reducing thei-rability to withstand the high temperatures which are developed in the casting period and to whichthe sand in immediate contact and adjacent the casting is subjected. Molding sand is a poor conductor of heat, due primarily to the voids and the presence of air therein, and as a consequence the high temperature resulting from the molten metal does not extend beyond a point relatively close to the mold cavity. The bonding material-beyond this zone of high temperature does not become heated to a point which. has a very material effect on its condition, and for that reason the simple process of cutting up or mixing or tempering is sufficient renovation to a ain place it 6n the other hand, the bonding material which is contained in the high temperature area' suffers a decided change and by total disintegration or surface fusion, loses permanently its bonding or adhesive properties. The grains of sand composing the layer of sand which comes in contact with the molten metal are fused immediately into a thin scale and rendered useless for any further purpose. The remaining sand grains within the high temperature zone, and which do not come in contact with the metal, are heated to a point of iLiH-HClGSCBIlCB and perhaps to surface fusion. The bonding material with which it is surrounded and which is less susceptible to high temperature, is totally reduced and in this condition combines with the fused or partially fused surface of the sand grains. Owing to the plastic condition of these sand grains, the decomposed bonding material is embedded or attached firmly to the surface of the sand. This transformation is an important one from a standpoint of reclaiming, and it is admittedly the one problem which is difiicult to overcome. The tenacity with which this decomposed bond is attached or fused to the surface of the sand is remarkable. To prepare grains of sand in this condition for reuse is the result of continued experiment for a long period of time. I find that to prepare grains of sand inthis condition for reuse requires a process of some mechanical violence and the severity of the action must be suflicient to break down and remove from a large portion of the sand grains the attached particles; of decomposed bonding material. 7

By means of my method and the mechanism shown, the used sand is fed to a rapidly revolving bladed member, which strikes the grains of sand with tremendous force, driving the grains againstthe walls of a receptacle for breaking away the decomposed bonding material and the fused surface formed on the grains of sand, the sand being cleaned by abrasion and attrition, both by the sand grains being violently treated and agitated one against the other and by driving the individual sandgrains against the cleaning surface of the receptacle in By referring to the figures of the draw- -ings it will be noted that 1 have shown a scrubbing chamber 10, with a tangential outlet 11 for the exit of the sand after it has been cleaned. Fitting within this chamber.

10 at the bottom, where the greatest abrasion is localized is a wearingring 12. This ring is so arranged that it can be withdrawn and replaced when it becomes worn, thus protecting the remainder of theapparatus from excessive wear. Rotatively mounted in the scrubbing chamber 10 is a disk 13, preferably of steel, provided with a relatively large number of radially and verti-- cally extending blades or wings 1 1. This fan structure is mountel upon a vertically arranged shaft 15, whi ch is driven by a motor 16 directly connected to the shaft.

, Directly above the main scrubbing chamber 10 is an annular drum 17, which serves as a dust separating device. This drum also is provlded with a tangential openmg or exit disposal. In practice dust collectors are connected directly to the outlet-of the drum. This drum 17 has a bottom circular flange 19, which extends radiallytoward the center 1 thereof and serves as a partition or baffleto prevent the sand grains from entering the drum or dust chamber 17, thereby serving the purpose of a separator. The top of the drum 17 is closed, with the exception of an opening 20 in the center from which conduit 21 extends down into close proximity to the fan 13. Air passes down through the pipe or conduit 21, said conduit preventing this .clean air which passes therethrough from interfering with the upward flow of dust-laden air passing from chamber 10 into the chamber or drum 17. This conduit 21 also serves the function of guiding the air currents' 1n the proper.d1rect1on, which is facilitated by means of the circular flange 22, formed at the bottom of the conduit 20.; In order to facilitate the supply of air to the conduit 21, the motor 16 is elevated and supported by a spider 23.

Extending down through the conduit 21 is a suitable feed pipe 24:, which directs the flow of sand from. a source of supply 25 to the. revolvingfan 13 near the center thereof Directly below the fan 13 is a bowl shaped bottom plate 26, which-provides clearance below the fan for taking care of any surplus sand in the event that the machine is fed too heavily. It will be noted that this plate 26 is provided with holes 27 fort-he automatic discharge of any surplus sanda'nd also for any scale or foreign matter which may he accidentally fed into the machine.

. In the operation of this machine, the motor 16 is set in motion thereby causing the fan to be rotated at a relatively high rate of speed. The blades or wings 14 act as a horizontal fan, creating a circular movement of the air within the chamber 10. Centrifu' gal force causes this air to crowd away from the center of the chamber thereby forming a vacuum, which creates a suction of clean;

air down through the conduit 21. The air which enters through the conduit 21 is circulated through the chambers 10 and 17 and is discharged through the dust outlet. 18.

Sand is fed intozthe supply pipe 2 1 in a continuous streamequal'to the capacity of the machine and is directed onto the central portion of the rapidly revolving fan 13. Through centrifugal force and aided by the blades 14:, the used sand is swept with terrific velocity out against the wearing ring 12 in the scrubbing zone. r Due to its tangential trajectory imparted by the movement of the rotating fan and consequently aided by the circular movement of the air blast created also by the fan blades, the sand travels in a helical direction upward until it strikes the sand outlet '11, when it is ejected from the 65 p 18 for carrying ofi' dust laden air to apropermachine through the medium of its own 1 0 momentum. The flange 19, at the bottom of chamber 17 prevents any of the sand from entering the auxiliary chamber 17 and compels its continued circular travel until it takes the natural outlet 11 in the regular manner hereinabove described Owing to the air pressure created within the device and also the pressure of the air entering through the conduit 21, the dust laden air passing from chamber 10 to chamber 17 is forced out of the scrubber and through the opening 18 toward a dust collector.

If it is desired to separate the large grains of sand from the smaller grains, the same may be accomplished by means of a separating device 28, which may be connected to the exit conduit 29 of the scrubber. This separating device may be of any suitable type. The one herein disclosed includes a chute 30, through which the sand passes and is directed down over plates 31 which are pivotally mounted at a central point 32 by means of which their inclination may be varied. Air may be drawn through the spaces 33 between the plates 31 and exhaust, ed through the rear of the plates and out through the upper exit 3 1 of the separator. In this way the lighter or smaller grains of sand will be drawn into the passageways 33, by the suction of the air and will fall upon the plates. Thus grains which are drawn over the plates 31 will fall into the rear chamber 35 and may be removed therefrom by opening a door 36. Some of the heavier grains of sand which fall directly past the front edges of the plates 31 are drawn into the passageways 33 and slide downwardly thereon, passing from the separator through a chute 37. In this manner reclaimed sand may be separated into different grades. This separator also acts as an additional means for freeing the sand of any dust which may have passed through the discharge opening 11 of the scrubber.

It will be appreciated, of course, that Various types of separators and auxiliary cleaners may be used in connection with my scrubber, also my sand reclaiming device may take various forms and it is my intention to cover all such modifications of forms, falling within the spirit and scope of the following claims.

I claim:

1. An apparatus for reclaiming used mold ing sand, including in combination, a casing, a horizontally rotatable fan therein, means for delivering the used sand to said fan near the center thereof, a horizontally disposed flange extending inwardly of said casing above said fan, said flange defining an opening of less size than the casing, the

casing having an exit opening immediately beneath said flange and also an exit opening above saidflange, meansfor driving said fan, the latter driving the sand against the walls of the casing, and giving the sand an upward helical motion whereby the sand is driven against said flange and outwardly over said lower exit. I

2. An apparatus for reclaiming used molding sand, including in combination, a casing, a horizontally rotatable fan therein, means for delivering the used sand to said tan near the center thereof, a horizontally disposed flange extending inwardly of said casing above said fan, said flange defining an opening of less size than the casing, the casing having an exit opening immediately beneath said flange and also an exit opening above said ring, means for driving said fan,

the latter driving thesand against the walls of the casing, and giving the sand an upward motion whereby the sand is driven against said flange and outwardly over said lower exit.

3. In a device for reclaiming used molding sand, including in combination, a plurality of communicating chambers, each chamber having an outlet, a fan in one of said chambers, a partition between said chambers to restrict the passage-way therebetween, means for supplying used sand to said fan," means for rotating said fan whereby said fan causes said sand to be driven against the walls of said chamber adjacent said fan for cleaning it and be passed out through the outlet in said chamber and causing dust removed from said sand to pass into the other cham-' her and outwardly through its opening, said partition serving to prevent the sand from passing from one chamber to the other.

4. The method of reclaiming used molding sand, consisting in imparting a velocity to the sand, and delivering said moving stream of sand against a relatively fixed surface for cleaning said sand and then removing by a stream of air the refuse broken from the sand by the impact with the fixed surface and with adjacent sand grains.

5. The method of reclaiming used molding sand, consisting first in subjecting said sand -to a violent centrifugal motion and then selectively discharging the cleaned sand and the-refuse material removed therefrom, said discharging being effected by reason of air currents set up by said centrifugal motion.

Signed at Chicago, Illinois, this 16th day of April, 1918.

JAMES C. DAVIS

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