US2264610A - Method of conditioning or treating molding sand - Google Patents

Description

v 1941- E. o. BEARDSLEY 2,264,610

METHOD OF CONDITIONING OR TREATING MOLDING SAND Original Filed S eP tLlZ, 1940 2 Sheets-Sheet 1 Dec. 2, 1941. E. o. BEARDSLEY 2,264,610

- METHOD OF" conmmonme 0R TREATING MOLDING SAND Original Filed Sept. 12, 1940 2 Sheets-Sheet 2 5221612707 flmerfibeardilsy Patented Dec. 2, 1941 UNITED STATES PATENT. OFFICE METHOD OF CONDITIONING OR. TREATING MOLDIN G SAND Elmer 0. Beardsley, Chicago, Ill., assignor to The Beardsley & Piper Company, Chicago, Ill.

Original application September 12, 1940, Serial Divided. and application May 7, 1941, Serial N0. 392,250

Claims. (Cl. 22-217) terns and hence produces rough and undesirable molds or molds which require patching.

The main or primary object of this invention is the provision of a method of treating or conditioning molding sand which contemplates in connection with a sand mulling operation reducing the temperature of the sand to substantially room temperature. By reducing the temperature placing it, together with suitable bonding mate- I rial, in a receptacle and subjecting it while in the receptacle to the action of rotary mulling elements and plow-like deflectors. The mulling operation serves to break up any lumps in the sand and, in addition, to aerate the sand and mix the bonding material with it. During the mulling operation water is added to the sand in order to moisten it and increase its bonding strength. The amount of water which is added to the sand is critical and hence of extreme imof the sand to substantially room temperature during mulling of the sand it is possible readily and efficiently to control the moisture content of the sand and also to eliminate sticking of the sand to the patterns. With eflicient moisture control and the elimination of sticking smooth and useable molds are obtained when the sand is rammed into the flasks.

Another object of the invention is to provide a method of treating or conditioning molding sand which comprehends mulling the sand while it is portance If t much wat rjsaddgd t t sand in suspension and a moistened condition and during the mulling operation the permeability of the sand is so reduced that the gases emanating from the molten metal during pouring can not escape through the sand'and result in blowing of the sand and defective castings. If too small an amount of water is added to, or introduced into, the sand in connection with mulling thereof the sand, when rammed or packed into the flasks, is so dry that it crumbles when contacted by the molten metal and imperfect or unuseable castings result. In most foundries the molding sand is repeatedly used for molding purposes from morning to night. Because of the rev peated or successive high temperature to which the sand is subjected during the day there is a gradual increase of the temperature of the sand and toward the end of the daythe sand sometimes is at an extremely high temperature. When the sand reaches a high temperature, such for example, as 125 F. to 175 F., the water or moisture in the sand evaporates quickly and hence it is practically impossible for the operator of the mulling apparatus so to control or regulate the introduction of water into the sand during mulling thereof that the sand has the correct or proper moisture content when rammed into the flasks. Another disadvantage or objection to the use of hot sand, that is, sand at a temperature of F. or more above room or atmospheric temperature, is that when the sand is rammed or packed into the flasks the lower or room temperature patterns in the flasks draw toward them. an appreciable amount of moisture from the sand cooling the sand by passing or flowing air under pressur through the sand while it is in suspension.

Other'objects of the invention and the variousadvantages and characteristics of the present sand treating or conditioning method will be apparent from a consideration of the following detailed description.

The invention consists in the method which is hereinafter set forth and is more particularly delined by claims at the conclusion hereof.

In the drawings which accompany and form a part of this specification or disclosure and in which like numerals of reference denote corresponding parts throughout the several views:

Figure 1 is a vertical section of an apparatus for carrying out the improved method; and

Figures 2 and 3 are horizontal sections taken respectively on the lines 22 and 3-3 of Figure 1.

Th improved method is designed or adapted to be carried out in the apparatus which is shown in the drawings. In general it comprehends as steps first removing molding sand from flasks after pouring of the latter, then while the sand is in a heated condition due to contact with the molten metal, mulling the sand and simultaneously reducing the temperature thereof to substantially that of the surrounding atmosphere by circulating air under pressure'through the sand and finally, after mulling and cooling, reusing the sand for mold forming purposes. The improved method also, comprehends removal of dust or fines from the'sand at the beginning of with the result that the sand sticks to the patthe mulling and cooling operation and in addition the introduction of water into the sand in order to give the latter the desired moisture content and also facilitate temperature reduction or cooling of the sand.

The apparatus which is shown in the drawings is expressly designed or adapted to carry out the aforesaid method. It comprises a bowl-like receptacle 4, a rotary crosshead 5, a pair of rotary mulling elements 6, a pair of scrapers 1, and a pair of plow-lik deflectors 8. In addition the apparatus comprises a blower 9 for circulating air under pressure through the receptacle in connection with mulling of the sand, a dust arrester ID for removing dust particles and fines from the sand, and a suction fan II for drawing the dustladen air into the dust arrester for dust removal purposes. The apparatus is essentially of the batch-type and is designed or adapted to mull and condition successive batches of sand.

' The receptacle 4 of the apparatus is adapted in connection with a mulling operation to receive a batch or charge of molding sand for mulling and conditioning purposes immediately after the sand has been removed from flasks and while it is in a heated condition. It consists of a flat circular bottom l2 and an annular upstanding side wall I3. A plurality of upstanding laterally spaced leg l4 serve to support the receptacle in an elevated position with respect to the floor of the foundry Or other establishment in which the apparatus is employed. The side wall l3 of the receptacle is cylindrical and forms or constitutes a trackior the rotary mulling elements 6. In addition to the bottom l2 and the side wall it, the receptacle comprises a cylin-- an endless belt conveyor H. The latter, as shown in Figure 1 of the drawings, extends horizontally and has the discharge end thereof disposed in an opening it in the upper margin of the shell I5. When a batch of sand to be treated is placed on the upper reach of the conveyor and the i conveyor is driven in the proper direction the sand is fed into the top of the shell l5 and then drops downwards into the receptacle 4. A doorway ll permits the sand after treatment to be discharged from the receptacle. This doorway is normally closed by a door 20. A fluid pressure operated mechanism 2| (shown in a fragmentary manner in Figure 3) serves to shift the door back and forth between its closed and open positions. When the apparatus is to be used a batch of molding sand i introduced into the receptacle by way of the endless conveyor l1 and then, after being mulled or otherwise treated, as hereinafter described, is discharged via the doorway l9.

The crosshead 5 is located in the central portion of the receptacle directly over the bottom l2 for rotating the cross head driving shaft and effecting drive or rotation of said mulling elements, scrapers and deflectors. The motor 22, as shown in Figure 1, is mounted on a bracket 23 on one of the legs ll. The crosshead 5 embodies at its ends a pair of shafts 24. These shafts extend vertically and fit within and project above and below a pair of tubular sockets 25 at the ends of the crosshead. A horizontal rotary screen 26 is associated with and connected for drive by the crosshead 5. This screen is disposed in the upper end of the shell l5 directly beneath the discharge end of the endless conveyor H and operates to scatter and evenly distribute the batch of sand to be treated innuediately before it enters the receptacle 4. A vertically extending shaft 21 and a bracket 28 conand carries and supports the mulling elements.

scrapers and deflectors. It is adapted to rotate on a vertically extending axis and embodies a depending drive shaft (see Fig. 3). The latter extends through a central hole in the receptacle bottom and is suitably journaled in a housing 2|. An electric motor 22 and suitable speed reducing gearing in the housing 2| serve as the medium nect the screen for drive by the crosshead.

The mulling elements 6 are disposed in the upper portion of the receptacle 4 and are in the form of wheels. They consist of cast metal bodies and solid rubber tires and are carried by a pair of horizontally extending arms 29 so that they are permitted to swing outwards towards the receptacle side wall. The arms 29 are disposed above the crosshead 5 and have'sleeve-like members 30 which are rotatably mounted on the upper ends of the shafts 24. Said shafts and the sleeve-like members 30 serve as connections between the arms and the crosshead whereby the arms, together with the wheel-type mulling elements 5 are caused to travel around the receptacle during operation thereof and at the same time are permitted to swing outwards in response to centrifugal force during drive of the crosshead. The elements 6 extend horizontally and are adapted, in connection with drive of the crosshead, to travel around the receptacle side wall and in addition to spin and efiect mulling of the sand by squeezing it against the side wall. They are rotatably mounted on vertically extending shafts at the distal ends of the arms 29. Chains 3| serve to limit or restrict outward movement. During drive of the crosshead by the motor 22 the mulling elements swing outwards toward the receptacle side wall and, as hereinbefore pointed out, are caused in response to the action of the arms 29 to travel in a circular course around the side wall. As the elements engage the sand around the inner periphery of the receptacle side wall, they squeeze it and in this manner mull it and effect an even or uniform distribution of any bonding material therem.

The scrapers l are adapted to scrape the mulled sand from the receptacle side wall and direct it inwards. They are disposed in the upper portion of the receptacle 4, as shown in Figure l, and are located directly behind the wheel-type mulling elements 6. The upper ends of the shafts 213 have the scrapers fixedly secured thereto and serve as a medium for causing the scrapers to rotate around the receptacle side wall in connection with drive of the crosshead.

The plow-type deflectors 8 are fixed to, and extend outwardly from, the lower ends of the shafts 24 and are positioned behind the scrapers 7. During operation of the apparatus the deflectors 8 serve to deflect the sand upwards and outwards against the upper portion of the inner periphery of the receptacle side wall and into the path of the mulling elements. The deflectors are canted, as illustrated in the drawings, and coact with the scrapers to maintain the sand in 5 suspension in the receptacle during drive of the crosshead. When the apparatus is inoperation with a batch of sand in the receptacle, the sand is first squeezed against the side wall by the mulling elements, then is scraped inwards in the direction of the deflectors and then is thrown outwards and upwards against the side wall and f into the path of the elements and this occurs at such speed the deflectors and scrapers operate to maintain the sand .in suspension in the receptacle.

The blower 9 serves as a means for circulating air through the sand in the receptacle for cooling purposes. It coacts with the dust arrester and the suction fan H to eliminate dust from the sand during a mulling operation and consists of a blade-equipped rotor 32 and a casing 33. The casing 33 is mounted on a frame 34 on the foundry floor and embodies an inlet 35 and a tubular discharge duct 36. A plate valve 35 is associated with the inlet 35 and permits the operator of the apparatus to regulate to any desired degree, or completely out off, the flow of air through the receptacle. When the valve is closed substantially no air under pressure enters the receptacle even though the rotor of the blower is revolving. The outlet end of the discharge duct is disposed beneath the receptacle 4 of the apparatus and is connected to a ring-shaped manifold 31 on the bottom of the inner part of the receptacle bottom |2. Such manifold communicates with the interior of the receptacle by way of an annular series of holes 38 and these holes, as shown in Figures 1 and 3, extend through the receptacle bottom wall and are located inwardly of .the deflectors 8. The blade equipped rotor 32 is disposed in the casing 33 and is adapted to be driven at a constant speed by an electric motor (not shown). When the blower motor is in operation and the inlet 35 of the blower casing is either partially or fully open the rotor 32 operates to draw outside air into the casing via the inlet. Such air is placed under pressure and is forced through the outlet duct 36 into the manifold 31. From the manifold the air under pressure flows upwards through the holes 38 into the interior of the receptacle. A ring-shaped battle-plate 39 is carried by the lower ends of the shafts 21 and operates to deflect the air under pressure so that after entering the receptacle it flows outwards across the outer part of the receptacle bottom and then upwards through the sand in suspension. As the air under pressure passes upwards through the sand it serves not only to cool the grains of sand but also to aerate the sand. From the receptacle the air under pressure passes upwards into the upper portion of the cylindrical shell 20. A ringshaped rib 40 is connected to and projects upcated, the sand is generally at a comparatively high temperature before it enters the receptacle and this is due to contact with the molten metal. By cooling the sand as it is mulled it is possible accurately to control or regulate the moisture content of the sand and also to prevent the sand from sticking or adhering to the patterns.

The dust arrester I0 is located adjacent the 4 upper portion of the cylindrical shell Hi. It embodies a housing 4| and suitable or conventional dust arresting elements (not shown) in the housing 4|.

42 and an air outlet duct 43. The inlet duct 42 extends between the upper portion of the housing 4| and the upper margin of the cylindrical shell |5. It effects communication betweenthe shell interior and the housing interior and has a valve 44 for controlling the flow of air into the dust arrester Ill. The outlet duct 44 is located at the bottom or lower end of the housing 4|, as shown in Figure 1. The suction Ian M is associated with the outlet duct 43 and when in operation or effective serves to draw air from the interior of the shell l8 through the duct 42 and into the housing 4|. It is of the centrifugal type and includes a casing 45 and a blade-equipped rotor 46. The casing has an air inlet in communication with the outlet. duct 45 and embodies a discharge duct 41. The fan is adapted to be constantly driven during use of the apparatus. In the event that the valve 44 is closed no air from p the receptacle flows into the dust arrester houswardly from the inner part of the receptacleing although however a vacuum is built up within the housing. Such vacuum results in an immediate inflow of air into the housing when the valve 44 is opened. When air with dust or fines is drawn into the housing 4| of the dust arrester I 0 the dust arresting elements in the housing serve to filter out and remove the particles and fines prior to egress of the air from the housing. When a batch of sand is delivered into the receptacle and the valves 35 and 44 are either fully or partially opened the dust particles and fines in the sand are directed upwards by the air under pressure flowing upwards through the receptacle and are drawn into the housing 4| where, as previously described, they are removed from the air.

In addition to the previously described parts or elements, the apparatus comprises a pipe 48 for introducing water into the sand in the receptacle. This pipe is disposed exteriorly of the receptacle 4 and is adapted to receivewater'under pressure from any suitable source of supply. It is preferably located adjacent the blower 9 and terminates as far as the discharge end thereof is concerned, in two branch pipes 49 and 50. The branch pipe 49 extends upwardly along the,

is adapted when water under pressure is permitted to flow into it through the branch pipe 49, to jet streams of water downwardly and inwardly onto the sand in the receptacle. A valve 53 is included in the branch pipe 49 so as to regulate the flow of water therethrough. The branch pipe 50 is arranged so that the discharge end thereof extends through the outer part of the receptacle bottom I2. It is adapted to supply a portion of water from the main water pipe 48 directly into the receptacle and includes a valve 54 for regulating the flow of water under The housing embodies an" air inlet duct pressure therethrough. The main pipe 48 includes a flow meter 55 so that the operator of the apparatus may ascertain the amount of water introduced into the sand. A main control valve 55 is connected to the water pipe 48 between the flow meter 55 and the branch pipes 49 and 50. When this valve is closed no water flows into the two branch pipes. Usually the valves 53 and 54 are set so that a part of the water which is introduced into the sand for moistening purposes fiows through the spray pipe and the remainder into the bottom of the receptacle via the branch 50. With the valves 53 and 54 set in this manner opening of the main valve 56 results in introduction of water into the sand. The water which is introduced into the receptacle via the branch pipe 50 flows over the bottom wall of the receptacle and is mixed with the grains of sand due to the action of the plow-like deflectors 8. When the sand in the receptacle is moistened and air under pressure is circulated through it quick cooling of the sand takes place due to evaporation of a part of the moisture.

The apparatus may be operated in either of two diiferent ways or manners. Firstly, it may be operated so as to effect mulling and cooling of the sand and also removal of the dust and fines in the sand. Secondly, it may be operated in such manner that the desired mulling and cooling of the sand are effected without any re: moval of the fines. When the first mentioned manner or way of operation is desired the motor 22, the blower 9 and the suction fan H are first started. As soon as current is supplied to the motor 22 the -mulling elements, scrapers and plow-like deflectors are caused to swing or travel in a circular course around the inner face of the side wall [3 of the receptacle. Before the sand to be mulled is introduced into the receptacle the valves 35 and 44 are partially closed. After this operation the sand to be mulled .is introduced into the upper end of the shell l by way of the endless conveyor ll. It is contemplated that the sand to be mulled be removed from the flasks immediately after use thereof and while it is in a heated condition due to contact with the molten metal. As soon as the sand enters the shell it is scattered by way of the rotary screen 25. As the sand descends or drops into the receptacle in a scattered condition the air under pressure from the blower 9 elevates the dust and fines and brings them within the vicinity of the duct 43. As soon as the dust and fines reach such vicinity they are drawn into the housing 4| of the dust arrester ID in response to the action of the suction fan ll. As previously pointed out, the dust and fines are removed from the air during passage of the air through the housing 4|. After introduction of the sand into the receptacle the valve 56 in the main pipe line 48 is opened until the desired amount of water is discharged into the receptacle via the branch pipe 50 and the spray pipe 5|. As soon as the desired amount of water has been introduced into the sand the valve 55 is closed. The sand, after entry into the receptacle, is subjected to the action of the mulling elements 6, the scrapers i and the plow type deflectors 8. Immediately after moistening of the sand the valves 35 and 44 are fully opened. As soon as these valves are opened to their fullest extent rapid cooling of the sand takes place because of the up-flow of air under pressure through the sand while the latter is in suspension in the receptacle. Cooling of the sand results from the up-flow of air in the receptacle and evaporation of a part of the water or moisture in the sand. At the start of the mulling operation the valves 35 and 44 cannot be fully opened because some of the molding sand would be drawn into the dust arrester and lost. It is contemplated that the operator of the apparatus will set the valves so that during entry of the sand into the receptacle only the dust and fines of a particular size will be eliminated. When the valves 35 and 44 are fully opened after the sand has been moistened no sand is lost because the sand is heavy due to moistening. The elements 6 during drive On the crosshead serve to squeeze the sand against the receptacle side wall and thus mull it and the scrapers and deflectors operate, as hereinbefore described, to maintain the sand in suspension over the receptacle bottom and position it for mulling by the mulling elements. At the conclusion of the mulling operation the door 20 is opened by manipulation of the mechanism 2|. As soon as the door is swung into its open position the plow-like deflectors 8 fling the mulled and cooled sand out of the receptacle via the doorway I9.

When it is desired to operate the apparatus in such manner as to remove no fines in the sand the motor 22, the blower 9 and the suction fan I I are first set into operation. Thereafter the valves 35 and 44 are fully closed. With these valves in their fully closed position no air under pressure circulates upwardly through the receptacle and shell. As soon as the valves are closed the sand to be treated is introduced into the upper end of the shell by way of the endless conveyor ll. As the sand is being scattered by the screen the valve 56 is opened and this results in moistening oi the sand. When the proper or desired amount of water has been introduced and the sand is hence in such a condition that air under pressure will not disturb the fines in the sand the valves 35 and 44 are opened. Upon opening of these valves the blower operates to flow upwards through the sand in the receptacle a constant stream of air under pressure and such air cools the sand. The suction fan ll assists the blower in effecting a rapid circulation of air through the receptacle and shell. It is contemplated that the blower and suction fan be of such capacity that the air which is circulated by them in connection with operation of the apparatus will reduce the sand to room temperature during the course of its mulling period. The suction fan ll prevents a positive pressure within the receptacle and shell and this is of importance since such a pressure might result in sand being forced or blown through the sand inlet opening l8. By having the valve 44 in the inlet duct 43 as distinguished from the discharge duct 47 suction is built up in the housing 41 of the dust arrester prior to opening of the said valve in connection with a mulling operation. With suction in the housing there is immediate up-flow of air through the sand and cooling of the latter immediately takes place when the valves 35 and 44 are opened by the operator.

The method which is carried out when the aforementioned apparatus is used in either of the two manners mentioned or described is essentially a simple one and results in improved or better casting from the treated sand.

The invention is not to be understood as restricted to the details set forth, since these may be modified within the scope of the appended claims without departing from the spirit and scope of the invention.

This application is a division of an application for United States Letters Patent filed by me on September 12, 1940, and serially numbered Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. That improvement in foundry practice which comprises first delivering into a chamber heated molding sand recovered from flasks, and then while the sand is in'the chamber conditioning and cooling it for re-use by repeatedly and alternately pressure squeezing and scattering the.

sand and simultaneously circulating air under pressure through the chamber past the scattered sand.

2. That improvement in foundry practice which comprises first confining a batch of hot previously used molding sand in a chamber, moistening the sand, and then for a predetermined period subjecting the confined batch of moistened sand to repeated and alternate pressure squeezing and scattering actions while at the same time circulating air under pressure through the chamber and past the scattered sand for sand cooling purposes.

3. That improvement in foundry practice which comprises moistening a batch of hot previously used molding'sand; introducing the batch into a substantially vertical bowl-shaped receptacle; and then for a predetermined period repeatedly and alternately squeezing the moistened sand against the side wall of the receptacle and scattering the sand in the receptacle while maintaining it in suspension, and simultaneously circulating air under pressure upwardly through the receptacle and past the scattered and suspended said for sand cooling purposes.

' 4. That improvement in'foundry practice which comprises introducing molding sand into a substantially closed chamber, and then subjecting the sand in the chamber to repeated and alternate squeezing and scattering actions and at the same time introducing air under pressure into the chamber so that it circulates through the scattered sand, and drawing of! the circulated air from the chamber and cleaning it.

5. That improvement in foundry practice which comprises introducing hot previously used molding sand into a chamber and for a predetermined period subjecting the sand in the chamber to repeated and alternate squeezing and scattering actions, and during said period first circulating

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