US2263797A

US2263797A - Timer for sand mixers

Info

Publication number: US2263797A
Application number: US344756A
Authority: US
Inventors: Alfred C Christensen
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-07-10
Filing date: 1940-07-10
Publication date: 1941-11-25
Anticipated expiration: 1958-11-25
Also published as: US2277953A

Description

2 Sheets-Shet l W? E Em $1M.

$5.13 evil h F m n E V. n

v. 25, 1.941. A. c. CHRISTENSEN TIMER FOR SAND MIXERS Filed July 10, 1940 H e 5 n 6 1L r h PL a a e r U A Nov. 25, 1941. A. c. CHRISTENSEN TIMER FOR SAND MIXERS Filed July 10, 1940 ,2 Sheets-Sheet 2 M 9 .3 c ,1 L K v m. a y fw rm 0 mm m G 2 mm 7N0 6 TOW Q at; 3.5 uwhu una my IIII'IIIII I nz Eri If JUffea C C/HJ'SZLGTISGH Patented Nov. 25, 1941 TIMER FOR SAND MIXERS' Alfred C. Christensen, Chicago, 111., assignor to Herbert S. Simpson, Ch.icago, 111.

Application July 10, 1940, semi not 344,756

4v Claims.

It has been the practice infoundries to-recondition and reuse the sand from foundry molds after the removal of castings. The process usually consists in breakingup the previously used sand molds andremoving metal particles and the liketherefrom before the used sand is deposited in a mulling and mixing machine. The used sand is usually first broken up and then mulled and mixed, after which selected dry ingredients are delivered into the mixing-crib, to which mixture water in proper quantity is added and mixed before the reconditioned sand is discharged from the-mixer for reuse.

The various steps in the treatment of foundry sands have heretofore usually been manually controlled and it has been necessary to=rely upon an operators ability and discretion as to the duration of the mixing periods, the percentage of moisture content of the sand to be treated, and the quantity of water to be added for different batches and. kinds of sand.

The present invention relates to an improved type of an automatic timer or control for definitely timing, by electrical control, the duration of the various opera tions in a foundry sand mulling cycle, the recording of the moisture content of the sand, the quantity of-wat'er required to be added to the dry mixture, and the timing of the discharge of the conditioned product.

It is an object of this invention to provide an automatic time control for governing the steps in the reconditioningro'f used mold sand in continuous types of foundry sand conditioning systerms.

It is also an object oi. this invention to provide a foundry sand reconditioning installation having an autom-atictiming unit connected in the system and adapted to: be setfor definitely determining the timing of the. various steps in the cycle.- of operations of the reconditioning of foundry sand.

Another object of the invention is the provision of a time, master for; a foundry sand reconditioning installation, with said time master including, a plurality or controls connected with different parts of the installation for governing the timing" of the mixing period, as well as the timing of the introduction of" the various materials and thefinalidischarge of the reconditioned product from theinstallation.

A further object of the invention is the provision of a time master" for use; in connection with a foundry and reconditioning installation, said time master" including a series of automatic timers for governing the various steps in the cycle of operations and also including a moisture tester for the: used" sand to definitely determine the quantityof water to be added to thesand for proper reconditioning of the same.

It isa further object of this invention to provide a foundry sand mixing-machine with a time control unit including amaster automatic time switch and av plurality of auxiliary time switches for governing the operation of the batch delivery door, the timing of the'dry mixing, the determining ofthe quantity or water to be added to the mixture, thetimlng of the discharge of the reconditioned sand, and'finally; the resetting of the: timers for repeating the cycle of operations.

It is furthermore an object of this invention to provide av time master unit for a foundry sand reconditioning machine, said unit= being constructed to permit ofeither' automatic control of the diflferent steps in the cycle of operati'ons of reconditioning sand or manual control of the various stepsv of the cyclefrom thetime master unit.

It is furthermore anajobiect of this invention to provide a sand reconditioning machine with an electrically controlled instrument unit ineluding a series of connected timers for governing the operation of the complete cycle of operations of the machine, the operation of the charge admitting doors, the sampling and testing of the water content or the charge, thetiming of the dry mix period, the timing of the entrance of apredetermined' quantity of liquid to the charge, and eventually; the timlng of the operation of the discharge doors for releasing the reconditioned product from the machine.

It is an important object of this invention to provide a foundry sand mixing machine with a timing unit for the cycle of operation of the machine, said timing unit being arranged for convenient conversion from an automatic type to a. manually controlled type; and furthermore including'a sand sampler connectedwith a moisture: tester to determine the quantity of water to bev added to the mixture and the timing of the delivery of the required. amount of water into the machine.

Still another important object of this inventiorr is the provision of atiming instrument including a series of connected electrical timers adapted to be conveniently set or adjusted for automatically determining the timing of the difierent steps in the cycle of operations for conditioningroundry sands and thelike.

Other and further importantobjects or this Figure 3 is a wiring diagram for the electrical v control of the cycle of operations ofthe machine and including a circuit diagram for the manual control of the cycle of operations.

- As shown on the drawingst, v

- The improved-foundry sand conditioning systern vis illustrated schematically in Figure 1 of .the drawings, with Figure 2 illustrating the steps in the cycle of operations of the sand conditioning system. The reference numeral I indicates a chargev or batch delivering hopper which receives previouslyused foundry mold sand which is t0;berec0ndition ed for reuse. The hopper I,

"at its lower end, is provided with a batch release door 2 which normally closes the discharge opening of the-hopper. Pivotally connected to the .door 2 is the :lower end of a. piston rod or stem 3 which forms a part of an air control mechanism including an air cylinder 4 in which the piston is *slid'ably operated. Air pressure is adapted to beadmitted into the cylinder 4 alternately above and below the head of the piston by means of the pipes or'air tubes 5 and 8 which connect up withasuitable supply of air pressure-controlled" by means of a time switch unit I, of a selected standard type, the internal wiring connections of which are illustrated in the wiring diagram of Figure 3. I 'The time switch unit I is mounted in a control board or-casing 8 positionedon a suitable support at a selected distance from the sand conditioning machine. This time switch control unit I is provided with an outer minute time set .dial 9 operable by a knob II] and an auxiliary or inner second time set dial I I. Both of the time dials 9 and I are adapted to be set. with respect to an index mark |2 positioned on the front face of the casing of the time switch I.

Positioned beneath the sand supply or batch hopper I is a sand mulling and mixing machine consistingof a sand receiving bin or crib I3 supported on a pedestal or) base I4. Mulling and mixing mechanisms, designated, as a whole by the reference-numeral I5, are mounted within the sand crib I3 and are operable by means .of gear sets disposed within gear housings I6 .and IT. The gear mechanisms or sets within the housings I6 and I1 are driven by a driving motor-I8. 'Mounted in the bottom of the crib I 3 are two diametrically opposite'discharge doors adapted to be operated by means of crank arms .I9. Connectedto, the crank arms I9 are the .lower endsjof piston rods 20 which operate in air pressure cylinders 2| mounted on the side of crib' I3. The lower and upper ends of the air -pressure cylinders 2| are respectively connected v.with air pressure supply tubes or pipes 23 and 24. The air tubes, 23, and 24' are connected with ,the source of 1 air pressure through ,adischarge -presser head .93.

door control time switch unit 25 which is mounted in the control board or casing 8 and is provided with minute and second time set dials 9 and I I, adapted to be set for controlling the timing of the operation of the discharge doors of the machine.

Also mounted within th sand crib I3 is a water funnel 26 into which the supply end of a water supply pipe 2'! projects. Connected in the water supply pipe 21 is a control valve 28, on which a water meter 29 is supported. The timing of the delivery of a charge of water into the sand crib is controlled by means of a water control form of time switch unit 33 mounted in the control casing B and being provided with externally adjustable time set minute and second dials 9 and II.

The quantity of water which is to be admitted into the .sand crib I3 for a given batch of sand, is adapted to be accurately determined by means .of an improved sand samplerand moisture content tester, briefiy comprising a channel-shaped sand sampler pocket or cell 3| positioned between the sand crib I3 and the hopper I directly in the path of movement of a charge of sand from the hopper into the crib. Mounted adjacent one end of the sampler cell 3| is an air pressure cylinder 32 provided with a piston mechanism on one end of which an angle-shaped cut-off cover or snubbing head 33 is mounted for coaction with the channel-shaped cell 3| to close the top and one end thereof after a sample of the entering sand has been deposited in said cell. Compressed air is adapted to be admitted into .the cylinder 32 on opposite sides of the piston .nected to a suitable source of air pressure con- .nected with the control casing 8.

Mounted in the control casing 8, and controlling the passage of compressed air through the tubes 34 and 35, is a control valve mechanism. operable by means of a handle or hand grip lever 35.

Mounted adjacent the opposite end of the sand sampler cell 3|, is another air pressure cylinder 31 including a piston mechanism on the outer end of which a sand pressing and discharg head 38 is mounted for cooperation with the sand sampler cell 3| to, first slide into one end of the sand sampler cell 3| to compress the trapped sand therein against the end closing flange of the head 33. Connected with the ends of the air compressor cylinder 3! are the ends of two air pressure supply tubes 22 and 39 adapted to alternately permit air to be admitted alternately against opposite sides of the piston head within the cylinder 31 to cause operation of the The air supply tubes 22 and 39 are connected with a suitable source of air pressure supply by means of an air pressure control valve mounted within the control casing 8 and operable by means of a lever or handle 40.

For the purpose oftesting the moisture content of the sand caught in the cell 3|, moisture testing electrode units 4| are mounted in oppo- The moisture testing units 4| are connected by means of wires or lines :42 and 43 to a standard moisture meter 44 which is providedwith a. suitable dial and an indicating hand to register the moisture content of the trapped sand so that an operator of the machine can determine the amount of additional liquid which is required to be added to the sand in the crib I3. The control dials 9 and II, of the water CQIL JIQI time switch 39, are then set,.so that at a desired time in the cycle of operation'of the machine a predetermined quantity of water or other liquid which is to. be added to the sand batch in the crib I3 may be emitted by the liquid supply pipe 2! into the funnel 26 for delivery into th crib.

In reconditioning a batch of sand delivered from thehopper l' into the crib I3 it often: is desirable to add a quantity of dry substances or ingredients into the batch of sand before liquid isadmitted tothe mixture. For the purpose of controlling the timing of the admittance of the dry materials into the sand a standard drymix time switch unit 45' is mountedin the control casing 8 and is provided with time-set dials 9 and H which are adapted to be set so that the batch of sand and the dry materials addedthereto may be dry-mixed for a predetermined length of time before the admittance of liquid into the mixing crib l3.

Also mounted in the control box or casing 8 is a total cycle control time switch unit 46, which is also provided with a set of minute and second control time-set dials 9 and II adapted to be set to determine the length of the entire cycle of operations of the various steps included in the mulling and mixing of a batch of sand to recondition the same with a proper moisture content.

For the purpose of resetting the various time switches at the end of a cycle of operations the control board or casing 8 is provided with a reset control time switch unit 41 which is connected up with the various other time switches in the control casing 8 for the purposeof resetting the same at a predetermined time in the cycle of operations, to start a new cycle of operations as soon as a previous cycle is completed.

For the purpose of starting and stopping the machine and the various control units connected therewith the control board or casing 8 has mounted therein a main three-way control switch 48 which may be thrown from an open position into a closed position for the automatic operation of the cycle, or into a second closed position to permit manual operation of the cycle.

Figure 2 illustrates diagrammatically the cycle of operations of the machine. The entire cycle of operations is represented by the period of 360 degrees. When it is desired to start the machine the main control switch 48 is closed to cause automatic operation of the machine, starting at the radial line A. The time switch 25, is set to cause operation of the air pressure cylinder devices 2| to start the cycle at the radial line A, to, cause the discharge doors of the bin l3 to open to allow discharge. of the contents of the bin. This operation takes place depending upon the setting of the time dials on the discharge door time switch and the discharge continues until the radial line B is reached, at which time the time switch causes closing of the discharge doors of the bin l'3;

At the same time that the discharge doors close the batch release door 2, controlled by the time switch 1, is opened to permit a predetermined quantity of sand which is to be reconditioned to be discharged into the bin I3. The batch gate 2 will remain open until the desired quantity of sand has been delivered, and, will, then 7 automatically be closed. This operation is indicated by the are C.

During the time that a charge of sand is being delivered from the hopper I into the bin I 3 a sample of the sand is trapped in the moisture tester cell 3| by operating the control levers nected with the water control valve 5|.

3&- andv 40 so that. the moisture meter 4!? will indicate the moisture content. of the sand tobe treated. and will permit the attendant to determine upon the amount of: water or other liquid to; be added to the moisture. This is. done'by the attendant, who sets the water control time switch 30;

The testing of the sand for its moisture content is. doneqduring aperiod between the radial line. B and the radial line D (Figure 2), which is known as the dry-mixing period and v is: controlled by. the time switch During the interval between the. radial lines B and. D the attendant delivers into the bin l3 any additional dry materials which. are. needed for the reconditioning of the particular batch of sand. During the dry-mix period the added materials are thoroughly dry-mixed with the sand.

When the dry mixing period is over the water control time switch 30' acts to cause opening of thewater control valve 28 and operation of the water' meter 29, and keeps the water valve 28 open, depending upon the setting of the. time switch, until the required quantity of water or other liquid is delivered into the funnel 2G for discharge-L into the dry mixture contained within the crib l3. As soon as the required quantity of liquid has been: added the time switch shuts oif. the water valve 28, and this phase of the operation is indicated by the radial line E in Figure 2.

From this point in the cycle of operations the mulling and mixing machine continues to operate from the radial line E for the balance of the cycle. Just prior to the end of the cycle of operations, at the radial line F, the reset time switch 41 is brought into action to automatically reset all. of the time control switches.

The total. cycle time switch 46 has the dials thereof set to determine the length of the total cycle ofoperations. When, the radial line A, in the cycle diagram, is reached after a complete cycle of operations the bin discharge doors are again opened to permit discharge of the reconditioned sand to begin. the next cycle of operations of the machine.

When it is desired to convert the machine from. automatic operation to a manual or handcontrolled machine it is, only necessary to throw the main switch 48 into engagement with the hand control contact of the switch, thereby'cutting off all of the time switches and operating, instead, through manually controlled push button switches such as a door discharge control switch 49, a batch gate control switch 50, and a water supply control switch 5|.

Connected with the discharge door control switch 49 is a solenoid valve 52.. A solenoid valve. 53' is connected with the batch gate control switch 50 and a: solenoid valve 54 is con- The solenoidv control valve units 52-, 5.3 and 54 are also connected with the. respective time switches in the automatic system, as clearly illustrated in the circuit diagram of Figure 3.

Referring now to Figure 3 of the drawings, the control circuit for governing the cycle of operations of the machine comprises power lines 55 and 56 for the supply of an alternating current. The power line55 is connected to an auto matic control contact 51 of the main switch 68; The second or manual control contact 58, of the main switch 48, has connected thereto a circuit line 59 which is respectively connected to the contacts 60-, El and 6 2 of the manually and r are normally open.

operabledischarge control switch 49, 'the batch control switch 50 and the water control switch 5|. The opposite terminal 63 of the discharge control. switch 49 is connected by means of a line 64 to one terminal of the solenoid valve 52. The second terminal 65 of the switch 50 is connected by means of a line 66 to one terminal of the solenoid valve 53, and the second terminal 61 of the switch 5| is' connected by means of a line 68.to one terminal of the solenoid valve 54. The second terminals of the respective solenoid' valves 52, 53 .and 54 are connected by means of a line 69 to the circuit supply line 56.

Included in the circuit are six standard time switches namely, the total cycle time switch 46, thedry' mixing time switch 45, the water addition time switch 30, the discharge door time switch 25, the batch g'ate time switch 1, and the reset time switch. 41. Each of the foregoing standard time switches is provided with eight terminal posts, designated by the letters a, b, c, d, e, f, g, and h. In each of the six time switches the terminal posts 9 and h are connected by a connecting bar jand the terminal posts b and f are connected by a connecting bar 74:. In the time switches 45, 30, 25 and 1, the terminal posts b and c are connected by a connecting bar I. In the reset time switch 41 the connecting bar is omitted between the terminal posts b and c and instead a connecting bar 111. connects the terminal posts and g. In the total cycle time switch 46 the connecting bar between the terminal posts I) and c is omitted, as well as the connecting bar between the terminal posts 1 andg.

Each of the time switches includes a clutch coil 11, a Telechron motor 0 and three switch contacts 11, q and r. In the time switches 45, 46, 30, 25an'd 1, the three switch contacts p, q In thereset time switchv 41 the contacts p and 1 are normally open, while the switch contact q is normally closed.

Connected to the terminal post a of each of the six time switches is a line 10 which is also connected to the power supply line 56. Connected with the terminal post I) of the time switch 46 is one end of a line 1|, the other end of which is connected to the terminal post d of the time switch 41. The terminal post c of 'the time switch 46 is connected by means of a line 12 to the third terminal of the main switch 48. The terminal post cl of the time switch 46 is connected by means of a line 13 to the terminal post 1) of the reset time switch 41. The terminal post e of the total cycle time switch 46 is connected by means of a line'14 to the terminal post 11 of the discharge door time switch 25.

Referring now to the dry mixing time switch 45, the terminal post 0 is connected by means of a line 15 to the terminal post 0 of the batch gate time switch 1. A line 16 also connects the terminal post 0 of the time switch 45 with the terminal postc of the discharge door time switch 25. The terminal post d of the time switch 45 is connectedby means of a line 11 to the terminal post 0 of the water time switch 33.

Referring to the water time switch 36, the terminal post e is connected to a line 18, which also connects up with the solenoid valve 54. Referring to the discharge door time switch 25, the terminal post e is connected by means of a line 19 to the solenoid valve 52. The solenoid valve 53 is connected by means of a line 80 to the terminal post e of the batch gate time switch 1.

Connected to the terminal post 0 of the time switch 41 is a line 8|, the other end of which is connected to the third terminal of the main switch 48.

By means of the improved control casing or board 8 connected with the various mechanisms forming part of the sand reconditioning system, a selective master timing arrangement is provided whereby the machine may be operated automatically for production control or said machine may be converted into a hand-controlled system by selected operation of the main switch 48.

The improved automatic control for the mulling and mixing cycle, together with the means for determining the amount of water to be added to a sand batch in order to obtain the required moisture content in the sand being mixed, assures uniform and properly conditioned sand to be discharged from the mixing crib I3 for delivery to a foundry mold forming zone.

Before the operation of the machine is started, a required quantity of sand which is to be reconditioned is measured off in the supply hopper I, which holds the batch or charge of sand in check by means of the closed batch gate 2. The threeway main control switch 48 is normally open. When an operator desires to start the automatic cycle of operations, the switch 48 is thrown into contact with the switch terminal 51. This throwing of the switch to the automatic switch contact 51, starts the cycle of operations at the line A shown in the cycle diagram of Figure 2, with the total cycle time switch 46 having the time dials thereof first set to determine the length of the entire cycle of operations. At the start of the cycle the discharge doors of the crib I3 are closed so that the first stepin the cycle is the operation of the discharge door time switch 25 to cause the discharge doors of the crib I3 to open, as indicated by the radial line A of the cycle diagram of Figure 2, allowing the discharge of a fully reconditioned batch of sand to take place from the mixing and mulling machine crib. The discharge door time switch 25 has the compound dial thereof set allowing a definite period of time for the discharge doors to remain open to permit a complete emptying of the crib. When the radial line B in the cycle diagram is reached, the discharge doors are automatically closed by the fluid pressure cylinder units 2|, and at the same time the batch gate control time switch 1 causes the fluid pressure cylinder unit 4, to operate, to open the batch gate 2 of the hopper I, permitting a predetermined charge contained within the hopper to be delivered into the crib I3. With the delivery of a batch of sand into the crib I3, the dry-mixing period commences and continues for a predetermined period up to the radial line D.

As soon as a batch of sand is delivered into the crib I3, an attendant of the machine delivers the required dry ingredients into the crib, so that the added ingredients may be thoroughly mixed and mulled with the batch of sand.

During the time that the batch of sand, which is to be reconditioned, flows from the supply hopper I into the crib I3, the attendant must determine the percentage of moisture content of the sand so that the required amount of water may be added to the mixture at a proper time, in the cycle of operations. The attendant therefore brings the moisture tester unit into play by manually swinging the air pressure control handle 36 to cause the air pressure cylinder mechanism 32 to actuate the angle-shaped sand trapping or snubbing head. 33 'to cause the sameto slide'over the testing pocket or cellp3| to trap a sample of the sand in the cell 3 1. Followingthe swinging of the handle 36 the control handle 40 is oper ated to cause the air cylinder 31 to move the compression or ramming head 38. into the closed cell 3| to compress or ram the trapped sample of "sand, thereby permitting the brass electrodes 4| to measure the pmoisturepontent Qof .the trapped sample of sand, by-the impedance principle by means ;of thegmoisture meter 44, which is connected with the electrodes 41- by means of the wires 42 and 4.3 and is:set torecord either in terms of percentage of moisture in the sameor gallons of liquid to be added "tothe batch. The attendant of the machine is thus ableto determine the quantity of Water. which is required to be added to the dry mixture within the crib l3.

The water control time switch 38 is. accordinglyset by the attendant so that at a predeter mined time in the cycle ofoperations namely, at the radial line D, in the diagram of FigureZ, the water valve 28 is opened, allowing a predetermined quantity of wateror other liquid to be delivered by the pipe 21 into the funnel 2 6 for mainder of the cycle from the radial line Econtinuously around to the radial line A, when the reconditioned batch thusprepared is discharged from the machine- Just prior to the opening of l the discharge doors of the crib I3 the radial line F indicates the time at which the reset time switch 41 is brought into operation to automatically cause resetting of the various time switches so that the next cycle of operations of the machine may take place.

In operating the moisture tester by means of the hand levers 36 and 40, the hand lever is operated to cause the snubbing head 33 to first move into position with respect to the cell 3| and to remain there while the handle 40 is operated to actuate the ramming head 38 to compress the trapped sand. As soon as the reading on the moisture meter 44 is obtained the handle 36 is released or reversed to retract the head 33. The pressure in the cylinder 31 accordingly acts to permit the continuation of the movement of the snubbing head 38 through the cell 3| so that the trapped sample of sand is discharged from the cell with the retreat of the member 33.

Attention is also called to the fact that when the dry ingredients are admitted into the crib 13 after a batch of sand has been delivered from the hopper I, such dry ingredients may either be manually dumped into the crib or the same switches. and in turn control the opening and closing of the crib doors, the" batch gate "and the addition of water, by means of the push button switches 49, 50 and f5l, which are readily accessible fromthe controlboard '8. i

In the manual. control of the machine the moisture tester may be operated by means of the control levers 36 and .40 to determine the mois ture content of the sand and the amount of water to be added, may be done bymanually operating the water valve 28 1 and the meter connected therewith... 1 l H In both the "automatic and the manual opera-. tions of the sand reconditioning system it is not necessary to operate the moisture testing control mechanism and the moisture meter "connected therewith, with the reconditioning of each batch of sand. The moisture testing is-only necessary at selected intervals and shouldzbezdetermined by the attendant operating or working the machine. It is up to the attendant-todetermine when the moisture tests should bemade and how many batches can be run on the same moisture setting.

The equipping of said 'mixing :and mulling machines with a time master unit permitting either automatic control of the various mechanisms of the machine, or manual control when desired, provides a continuous sand reconditioning system 'which is idependable vforrcontrolling the production and uniformity of foundry system sands; 1

In addition to providingrthe sand reconditiom ing machine with a time master for either automatic or hand control, a moisture content tester treatment of is also included for determining the amount of position from the sand reconditioning machine to permit remote control of the operation of the various parts of the machine, either automatically or manually, depending upon the operation of the main control switch 48.

It will of course be understood that various details of construction may be varied widely without departing from the principles of this invention, and it is, therefore, not the purpose to limit the patent granted herein otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. Means for reconditioning foundry sand comprising in combination a casing containing power-operated mixing and mulling means, a source of foundry sand, a first valve means interposed between said source and said casing to control flow of sand from said source to said casing, water supply means including a second valve means to supply water to said casing, timed means arranged operable to automatically operate said first valve means, said power-operated means and said second valve means in timed relation to each other and for predetermined periods of time, means interposed between said first valve means and said casing to indicate the moisture content of the sand flowing from said source, and manual means operable at will and cooperable with said timing means to condition the supply of water to said casing in accordance with the information on moisture content conveyed to the operator by said moisture-indicating means.

2. Means for reconditioning foundry sand comprising in combination a casing containing power-operated mixing and mulling means, a source of foundry sand, a first valve means interposed between said source and said casing to control flow of sand from said source to said casing, water supply means including a second valve means to supply water to said casing, timed means arranged operable to automatically operate said first valve means, said power-operated means and said second valve means in timed relation toeach other and for predetermined periods, means interposed between said first valve means and said casing to trap a sample of the sand, means to indicate the moisture content of the trapped sample, and manual means operable at will and cooperable with said timed means to condition the supply of water to said casing in accordance with the information on moisture content of the sample conveyed to the operator by said moisture-indicating means.

3. Means operable in repetitive cycles for reconditioningfoundry sand, said means comprising in combination a source'of foundry sand, power-operated mixing and mulling means, a first valve means interposed between said source and said mixing and mulling means to control flow of sand from the source to said mixing and mulling means, water supply means including a second valve means to supply water to the sand being mixed, a third valve means to control discharge of reconditioned sand from said mixing and mulling means, timed means arranged operable to automatically operate said first valve means, said power-operated means, said second valve means, and said third valve means in timed relation to each other and for predetermined periods of time for repetitive operation of said valve means and said power-operated means in operative cycles, means interposed between said first valve means and said mixing and mulling means to indicate the moisture content of sand flowing from said source, and manual means operable at will and cooperable with said timing means to condition the supply of water during only a predetermined portion of each cycle of operation in accordance with the information on moisture content conveyed to the operator by said moisture content indicator.

4. Means operable in repetitive cycles for reconditioning sand, said means comprising in combination a casing containing power-operated mixing and mulling means, a first valve to control discharge of conditioned sand from said casing, a hopper disposed above said casing, a second valve operable to control flow of sand from said hopper to said casing, means interposed between said second valve and said casing to indicate the moisture content of sand flowing from said hopper to said casing, water supply means including a third valve to supply water to said casing, timed means connecting said power-operated means, said first valve, said second valve, and said third valve for automatically efiecting operation of said power means and said valve means in timed relation to each other in operative cycles, and manual means operable at will and cooperable with said timed means to condition the supply of water during only a predetermined portion of each cycle of operation in accordance with the information on moisture content conveyed to the Operator by ALFRED C. CHRISTENSEN.