US2259768A - Core making machine - Google Patents

Description

Oct. 21, 1941. 'w. E. NAYLOR ETAL 2,259,768

CORE MAKING MACHINE Filed May 9, 1940 4 Sheets-Sheet l Oct. 21, 1941. w A 0 AL 2,259,768

CORE MAKING MACHINE Filed May 9, 1940 4 Sheets-Sheet 2 as v I Oct. 21, 1941. w. E. NAYLOR ETAL CORE MAKING MACHINE 4 Sheets-Sheet 3 Filed May 9, 1940 ZZZ 2.5

Oct. 21, 1941. w. E. NAYLOR ETAL 2,259,768

CORE MAKING MACHINE Filed May 9, 1940 4 Sheets-Sheet 4 Patented Oct. 21, 1941 CORE MAKING MACHINE Walter E. Naylor, Chicago, and Alfred V.

Magnuson, Berwyn, 111., assignors to Champion Foundry and Machine Company, Chicago, 111., a corporation of Illinois Application May 9, 1940, Serial No. 334,118

11 Claims.

This invention relates to machines for making sand cores, and more especially to machines of that type in which the sand that forms the core is blown into the core-box or mold by air under pressure. These machines are usually provided with an air chamber and a movable sand transfer member which carries a charge of sand at least sufficient to make the core from a supply hopper to a position in alinement with and between the air chamber and the core-box or 'mold. The core-box or mold is usually supported on a table or platform that is raised by a pneumatic liftto carry the core-box into tight engagement with the lower end of the sand. transfer member and force the upper end of the latter into tight engagement with the air discharge port of the air chamber. From the sand transfermember the sand is blown into the core-box and packed therein by the air and sand under pressure. The jack is then lowered, and the core-box and core removed.

An important object of this invention is to provide an improved air operating and control system for a machine of this character by which, through the manipulation of a pair of hand levers, the machine is first primed for the sand blowing operation, and then the several valves which admit and shut off air used in the sand blowing and lift operating operations and certain controls for said valves are all automatically operated in correctly timed order.

Another object, aum'llary to the above, is to provide, as an element of the said air operating and control system, an improved device for both distributing and timing the fiow'of air in correct order and sequence to the several air operated parts of the system.

After the sand has been blown and the main blow valve closed, considerable residual air pressure remains in the air chamber, sand transfer member, and core-box and core; and another object of the invention has been to provide an automatic device for venting this residual air pressure to atmosphere to prevent possible injury from flying sand to both the sand core and the operator, when the core is drawn.

In pneumatic jacks heretofore used, when the jack is lowered to permit removal of the core, the compressed air used to elevate the jack has been vented to atmosphere and wasted. Still another object of the invention has been to provide an improved pneumatic lift or jack for machines of this character by which this waste can be largely prevented; this being particularly useful and savto a lesser extent, when using divided or two-piece core-boxes of different heights.

Still other objects and attendant advantages of the invention will be apparent to persons skilled in the art from the following detailed description of an approved embodiment of the invention shown in the accompanying drawings, in which- Fig. 1 is a front elevation of the machine,

10, showing the pneumatic core box support in fully lowered position.

Fig. 2 is a vertical section.

Fig. 3 is a vertical section through the pneu-.

matic liftingdevice, a divided or two-part core box, the sand transfer member, and the sand blower, showing the parts in working position.

Fig. 4 is a vertical section through the pneumaticlifting device, a one piece core box, and the lower portion of the sand transfer member.

Fig. 515 a vertical section through an air distributor and timer, three pneumatically operated air flow control devices respectively associated with the main blow Valve and its chamber, the air chamber, and the core box lift, and operated in succession by the air distributor and timer, and

a manually operated air flow control device that controls the flow of pressure fluid to and from the motor of the air distributor and timer.

Fig. 6 is a fragmentary elevation of the upper end portion of the air distributor and timer,

. viewed online 6-45 of Fig. 5.

Referring to the drawings, the frame of the machine comprises mainly a pair of side frames Ill of the general type of a punch press frame spaced substantially mid-height by a transverse inverted U-shaped bar I I (Fig. 2), one side wall of which merges into the top plate l2 of a base platform l3'that constitutes a support for the core box lifting and lowering device, later described.

40 Surmounting the side frames lo and bolted to the latter isa hood l4 that extends rearwardly somewhat beyond the rear of the side frames i0, and itself constitutes a support for a sand hopper I5 and the casing l6 of the sand blow valve and its associated parts.

In the lower portion of the casing I6 isformed an air chamber ll having in its top, walla port l3, with which cooperates the main sand blow valve l9 disposed in a valve chamber 25! located directly above the air chamber H. ,The air chamber I! is of such width as to uniformly distribute the air over the top of the underlying column of sand to be blown. The stem of the main blow valve I9 includes a piston 2! slidably mounted in the upper reduced poring of air when using one-piece core-boxes, and, tion 22 of the casing 16. The upper end of the casing H5 is closed by a cap 23, and between this cap and the top of the piston 2| is a thrust spring 24 that urges the valve l9 to closed position. The bottom wall of the air chamber H is formed as a grid 25, and encircling the latter is an annular washer 26 of rubber or other flexible material designed to effect an air-tight joint during the sand blowing operation.

Slidably mounted on rollers 21 that are journalled on the inner sides of the side walls of the hood I4 is a plate 28 having therein an opening 29 adapted, in one position of the plate, to regis ter with the lower end of the hopper |5, as shown in Fig. 2, and in another position to register with the opening in the bottom wall of the air chamber that is occupied by the grid 25, as shown in Fig. 3. The plate 28 slidably engages with the lower side of the washer ring 26 and also with the lower edge of a sealing collar 30 that encircles the discharge end of the hopper |5. Secured to the underside of the plate 28 is a depending tubular member 3| that forms a movable sand transfer member or carrier which, when in the position shown in Fig. 2, receives from the hopper I5 a charge of sand more than suflicient to make the core, and, when in the position shown in Fig. 3, discharges a part of its load of sand under the pressure of an air blast into the underlying core-box. As best shown in Fig. 3, the bottom wall 32 of the sand carrier 3| is formed as a grid, the openings of which register with ducts 33 formed through the top member 34 of a divided core-box attached to the grid 32. The ducts 33 lead into a semi-cylindrical chamber 35 in the member 34, and this chamber registers with a mating semi-cylindrical chamber 36 in the upper portion of the lower section 31 of the core-box. As is usual in core-boxes of this type that are filled by sand introduced under air pressure, the walls of the lower section and the lower portions of the walls of the upper section contain fine ducts 38 that are too fine to pass the sand but permit the escape of most of the air, these ducts, of course, being finer than the sand admission ducts 33.

The lower section 31 of the core box rests on a platform 39 that, in turn, is mounted on and secured to the top wall of a cylinder 48. This cylinder 40 telescopes over a piston 4| that is mounted on the upper end of a piston rod 42, substantially the lower half of this rod having a screw thread 43. The rod'42 is slidably mounted in a central sleeve 44-of a stationary cylinder 45 that is mounted on and attached to the top wall of the base platform l3. Between the lower end of the cylinder 45 and the top wall |2 of the platform I3 is the flange 46 of a depending well 41,

with which the lower end of the threaded por-- tion 43 of rod 42 slidably engages. The flange 46 is attached by cap-screws 48 to the lower end of the cylinder 45, and the latter and the flange 46 are both attached to the top plate l2 of the platform by machine screws 49. Mounted on the thread 43 of the rod 42 is a nut 58 carrying a worm-wheel 5| engaged and driven by a worm 52 on a cross-shaft 53, and keyed on the outer end of the latter is a hand-wheel 54, by turning which the piston 4| may be raised or lowered relatively to the cylinder 45. A pin 55in the piston 4| extends through a hole in the top wall of the stationary cylinder 45, toprevent rotation of the piston 4| when the worm-wheel 5| is rotated'to raise or lower the piston. The lower portion of cylinder 45 is filled with oil, as indicated in Figs. 3 and 4. To steady the up and down movements of the cylinder 48, opposite sides of the latter are preferably equipped with longitudinal tubular guides 56 (Fig. l) slidably' engaged with upstanding rods or pins 51 mounted on the bottom flange of the cylinder 45.

For shifting the sand transfer member 3| back and forth between the sand hopper l5 and the blow chamber N, there is employed an air cylinder 58 that is pivotally mounted substantially mid-length thereof on a bracket 59 attached to the rear end of the hood I4. Within the cylinder 58 is a piston 60, the rod 6| of which is pivotally connected at 62 to a depending web or flange 63 on the top plate or head 3| of the sand carrier 3|. By reference to Fig. 2 it will be observed that the plate 28 is long enough to close the discharge from the hopper when the sand carrier 3| is shifted to blowing position. The means for operating this sand carrier motor will be described later in connection with the description of the. pneumatic operating system.

. Describing next the pneumatic operating system of the apparatus, 64 designates a main air supply pipe leading from a source of compressed air and communicating through a port 65 (Fig. 3) with the valve chamber 28. 66 designates a branch air pipe connected at its upper end into pipe 64 and at its lower end into a tank 61 (Fig. 2) conveniently mounted on the base of the machine frame or on thefloor beneath the crossconnecting member and suitably secured to the latter by hoops or straps 68. This tank 61 contains a supply of compressed air for operating the core box lift previously described. A conveniently located cook 69 in pipe 64 turns the air, usually at about 130 pounds pressure on and off the entire apparatus.

Describing the air supply to the sand carrier motor 58, Ill designates a. rotary valve mounted in a casing H .and formed. in its periphery with a chamber 12 that is constantly open to compressed air in the valve chamberv 26 through a pipe 13, T 14 and pipe 15. Connected into the lower side of the valve casing H is a pipe 16 (Fig. 1) and hose 11 through which air is admitted to the inner end of cylinder 58 to shift the sand carrier 3| into register with the hopper I5. Connected into the upper end of the valve casing H is a pipe 18 and hose I9 leading into the outer end of cylinder 58 for returning the loaded sand carrier 3| to blowing position. On the valve I8 is a handle which places .the valve in neutral when in the idle position shownin Fig. 1. When the handle 80 is swung upwardly as shown in Fig. 2, the sand carrier 3| is shifted into resister with the sand hopper. When-the handle 80 is swung down to the position shown in Fig. 3, the loaded sand carrier 3| is shifted to blowing position beneath the air chamber When the cook 69 has been opened, manipulation of the valve 10 thus brings a charge of sand into position for the sand blowing operation.

Associated with the core box lift is an air flow controlrunit designated as an entirety by 8| that performs the function of alternately admitting air from tank 61 to, and exhausting it from, the lift cylinder 40. Associated with the air chamber I1 is a generally similar umt designated as an entirety by 82 that has the function of maintaining the air chamber sealed to the atmosphere during the blowing' operatio'n, and venting it to the atmosphere at the conclusion of the blowing operation. And associated with the motor of the main blow valve I8 is a third generally similar unit designated as an entirety by 83, whichv has the function of alternately venting pressure from the space in the'casing 22 above the piston 2I to permit the valve I9 to open and admitting pressure to said space to close valve I9.

These three air flow'controlling units 8I', 92 and 83 are pneumatically operated, first in-the order in which they are above mentioned and then in the reverse order by a pneumatically motivated air distributing and timing device best shown in Fig. 5. This device comprises an uppervalve cylinder 84, an intermediate motor-cylinder 85, and a lower dash-pot cylinder 89 all disposed coaxially. Extending through the cylinder 85 and into the lower end of cylinder 84 and upper end of cylinder 88 is a rod 81, keyed on which in the cylinder 85 is a piston 88. On the lower end of rod 81 is a piston 89- playing through the dash-pot cylinder 99, and on the upperend of rod 81 is a piston valve formed with upper and lower heads 99 and 9I slidably engaged with the cylinder 94 and an intermediate narrow body member 92. Connected into the cylinder 84' at a point such that it at all times communicates with the annular space encircling the valve body 92 is an air supply pipe 93 that,- as shown in Fig. 1, draws its supply of compressed air from the pipeline I9. As the upper head 99 of the piston valve rises from its lowest position it successively overruns and opensto pressure fluid from pipe 93 four vertically spaced ports 94, 95, 93and 91 in the upper valve cylinder 84; and as it descends it successively overruns and opens to atmosphere the same ports in the reverse order. Communicating with the port 94 is a pilot pipe line 98, the other end of which communicates with a diaphragm chamber 99 in the control unit 8I, which constitutes an air motor for operating unit 8I. Communicating with the port-95 is a-pipe I99, the other end of which leads into a similar diaphragm chamber I9I of the control unit 82. Communicating with the port 98 is a pipe line I92, the other end of which leads into a similar diaphragm chamber I93 of the control unit 83. Communicating with the port 91 is a pipe line I94, the other end of which communicates with a plunger chamber I95, hereinafter referred to.

Formed as a lateral extension of the dash-pot cylinder 86 is an oil chamber I99 containing a body of. oil I9Ithat floods the cylinder 86.:through upper and lower ports I98 and I99 that are controlled as totheir-extent of flow by'screws H9 and III. wardly or outwardly, the speed of movement of the piston valve 99 may obviously be regulated.

Fig. 6 illustrates a duplex arrangement of ports such as 94, 95, 96 and 9'! by which the time interval between the opening of two successive ports may be varied. This consists in providing, in addition to the row of ports already described, asecond row of similar ports 94', 95, 99'and 91 in staggered relation to the ports 94, 95, 99 and 91. The idle ports are normally closed by plugs as indicated in Fig. 6. If, for example, it is desired to have a greater time interval between the opening of ports 95 and 99, the pipe line I92 may be shifted'from port 98 to port 96.

Referring next to the means for raising and lowering the piston valve 99, air is alternately admitted above and beneath piston 88 of the valve motor and simultaneously exhausted from beneath and above said piston through a pair of pipe lines H2 and H3 that communicate at one end with the upper and lower ends respectively of the cylinder. 85 andat their other ends communicate with a manually operated flow control By turning the screws III] and. I I! inunit designated as an entirety by I I4. This unit is structurally of the same general character as the flow control units 8|, 82 and 83, but the valves therein which direct and control the air flow therethrough are manually operated instead of being pneumatically operated. We may here mention that the flow control units BI, 92, 83 and H4 are all broadlyold and knowncommercial articles, and no-ciaimto-anyof them, per se, is made herein. Their struoturalifeatures will be sufficientlypointed out in the subjoined description 'of the operation of' the apparatusas a whole to render them readily understandable. The unit II4 also includes the plunger chamber I95, hereinbefore referred to, that contains a rod plunger II5-that 'is/pushed outwardly by air admitted through port 9! and pipe line I94 and shifts outwardly apivoted handle lever H9. Air is admitted to the unit 4 from the pipe line I8 when valve 79 is in the position-shown inFig. 3 by means of a pipe line II'I (Fig. 1), and in. the outwardly swung position of lever IIS shown in Figs. 1 and5, the air flows through the unit I I4 into and through the line II2 to the top of cylinder 85 and lowers the piston valve 99 to the position shown in Fig. 5. During this operation, air previously admitted-beneath the piston '88 is exhausted to atmosphere through pipe 1 i3 and the unit Ii 4. When the handle lever I I9 is swung inwardly, it reversesthe air flow through. the unit I I4 sending air through pipe II 3 to the lower end of cylinder 85 and thus raising valve 99,;and simultaneously exhausting the air above, piston 98 1 through pipe H2 and the unit. II4. I The 1 inward movement of. the handle II6 alsoforces the plunger I I5 inwardly, so that later, when the port 97 has been overrun on the rising movement of piston valve 99, the plunger H5 will be forced outwardly, pushing the lever I I6 back to its normal position. when the machine is idle.

.The flow controlunit 8| may be mounted on one oftheside frames I9, and is supplied with air from the tank 6'! by means of a pipe II8, the air flowing therefrom to the top of the cylinder 49 through a hose H9. The flow control unit 82 is mounted on the upper end. of a pipe I29 that communicates with a duct I2I (Fig. 5) leading turn mounted in the cap 23 of the casing I 9,

the lower end ofpip I22 communicating with the.spaceabove;thevalve'piston 2I. A pipe assembly I23 connects the T [4 with one end of the unit 83. The flow control unit I I4 is conveniently mounted, on theforward upper end of one of the side-frames I9. And the air distributing and time ing device comprising the axially alined cylinders 84,185 and 89 and theirassociated parts may also be mounted. on the outer side ofone of the side frames). c

Describing a cycle of operations, with the blow valve I9 held closed by the spring 24, as shown in Fig. 2, the cock 99;.is opened, which floods the valve chamber, 29 with comp-ressedair, a portion of the air flowing through pipe I3, T I4 and pipe I23 into the flow control unit 83. This unit 83 includes ashort pipe section I24, the bore of which is bridgedat I25 and has radial ports I28 and I2I on opposite sides of the bridge. andported portion of the pipe section I24 is encircled by an annular chambered valve I28 that ispressed to the position shown in Fig. 5 by a spring I29, and is moved in the reverse direction by air, pressure inthe chamber I93 acting through a diaphragm I39 anda-pair of rods I3I connect- This bridged" ing the diaphragm to the valve I28. Hence, with the last described parts in the positions shown in Fig. 5, the air from pipe I23 flows through the pipe section I24, by-passing the bridge I25 by flowing through the ports I26, the chamber of the valve I28 and theports I21, and thence through a curved duct I32 and the pipe I22 into the space above the valve piston 2 I. This air pressure above piston 2I balances the pressure beneath piston 2| and the spring 24 closes the blow valve I9.

In one side of the unit 83 is an air vent I33 to atmosphere; The valve handle 80 is then swung upwardly, which effects an outward movement of the sand transfer device 3| into register with the hopper I5. As soon as the latter has received its charge of sand, the valve handle 80 is swung down, and this reverses the motor 58 and shifts the sand transfer member back to its blowing position shown in Fig. 3.

The lower core member 31, having been positioned on the platform 39, is then raised into engagement with the upper core member 34 by the following operations. The handle lever H6 is pushed in. The unit I I4 includes two bridged and ported pipe sections and cooperating annular chambered valves located side by side each like that described in connection with the air control unit 83, and a central flow duct I34 that connects supply pipe II'I with a chamber I35. In lieu of the spring I29, the two chambered valves are connected to and simultaneously moved in opposite directions by the lever II6 through rods I36. When handle lever H6 is pushed inwardly, air from pipe II I is directed through line II3 beneath piston 88, and as the latter rises, port 94 is first overrun by piston valve 90. This, through pilot line 98, admits pressure to diaphragm chamber 99 of fiow control unit 8I, which unit is simi-. lar as to internal structure to fiow control unit 83. This admits pressure fluid from tank 61 through unit 8| and hose II9 into cylinder 40, which causes the latter to rise, close the core box sections on each other, and force the sand carrier 3I hard against the ring washer 26, making an air tight joint.

At this time the flow control unit 82, which has the same internal valve mechanism as the unit 8 I, is in the position shown in Fig. in which it vents the air chamber H to atmosphere through duct I2I, pipe I20 and a side vent I33 in unit 82. As piston valve 90 next overruns port 95, the unit 82 closes the air chamber II'to exhaust. The machine is now primed for the blowing operation.

Further rise of piston valve 80 overruns port 96. This, through pipe line I02 and flow control unit 83, vents the pressure above valve piston 2I to atmosphere through exhaust port I33, and the pressure on the under side of valve piston 2I overcomes the spring 24 and quickly opens the blow valve I9, as shown in Fig, 3. Sand in the sand carrier 3| is blown through the grid bottom of the latter and the ducts 33 of the corebox until the cylindrical chamber of the latter is completely filled with closely packed sand, most of the air entering with the sand finding vent through the fine ducts 38. As the top port 91 is overrun by the final part of the rising movement of piston valve 90, the plunger H5 is forced outwardly, returning handle lever H6 and the flow control parts actuated thereby to the position shown in Fig. 5.. This admits pressure above piston 88 and simultaneously vents said pressure beneath the piston to atmosphere through a vent opening I31 in the base wall of the unit II4,,s0

aorsayz'esv that the piston 88 begins its return travel. As port 91 is uncovered on the down travel of piston valve 90, plunger chamber I05 is vented to atmosphere through line I04. As port 96 is next uncovered, diaphragm chamber I03 is vented through line I02, and this returns the chambered valve I28 to the position shown in Fig. 5. This restores air pressure from pipe I23 to the chamber above valve piston 2I, closing blow valve I9. As port is next uncovered, this vents diaphragm chamber I M through line I00 restoring the parts of flow control unit 82 to the position shown in Fig. 5, in which the vent of air chamber I1 to atmosphere through exhaust port I33 is restored. This enables residual air pressure in the air chamber II, said carrier 3I, and core-box and core to be vented toatmosphere before the core-box is opened. Finally, as port 94 is uncovered, diaphragm chamber 99 is vented, and the chambered valve of flow control unit 8| is shifted by its spring back to the position shown in Fig. 5, venting the lift cylinder 40 to atmosphere through an exhaust port I38. Lift cylinder 40 descends carrying with it the lower section 31 of the core-box with the formed core C therein, and the core-box section 31 and core are shifted laterally along the platform 39, and the finished core removed; these operations being known as drawing the core, This finishes one complete cycle, leaving the apparatus in condition to repeat the described cycle on the next core-box. It may here be noted that the flow control unit 82 keeps the air chamber II closed to exhaust at all times except when the apparatus is idle and when the core is being drawn, the function of the unit 82 being to prevent the blowing of residual sand from the core, core-box, sand carrier and air chamber into the room when the core box is drawn.

The employment of the described core-box lifting and lowering device as illustrated in Figs. 2, 3 and 4, wherein the piston II is manually adjustable vertically to provide an air cylinder space of varying heights is of particular advantage when employing a one-piece core-box such as is typically shown at I39 in Fig. 4. When using such a core-box it is necessary to raise the latter only a fraction of an inch far enough to make air tight seals at both ends of the sand carrier 3|, and consequently there is only a correspondingly slight raising and lowering of the lift cylinder 40. Comparing Figs. 3 and 4, it will be seenthat the volume of compressed air used in the lift when the latter has been adjusted to the position shown in Fig. 4 is a very small fraction of that used when the lift has been adjusted to the position shown in Fig. 3, when handling a divided core-box; and since compressed air is expensive, the resulting economy is considerable. Also, a lesser comparative saving of compressed air can be effected when using divided core-boxes of less height than that indicated in Fig. 3, by adjusting the piston II upwardly to an extent corresponding to the lesser height of the core-box. Of course, when using a divided core-box, there must be suflicient vertical movement of the cylinder 40 to enable the lower section of the core-box to be lowered at least sufiiciently to clear the finished core from the upper section. Therefore, we regard this improvement in the core-box lifting and lowering device as of substantial value.

In'Fig. 1 we show the pipe lines I00, I02 and I04 equipped with normally open hand valves I40, HI and I 42, respectively, which may be .chamben-a pneumatic motor for both opening and repairs or ,renewal of parts when necessary,

and then restored to working position by reseating it on the platform and reapplying the fastening screws 49.

From the foregoing it will be seen that the present invention substantially simplifies the operation of this type of sand blower for making cores by reducing the manual operations required to the mere manipulation of valve 69 and th hand levers 80 and H6, even the return or outward movement of the latter being eifected automatically. We are aware that it is broadly old and known to manipulate a sand transfer device by a pneumatic cylinder; but, so far as We ar aware, the use of a pneumatically motivated air distributing and timing device such as the cylinders 84, 85 and BB and their associated parts to automatically effect in-properly timed relation and at a suitable'speed the several operations involved in blowing and drawing the core, is new, as well as the described structural improvements in the core-box lifting and lowering device. We also believe that a core blowing machine using a combination draw cylinder with an adjusting piston, which enables a machine used for drawing cores to be used also as a clamp device for vertical boxes without excessive air consumption, due to the adjusting piston, is new in the form shown and described. Hence, We do not limit the invention to the specific mechanisms herein presented but reserve all such variations, modifications and mechanical equivalents as fall within the spirit and purview of the claims.

We claim: r

1. In a core making machine of the class d..- scribed, the combination of an air chamber having a port in its top wall, a valve chamber above said air chamber, a sand blow valve in said valve chamber controlling said port, a compressed-air supply pipe communicating with said valve chamber, a pneumaticmotor for both opening and closing said blow valve communicating at one end with said valve chamber, a sand carrier registering at one end with said air chamber and at its other end with a core-box, a pneumatic corebox raising and lowering device, an air flow control unit including an air motor for operating the same and having both supply and vent functions communicating with said valve chamber and connected into the other end of said pneumatic motor, an air flow control unit including an air motor for operating the same and having both supply and vent functions connected into said core-box raising and lowering device, and an air distributing and timing device pipe-connected to the air motors of said air flow control units and having a single valve successively admitting air to the air motors of said air fiow control units and exhausting it from said air motors in the reverse order.

2. In a core making machine of the class described, the combination of an air chamber having a port in its top wall, a valve chamber above said air chamber, a sand blow valve in said valve chamber controlling said port, a compressed air supply pipe communicating with said valve and closing said blow valve communicating at one end with said valve chamber, a sand carrier registering at one end with said air chamber and at its other end witha core-box, an air flow control unit including an air motor for operating the. same'and having both supply and vent functions communicating with said valve chamber and connected into the other end of said pneumatic motor, an air flow controlunit including an air motor for operating the same connected into said air chamber maintaining .the' latter sealed during the blowing operation and venting'itto atmosphere at the conclusion of the blowing operation, and an air distributing and timing device pipeconnected to the air motors of said air flow control units and having a single valve successively admitting air to the air motors of said air flow control units and exhausting it from said air motors in the reverse order. a

3. In a core makingmachine of the class described, the combination of an air chamber having a port in its top wall, a valve chamber above said air chamber, a sand blow valve in said valve chamber controlling said port, a compressed air supply pipe communicating with said valve chamber, a pneumatic motor for both openingand closing said blow valve communicating at one end with said valve chamber, a sand carrierregistering at one end with said air chamber and at its other end with a core-box, an air flow control unitincluding an air motor for operating the same and having both supply and vent functions communicating with said valve chamber and connected into the other end of said pneumatic motor, an air flow control unit including an air motor for operating the same connected into said air chamber maintaining the latter sealed during the blowing operation and venting it to atmosphere at the conclusion of the blowing operation, an air flow control unit including anair motor for operating the same and having both supply and vent functions connected into said core-box raising and lowering device, and an air distributing and timing device pipe-connected to the air motors of said air flow control units and having a single valve successively admitting air tothe air-motors of said air flow control units and exhausting it from said air motors in the reverse order.

4. In acore making machine of the class'described, the combination of an air chamber having a port in its top wall, a valve chamber above said air chamber, a sand blow valve in said valve chamber controlling said port, a compressed air supply pipe communicating with said valve chamber, a pneumatic motor for both opening and closing said blow valvecommunicating at one end withsaid valve chamber, a sand carrier registering at one end with said air chamber and at its other end with. a core-box, an air flow control unit including an air motor for operatdevice, an air distributing and timing device pipe-connected to the air motors of said air fiow control units and having a single sliding valve successively admitting air to the air motors of said air flow control units and exhausting it from said air motors in the reverse order, said air distributing and timing device including a motor for operating said sliding valve, and a manually operated device controlling the supply and exhaust of motive fluid to and from said last named motor.

5. In a core making machine of the class described, the combination of an air chamber having a port in its top wall, a valve chamber above said air chamber, a sand blow valve in said valve chamber controlling said port, a compressed air supply pipe communicating with said valve chamber, a pneumatic motor for both opening and closing said blow valve conmiunicating at one end with said valve chamber, a sand carrier registering at one end with said air chamber and at its other end with a core-box,'an air fiow control unit including an air motor for operating the same and having both supply and vent functions communicating with said valve chamber and connected into the other end of said pneumatic motor, an air flow control unit including an air motor for operating the same connected into said air chamber maintaining the latter sealed during the blowing operation and venting it to atmosphere at the conclusion of the blowing operation, an air flow control unit including an air motor for operating the same and having both supply and vent functions connected into said core-box raising and lowering device, an air distributing and timing device pipe-connected to the air motors of said air flow control units and having a single sliding valve successively admitting air to the air motors of said air flow control units and exhausting it from said air motors in the reverse order, said air distributing and timing device including a pneumatic motor for operating said sliding valve, and an air fiow control unit having both supply and vent functions pipe-connected to said last named motor and to a source of compressed air and including a hand lever for operating the same.

6. An embodiment of the subject matter defined in claim 5, wherein the last named air flow controlling device includes a sliding plunger for returning the hand lever to starting position, and the air distributing and timing device includes a pipe connection to the plunger chamber for actuating the plunger in a direction to force the hand lever to starting position.

'7. In a core making machine of the class described, sand blowing means comprising a valve chamber, an air chamber underlying and having a port communicating with said valve chamber and adapted to register with a vessel containing sand to be blown into a core-box, a blow valve in said valve chamber cooperating with said port, a compressed air supply pipe communicating with said valve chamber, a cylinder above and open at its lower end to said valve chamber, a piston 8. In a core making machine of the class de-' scribed, sand blowing means comprising a valve chamber, an air chamber underlying and having a port communicating with said valve chamber and adapted to register with a vessel containing sand to be blown into a core-box, a blow valve in said valve chamber cooperating with said port, a compressed air supply pipe communicating with said valve chamber, a cylinder above and open at its lower end to said valve chamber, a piston of uniform diameter in said cylinder connected to said blow valve, pneumatically operated means for alternating supplying air from said valve chamber to, and venting it from, the

' cylinder space above said piston, and a spring in said cylinder constantly urging said piston downwardly to close said blow valve.

9. A core-box raising and lowering device for core making machines, comprising a piston, a depending threaded piston stem, a fixed cylinder of the same external diameter as said piston underlying the latter and having a depending tubular guide for said piston stem, a movable cylinder telescoping over said piston and fixed cylinder and'having a head adapted to seat a core-box, a nut engaged with said piston stem, a worm wheel on said nut, a manually operable shaft carrying a worm drivingly engaged with said worm wheel, means for locking said piston stem and piston against rotation, and. means for supplying motive fluid to, and exhausting it from, said cylinder.

10. A core raising and lowering device for core making machines, comprising a piston, a depending threaded piston stem, a fixed cylinder of the same external diameter as said piston underlying the latter and having a depending tubular guide for said piston stem, a movable cylinder telescoping over said piston and fixed cylinder and having a head adapted to seat a core box, a well underlying said tubular guide and receiving the lower end of said threaded stem, said well formed with an annular flange underlying and fastened'to the lower end of said fixed cylinder, a nut engaged with said piston stem, manually operable means for rotating said nut, means for locking said piston stem and piston against rotation, and means for supplying motive fluid to, and exhausting it from, said cylinder.

11. In combination with the subject matter defined in claim 10, a machine frame platform, and

WALTER E. NAYLOR. ALFRED V. MAGNUSON.

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