US2174847A - Casting press - Google Patents

Description

oct. 3, 1939.

T. F'. STACY ET AL CASTING PRESS Filed Oct. 19, 1957 5 She-etS-Sheet 1 Oct. 3, 1939. T. F. s'rAcY Er AL 2,174,847

CASTING PRESS 3 Sheets-Sheet 2 Filed oct. 19,- l19:5?

ATTORNEYS` Oct. 3,-193g T. F. s'rAcY E'r AL CASTING PRESS Filed oct. 19, 1957 3 Sheets-Sheet 3 NTORS. @7- *x1-Mw,

. ATTORNEYS Patented Oct. 3, 1939 UNITED STATES PATENT-` oFFlcE CASTING Pmiss Thomas F. Stacy, Piqua, Ohio, and JohnzE. Hoy, Midland, Mich., assignors of one-half to The French Oil Mill Machinery Co., Piqua, Ohio, and one-half to TheDow Chemical Company, Midland, Mich., a corporation of Michigan Application october 19, 1937, serial No. 169,808

Claims. A

'I'his invention relates to casting presses of the type in which a casting material is injected in liquid form, such as molten metal, into suitable' 30 Another object of the invention is to provide an improved casting. press, with which the point of injection of the casting materialinto, the dies may be varied to some extent for different types of jobs, with which the castings may be produced with a minimum of ash at the junctions between the die sections, with which the castings may be ejected or loosened in the dies in a simple manner, automatically, upon the separation of the die sections, and which will be relatively simple,A convenient, rapid in operation and inexpensive. i 'v Another object of the invention is to provide an improved casting press, with which an accumulator may be used as the sourceof power for producing the injection of the liquid casting material into the dies in order to obtain maximum.

,speed of injection, with which the die sections may be closed and held together in a simple, rapid and practical manner, with which the-in- `30 jecton of the castingliquid may be effectivelyl prevented until the pressure holding the die sections together exceeds a predetermined minimum pressure, and with which the separation of the die sections under the injection pressure will 35 be reduced to a minimum and substantially prevented, with consequent reduction in the forma-l tion of flashon the castings at the junction between the die sections.

-Other objects and advantages will be apparent 40 .from the following description of an embodiment of the invention, and the novel features will `be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings:

45 Fig.` 1 is a side elevation of a metal casting press constructed in accordance with this invention;

Fig. 2 is a plan of the same; Fig. 3 is a longitudinal sectional elevation 50 through the same,I with intermediate portions removed and the injection cylinder broken Aoi in order to reduce the over-al1 length of the gure;

Fig. 4 is an elevation of a portion of the same, 'the view being taken approximately along the 5 une 4 4 of Fig. 3 to show the endof the injection device and-its engagement with the pressure head by which limited adjustment of the injection device may be obtained; 60 Fig. 5 is a sectional plan of the interlock for the press, the section beingl taken approximately along the line 5-5 of Fig. 1;

Fig. 6 is a transverse sectional elevation through the interlock, the section being taken approximately along the line 6-6 of Fig. 5;

Fig. ,7 is a View similar to Fig. 6, but with the parts in a different operative position, such as when the pressure holding thedie sections together is sufficiently high so that it is safe to cause an injection of the casting 'material into the die sections;

Fig. 8 is another sectional elevation through Y ther interlock, the section` being taken approximately along the line 8-.8 of Fig. 5;

Fig. 9 is a view of aportion of Fig. 8, but with the parts in the positions taken during the injection of the casting material or metal into the die sections; and

Fig. 10 is a schematic diagram illustrating the controls for the press and the manner in whichI the interlock functions.

In the illustrated embodiment of the invention the improved casting pressl is illustrated as of the type utilizedj for the production of metal castings andv particularly for the production of magnesium castings. The improved press incluides a main base I0 witha pressure head II extending uprightly therefromz A ram base I2 is secured in any suitable manner to the main base I, but is illustrated as adjustable along the main base I0 and may be suitably anchoredl in different adjusted positions. This ram base I2 contains a ram cylinder I3, Figs. 1 and 3, in' which a main ram I4 reciprocates as usual in,

hydraulic presses. Secured to the outer end of the ramy I6 is a platen I5 which is reciprocated v toward and from the pressure head II in a manner common in hydraulic presses.

Complementary die sections I6 and I1 are secured to the platen I5 and pressure head II respectively,"- and when these die sections are brought together in abutting face to face relation they form a die in which the casting occurs. 'I'hese die sections are secured to the opposing faces of the head II and the platen I5 in any suitable manner such as is common in the mounting of dies on hydraulic presses or in casting presses.v 'I'he die section I-1, which is secured to the pressure head, is provided with' an inlet passage or gate I8 which isv in communication with one end of a chamber I9 in an injection nitely prevents the cylinder or shell-20 from` being forced endwise through the pressure head II and away from die section I1 by the reaction of the casting materials forced into the die sections.

In the form illustrated, the cylinder or shell 20 is tubular with a chamber or passage I9 that runs from end to end therethrough and is preferably cylindrical in shape. The gate or passage I8 in the die section I1 opens into the chamber I9 at the upper edge thereof, so that when the liquid casting material or molten metal is placed in the chamber I9, preparatory to injection into the die sections, it will remain within the passage I9 until forced out in a manner to be explained vpresently and will not drain out preliminarily through the gate I 8. Reciprocating vin the outer end of the chamber I9 is an injection plunger 24 which is connected at its outer end to a yoke 25. The yoke 25 in turn is connected to a piston 26 which reciprocates in one end of a ram cylinder 21. The yoke 25 reciprocates on sleeves 28 which are provided on strain rods 29 that tie alaterallyextending anchorage block 30 on the cylinder 21 to the pressure head Il.

The pressure head II is provided with undercut, vertically extending slots 3| in which anged ends or heads 32 of the strain rods are received, with the Shanks of the rods passing through the faces of the slots and with the heads 32 running in the undercut portions of the slots. The block 30 is supported through a plurality of separate, removable shim plates 33A upon a bracket arm 34 projecting upwardly from the main base I0. By varying the number of shim plates 33 between the bracket 34 and the anchorage block 30 of the cylinder 21, the cylinder 21 may be adjusted vertically to diierent extents, and by loosening the strain rods, theymay be also adjusted vertically through a sliding of the heads 32 along the slots 3l so as to set the metal injection device and its actuating elements in different adjusted levels or positions above the base I0. Thus the injection passage I9 may communicate with a gate I8 selectively placed at different 'heights 'above the base I0 as may be necessary for different types of casting jobs. cylinder 20 of course moves vertically with the ,vertical adjustment of strain rods 29 andcylinder 21, such adjustment being possible by reason of the vertically elongated'slot 2I.

The cylinder 20 has a chargingopening 35 in its upper wall immediately in front of the inner end of the injection plunger 24 when the latter is in its outer or retracted position, as shown clearly in Fig. 3. Thus, when an actuating pressure is applied to the cylinder 21 in a direction tending tp'e'ject the ram. piston 26 therefrom, the yoke 25 will be operated toward the head II and thus the injectionvram 24 will be forced along the passage or chamber' I9 so as to eject therefrom and through the gate I8 into the die sections, a liquid casting material which has previously been placed in the chamber or passage I9. Thus at the start of each operation, the liquid casting material or metal is poured into the chamber or passage I9 throughthe charging opening 35, and then the reciprocationof the plunger 24 will force this vcasting material through the gate I8 into the die sections,.after which the plunger 24 is retracted by a reverse operation of the ram piston 26.

The cylinder 21 and piston 26 together form a double action hydraulic ram and, as such hydraulic ramsare well, known in the art, they need little description. The end piston 26, which is within the cylinder 21, is provided .with a pisvmounted a knock-out bar 41.

The

at the other end through a pipe 31 which opens` into the cylinder at the anchorage block 30.

The piston I4 which reciprocates in the cylinder I3 forms with the cylinder I3 a double-acting type of ram which positively advances and retraots the platen I5. The end of the piston I4 within the cylinder I3 is provided with a piston head 38, Fig. 3, which may have piston rings 39 acting between its periphery and the inner wall of the cylinder I3. The outer end of the cylinder I3, through which 'the piston I4 passes, is normally closed by a suitable packing gland or device 40, as usual in hydraulic rams. The inner end of the piston I4 is provided with an annular recess 4I which telescopes over a tubular iiange 42 projecting axially of the cylinder from an anchorage base secured to the inner end Wall of the cylinder in any suitable manner. tral stem of the piston I4 which telescopes within the iiange 42 may also be provided with a piston head 43. A pipe 44 opens through the end of the cylinder I3 into the space within the annular flange 42, and another pipe 45 opens through the end of the cylinder I3 into the space around the outside of the annular ange 42.

The platen I is provided with a vertically ex.- tending cavity or passage 46 in which is loosely Work-ejecting pins 48 extend through the platen I5 from the knock-out bar 41 into the die section I6. Knockout pins 49 extend from the knock-out bar 41 through the platen I5 towards the ram base I2 and into position toA engage against the base I 2 when the platen is retracted into the position shown in Fig. 3. When the platen advances into die-closing position, the knockout bar 41 and knock-out pins 49 will move with it, and the pressure ofthe injected casting material within the die sections will force the pins 48 in a direction out of the die sections I6, and thus will force the knock-out bar 41 rearwardly. This, in turn, will force the knock-out pins 49 rearwardly to a corresponding extent. When the knock-out bar 41 is in its rearmost position, that is, abutting the side wall of the slot 46 nearest the cylinder I 3, .the ends of the ejecting pins 48 will be ush with the inner wall of the die cavities in the section I6. Other means, such as springs, may also be used to urge the .bar 41 and pins 48 and 49 to wards the cylinder I3. After each casting operation, the platen I5 is retracted, and as it approaches its retracted position, the pins 49 will engage with the ram base I2 and be moved endwise so as to shift the knock-out bar 41 horizontally across the slot 46, and this will in turn force the pins 48 into the cavity of the die section I6 and thus loosen or eject the work or castings from the die section I6.

Referring now to the schematic diagram shown in Fig. 10, the manner in which the activities of the pistons I4 and 26 are controlled will be described. The pipe 44 which leads to the cylinder within the flange 42 is connected to a port 56 in The centhe casing 5I of a manually operated four-way 75 valve. In the casing 5I is a spool-shaped valve element 52 which reciprocates along the cylinder 5I. One flange of the spoolv is adapted to cover and close the port 50 when the element 52 is in an inter-mediate position, and to uncover it when shifted into the end positions at opposite sides thereof. A continuously operating, variable delivery type of pump 53 is connected at its intake side through a pipe 54 to a reservoir 55 from which it withdraws operating liquid, and at its outward side the pump 53 is connected by a pipe 56 to a -port 51 in the valve casing 5I at a point between the flanges of the spool-shaped valve element 52. 'A branch of the'pipe 56 also extends to the cylinder I3 at the end adjacent the gland 40. n

The ange 58 of the valve element 52 which covers the port 50 is cylindrical in shape, so that .when it is in alinement with the port 50 it effectively closes that port, but the other ange 59 of the valve element 52 is provided at its periphery with oppositely bevelled faces 60. The inner wall of the casing 5l, in alinement with the bevelled flange 59 when the flange 58 closes the p ort 50, is provided with an annular groove 6I, and a pipe 62 leadsfrom the annular groove 6I to the pilot cylinder 63 of a pilot-operated check valve 64. The cylinder 5I, at its ends, is provided with exhaust ports 65 and 66 which are connected by a pipe `61 to the tank 55. Thus, the operating liquid withdrawn from the tank or reservoir 55 through the pipe 54 by the pump 53, will be delivered through the pipe 56 partly to the outer end of the cylinder I3 and partly to the port 51,

and thence to the space between the flanges of the spool-shaped valve element 52.

The valve element 52 is shown in Fig.`10 as in f its intermediate position, and it maybe shifted in either direction therefrom by means of a lever 68 which is pivoted at 69 to the valve casing 5i. At an intermediate point, the lever 68 is connected by a` lost motion connectiomsuch as a pin l and slot connection, indicated by the reference 10, to a stem 1I projecting from the valve element 52 outwardly through a suitable packing gland 12 in the valve casing 5I. Suitable means such as a spring-operated detent 13 that engages in notches 14 provided along the stem 1I, is employed for releasably locking the valve element 52 in any of its three positions of reciprocation in the valve ccasing 5I. The pipe 45. which leads to the closed end of the cylinder I3 exteriorly of the ange 4 2 is .connected to the check valve 64, and this check valve 64 is also connected by pipe 14 to the reservoir or tank. 55. With the valve element 52 in the intermediate position, shown in Fig. 10, and with the pump 53 operating, the liquid from the pump 53 will be conducted through the pipe 56 to the outer end of the cylinder i3 and also to the port 51 of the valve casing 5I.

From the port 51 the liquid may pass around the bevelled flange 59 of the valve elem-ent 52 and thence throughport 66 and pipe 61 back to the tank 55. Because of this free passage back to opening to pass liquid towards the cylinder I3,

but it may be forcibly opened also'when liquid is delivered under pressure to the pilot cylinder 63.

This type of check valve is disclosed, for exam- ,the inlet port 51.

ple, in United States Patent No. 1,765,627 issued June24, 1930, to Thomas F. Stacy, to which reference may be had for a more complete disclosure. There will be no material pressure in the pipe 62 or pilot cylinder 63, at this'time, because they are open to the port 66 leading' back to the tankv 55. The flange 58 of the valve element 52 closes the port 50, and thus escape of liquid from the cylinder I3 within the 'ange 42 by means of pipe, 44 is effectively prevented.

The piston I4, therefore, remains in idle, re-

tracted position' and the pump operates to cirthe piston I4, the detent 'Il is retracted and the valve handle 68 depressed, which shifts the valve element 52 downwardly in Fig. 10 until the ange 58 uncovers the port 50 and the bevelled flange 59 y moves out of alinement with the groove Gland occupies a position between the groove 6I and This interrupts communication'between the ports 51 and 66, so that the liquid delivered by the pump can no longer pass idly back to the tank 55 through thepipe 61. The delivered liquid entering the casing 5I through the port 51 will thus pass through the port 50 and pipe 44 to the closed end of the cylinder I3 within the flange 42,'and will there exert a pressure on the small piston head 43, which is a reduced projection of the piston I4. The pipe 62 -will remain in communication with the port 66 and thus no pressure will be exerted on the pilot cylinder 63, and the check valve 64 will remain a freely operating check valve.

Sdme ofthe liquid delivered by the pump will also pass through the pipe 56 to the outer end of the cylinder I3 and it will exert in the peripheral chamber around the piston I4 and against the head 38 a pressure tending to force the piston I4 into the cylinder I3, while at the same time the liquid delivered through the pipe 44 to the closed end of the cylinder I3 will exert on the section 43 of thepiston I4 a force tending to move the piston I4 outwardly `of the cylinder I3. The end area of the section 43 of the piston I4 is greater than the annular area exposed on 'the head 38 facing that end of the cylinder I3 through which the piston I4 extends, an'd thus the pressure differential on piston I4 will force it, outwardly and cause an advancing movement of the platen I5.

- vancing piston I4.

This provides a relatively rapidadvance for the platen I5, but just as the die sections are about to close with one another, a rod 15 adjustably carried by the platen I5 will engage and operate a valve 16. For example, the rod 15 may be provided with a head or flange 11 which engages with' one of the arms of a forked handle 18 of the rotary valve element 19 of the valve 16, and rotates the valve element in a direction to connect the pipe 44 to the pipe 45. The liquid delivered through the pipe 44 will now divide' and part of it will pass through the valve 16 and pipe 45 to the closed end of the cylinder exteriorly of; the flange ,43, so that the liquid delivered under pressure by the pump will now be exerted on the entire end of the piston I4 at the closed end of the cylinder I3. When this happens, the pressure on the liquid in pipe 45 automatically closes the valve element 84a of the check valve 64 to prevent direct return through the pipe 14 of any of this delivered liquid. The platen I5 will then have continued movement in the same direction but at a slower rate, because of the fact that the operating liquid delivered through the pipe 44 must now be spread over a greater piston area. When the die sections meet, the resistance will mount rapidly and build up the holding pressure on the die sections.

The pump illustrated is of the continuously operating, variable delivery type, which automatically sets itself to'approximately neutral delivery when the pressure on the piston I4 reaches or exceeds a predetermined minimum pressure. Such pumps are well known in the art and are disclosed, for example, in United States Patents Nos. 1,578,233 and 1,077,979. In this type of pump the rate of delivery is varied by shifting a yoke 8U, and this yoke may be shifted by a lever 8| which is pivoted at 82 to a suitable part of the motor frame. The lever 8| is also connected by a pivot pin 83 to a link 84 which has a flange 85 at its fre'e end.- A rod 86 passes slidably through an aperture in the flange 85 and carries at one end thereof a shoulder or head 81. .A spring 88 is provided on the rod 88 under compression between the head 81 and the flange 85, so as to urge the lever 8| in a clockwise direction in Fig. 10. Thev rod 88 passes slidably through a ilange 89 of the motor frame, and is there threaded and provided with a hand wheel nut 98. Thus, by turning the Wheel or nut 90, the rod 86 may be drawn through the flange 89 to different extents, and thus the pressure on the spring 88 Varied.

The spring 88, acting through the link 84, tends to rock the yoke lever 8| in a clockwise direction, Fig. 10, and thus shift the yoke in a direction to provide for maximumdelivery of the pump. An auxiliary or delivery controlv cylinder 9| is also provided on the pump frame and a small ram 92 reciprocating in the cylinder 9| extends outwardly into abutting relation with the yoke lever 8| in a manner to oppose such clockwise movement of the lever 8| as is caused by the spring 88. A pipe 93 connects the other end of the cylinder 9| with the pipe 45 which leads to the closed end of the cylinder exteriorly of the flange 42. Thus, when the pressure on the piston I4 builds up after the die sections have closed, this rapidly increasing -pressure is transmitted through the pipe 93 to the cylinder 9| of the pump, and when the pressure is suiicient to overcome the spring 88, the piston 92 will be forced outwardly to some extent andwill rock ythe yoke lever 8| counterclockwise inFig. 10, andy shift the yoke 88 in a` direction to cut down the rate of delivery of the- As the pressure continues to mount, the rate of delivery of the pump will be further cut down, and when -the maximum pressure determined by the spring 88 is reached, the pump will have been set approximately to neutral delivery condition.

Thus, the pressure will be maintained automatiback tothe tank 55 through the pipe 94. The pump will maintain this maximum pressure on the piston I4 and thus on the platen to hold the die sections closed as long as desired, which will be until the casting material has been injected into the die sections. The operator then sets the valve element 52 to cause a retraction of the platen I5. To do this the spring detent 13 is rst retracted and the valve lever 68 is then shifted in the opposite direction through the neutral or intermediate position shown in full lines in Fig. -10 to a position in which the flange 58 is above the port' 58 and the flange 59 of the valve element 52.is,between the groove 6I and the port 86. The spring actuated detent 13 then latches the valve element 52 in that position.

When the valve element 52 is in thisv position, the port 50 willbe connected through the lower end of the valve casing 5I with the port 85, and

Y liquid may then pass from the closed end of the cylinder I3 within the flange 42 through the pipe 44, valve casing 5I and pipe 61 back to the tank 55. The liquid in the closed end of the cylinder I3 exteriorly of the flange 42 may pass through the pipe 45, valve 16 and pipe 44 also back to the tank 55. When this pressure falls, the continuing pressure on the opposite side of the piston head 38 caused by the continued delivery of liquid from the pump through the pipe 56 to the outer end of cylinder I3 will cause retraction of the piston I4 into the cylinder I3. At the same time, some of the operating liquid under pressure delivered to the pipe 56.by the pump, which of course continues to operate, will also pass through the valve casing 5I from port 51 to the groove 6I and thence through pipe 82 to the pilot cylinder 83. liquid under pressure will then exert a pressure on the pilot cylinder 83, tending to forcibly open the free check valve element 64a, but this valve cannot open until the pressure in pipe 45 has fallen sufliciently, but such pressure will fall through escape of liquid from the pipe 45 through the valve 16 and pipe 44.

As soon as the pressure has fallen sufciently to enable the check valve element 64a to be opened, the liquid from the pipe 45 may then pass through pipe 14 directly back to the tank 55 instead of through -the valve casing 5I. Early in the return movement of the platen I5, the head'11 of rod 15 on the platen will engage the other of the arms of the forked operating handle 18 of the valve `16, and will rock the valve element 'I9 into closed position as shown in full lines in Fig. l0, thus shutting off direct communication between the pipes 44 and 45. Both pipes 44 and 45 will however drain back into the tank 55 so that the continued pressure on the piston I4 tending to retract it into the cylinder I3 will continue This the retraction of the platen. As the platen approaches its fully retracted position the knock-out pins 49 will engage the ram base I2 and through the knock-out bar 41 and work electing pins 48 will loosenthe casting or castings from the die section` I6. At this time the operator should retract the detent 13 and shift the valve handle 68 back into the position shown in -full lines in Fig. 10 which sets the valve for idle' circulation of the liquid from the pump 53. When this happens the pressure in pilot cylinder 63 will be released, and the check valve 84a will close. The platen I5 will then remain in this position until the valve handle 58 is again manipulated to start a forward or advancing movement of the platen I5.

The operation of the ram to inject the casting liquid into the dies will now be described through continued reference tol Fig. 10. The inner end of the piston 26 is provided with a piston head 95. The pipes 36 and 31 are connected to the cylinder 21 at opposite ends thereof which are at opposite sides of the piston head 95. The pipes 36 and 31 lead to intermediate ports of a pilot operated, fourwa'y valve 96 having a spool shaped valve element 91 reciprocating endwise therein. The flanges 98 and 99 of the valve element 91 occupy one extreme position, as shown by the full lines in Fig. 10, which is the maximum position to the left in that figure; A pipe |00 connects the interior of the casing 96, at points spaced along the same substantially beyond the openings fiom pipes 36 and 31, with a tank IOI which may advantageously be the'tank 55 when the same kind of `liquid is used for operating both pistons I4 and 26, otherwise they are separate tanks.

Instead of a pump for supplying the operating liquid for the cylinder 21, we prefer to use an accumulator to supply the necessary operating pressure, because an accumulator maintains the same uniform pressure and provides for a very Y rapid delivery of the operating liquidunder this maximum and uniform pressure. The accumulator |02 is of any suitable and well known type, and since accumulators are well known in the industry, a detailed description is omitted. In principle, an accumulator includes a weight-operated piston I03'which exerts a pressure on the liquid in the chamber |04, and the liquid so compressed, is conducted from the accumulator by a pipe |05, one branch I05a being connected to the valve casing 96 approximately midway between the openings of the pipesI- 36 and 31 into the casing 96. The other branch |0512 of pipe |05 is connected to a pilot control 'valve |06 which will be explained presently.

Within the casing |06 is a spool-shaped valve element |01 having anges |08 and |09 thereon. The pipe I05b opens into the casing |06 between the anges |09 and |09. Pipes I'I0 and III also open into the casing |06 at points spaced endwise inopposite directions from the inlet from pipe |051), so that the space between the anges of the spool-shaped valve element |01 will connect the pipe |0511 alternately to the pipes IIO and III as the element |01 is reciprocated in its casing. The ends of the casing |06 are connected by a pipe H2 to the tank |0I. When the valve element |01 is in the position shown in full lines in Fig. 10, it will connect the pipe |051) to the pipe III, and the latter is connected to the right-hand end of the casing 96. 'The pipe IIO is connected to the opposite end of the same casing 96 where it isy vented by pipe II2. When the valve |01 is moved endwise Vof the casing |06 towards the opposite end of that casing, the flange |08 will pass the opening into the pipe I I, and thus cut oi communication between the pipes '|0511 and III, and the-valve flange |09 will pass the opening into the pipe IIO and establish communication between the pipe |0512 and the pipe I I0 because the flange |09 will then be between the opening into pipes I I0 and I I2.

At the same time, the flange los win be disposed between the openings in the pipe |0517 and III, so that the latter pipewill be-in communication with the pipe II2. Since the laccumulator |02 delivers a constant supply of operating liquid under pressure to the pipe |05, it follows that this pressure will be transmitted lto one or the other end of the valve casing 96, depending upon the position of the valve element |01. The end of the valve casing 96 to which the pressure is not transmitted at any time will be connected with the pipe ||2 leading to the tank IOI. In the position of the parts shown in Fig. l0, liquid under pressure from the accumulator is conducted to the right-hand end of the valve casing 96. A rod II3 extends from the right-hand end of the valve element 91 toward the right-hand end of` the cylinder and terminates in a pilot piston IIII, disposed between the opening from pipe |00 and the adjacent end of the casing 96 into which the pipe III opens.

Similarly, a rod II5 extends from lthe opposite end of the valve element 91 toward the opi whenthis happens, the liquid under pressure delivered by the accumulator to the pipe |05 will be transmitted through the pipe I05a and the -space of the spool valve 91 between the anges 98 and 99 to the pipe 31, and thence to the left hand end of the cylinder 21. This pressure forces the piston 95 to the right and retracts the ram 26 to the right in Figs. 1 to 3 and 10. This1retracts the yoke 25 and the injection rod 2d into the position shown .in full lines in the drawings.

The parts remain in these positions until a rapid operation of the injection device is desired. The valve element |01 of the control valve |06 is provided with an operating rod I|1 which extends outwardly through one end of the casing |06; Figs. 5, 8, 9 and 10, whereit is connected to a latch rod IIB which forms a continuation thereof. The free end of the rod lI I8, Figs. 5 to 9,

is pivotally connectedby a pin II9 to a lever |20 pivoted at |2| on the base l0 of the machine. Thus, by stepping on the free end of the lever I20,it may be rocked from the position shown in full lines in Fig. 8 into the dotted line position shown in the same figure. When this occurs, the rods II1 and H8 `will be moved endwise so as to shift the valve element |01 downwardly in Fig. 10 into a position in which the liquid from the accumulator will be transmitted throughvthe pipe |0511 to the pipe IIO instead of the pipe I I I, and the pipe III will be. vented through pipe II2.` The accumulator pressure will then be applied to the left hand end of the casing' 96 in Fig. 10, and the right hand end of the casing 96 will be vented to the pipe I I2.

The accumulator liquid under pressure will thus pass through pipes |0511 and I|0, and acting on the pilot piston IIS, will force the valve element 91 to the right in Fig. l0. The flange 98 of the element 91'will then be disposed between the inlet to pipe 31 and that of pipe I05a. This shuts off the transfer of accumulator liquid under pressure to the left-hand end of the cylinder 21. At the Sametime the iiange 99 passes beyond the opening to pipe 36, and thus/communication is established between the flanges 99 and 99from pipe I05a to pipe 36, The pipe 31 is vented to the pipe |00, and thus the accumulator pressure now acting on the right hand end of I9 through the opening 35. When the lever |20 iso The operation of the casting press has been released, it Will be returned to the position shown in Figs. 5, 8 and 10 in any suitable manner such as by the spring |22, Fig. 10. The valve element 91 will then be returned to the left hand position shown in Fig. 10 causing a retraction of piston 26, and the parts will remain in those positions until the operator again manipulates the lever from the full to the dotted line position shown in Fig. 8. Liquid under pressure may be stored in the accumulator in any usual manner such as is'noW in common use, or it may be supplied to the accumulator through the pipe |23, and after the supply is stored therein the pipe |23 may be closed by a valve |24.

It will be observed that if' an attendant through carelessness or accident should manipulate the lever |20 and cause an injection of the casting metal or material before the die sections are fully closed with one another or held together with insuflicient pressure, a serious accident might occur through the spilling of the casting material which is usually hot. Accord'- ingly, provision is made of an interlocking safetyA device to prevent any possibility of such an accident or operation. This safety device includes a cylinder |25 provided with a piston |26. A stem |21 extends outwardly through one end of the casing |25, the other end of the casing being closed. A spring |28 Within the casing |25 acts \on the piston |26 to shift it further into the casing |25, as shown in Fig. 10. That closed end of the casing |25 is connected to the pipe 93, so

that the piston |26 will always be subjected to the pressure in the pipe 45 and hence to the pressure on the piston I4 at the closed end of the cylinder I3 but exteriorly of the ange 42. The rod |21 extends crosswise of therod I|1 and it is connected to a sliding latch block |29 having intermediate of its ends a notch |30. The block |29 extends 'beneath'the latch rod IIS, as shown inFigs. 5 to 9, and is slidingly guided by a groove |29a in the main base I0.

When the rods I|1`and |21 are in their retracted positions shown in Fig. 10, a shoulder` or abutment |3| on the lower edge of the latch rod IIB will be engaged behind the sliding latch block |29, as shown in Figs. 6 and 8. It will thus be impossible to operate the lever |20, because the engagement of the abutment or shoulder |3| with the side face of the rod |29 will prevent any such movement to initiate an injection of casting material into the die sections until the latch block |29 has first been moved` endWise until its notch |30 is brought into alignment with the shoulder or abutment |3|, as shown in Figs. 7 and 9. 'I'his movement of the block |29 into the aligned position with the shoulder |3| occurs only after the increasingprssure on the piston I4 has reached alpredetermined minimum or adequate safe holding pressure by which the die `sections are clamped together. Thus, until the die sections are clamped together with a safe holding pressure, one` cannot manipulate the lever |20 to cause aninjection of casting material into the diesesctions. At the conclusion of a casting operation, when the platen I 5 is retracted to separatethe die sections, the pressure in the pipe 45 immediately falls, as khereinbefore explained, and when this happens the pressure on the piston |26 decreases and the spring |28 returns the rod |21 .to the position shown in full lines in Figs. 6, 8 and 10 where itagain latches the rody II8 and` valve element |01 in safe position.

explained in connection with the description of the construction of the/press and its controls. It willbe noted that separate sources of pressure are utilized `for holding the die sections closed and for operatingthe injection devices, and that an accumulatory is preferably used to provide the pressure for causing the injection of the casting material. 'I'he accumulator pressure kis relatively expensive, and a considerable saving is obtained by utilizing the pump as the source of pressure for the holding pressure. Notwithstanding the use 4of the pump, however, a rapid Aclosing ofthe dies is possible and the holding pressure may be varied as necessary, depending upon the sizeof the cavities in the dies which determines, of course, the reaction pressures tending to separate the die sections.

Thus time and expense are saved by utilizing4 the adjustable delivery pump as the source of operating liquid for holding the die sections closed. It will also be noted that the work is loosened or ejected from the die sections automatically. The interlock between the two operating rams prevents any danger through premature operation 0f the device `for injecting the casting material into the die sections. 'I'he tension ofthe spring I 28 in the interlock which determines the pressure at which the casting material injection device can be operated, may be varied in any suitable manner, such as by inserting or removing shims |32 (Figs. 5 and l0) between the spring |28, and a removable block |33 fitted into the open end of the cylinder |25.

Because of the high pressures used to clamp the die sections together, it is desirable to tie the pressure head I to the ram base I2, and for this purpose strain rods |34 connect the pressure head and the ram base as usual in hydraulic presses.

kIf the platen I5 is merely ladvanced suiiiciently to close the dies and bring them in actual Contact,

. injected 'material or casting liquid will not cause any material separation of the die sections,

This preloading is accomplished by the arrangement herein described and illustrated for closing the die' sections and holding them closed under the pressure from the continuously operating, variable delivery pump. The force necessary to cause the initial stretch of the strain rods |34 is much less thanithat necessary to stretch them a given amount after they have already been stretched to a considerable extent. By

and the liquid in the advancing ram then locked reason of 'this preloading of pressure on the die sections, the "ash on the castings is substantially eliminated or reduced to a minimum.

It will be understood that various changes in the details and materials, which have been herei in described and illustrated in order to explain the nature of the inventiony may be made by those skilled in the artwithin the principle and scope of the invention, as expressed in the appended claims. I

Y ously acting variable delivery pump to operateatraer? We claim:

1. In a pressure die-casting apparatuscomprising a separable die mold, a hydraulic press to open and close the mold and hydraulically operated injecting means for delivering molten metal into the mold, a system to control the operation oi said press and said injecting means having in .combination separate hydraulic circuits for supplying working iiuid to said press and said injecting means, respectively, independently actuated valve means in each circuit, a continuthe hydraulic press'circuit, means responsive to the pressure in said press circuit to vary the rate of delivery of said pump, intermittently acting motive means including an 4accumulator connected to operate the metal injection circuit when permitted by said valve means in that circuit, a lock controlling the valve in the last men-` tioned circuit normally preventing operation thereof in a manner to cause injection of molten metal into the mold, and means' responsive to a predetermined die closing pressure in the hydraulic press circuit to release said lock and permit operation of said valve means of the injecting circuit in a manner to allow operation of said metal injecting means.

2. In a pressure die-casting apparatus comprising a separable die mold,l a hydraulic press to open and close the mold, and hydraulically cperated injecting means for delivering molten metal into the mold, a system to control the operation of saidv press and said injecting means having, in combination, separate hydraulic circuits for supplying Working iluidto said press and said injecting means, respectively, selectively operable valve means in the circuit of said injecting means for controlling the activity of said injecting means, means for supplying an.operating fluid to said hydraulic press circuit to operate the same to close and open said mold and when said mold is closed to build up and maintain a predetermined holding pressure thereon, and means separate from said supplying means for delivering a separate operating fluid under constant pressure to said metal injection circuit to cause an operation of said injecting means and an injection of metal into said mold, whereby iluid pressure may be applied separately to said'press and to said injecting means, a lock controlling said valve in the metal injection circuit and normally preventing operation of said valve' into a position in which it permits an operation oi' said injecting means and thereby an injection of molten metal into the mold, and means responsive to a predetermined, safe die closing pressure in said hydraulic press circuit tounlock said valve for movement into a position to permitan operation of the metal injecting means.

3. In a pressure die-casting apparatus comprising a separable die mold, a hydraulic press to open and close the mold and hydraulically operated injecting means for delivering molten metal into the mold, a system to control the operation of said press and said injecting means having in combination separate hydraulic circuits for supplying working iluid to said press and said injecting means, respectively, a valve in said circuit of said injecting means, a pump device connected to the hydraulic press circuit tc deliver operating uid thereto and firstclose the die mold and then build up and maintain a predetermined holding pressure thereon, intermittently acting motive means connected to the met' al injection circuit for supplying thereto an operating iluid under constant pressure throughout the operation of said injecting means and separate from said holding circuit, a lock controlling said valve means and normally preventing operation thereoi.1 into a position to permit an injection` of molten metal into the mold, and means responsive to a predetermined closure holding pressure on the mold in the hydraulic press circuit to unlock said valve means for movement into a position in which it lpermits an operation of the metal injecting means. Y

4. In a pressure die-casting apparatus comprising a separable die mold, a hydraulic press to open and close thek mold and hydraulically operated injecting means for delivering molten metal into-the mold, a system to control the operation of said press and said injecting means having in combination separate hydraulic circuits for supplying working uid to said press and said injecting means, respectively, means controlling the activity of said press circuit and thereby controlling the opening and closing of said mold, a valve in said metal injection circuit for controlling,the activity of said injecting means, pumping means connected to said press circuit to supply an operating uid thereto, close said die mold and then build up and maintain a predetermined closing pressure thereon, a separate, intermittently acting, motive means for supplying an operating fluid under constant pressure throughout operation of said metal injection circuit to cause an operation of said injecting means when permitted by said valve, a lock controlling said valve and normally preventing operation thereof in a manner to cause injection of molten metal into said mold, and means responsive to a predetermined holding pressure on said mold in the hydraulic press circuit for operating said lock to release said valve for operation in a manner to cause a casting-operation of said metallinjection means.

5. In a pressure die-casting apparatus comprising a separable die mold, a hydraulic press to open and close the mold and hydraulically operated injecting means for delivering molten metal into the mold, a system to control the operation of said press and said injecting means having in combination separate hydraulic circuits for supplying working iiuid to said press and' said injecting means, respectively, a valve in said circuit for said injecting means, a continuously acting, variable delivery pump connected to said press circuit for operating the same to close the die mold and thenv build up and maintain a predetermined closing pressure thereon, means responsive to the closing pressure in said press forvarying the rate ci.' delivery of said pump, intermittently acting, motive means connected to the metal injection circuit for supply-

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