US2145956A - Die casting machine - Google Patents

Description

Feb. 7, 1939. M. STERN DIE CASTING MACHINE Fileddune 9, 1937 6 Sheets-Sheet 1 Feb. 7, 1939. M. STERN 2,145,956

DIE CASTING MACHINE Filed June 9, 1937 6 Sheets-Sheet 2 COMP. AI

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DIE CASTING MACHINE Filed June 9, 1937 6 Sheets-Sheet 4 Feb. 7, 1939. M STERN 2,145,956

DIE CASTING MACHINE Filed June 9, 1937 6 Sheets-Sheet 5 M. STERN Feb. 7, 1939.

DIE CASTING MACHINE Filed June 9., 1937 Sheets-Sheet 6 Id? ta:

Patented Feb. I, 1939 DIE cAs'rme, MACHINE Marc Stern, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application June 9, 1937, Serial No. 147,229

15 Claims.

' number of interrelated parts upon manual initiation are active according to predetermined timing to supply fluid under pressure to the pressure responsive devices.

A further object is to provide a system designed for operation generally on relatively low fluid pressures and wherein the efiective pressures are automatically varied in certain steps of the oper- 20 ating cycle. Such variation as affecting relative motion .of the dies, for example, results in an initial slow movement, an accelerated movement in the intermediate range of travel, and a final slow movement so that the dies open and close 5 quickly and without inertia shock. Additionally, when the die is closed and is being filled with molten metal an increased pressure is built up to hold the die closed and resist separation under influence of metal injecting pressures.

30 Additional objects and advantages of the construction will become apparent during the course of the following specification having reference to the accompanying drawings wherein Figure 1 is a side elevation of the complete machine; Figure 2 35 shows the pair of pressure pumps driven by the same motor; Figure 3 is a fragmentary view, partly in section, of the metal injecting device; Figure 4 is a diagram of the control system; Figure 5 is a sectional view of the die operating cylinder; FigiO ure 6 is a sectional view of the ejector assembly showing the die in closed position; Figure '7 is a plan view of aportion of the machine; Figures 8, 9 and 10 are perspective views showing the parts which serve to initiate and cut oil? the operation,

block 8 fastened to the upright 3. The sprue opening in the die block 8, as seen in Figure 6, communicates through the nozzle 9 with the pressure chamber I suspended within the melting pot l l. The melting pot to contain fluid metal forms a part of the furnace l2 which may be fired by a.

gas burner l3 or the like. Molten metal from the .pot ll enters the pressure chamberthrough a 60 passage l4 andis forced by a slidable plunger l into the die cavity. At its upper end the plunger I5 is guided in a frame l6 and, as shown in Figure 3, is connected by a link I! to one end of a rocker l8 pivoted at I9 on the frame l6 and connected at its opposite end by a link 20 to a connecting head 2| on the rod 22. The rod 22 is joined'to the piston 23 slidable within the cylinder 24 under influence'of fluid pressure applied on opposite sides of the piston.

Upon separation of the die blocks the finished casting is pushed out of the cavity of the movable die I by an ejector pin 25 which is shown inFigure 6 as on the end of ,a rod 26 reciprocable within spacer and die supporting members 21 on the movable carriage 6. The opposite end of the rod 26 is fastened to a slider 28 fixed by a removable pin 29 to the stem 30 of a piston 3| slidable within a cylinder 32 upon the application of fluid pressure to one side or the other of the piston. The cylinder is supported upon the movable carriage 6 and the carriage is' fastened by the studs 33 to the piston rod 34 which, as seen in Figure 5, is joined to a piston 35 slidable within a cylinder 36 which. is mounted on the upright 2 and into the opposite ends thereof pressure fluid is introduced for effecting carriage reciprocation.

Fluid, preferably oil, for operating the several work performing cylinders is supplied from a reservoir 31 by a pair of pumps 38 and 39 continuously driven by an electric motor 40. The oil under pressure flows through a system of pipes and under control of certain valves puts the machine through a complete operating cycle. To initiate operation there is provided a hand lever 4| firmly held in inoperative position by a spring 42' and which lever is mounted at the side of the machine within convenient reach of the operator on a rockshaft 43 supported in suitable bearings 44. At its upper end the shaft 43 carries a cam 45 which upon manual actuation of the" shaft 43 lifts a pawl 46 about its pivotal mounting on the slide. 41 and against the flat spring 48 out of alignment with the tip 49 on a spring pressed slide valve 50 contained within the valve housing 5| on the upright 2. This allows oil under pressure to reach the ejector cylinder 32 and retract the ejector pin 25. Upon move-- lever 54-about its pivot to the position shown in Figure 11. The opposite end of the lever engages with the bar 41 and slides it to a predetermined set position for a purpose to be hereinafter referred to.

At the same time that the pawl 46 releases the tip 49, the lever 55 at the bottom of the rockshaft 43 engages the rod 56 and moves the same inwardly to shift the slide valve 51 in the casing 58 for delivering liquid under pressure to the carriage operating plunger. As seen in Figure 4 the rod56 carries a locking collar 58 which moves into engagement with a pivoted latch 60 which holds the slide valve in set position against its spring 8| until the latch 60 is released by the action of a solenoid 62. u Referring more particularly to the diagramv matic illustration of the control system and assuming the parts have been moved by the operation of the hand lever M to the positions mentioned, oil under pressure will be supplied by the pump 38 through the check valve 63 and the conduit 64 to the branches 65 and 65. The

oil flowing through the branch 65 will pass through-the valve casing 5I and through the conduit 61 to the ram end of the ejector cylinder 32. At this time the opposite side of the piston, by means of the conduit 68, is vented through the valve 5I to the drain-pipe 88 which leads back to the supply reservoir 31.

In the mentioned setting. of the valve 51 oil under pressure supplied by the branch 86 will flow through the conduit I to a valve casing II and after lifting the spring seated poppet formations thereon.

pipe 8| leading from the valve casing 82 connected with the pump 38 communicates through Means is provided to superimpose pressure from the pump 38 upon that supplied by the pump 39v during the intermediate range of carriage travel in order that the travel in this zone may be speeded up. For this purpose the carriage has secured'tliereto a strap I5 on which'.

are located spaced cam abutments I8 and 11, respectively, the latter of which maybe adjustable. In the first portion of carriage movement the cam I8 engages a roller on a slide valve I8 and moves this valve inwardly in its casing I8 against a spring 80 into position wherein. the

a pipe 83 with a chamber in the valve body 82 on the upper side of a piston valve 84 to close off communication of the pump 38 through the conduit 85' leading to the branch conduit 85. As the movement of the carriage proceeds the cam I6 moves away from the roller on the slide valve I8 and allows the valve to be projected under influence of its spring 80 to a position wherein the pipes 8| and 83 are out of communication and the pipe 83 is drained through the pipe 86. 'I'hereupon the pressure from the pump 38 will lift the piston valve 84 and oil from the pump a ing carriage.

will flow through the conduit 85 and into the conduits 65and 56 through the valve 58 and conduit I0 for action on the piston 35. As the carriage approaches die closing position the cam II engages with the roller on the slide valve I8 and again operates the valve to communicate the pipes 8I and 83 and thereby close the piston 'valve 84 whereupon the final movement is decelerated to cut down the momentum of the slid- As soon as the die is closed an angle bracket 88 or other suitable part (see Figure 1) mounted on the carriage 6 engages a button on the switch 88 to close an electrical circuit which controls the application of pressure for operating the metal injecting apparatus. The circuit includes a main line switch 80 and when both switches 88 and 80 .are closed electric current flows through the wire 8| to a relay 92 connected by the wire 83 to the return line 94. Actuation of the relay 82 allows current flow through the line 95 to a timer 96 of a well known adjustable type. The return line from the timer is indicated at 81. Thereafter for a predetermined interval electric curand back through the return line I00. Actuation of the solenoid 88 moves a slide valve IM to communicate a pressure line I02 constituting a branch of the conduit I0 with a valve cylinder I03. This causes the slide valve I04 to move toward the right in Figure 4 against the spring I 05 and thereafter the pressure line I06 leading from the gear pump 38 through the check valve I01, communicates with a conduit I08 leading to the head end of the cylinder 24, whereupon the piston 23 is lifted and the plunger I5 is depressed for injecting metal into the die. x the ram end of the cylinder 24 is vented through the conduit I08 by the slide valve I04 to the drain IIO. As soon as oil is supplied by the line I02 to the valve chamber I03 it also flows through the pipe III through a check valve I I2 to a booster cylinder I I3 for priming'the same. Concurrently with the flow of oil to the line I08 oil under pressure is also supplied through the conduit H4 and past a check valve II5 tothe booster or intensifier cylinder II3. Within the booster cylinder are interconnected large and small pistons H8 and I II, respectively, and the oil supplied through the line I acting on the large piston II6 forces oil at a relatively high pressure through the conduit H8, leading to the valve casing II.- This oil flowing across the valve I2 closes this valve and acts on the piston 35 to insure the dies being held firmly together during the pressure injection of molten metal to the die cavity.

In order that the pressure in the system may be uniform from time to time there is provided an accumulator in the form of a cylinder 8 containing a large piston I20 and a small piston I 2I and beneath the small piston the cylinder communicates through a conduit I22 with the valve casing I03 in alignment with the pressure supply line I 06. The oilcontaining portion of the cylinder, therefore, provides a reserve supply of oil which is under a predetermined pressure through the action on the large piston I20 from a suitable source of air under pressure.

After a predetermined interval the timer 85 acts to open the circuit containing the solenoid- 88 whereupon the valve IOI will be restored and vent the piston cylinder I03 through the drain pipe I23. Thereupon the spring I05 moves the slide valve I04 toward the left in Figure 4 and opens the conduit I08 to the drain pipe I24. At the same time oil "under pressure from the line I08 flows through the conduit I08 and acts on the piston 23 to restore the same. Thereafter the timer I25 having the return line I26 closes a switch between the line I21 and the line I28 and through a switch I28 supplies current to the solenoid 82, having a return line I30 for releasin the latch 60 and allowing the slide valve 51 to be restored. As a safety measure the switch I28 precludes closing of this circuit until the metal injecting plunger is fully restored and accordingly the switch blade has a roller I3I which projects into the path of and is adapted to .be operated .rent flows through the line 88 to a solenoid 88 At the same time.

by the coupling head 2|. As soon as the.valve I1 is restored oil under pressure flows through the line 13 to the ram end of the cylinder 36 for returning the carriage. At the same time the line III is vented through the drain I4 and oil under pressure flows through the pipe I32 and lifts a piston I33 in the casing II which has a stem toengage and open the poppet valve I2 for communicating the head end of the cylinder 36 with the conduit Ill. Oil under pressure also flows through the pipe I34 and acts on a piston I36 within the cylinder H3 to engage and hold open the valve I I6 so that the cylinder may be vented through'the conduit H4 and the drain pipe I24. The initial return'movement of the carriage is slow and then fast and flnally slow by reason of the engagement and disengagement successively of the cams 11 and I6 with the valve I8 as before referred to.

go As the carriage approaches the final open posi- 25 pipe I36 and oil under pressure is supplied through the branch 65 and conduit 68 to the head end of the cylinder 32 for projecting the ejector pin 26. As the piston 3i moves to its limit the rod 53 carried thereby through an adjustable collar 30 I31 strikes the adjacent end of the lever 64 and carries this back into latched engagement with the poppet I53. The'swinging of the lever 54 projectsthe pawl 46 an additional amount sufllcient "to move the valve 50 further inward to a position 35 whereby the pressure supply line 65 communicates with the drain I36. Thus in the inoperative position of the parts a continuous circulation of the pressure fluid is afforded and the reduction in resistance to pump operation avoids unnecessary 40 heating of the oil.

It will be .noted among other things, that the operating cylinder 24 for the metal injector plunger I5 is not mounted directly above the melt-' ing pot as is ordinarily the practice in die casting machines, but rather is mounted at one side.of the furnace and operates the plunger through the rocker I8. This eliminates 'a fire hazard due to oil leaks and furthermore enables access to the melting pot for replacement without disturbing the operating cylinder and its connections with the fluid pressure lines.

, to be replaced a disconnection is made in the-link' and the plunger "guide frame I6 ismoved out of interference. "For this purpose one of the ver-' 55 tical supporting legs of the guide may be swivelly mounted on the furnace assembly as by means of the screw stud I40 and the other leg is detachably fastened by a similar stud so that the frame can be swung about a vertical axis and to one side.'

0 I claim: 1. Operating mechanism for a die casting machine, including a pair of fluid pressure actuated operating units operable, respectively, to close the die and to inject molten metal into the closed die,

5 a source of pressure fluid adapted for communication with the unit which operates to inject metal into the die, a second source of pressure fluid adapted for communicationjwith the die 7 closing unit; and means active after a predeter- 7 mined response of the last mentioned unit from fluid pressure supplied by said second source to communicate the first mentioned source of pressure with said last mentioned unit.

2. In a die casting machine, a pair of relatively 7 movable diemembers, a fluid pressure operated When the melting pot is device associated with said members for eflecting their relative movement, means to supply pressure fluid to said device including a pair of pumps. means to-connect one of said pumps with said device throughout the range of movement and means active in a predetermined intermediate I fluid pressure to operate the last mentioned device, a second source of pressure fluid independent of said first mentioned source to operate the first 15 mentioned device and means active within a predetermined intermediate portion of the stroke of the first mentioned device to superimpose pressure fluid from the flrst source on that supplied by the second source for accelerating the opera- 20 tion of said device.

4. In a die casting machine, a die operating piston, a cylinder containing said piston, a pair of conduits leading to opposite ends of the cylinder,

a two-way valve adapted to communicate either of said conduits with a source of low pressure fluid and concurrently vent the other conduit, a check valve in one of said conduits adapted to be opened by fluid flow through the conduit to the cylinder, a high pressure line leading to the end of the cylinder beyond said check valve so that fluid flow therethrough closes said check valve, a fluid pressure actuated valve operating device to open ,said check valve and means to supply pressure fluid to said device when said two-way valve vents the conduit containing the check valve and communicates the other conduit with said source of pressure fluid. 1

5. In a die casting machine, a die operating device movable in opposite directionswithin a chamber in response to pressure differential on opposite sides thereof, a pair of conduits communicating with the chamber on opposite sides of said device, a two-way valve to connect either conduit with a source of fluid pressure and concurrently drain the other conduit, a check valve in one of said conduits, a fluid pressure actuated booster connected beyond said check valve, means to supply actuating fluid pressure to the booster,

a check valve associated with said means, pressure actuated devices associated with both check valves to open the same, and means active through said two-way valve when the conduit containing the check valve is being drained to supply actuating fluid to both of said pressure actuated devices.

6. In a die casting machine, a frame, a reciprocatory carriage on the frame for opening and closing a die, a pressure fluid actuated device mounted on the carriage for performing a service co operation, a valve mounted on the frame for supplyingfluid pressure to said device, a pawl slidable on the carriage to engage a valve operating member to set the same in either of two positions, one of which completes a circuit for the pressure 35 'fluid, and the other of which supplies fluid pressure to oneside of said device, means for'tripping the pawl to set the valve in a third position for supplying fluid pressure to the other side of the device and means connected with the pawl and 7 movable with the pressure responsive device after tripping the pawl to slide the pawl to a setting for engagement, upon the return strokeof the carriage, with theva-lve operating member and thereby move the valveto the second mentioned 7 position, and upon response of said device to such valve setting to slide the valve in the opposite direction and thereby set said valve in the first mentioned position.

7. In a die casting machine,control mechanism for a fluid pressure device which moves the die between opened and closed positions, including, a two-way valve to supply fluid pressure to said device, means biasing the valve toward die opening position, means for shifting the valve manually to die closing position, latch means to hold the valve in its manually set position, an electrically actuated device to release the latch, timing mechanism controlling the actuation of said latch releasing device, and a switch to set the timing mechanism into action automatically when the die is closed.

8. In a die casting machine, a reciprocable die actuating device movable in response to pressure diiferential on opposite sides thereof, a two-way valve adapted when in one position to supply fluid pressure on one side of the device to close the die and when in the other position to supply pressure fluid to the other side of the device to open the die, means responsive to pressure differential on opposite sides thereof to depress and retract a' metal feeding plunger, a two-way valve to supply operating fluid pressure on either side of said means, manual meansto set the first valve in die closing position, a releasable latch to retain the valve in its manually set position, means de-' pendent upon die closing position of the first device automatically to set the second valve in plunger depressing position, timing mechanism to render said setting means inefiective so as, to set the valve in plunger retracting position, addi-' vice, a fluid pressure actuated valve operable to connect said pressure fluid source with both the last mentioned device and the booster, secondary valve means operable to connect said pressure fluid source with both the booster and said pressure actuated valve and means acting automatically when the die is closed to operate the secondary valve means.

10. Control mechanism for a die casting machine, having a movable die carriage and a fluid pressure actuated ejector mechanism mounted on said carriage, a valve operating plunger adapted when in one position to communicate said ejector mechanism with a source of operating fluid and when in another position to by-pass said mechanism, a projectible abutment on said carriage adapted to engage said plunger coincident with carriage movement to move the same to the first mentioned position and means operating in response to said ejector mechanism to project said abutment for moving the plunger to the second mentioned position.

11. Control mechanism for the sequential operation of the fluid pressure actuated devices of a die casting machine, including a fluid pressure actuated valve' adapted upon pressure fluid application thereon to supply operating pressure fluid to metal injecting means and to a booster associated with die closing means, a control valve adapted when open toflow operating pressure fluid to the booster and the first mentioned valve,

amaster valve adapted when manually set ;to supply operating pressure fluid to the die closing means and through said control valveto thefirst] sure fluid to metal injecting means and to a pressure fluid booster associated with die closing means, a-valve controllingpressure fluid flow to the fluid pressure actuated valve for its actuation and to the booster in advance of the supply from the pressure actuated valve, means operated automatically to open said control valve when the die is closed, and a manually set valve adapted to supply pressure fluid to a die closing means and through said control valve to the pressure actuated valve and the booster.

13. In a die casting machine, a source'of fluid pressure, die closing means and metal injecting means, both operated by pressure fluid from said source, a fluid pressure actuated booster associated with the die closing means to increase fluid pressure thereon, a fluid pressure actuated valve adapted to communicate the pressure fluid source simultaneously with both the metal injecting means and the booster upon the application thereon of pressure fluid, a manually set valve adapted when in manually set position to communicate the pressure fluid source simultaneously with the die closing means and said fluid pressure actuated valve, an electrically actuated valve interposed between said valves and adapted when actuated to pass pressure fluid simultaneously to the fluid pressure actuated valve and to the booster and means actuated by the die closing means when in die closing position to supply current to said electrically actuated valve.

14. In a die casting machine, a movable die carriage, a fluid motor therefor, a pair of pumps for supplying pressure fluid to said motor, a valve controlling fluid flow from one of the pumps,

and a valve operating cam bar supported by the carriage and having valve closing camrning abutments spaced apart .and active on the valve near O posite limits of carriage travel.

15. Control mechanismfor a die casting machine including a valve casing mounted on a stationary part of the machine, a valve operating plunger movable to any one of three positions to control flow of pressure fluid in bne position to project an ejector mechanism carried by a mov able die carriage, in another position to retract .said mechanism and in the third position'to bypass said mechanism, a projectible abutment on the carriage to engage said plunger and move the same coincident to carriage movement to its ejector projecting position, means movable with the ejector mechanism to project said abutment for moving the plunger to its by-passing position and a manually operated trip device to disengage the abutment and plunger for plunger movement to ejector retracting position.

' MARC STERN.

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