US2618292A - Valve for die casting machines - Google Patents

Description

Nov. 18, 1952 L. RING 2,618,292

VALVE FOR DIE CASTING MACHINES Filed April 3, 1950 Patented Nov. 18, 1952 VALVE FOR DIE CASTING MACHINESv Lucian Ring.v Detroit, Mich., assignor tn Ringg Valve Company, Clawsoin of Michigan Michl., a corporation)` Application AprilA 3, 1950, Serial No.153,(52 l 3 Claims.` (C1. 13T-m5)V Thisnvention relates to die casting machines oill the type wherein the material to be cast is.

forcibly injected into the diek cavity.

It'isan object of this invention Hto provide a valve'whichrenders adie casting machine automatic in operation, and which causes vthe macliiieto produce uniform substantially nonpo'rous .castings 'having' unusually smooth sur? face. finishes,v withno special attention or Inanipulation required on the part of the operator. Thuslrelatively unskilled. operators may be employedwithout affecting the quality of the castings, and uniformity of the castings is assured'.

In accordance ,with this invention, substantially nonporous-c'astings having superior surface nisles vareobtairled by forcibly injecting thematerial i'ntothe diecavity in two stages. In the first Stage. the materalis gradually fed into the diecavity at a ratesuch that any air or gas presenti'n the cavity has a chance to escape through theA vent provided in the cavity for this purpose before. the` material solidies. In the second or iinaljstage, the rate of feed of the material is greatly'accelerated; so that the material, in effect, is shot into thecavity and lls all portions offthecavity before solidiflcation takes place.

It is another object of this invention to provide a2..valve for a die casting machine of the above typewherein the two stages of injection are automatically effected in the operating cycle of the machine, and wherein the feeding rates as well as the timing between the two stages may be readily varied to'suit different conditions.

The foregoing as well as other objects will be made more apparent as this description proceeds, especiallywhen considered in connection with the accompanying drawing, wherein:

Figure 1 isasemidiagrammatic view partly in section of. adie casting machine embodying the features of this invention; and y Figure 2 is a longitudinal sectional view 'through ak part of thefmachine shown in Figure l.

ItI will be understood as this description proceeds that the present invention may be successfully used in connection with numerous different types of die casting machines. However, for the purpose of illustration, I have shown in Figure 1 a die casting machine having a base I and a die II. The die II has two parts I2 and I3 whichv cooperate with one another to form a cavity I4.

The die part I2 is xed on a plate I5 which extends generally vertically from the base I0, andthe cooperating part I3 is suitably supported on aplate IB. The plate I 6 is mounted on guides I'I which inturn, are supported on the base II] in amanner to provide for sliding movement of th edie part I3 toward and away from the die partdl 2. In the present instance a suitable power drivencrankrl isalso supported on the base I ang-is ,confleiedioihe Plaie, I6 by@ rod, `lq

for moving the die partv I3 into and putofenf gagement with the cooperatingdiepartlt. The material .or'metal to be cast intor thedie cavity I4, is normally stored "in a meltingpot 20,; which projects into a furnace or heating chang.l ber'2I'. The furnace 2i is also supportedon the..

base IDQ and incorporates heating elements of" any suitable typefor maintaining thematerialinf the pot 20 inamoltenstate.V i

It.v will further be noted from Figure 1 ofthe drawing that a die charging pump 22 is suitably'Y mounted withinv the pot` 2i).v This p'urfnpy coin; prises a vertically extendingfcylinder 23` and a plunger 24 supported in thecylinderforslidingi movement relative thereof.` 'Ihecylinder 23jis]v closed at the bottom, andpis fashiond with a goose-neck nozzle portion 25.k The nozzle Vpor.-S tion 25 extends upwardly through the topfof thel pot 20,y and projects through 'thedie supporting` plate I5 into engagement with the stationary.die` part II2 atv aV point spaced laterallyabovev they cavity I4. A'dis'chargefpassage 2t'is.formedfin the goose-neck portion 25 and connects'the'lowe'r, y

end of the cylinder 23 to the cavitythroughrthg medium of a sprue opening2I in the die. It will be understood that the exposed portions ofy the,

into the cylinder 23 below the yplunger 2F. when.

the latter is in its raised position. The arrange.- ment` is such that downward lmovement of vthe plunger 24 from its raised position in thecylinder 23 forces molten metalthrough the passage zii and sprue opening 2'I into the die cavity I4. On

the other hand, return movement of the plungerY 24 to its raised position uncovers the inlet portv 28 and permits another charge of moltenrmetalv to flow into the cylinder 23 below the plunger.v

The plunger 24 is reciprocatedin the cylinder.v

23 Eby a hydraulic cylinder assembly or motor. 29 suitably supported above the melting pot. 20. The assembly 29 comprisesia vertically. extending cylinder 3f] and a piston 3| slidably supported inthecylinder. The plunger 24 is connected to the piston by a vertical rod 3| which extends'upv wardly through the bottom of the cylinder 36.

The upper end of the cylinder communicatesu with a conduit 32, and the llower end of the: cylinder communicates with a conduit 33. In operation these conduits are, alternately connected to a source of hydraulic fluid under pressure 34 and a reservoir 35 through the mediumof a four-way valve 36. In accordance withl conventional practice the valves 35v has; a portI 3'I1 which kis connected k.to ,the .source/of .fluidunder1 pressure 34 and has a port 38 which is connected to the reservoir 35. Also the Valve 36 has a pair of ports 39 and 46 which are respectively connected to the conduits 32 and 33. The valve 36 may be any one of a number of designs available to the trade, and is therefore not shown in detail herein. It will suffice to point out that during operation of the casting machine the valve 36 is operated automatically to alternately connect opposite ends of the cylinder 36 to the source of fluid under pressure 34 and to the reservoir 35.

Also in accordance with the present invention, downward movement of the plunger 24 to inject molten metal into the die cavity I4 isautomatically'controlled, so that initial downward movement of the plunger 24 is effected at a relatively slow rate, and iinal movement of the plunger in a downward direction is effectedat a rapid rate. In practiceV the rate of initial movement of the plunger 24 is determined to provide ample time for air or gasV entrapped in the die cavity I4 to escape through the vent 4lY in the die, and the iinal stroke of the plunger 24 is accomplished at such a rapid rate that the metal is actually shot into the die cavity. Thus complete lling of all portions of the die' cavity is assured after all gases or air are evacuated from theV die cavity, and accordingly, a dense relatively nonporous casing results.Y

The downward stroke of the plunger 24, or in other words, the flow of molten metal into the die cavity I4 is controlled by interposing between the four-way valve 36 and the top of the cylinder 30, a valve 42 of the type shown in Figure 2 of the drawing. The valve 42 has a cylinder 43 closed at both ends by caps 44 and 45 which cooperate with the cylinder to form a chamber 46. The cylinder 43 has a pressure inlet port 41 intermediate the ends of the chamber 45 and communicating with the port 36 of thefour-way valve, in order to receive fluid under pressure from the source 34 before this fluid is admitted to the upper end of the cylinder 30. The cylinder 43 is also formed with a pressure outlet port 48 communicating with the chamber 46 at a point between the port 41 and the cap 45. The port 43 is also connected to the upper end of the -cylinder 35 through the medium of the conduit 32.

The flow of uid under pressure from the inlet port 41 to the outlet port 4B, or in other words, to the upper end of the cylinder 36 is controlled by a Valve member or spool 45 ofthe balanced pressure type and supported for sliding 'movement in the chamber 46. The valve spool has a head 50 at one end and a head 52 at the opposite end connected to the head 56 by a reduced part 53. The head 56 slides in the chamber 46 between the cap 44 and pressure inlet openingr 41. The valve head 52 on the other hand slides in the chamber 46 `between the cap 45 and pressure inlet port 41, and controls the outlet port 48. In this connection it will be noted that when the valve spool 49 is in the position thereof shown in Figure 2 wherein the head 56 abuts the cap 44, the outlet port 48 is closed by the head 52. Movement of the valve spool forwardly from the above position or in a direction toward the cap 45 positions the valve head 52 between the cap 45 and outlet port 48 in -a position to connect the outlet port 48 to the inlet port 41.

The valve member 49 is normally held in the position thereof shown in Figure 2 of the drawing by the presence of hydraulic or nonccmpressible fluid medium within the space in the chamber 46 between the valve head 52 and cap 45. In this connection, it will be noted that lthe cap 45 has a passage 54 therein connected at one end to the port 46 in the four-way valve 36 or to the conduit 33 leading from the bottom of the cylinder 30 and connected at the other end to the chamber 46. Thus when the lower end of the cylinder 36 is connected through the four-way valve 36 to the source of fluid under pressure 34, the space between the cap 45 and adjacent head 52 on the valve spool 46 is lled with the fluid medium, and since the latter is noncompressibla it follows that the valve spool 49 is maintained in the position thereof shown in Figure 2.

It will further be noted from Figure 2 of the drawing that the valve cylinder 43 is formed with a passage 55 which connects the pressure outlet port 48 to the chamber 46 opposite the inlet port 41, or in other words, at a point between the valve heads 56 and 52. Thus the passage 55 bypasses the head 52 on the valve spool 49, and enables the flow of uid under pressure from the portv 41 to the outlet port 48 when the valve spool 49 is in the position shown in Figure 2 ofA the drawing. The rate at which the uid under pressure is bypassed is regulated by a needle valve 56 positioned to vary the eiective cross sectional area of the passage 55 from zero to a predetermined maximum. In other words the needle valve 56 renders it possible to vary the rate of initial downward movement of the plunger 24 to chargeV the die cavity I4 with molten metal.

Referring again to Figure 2 of the drawing, it will be noted that the pressure inlet port 41 is connected by a passage 51 to the space in the chamber 46 between the valve head 5D and the cap 44. The purpose of the passage 51 is to enable movement of the valve spool 49 in a direction to displace fluid from the chamber 46 inV advance of the head 52 through the passage 54. It will be understood that the rate of displacement in advance of the valve head 52 controls the time ci" opening of the pressure outlet port 48, Yand this timing may be varied by metering valve 59 positioned to regulate the rate of uid flow through the passage 54.

Operation It will be understood from the foregoing that when the four-way valve 36 is operated to connect the lower end of the cylinder 30 to the source 34 of fluid under pressure and to connect the upper end of the cylinder 36 lto the reservoir, the plunger 24 is in its uppermost position wherein molten material from the pot 20 is free to ilow through the inlet portY 28 into the cylinder 23 below the plunger 24. Also when the four-way valve 36 is in the above position, the valve spool 49 assumes the position thereof shown in Figure 2 of the drawings, and the space in the valve chamber 46 in advance of the valve head 52 is filled with hydraulic or noncompressible fluid medium.

Assuming now that it is desired toY charge theV mold cavity I4, the four-way valve 36 is moved to connect the lower end of the cylinder 30 andpassage 54 in the valve 42 to the reservoir 35, and to connect the pressure inlet port 41 of the valve 42 to the source 34 of fluid under pressure. As a result liuid under pressure ows through the port- 41 into the space in the valve chamber 46 between the valve heads 56 and 52, whichfspace also communicates with the by-pass passage 55. As a result fluid under pressure is bypassed to the outlet port 48 or upper end of the cylinderf30' at a# rate determined by the metering valve 56. Con-V sequently, pressure is gradually built up in the cylinder 3U above the piston 3l; and the latter, together with the plunger 24, is moved downwardly at a relatively slow rate.

As the plunger '24 moves downwardly the port 28 is closed and molten metal in the cylinder 23 below the plunger is forced through the passage 26 into the die cavity I4. The relatively slow rate of feed of the molten material into `the die cavity I4 affords ample time for any air or gas in the cavity I4 to escape through the vent 4I in the die.

Also during the above operation uid under pressure ows from the pressure inlet port 41 through the passage 51 into the valve chamber 46 between the cap 44 and the valve head 59. The force resulting from the pressure acting on the head 50, moves the valve spool 49 in a direction toward the cap 45. Since the space in the valve chamber 46 in advance of the valve head 52 is connected to the reservoir through the passage 54, it follows that the valve spool moves forwardly at a rate depending upon the setting of the metering valve 59 or upon the rate of escape of fluid through the passage 54 to the resorvoir 35. Eventually sufficient fluid in advance of the head 52 is displaced to connect the pressure outlet port 48 directly to the pressure inlet port 41. When this takes place fluid under pressure flows in a relatively unrestricted manner to the upper end of the plunger operating cylinder 30 and.

downward movement of the plunger is greatly accelerated. Accordingly the rate of flow of molten metal into the die cavity I3 is correspondingly accelerated, and the cavity is suddenly completely filled with the molten metal. movement of the plunger 24 is, of course, delayed until all air or gas has been expelled from the die cavity I4, and the interval in the cycle at which acceleration of the plunger is effected may be varied by the metering valve 59.

After the die cavity I4 is completely charged the four-way valve 36 is manipulated to again connect the upper end of the cylinder 30 or the pressure inlet port 4'I to the reservoir 35, and to connect the lower end of the cylinder 30 as well as the passage 54 to the source 34 of fluid under pressure. Thus the plunger 24 is not only returned to its uppermost position in the cylinder 23, but the valve spool 49 is also returned to the position shown in Figure 2 of the drawing, wherein the pressure outlet port 48 is closed by the valve head 52, and the space between the head 52 and cap 54 is filled with hydraulic fluid medium.

What I claim as my invention is:

1. Means for controlling the ow of iiuid between a source of fluid under pressure and a, fluid motor, comprising a valve having a cylinder and a piston supported in the cylinder for sliding The accelerated I movement between positions adjacent opposite ends of the cylinder, said cylinder having a first port opening into-the space between one end of the cylinder and the adjacent end of the piston, said first port being adapted to supply fluid under pressure to said space to move the piston toward the other end of the cylinder and being adapted to conduct fluid away from said space upon movement of the piston toward said one end of the cylinder, said cylinder having a, second port opening into the space between the said other end of the cylinder and the adjacent end of the piston, said second port being adapted to supply uid under pressure to the second mentioned space to move the piston toward said one end of the cylinder and being adapted to conduct fluid away from the second mentioned space upon movement of the piston toward said other end of the cylinder, said second port having valve means therein for reducing the effective size thereof and restricting the flow of fluid therethrough to retard the movement of the piston toward said other end of the cylinder, said cylinder having an outlet port positioned to be closed by the piston in its position adjacent said one end of the cylinder and to be opened by the piston upon movement of the latter toward said other -end of the cylinder, sai-d cylinder having an outlet passage in communication with the first port when the outlet port is closed by said piston, and said outlet passage being relatively restricted as cornpared to the outlet port to restrict the flow of uid therethrough to a rate less than that permitted through said outlet port.

2. Means for controlling the flow of uid between a source of fluid under pressure and a uid motor, comprising a valve having a cylinder and an inlet port opening into said cylinder, a piston supported in the cylinder for sliding movement between positions adjacent opposite ends of the cylinder and having spaced heads positioned at opposite sides of the inlet port, said cylinder having a second port opening into the space between one end of the cylinder` and the adjacent piston head, said second port being adapted to supply uid under pressure to said space to move the piston toward the other end of the cylinder and being adapted to conduct uid away from said space upon movement of the piston toward said one end of the cylinder, said cylinder having a third port opening into the space between the said other end of the cylinder and the adjacent piston head, said third port being adapted to supply fluid under pressure to the second mentioned space to move the piston toward said one end of the cylinder and being adapted to conduct uid away from the second mentioned space upon movement of the piston toward said other end of the cylinder, said third port having valve means therein for reducing the effective size thereof and restricting the ilow of fluid therethrough to retard the movement of the piston toward said` other end of the cylinder, said cylinder having an outlet port positioned to be closed by one of the piston heads in the position of said piston adjacent said one end of the cylinder and to be opened upon movement of the piston toward said other end of the cylinder, said cylinder having an outlet passage opening into the space between the piston heads, and said outlet passage being relatively restricted as compared to the outlet port to restrict the flow of fluid therethrough to a rate less than that permitted through said outlet port.

3. The construction defined in claim 2 wherein the valve means in said third port is adjustable to vary the effective size of the latter and consequently the flow of fiuid therethrough, thereby to vary the rate of travel of the piston and hence the time required to open the outlet port.

LUCIAN RING.

REFERENCES CITED The following references are of record in the file of this lpatent:

UNITED STATES VPATENTS Number Name Date 2,173,377 Schultz et al. Sept. 19. 1939 2,182,059 Schwartz Dec. 5, 1939 2,494,071 Veale Jan. 10, 1950 2,532,256 Holmes et al Nov. 28, 1950

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