US2864140A

US2864140A - Vacuum die casting means

Info

Publication number: US2864140A
Application number: US543832A
Authority: US
Inventors: David M Morgenstern
Original assignee: Package Machinery Co
Current assignee: Package Machinery Co
Priority date: 1955-10-31
Filing date: 1955-10-31
Publication date: 1958-12-16
Anticipated expiration: 1975-12-16

Description

M, W5@ D. M. MORGENSTERN 64,146

VACUUM DE CASTING MEANS Filed Oct. 3l, 1955 2 Sheets-Sheet 2 IN VEN TOR.

@A wo MMmfNre-RN rro/QNE y 2,864,140 VACUUM DIE CASTING MEANS David M. Morgenstern,

and rnesne assignments, to pany, East Longmeadow, Mass., Massachusetts Euclid, Uhio, assigner, by direct Package Machinery Coma corporation of This invention relates to the art of die casting under vacuum, the Virtues of which, from the standpoint of product, have long been recognized. It is well known, however, that the principal objection to the production of die casting under vacuum by means and methods representative of the prior art, has been that production is slow and, therefore, expensive. Considerable advancement in the art was made by the method and apparatus disclosed and claimed in the copending application of Alfred P. Federman and the present applicant, tiled January 12, 1954, Serial No. 405,565J now Patent No. 2,799,066, dated July 16, 1957.

As in the case just referred to, the invention is applicable to die casting machines generally of the kind now in use.

An object of my present invention is to maintain substantially the same speed of production in the manufacture, by the 'vacuum method, of high quality, smooth surface and dense castings, as was heretofore attained in the production of inferior castings without the benefit of evacuation of the die cavity. l may mention here that a very considerable ysaving is effected by the use of my improvements because of the resultant great reduction in the percentage of rejects encountered in a run of castings, this being but one of the many advantages.

Another object of my invention is to provide equipment that lends itself to the handling of all kinds of materials suitable for die casting, including plastics and a variety of metals, such as zinc, aluminum, and alloys thereof, and which7 at the same time, is peculiarly sui-ted to the handling of magneslum and other materials that are unstable and highly susceptible to oxidation while in molten condition when exposed to the atmosphere. This suitability of the equipment to the handling of the latter materials arises from the fact that l employ a Crucible, and a charging system for conveying molten material therefrom, first, to a charging chamber, and thence to the die cavity, that are so constructed as to be capable of being substantially closed throughout to the atmosphere, thereby to practically obviate oxidation.

Another more specific and related object is to provide, in the die casting equipment, a unique charging system which in part, is similar in structure and function to the so-called cold chamber arrangement and technique, but which eliminates the hand ladling of the molten material into the charging chamber during each cycle of operation of the die casting machine.

-An important feature of the present apparatus, as well as of the apparatus disclosed in the aforesaid application7 is a two-part enclosure or hood that encompasses the die members, one of the parts being secured and sealed to the stationary die plate, and the other to the movable die plate, the parts meeting in the general region o-f the line of separation between the die members, it being desirable that the open side of the part secured to and shiftable with the movable die plate be somewhat to the rear of the front face of the movable die member.

As well known to those familiar with the art of die atene 'ice casting, die members of different sizes, and die members having die cavities of varying depth, are adapted to be used in the same die casting machine, and it is another object of the invention to construct the enclosure or hood so as to allow convenient access to the die members for changing them or for other purposes. Another object is to provide a displacement element that may be disposed inside the enclosure or hood and occupy some of the otherwise vacant space so as to reduce the effective cubic capacity of the enclosure or hood and thus expedite evacuation thereof and contribute to the speedy operation of the apparatus.

The hood or enclosure is desirably provided with one or more Vhand holes that are adapted to ber-sealed by closure means, and itis a further object to combine the displacement element with such closure means.

A still further object of the invention is to make one of the hood parts, desirably the part that is carried by the stationary die plate, extensible, as by incorporating in the peripheral wall thereof a flexible section in the nature of a bellows, said part of the hood being biased toward projected position so that the hood will close and become sealed considerably in advance of the meeting of the die members, thus affording ample time to create a vacuum of the required degree in the hood and cornmunicating spaces before the die cavity is closed.

Another and related object is to provide adjustment means whereby the distance of projection of said hood part is capable of being varied according to the depth of the die cavity and the parts, if any, that project thereinto.

With reference to the feeding of the molten material to the charging chamber, it is another object of the invention to provide a part or plug having a metering oriiice, that is conveniently interchangeable with parts or plugs having metering orifices of different sizes, and that serve to control and measure the flow of molten material into the charging chamber and limit the quantity of material delivered to the chamber within the feeding phase of a cycle to slightly more than that required to lill the die cavity.

Another object is to locate spaced electrical contacts adjacent the bottom of the hood that will be bridged by any molten metal that may accidentally overflow into the hood, or that will be bridged by other foreign matter having electrical conductive properties whose presence may adversely affect the operation of the apparatus, which contacts are in an electric circuit that operates in conjunction with suitable electrical means to shut down the operation of certain parts of the apparatus, thus making it necessary to remove the metal or other matter before `operations can proceed.

The objects and advantages above enumerated, with others hereinafter appearing, are attained in an embodiment of the invention that is more or less schematically illustrated in the accompanying drawings; and it will be understood that said embodiment is to be taken as illustrative rather than as limiting, and that such changes and modifications may be made therein as fall within the scope of the claims appended hereto.

In the drawings:

Fig l represents a fragmentary sectional side elevation of a die casting machine incorporating my improved charging system and equipped with the vacuum apparatus of my invention, the die members being in engagement and the hood closed and evacuated, as evidenced by the condition of the valves associated therewith, a charge of molten material being shown in the charging chamber ready to be projected into the die cavity by the operation of the ram; and

Fig. 2 is a sectional view, similar to Fig. 1 but of less scope, showing the die members separated, the hood open,

vtuator or rod 15, that is arranged to engage 2,se4,14o

and the adjacent parts of the apparatus in the condition they assume between cycles. l

The die casting machine wherewith I have shown my improvements associated is of a conventional design and construction, excepting for the unique charging system of my invention, and for the sake of simplicity and clarity only the essential parts of the machine are shown.i The machine includes the usual stationary die plate l-.and movable die plate rods (not shown) a machine.

Suitably secured to the respective die plates 1 and 2 are a stationary die member 5 and a movable die member 6, by and between when the die members are together. Within a relatively large recess 8, shown as formed in the end of the die member 6 adjacent the plate 2, operates ejecting mechanism comprising a headA 10 and ejecting pins 11 that are carried by said head and extend through bores in the movable die member 6, and when the dies are in condition to receive a charge of molten material, the forward ends of said pins are substantially iiush with the surrounding surface of the die member 6 that is exposed to the die cavity 7. The retraction of the ejecting pins to bring about this condition is etected by one or more push rods, one such rod being shown and designated 12. One end of said rod is engaged Vwith or is fastened to the head 10 and the opposite end portion thereof is guided through aubore of the movable die member 6. As the movable die member closely approaches the stationary die member 5, the forward end of the push rod engages the latter die member thereby to arrest forward movement of the head 10 and consequently of the ejecting pins 11, while the die member 6 completes its forward travel, all in accordance with common practice.

Secured to and projecting rearwardly from the head 10, through a bore in the movable die plate 2, is an aca stationary abutment 16, that is usual in die casting machines of the kind disclosed, when the die plate 2 is retracted. A flexithat are well known elementsof" such Vble diaphragm or bellows 18 has one of its ends secured and sealed to the actuator and its opposite end attached with a leak-proof joint to the movable die plate, thereby to prevent passage of air through the bore through which the actuator operates.

Toggle joints 20 are pivotally connected at their forward ends to the movable die plate 2 and at their opposite ends to a stationary part 21 of the machine, and said toggle joints are connected by links 22 to a head 23 that is carried by the forward end of a piston rod 24. The Vrod 24 extends through an opening in the stationary part 21 and has secured Vto its end remote from the head 23 a piston 25 that reciprocates within a cylinder 26. The piston 2S and cylinder V26 constitute a power unit for operatingV the movable die plate and shifting the parts carried thereby toward and from the parts attached to the stationarykdie plate 1. Y,

I mayhere make mention of a switch actuator 28 ,that is shown as connected, by a rod 29, to the piston 25. In the path*V of this actuator are a die open limit 'switch 30 that is biased to closed position, a so-called evacuating switch 31, and a die close limit switch 32, which, like switch 31, is biased to open position. The purpose of these switches will presently appear.

Operatively associated with the power unit comprising the piston 25 and cylinder 26 are a master'die closing valve and a master die opening valve 36, andv the operation of these master valves is effected through the respective pilot valves 35a and 36a.

Turning now to the charging system: 38 is a housing or shell that encloses a charging chamber40 that is desirably cylindrical. The forward end `of said housing or shell 38 projects'through and is sealed in aligned openings of the stationary die plate 1 and the attached die member 5. The chamber 40 communicates with the die cavityY 7 through a channel 41, the end of which'adjacent which a die cavity 7 is defined` 2, the latter being slidable along strain i said chamber is formed in an insert 42 composed of a substance resistant to the eiects of the molten material. The body portion of the insert 42 occupies a recess in the movable die member 6, while the forward end of said insert projects beyond the face of said die member and seats within a recess in the face of the stationary die member 5, abutting the adjacent end of the housing or shell 38 of the charging chamber 40, when the die members are together and the die cavity is closed.

Clamped-about the protruding end of the shell or housing 38 is a' two-part -block 44. The bottom portion of `the block has a vertical bore that is threaded adjacent its lower end for the reception of a screw plug 45 which supports a duct member 46 ofa material suitable to stand the heat and corrosive etect of the molten material and, thereabove, a metering means or plug 47 that is characterized 4by a llow control orice. The metering means or plug 47 may consist of a relatively thick washer-like body of a substance that will be unatfected by the molten material, the orifice being of such capacity as will permit entrance into the charging chamber within a given time, through a port 48, of sucient metal to lill'the die cavity and channel `41 and the adjacent end of the charging chamber. The lower part of the block 44 has a bore bisecting the one occupied by the duct member 46t and the metering means 47, and into one end of said bore isf engaged the upper, laterally turned end of a conduit 49'. This conduit leads upwardly from a crucible 50 that is' heated `by suitable means (not shown) said conduit extending to near the bottom of the crucible and below the minimum level of molten metal therein. The portion of the-conduit inside the crucible is shownAas surrounded by a sleeve 51 of refractory material and, if desired, the portionl of the conduit above the crucible may be wrapped with suitable heat insulating material. The end of the bore of the block 44 opposite the one into which the conduit 49 extends is closed by a screw plug 53. The housing or shell 38 of the charging chamber is provided with a. hole 54 that is diametrically opposite the port 48 and is aligned with a vertical bore in the top part of the block 44, said bore being threaded at its upper end for the reception of a screw plug 55. Removal of the plugs 53 and 55 gives access to the parts that occupy the ver tical -bore in the lower part of the block so that by the use of a suitable instrument, the parts may be displaced, as when changing the metering means or plug 47 for one having a flow orifice of different size or capacity.

AIn order to especially adapt the apparatus to the handling of magnesium and other metals that are unstable .and subject to oxidation when, in molten condition, they are exposed to the atmosphere, and while in no way afecting the handling 'of other materials,l metals and metal alloys, the crucible has suitably sealed to itsupper end a cover 58 that is provided with an opening through which material may be placed in the crucible and which is normally sealed by a closure 59.

A tank orrbottle '60, adapted to contain an inert gas under pressure, is placed in communication with the crucible through a pipe 61 that includes a gas valve 62. The valve member 63 carries -a piston 64 that operates within a cylindrical chamber in the valve casing, and a spring 65 tends tourge the piston in a direction to open the valve. The piston 64 is adapted to be projected, so as to close the valve, by pressure Huid admitted to said chamber through a pipe 66 that leads from a pilot valve 67 of the spool type, a spring 68 tending to shift the valve to a position wherein an inlet pipe 69 for the pressure tluid'is Vin communication with the pipe 66. -The valve is shifted to its other position against the action of the spring 68 by a so-called gas solenoid 70. Thered fore, when the solenoid 70 is energized it will establish communication between the pipe 66 and an outlet pipe 71, thereby t-o allow the spring 65 to retract the valve and open communication through the pipe 61 between the gas tank or bottle 60 and the crucibl A 4ram 75 operates within the charging chamber 40 and has connection, through a rod 76, with a piston 77 that is reciprocable in a cylinder 78, said piston and cylinder constituting a power unit by which the ram 75 is advanced and retracted. It will be observed that when the piston 77 is at the right hand end of the cylinder 7S, as the `parts are viewed in the drawings, the ram 75 uncovers the port 48, and due to the length of travel of the piston, the ram 75 may be advanced to within a short distance of the discharge end of the charging chamber. As will more fully appear hereinafter, the operation of the power unit comprising the piston 77 and cylinder 78 is under the control of a so-called shot valve 80 while said valve, in turn, is under the control `of a pilot valve 80a, the spool type valve member of which is urged in one direction by a spring 81, and is moved in the opposite direction by a solenoid 82.

85 denotes, generally, a two-part hood or enclosure, the sections or parts whereof `are designated 86 and 87. The part S6 is carried by and sealed to the stationary die plate 1 and surrounds the die member 5 that is attached to said plate, while the part 87 is fastened to the movable die plate 2 and surrounds the movable die member 6, the `parts of the enclosure or hood meeting in the region of the vertical plane of separation between the die members. The part 87 is effectively sealed to the movable die plate, against the ingress of air, -by a sealing strip 90 `of llexible material, such as a suitable plastic, that is secured to the adjacent end of the hood part 87 and overlies the peripheral surface of the die plate 2. This type of seal is very elfective inasmuch as the pressure of the strip 90 upon the underlying surface ofthe plate increases as the degree of vacuum within the hood increases.

The open side of the hood part 87 is surrounded by a flange 93 having a smooth front surface. Arranged for contact therewith is a flexible gasket 94 that is secured adjacent its inner edge to the contiguous end of the hood part 86, whichpart includes a rigid wall section 95. When the hood is open, so to speak, as when the movable die plate is in retracted position, as the parts are shown in Fig. 2, the gasket 94 assumes a steep angular relation to the plane of the open side of the hood part 86.

A second rigid wall section 96 has one of its ends secured and sealed to the edge portion of the stationary die plate 1, and attached with a leak-proof joint to the opposite end of the wall section 96 is the adjacent end of a ,bellows-like flexible wall section 97 whose opposite end is attached and sealed to the stationary wall section 95. This renders the part S6 of the hood extensible, and said part is biased toward projected or extended condition by a suitable number of spring means that are spaced at intervals about the hood part 86, and one of which is shown in Figs. l and 2. Said means consists of a spring 100 that surrounds a bolt or the like 101 that is supported at one end against endwise movement by a bracket 102 that is fastened to the stationary wall section 86, and is slidable at its opposite end through an aperture in a bracket 103 that is carried by the rigid wall section 95, an abutment member or nut 105 being threaded or otherwise adjustably connected to the end of the bolt or the like 101 beyond the bracket 103. Suitably supported, as by the stationary wall section 96, in intimate heat exchange relation to the lexible wall section, is a conduit 106 through which water or other suitable coolant is adapted to be circulated. While the flexible wall section 97 is, according to the present embodiment, made of a ilexible plastic that will withstand a high degree of heat, the life of the material may somewhat be prolonged by maintaining it relatively cool by the means described.

Shown as located adjacent the bottom of the hood, and as secured and sealed to the part 86 thereof in register with an opening 108, is a duct member 110. Since this .duct member is, in the present instance, located at the bottom of the hood, it is suitable for the support of spaced contact points 111 and 112, which are insulated from each other and from the surrounding portion of the conduit member. These contact points are included in a safety circuit, as will hereinafter more fully appear, and they are adapted to be bridged by an accumulation of metal that may accidentally overllow from the charging chamber and be deected by a baille 114 through the opening 108. Also, any foreign matter of a conductive nature will bridge the contacts 111 and 112 if such matter collects thereabout in sufficient quantity to adversely affect the operation of the apparatus. The safety circuit referred to further includes electrical means that functions to shut down certain parts of the electrical system that renders the operation of the machine automatic in case said safety circuit is closed in the manner explained, under which circumstances the cap 115 may be removed from the conduit member 110 and the metal or other matter that caused the interruption of operations may be removedythereby to open the safety circuit between the contact points.

As already mentioned, die members of different sizes are employed from time to time in die casting machines, and in order to reducethe volume of the otherwise unoccupied part of the hood S5 when relatively small die members are being used, so as to speed up evacuation of the hood, one or more displacement elements may be placed inside the hood. One such element is shown in the drawings and is designated 117, and in the present embodiment it constitutes a closure for a hand hole 118 through which access may be had to the interior of the hood. This accessibility is sometimes important for the purpose of making connections in a cooling system for the dies, which is common in die casting machines. Illustration of such a system is omitted from the instant case because it constitutes no part of the present invention.

Communicating with the interior of the hood is a suction operated switch` actuator designated 120. This `actuator, in the present instance, comprises a diaphragm and its casing, the latter being placed in communication with the interior of the hood through a pipe 121. The diaphragm, designated 122, is thus subjected to suction created within the hood and, through a stem 123, operates a switch 125, which will hereinafter be termed the hood" switch.

designates the tank of the vacuum system, and it is shown as supported by the stationary part 21 of the die casting machine. In practice, the tank, thus supported, is approximately the width of the machine, and facilities are provided for interconnecting the tanks of two or mo-re machines that are arranged side by side with an aisle between adjacent machines, so that, in effect, one tank of considerable volume is provided for a bank of machines, and it may be evacuated by means of a single suction pump, if desired. In the present illustration, the tank 130 has connection, through a pipe 134, with a suction pump 135, shown as driven by an electric mo-tor 136.

The tank 130 is placed in communication with the previously mentioned conduit member 110, through a conduit 140, the same being of suicient capacity to insure rapid evacuation of the hood 85. A so-called vacuum valve 141 is included in the conduit 140, and within the casing 142 thereof is a cylindrical chamber in which a piston 144 operates that carries the valve member 145. The valve member is biased toward open position by a spring 146, and it is shifted to closed position when pressure fluid is admitted, through a pipe 147 to the chamber 146, under the control of a pilot valve 1411. This pilot valve is of the spool type and the valve member is biased by a spring 148 to a position in which it places the pipe 147 in communication with a pipe 149 that leads to a source of pressure lluid. A solenoid 150, when energized, shifts the valve member to the position shown in Fig. 1, and when the valve member is in this position limit switch 30.

the pipe 147 is in communicationwith a pipe 151 that disposes of the Vpressure uid, as by leading it to the 10W In the present embodiment of the invention, said means consists of a vacuum breaking or air admitting valve 155 lthat communicates, through a branch conduit 156, with l-the conduit 140 between the hood or enclosure 85 and the vacuum valve 141. The valve 155 is of the'spool type, and the valve member is biased by ,a spring toward a position wherein the valve is open,

and the valve miember is shifted in opposition to the spring in order to close l the valve by a solenoid 158.

Communicating with the vacuum system between the source of suction and the Vacuum valve 141 is a suction operated switch actuator shown as consisting of a diaphrragm 160 and its casing 161, the latter being placed in communication with the conduit 140by a pipe 162. Thel diaphragm has operative connection, through a stem 163, with an electric switch 165, hereinafter referred to as the vacuum switch.

During the description of a cycle of operation of the die casting machine and vacuum apparatus, I will introduce the circuits that make up the electrical system shown in the diagram of Fig, 1 and which coordinates and controls the various steps and renders the cycle of operation automatic from start to finish. In Fig. l, the parts are j illustrated as they are related at 'the time the die members 5 and 6 are engaged with each other and a charge of molten material occupies the charging chamber 40.

As a preface to a more detailed description of the operation, I may explain that after the die members are engaged and the molten material is delivered to the charging chamber 40, the ram 75'is advanced to force Vthe material through the channel 41 into the die cavity 7, the ram advancing to within a short distance of the discharge end of the cham-ber 40, leaving a small quantity of metal in the charging chamber to solidify with the casting. In the meantime, as will more fully appear hereinafter, the gas valve 62 will have been closed, and the conduit 49 opened to the atmosphere by reason of the passage of the ram beyond the port 48, air ent-ering the housing 38 back of the ram. This admission of air permits the molten material that occupies the conduit 49 and the passages adjacent "the upper end thereof Yto gravitate toward the crucible where it will be preserved in molten condition under the influence of the heat prevailing in the region. Under the control of a timer that is a part of the electrical system, as will hereinafter appear, there is a dwell in the operation of suicient duration to permit the casting to chillV or solidify.

Next, the vacuum valve 141 is closed and the air admitting valve V155 is opened so'as to place the interior of l the hood 85 in communication with the atmosphere, p whereupon the diaphragm 122 will be relieved of suction and the hood switch 125 will close.

At this stage the mechanism will function to draw the die member 6 away from the die member 5, and the hood part 87 away from the hood part 86, the latter part now being extended by the springs 100. rAs the movable parts closely approach fully retracted position, the actuator 15 will engage the stationary abutment 16 and arrest movement of the head 10, together with the ejector pins 11 Vand the push rod 12, and, in the final movement of the die member 6, the casting will be stripped from the face thereof by the ejector pins, and may readily be removed by means of tongs, for example, inserted between the separated edges of lthe hood parts. It is evident from the construction, that the switch actuator 28 moves in unison with the die plate 2 and the parts carried thereby, and as it reaches its retracted position it opens the die open This action, as will hereinafter appear,

, positive side yof trical system to which reference has 'Y sented by a conductor 166, and the Vconductor Y clusion of the which conditionV ity remains until the next cycle is started. y I shall now describe a complete cycle of operation, and Yto begin with it will be assumed that the parts are in the positions they occupy between cycles, as indicated fragmentarily in'Fig. 2; and it may be explained that'V the the `several circuits involved in the elecbeen made -is reprenegative side,'by a to 'the diagram of system, as they are they will be intro- 167, reference` being had Fig. 1. The various circuits of the traced, will lbe designated lines, and duced as the description proceeds.

A starting switch is designated 170, and it is desirably of the push button type'and'is biased toward open position. To initiate a cycle of operation, said switch` is momentarily closed. This establishes a circuit through a line 171 that leads from the conductor 166 to the conductor 167 and includes a normally closed switch R3-2 and the winding of a relay R1. -Upon energization of the relay R1, normallyopen switches Rl-l and R1-2, incorporated in said relay, are closed. When the switch R1-1 is closed, current flows from the conductor 166 through a line 172, that includes said switch, to the former line 171, and thence to the conductor 167. This maintains the relay R1 energized, or locked in, so to speak, thereby to hold the switch R1-1 closed after the starting switch 170 has been released and allowed to open, At the same time current ows from the line 172 through a line 173, that includes the switch R1-2 and a die closing solenoid 175, said line 173 terminating at a junction 176 with the previously mentioned line 171 through a part of which the current ows tothe conductor 167 that represents the negative side of the circuit.

When theV solenoid 175 isY thus energized, it conditions the pilot valve 35a to deliver pressure fluid from a suitable source through

pipes

178 and 179 to the die Vclosing valve 35, thereby to place the latter valve in condition to convey iiuid of higher pressure to the left hand end of the cylinder 26, as the parts are viewed in Fig. l, and force the piston 25 toward the right hand end of the cylinder. sure fluid, derived from a suitable source through a pipe 180, is led to the die opening valve 36, which was left in condition to accomplish its present purpose at the conpreceding cycle, and thence through

pipes

181 and 182 to the cylinder 26.

Incidentally, as the piston 25 advances, so will the switch actuator 28, withdrawing from the die open'lim'it switch 30, allowing said switch to close. However, nothing happens at the moment as a result of the switch 30 closing7 since the circuit including said switch is open At a given point in the advancement of the piston 25, and the corresponding forward movement of the die plate 2 and hood part 87 that is carried thereby, the flange 93 of said part cornes in contact with the extended peripheral portion of the gasket 94, thus sealing the hood against the admission of air, the area of contact between said flange and gasket increasing as evacuation of the hood proceeds under conditions now to be Vdescribed.

At the moment the hood thus becomes sealed, the actuator 28 engages and closes the so-called vevacuati'ng switch 31. As a result, a circuit is established through a line 185 that includes said evacuating switch; normally closed switches 186 and Tl-A; the `beforementioned vacuum switch 165, and the vacuum solenoid 150, said line terminating at its junction 188 with the conductor 167 that constitutes the negative side of the circuit. j

When the vacuum solenoid 150 is energized, it shifts the vacuum pilot valve 141a to the position shown in Fig. l, so as to release the pressure behind the piston 144, thereby to permit the spring 146 to open the vacuum valve 141. When this valve opens it places the hood 85 in communication with the tank 130 through the conduit 140 and conduit member 110, thus to effect rapid evacuation of the hood.

Simultaneously with the opening of the vacuum valve 141, brought about by the energization of the vacuum solenoid 150, as just described, a branch circuit is established through a line 19t] that leads from its junction 191 with the previously mentioned line 185 and terminates at its junction 192 with the conductor 167, said branch circuit including the winding of the gas solenoid 70. During evacuation of the hood 85, the die member 6 continues to move toward and finally engages the die member 5, closing the die cavity 7 and entrapping in it and the charging chamber 40 a part of the highly raried atmosphere. Energization of the gas solenoid 70, resulting from the closing of the beforementioned -branch circuit represented by the line 190, shifts the pilot Valve 67 to the position shown in Fig. l in opposition to the spring 68 thereby to release the pressure back of the piston 64 and allow the spring 165 to retract the valve member 63 so as to open the gas valve 62 andpermit inert gas to flow from the bottle or tank 60 through the pipe 61 to the crucible 50 above the molten metal therein. Under the influence of such limited pressure as the inert gas is permitted to impose upon the surface of the molten material by a proper setting of the usual valve 60a associated with the tank or bottle 60, and the suction prevailing within the charging chamber 40, a measured amount of the molten material is impelled through the conduit 49, passage of the duct mem'ber 46, the orifice of the metering neans or plug 47, and the port 48, to the charging cham- The amount of time allotted to the evacuation of the hood 85 and the delivery of molten material to the charging chamber 40 is determined by an electrical timer designated T1. This instrument, when energized, performs its function after a given time interval for which the instrument is set; and the timer T1 is energized simultaneously with the closing of the evacuating switch 31 through a branch circuit represented by a line 193 that leads from its junction 194 with the line 18S, through the timer T1 to its junction 195 with the line 171 that carries the eurent to the negative side of the circuit represented by the conductor 167. It will be remembered that a part of the circuit represented by the line 185 includes the normally closed switch Tl-A. This switch, along with a normally open switch Tl-B has operative connection with the timer T1. Consequently when the timer functions, it opens switch Tl-A cutting out the vacuum solenoid 150 and the gas solenoid 70, and closes the switch T1B.

By the time the hood is fully closed and the die members are in engagement, as illustrated in Fig. 1, the actuator 2S has overridden and closed the die close limit switch 32. When this occurs a circuit is established that is represented by a line 196 having connection at the junction 197 with the line 18S and includes, lbesides the die close limit switch 32 the winding of a relay R2, the line 196 joining line 171 at the junction 176. Incorporated in the relay R2 are switches R2-1, R2-2 and R2-3, all biased toward open position. When the relay R2 is energized, these switches close. When the switch R2-1 closes, current is supplied to the relay R2 through a branch circuit represented by a line 198 that leads from line 185 to line 196 in advance of the relay, so that the relay will be locked in after the former circuit, through which current was supplied to the relay, opens.

I have previously mentionedthe fact that when the timer T1 functions, it opens the switch T1-A and closes the switch T1-B. When this latter happens a circuit is established through a line 200, that starts at its junction with the former line 185 and joins the conductor 167 at the junction designated 188, said circuit including, besides the switch Tl-B, the switch R2-2 and the so-called shot solenoid 82.

When the solenoid 82 is energized it shifts the valve member of the pilot valve a to the left, from the position shown in Fig. l, so as to direct pressure 'uid froml a suitable source (not shown) through a pipe 205 and a pipe 206 to the master valve 80, thereby to shift the member thereof to a 'position opposite that shown, so that fluid of a higher pressure is delivered through

pipes

208 and 209 to the right hand end of the shot cylinder 78. Under theseconditions, the piston 77 is advanced in the cylinder 78 so as to impel the ram 75, through the intervention of the rod 76, along the charging charnber 40 and force the molten material therefrom into the die cavity 7, the quantity of material desirably being such as will permit the ram to closely approach the outlet end of the chamber.

In the meantime, as I have explained, the vacuum solenoid and the gas solenoid 70 have been deenergized, closing the vacuum valve and shutting off the gas pressure above the molten material in the Crucible 50; and when the plunger 75, in its feeding stroke, passes the port 48, the conduit 49 will be open to the atmosphere and allow the molten material that was suspended in said conduit to ow back by gravity into the crucible, the weight of the material substantially overcoming the slight gas pressure that may remain above the molten material.

When the switch R2-3 is closed, as previously mentioned, a circuit is established through a line 210, that leads from the positive side of the circuit represented by the conductor 166, and includes said switch R2-3 and the timer T2, and joins the former line 171 at 211. a time delay sufcient to allow the metal in the die cavity and communicating spaces to chill, the timer T2 functions to close a switch T2-1, whereupon current ows through a circuit, represented 'by a line 212, that includes said switch T2-1 and a timer T3, said line joining line 171, which leads tothe negative side of the circuit, at 213. Branching from the circuit just described, ahead of the timer T3, is a circuit represented by a line 215 that connects with the aforesaid line 171 and includes the winding of a relay R3. This relay R3 includes a switch R3-1, that is biased to open position, and switches R3-2 and R3-3, that are biased to closed position. Therefore, when the timer T2 functions to close the switch T2-1-the relay R3V will be energized to close switch R3-1 and establish a circuit represented by the line 217 that includes said switch and the die open limit switch 30, current being supplied to the last mentioned circuit through the conductor 166 that represents the positive side of the circuit and has direct connection with one side of the switch 30. In other words, when the switch RES-1 closes, and so long as the die open limit switch 3] remains closed, current will flow from the conductor 166 through the switch 30 and line 217 to the junction of said line with the previously mentioned line 215 and thence through the winding of the relay R3 to the negative side of the circuit.

The consequential opening of the switch R3-2 breaks the circuit that includes the winding of the relay R1, thereby deenergizing said relay; and the opening of the switch R3-3 breaks a circuit represented by a line 21S that includes, besides said switch, one designated 219, and the solenoid 15S, thereby to deenergize the latter and allow the air admitting valve to open and admit atmospheric air to the hood. This results in relieving the diaphragm 122 of suction and permits the hood switch 125 to close.

The timer T3 now functions to close a switch rl`3-1 and establish a circuit represented by a line 220 that leads from the beforementioned line 212 ahead of the timer T3 and includes, with said switch "I3-1, the hood switch 125 and a die opening solenoid 222 that shifts the pilot valve 361L to a position `wherein it delivers pressure fluid to the die opening master valve 36, resulting in said master valve being conditioned to deliver pressure uid, through a pipe 223, to the forward end of the cylinder 26 and cause retractlon of the piston 25, and corre- After` 1 1 sponding movement of the parts operatively connected thereto, including the die plate 2 and the parts'carried thereby, such parts being shown in the position to which they are thus moved in Fig. 2. At the same time the actuator 28 will open the die open limit switch 30 and break the circuit including said switch and switch RS-I, as well as the winding'of relay R3, resulting in all circuits being reset to normal, so to speak, or their being returned to the condition they possess between cycles.

With the parts in the position shown in Fig. l2, the operator, by ymeans of'tongs, may remove the casting, spray the die members with a coolant according to usual practice, if such be desirable, and immediately thereafter close the starting switch 170 to initiate another cycleof operation. l

In the event that fugitive metal, or foreign matter having Vconductive properties, accumulates about and bridges the contact points 111 and 112, the beforementioned safety circuit thatincludes said contactV points and is represented by a line 225, is closed. This circuit also includes the winding of a so-called safety relay SVR that incorporates the previously mentioned switches 186 and 219.. When said relay is energized, therefore, it opens said switches and the respective circuits that include them, along with the vacuum solenoid 150 and air admitting solenoid 158. This insures the cutting off of Vthe hood 85 from the source of suction, and the opening of it to the atmosphere. Removal of said metal or matter in the manner previously described restores said circuits to normal condition. Y

As previously pointed out, the invention is applicable `to the handling of plastics. Therefore, it is to be understood that the term molten material as herein used, embraces plastics when in a liquid state, or when in a soft, mobile condition, regardless of how said condition is produced, whether by heat or otherwise, so long as the material is capable of flowing or-of being impelled into the die cavity and thereafter solidifying. y

Having thus described by invention, what I claim is:

l.A Apparatus incorporated in a die casting machine -of the kind including die members that are relatively movable toward and from each other and by and between which a die cavity is defined, and mechanism for effecting reverse relative movement between said die members thereby to open and close the die cavity; said apparatus comprising a two-part enclosure surrounding the die members with the parts thereof fixed with respect to the respective die members so as to be relatively movable with respect to each other with similar relative movement between the die members, extensible sealing means carried by the enclosure parts for bridging and sealing the space between said parts at the peripheral portions of said parts when the die members are a substantial distance apart, evacuating means in communication with said enclosure and which is or' sufficient capacity to create a vacuum of relatively high degree in the enclosure after said sealing means becomes effective and by the i time the die cavity is closed, a charging chamber in conlstant communication with the die cavity, a container for molten material, a cl-osure for said container, a conduit through-Which said container below the minimum molten material level therein communicates with the charging chamber, said conduit being pitched so as to drain toward the container, a source of supply of an inert gas under pressure in communication with the upper portion of said container, means activated substantially simultaneously with the closing of the die cavity for effecting delivery of the pressurized inert gas to the container, a ram reciprocable in the charging chamber which acts when projected to shut off communication between the conduit and the charging chamber and to force molten material from the chamber into the die cavity and at a given point in its progress to place said conduit in communication with the atmosphere, means for projecting and retracting theram, and further means for shutting off communication `between said source and said container thereby to allowv molten material left suspended in the conduit to drain into the container. v t

2. Apparatus incorporated in a die casting machine of the kind fi'ncluding'die members that are relatively movabletoward 'and from each other and by and between which a die cavity is defined, and mechanism for effecting reverse 'relative movement between said die members 4 thereby to open and close the die cavity; said apparatus comprising aA two-part enclosure surrounding the die members lwith the parts thereof fixed with respect to the respective dietvrnembers, extensible sealing means for bridging and sealing the space between said parts when the die members are a substantial distance apart, evacuating-means in communication with said enclosure and which is of suficient capacityl to create a vacuum of relatively high degree in the Venclosure after 'said sealing means becomes effective and by the time the die cavity is closed, .a charging chamber in constant communication with the die cavity, a container for molten material, a closure for said container, a conduit through which said container below the minimum molten material level therein communicates withfthe charging chamber, said conduitbeing pitched so as to drain toward the container, metering means in the path of flow of said material at approximately the junction of the conduit with said chargingrchamber, said means being characterized by an orifice ofza size to retard the flow and measure the desired quantity of molten material admitted to the chargingV chamber, a source of supply of an inert gas under pressure, gas conducting means leading therefrom tothe upper portion of said container, a valve in said gasconducting means, means activated to open said valve substantiallyy simultaneously with the closingV of the die cavity, a ram reciprocable in the charging chamberl which acts when projected to shut off communication between the-conduit and the charging chamber and to force molten material from the chamber into the die 'cavity and at a given point in `its progress to place said conduit incommunication with the atmosphere, means for projecting and retracting the ram, Vand further means for closing the aforesaid valve thereby to allow molten materialleft suspended in the conduit to drain into the container.

3. Vacuum apparatus incorporated in a dieV casting machine of the kind including die members relatively movable toward and from each other and by and between which a die cavity is dened, and mechanism for effecting reverse'relative movement between said die members thereby to openrand close the die cavity; said apparatus comprising an enclosure surrounding the die members that is so constructed as to be capable of being tightly closed and of being opened to afford access to the interior thereof, evacuating means, communicative connections between said evacuating means and the enclosure, a vacuum valve in said connections, a charging chamber in communication with the die cavity, a container forV molten material, means for closing said container to the atmosphere, a conduit thronghwhich said container below the minimum molten material level therein communicates with the charging chamber, means for impelling molten material from said chamber to the die cavity, a source of inert gas under pressure, communicative connections between said source and said container above the molten material therein, a gas valve in the last mentioned communicative connections, a switchv actuator operatively connected to the aforesaid mechanism of the machine so as to be moved .therebyin accord with the reverse relative movement between the die members, said enclosure having operative connection with the die members so as to open and close in a and closing movements of the die members, the enclosure becoming closed substantially in advance of the closing ofthe die cavity, electrical means for operating the aforesaid valves, an electric switch arranged in the p ath Vof said actuator so as to be engaged and closed by said actuator',

givenV relation to the openingy and electrical circuits including said valve operating means and said switch.

4. Vacuum apparatus incorporated in a die casting machine of the kind including die members relatively movable toward and from each other and by and between which a die cavity is defined, and mechanism for effecting reverse relative movement between said die members thereby to openand close the die cavity; said apparatus comprising an enclosure surounding the die members that is so constructed as to be capable of being ntightly closed and of being opened to afford access tothe interior thereof, means for evacuating the enclosure whenl in closed condition but before the die, cavity is closed, a charging chamber in communication with the die cavity, a container for molten material situated at a lower level than the charging chamber, a conduit through which said container communicates withV the, charging chamber, means effecting a transfer` of molten material from said container to the charging chamber after the die cavity is closed, means for impelling molten material from said chamber to the die cavity, an electrical control system including electrical devices operatively connected to said mechanism of the machine and to the means forimpelling the molten material from the charging chamber to the die cavity, said system coordinating the operations of said mechanism and the last mentioned means, a valve for admitting atmospheric air to the enclosure before the enclosure is opened for access to the interior thereof, electrical means for operating said valve, and a circuit that forms a part of said control system and includes said electrical means.

5. Vacuum apparatus incorporated in a die casting machine of the kind including die members relatively movable towardand from each other and by and between which a die cavity is defined, and mechanism for effec*- ing reverse relative movement between said die members thereby to open and close the die cavity; said apparatus comprising a two-part enclosure surrounding the die members with the parts thereof fixed with respect to the respective die members, sealing means for closing the space between said parts, evacuating means, communicative connections between said evacuating means and the enclosure, a valve in said communicative connections, electrical means controlling the operation of the aforesaid mechanism of the machine, a switch, an electric circuit including said electrical means and said switch, and a suction operated switch actuator operatively associated with said switch and acting7 when subjected to suction, to close the switch, said switch actuator being subjected to the suction in the aforesaid communicative connections at a location between the evacuating means and said valve.

6. Vacuum apparatus incorporated in a die casting machine of the kind including die members that are relativelymovable toward and from each other and by and between which a die cavity is defined, said machine including, also, mechanism for effecting reverse relative movement between said die members thereby to open and close the die cavity, and an instrumentality for feeding molten material to said cavity; said apparatus comprising a two-part enclosure surrounding the die members with the parts thereof fixed with respect to the respective die members, sealing means for closing the space between said parts when the parts are moved relatively toward each other, electrical means operatively associated with the aforesaid mechanism of the machine for causing the same to operate to relatively move the die members and said parts of the enclosure apart thereby to open the die cavity and the enclosure, means for opening the enclosure to the atmosphere before the die members and parts of the enclosure are moved apart, an electrical device tor operating the last mentioned means, a switch, a suction operated switch actuator having communicative connection with the enclosure, operative connections between the actuator and said switch whereby the switch is opened ldwhen said actuator is subjected to suction, the switch being closed when said actuator is relieved of suction, and a sytem of electric circuits including said switch and the aforesaid electrical means and said electrical device and so constituted as to supply current first to said device and then to said electrical means.

7. Vacuum apparatus incorporated in a die casting machine of the kind including die members relatively movable toward and from each other and by and between which a die cavity is defined, the machine including, also, mechanism for effecting reverse relative movement of said die members for opening and closing the die cavity, and an instrumentality for effecting delivery of molten metal to said cavity said apparatus comprising an enclosure surrounding the die members, means for evacuating said enclosure, and an electrical system for coordinating the operations `of and that is in operative conjunction with the aforesaid mechanism, instrumentality, and vacuum apparatus and including a normally closed switch means which, when open, suspends operation of said system, electrical contacts insulated from each other and spaced apart and located in a position to receive metal that drops from between the die members, an electrical actuator that functions, when energized, to open the aforesaid switch means, and a circuit including said contacts and said electrical actuator.

8. Vacuum apparatusincorporated in a die casting machine of the kind including diemembers relatively movable toward and from each other and by and between which a die cavity is defined, the machine including, also, mechanism for effecting reverse relative movement of said die members for opening and closing the die cavity, and an instrumentality for effecting delivery of molten material to said cavity; said apparatus comprising an enclosure surrounding the die members that is capable of being opened and closed, means for evacuating said enclosure when in closed condition, and an electrical system for coordinating the operations of and that is in operative conjunction with the aforesaid mechanism, instrumentality, and evacuating means, and which includes a circuit that controls the opening of said enclosure and permits the enclosure to be opened only when said circuit is closed, a switch in said circuit, and a suction operated actuator for said switch that is in communication with the interior of said enclosure and which acts when subjected to suction to open the switch, the switch being closed when said actuator is relieved of suction.

9. Vacuum apparatus incorporated in a die casting machine of the kind including diemembers relatively movable toward and from each other and by and between which a die cavity is defined, the machine including, also, mechanism for effecting reverse relative movement of said die members for opening and closing the die cavity, and an instrumentality for effecting delivery of molten material to said cavity; said apparatus comprising an enclosure surrounding the die members that is capable of being opened and closed, means for evacuating said enclosure when in closed condition, and an electrical system for coordinating the operations of and that is in operative conjunction with the aforesaid mechanism, instrumentality and evacuating means, and which includes a circuit that controls the opening of said enclosure and permits the enclosure to be opened only when said circuit is closed, a switch in said circuit that is biased toward closed position, and a suction operated actuator for said switch that is in communication with the interior of said enclosure and which acts when subjected to suction to hold the switch open.

10. Vacuum apparatus incorporated in a die casting machine of the kind comprising die members relatively movable toward and from each other and by and between which a die cavity is defined, the machine involving, also, mechanism for effecting reverse relative movement of said die members thereby to open and close the die cavity, and an instrumentality for effecting delivery of molten materiall to said cavity; said apparatus including an enc losure encompassing the die members, said members occupying considerably less than the whole Ainterior of said enclosure, displacement means within the enclosure that fills much of the interior of the enclosure that would otherwise be unoccupied, and means for evacuating said enclosure. l

11. Vacuum apparatus incorporated inadie casting machine of the kind comprising die members relatively movable toward and from each other and by and between which a die cavity is defined, the machine involving, also, mechanism for effecting reverse relative movement of said die members thereby to open and close the die cavity, and an instrumentality for effecting delivery of molten metal. to said cavity; said apparatus including a walled enclosure encompassing the die members, said members occupying considerably less than the whole interiorrof said enclosure, a wall of the enclosure having an access opening, a closure for said opening, displacement means carried by the closure for insertion through said opening when the closure is applied to the latter, said e displacement means filling much of the interior of the enclosure that would otherwise be unoccupied, and means for evacf uating said enclosure. i

12. Vacuum apparatus incorporated in vagdiefcasting machine of the kind comprising die members that are relatively movable toward and from each other'. and by and between which a die cavity is defined, the machine including also mechanism for effecting reverse relative movement of said die members thereby to open and close the die cavity, and an instrumentality .for effecting delivery of molten material to said cavity; said apparatus including a two-part hood that encompasses the die members, the parts whereof are fixed with respect to the respectvevdie members so as to be relatively movable with respect to each other with similar relative movement between-the die members and the parts being adapted to meet in substantially the plane of separation between `the ydie members, one of said parts being extensible and carrying seal means to engage the peripheral portion of the otherjof said parts, means biasing said one part to extended condition to engage said other part, and means for evacuating the hood when the parts Vthereofare in engagement with each other. Y p Y e 13. Vacuum apparatus incorporated in a diecasting machine of the kind comprising die members that are relatively movable toward and from each other and, by and between which a die cavity is defined, the machine including also mechanism for effecting reverserelative movement of said die members thereby to open and close the die cavity, and an instrumentality'for effecting delivery of molten material to said cavity; said apparatus including a two-part hood that encompasses the die members, the parts whereof are fixed with respect to the respective die members so as to be relatively movable with respect to each other with similar relative movement between the die members, one of said parts being characterized byV an axially extensible peripheral wall made up of rigid inner and outer end sections and an intermediate exible section, the ends of the latter section being attached to the former sections with leak-proof joints, the extensible'part being biased toward extended condition, seal means carried by the axially extensible peripheralV wall for engagement with the peripheral portion of the other of said parts to seal said two-part hood while the die members are open, and means' for evacuating the hood. v

14. Vacuum apparatus incorporated in a die casting machine of the kind comprising die members that are relatively movable toward and from each other and by and between which a die cavity is defined, the machine including also mechanism for leffecting reverse relative movement of said die members thereby to open andclose the die cavity, Yand an instrumentality for effecting de-V livery of molten material to said cavity; said apparatus including a two-part hood encompassing the die members and the parts whereof are fixed with respecttto the respective die members so as to be relatively movable withv respect to each other with similar relative movement between the die members, one of said parts being axially extensible and having a peripheral Wall that is made up of rigid inner and outer end sections and an intermediate section of flexible material, each end of which is secured with a leak-proof joint to the corersponding end section, seal means carried by said peripheral wall forv engage ment with the other of said parts while the die members are open whereby to seal said two-part hood, opposed brackets carried, respectively, by the end sections, a member secured at one end to one bracket and slidable with respect to the other bracket, resilient means compressed between the brackets and tending to move them apart, an abutment on said member beyond said other bracket for engagement by the latter to limit the extension of said hood part, and means for evacuating the hood.

References Cited in the file of this patent UNITED STATES PATENTS 698,434 Bock Apr. 29, 1902 698,591 Veedcr Apr. 29, 1902 698,593 Veedcr Apr. 29, 1902 698,596 Veedcr Apr. 29, 1902 807,072 Grimes et al. Dec. y12, 1905 1,013,548 Grey Jan. 2, 1912 1,026,733 De Buigne V May 21, 1912 1,491,964 Moxham Apr. 29, 1924 1,960,992 During May 29, 1934 2,112,343 Lester et al Mar. 29, 1938 2,195,360 vDaesen Mar. 26, 1940 2,243,835 Brunner et al. June 3, 1941 2,448,903 Miller Sept. 7, 1948 2,515,231 Kalina July 18, 1950 2,582,137 Kux Jan. 8, 1952 2,637,882 Plott May 12, 1953 2,772,012 Crabtree Nov..27, 1956 2,799,066 Federman July 16, 1957 FOREIGN PATENTSY 513,992

Canada June 21, 1955