US1964324A

US1964324A - Die casting machine

Info

Publication number: US1964324A
Application number: US648498A
Authority: US
Inventors: Torbjorn C Korsmo
Original assignee: Madison Kipp Corp
Current assignee: Madison Kipp Corp
Priority date: 1932-12-22
Filing date: 1932-12-22
Publication date: 1934-06-26
Anticipated expiration: 1951-06-26

Description

June 26, 1934. T. c. KORSMO DIE CASTING MACHINE Filed Dec. 22. 1932 3 Sheets-Sheet l 3nventor flfirjorn C. Eons-Mo.

Gttorneg.

June- 26, 1934. T. c. KORSMO DIE CASTING MACHINE s Sheets-Sheet 2 Filed Dec. 22, 1952 ZSnnentor C(tfornega 'June 26, 1934. T. c. KORSMO DIE CASTING-MACHINE Filed Dec. 22, 1932 SSheets-Sheet 3 Zmnentor (Ittorneg s.

Eatented June 26, 1934 DIE CASTING MACHINE Torbjorn C. Korsmo, Madison, Wis., assignor to Madison-Kipp Corporation, Madison, corporation of Wisconsin Wis., a

Application December 22, 1932, Serial No. 648,498

13 Claims.

This invention relates to die casting machines, and particularly to the pressure chamber for receiving the molten metal from the melting pot and its associated means for forcibly ejecting the metal therefrom into the die.

It is an important object of the invention to provide a completely automatic machine adapted to produce high grade castings at a rapid rate with a minimum of danger to the operator.

The invention also contemplates regulation of the speed and pressure with which the molten metal is forced into the die.- This is particularly advantageous in casting with lead and other low temperature casting metals, although the invention is in no sense limited to use of these metals.

A further object is to provide a movable pressure chamber type of machine in which power operated means for forcing the molten metal from the pressure chamber into the die are mounted directly and entirely on the pressure chamber and move therewith as a unit. This serves to eliminate the complicated operating mechanism necessary for the ejecting means when the pressure chamber is adapted to move and the operating mechanism is supported on a stationary part of the machine. It also permits changing of the pressure chamber with disturbance of a minimum number of other parts.

Another object is to provide a movable pressure chamber, metal-ejecting, plunger type of die casting machine, wherein provision is made for the pressure chamber to receive a maximum charge of molten metal from the melting pot for feeding to the die, while preventing the entry of dross from the exposed surface of the metal in the pot. Provision is also made to prevent possible splashing or spurting of the metal in the melting pot due to movement of the metal plunger on its working stroke prior to its closing the metal inlet in the pressure chamber. A specially designed liner, adapted for ready replacement when needed, is provided for that portion of the pressure chamber bore in which the metal ejecting plunger works.

In the particular embodiment of the invention hereinafter described in detail, the power operated means for forcing the metal from the pressure chamber comprises a pressure fluid actuated piston and cylinder mounted on the pressure chamber and operatively connected to a metal ejecting plunger Working in the pressure chamber bore. An automatically operated, combined inlet and exhaust valve is provided for corn trolling entry and exhaust of the motive fluid to and from opposite ends of the power cylinder so as to effect the working and return strokes and. dwell of the ejecting plunger in properly timed relation to the operation of the other parts of the machine, such as the movable pressure chamber and the movable die part.

The pressure chamber and the automatically controlled metal ejecting means of the present invention are particularly adapted for use with and are later described as embodied in a die casting machine of the general construction disclosed in the prior, application of Raymond J. Schultz, Serial No. 505,159, filed December 2'7, 1930. It will be understood, however, that the features of the present invention are not limited to use in a machine of this character, but may be applied to various other types of die casting apparatus.

In the prior machine referred to, pressure fluid is fed directly to a movable pressure chamber to force the molten metal into the die, the flow of pressure fluid to the pressure chamber being controlled by an automatically operated inlet valve, while a similarly controlled exhaust valve serves to vent the pressure fluid from the pressure chamber before the latter is disconnected from the die. With the arrangement of the present invention, the above-mentioned metal ejecting plunger type of pressure chamber, together with its power operating means for the plunger, are substituted for the pressure fluid type pressure chamber and its automatically controlledinmatic exhaust valve feature of the prior machine is utilized to provide an additional means for venting the outer end of the power cylinder for the ejecting plunger.

This valve is operated automatically to vent to the atmosphere at all times when the die is open or the goose neck is disconnected from the die. Hence, this insures that, whenever either of these conditions exists, any pressure fluid remaining in the outer end of the power cylinder from a previous operation of fluid leaking thereinto from the combination valve will be released, so as to prevent possible ejecting operation of the plunger with the attendant danger of splashing metal upon the operator. Use of this supplemental exhaust valve also facilitates rapid venting of the outer end of the power cylinder when functioning simultaneously with the combination valve, and insures such venting to permit the plunger to return in the event the combination valve exhaust should fail, due, for instance, to stoppage of the port.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which:-

Fig. 1 is a fragmentary front elevation of the machine with certain parts broken away, the die being shown closed and the pressure chamber registering therewith at the time when the ejecting plunger is just completing its working stroke to force the metal into the die. The power cylinder for the ejecting plunger and its combination valve are also shown.

Fig. 2 is a fragmentary plan of the machine with the parts in the position of Fig. 1, the standard exhaust valve and its operating means appearing at the rear of the machine together with its piped connection to the power cylinder.

Fig. 3 is a section taken on line 33 of Fig. 2 and showing the details of the standard exhaust valve and its closed condition when the parts are in the position of Fig. 1.

Fig. 4 shows, in front elevation and partial section, the position of the combination. valve and its operating means at the time the ejecting plunger is being retracted.

Fig. 5 is a view, similar to Fig. 1, showing the die open, the pressure chamber lowered to receive metal from the melting pot, and the ejecting plunger held in its fully retracted position due to the neutral position of the combination valve.

Fig. 6, which is similar to Fig. 3, but on a reduced scale, shows the open condition of the standard exhaust valve and the position of its operating means when the parts are in the position of Fig. 5.

Fig. '7 is a fragmentary section taken on line 77 of Fig. 5 to show the details of construction of the inner end of the pressure chamber and its removable liner.

Fig. 8 is a section taken on line 88 of Fig. 1.

Figs. 9, 10 and 11 are enlarged vertical, axial sections of the combination valve which show the details thereof and the corresponding positions which the valve assumes when the other parts of the machine are in the positions of Figs. 1, 4, and 5, respectively.

The machine illustrated in the drawings includes a housing 11 in which is supported the main driving shaft 12 and suitable gearing, whereby an electric motor or other appropriate means (not shown) is adapted to operate the various moving parts of the machine. Housing 11 is mounted on the base of the machine (not shown) and its wall 13 supports at one end a series of four

guide rods

14, 14, 14, 14' for the movable die part. The upper rods 14, 14' are hollow for a purpose explained later.

A hot plate 16 receives the opposite ends of

guide rods

14, 14, 14, 14'. The hot plate carries stationary part 1'7 of the die, while a frame member 18 supports the hot plate. Member 18 is forked at its lower side to straddle furnace 19 and melting pot 21, mounted on the base, and is supported itself on the base at 22, 22' for horizontal adjustment with housing 11. Attached to die carriage 15, which is mounted for reciprocation on

rods

14, 14, 14', 14' is a movable die part 20.

A pressure chamber or goose neck 23 is pivotally supported at its inner end on a pin 24 carried by a frame member 26 extending from the machine base. Goose neck 23 has a bore 27 terminating at its outer end in a combined metal-receiving and discharging nozzle 28. The nozzle end of goose neck 23 is pivotally and removably supported at 29 in a vertically reciprocable yoke 31 carried by hot plate 16, whereby the goose neck,

through movement of the yoke, may be swung downwardly about its pivot 24 to receive metal from the melting pot and then upwardly to connect the goose neck to the die.

Removably secured in the inner cylindrical end of goose neck bore 27 is a renewable liner or sleeve 32. This sleeve is provided externally intermediate its ends with a relatively wide annular groove 33 into which opens a pair of diametrically opposed metal inlet ports 34 formed in goose neck 23 (see Figs. 1 and '7). Between the upper and lower edges of groove 33 and at an appreciably higher level than that of inlet ports 34 is an annular series of four metal inlet ports 36 leading from groove 33 in sleeve 32 into the bore 37 thereof. Goose neck 23 is counterbored to receive the upper flanged end 38 of liner 32 and thereby limit its insertion into the goose neck.

Arranged for reciprocation in sleeve 32 is a metal ejecting plunger 39. A yoke 41 is rigidly, but removably,mounted upon the inner end of the goose neck and is formed with a pair of

upstanding arms

42, 43 which carry a pressure fluid cylinder 44. The lower head 46 of cylinder 44 is detachably secured thereto and is formed at either side with a perforated lug 4'7. The upper ends of

yoke arms

42, 43 are bifurcated and perforated to receive lugs 4'7, 4'7 and also

removable pins

48, 48, whereby cylinder 44 is firmly held in place, but may be readily removed when desired by removing

pins

48, 48.

The base of yoke 41 overlies the outer end of sleeve 32 to secure it in place, while a central opening 51 in the base of the yoke accommodates the outer end of the metal ejecting plunger 39.

Arranged for reciprocation in cylinder 44, by pressure fluid alternately fed to opposite ends thereof, is a piston 52 having a piston rod 53 extending through the inner end of the cylinder and connected to plunger 39. When piston 52 is at the upper end of cylinder 44, plunger 39 is raised to uncover metal inlet ports 36. With the plunger in this position and goose neck 23 lowered, as shown in Fig. 5, molten metal will flow into goose neck bore 27 by way of inlet ports 34, groove 33, and inlet ports 36, and also into nozzle 28. In operating the machine, the level 54 of the metal in melting pot 21 is always maintained so that it is above inlet ports 36 in both the raised and lowered positions of the goose neck, whereby metal is caused to flow into the goose neck through these ports whenever they are uncovered by plunger 39. When plunger 39 is moved downwardly by piston 52, which action is intended to take place only when the die is closed and the goose neck 23 connected thereto, the plunger first closes ports 36 to cut 'off the metal supply and then forcibly ejects the metal from nozzle 28 into the die. The automatically operated valve control means which feed fluid to and exhaust it from cylinder 44 to operate piston 52 and plunger 39 in properly timed relation to the movements of the goose neck and die part 20 will be described later on.

Numerous advantages flow from the construction and operation of the goose neck 23 and its liner 32 above described. This renewable liner is necessary, because of the wear and tear on the goose neck, due to the heated condition of the parts and the repeated operation of plunger 39, and the importance of having a fluid-tight joint between these parts to prevent possible escape of molten metal. Liner 32 is readily replaced after yoke 41 is detached from the goose neck and plunger 39 removed therefrom. The presence of the wide annular groove 33 enables the operator readily to bring

metal inlet ports

34 and 36 into communication with each other upon the insertion of a new liner, without the necessity of accurate registration of the ports and grooves either longitudinally or circumferentially of the sleeve.

Location of sleeve inlet ports 36 above the level of goose neck inlet ports 34 is particularly important, because this permits a maximum charge of molten metal to be received in the goose neck and thereafter discharged into the die. In prior art constructions, the goose neck inlet ports are located at a single level (generally considerably below the surface of the metal in the pot). Thus, a smaller charge is received in the goose neck and ejected therefrom than is the case with my improved construction wherein the inner end of each metal inlet passage is arranged at a higher level than its outer end. The importance of this feature in making large castings will be readily appreciated.

The ofiset arrangement of

inlet ports

34 and 36 enables ports 34 to be located considerably below the surface of the metal in melting pot 21 and thereby avoids drawing of dross into the goose neck when plunger 39 is elevated. The location of ports 34 considerably below the metal level also prevents spurting or splashing of the molten metal in themelting pot, due to ejection of metal from these ports as plunger 39 starts to descend.

The means for opening and closing the die and raising and lowering the goose neck 23 will now be described, insofar as is necessary to a complete understanding of the present invention. Further details of the operation and construction of the die operating means may be had upon reference to my prior Patents No. 1,590,246, June 29, 1926 and No. 1,631,686, June 7, 1927. Since a number of the parts involved are duplicated at the front and rear of the machine, only the front set will bedescribed and like primed reference characters used to designate corresponding parts at the rear.

Cranks 55, 55' on the ends of main drive shaft 12 have cams 56, 56' secured thereto. Each cam carries a roller 57 engaging a slot 58 in the end of a connecting rod 59. A roller 61 on connecting rod 59 constantly engages the periphery of cam 56. Cross member 62 joins the outer ends of connecting rods 59, 59' and is fixed to a pair of die carriage pusher rods 63, 63'. The ends of these rods extend through

guides

64, 64', 65, 65' located on hot plate 16 and housing wall 13.

Pusher rods 63, 63' extend freely through

split bearings

66, 66 on die carriage 15 and carry pairs of nuts 67. 67' at one side of the carriage, and

pairsof nuts

68, 68 and springs 69, 69 at the other side normally to urge the carriage against nut 67, 67'. This provides a yieldable connection between pusher rods 63, 63' and die carriage 15.

A pair of elevator pusher rods 70, 70 pivoted at one end to cross member 62, serves to operate goose neck 23. Rods '70, '70 have pin and slot connections at 71, '71. with the upper arms of a pair of bell cranks 72, 72 pivoted on frame memoer 18. The other arms of the bell cranks are pivotally connected by links 73, 73' to yoke 31 to effect the necessary movement thereof to operate goose neck 23 between its charge-receiving and die-charging positions, as will be readily understood.

Assuming the parts are in the position of Fig.

5, with the die open, plunger 39 held in raised position, and goose neck 23 lowered to receive its charge of metal through inlets 34 and nozzle 28, when power is applied to rotate shaft 12 and cranks 55, 55' clockwise, as shown in Figs. 1 and 5, connecting

rods

59, 59 are moved to the left and impart a similar movement to cross member 62, die

carriage pusher rods

63, 63 and elevator pusher rods 70, '70, This brings movable die part 20 against fixed die part 17 and raises the goose neck nozzle 28 against a perforated nipple plate '74 pivoted on die part 17 (see Fig. 1).

After the die parts are in contact,

pusher rods

63, 63 continue their movement a short distance to the left, this being permitted by the yielding of springs 69, 69'. During this short additional movement, goose neck nozzle 28 forces nipple plate 74 against the closed die. Following this plunger 39 is automatically depressed by piston 52, as appears in Fig. 1, to force the molten metal into the die.

After the parts remain in this position for a sufficient time to permit the metal in the die to freeze, plunger 39 is automatically retracted and held in this position to relieve the pressure on the metal in the goose neck before it is disconnected from the die. Continued rotation of shaft 12 then moves cross member 62, together with

pusher rods

63, 63 and '70, 70' to the right. As a result, goose neck nozzle 28 and nipple plate '74 first swing downwardly away from the die, and then, as the tension on springs 69, 69' is relieved and nuts 67, 67 re-engage die carriage 15, die part 20 is carried to the right to permit removal of the castingby the usual automatic ejecting mechanism (not shown). to the original position of Fig. 5, so that the goose neck receives a fresh charge of metal from melting pct 21 and the machine is ready to repeat indefinitely the cycle of operations just described.

The automatic valve controlled means for supplying pressure fluid to and exhausting it from power cylinder 44 will now be described. A combination feed and exhaust valve 75 for this purpose is carried by a bracket 76 mounted on hot plate 16 (see Fig. 2). The details of this valve are shown in Figs. 9, 10 and 11. The valve casing is formed with a central bore in which the valve element 77 is arranged for reciprocation. Stuffing boxes 78, '79 prevent leakage of pressure fluid between valve element 7 '7 and the casing. A pressure fluid supply pipe 80 connects to an inlet port 81 at the bottom of the valve casing, while a pair of combined inlet and

exhaust ports

82, 83 are provided at the top of the valve casing. A flexible hose 84, together with the necessary fittings, connects valve port 82 with a port 85 openmg into the bottom of cylinder 44, as shown in Fig. 8. T fitting 86 and a flexible hose 8'7 connect valve port 83 with a port 88 in the top of cylinder 44.

As a safety feature, explained in detail further on, T fitting 86 also connects by way of a pipe 89 with the standard automatically operated exhaust valve 90 provided at the rear of the machine. This valve is supported by a bracket 91 on hot plate 16. Suflice it to say for the present. that The parts have now returned U-shaped, cross passage 93, the base of which opens upon the periphery of the vlave element 77, while the legs thereof lead to spaced inlet ports 94, 95 at the top of the valve. Valve element 77 also has an exhaust passage 96 and port 96 at its outer end, and an exhaust passage 97 and port 97 at its inner end, inlet ports 94, 95 and exhaust ports 96', 97' all being ,axially aligned for periodic connection with

valve casing ports

82, 83.

Valve element 77 is adapted for movement between the metal plunger depressing position-of Fig. 9, the plunger retracting position of Fig. 10, and the intermediate, neutral position of Fig. 11 in which it cuts off both the inlet and exhaust connections to cylinder 44 to maintain plunger 39 in either its depressed or retracted position.

Fig. 9 corresponds to Fig. 1, wherein pressure fluid, as indicated by the arrows, is fed by way of passage 93 and port 95 to the upper end of cylinder 44, and the lower end of the cylinder is vented simultaneously to the atmosphere by Way of valve exhaust port 96' and passage 96 to depress plunger 39. In Fig. 11, valve element 77 has advanced slightly to the left into neutral position, at which time valve vent ports 94, 95 and exhaust ports 96', 97' are blanked to retain the fluid in cylinder 44 and thus hold plunger 39 in its raised or lowered position, whichever may be the case. In Fig. 10, valve element 77 is in its extreme left hand position for feeding fluid to the lower end of cylinder 44 by way of passage 93 and port 94 and venting the upper end of the cylinder to the atmosphere by way of valve exhaust port 97' and passage 97.

Valve element 77 is adapted for actuation by a rod 98 extending through hollow guide rod 14 and pivotally connected at its opposite end to a link 99. The latter is pivotally connected at 100 to one arm of a bell crank 101. The latter, in turn, is pivoted at 102 on housing 11. The other arm of hell crank 101 carries a roller 103 engaging a face groove 104 in a cam 105 secured on drive shaft 12.

The arrangement of cam 105 on shaft 12 and the shape of cam groove 104 are such that a portion 106 of the groove maintains valve element 77 in neutral position and thus holds plunger 39 in retracted position when the goose neck is disconnected from the die, as appears in Fig. 5. After the goose neck has received its charge and is connected to the closed die, as shown in Fig. 1, a portion 107 of cam groove 104 causes movement of valve element 77 to the plunger depressing position, whereupon plunger 39 descends and forces the metal into the die.

Cam portion 108 then moves valve element 77 to neutral position to hold plunger 39 down while the metal freezes in the die, following which a cam portion 109 causes movement of the valve element to the position of Figs. 4 and 10 to raise the plunger and again permit metal to flow into the goose neck. The goose neck then drops, the die opens, and cam portion 106 functions again to move valve element 77 to neutral position, whereby plunger 39 is held in retracted position until the next charge of metal is ejected.

The standard exhaust valve 90 at the rear of the machine, which is utilized to vent the top of cylinder 44 at certain times. comprises a casing having a hollow extension 110 connected by pipe 89 and ,hose 87 with the top of cylinder 44 (see Figs. 2 and 3). Extension 110 opens at 111 into chamber 112 of the valve casing, the outer end of which is closed by a plug 113. An atmospheric exhaust passage 114 is provided and communication between this passage and chamber 112 is controlled by a valve element 115. A spring 116 normally holds this valve closed to prevent the escape of pressure fluid.

Exhaust valve element 115 has a stem 117 projecting from the valve casing in normally spaced relation to one end of an actuating rod 118 arranged for reciprocation in hollow guide rod 14' (see Fig. 3). The opposite end of rod 118 is provided with a collar 119 between which and wall 13 is arranged a coil spring 120 to urge rod 118 constantly to the right. An adjustable head 121 on rod 118 engages one arm of a bell crank 122 pivoted at 123 on housing 11. The other arm of the bell crank carries a roller 124 which rides on the periphery of a cam 125 fixed on shaft 12.

The arrangement of cam 125 on shaft 12 and the contour of its periphery are such that the main portion 126 of the periphery operates through the mechanism described to move rod 118 to the left and thus hold standard exhaust valve element 115 open to vent the top of cylinder 44 at all times when the die is open or goose neck 23 is disconnected therefrom. Depression 127 on the periphery of cam 125 permits spring 120 to move rod 118 to the right, whereby spring 116 closes valve element 115. Closing of this valve is designed to take place after the goose neck is connected to the closed die and prior to entry of pressure fluid into the top of cylinder 44 to depress plunger 39. Plunger 39 then descends to eject the metal and remains in its lowered position for a time with standard valve element 115 still in closed position. Then, before goose neck 23 is disconnected from the closed die, combination valve element 77 operates to effect retraction of metal plunger 39, and simultaneously cam 125 functions to move valve element 115 to open position and thereby vent the top of cylinder 44.

A die casting machine provided with automatically controlled pressure fluid supplying and exhausting means arranged and operating as described above possesses the important advantage that the standard exhaust valve 90 provides for venting the upper end of power cylinder 44 at all times when the die is open or goose neck 23 is disconnected from the die. This precludes pos- 'sible metal-ejecting operation of plunger 39 at this time, due to fluid remaining in the top of the cylinder from a previous operation, or because of possible leakage of pressure fluid thereto from combination valve 75. The arrangement described also insures that the top of cylinder 44 will be vented at the proper time to permit full retraction of plunger 39. Standard exhaust valve 90 also facilitates retraction of piston 52 and plunger 39, since it is open to vent the top of cylinder 44 when combination valve 75 is held open for this purpose. Should exhaust passage 97 of combination valve 75 fail, due, for instance, to stoppage, to function at the intended time to vent the upper end of cylinder 44, such venting, nevertheless, will be effected by the standard exhaust valve 90.

It will be seen that the power operating mechanism for metal plunger 39 is mounted on and carried entirely by goose neck 23. This arrangement avoids the complicated operating mechanism necessary where use is made of a movable pressure chamber and the operating means for itsejecting plunger are supported by the melting pot or other stationary part of the machine. Goose neck 23, together with its entire plunger operating mechanism, it will be seen, may be readily removed from the machine as a unit,

I by simply removing pin 24 and disconnecting

hose sections

84 and 87 from power cylinder 44. Likewise, the power unit for plunger 39 may be quickly disconnected from the goose neck by removing

pins

48, 48. If liner 32 is to be removed, yoke 41 may be readily detached from the goose neck for this purpose.

It will be obvious that, in the operation of the machine described, variation in the speed and force with which the molten metal is displaced into the die from the goose neck may be accomplished by changing the pressure of the motive fluid supplied to pipe 80.

What is claimed is:

1. In a die casting machine having a frame, a stationary melting pot, and a die carried by the frame, the combination of a goose neck having a discharge nozzle and a metal inlet, said goose neck being pivoted on the frame for movement between a lowered position in which it is adapted to receive metal from the melting pot through the nozzle and the metal inlet and an elevated position in which the metal inlet is adapted to be closed and the metal ejected from the nozzle into the die; a metal ejecting plunger arranged for movement in the goose neck and adapted to control said metal inlet; a power cylinder carried by the goose neck; a piston in said cylinder operatively connected to the metal ejecting plunger; valve controlled means, including a valve mounted on the frame and flexible pipe connections leading from opposite ends of the power cylinder to the valve, for alternately feeding pressure fluid to and exhausting it from the ends of said cylinder to operate the plunger, whereby metal is received in the goose neck and then forced therefrom when the latter is connected to the die; and means for operating the goose neck and the valve controlled means in properly timed relation.

2. A pressure chamber unit for die casting machines including a stationary melting pot, comprising a pressure chamber having a bore terminating in a discharge nozzle at one end and provided with a metal inlet at its opposite end, said pressure chamber being adapted to be mounted in a die casting machine for movement between a charge-receiving position to receive metal through the metal inlet and the nozzle and a die-charging position; a metal ejecting plunger mountedfor movement in said opposite end of the pressure chamber bore and controlling said metal inlet; and a power cylinder and piston mounted on the pressure chamber and operatively connected to the plunger.

3. A metal I ejecting,- plunger type pressure chamber for die casting machines having a bore terminating in a discharge nozzle at one end and open at its opposite end; and a sleeve removably secured in said open end of the pressure chamber bore, said sleeve being formed with an external, annular groove into which opens an inlet port in the pressure chamber and also a port leading to the interior of the sleeve.

4. A metal ejecting, plunger type pressure chamber for die casting machines having a bore terminating in a discharge nozzle at one end and open at its opposite end; and a cylindrical liner removably secured in said open end of the pressure chamber bore, said liner being provided intermediate its ends with an external, relatively wide, annular groove into which opens a plurality of inlet ports provided in the pressure chamber and also a plurality of ports leading to the interior of the liner, said ports in the pressure chamber and the liner being offset lengthwise of the liner.

5. A metal ejecting, plunger type pressure chamber for die casting machines having a bore terminating in a discharge nozzle at one end and open at its opposite end; and a sleeve removably secured in said open end of the pressure chamber bore, said sleeve being formed with an external, annular groove into which opens an inlet port in the pressure chamber and also a port leading to the interior of the sleeve, the sleeve port being the nearer of said ports to the open end of the pressure chamber bore.

6. A metal ejecting, plunger type pressure chamber unit for die casting machines comprising a pressure chamber having a bore terminating at one end in a discharge nozzle and open at its opposite end; and a liner removably secured in said open end of the pressure chamber bore, said pressure chamber being provided with a relatively low inlet passage having its ends at substantially the same level and said liner with metal conducting means leading from said inlet passage to the interior of the liner at a substantially higher level.

7. In a die casting machine, the combination of a frame; a pressure chamber supported by the frame, said pressure chamber having a bore provided at one end with a metal discharge port; a movable metal ejecting plunger arranged in said pressure chamber; power actuated means, including a cylinder and a piston, operatively connected to the plunger; valve controlled means for alternately feeding pressure fluid to and exhausting it from said cylinder to operate the piston; additional valve controlled exhausting means adapted to vent the working end of said cylinder during the intended period of exhausting thereof by said first-mentioned valve controlled means; and means for operating both of said valve controlled means.

8. In a die casting machine, the combination of a frame; a pressure chamber mounted on said frame and having a bore terminating at one end in a metal discharge port; a die mounted on the frame, the pressure chamber and the die being arranged for relative movement between a die-charging position in which the pressure chamber and the die are connected together and a charge-receiving position in which the pressure chamber and the die are disconnected; a metal ejecting plunger arranged for reciprocation in the pressure chamber to permit entry of and to eject molten metal; power actuated means, including a cylinder and a piston, operatively connected to the plunger; valve controlled means for alternately feeding pressure fluid to and exhausting it from opposite ends of said cylinder to operate the plunger, the fluid being adapted to be fed to one end of the cylinder to impart a working stroke to the plunger and thereby force metal from the pressure chamber only when the pressure chamber and the die are connected, while said valve controlled means are adapted, during the'period of disconnection between the pressure chamber and the die, to assume a non-exhausting relation to said end of the cylinder; additional valve controlled exhausting means adapted to vent said end of the cylinder during the intended period of exhausting thereof by said first-mentioned valve controlled means and at all times when the pressure chamber and the die are disconnected; and means for effecting said relative movement of the pressure chamber and die and for operating both of said valve controlled means all in properly timed relation to each other.

9. In a die casting machine, the combination of a frame; a separable die mounted on the frame; a pressure chamber on said frame having a bore provided at one end with an outlet for the discharge of molten metal therefrom into the die; a metal ejecting plunger arranged for reciprocation in the pressure chamber to permit entry of and to eject molten metal; power actuated means, including a cylinder and a piston, operatively connected to the plunger; valve controlled means for feeding pressure fluid to and exhausting it from opposite ends of said cylinder to operate the plunger, the fluid being adapted to be fed to one end of the cylinder to impart a working stroke to the plunger and thereby force metal from the pressure chamber only when the die is closed, while said valve controlled means are adapted, during the period the die is open, to assume a non-exhausting relation to said end of the cylinder; additional valve controlled exhausting means adapted to vent said end of the cylinder during the intended period of exhausting thereof by said first-mentioned valve controlled means and at all times when the die is open; and means for opening and closing the die and for operating both of said valve controlled means all in properly timed relation to each other.

10. A metal ejecting, plunger type pressure chamber for die casting machines having a bore terminating in a discharge nozzle at one end and open at its opposite end; and a sleeve removably secured in said open end of the pressure chamber bore, said sleeve being formed with an external, substantially horizontal groove into which opens an inlet port in the pressure chamber and also a port leading to the interior of the sleeve.

11. A metal ejecting, plunger type pressure chamber for die casting machines having a bore terminating in a discharge nozzle at one end and open at its opposite end; and a cylindrical liner removably secured in said open end of the pressure chamber bore, said liner being provided intermediate its ends with an external groove into which opens an inlet port provided in the pressure chamber and a port leading to the interior of the liner, said groove extending a substantial distance lengthwise of the liner to facilitate placing said ports in communication upon insertion of the liner.

12. A liner for plunger type, die casting machine pressure chambers comprising a tubular body formed with an external annular groove and a port leading from said groove to the interior of the sleeve, said groove being adapted, when the liner is in place, to communicate with an inlet port in the pressure chamber.

13. A liner for plunger type, die casting machine pressure chambers comprising a tubular body formed with a metal conducting passage leading from the interior of the liner and adapted, when the liner is in place, to communicate with a relatively low inlet passage in the pressure chamber disposed with its ends at substantially the same level, said metal conducting passage opening into the interior of the liner at a level substantially higher than that of the inlet passage.

TORBJORN C. KORSMO.