US1948992A

US1948992A - Die-casting machine

Info

Publication number: US1948992A
Application number: US507394A
Authority: US
Inventors: Louis H Morin
Original assignee: DOEHLER DIE CASTING CO
Current assignee: DOEHLER DIE CASTING CO; DOEHLER DIE-CASTING Co
Priority date: 1931-01-08
Filing date: 1931-01-08
Publication date: 1934-02-27
Anticipated expiration: 1951-02-27

Description

DIE CASTING MACHINE 8, 1931 6 Sheets-Sheet l Filed Jan.

Feb. 27, 1934.

L. H. M'ORIN DIE CASTING MACHINE Filed Jan. 8, 1931 6 Sheets-Shegt 2 ATTORNEY Feb. 27, 1934.

Feb. 27, 1934. H. MORIN I DIE CASTING MACHINE Filed Jan. 8, 1931 6 Sheets-Sheet 4 Feb. 27, 1934. L. H. MORIN DIE CASTING MACHINE Filed Jan. 8. 1951 6 Sheets-Sheet 5 Feb. 27, 1934. H. MORIN DIE= CASTING MACHINE Filed Jan. 8, 1931 6 Sheets-Sheei 6 4 III awuemtoz I IIIIIIIII/ 'ZW Patented Feb. '27, 1934 UNITED STATES PATENT OFFICE nm-casrme momma York Application January 8, 1931. Serial No. 507,394

12 Claims.

This invention relates to that type of die-cast-' ing machines, in which the molten metal is forced into the die or mold by means of a pump comprising a stationary cylinder and a movable plunger. Such pumps for molten metal are commonly operated by means of compressed air admitted into a cylinder the piston of which is connected with the pump plunger. This of course requires multiplication and complication of apparatus and operating parts, for maintaining a supply of compressed air, together with valve devices for controlling this supply to the pump-operating cylinder. Also there is no ,convenient way for changing or varying thev amount of pressure which is to be applied to the molten metal in the mold.

in another type of automatic die-casting machines the pump for molten metal has been dispensed with and the molten metal is forced into the die or mold by means of a gaseous fluid, which most commonly and conveniently is compressed air, admitted directly into a pressure chamber forming a casting pot. This latter arrangement. while it does away with the pump, still has the complication of supplying and controlling the compressed air, together with the further objection that this air has more or less of an oxidizing effect upon the molten metal in the casting pot. This invention is embodied in a machine of the type which is directly mechanically operated from a source of power such as a driving motor, which may conveniently be an electric motor, as distinguished from another type of die-casting machines in which all or substantially all of the various operating parts or working parts are operated by means of a pressure fluid such as steam or com pressed air.

A somewhat general object of the invention is to provide an improved metal-forcing pump mechanism. A further and related object of the invention is to embody such pump mechanism directly in the working parts of the machine to beoperatedby a movable operating partthereof. -Another object is so to construct such pump mechanism that after forcing the molten metal into the die or mold this pumpmechanism will hold the molten metal in the filled mold under uniform pressure fora desired interval of time. Another object of the invention is to provide means for conveniently varying or changing such pressure at will. Another object is to provide an improved metal-forcing pump which may be readily operated in carrying out the invention as a whole. A further general object in carrying out the invention is to provide an automatic? die- Y cylinder being provided at its lower forward end with an upwardly and forwardly extending delivery duct which leads to the mold, while an inlet port for the cylinder is provided in its lower side adjacent its other end. This construction and arrangement of the pump cylinder not only provides for filling the pump cylinder with molten metal taken from a considerable depth below the surface, where the metal is clean and at a suitable high temperature, but also facilitates the convenient operation of the pump plunger by means of simplified operating mechanism.

Since the pump itself has a positive delivery, it is obvious that were this pump operated from a moving part of the machine in a positive manner with a fixed length of stroke of the pump plunger then, when the mold cavity became filled, the delivery movement of the pump plunger would be stopped and the whole machine would be stalled or some part of it broken. In carrying out the invention, means are embodied in the operating mechanism of the pump whereby when the mold cavity becomes filled with molten metal under a predetermined pressure, the forward movement of the pump plunger may cease while it still continues to hold the molten metal in the mold under the desired predetermined pressure for a suitable interval of time, after which the plunger is retracted, for filling the pump cylinder. For accomplishing this result, a movemerit-resisting yieldable pressure-applying device is connected into the operating connections between a movable operating part of the machine and the pump plunger.

More particularly and desirably, a pressure relief device of the hydraulic type is employed which will. yield at a predetermined high pressure of the molten. metal against the advancing pump plunger when the mold becomes filled, and which thereafter; while still yielding, will maintain a substantially uniform predetermined high pressure of the molten metal in the mold. Since the pressure relief device becomes operative only when the mold becomes filled with molten metal at a predetermined high pressure, the operation g weaned will remain the same with substituted molds having mold cavities of different sizes, within practical limits, of course. In further carrying out the invention, adjusting means are provided whereby the molten metal in the filled mold may be subjected to a greater or to a lesser amount of predetermined uniformly applied high pressure, as may be desired.

It is to be noted that the yieldable device referred to as a pressure relief device, does not entirely release or discontinue the pressure on themolten metal in the filled mold and pump cylinder, but it provides relief of pressure in the sense that it limits the pressure to a predetermined maximum, which is then substantially uniformly maintained while the device is yielding as the result of the delivery impulse which is being applied to the pump plunger. Thus such device is a pressure responsive device in control of the operation of the pump. This definition of terminology conveniently employed in the specification and the claims is to be hereinafter kept in mind. The invention further includes various features of construction and combinations of parts, as will appear from the following description.

One embodiment of the invention which is i1.- lustrated in the accompanying drawings will now be described, after which the invention will be pointed out in claims, reference now being had to the drawings, in which:

Fig. 1 is a side elevation as seen in Fig. 2 of one of the rotatable cam assemblies employed in carrying out the invention;

Fig. 2 is a side elevation of the machine head or power end of an automatic die-casting machine embodying the invention, with the movable operating parts of the machine in the position which they occupy between successive casting operations, or when the machine is at rest;

Fig. 3 is a similar view of the furnace end of the machine, partly in longitudinal central vertical section, Fig. 3 being a continuation of Fig. 2 from left to right, as is indicated by the vertical broken line at the right of Fig. 2 and at the left of Fig. 3;

Fig. 4 is a view similar to Fig.3, somewhat reduced, showing the casting position of the mov able operating parts there appearing;

Fig. 5 is a transverse substantially vertical section on the zig-zag line 5-5 of Fig. 2;

Fig. 6 is a similar view taken on the line 6-8 of Fig. 3;

Fig. 7 is a partial longitudinal section on the inclined line 7-7 of Fig. 2, slightly enlarged;

Fig. 8 is a slightly reduced transverse section on the inclined line 8-8 of Fig. 3:

Fig. 9 is a vertical transverse section on the zig-zag line 9--9 of Fig. 3;

Fig. 10 is a slightly enlarged partial longitudinal horizontal section on the zig-zag line l 31O of Fig. 3;

Fig. ll is a partial vertical transverse sectioz. on the line 11-11 of Fig. 3 and draw. to same scale as Fig. 10;

Fig. 12 is a similar section on the line 12--12 of Fig. 3.

In the die-casting machine shown in the drawings as an embodiment of the invention. a main frame comprises a pair of similar logitudinal channels 1 which are bolted to a series of transverse supporting benches shown as five in number, comprising three similar intermediate benches 2, a similarright-hand terminal bench 3 and a somewhat different left-hand terminal bench 4, all of these benches being shown as tied together and braced by means of a pair of longitudinal rods 5. A suitable furnace 6 is firmly secured upon the channel bars 1 toward their right-hand ends, which project to the rear beyond the furnace. The furnace has a top plate '7 firmly secured thereon and which is conveniently divided longitudinally of the machine into two complementary parts. A removable longitudinally oblong melting pot -8, in the upper part of the furnace 6, has a top flange by which it is supported upon the inner depressed margin of the top plate 7, with the upper front edge of this melting pot slightly hollowed out and extending over the top of the furnace 6.

In the die-casting machine shown in the drawings as an embodiment of the invention, a stationary die-supporting plate 9, closely adjacent to the front end of the melting pot 8, is somewhat inclined from the vertical rearwardly at its upper edge so as to overhang'the upper edge of the wall of the furnace 6 and the edge of the melting pot 8. This die-supporting plate 9 is firmly, although adjustably, secured in place to the furnace top plate 7 by means of bolts 10 passing through upstanding lugs formed on the top plate '7 and through lateral lugs formed on the die-supporting plate 9. This stationary diesupporting plate 9 is also further supported by other means as will hereinafter appear. A dieregister plate 11 is carried by the die-supporting plate 9 at the forward side or. the latter and a stationary die-section 12 covers this register plate 11 and is bolted to the die-supporting plate 9. 'An upper pair of die-frame rods 13 and a similar but longer lower pair of die-frame rods i i have their ends secured to the respective corners of the die-supporting plate 9, from which these rods extend forward at an upward inclination, as shown in the drawings (Figs. 3, 4, 8 and 9).

This die-supporting plate 9 is further supported by means of an upstanding swinging link 15. This link 15 is pivotally supported at 16 on a bracket 17 which is secured to the lower part of the front end wall of the furnace 6. The lower edge portion of the die-supporting plate 9 at each of its lateral edges is pivoted at 18 to bearing blocks 19 which, by means of screws 20, are adjustable up and down on the link 15, for raising or lowering this die-supporting plate 9. Thisswinging supporting link 15 provides for moving the die-supporting plate 9 forward away from the furnace 6 and melting pot 8 when it is desired to have access between these parts, as will presently more clearly appear. Below its pivot 16 the swinging link 15 is provided with a tail arm 21 to abut against 2. lug 22 on the bracket 17 for supporting the die plate 9 when the link 15 is swung forwardly.

An outer movable die-section 23 is bolted on the rear face of an outer or forward die-carrying plate 24 which is slidable on the die-

frame rods

13 and 14, by means of the operating mechanism of the machine, some parts of which will be hereinafter noted. thereby to withdraw the outer die section 23 away from the inner die section 12. as shown in Figs. 2 and 3 taken together, or to close this outer die-section against the inner die-section 12, in order to form a complete die or mold, as shown in Fig. 4, in which these die sections form between them a mold-cavity 25, which is provided with a gate opening 26 through the inner die section 12. It is to be understood of course, as is well known in the art, that these die 9 shown in the drawings.

sections

12 and 23 are interchangeable with other die sections to be substituted therefor and which may provide a die-cavity such as 25 of larger or smaller size, according to the size of the article to be cast, and alsov in any case providing a die.- cavity which is complementary to the configura tion or shape of the article which is to be produced by the die-casting operation.

In carrying out the invention, a pump of the positive delivery type is provided for taking molten metal from the melting pot 8 and filling the die-cavity such as 25 with such molten metal under suitable pressure. This pump has a downwardly and forwardly inclined cylinder 27, the major portion of which is immersed in or surrounded by the molten metal in the melting pot 8. This pump cylinder 2'7 is firmly and rigidly. although adjustably, supported upon the top plate '7 of the furnace 6 by means of a forward pair 28 and a rear pair 29 of side arms formed on the cylinder 27 in the same piece therewith.

This pump cylinder 27 may be adjusted forward or back by means of screws 30 in lugs 31 on the furnace cover 7, and this cylinder 27 is firmly held down in place by means of screws 32, as At its lower forward end the pump cylinder 27 has formed thereon an upward extension or neck which is provided with a delivery duct 33 which extends upwardly and forwardly and, in the particular construction shown, terminates at the top'of the melting pot 3 in a forwardly directed and slightly upwardly inclined rounded nozzle portion 34.

A casting nozzle 35 forms a forward and upwardly inclined extension from the upper end 34 of the cylinder duct 33. In the construc-- tion shown, this casting nozzle or discharge nozzle 35 is formed as a separate piece, although so far as the present invention is concerned it could be formed in the same piece with the pump cylinder 27 as an integral continuation of the upper end 34 of the delivery duct 33. The outer or forward portion of this nozzle 35 tapers and is snugly received through aligned forwardly tapering openings provided through the stationary die-supporting plate 9 and its die-register plate 11. The rear end of this nozzle 35 is of a cup shape to fit over the rounded nozzle end 34, while the forward end of this casting nozzle 35 projects slightly from the die-register plate 11 and is rounded to fit into a. cup-shaped recess in the stationary die-section 12, with the bore of this nozzle 35 in alignment with the gate opening 26, and also with the inner or rear end of this bore in alignment with the upper end portion 34 of the delivery duct 33 of the pump cylinder 2'7.

This nozzle end 35 is securely held in position by. the die-supporting plate 9 and its die-register plate 11 and is clamped at its ends between the die section 12 and the nozzle end 34 of the pump cylinder neck or duct33, and accordingly does not need to be otherwise secured or attached to the nozzle end 34 of the pump cylinder- When the stationary die-supporting plate 9 is moved forward away from the front of the furnace '6 and melting pot 8, as hereinbefore noted, this casting nozzle 35 may be readily removed for cleaning or to be replacedby a new one, as desired. At its lower side, adjacent but somewhat removed from its open or rear end, the pump cylinder 27 is provided with an inlet port 36, through which the pump cylinder 27 may be filled with molten metal taken from a considerable depth below the surface, as shown in through them a pivot rod or pin 46.

Figs. 3 and 4. The pump cylinder 27 has therein a pump plunger 3'7, which may be retracted to open the inlet port 36, as shown in Fig. 3,

or moved forward to force the molten metal into the die or mold to fill its cavity 25, as shown in Fig. 4. The open rear end of the pump cylinder 27 is shown as slightly above the level of the molten metal-in the melting pot 8.

A downwardlyand forwardly inclined plungeroperating rod 38 is in alignment with the axis of the pump cylinder 27 and is mounted for slidable operating movement through a lower forward bearing 39 which is bolted to the top of the furnace cover plate '7, and a more elevated rear bearing 40 which is bolted upon'the upper end of a bracket arm 41 which is bolted to the rear wall of the furnace 6, and which is also shown as provided with apair of lateral braces 42, the lower ends of which may be secured to the side frame channel bars 1. The pump plunger 37 and the plunger-operating rod 38 are connected together by means of a readily removable arm or coupling link 43, having at its respective ends a non-rotative detachable hook connection with the plunger 37 and its operating rod, 38, as shown in Figs. 3 and 4. In the position of the operating parts shown in Fig. 3 this coupling link 43 may be removed by simply lifting it 011?, thereby permittingthe removal of the pump plunger 37 for cleaning or for replacement by a new plunger. It will be noted that there are no obstructions above the open top of the melting pot 8, so that thereby the pump cylinder 27, its plunger 37 and connecting link 43 are all readily accessible from above. i

The plunger-operating rod 38, at a point intermediate of

itsbearings

39 and 40,'has thereon a transversely slotted yoke or cross-head 44 which provides for imparting sliding pumpoperating movement to this rod 38, this crosshead 44 desirably being formed in the same piece with the rod 38, as indicated in the drawings. In die-casting machines, in order to balance the; severe strains to which some of the operating parts are subjected, commonly many of these parts are made as virtual duplicates at opposite sides of the machine, the two parts ofsuch a pair differing from one another only in the respect of being made as right-hand and lefthand. Hereinafter, both for the sake of clarity of description and also to avoid a multiplication of reference numerals, the two members of such a pair ofparts will be designated by the same a reference numeral.

A pair of bearing blocks 45 engage and are slidable in the slot of the cross-head 44, these bearing blocks having extending transversely A substantially vertically arranged two-armed twopart. plunger-operating rocking lever 4'7 is pivoted at its upper end. on the pivot shaft 46, and intermediate of its length is pivoted on the opposite ends of a rod 48 which forms a fulcrum pivot therefor. This pivot rod 48 passes through a pair of laterally spaced bearing blocks 49 which,

through which are slightly slotted in an up and down direction. These bearing blocks are pivoted upon the ends of a pivot pin 52 which extends therethrough and is carried by the upper part of a two-part split clamp 53 which, by means of clamp bolts 54, is adjustably clamped upon a longitudinally extending slidable push rod 55 which operates the rocking lever 47 and hence the pump plunger 37. The push rod 55 is guided for sliding movement through bearings formed in the respective frame benches 2, 8 and i. This push rod 55, in the operation of the machine, is positively slid back and forth with a uniform length of stroke by the operating mechanism of the machine, through means which will presently be described.

The other or power end of the machine is provided with a machine head which carries the initial operating parts of the machine from which the several individual operating parts of the machine are operated through suitable connections, some of which have already been described. The frame of the machine head comprises a pair of side plates 56 which are firmly connected together by means of a number of transverse tie-rods 57, as well as also by means of a number of stationary tie shafts forming journals for movable operating parts, as will presently be described. These side frames 56 have bolted thereto a pair of leg brackets 58 which at their lower ends are pivoted respectively upon the opposite ends of a strong cross bar 59. This cross bar 59, adjacent the inner sides of the leg brackets 58, has thereon rollers 60 through which the machine head is supported upon forwardly and upwardly inclined tracks 61 which rest upon and are bolted to the frame channels 1, the upper inclined supporting surfaces of these tracks 61 being parallel with the inclined die-frame rods 13 and 1a.

This arrangement provides for adjusting the machine head as a whole forward and back, to-

gether with all of the parts carried thereby. In

the construction shown in the drawings, an adjusting screw 62 is threaded through the middle of the cross bar 59, from which it extends forwardly and has a reduced outer shouldered end portion journaled in a bearing 63 which is swivelled on a pivot pin 64 carried at its ends by an upstanding bracket 65, shown as formed integrally in the same piece with the adjacent left hand frame bench 4. The outer or forward end portions of the die-

frame rods

13 and 14 are supported by the plates 56 and are longitudinally adjustable relatively thereto by means of threaded portions on these rods engaged by nuts 66. This adjustment of the machine head, provided along these die-frame rods, together with the adjustment therefor provided by the adjusting screw 62, provides for the accommodation of die sections. such as 12 and 23, of different sizes, may take up more or less space between the two die-supporting plates 9 and 24. Also the adjustment provided by the adjusting screw 62 alone provides for moving forwardly the inner stationary die supporting plate 9 in the manner hereinbefore described.

The outer die-carrying plate 24 isfurzher slidably guided by means of a pair of bars 67 rigidly connected thereto to move therewith and projecting outwardly or forwardly, where they are guided for sliding movement through the side frame plates 56. In its sliding movement, between the open condition of the die or mold shown in Figs. 2 and 3 and the closed condition thereof shown in Fig. i. the slidable die-carrying plate 2 is cp erated through the intermediary of linkage connections 68, pivoted thereto and to the side frame plates 56, as shown in Figs. 2 and at.

A drive link 69, virtually forming a member of the linkage system 68, carries a pivot pin 70 atits upper end by which it is pivoted to the two similar initial or left-hand lever-forming links of this linkage 68, as shown in Figs. 2 and 5. From this upper pivotal connection 70 this drive link 69 extends downward and is provided longitudinally thereof in its lower end portion with a guide slot '71 by which this link is slidably, as well as pivotally, guided on aguide roller 72 journaled on the middle portion of a cam shaft '73, the outer end portions of which are iournaled in the slide frame plates 56. Above its guide slot 71 the drive link 69 carries a stud '74, on the re spective ends of which are 'journaled a pair of cam follower rollers 75.

These cam rollers 75 are engaged by suitably shaped cam grooves 716 in the adjacent inner sides of a pair of large transversely spaced cam gears 7'7 which are mounted upon the cam shaft '73 and are shown (Fig. 5) as keyed thereto, although in the machine shown it is only necessary to fix one of these cam gears upon the cam shaft, as will presently more clearly appear. These twin cam gears '77 operate as a unit to form a movable operating part of the machine which, through the operating connections above noted, slides the die-carrying plate 24 back and forth for closing and opening the die or mold, as well as also performing other functions in the operation of the machine as a whole, some of which will be hereinafter noted, in the carrying out of this invention. In the machine shown in the drawings, the arrangements are such that these cam gears 77 are to be rotated in a clockwise or right hand direction as viewed in Fig. 2.

The cam gears 77 are rotated through the imvtermediary of a long or double pinion 78 which has engagement with'the gear teeth of both of these cam gears at the left or front end of the machine, as shown in Figure 2. This pinion 78 is journaled upon a stationary shaft 79 which also forms a tie-rod between the two frame plates 56. An intermediate spur gear 80, fixed on the pinion 78 at the middle of its length, is accommodated between the margins of the spaced camgears 77. At its lower side the intermediate gear 80 is engaged by a drive pinion 81, fixed upon a drive shaft 82, which is journaled in bearings in the side frame plates 56. At the opposite side of the machinefrom that shown in Fig. 2, and as apears in Fig. 5, this drive shaft 82 projects beyond the adjacent side frame plate 56 and at its outer end is journaled in an outboard bearing formed in a bearing bracket 83 which is bolted to the adjaoent side frame plate 56. Adjacent its bearing in the bracket arm 83, the drive shaft 82 has a drive pulley 84 loosely rotatably mounted thereon.

This drive pulley 84 may be rotated from any convenient source of power, such for example as an electric motor (not shown) which may be conveniently mounted upon the top of the machine head T fern-led by the connected side plates 56. clutch mechanism, the details of which are not shown, is provided for clutching the drive pulley 84 to the drive shaft 82 and for disconnecting it therefrom. The clutch mechanism referred to may be manually controlled at will by means of a clutch-controlling shaft 85 which is also under the automatic control of a clutch cam 86 carried by a cam holder 87 which is fixed upon the adjacent-projecting end of the 1,948,99d' cam shaft '73, which latter is rotated by the cam gears 77, one of which, however, would be sumcient forthis purpose of rotating the clutch-controlling cam 86.

The drive shaft 82 at its otheror forward end, appearing in Fig. 2, has fixed thereon a brake drum 88. This brake drum 88 is engageable by a two-part brake band 89. The two parts or shoes 89 of this brake band are pivotally mounted on a stud 90 carried by the adjacent frame plate 56, and these brake shoes are urged towards their braking relation with the brake drum 88 by means of a pair of compression springs 91 on the outer ends of a tension link 92. ,A brake-controlling rod 93 forms a part of the connections through which the above noted brake is controlled con comitantly with thecontrol of the drive clutch mechanism, in such manner as to release this brake when the drive clutch is in engagement for operating the machine, and to apply the bralre when the drive clutch is disengaged, for thereby quickly stopping the entire machine. Although the details of the drive clutch mechanism and of the controlling mechanism therefor and for the brake are not all shown in the drawings, it might -be noted that the arrangement is such that the machine automatically stops at the end of each complete cycle, or the machine may be caused to operate continuously if so desired, and also the machine may be stopped, together with the appli cation of the brake, at any intermediate point desired, in its cycle of operation.

At a suitable distanceinward or towards the right from its bearing in the left-hand end frame bench 4, the slidable plunger-operating push rod 55 has bolted thereon a block 94 which at its sides is provided with trunnions 95 on which are pivoted the ends of a pair of operating links 96 which extend substantially horizontally outward towards the left (Fig. 2) where their ends are more widely separated, as more clearly appears in Fig. 5. These ends of the operating links 96 are pivoted respectively on pivot studs 97 which are carried by the lower ends of the two parts of a substantially vertically disposed two-part or double operating lever 98. At an intermediate point of its length the two parts of the operating lever 98 are pivoted on a stationary cross shaft 99 which also serves to tie together the lower edge portions of the side frame plates 56. The upper ends of these two parts of the operating lever are provided with inwardly projecting studs 100 on the inner ends of which cam follower rollers 101 are journaled. These cam rollers 101 are engaged in suitably shaped cam grooves 102 provided on the outer sides of the large cam gears 77.

In the particular construction shown, these cam grooves 102 are not formed directly in the body of the cam gears 77, with their cam walls in the same piece therewith. In the construction shown, the inwardly directed .outer wall of the cam groove 102 is formed by an outer cam ring. 103 which is firmly secured in place on the outer side of the cam gear 77 by means of a series of rivets 104, as shown in Fig. 1. The outwardly directed inner cam wall of the cam groove 102 is formed in part by means of a ring or collar 105 on the cam shaft 73 and in part by means of an inner cam member 106 fitting partly around the collar 105, and projecting therefrom. This inner cam member 106 is firmly anchored to the cam gear 77 by means of an interposed key 107 and -is secured in place on this cam gear by means of'a pair of screws 108, as shown in Fig. 1. As the cam gears 77 are rotated their cam grooves 102 will rock the operating lever 98, thereby to operate the pump plunger 37 through the operating con= nections which have been described. tour and relationship of the

cam grooves

76 and 102 provided by the cam gears '77 are of course such as to operate the pump plunger 37 in proper timed sequence with the operation of the other parts of the machine, including the slidable die carrying plate 2%.

It might here be noted that when the machine head, including the side frame plates 56, is to be adjusted forward or back longitudinally of the machine, as hereinbefore described, and there fore carrying with it the cam operated rocking lever 98 which operates the push rod 55, such ad justrnent is provided for by the hereinbefore described adjustable clamp 53, through which the rocking plunger-operating lever 47 connected to the push rod 55.

In carrying out the invention and as an impor= tant feature thereof, a movement-resisting yield able device is connected into the above described operating connections, from the cam gears 77 to the pump plunger 37, for operating thelatter, such device being adapted to yield under a predeterminedmaximum pressure of molten metal against the plunger 37 after the mold-cavity 25 has become filled, whereby the pump plunger 3'7! may stop its forward delivery movement while still continuing, for a predetermined interval of time. to apply a desired predetermined pressure to the molten metal in the filled mold. This feature of the invention is carried out by means of a hydraulic pressure relief device which, dur ingthe time in which. it is yielding, will apply a substantially uniform delivery impulse to the pump plunger 37, thereby correspondingly maintaining a predetermined substantially uniform pressure of the molten metal in the filled mold.

In the construction shown in the drawings, the bearing blocks i9 which carry the fulcrum pivot rod 48 forthe plunger-operating lever 47 are movably mounted to yield backwardly towards the right (Figs. 3 and 4) during the terminal portion of the delivery impulse imparted to the pump plunger 37, and these bearing blocks 49 be ing returned to their original forward position when the pump plunger 37 is drawn back or retracted. These bearing blocks 49 are guided for horizontal sliding movement in guide slots 109 formed in the laterally spaced side plates of a supporting frame 110 which at its forward end is bolted to the rear wall of the furnace 6, and which at its other or rear end has a cylinder head 111 shown as formed in the same piece therewith.

The cylinder head 111 forms a part of a liquidcontaining-pressure relief cylinder having 9. cylinder body 112 provided with feet 113 bolted down upon a base plate 114 which is bolted to the top of the right hand end frame bench 3. This cyl-' inderbody 112 and its forward or left-hand head 111 are hermetically sealed and firmly secured together by means of a series of screw studs 115. An outer orrear cylinder head 116 is similarly firmly and hermetically secured to the other end of the cylinder body 112' by means of a ser.es of screw studs 117. A pressure relief piston 118 is/contained within the cylinder body 112 and the,

is pivotally I at Milli wit H ll) nected to this fulcrum rod 48 through the intermediary of a coupling block 121, the fulcrum pivot red 48 passing through this coupling block, which fills the space between the two slidable bearing blocks 49, and the piston rod 119 having a reduced shouldered end portion passing through this coupling block 121 and firmly secured thereto by means of a terminal nut 122. It will now be obvious that the fulcrum pivot 48 of the plunger-operating lever 4'7 cannot move without also moving the pressure relief piston 118 in the closed and hermetically sealed cylinder body 112. I

A piston guide rod 123 has its inner or lefthand end firmly and rigidly secured to the inner or right-hand end of the piston rod 119, such as by means including a telescopic relation (indicated in Fig. 10) of the end portions .of these two rods, so that thereby this piston guide rod 123 forms a rigid continuation of the piston rod 119. This piston guide rod 123 passes out through the rear cylinder head 116. to which it is hermetically sealed by means of an outer packing gland 124 and also further sealed at the inner side by means of a packing device 125. The piston 118 is shown as recessed in step fashion on its inner or right-hand side, and adjacent to its hub boss, by which it is secured on the piston shaft 119, this piston has provided through it a circular series of openings or holes 126 a shown in Figs. 10 and 12.

These openings 126 are controlled, to be closed or opened, by means of a one-way valve or check valve 127, shown as in the form or a stepped valve head which is slidable inwardly or to the right on the inner end portion of the piston rod 119 in order to open the apertures 126 through the piston 118. This one-way valve 127 is urged towards its seat on the piston 118 by a coiled spring 128 which is backed up by an abutment washer 129 held on the inner reduced end portion of the piston rod 119 and abutting against a shoulder formed by the inner end of the piston guide rod 123, as shown more particularly in Fig. 10. This check valve 127 permits the piston 118 to be freely retracted in the cylinder 112 towards its cylinder head 111, or towards the left as shown in Figs. 3, 4 and 10, but prevents this piston from moving in the opposite direction so far as this valve is concerned.

The wall of the cylinder body 112 is cored out to provide longitudinally therein rather large passages 130, shown as four in number, which communicate through transverse radial notches 131 with the interior bore of the cylinder body 112 immediately adjacent to its forward cylin-,

der head 111. The other ends of these passages 130 communicate through ports 132 in the other cylinder head 116 with a cavity 133 cored out therein, as shown in the drawings. A single passage or bore 134 in the cylinder head 116 com nects the interior of the cylinder 112 with the cylinder head cavity 133, in which this bore 134 forms a valve seat. It will be noted that this valve port 134, together with the above described passages, forms a by-pass from one end of the cylinder body'112 to the other, aroundthe piston 11.8.

The valve port 134 is normally closed by means of a seated poppet valve 135 in the cylinder head cavity 133 and having an outwardly projecting valve stem 136 which is guided in a valve cage or tubular plug 137, relative to which this valve stem is sealed by means of an outerv packing gland 138. For accommodating the valvelcage.

137. the upper portion of the cylinder head 116 is provided with a projecting boss 139 having.

through it a large bore 140 which extends into the cylinder head cavity 133 in alignment with the valve port 134, which together with this bore 140 are shown as inclined downwardly in an inward direction.

The valve cage 137 is screw-threaded into the outer end portion of this bore 140 and also is provided with packing by which it is sealed therein, as shown in the drawings. The inner end portion of the valve cage 137 is reduced to provide a shoulder and a rather strong coiled thrust spring 141, surrounding this reduced portion of the valve cage 137, abuts against its shoulder and at its other or inner end bears against the valve head 135, normally holding the latter seated, for thereby closing the by-pass formed by the valve port 134. The tension or strength of this valve-closing spring 141, and therefore the amount of resistance which it offers against being unseated to open the valve port 134, may be adjusted by screwing the valve cage 137 inwardly for strengthening the spring and outward for weakening it.

Normally, that is, for use, the closed cylinder 112, together with the above described passages and cavities, is filled with a suitable oil, which for clarity of illustration is not shown in the drawings. For thus filling the cylinder it is provided at its top with an opening 142 into the adjacent passage 130. This filling opening 142 may be kept closed by means of an ordinary screw-plug if so desired, but for convenience in keeping this cylinder filled, this filling opening 142 is shown in the drawings as having con nected thereto an upstanding filling pipe 143 leading from an oil tank 144 and provided with a valve 145 of the ordinary stop-cock variety. which of course' is kept closed excepting when the pressure relief cylinder 112 is to be filled.

In its lower portion the outer or rear cylinder head 116 has a solid wallportion 146 which bridges the cylinder head cavity 133 and has provided through it a downwardly and outwardly inclined bore 147 leading from the lower part of the inside of the cylinder 112. A short pipe section 148 is screwed into the outer end of this bore 147. The outer end of this pipe section 148 carries a removable union or connector 149 for the removable attachment thereto of a small pipe or tube 150 which leads to a pressure gage, which is not shown but may be of ordinary construction and which enables the attendant of the machine at any time to note the pressure which is being applied to the oil in the cylinder 112 during the operation of the machine. Also, by disconnecting the pressure gage tube 150, the pipe section 148 may be utilized for draining the oil from the cylinder 112 when it is desired to renew such oil. Also, if desired, there may be pro vided at the top of the cylinder 112, for example in the upper portion of the outer cylinder head ,116, a small normally pluggedair-escape orifice (not shown), for more conveniently. filling the cylinder with oil.

mold-cavity, such as 25, thus becomes filled, the

the rotating cam gears 77 are still imparting a delivery impulse to the pump plunger 37 through the hereinbefore described operating connections. The result, in'the operation of the invention, is that the fulcrum pivot rod 48 for the plungeroperating lever 47 is forced backward or towards the right as viewed in Figs. 3, 4 and 10, carrying with it the pressure relief piston 118. The pressure applied by the piston 118 to the oil contained in the cylinder 112, when such pressure has reached a desired predetermined maximum, pushes open the pressure relief valve 135 againstthe resistance of itsclosing spring 141 and opens a restricted by-pass between this spring-pressed valve 135 and its seat on the valve port 134, thereby establishing a by-pass around the piston 118 from the right hand end to the left hand-end of the cylinder 112.

Since the valve 135 does not open except under the desired predetermined high pressure, this valve remains closed for holding the piston 118 stationary, with the fulcrum pivot rod as correspondingly stationary, against movement during the first stage of the complete operation while the mold-cavity 25 isbeing filled with the molten metal under the desired pressure. This pressure to be applied to the molten metal in the moldcavity 25 is regulated or determined by the above described adjustment of the valve-closing spring 141, which also similarly determines the size and thus the capacity of the restricted by-pass which this valve 135 provides when the valve-closing resistance of the spring 141 is overcome and this valve 135then permitted to open more or less, that is,- to a greater or less extent depending upon the adjusted strength of the valve spring 141.

It has been found in practice that when the by-pass valve 135 is thus forced open it will thereafter provide a substantially uniform resistance to the flow of .oil by which the backward movement of the piston 118 is permitted to take place, and therefore will cause the pump plunger 37 to apply a correspondingly uniform pressure to the molten metal in the pump cylinder 27 and die-cavity 25, this pressure being continued for adesired interval of time while the casting in the mold-cavity 25 is hardening, preparatory to the opening of the mold and the ejection of the casting by means of suitable ejector mechanism (not shown).

As soon as the pump-operating push rod 55 reaches the limit of its backward movement, which is towards the right as viewed in Figs. 2, 3 and 4, and begins to be retracted in the opposite direction, then immediately the pressure of the pump-plunger 37 on the molten metal in the pump cylinder 27 and die-cavity 25 will be released, that is, discontinued. In Fig. 4 of the drawings this pump-operating push rod 55 is shown at the limit of its movement towards the right, the pump plunger 37 having been previously stopped by the molten metal in the filled mold, while the pressure relief piston.l18 has already yielded backwardly to the full extent required, and the pressure relief valve 135 accordingly has already again closed, preparatory to the opposite or retractive movement of all oi. these'connected parts.

A back stop ring 151, desirably formed of suitable fibre, surrounds the slidable bperating rod 38 for the. pump plunger 37 between the crosshead 44 and the rear bearing 40, being shown as. adjacent to the latter. This back stop. 151 prevents the possibility of overthrow movement of the pump plunger 37 when it is retracted and also assures that the pressure relief piston 118 will be fully retracted towards the cylinder head 111. Even should the piston apertures 126 and open check valve 127 offer some resistance to the retractive movement of the pressure relief piston 118, that will have no effect whatever upon the operation, since all of the interconnected operating parts from the pump plunger 37 to the .cam gears 77 arepositively moved in this ne tractive movement, by the cams 102 carried by these cam gears 77.

The inner cam members 106 on the cam gears 77 may be convenientlyremoved and replmed through large openings 152 provided through the side frame plates 56, as shown in Fig. 2. Also it maybe noted that the leading or driving face of this cam member 106 may be cut away to a different shape if desired, for example it may be so shaped as to start the delivery movement of the pump plunger more slowly, and then to impart a gradually accelerated delivery movement there-= to.

It is obvious that various modifications may be made in the construction shown in the drawings and above particularly described, within the principle and scope of the invention as defined in the appended claims.

I claim:

1. In a die-casting machine, the combination of a positive delivery pump for forcing molten metal into a mold to fill the latter, a movable operating part of the machine, connections between the said part and the movable member of the pump for operating the latter, and a hydraulic pressure relief device embodied in the said connections and responsive to a predetermined maximum pressure of molten metal on the movable member of the pump to stop the delivery movement of the latter.

2. ma die-casting machine, the combination of a positive delivery pump for forcing molten metal into a mold to fill the latter, a movable ,operating part of the machine, connections between the said part and the movable member of the pump for operating the latter, and a hydraulic 7 pressure relief device embodied in the said connections and responsive to a predetermined maximum pressure of molten metal on the movable member of the pump to stop the delivery movement of the latter, and after the said movable member has stopped the said device being adapted to apply thereto through the said connections a substantially uniform delivery impulse for a desired length of time for thereby correspondingly maintaining a predetermined substantially uniform pressure of the molten metal in the filled mold.-

3. In a die-casting machine, the combination of a positive delivery pump for forcing molten metal into a mold to fill the latter, a movable operating part of the machine, connections between the said part and the movable member of the pump for operating the latter, a hydraulic pressure relief device embodied in the said con- ,ingly maintaining a predetermined substantially uniform pressure of the molten metal in the filled mold, and adjusting means embodied in the-said hydraulic device for rendering it responsive to a selected maximum pressure of molten metal in the pump and the filled mold and for then pre venting further increase in the said pressure.

4. In a die-casting machine, the combination of a cylinder for molten metal provided with an eduction passage leading to a mold, a plunger in the cylinder for forcing molten metal from the cylinder into the mold to fill the latter under pressure, a movable operating part of the machine, connections between the said part and the plunger to reciprocate the latter, a rocking lever included in the said connections, a yieldably movable fulcrum pivot for the said lever, a stationary liquidcontaining cylinder, a piston in the latter cylinder, a connection between the said fulcrum pivot and the said piston by which movement of the fulcrum pivot will move the piston, a normally closed pressure relief v lve in control of the movement of the piston during the delivery stroke of the plungerto open at a predetermined maximum pressure and thereafter to maintain a uniformly restricted by-pass between the opposite ends of the piston so that thereby the delivery movement of the plunger may stop and the fulcrum pivot of the said lever may yield under the control of the pressure relief valve, and a freely opening check valve to permit the free return of the piston by the said lever in the reverse movement of the latter which retracts the plunger.

5. In a die-casting machine, the combination of a cylinder for molten metal provided with an eduction passage leading to a mold, a plunger in the cylinder for forcing molten metal from the cylinder into the mold to fill the latter under pressure, a movable operating part of the machine, connections between the: said part and the plunger to reciprocate the latter, a rocking lever included in the said connections, 7 a yieldingly movable fulcrum pivot for the said lever, a stationary liquid-containing cylinder, a piston in the latter cylinder, a connection between the said fulcrum pivot and the said piston by which movement of the fulcrum pivot will move the piston, a by-pass being provided by the cylinder around the piston, a normally closed yieldable valve in control of the by-pass, a spring for holding the said valve closed with the piston stationary until the liquid in the cylinder reaches a predetermined highpressure in the delivery movement of the plunger, whereupon the valve opens sufficiently to permit the piston to move under a substantially uniform resistance which causes the plunger to apply a substantially uniform pressure to the molten 'metalin the pump cylinder and mold, means for adjusting the valve-closing spring for thereby varying the uniformly applied pressure of the pump plunger on the molten metal, and a one-way valve to permit free return movement of the piston when the pump plunger is retracted by the reverse movement of the said lever.

6. In a die-casting machine, the combination of a melting pot, a downwardlyand forwardly inclined cylinder in the melting pot provided at its lower forward end with an upwardly and forwardly extending duct leading to a mold and, provided at its lower side adjacent its other end ing lever having upper and lower lever arms of which the upper arm is connected to the said slidable rod for operating the plunger, a movable operating part of the machine, connections between the said part and the lower arm of the said lever for rockingthe latter back and forth at the proper time, a transversely movable fulcrum pivot for the said rocking lever, a piston connected to the said pivot to be moved thereby, a liquid-containing cylinder for the piston, a

.normally closed pressure relief valve for opening a restricted by-pass around the piston only at a predetermined high pressure in the delivery stroke of the plunger, and a freely opening check valve to permit unobstructed return movement of the piston and lever and plunger.

7. In a die-casting machine, the combination of a melting'pot, a rigidly supported downwardly and forwardly inclined cylinder in the melting pot having a duct leading from its lower forward end to a mold for filling the latter with molten metal from the cylinder and having an inlet port in its lower side adjacent its other end, a plunger in the cylinder, a downwardly and forwardly inclined plunger-operating rod connected to the plunger, a substantially vertically extending two-armed lever having its upper arm connected to the said slidable rod, a. slidable push rod extending longitudinally of the machine and connected to the lower end of the said lever, a substantially vertically extending two-armed operating lever having its lower end connected to the push rod for sliding the latterback and forth thereby to operate the pump plunger, a rotatable part of the machine having an operating cam in engagement with the upper end of the said operating lever, a transversely slidable fulcrum pivot for the said plunger-operating lever,

a stationarily mounted liquid-containing cylinder, a piston in the latter cylinder connected to the said fulcrum pivot to be moved thereby, a normally closed adjustable pressure relief valve in control of a-by-pass in the cylinder around the piston arranged to permit movement of the piston only at a selected predetermined high pressure of the molten metal against the pump plunger, and a freely opening by-pass valve through the piston to permit free return movement of the piston and the operating lever and the pump plunger.

8. In a die-casting machine, the combination of a melting pot, a rigidly supported cylinder for molten metal in the melting pot inclined downwardly and forwardly and having at its lower forward end an upwardly and forwardly extending duct for conveying molten metal from the cylinder into a mold to fill the latter and having an inlet port in its lower side adjacent its open rear end, a plunger in the cylinder, and means for operating the plunger to impart a delivery stroke thereto for filling the mold followed by a return stroke in which the said inlet port is uncovered for filling the cylinder from the melting.

9. In adie-casting machine, the combination of a melting pot, a rigidly supported downwardly and forwardly inclined cylinder in the melting pot having a duct leading from its lower forward nected to the said slidable rod, a slidable push rod extending longitudinally of the machine and connected to the lower end of the said lever, a substantially vertically extending two-armed operating lever having its lower end connected to the push rod for sliding the latter back and forth thereby to operate'the pump plunger, a rotatable part of the machine having an operating cam in engagement with the upper endof the said operating lever, a transversely movable fulcrum pivot for the said plunger-operating lever, and a yieldable device connected to the said movable pivot adapted to yield only under a predetermined maximum pressure of molten metal against the advancing plunger of the pump.

10. In a die-casting machine, the combination of a pump cylinder for molten metal having a delivery duct leading to a mold, a plunger in'the cylinder for forcing the molten metal from the cylinder into the mold to fill the latter, and op erating mechanism for the pump plunger including a movable part of the machine and such mechanism further including a. yieldable device connected therein to yield only under a predetermined high pressure of the molten metal against the advancing plunger, the said yieldable device comprising a. liquid-containing cylinder, a piston in the latter cylinder, a normally closed pressure relief valve for opening a. restricted by-pass around'the piston only at a predetermined high pressure in the delivery stroke of the pump plunger, a spring for holding this relief valve closed until such high pressure is reached, means for adjusting the valve-closing spring for thereby varying the pressure of the pump plunger on themolten metal in the filled mold, and a one-way valve to permit free return movement of the piston and the pump plunger when the latter is to be retracted by its said operating mechanism. I

11. In a die-casting machine, the combination of a cylinder for material to be cast provided with an eduction passage leading to a mold, a plunger in the cylinder for forcing said material from the cylinder into the mold to flll the latter under pressure, a movable operating part of the ma chine, connections between the said part and the plunger to reciprocate the latter, a rocking. lever included in the said connections, a fulcrum pivot for said lever, and a yieldable device supporting the pivot and adapted to yield only under a predetermined maximum pressure of said material against the advancing plunger of the pump.

12. In a die-casting machine, the combination of a cylinder for material to be cast provided with an eduction passage leading to a mold, a.

plunger in the cylinder for forcing said material from the cylinder into the mold to fill the latter under pressure, a movable operating part of the machine, connections between the said part and the plunger to reciprocate the latter, a rockinglever included in the said connections, a fulcrum pivot for said lever, a yieldable device forming a mounting for said pivot and adapted to yield onlyunder a predetermined maximum pressure of said material against the advancing plunger of the pump, and adjusting means embodied in the said device for rendering it responsive to a selected maximum pressure of said material in the pump and filled mold and for then preventing further increase in the said pressure.

' LOUIS n. MORIN.