US2103995A - Metal pot for slug casting machines - Google Patents

Description

LE ROY w. wn |s Er A. 2,103,995

METAL POT FOR SLUG CASTING MACHINES Filed April 20, 1936 f. ATTORN EYS De'c. 2s, 1937.

Patented Dec. 28, 1937 i d f UNITED STATES PATENT FlCE METAL POT FOR, SLUG CASTING MACHINES poration of New York .Application April 20, 1936, Serial No. '75,476

1 Claim.

The present invention relates to improvements in metal pots for slug casting machines of the general class disclosed in U. S. Letters Patent No. 436,532 granted September 16, 1890, wherein composed lines ofcharacter bearing matrices are presented edgewise against one face of a slotted mold and a mouthpiece on the metal pot is brought against the opposite mold face in order, through the action of a spring actuated pump plunger within the pot and controlled by a rotary cam, to force molten metal outwardly through the mouthpiece of therpot into the mold slot and against the characters on the matrices 'alined along the opposite side of theV slot to thereby cast a type bar or slug.

As ordinarily constructed, the metal pot used in machines of this class comprises a reservoir portion containing a supply of molten metal, a pump well withinthe reservoir having a port for admitting metal into the well from the reservoir, and an upwardly and forwardly extending passage or throat leading from the bottom of the well, the upper end of the throat being provided with a mouthpiece, which byva forward rocking movef ment of the pct to casting position, engages at its outer side with the back of the mold. Normally, the pump plunger is held in raised or retracted position by' a controlling cam, and once during each cycle of operation of the machine, rotation of the cam brings a depressiontherein to a position which permits the plunger to descend under the influence of a powerful actuating spring and thus force the molten metal below the plunger and in the throat ahead of the plunger through one or more rows of exit holes in the mouthpiece and into the mold slot, the path of flow of the metal according to the usual previous practice, being kept as direct and free from obstructions as possible so as not to` unduly resist the force with which the metal stream enters the mold.

Since the maximum level of the metal in the pot reservoir must always be maintained somewhat'below the level of the exit or outlet holes inthe mouthpiece in order to avoid spilling of the molten metal as the pot rocks to and from casting position, it follows that there is always a volume of air in the throat of the pot abovel the normal metal level therein, even when the mouthpiece is advanced and engaged with the mold prior to the casting operation. Moreover, it iswell known that, due to exposure to the atmosphere, the molten type metal rapidly chills and oxidizes on its surface resulting in the accumulation of a surface lm of dross (lead oxides, antimony and other impurities) which varies in quantity according to the temperature at which the metal is being run and the length of time it may stand idle and which lmamounts in effect to a chilled layer separated or oating, so to speak, on the top of the hotter metal beneath.

It has been found from experience that the and of the type` face varies according to the` class of printed matter to be produced from the slugs.

While it is practically impossible to say precisely just how and to what extent the air and the dross respectively contribute to producing a detrimental effect on the slugs, the results of long experimentation point to this explanation; that the dross on the surface of the metal in the kpot throat dominates the constituency of the first charge .of metal which enters the mold and casts against the cold matrices and that. the natural cooling effect of the air and the sudden chilling of the impure metal produces on the type face imperfections commonly known as frost spots and shrinks or wrinkles which directly impair the quality of print which it is possible to obtain from the slugs. Moreover, the sudden action of the pump plunger when it is released drives the metal and the air in the throat above theA metal forwardly into the mold with such force that the air produces a strong buffing action and is trapped, except for such small quantity of air as may ese cape through small vents which are usually provided, and the air so trapped often forms slight depressions or hollows on the type face and also pockets beneath the type face and throughout the body of the slug. Such air pockets, especially those near lthe surface of the type face, frequently cause the characters'cast on the slug to cave in, especially when subjected to the pressure applied in impressing Athe characters on the slugs in stereotype paper matrices so widely used in modern printing processes.

Various expedients 'have been resorted to in attempting to correct the foregoing defects and thereby produce solid slugs with a smooth and perfect type face comparable with that of individual type. Among these expediente are ar' rangements to enable the air in the mold and pot Thus, insteadl of permitting the type metal to throat to be vented therefrom more adequately, the provision of more perfectly smooth walls and an uninterrupted path of-flow for the molten metal, and the application of a more suddenV action and greater pressure to the pump plunger to throw the metal directly into the mold and against the matrices with greater force. These expedients however have, at best, been unsuccessful, they resulting in only a small degree of improvement in solidity of the slugs or the quality of the type faces thereon under certain Working conditions and frequently, whatever improvement has been effected in one of these conditions has only been possible at the sacrice of the other.

The primary object of the present invention is to effectively overcome the aforesaid defects under all working conditions, that is, for different speeds ofV casting and for all sizes of molds and type faces.'-To this end, the invention provides means which are believed to be contrary to the 'principles heretofore considered essential to the casting of type slugs in `machines of this class.

have a direct and unobstructed path of flow, the present invention provides a deliberate interference in the form of walls orY baiiieV means so located vas to divert Vthe path of iiow of the metal stream yet not unduly reduce theV force with which the stream passes out of the mouthpiece and into the mold. It has been found that the violent churning action produced when the metal stream impinges against the balles and iiows around them under the continued action of the pump plunger causes the dross accumulationoto beinstantaneously broken up and thoroughly mixed with the hot and pure molten metal beneathits surface Vbefore the metal passes into the mold. Thus, thedross particles no longer predominate in the portion of the metal stream which rst strikes the matrix characters, and although the baflies act as a deliberate obstruction to the direct iiow of the stream of metal they are so formed and located as to allow the metal to flow around them under the full force of the pumping action. Moreover, the pressure or quantity of unvented air left in the mold is not so great nor so likely to be trapped as heretofore in undesirable hollows or pockets, theV momentaryrhesitation in the flow of Vthe metal stream by the action of the baflie means, although such hesitation is so slightgas not to retard the casting operation, permitting the air to be more completely vented before the metal enters the mold. l

VThe invention also provides balile means of the kind just described, in the form of a movable baflie member or obstruction in the path of ow of the molten metal, the arrangement of the movable baffle member being such that upon the return stroke of the pump plunger immediately following the casting operation, the baffle member will function as a valve to prevent suction of metal backwardly out of thev mold.

To these and other ends, the invention consistsV Fig. 3 is a vertical 4section on the line 3-3 in Fig. 2; Y

' Fig. 4 is a vertical section taken transversely through the mouthpiece portion of a metal pot, showing a modified form of the invention,l applied thereto;

Fig. 5; is a partial Vertical section taken on therline 5-5 in Fig. 4;

Fig. 6 is a vertical section taken transversely through the mouthpiece portion of a metal pot showing another form of the invention applied thereto, and

Fig. 7 is a partial vertical section taken on the line '1 1 in Fig. 6.

Similar parts are designated by the same rererence characters in the several figures.

The inventionv is shown in the present instance for purposes ofillustration as applied to a metal pot of the usual form employed in matrix composing and line `casting machines Vof the well known lclass hereinbefore referred to, but it will be apparent -to those skilled in the art that the invention is equally adaptable to other forms of metal pots employed for casting type bars or *slugs and'that other Vforms of baies may be employed, either directly in -the metal pot mouthpiece or inthe upper end of the metal pot throat above the type metal therein, the invention not Y being limited inthese respects except to the extent that the baffle member shall be so located prising' a cylindrical pump well 3 fitted with a pump plunger 4 which is reciprocatory vertically therein, and a passage or throat 5 which communicates with the bottom of the pump well and leads unwardly and Vforwardly therefromrto a mouthpiece 6 which forms the outlet for the metal pot. The mouthpiece is suitably secured to the upper end of the walls of the throat, as by Vscrews 'l or by a dove tail jointtightened by a wedge-shaped gib`8 as shown in Fig. 4. A side wall of the pumpwellf3 is provided with a port 9 Vwhich permits molten metal in the reservoir portion il) of the pot to flow into the well and throat portion when the pump plunger is in l raised position as shown in Fig. l. The forward or outer side vof the mouthpiece, when in casting position, engages the rear face of the mold Il having a slot I2 therein in which the type slug isto be cast against the edges of the composed line of matrices M alined along the'opposite or front face( of' the mold with their characterv f punchings M Valined at thefro-nt of the mold slot. The form of the mold and the arrangement of the metal pot whereby the latter is caused to tilt Yto and'from casting relation with'the mold, and also the arrangement Aof parts forv applying springpressure tothe piston 4 and for releasing Ythe same under control of a so-called form of slug casting machines of the classhereinbefore referred to, and it is deemed unnecessary to herein show or explain the details of construction and operation of `these parts since they are well known to thoseskilledin the art and they form no pertinent part of the present invention. f

Heretoforait has been considered essential to haveV the walls of the metal passage or throat as smooth as possible and to avoid obstructions in the path of flow of the molten metal when the pump plunger is released, inorder to allowthe streamv of molten. type metal to flow as freely as possible and with maximum velocity under the influence of the pumping action into the mold and against the edges of the matrices alined in front of the casting slot. However, it has been found that this principle of free flow of the metal stream permits the layer on the surface of the molten metal in the throat and consisting of. an

accumulation of oxidized metal or dross and impurities to dominatethe contentl 'of the first pory tion of type metal pumped into the mold and impinged against the character punchings on the matrices. Moreover, the portion of the passage or throat 5'above thednormal level of the molten metal, the average normal level' being represented in Fig. 2, contains a body of air, and the casting slot in the mold also contains a quantity of air which'varies according to the size of the casting slot. Consequently, when the pump plunger 4 is released, not only `will the accumulation of dross and impurities on'the surface of the type metal Vinvv the throat pass in more or less concentrated form directly to the matrices but4 the unobstructed ilow of the metal together with the suddenness of the pumping action will allow very little of the air ahead of the metal to escape. The result therefore lhas been that some of the air ahead of the metal stream becomes trapped in the cavities formed by the character punchings in the matrices and, to a much greater extent, forms air holes or pockets' beneath the type face and throughout the body of the cast slug. Since the matrices are ycold when' the cast is made against them, the dross' accumulation together with the hot metal immediately following it and to somev extent mixed 'with it, suddenly chills when it strikes the coldl matrices and forms frost spots and wrinkles on'the face of the type characters so that the'cast characters do not present a sufficiently smooth and` perfect surface to properly take ink for printing purposes, the imperfections being particularly evident when the slugs are used for direct printing therefrom on hard or glossy paper.

According to the present invention, the principle of. free and direct ilow of the molten type metal into the mold and against the matrices is supplanted by a principle contrary thereto and which'every effort heretofore has been made to avoid in constructing metal pots of this closs and in attempting to improve the quality of the cast slugs.

One embodiment of the present invention is shown in Figs. 1 to 3 inclusive wherein the metal pot mouthpiece B contains the usual row of exit or outlet orifices I4, the mouthpiece being provided, immediately in rear of the exit orifices, with an enlarged chamber l5 which extends longitudinally of the mouthpiece or transversely of the throat. A baille member I6 is mounted in the chamber I5 and extends along the upper wall thereof, this baflle member having a continuous rib I1 which projects downwardly therefrom into proximity with the lower wall of the chamber I5 and across the path of ow of the metal stream from the throat of the metal pot to the exit orifices of the mouthpiece. The baille member I6 is preferably constructed with a longitudinal flange portion II2L which is fitted into a recess I8 formed by an enlarged portion of the chamber I5, this recess extending longitudinally along the rear portion of the mouthpiece 6, and the" flange portion I6a is provided with a slot I9 which extends longitudinally thereof but terminates short of the ends of the flange portion Ia, this slo-t permitting free passage of metal from the throat 5 into the chamber I5'. The upper and lower walls of the slot i9 are tapered or bevelled in opposite directions so that the width of the slot opening through which the metal enters the chamber I5 is somewhat less than its width on the side toward the throat 5, and the narrow side of the slot is located at such a height that metal discharging from the throat through this slot will impinge against the face of the rib I1 which is oppo site'to the slot I9. It will thus be seen that the rib Il is positioned so that it' will effectively obstruct the direct ilow of metal from the throat 5 of .themetal pot to the mold slot I2 and that it thereby constitues a baffle against which the metal stream is compelled to impinge and around or beneath which the metal must flow before it passes through the exit orices I4 in the mouthpiece in order to enter the mold slot. 1

In the form of the invention shown in Figs. 4

and 5, the mouthpiece 2l shown is substantially the same as the one commonly employed at present on commercial slug-casting machines of the class referred to. According to this form of the invention however, the upper and lower walls of the throat-5 immediately behind the mouthpiece are oppositely bevelled to provide a flared or widened chamber 22 between the upper end of the throat 5 and the exit orifices 2Ia of the mouthpiece, and a rod 23, which may be secured at its `ends to the metal pot by screws 24, extends across the flared or widened chamber 22,`

each end of this rod being seated in a recess 25 at The rod 23 lies:

each end of the chamber 22. directly in the path of flow of molten type metal Vwhen the latter is pumped upwardly in the throat 5 and it serves the same purpose as the flange I'I previously described in connection with the baffle Imember I6, the baille in the formof the rod 23,

however, permitting the molten type metal to pass around both sides thereof.

In the form of the invention shown in Figs. 6

and 7, the mouthpiece 5 which is like that shown in Figs. l to 3 inclusive, is provided with a baille in the form of a rod 26 which extends longitudinally across the chamber VI5 in the mouthpiece, but the baille in this instance is movable instead of stationary. Instead of securing the baille to the upper end of the pot ',throat or to the mouthpiece, the mouthpiece is provided with a recess21 at each end beyond the chamber I5 in which the respective ends ofthe baille rod 26 are fitted movably, these recesses being so located as to retain the baille 26 always in direct line with the path of flow -of the molten type metal passing from thethroat 5 into the mold, but these recesses are of suflicient depth in the mouthpiece to permit the baille t0 move horizontally toward and from the upper end of the throat 5. A plate 28, corresponding substantially to the flange portion I6a of the baille member I6 and provided with a slot 29 terminating short of theV ends thereof and communicating with the throat, -serves to retain the baille rod 26 within the recesses 2l in the mouthpiece, and the forward Vside of the plate 28 is provided with a'seat 3G .into which the baille rod126 is adapted to fit when in its rear position. The plate 28 is merely seated loosely in an enlarged recess vportion of the chamber l 5, as in the case vof the baille member I6, as clearly shown in Fig. 3, it being unnecessary to secure the baille member I6V or the plate 23 rigidly in place, it being convenient not to do so Vsince they may then be'easily removed'for inspection or cleaning, by mere removal of the mouthpiece from the metal pot.

The movable'baille 26 shown in Figs. 6 and 7 functions lnot only as a baille as described but it also functions to overcome back suction of molten type metal from themold when the pump plunger is retracted or raised after the casting operation. Various schemes have 'been previously proposed for controlling the back suction of metal from the mold, as for example the arrangement of a valve immersed Within 'the metal and directly controlled by the pump plunger, as in UQS. Letters 'Patent No.- 1,732,075 granted October 15,

' 1929. The arrangement according to the present onlyV suiicient horizontal movementto presentV openings above and below it for the passage of the molten type metal when thefmetal is pumped upwardlythrough the throat 5, the force of the metal stream impinging against the baille driving it forwardly in the recesses 21 in which it is free to move, and the suction due to the partialvacuum created in ,theV throat upon the return stroke of the plunger causes the baille toV instant- `ly return to its'seat 30 in the plate 28 and thereby A'action just described will be apparentto those Vskilled in the art, it being well known that continuous .casting in one mold over long 'periods Y causes the mold toV become so hot that the slugs do "not solidify sufficiently before the return stroke 'of the 'pump plunger to prevent some of tithe metal V'at the base ofthe slugs from being z'drawnV back out of the mold, and Asuch undesirable withdrawal of unsolidied metal from the mold 'is avoided by the movable baille-functionin `as fa valve as hereinbefore described.

In v"each embodiment of the'inventionrshown,

a'baille vis provided whichY is located within a, chamber which is between the normal level of the molten metal in the throat or passage leading from the pump Welland the orirlced mouthpiece oroutlet through which the molten metal is injected into the mold,V andthe baille is elongated and extends across the width of said chamber, the latter'being preferably'o'f a Width conforming with the usual laterally widened or horizontally flared form ofthe throat, and the baille projects partially across the height V'of 4said chamberso that it 'will be Ydirectly in the path of ow of the molten metal stream'discharging from the throat and Ipassing through this chamber on its way to the outlet and the mold when the pump plunger descends to make a cast. In consequence, the streamof molten'metal will be violently churned when it strikes the baille and this churning action willbe augmented by the deflection of the flowing metal by the baille Aagainst the walls of the chamber as the metal flows around the baille on its way through the chamber, thereby causing what# ever vdrossmay lie -on the surface of the metal to berinstantly dispersed and thoroughlymixed with the hotter and pure metal under the surface,` and such 'churning action provides a momentary interval :which allows 'the air which is forced forwardly ahead vof the metal stream to be more completely vented rfrom the Imold. The resultant slugs produced in accordance with `the present invention show a marked improvement in solidity throughout vand in'quality, particularly with respect tofperfection of the surface ofthe type characters thereon, frost spots, 'hollows and wrinkles being eliminated tosuch extent Y that the slugs `are-suitable for'direct printing'on hard or glossy papen-and even in cases where the letters are of the llarger sizes, practically-al1 objec-V tionable "imperfections fare eliminated.

A metal pot for slug casting machines'having a Y metal-reservoir to'contain a body of molten metal,

a well -to receive metal lfrom `the :reservoir and having means for forcing metal therefrom, a ythroat extending upwardly from the Well to a 'level above that of the metal in the reservoir and :to a horizon-tallyelongated outlet of substantially thesame width as'the portion of the throat adjacent thereto for injecting-metal'discharged from the --throat into a slug casting -mold, a transverse chamber substantially as wide as the outletvand located between Vthe normal level of metal in the throat and .theoutletfor the flow ofrmetal there'- through, anda solid baille-extending horizontally across said-'chamber in parallel relation to the Y outlet and disposed for the ow of metal around and beyond it in at least one unbroken stream beforereaching the outlet.

VLE ROY W. WILLIS.

EDMUND M. GoQDBoDY.

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