US1515163A - Process for casting metal - Google Patents

Description

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H. A. MYERS PROCESS FOR CASTING METAL Filed Aug. 4, 1919 8 Sheets-Sheet 1 15%? "Z ens Nova 11, 1924- 1,515,163

H. A. MYERS PROCESS'FOR CASTING METAL Filed Aug. 4, 1919. a Sheets-Shet 2 Nov. 11, 1924.

A. MYERS PROCESS FOR CASTING METAL 1919 8 Sheets-Sheet 5 Filed Aug. 4

H. A. MYERS PROCESS FOR CASTING METAL Filed Aug. 4, 1919 8 Sheets-Sheet 4 Nov. 11", 1924. 7 ,515,163..

H- 'A. MYERS I PROCESS FOR CASTING METAL Fi l ed Aug. 4;, i919 a Sheets-Sheet 5 NOV, 11

H. A. MYERS PROCESS FOR CASTING METAL 8 Sheets-Sheet 6 Filed Aug. 4, 1919 lirilllillilllllll x Nov 11, 1924. i 1,515,163

H. A..'MYER$ PROCESS FOR CASTING METAL Filed Aug. 4, 1919 8 Sheets-Sheet '7' Jaye/0Z5) H. A. MYERS v PROCESS FOR CASTING METAL 191-9 8 Sheets-Sheet 8 Filed Aug. 4

Patented Nov. 11, 1924.

stares HUBERT A. MYERS, OF TOLEDO, OHIO, ASSIGNOR TO THE HUBERT A. IMIYERS COMPANY,

. OF TOLEDO, OHIO, A CORPORATION OF OHIO.

PROCESS FOR CASTING METAL.

Application filed August 4, 1919. Serial No. 315,054.

To all whom it may concern: 1

Be it known that I, HUBERT A. MYERS, a citizen of the United States of America, and a resident of Toledo, Ohio, have invented a certain new and useful Improvement in Processes for Casting Metal, of which the following is a specification.

This invention relates to the production of die castings. In the manufacture of die castings the mold for making the castings is in the nature of a die or a plurality of cooperating dies, and is used again and again, as distinguished from an ordinary mold whichis destroyed after the molten metal has cooled, so that a new mold is necessary for each casting operation.

Generally stated, therefore, the object of.

the invention is to provide an improved process or method and an apparatus for making die castings in a. rapid and economical and satisfactory manner.

A special object is to provide an improved method and means for die casting the metal in a manner that will not injure the casting, and in a way that will leave each casting, even when-made from iron or steel, with a smooth outer surface and with the hardness or softness of the metal, whichever may be desired, of the required character.

Another object of the invention is to provide a novel and improved mold to which the molten metal will not stickor adhere during the die casting operation, and from which the casting, when sufficiently cool, can be discharged easily in the required manner.

It is also an object to provide certain details and features of constructionand combinations tending to increase the general efiiciency and the desirability of a die casting apparatus and process of this particular character.

To these and other useful ends the invention consists in matters hereinafter set forth and claimed and shown in the accompanying drawings, in which Fig. 1 is a plan of a die casting apparatus embodying the principles of the invention.

Fig. 2 is a longitudinal vertical section of said apparatus.

Fig. 3 is an enlarged plan of the left %and port-ion of the apparatus shown in l ig. i is an enlarged plan of a portion of the apparatus shown at the right in Fig. 1.

Fig. 5 is a vertical lon itudinal section of the apparatus shown in ig. 3.

Fig. 6 is an enlarged vertical section of the portion of the apparatus shown at the right in Fig. 1.

igs. 7 and 8 are detail views showing casting machine for receiving the molten metal, having cooperating dies forming the molds. And, fourth, a machine for receiving the castings. from the casting machine, which may be called a cooling machine. The different machines will be described in the order mentioned.

Ta; ladle.

This machine, it will be seen, comprises a hollow metal body 1 having a refractory or heat-resisting llning 2, and provided with legs 3 to support it in any suitably elevated position. A receptacle 4 having a suitable lining 5 has its bottom provided with a downwardly. extending spindle 6 to which is fixed a worm wheel 7 whereby the ladle or receptacle 4 may be rotated about a vertical axis. worm 8 on the shaft 9, which latter is operated by an electric motor 10, or in any suitable manner. Bunsen burners 11, of any suitable character, are provided, in the manner shown, to keep the receptacle 4 hot, thereby to maintain the metal in a molten condition. A cover 12 of any suitable heatresisting material isapplied to the top of the receptacle 1, and is provided with an opening 13 through which the molten metal is poured from the spout 14, and with another opening 15 through which the metal is removed, as will hereinafter more fully This is accomplished by a arms 18, is arranged adjacent the plate 16,

in the manner shown, and is rotated, by any suitable means, so that the arms 18 will force the slag along the plate 16 and cause it to discharge from the end of the plate,

' which latter slightly overhangs the rotary receptacle. The plate 16, it will be seen, has its outer edge provided with a flange 19 which keeps the slag from falling off, and

the receptacle 4 rotates in a direction to bring the slag against the front edge 20 of the plate, and said wheel thenf; throws the slag ofl from the end 21 of said plate. Thus the rotation of the ladle not only makes it possible to always present a fresh surface of the metal to the orifice 15, but also enables the skimming device to remove the slag.

The filling machine.

This machine comprises a pedestal or base 22 having an upright hollow post 23 mounted thereon. Within this post is a vertically disposed shaft 24, to the lower end of which is fixed a worm wheel 25, the latter being engaged by the worm 26 on the shaft 27, which latter is preferably operated by a motor 28 of any suitable character. A head 29 is connected by a spline 30 with the upper end of said shaft 24, and hollow arms forming radially disposed and oppositely arranged guides 31 which are removably secured in place by screws 32, and which rotate with the head 29, are also provided whereby these guides 31 are adapted to slide up and down on the shaft 24, by reason of the spline 30, during the operation of the machine. The post 23 is provided with a cam 33, and rollers 34 are suitably mounted in the base of the rotary structure, these rollers traveling on the cam 33, so that when the rollers engage the high portions of the cam the rotary structure is raised, and when the rollers travel into the low portions of the cam the rotary structure is then lowered. Bolts or screws 35 are emploved for removably connecting the rotary structure to the head 29. so that the structure can be removed and taken apart. Each guide 31 has a slide 36 therein. Furthermore, the screws 32 serve as vertical pivots, so that the arms or guides 31 are adapted to swing about vertical axes provided by these pivots.

A cam plate 37 is mounted onthe post 23, and is provided in its upper surface with an outer cam groove 38 to engage rollers or projections 39 carried by the slides 36, and

the shape of this capo groove, as shown in Figs. 11 and 12, is such that theslides 36 are moved endwise in the desired manner head 44 at the outer end thereof containing a depending nozzle 45, which latter is preferably made of porcelain or some other material which will not only resist the heat but also the corrosive action of the molten metal. nozzle, adapted to reciprocate vertically therein. These plungers are connected with pistons 47 in the cylinders 48, the latter being supported by uprights 49 carried by the heads 44, whereby vertical reciprocation of these pistons in their cylinders causes a similar reciprocation on the part of the plungers. Each plunger preferably slides up and down in a stufling box 50 suitably provided in the upper portion of the nozzle. Fluid pressure of any suitable character is supplied to the upper and lower ends of the cylinders 48 through pipes 51 and 52, suitably connected with a source of pressure. Said pipes are provided with valves 53 and 54, of any suitable character, to control the fluid pressure, and said valves are operated by vertically disposed rods 55 connected thereto, these rods having their lower ends connected to levers 56 which are suitably .pivoted at 57 to tilt about horizontal axes.

the pivotal support for each lever being carried by the rotary structure, and being of any suitable character. A cam 58, of any suitable form or shape, is mounted on the A plunger 46 is provided for each receptacle 1, previously described, to engage one end of the lever 56, thereby to move the rod 55 upwardly, thus automatically controlling the valves. When said rod is moved upwardly, valve 53 is closed to shut off the fluid pressure to the top of the cylinder 48, and to at the same time allow the fluid pressure to escapefrom the top of the cylinder through the port 59 at the top of said valve. At the same time the valve 54 is opened to admit fluid pressure to the lower end of the cylinder 48. so that the piston 47'and the plunger 46 will be moved upwardly. The valve 54 has a similar port 60 which is open to exhaust the fluid pressure from the cylinder when the piston moves downwardly therein, as will more fully hereafter appear, it being understood that the valves are constructed for this purpose in any suitable, known or approved manner.

The casting machine.

- disposed centrally of said pgst. The lower end of said shaft has a step bearing 63, of

suitable character, and this step bearing is disposed a suitable distance from the similar step bearing 64 of the shaft 24 previously described. A head 65 is sebured to the upper end of the shaft 62, and a worm wheel 66 is secured to the lower end of said shaft, this wheel being engaged by the worm 67 on the shaft 27 previously described. A rotary turntable 69 is secured to the head 65, and arranged to rotate on the shoulder 69 formed on the center post. A cam plate 7 0 having a cam groove 71 formed therein is secured on the post 61, in any suitable manner, below the rotary turntable. The dies 72 and 73 are secured in pairs to the turntable. each pair forming a complete mold, and these molds are arranged in a circular row, in the manner shown, and are adapted to receive the molten metal to form the castings. The outer dies 7 3 are pivotally mounted on the arms 74 which project from the turntable, so that trunnion bearings 75 are formed about which the outer dies are adapted to tilt. The inner dies 72 are each secured to a horizontally reciprocating and radially arranged rod 76, each rod reciprocating in a guide 77 suitably provided on the turn-table. The inner ends of these rods are provided with rollers or projections 78 to engage the cam groove 71 previously men tioned, this groove being of a shape to cause the rods 76 to reciprocate endwise in their guides during the rotation of the turn-table. Links 79 are pivoted at 80 to the outer dies 73, above the trunnion bearings 75, and these links have slots 81 for engaging the pins or similar means 82 on the sides of the inner dies 72, whereby inward displacement of any inner die 72 will first leave the outer die 7 3 in upright position, and will then, when the pin 82 reaches the end of the slot 81, pull the outer die into a horizontal position with its inner face downward, as shown in Fig. 19, thereby to discharge the casting. The two dies have their inner faces formed with cavities to receive the molten metal, and the tops of the dies, when held together, provide openings 83 to receive the nozzles 45, alternately, of course, after each nozzle has sucked up a supply of molten metal from the ladle, and has been carried around to a position where it can then discharge the molten metal into one of the molds, as shown in Fig 5, and as will hereinafter more fully appear. Each mold carries a cam 84 for engaging the levers 56, thereby to pull the rods 55 downward, so that the valves 53 and 54 are controlled to cause the fluid pressure to "force each piston 47 downward when it arrives over one of the molds, and as soon as the corresponding nozzle below is in position to discharge the molten metal into the mold. The molds are provided with burners 85 of any suitable character, connected in any suitable manner with a source of gas pressure, to direct flames against the dies. thereby to heat the. latter to the required temperature, and to maintain them at such a temperature, so that the molten metal will not be chilled. Also, as shown, nozzles 86 are provided at the other side of each mold to direct jets of air against the dies to cool them in case they become too hot, the idea being to keep the molds at a temperature which will prevent chilling of the molten metal, so that castings of the required softness or character will be obtained, but at the same time insure sufl'icient cooling of the molten metal to insure a proper condition for the casting when it arrives at the point of discharge, so that when discharged the casting will have been cooled suificiently to keep it from losing its shape or from being distorted whendropped into the means provided for receiving the castings. A valve 87 controls the supply of gas to each pair of burners and this valve is controlled thermostatically, as by an electro-thermal device, so that the flame is automatically regulated to insure the required temperature of each mold. It will be understood that said thermostatic device may be of any suitable char acter, such as any of those employed for similar purposes, or the device may involve an instrument ofany suitable character, and is in any event governed by the heat of the mold. A similar valve 88 controls the supply of air to each. pair of nozzles 86 and is automatically controlled by a similar thermostatic device or by an electro-thermal device governed by the heat of the mold. whereby the molds are prevented from becoming either too hot or too cold, and are automatically maintained at agiven temperature or at the desired temperature. Thus there is practically no shrinkage of the molds between fillings or pourings. as successive castings are made without reducing the temperature of the molds below the point necessary for each filling, and necessary for each casting.

The cooling machine.

ployed for annealing purposes. As shown,

this machine comprises an endless belt 89 provided with guards 9O spaced apart to ill-3 form a trough for receiving the castings, the belt being suitably mounted and arranged for that purpose. A trough or pit 91 is provided in a suitable manner to contain ground or powdered mica or other material into which the castings can be dropped to prevent the metal from being hardened by the cooling process, so that the proper temper for the metal will be insured. An endless belt 9:2 is arranged to travel over rotary members 93. 9st. 95. 96, 97 and 98, and is provided with cleats or scrapers 99 adapted to carry the mica upward and discharge it onto the plate or chute 100. so that the mica or other material will be discharged into the trough formed between the plates or guards 90 previously mentioned. In this way the castings are received in the soft mica or other material. and are car ried along and allowed to cool without giving the metal too much hardness or temper, so that comparatively soft metal castings are produced, and these castings and the mica are discharged onto the shaker or rocker grate 101, the latter being operated in any suitable manner to shake the mica or other material away from the castings. leaving the latter clean and free to slide off from the end of the grate.

The operation.

From the foregoing it will be seen that while one nozzle 45 is sucking up molten metal from the rotary ladle or receptacle 4, the rotary structure 31, 36 etc., having been lowered by the cam 33 for that purpose, the other nozzle 45 is discharging its contents into one of the molds. The filling machine revolves in the direction of the arrows. shown in Figs. 11 and 12, and the casting machine revolves in the opposite direction. The cam grooves 38 and 42 are of such shape, it will be seen. that the nozzle 45 which is sucking up the molten metal from the ladle remains stationary in the opening 15 while the other nozzle 45 is discharging and traveling along with one of the molds. Fig. 12 shows the relative positions of the two nozzles when one begins to take up a charge and the other begins to discharge, and Fig. 11 shows the manner in which the nozzle which is being filled has remained stationary. notwithstanding the revolving movement of the machine. while the other nozzle has traveled a distance with the mold into which it was discharging. the molten metal. As soon as one nozzle is empty, the two heads then rise, being lifted by the action of the cam 33, and the empty nozzle re- "olves until it is over' the opening 15, and the full nozzle revolves until it is over one of the molds. and then the two heads 44 are again lowered and the operation justdescribed is repeated. This occurs for each mold of the casting machine, the worm gear- 'ing by which the filling machine and the casting machine are operated being so timed that the molds are filled successively, and the cam groove 71 causes the molds to be successively opened, thereby discharging the castings in rapid succession into the cooling machine. Referring to Figs. 9 and 10, it will be seen that each die comprises a rectangular frame having a. removable top plate 102, and the interior body portion 103 of each die, which is formed to receive the molten metal, is easily removed from said frame by removing said top plate. The die proper 103 can be made of any suitable material, but is preferably made from porcelain clay. The clay, in powdered form, such as the commercial porcelain clay em ployed for various purposes, is prepared in the usual manner and baked until it has the desired hardness, such as the porcelain employed in various articles of manufacture, or it may be either softer or harder. The dies formed in this way, and from this material or other refractory heat resisting material, can be kept very hot, at red heat if necessary, and will resist the heat of the molten metal and will prevent too sudden chilling of the metal, and the castings will be freely discharged with clean and glossy or smooth surfaces. In this way die castings are produced rapidly and in a manner that subjects each mold to practically continuous use and in a way that not only does not require cooling means to keep the molds cool, or any cooling of the mold be fore the casting is discharged therefrom, as in some previous practice, but in a manner that actually insures beneficial results from the keeping of the molds at high temperature before and during the formation of the casting, so tha-t'never at any time is the mold below its working temperature while in contact with the metal. the casting being expelled from the mold while the dies are still at high temperature and while the metal is still so hot that soft means are required to receive the castings and keep them from being distorted and from cooling too fast: and this, as stated, prevents sudden chilling of the metal and insures against too abrupt solidifying of the molten metal, resulting in the production of die castings of desirably soft metal, instead of metal which is hardened or tempered. so to speak, until it is too hard and too brittle to be satisfactory for many purposes. Ordinarily cast iron. when produced in the form of die castings. is too hard and too brittle. but the method herein described affords a way in which to convert molten iron or steel or any other metal into die castings which will have the required softness, or which will be of a malleable character. so to speak. much like the ordinary malleable iron castings. But this is accomplished directly, it

will be seen, by rapid die casting operations, so that the finished product comes directly from the cooling machine which is in the nature of a leer, and which receives the castings directly from the molding machine, so that the desirable object of producing com- )aratively soft or malleable iron castings by .he use of dies, instead of by using ordinary sand molds or similar means, is accomp-lished in a satisfactory and efiicient manner. Also, as a matter of further and special improvement, it is found that an admixture of graphite with the porcelain clay, in the making of the molds, has a beneficial result. This produces a mixture which is easily worked, and which can be given a smooth surface. In addition, it is found that the metal is still further prevented from sticking to the mold. In the making of die castings of metal, it has been the practice, more or less to keep the molds or dies cool. as they were ordinarilv made of material which would not stand the high temperature or which would produce injurious results if allowed to become highly heated. As explained, however, the preheating of the molds, in the manner described, and the maintenance of the molds at a high temperature until after the discharge of the castings, which is substantially different from previous practice, serves to prevent chilling of the metal from which castings are to be made, and results in iron or metal castings of a character previously impossible or impracticable with the die casting methods heretofore employed. In other words, the

invention contemplates the practical reversal of the previous practice and ideas on the subject, and involves the heating of the molds to a high temperature, and the allowing of the molds to remain at the temperature which they would naturally acquire from continuous use, from the heat of the molten metal, or even a higher temperature, or such temperature as is necessary to prevent sudden chilling and consequent hardening of the cast metal, which would make the castings too hard and brittle to suitable for certain purposes. Of course, after the machine has been in operation for a while, the heat of the molten metal may be suflicient to keepthe molds at the rapiire-d temperature, if the castingoperations are close enough together but if the casting machine does not revolve rapidly enough to keep each mold 1n almost constant use, then the heating attachment for each mold will automatically be brought into operation by the thermostatic control previously mentioned, thereby to keep each mold at the required temperature. When the dies of the molds are thus kept heated, from one casting operation to the next, they are not subject to alternate expanslon and contraction, such as would result from cooling the mold aftereach operation, and in this way and because of the materials employed a reasonably or comparatively long life is' ensured for the as in a cupola or other instrumentality, and

is poured into the ladle fast enough and in sufficient quantity to keep the die casting or molding machine constantly supplied, so

that each mold will receive its charge or sup- I ply of molten metal from the filling machine. whereby each mold will produce a casting for each revolution of the machine. If graphite is used in the preparation and construct-ion of the'molds, or of the dies for the molds, the mixture may be formed from one part-of graphite and three parts of porcelain, as this is found to give good results. The noz zles 45 of the filling machine can be composed of the same substance if desired, and in this connection it will be seen that the molten metal is drawn up from the receptacle 4 by a vacuum, inasmuch as the suction produced by the upward movement of the plungers 4,6 is the result of the vacuum formed inside of each nozzle. In the making of the dies for the molds, the porcelain clay can be mixed with fine sawdust, or with wheat flour. preferabl browning the latter first, and after the dies are fired or baked they are then porous. After this, the dies can be dropped into boiling oil and graphite, which will drive the graphite into the dies. In baking or firing the dies a high temperature is used, but not high enough to render the porcelain clay vitreous, the temperature being kept below this point, so that preferably each die when finished is just about hard enough to file or work easily. If this method is employed, about 15% of flour or fine sawdust can be employed, but this can be varied according to the requirements and the particular results desired. The temperature employed for baking or firing the molds can be varied, but approximately 2000 Fahrenheit has been found to give satisfactory results. which is, of course, considerably belowthe temperature necessary for vitri ing porcelain clay of this kind. If the ies are too hard, or are vitrified, they are liable to crack easily when the molds receive the molten metal; but when made soft, as explained, they canbe heated quicker without danger ofcracking and are of such character that they can be filed or cut or otherwise worked, but are not too soft to stand up in use. In practicing the process, the molds are raised to a temperature sutficient to prevent them from,

say about 1 1200 to 1400 Fahrenheit, alv hough it is found that they can be made to work. at a, muchlower temperature. Thus cracking or chilling the iron or other metal,

at no time does the molten metal encounter a cool mold, or die of low temperature, and at no time are the dies in contact with completely cooled metal, as each previously heat ed mold remains at almost an eventemperature during its use and receives hot metal and discharges hot metal therefrom during each casting operation. Also, if desired, the faces of the dies, constituting the interior surfaces of the molds, can be sprayed with black lead or graphite after each mold has been opened to discharge the casting, and before the mold is closed. For example, this can be done by means of a nozzle 104, of any suitable character, adapted to blow the lead or graphite into each mold at a certain point in the circular path of travel of the molds shown in Fig. 1, this operation occurring just after the cam groove 71 has brought the pivoted or swiveled section of the mold into vertical position. but before the two sections of the mold are brought tightly together, and while there is still space between the two sections or dies to permit the entrance between them of said nozzle, or of the jet from said nozzle, depending upon the arrangement and mode of operation desired for said nozzle. This nozzle, of course, can be operated or controlled in any suitable or desired manner, and may be entirely automatic if desired (by means of operating and controlling mechanism not shown), or .it may be inserted by hand if such is necessary or desirable. In any event, the interior of each mold is given a coating of black lead or graphite before it receives the molten metal, which tends to prevent the casting from sticking to the mold.

The thermostatic control of the valves 87 and 88 may be of any suitable character, as explained, and as indicated diagrammatically in Fig. 3, in. which the electric circuit is shown for controlling the electro-magnet (not shown), which efiects the opening and closing of the valve 87 and which is in turn controlled by the thermostatic device not shown) associated with the mold. The electro-magnetic mechanism for operating the valve 88 of each mold is, of course, provided with a circuit similar to the circuit 105, and is controlled by a thermostatic device associated with the mold, whereby these two valves are automatically controlled by the temperature of the mold. As these thermostatlc devices and automatically operated valves are old and well known, such as those made by Brown Instrument Company of Chlca-go. Illinois, nofurther illustration or description thereof is necessary.

Any suitable means, of course, may be employed for agitating the shaker grate 101 to separate the mica or other soft material from the castings. 'Ihese castings, as previously stated, produced from dies or molds composed of porcelain, have smooth and emma glossy surfaces, and the desired results in this respect are still further insured by the introduction of graphite into the pores or voids of the porcelain, when the latter is fired or baked, in the form of a mixture of of the casting when it is discharged fronr the mold, and the cooling of thecastings. throughout the process, is so gradual that the metal is not hardened. The mold with its highlyheated dies discharges its casting and is then immediately brought back into use while thus in highly heated condition. Practically, therefore, each mold is maintained at a high temperature during and between the successive casting operations per formed therein, so that each casting is discharged from a mold that is still in highly heated condition. Thus the metal is received in a hot mold and is thereafter discharged therefrom before very much cooling thereof has taken place. Preferably, as explained, the mold remains at high temperature from one casting operation to the next. received in a highly heated mold and is thereafter discharged while the mold is still hot, and perhaps hotter, thus ensuring a reasonably long life for the dies of the mold and a malleable iron or other metal casting of the desired charcter.

'Ihe pre -heating of the molds is important, of course, inasmuch as in accordance withthe invention the substance from which the dies are made is selected with special reference to its capacity or adaptability to serve its purpose better when heated than when cool, so that the dies serve their intended purpose, in every respect, much better when maintained at high temperature while alternately empty and fullthat is to say, while each mold is alternately carrying a casting and returning empty to the point where it will receive another charge of molten metal. In the production of successive die castings from the same mold, or from a series of molds, the highest efliciency is obtained, of course, when the machine is operated as rapidly as possible, so that each mold is filled and caused to discharge its casting, and is then refilled in the shortest possible space of time. Under such circumstances. therefore, the heat of the molten metal itself is calculated to maintain the molds at high temperature, and while they might be cooled or kept below a too high In any event, though, the metal is V temperature, with the dies made of any substance which works or functions better when cool than when highly heated. it is the bet-' ter plan to allow the molds to become as highly heated as they will. and to allow them to remain at such temperature. and for this reason a substance is selected for the dies which will accord with this theory and which will not only withstand the high temperature but which will actually work better and produce better results when maintained at a high temperature.

Features not claimed in this application will be claimed in divisional applications to be filed in accordance with the requirements of the Patent Office.

What I claim as my invention is 1. The process of casting metal to produce die-castings from the same mold, which. comprises the maintaining of the casting means at high temperature before and after receiving the first charge of molten metal therein, thereby to prevent sudden chilling and to fast cooling of the molten metal. as well as sudden heating of the mold. cooling the casting without cooling the mold below the temperature necessary for the formation of the next casting, and retaining the mold in heated condition to receive another charge of molten metal therein, discharging each casting while it and the mold are still in highly heated condition. thus maintaining the mold continuously at high temperature while alternately empty and full, in whichporcelain at high temperature is employed as the. casting means in direct contact with the metal to produce a casting having a smooth surface, the porcelain at said high temperature producing this elfect and allowing the metal to separate readily therefrom without sticking thereto.

2. The process of casting metal to produce successive die-castings from the same mold, which comprises the maintaining of the casting means at high temperature before and after receiving the first charge of molten metal therein. thereby to prevent sudden chilling and too fast cooling of the molten metal, as well as sudden heating of the mold, cooling the casting without cooling the mold below the temperature necessary for the formation of the next casting, and retaining the mold in heated condition to receive another charge of molten metal therein, discharging each casting while it and the mold are still in highly heated condition, thus maintaining the mold continuously at high temperature while alternately empty and full, in which porcelain at high temperature is employed as the casting means in direct contact with the metal to produce a casting having a smooth surface, the porcelain at saidhigh temperture producing this effect and allowing the metal to separate readily therefrom without sticking thereto, having'said porcelain characterized by an admixture therewith of a suflic-ient quantity of graphite to prevent the metal from sticking to the mold.

3. The process of casting metal to produce successive die-castings from the same mold, which comprises the receiving of the charge of molten metal for the first casting in high temperature forming means, .cooling the casting without cooling the mold below the temperature necessary for the next casting, discharging the casting from said means while both are still in highly heated condition. and retaining said means inheated condition for the next charge, thus maintaining said means at high temperature while. alternately empty and full. in which both artificial heat and the heat of the metal are utilized to heat the forming means.

4. The process of casting metal to produce successive die-castings from the same mold. which comprises the receiving of the charge of molten metal for the first casting in high temperature forming means, cooling the casting without cooling the mold below the temperature necessary for the next casting, discharging the casting from said means while both are still in highly heated condition, and retaining said means in heated condit on for the next charge. thus maintaining said means at high temperature while alternately empty and full, comprising the use of some refractory non-metallic substance which is previously heated to withstand the sudden heat of the molten metal and which is thus employed in direct contact with the metal in said forming means to prevent ad-v hesion of the metal thereto and for thus ensuring a smooth surface for the casting.

5. The process of casting metal to produce successive die-castings from the same mold. which comprises the gradual cooling and solidification of the first charge of liquified metal, into the desired form, by the use of previously heated forming means, not adapted when cool to withstand the sudden heat of the molten metal, without cooling the casting operations occurring so close to-' gether that the dies remain at high temperature from each operation to the next, comprising the heating of the mold before receiving the first charge of molten metal therein, to .prevent injury thereto and to the casting as well, without cooling the mold below the t mperature necessary for the next casting, and expelling each castmg while- I 1,515, we

still at high temperature and when solidified only enough to ensure against distortion thereof, in which artificial heat is employed to raise the temperature of the dies before the mold receives the first charge of metal, to guard against injury to the dies and prevent chilling of the metal, and in which the dies thus preliminarily heated remain at high temperature until after the casting is discharged therefrom.

7 The process of casting metal to make successive die-castings from the same mold, comprising the use of a substance for the dies of said mold, which substance is a nonmetallic material which is better for its purpose when maintained at high temperature than if allowed to remain cool, heating the mold before it receives the charge of molten metal, filling the mold while maintained at high temperature to prevent injury thereof, and to prevent injury of the casting, and forming the casting in a manner to prevent any disturbance of the molten metal after it enters the mold, allowing the casting to cool without cooling the mold below the temperature required for the formation of the next casting, releasing the casting while it and the mold are still at high temperature, and retaining the mold in heated condition to receive each succeeding charge therein, the high temperature being not only to ensure die-castings-of the desired character, having smooth surfaces, but also to protect the dies against injury from too sudden heating by the hot metal, said substance being porcelain and said metal being iron.

8. The process of casting metal to make successive die-castings from the same mold, comprising the use of a substance for the dies of said mold, which substance is a nonmetallic material which is better for its purpose when maintained at high temperature than if allowed to remain cool, heating the mold before it receives the charge of molten metal, filling the mold while maintained at high temperature to prevent injury thereof, and to prevent injury of the casting, and forming the casting in a manner to prevent any disturbance of the molten metal after it enters the mold, allowing the casting to cool without cooling the mold below the temperature required for the formation of the next casting, releasing the casting while it and the mold are still at high temperature, and

retaining the mold in heated condition to receive each succeeding charge therein, the high temperature being not only to ensure die-castings of the desired character, having smooth surfaces, but also to protect the dies against injury from too sudden heating by the hot metal, including the use of both artificial heat and the heat of the molten metal to maintain the mold at high temperature while thus alternately empty and full.

HlUlBlERT A. MYERS.

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