US1645725A - Mold - Google Patents

Description

Oct. 18,1927. 1,645,725A

c. VAUGHAN MOLD Filed Nov. 20.. 1922 2 Sheens-Sheet 1 Oct. 18 1927. 1,645,725

c. VAUGHAN MOLD Filed Nov 2o, 1922 2 Sheets-Sheet 2 Patented ct. 18, 1927.

UNITED STATES 1,645,725 PATENT OFFICE.

CONRAD VAUGHAN, l0F CLEVELAND, OHIO, ASSIGNOR TO THE PERMOLD COMPANY,

OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

MOLD.

Applicationxled November 20, 1922. Serial No. 602,269.

This 4invention relates to permanent metal molds .for receiving molten metal.

While the invention is obviously of more general application in many of its aspects, it has been developed in connection with the casting of articles from aluminum or its alloys, but is equally adaptable tol any al loys having relatively high crystallization shrinkage and relatively low fusing'point The general object of the invention 1s to provide a casting apparatus for casting such alloys to yield castings in which porosity due to crystallization shrinkage .or contraction and too rapid pouring is eliminated.

A further object is to provide a mold suited to making castings having flanges or projections or having sudden variations in the cross-sectional dimensions.

A further object of the invention is to considerably shorten the time required for the casting operation, which not only gives a bigger production yield per mold per day, but also produces castings in which the phy` sical structure of the metal is of relatively 1 fine grain and relatively uniform throughout.

yAnother object of the invention is to provide a gate adapted to allow the metal. to flow at a suitable rate into the mold cavity, and to accompany this by simultaneously cooling the molten metal remote from the gate or that in heavy or thick sections of the casting. Thus the freezing of the metal takes place progressively'toward the gate and the metal in the mold cavity remains liquid between the .point where solidification is taking place and the gate. The new metal coiniiig through the gate comes at such a rate into the mold cavity that it will not be filled so rapidly that the metal in the gate or in any thin parts of the casting near the gate will be frozen before the metal solidiiies in the more remote or thicker parts of the mold cavity, and thus prevent feeding of the metal through the gate when solidification slirinkage is taking place in the metal in the mold cavity. This `overcomes the objection sometimes encountered in other molds where themetal of the thin part solidifies before the metal in the thicker part of t-he casting and thus prevents proper feeding of the metal in the thicker part upon solidification and contraction. Without such feeding, the' contraction causes a drawing away from the already solid metal of the thin part, resulting in cracking of the castin or uneven shrinking of the casting from the mold walls causing depressions in the casting, or both.

While it is an object of this invention to provide a relatively small gate to control the rate of flow into the casting cavity, it is also an object of this invention to provide agate which, due to its shape, will prevent piping and will improve the physical characteristics of the metal in the casting adjacent the gate.

Another object of the invention is to provide ,a mold in which the amount of molten metal required inthe sprue is greatly reduced as a considerable cooling of the metal in the mold cavity is accomplished before the hot molten metal fills the sprue cavity. A relatively smaller amount of metal is therefore needed in the sprue cavity to feed the casting on account of the fact that there has been considerable cooling in the mold cavity and part of the shrinkage has already t-aken place in the mold cavity before the sprue cavity is filled, and also because the freezing of the metal in the mold cavity is controlled so that it is progressive toward the gate, so that Huid communication is maintained between the sprue cavity and the unfrozen parts of the casting in the mold cavity.

Another object of the invention is to provide a relatively simple means for cooling the portions of the mold distant from the gate to facilitate freezing.

Other objects of the invention are to provide an ejector mechanism for discharging thehot casting from the mold and to provide artificial cooling means for such ejectors, so that they will not deface the surface of the cast-ing or fracture the casting when ejecting it from the mold.

A further object of the invention is to provide a mold with relatively movable sections and relativelysimple and eticient actuating means therefor which can be quickly and easily operated to hold the sections together ormove them apart.

Other objects will be apparent from the following description and annexed drawings.

Reference should be had to the accompanying drawings forming a part of this specification in which Figure l is a top plan view of the casting ap aratus.

ig. 2 is a side elevation of the apparatus.

sus-

3 is -a section on line 3-3 of Fig. 1.

Fig. 4 is a section on line 4-4 of Figl. 3. Fig. 5 is a side elevation of a slig tly modified form of the invention.

Referring to the annexed drawings, the mold and actuating members for the mold arts are mounted upon a base member or d plate 1. The mold may be made of any suitable material and consists of a xed section 2, secured to the bed plate, and a movable section V3, slidable in a guideway 4 on the base member 1. Such guideway may be of the usual T-section to rigidly hold the Vslidable section 3 from tipping. The fixed section 2 has the face thereof, which is presented to the movable section, recessed to provide the casting cavities 5 and a sprue cavity 6 and T-shaped feed openings or gates 7 leading from 4the sprue cavity to the casting cavity. The movable section 3 has a' fiat face on the side thereof toward the fixed section which fits against the recessed face of the fixed section. A. core-8 may be attached to the face of the movable section 3 to project into the casting recesses 5. A threaded bar 9 is' pivoted to the outer side of the movable mold section 3, adjacent the base thereof, and carries a nut 10 upon its outer end, which has handles 11 fixed thereto and is formed with a wide bearing groove 12 having side walls or opposing shoulders 12a and 12b. An open yoke 13 is fixed tothe end of the base member 1 and is adapted to receive the grooved portion 12 of the nut 10. When the nut 10 is seated in the yoke 13, the yoke forms a thrust bearing for the nut so that by turnin the nut in one direction the shoulder 12b ears against the yoke and forces the bar 9 to move the section 3 until it is clamped tightly against the fixed section 2. After a casting has been made, the nut 10 can be turned in the opposite direction by means of the handles 11, so that the shoulder 12a bears against the yoke and pulls the mold section 3 away from the section 2, freeingit of the casting. The nut may then be rotated or the section 3 moved so that the screw 9 may be lifted free of the yoke 13 in order`that the movable section 3 can be quickly pulled entirely away from the fixed section 2.

The fixed section 2 is provided with an ejecting mechanism consisting of a series of plungers 14 slidably fitted in the rear wall thereof and at the back of each casting recess 5. During the operation of casting, these plungers are in withdrawn position so that their ends are flush with the wall of the recess and form a part thereof. The plungers e 14 in the present disclosure are rigidly secured to a cross bar 15 which carries a pair of rearwardly extending rack bars 16. Theseare engaged by an elongated pinion 17 journaled in a suitable bracket 18 at the rear end of the base member. A suitable operating lever is connected to one end of the pinion to actuate the same. By swinging the lever forwardly after the movable mold section 3 has been moved away from the fixed section, the plungers 14 are caused to move in the same direction and eject the castings from the mold. In case there be the same number of plungers desired as rack bars, the plungers themselves may be formed with rack teeth in them to be directly engaged by a pinion and thus do away with the connecting bar or plate 15.

In the mold herein disclosed by way of example, the movable section 3 is the one shown with a fiat face as a matter of convenience, whereas it is obvious that either of the mold sections may be movable but preferably the one is stationary which will retain the casting until it is ejected by the ejector mechanism herein described.

An important feature of the invention is the chilling of certain portions of the mold. While this may be accomplished in various ways, circulation of any suitable fluid, but preferably a liquid such as water or oil, through the portions of the mold which are to be chilled has been found to'give excellent results. By such chilling the rate of cooling of the metal of the thick'parts of the cast ing is increased to such an extent that the freezing of such thick parts may be made to occur sooner than the freeing of the thinner metal parts between such thick parts and the gate. By the use of such chilling the metal in the thick parts of the casting or in those parts having sudden variations in cross-sectional dimensions is cooled so as to prevent cracking during freezing.

The fixed section of the mold is provided beneath the casting recesses 5 with a series of passages 20 extending lengthwise thereof, the core 8 has a passage 21 adjacent its bot tom extending lengthwise thereof, and the plungers 14 are hollow, and have axially disposed inlet pipes 22 extending from the rear end thereof to the front end or face engaging the casting. An outlet nipple 23 is located adjacent the rear end. Liquid is circulated through the fixed mold section, core and ejectors by `means of feed and discharge pipes 24 and 25 on opposite sides of the machine. The feed pipe 24 has a connection 26 atits upper end from which short pipe sections 27 extend to the passages 2O in the base portion of the fixed section. A flexible conduit 28 connects one end of the connection 26 with the passage 21 in the core 8, and a branch conduit 29 extends rearwardly and across the rear end of the machine. Branch pipes 30 with valves 30a therein for regulating the flow are in line with each of the ejector plungers 14, extending from the pipe 29 to a point over the rear ends of the plungers 14 and are connected to the inlet pipes 22 of the plungers by means of flexible hose sections 31. v The discharge pipe 25 is connected at its upper end with a connection 32 similar to the connection 26, from which short pipe sections 33 extend to the outlet ends of the passages 20 in the base of the xed mold section 2. A fiexible hose section 3 connects one end of the connection 32 with the outlet end of the passage 21 in the core 8, and a exible conduit 35-'extends rearwardly from the opposite end of the connection 32 and connects vwith a cross pipe 36, connected to the discharge nipples 23 of the plungers 14.

By means of the liquid circulating system above described the parts of the mold adj acent the lower portions of the casting cavities 5 are chilled so that metal in the casting cavities is frozen progressively toward the gate and before the metal freezes in the gates 7. The gates are of relatively smaller cross-sectional area than in molds heretofore used, so that the flow of metal continues while a relatively larger portion of the casting is cooled or frozen, and so that the metal does not freeze in the gates 7 until after all the metal necessary to replace the crystallization shrinkage of the casting is fed to the mold cavity.

In addition to being of relatively smaller cross-sectional area, the gate has a large periphery with respect to its cross-sectional area, that is instead of being circular or elliptical, as is common practice, I have found that it is beneficial to form the gate of a cross-sectional shape such that all parts of the gate are relatively narrow and that there are no Wide or heavy sections of metal in the gate. I have found that for this purpose a gate of T-shape is advantageous. With a gate of such shape the tendency to form pipes extendin down into the casting is prevented and it is not necessary to extend the gate upwardly a considerable distance to provide a large sprue cavity to furnish suiiicient head to prevent the iping formed upon solidification from exten ing down into the casting. Moreover, with a gate of T or similar cross-sectional shape, namely, a gat( having a relatively long and narrow cross-sectional portion and having a laterally extending cross-sectional portlon communicating with said long and narrow portion, depressions in the surface of the casting may in many cases be substantially eliminated, as previously mentioned, such advantageous result being probably due in part to escape of air from within the mold being more readily facilitated by gates of such shape, as the flow of part of the molten metal is directed away from the parting line of the mold.

It will be understood furthermore that my improved gate construction permits feeding of molten metal therethrough for a longer time than is obtainable from a gate having merely a long and narrow portion.

Thus, in the gate illustrated at 7, the metal of the mold bordering both the relatively long and narrow gate portion and the lateral gate. As a result, the vcasting metal disposed adjacent theintersection of the gate portions remains molten longer than the remainder of the casting metal in the gate, thereby increasing the time of feeding of molten metal through the gate to the casting cavity adjacent said intersection.

Heretofore it has usually been considered necessary to apply heat to portions of the mold to prevent freezing in the gate, or to use metallic inserts of high heat conductivity f to chill the thicker parts of the casting. The heating of the mold is expensive and I have found that it is not necessary and in fact slows down the cast-ing operation. It is advantageous to avoid the use of such metallic inserts because they are not so eiiicient for chilling the mold .and because, without such inserts, the mold surfaces can be made of the same metal, or metal having substantially the same properties, Isuch as heat 'conductivity, so that the casting will not contact with metals of varying properties.

The present invention greatly increases the speed of operation by keeping down the temperature of the mold, thus producin a castmg of better physical characteristics.` In view of the greater rapidity of operation, and also in view of the shape of the gate, the sprue cavity can be relatively small and the lsprue metal required is much less than heretofore, when the volume of metal in the sprue was about one half the volume of metal in the cast-ing, which was considered good general practice. By the present method the volume of metal in the sprue need not be more than a maximum of approximately 25% of the volume of metal in the casting, which effects a considerable saving in melting costs.

The cooling of the ejector plunger causes the metal of the castings to be chilled at the points Where, they are en aged by the plungers, so that the relative y hot castings are not deformed by the pressure exerted -thereon by the plungers.

It will be seen that any number of castings may be made in one mold, each casting cavity having a gate connecting it to the common sprue. Furthermore by having the molds designed so that the gates come on the ends of the casting, a series of castings may be easily trimmed simultaneously by sliding lan them on their flat faces on thetable of the trimming machine. Also as the metal coming from the gate is thin in cross-sectional shape it is more easily and quickly cut through than when a circular or elliptical gate is used.

In the modified construction shown in Fig. 5 the base 1a and fixed and movable sections 2a and 3a are constructed in substantially the same manner as the corresponding parts in the modification first described. In this modification, however, the movable section Se has core pins 40 slidably mountedl in openings therethrough and projecting into the casting recesses. The core pins 40 are for the purpose of forming apertures such as bolt holes or the like in desired portions of the casting. The pins 40 are fixed to a plate 41 which is adapted to'bear against the outer face of the movable mold section 3a. A bracket 42 is attached to the base of the movable section and has stop pins 43 detachably secured thereto and projecting toward the plate 41. A screw 9a similar to the screw 9 above described is pivotally attached to the plate 41. The sections 2 and 3a are held in position after they are in close contact by suitable catches 44 pivoted to one of them. When the screw 9a is pulled rearwardly after catches 44 are unlocked, the core pins 40 are iirst partiallywithdrawn lfrom the casting and then when the plate 41 strikes the stop pins 43, the movable section 3a is pulled bodily away from the fixed section 2a.

A suitable recess 50 may be formed in the movable section 3 of the mold adjacent the base, which will prevent small pieces or scraps of metal which fall between the sections of the mold from keeping the mold sections out of close contact.

It will thus be seen that I have provided a mold for casting aluminum alloys and the like whereby the freezing of irregularly shaped castings may be caused to take place progressively toward the gate.

It will moreover be noted that I have rovided a mold having improved liquid coo ing means, whereby the casting metal may be caused to freeze progressively in the desired manner and at a desired rate.

By my improved mold, moreover, the freezing of the casting metal may take place relatively rapidly. Thus the time required for each casting operation is materially rcduced and the production of castings greatly increased.

Furthermore, by reason of the progressive and relatively rapid freezing of a casting as accomplished in my improved mold, less molten metal to compensate for crystal- .lization shrinkage of the casting metal remains to be fed from the sprue cavity through the gate to the casting cavity after the filling of the casting cavity, and hence a smaller sprue cavity may be employed with attendant advantages, including decreased cost of production.

Furthermore, it is to be understood that the particular forms of apparatus shown and described, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modiications of said apparatus and procedure can be made without departing from my invention as defined in the appended claims.

What I claim is:

1. A mold of metal of substantially uniform heat conductivity formed with a casting cavity and a sprue cavity of relatively small capacity compared with said casting cavity, said sprue cavity communieating with the casting cavity through a gate opening of relatively small cross-sectional area, said mold having cooling means adjacent the portions of the casting cavity engaging relatively heavy sections of metal.

2. A mold of metal of substantially 'uniform heat conductivity formed with a sprue cavity, a mold cavity and a gate of relatively small cross-sectional area therebetween, and means for cooling the mold adjacent the portions of the mold cavity engaging thick portions of the casting.

3. A mold comprising` relatively movable sections formed with a casting cavity and a gate, means for clamping said sections together and for shiftin one section with respect to the other, an by one of said sections, said ejector being liquid cooled.

4. A permanent mold for casting bodies of low fusing point and high crystallization shrinkage, said mold having its walls cooled by a circulation of liquid in portions remote from the gate.

5. A permanent mold for casting bodies of relatively low fusing point and relatively high crystallization shrinkage, the walls of vthe mold being formed of met-al of. substantially uniform heat conductivity, and means for cooling desired portions of such walls.

6. A permanent mold for casting irregular bodies of relatively low fusing point and relatively high crystallization shrinkage, the walls of the mold being formed of metal having substantially the same properties, and means for cooling the mold by circulat' ing a liquid through the parts of the mold adjacent the heavier sections of the body being cast disposed more remote from the gate.

7. A permanent mold formed with a mold cavity and a feeding cavity of relatively small capacity compared with the casting cavity, said feeding cavity communicating with the mold cavity -through a gate opening of relatively small cross-sectional area, said mold being waiter cooled labout the cavity at points removed from said feeding opening.

an ejector carried 8. A mold comprising a fixed section and a movable section formed to provide a casting cavity and a gate, said fixed section forming a side and the bottom of the mold, a core carried by the movable section, means for circulating a cooling liquid through the core and through the bottom of the mold and means for shifting said movable section and for clamping said movable section to the fixed section.

9. A mold comprising a base member, a mold section fixed to the base member and having in a side face thereof, recesses forming the casting cavity and gate, a mold section slidably mounted on said base member, and having a flat face adapted to be clamped against the recessed face of the stationary section, a core carried by the movable section adapted to enter the casting recess, means for moving said slidable section on said base member and for clamping said'` slidable section against said stationary section, and means for'circulating a cooling fluid through the fixed mold section and said core.

10. A mold comprising a base. member, a mold section fixed to the base member and having recesses in one side face thereof, forming the casting cavity and gate of the mold, a mold section slidably mounted upon said base member and having a fiat face adapted to fit against the recessed face of the fixed section, means for shifting said movable section toward and from the fixed section and for clamping the movable section to the fixed section, an ejector carried by the fixed section, `said ejector having a face forming part of a wall of the casting cavity, said ejector being water cooled and means for operating said ejector. Y

11. A mold comprising a base member, a fixed mold section and a movable mold section mounted on said base member, a guideway on the base member for said movable section, an actuating screw pivoted to said movable section, a nut on the outer end of the screw having a handle and a peripheral bearin groove and an open topped bearing yoke xed to the base member adapted to receive the groove of the nut and to form a thrust bearing for the screw to enable the movable section to be clamped against the fixed section.

12. A mold comprising a base member, a fixed mold section thereon, having a recess in one side face thereof forming the casting cavit a movable mold section on said base mem er adapted to be moved toward and from the recessed face of the fixed mold section, and to be clamped thereto, a core pin slidably mounted in said movable section and adapted to enter the casting cavity, a retracting member attached to said core pin, a sto carried by said movable section engagea le with said core pin when it is partially retracted, whereby after the core pin is partially retracted further movement of the retracting member will move the movable mold section `away from the fixed section.

13. Arnold comprising a fixed'section having a fiat face formed with a recess forming a casting cavity and a sprue cavity and a` gate T-shaped in cross-section joining the sprue and casting cavities, and a movable mold section having a flat face adapted to be clamped against the recessed face of said fixed section.

14. A permanent mold for Casting an alloy of relatively high crystallization shrinkage and a relatively low melting point, which comprises mold walls forming a mold cavity and a sprue cavity with a T-shape gate therebetween.

15. A permanent mold for casting an alloy of relatively high crystallization shinkage and a relativel low melting point, which comprises mol walls forming a mold cavity and a sprue cavity with a T-shape gate'therebetween, and means for cooling the mold adjacent heavier sections of the body to be cast or the parts ofthe mold more remote from the gate.

16. A permanent mold comprising a base member, a movable mold section mounted on said base member, a guideway on the base member for said movable section, an actuating screw pivoted to said movable section, a

nut on the outer end of the screw having j a handle and a peripheral bearing groove, and an open-topped bearing yoke fixed to the base member adapted to receive the groove of the nut and to form a thrust bearing for the screw to enable said movable section to be clamped in desired position on said base member.

17. In a permanent mold, a plurality of mold sections, said mold sections defining a casting cavity, a sprue cavity, and a gate 1ntermediate and connecting sai-d sprue and casting cavities, said gate having a relatively long and narrow cross-sectional portion and a laterally extending cross-sectional portion communicating with said relatively long and narrow portion.

18. In a permanent mold, a pair of mold sections, one of said mold sections being recessed to form a caster cavity, a sprue cavity, and a gate intermediate and joining said sprue and casting cavities, the other mold section having a flat face and bein adapted to cooperate with said recessed mo d section, said gate having a relatively long and narrow cross-sectional portion and a laterally extending cross-sectional portion communieating with said relatively long and narrow portion.

In testimony whereof, I hereunto afiix my signature.

CONRADy VAUGHAN.

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