US2266723A - Method of and apparatus for molding - Google Patents

Description

Dec. 16, 1941. E. G. FAHLMAN METHOD OF AND APPARATUS FOR MOLDING 4 Sheets-Sheet 1 Filed Feb. 26, 1941 n a 2 h l m w m w 4 .mov a wm w Z 4 W I N r A v 5 4 6 6 mm Dec 16, 1941. E. G. FAHLMAN METHOD OF AND APPARATUS FOR MOLDING Filed Feb. 26, 1941 4 Sheets-Sheet 2 INVENTOR Everett G.Fahlmuu BY @W 7 ATTORNEYS Dec. 16, 1941. E, a FAHLMAN 2,26,723

METHOD OF AND APPARATUS FOR MOLDING r Filed Feb. 26, 1941 4 Sheets-Sheet 3 INVENTOR 9" 7 Everett Ga Fail/5mm ATTORN EYS ec. 16, 1941. E. G. FAHLMAN 2,265,723

METHOD OF AND APPARATUS FOR MOLDING Filed Feb 26, 1941 4 Sheets-Sheet 4 m 1 45 I I I g I 8 /z I I I :g

I I i I, i I 46 iNVENTOR Everett G. Fa hlma/n ATTORN EYS Patented Dec. 16, 1941 METHOD OF AND APPARATUS FOR LDING Everett G. F'ahlman, Lakewood, Ohio, assignor to The Permold Company, Cleveland, Ohio, a corporation of Ohio Application February 26, 1941, Serial No. 380,692

7 Claims.

This invention relates to the art of permanent mold casting of light metal such as aluminum and its alloys, and has particular reference to the permanent mold castings of relatively thin walled trumpet shaped articles of aluminum alloy, such, for example, as washing machine agitators.

Considerable clifliculty has been experienced in the casting of trumpet shaped washing machine agitators or dollies. These articles, having enlarged flaring bell ends of thin section which taper to a much smaller stem usually of heavier section, were found to be unsatisfactory when cast in sand because of porosity and similar flaws, leading to the deterioration when subjected to the chemical action of Washing compounds. Numerous designs for permanent molds to cast washing machine agitators have been developed, the different inventors placing the casting cavity in various positions, Attempts have been made to cast this type of agitator with its normally vertical or longitudinal axis in a horizontal position, and also with such axis in a vertical position. Some inventors have positioned the casting cavity so that the small or stem end of the agitator is lowermost, while others have positioned the large end or bell lowermost, the agitator thus being cast in its normal upright position. For example, see the agitator molds disclosed in my prior Patent No. 1,770,368, issued July 8, 1930, which is exemplary of molds which cast the agitator in upright position.

One of the chief difliculties of casting aluminum alloy articles in trumpet shape, especially where wings must be provided as in the case of agitators, is the high crystallization shrinkage of the metal, which is apt to cause voids, sinks and porosity. This characteristic of the metal is aggravated by the requirement of thin sectioned walls in washing machine agitators in order to reduce their weight and cost. Unless the mold is properly designed to introduce the molten metal into the casting cavity with a uniform and even flow and without causing hot spots in the mold, defective castings are apt to result due to the entrapment of air, or porosity and sinks due to the hot spots, or all of these defects may be present in a single casting. While successful castings can be made on molds of the general character shown in my patent referred to above, there are certain types of agitators which require the use of extra sprues and risers so that there is considerable scrap metal on each casting. This metal must, of course, be remelted and reheated, resulting in additional handling and increasing costs. Furthermore, several men may be required to operate and pour a mold which uses a large number of feeding sprues because of the increased quantity of metal required.

It is, therefore, the principal object of the present invention to provide a generally improved permanent mold and method of casting in which the amount of scrap metal on each casting is reduced to a minimum and which may, if desired, be easily and efiiciently operated and performed by one man, and which will produce improved alloy castings of fine grain structure, sound throughout, and free from porosity, voids, and other defects.

Another object is to provide an improved casting method, and a permanent mold for performing the same, in which molten metal enters the casting cavity from the bottom over a relatively small cross sectional area and flows thence upwardly over a progressively increasing cross sectional area, after which the mold is turned to a freezing position in which the portion of the casting cavity containing thelast metal to enter the same is uppermost and is maintained in communication with a supply of molten metal to draw from the same for compensation of crystallization shrinkage of the metal in the casting cavity during freezing. In this respect the present invention incorporates and carries forward certain structural features and process steps disclosed in my copending patent application Serial No. 247,872, filed December 27, 1938, now Patent 2,233,405, dated March 4, 1941.

Another object is to provide a permanent mold of the rotatable or tilting type for casting trumpet shaped articles having wings wherein means is provided for heating the mold adjacent the wings to maintain the same at the proper casting temperature to avoid premature and improper freezing of the wings. Other objects and advantages will become apparent from the following detailed description of suitable embodiments of the invention made in connection with the accompanying drawings, in which:

Figure 1- is a front elevational view, partly in section and with parts broken away, of a permanent mold for casting thin walled washing machine agitators.

Fig. 2 is a fragmentary detail, in section, showing the latch mechanism for locking the mold in pouring and freezing positions, taken substantially on the line 22 of Fig. 1;

Fig. 3 is a vertical section through the center of the mold, with parts removed. taken substantially on the line 33 of Fig. 1;

Fig. 4 is a sectional detail through the stem portion of the mold, taken substantially on the line 4--4 of Fi 3;

' Fig. 5 is a fragmentary detail, in section, illus-- trating the position of the inverted mold parts with relation to the molten metal during the freezing operation;

Fig. 6 is a plan view of the mold in pouring position;-

Fig. '7 is a plan view of the mold in freezing position;

Fig-8 is a perspective view of a rough casting of a washing machine agitator as produced by the mold illustrated in the preceding figures;

Fig. 9 is a vertical, sectional view, with parts removed, corresponding to Fig. 3, illustrating a modification of the invention in which the entire mass of. metal for the casting enters through the neck portion. and the circumferential riser or overflow chamber is eliminated; and

Fig. 10 is a perspective view showing a rough parts from dropping by gravity through the base ring 6 when the mold is rotated to freezing position, as will be later described, a latch 22 is pivoted on bolt 23 to boss I8 and is movable by means of a handle l4 across the end of the rack I'I. If desired, the end of the latch 22 may be beveled so as to have a wedging action against the end of the rack 11. Thus, the core Il may be locked in position by means of the latch 22 so that the disk I6 is held firmly against the base ring 6 and a definite relation is maintained between the base ring and the core for successive casting operations.

Around the core II are arranged a. plurality of separable mold sections 24, 25 and 26. While in the embodiment illustrated three mold sections have been shown, a greater or lesser number may agitator casting as produced by the modification of the invention illustrated in Fig. 9.

Referring to the drawings by numerals of reference, which indicate like parts throughout the several views, the mold embodying my invention and used in practicing my improved method of casting comprises a body or casing portion I provided with oppositely directed bracket extensions 2, which receive axially aligned trunnions 3.

' These trunnions are rotatably journalnd in the upper ends of pedestals 4 which are supported on and may be secured to the floor of the foundry in which the mold is to be operated. The body I may be hollow and roughly of cylindrical form having an internal chamber 5 in which is received the cylindrical portion of a ring-shaped base 6, having a radial fiange portion 1 which rests against one end of the body I. Bolts 8 eitend through the body and are threaded into the ring flange I; the heads of these bolts are positioned in side openings 9 of the body which open into the chamber 5.

The base ring or member 6 is formed with a cylindrical, axially extending bore or opening I!) which slidingly receives a piston-like core member H. This core defines the internal wall or surface of the casting cavity and is formed at its bottom end with a tapering face portion l2 which merges into a central, axially extending stem portion l5, circular in cross section. In the pouring position of the mold illustrated in Fig. 3, the stem portion l5 of the core H is directed downwardly and the core is retained in predetermined fixed position relative to the base ring 8 by means of a disc member or gauge I5 secured 1 to the end of the core ll opposite the stem I5, and movable therewith into abutting relation with one end of the base ring 6. The core II is thus prevented from sliding through the base ring when the mold is placed in pouring position by the engagement between the edge portions of the disk I6 and the base ring 6.

An axially extending rack bar I! is secured into the center of the disk l6 and is guided for endwise sliding movement in a passage formed in an extension boss l8 of the body I. A pinion l9,

also journaled in the boss l8, engages the rack l1 so that the latter may be thereby shifted longitudinally in the boss to advance and retract the core II in the base ring 5. The pinion I9 may be secured on a shaft 20 which extends transverselv' through. the boss l8 and has secured thereto ahandle 2| for manually rotating the same and thereby actuating the pinion I9.

In order to prevent the core II and associated be used, if desired, or if required in designing a mold to cast a different type of agitator or similar article from that shown. The mold sections enclose the core ll, including the stem I5 thereof, and are shaped to cooperatively define therewith the casting cavity of the mold. In -Fig. 3, the casting cavity is shown filled with cast metal.

Suitable means is provided for moving the mold sections 24, 25 and 26 toward and away from one another so that the mold may be opened and closed. If desired, the mold sections may each be formed with extensions 28 which are pivoted on short shafts 29 carried by ears 30 formed on the body or casing I. Handles 3| may be secured to the mold sections to facilitate the manipulation of the latter in opening and closing the mold.

As illustrated in Fig. 1, the mold sections converge and the ends thereof, remote from the body or casing I of the mold, are embraced by a clamp 34 which has a pressure block 35 actuable by a threaded rod 36. This clamp draws the meetin faces of mold sections tightly together so that the casting cavityis accurately defined and of predetermined size and shape for each of the successive casting operations and insures that the mold sections are equally spaced around the stem l5 of the core. As shown in Fig. 3, the clamp 34 embraces a cylindrical neck 31 formed by the ends of the several mold sections and abuts against a shoulder 38.

Meeting faces 39 of the mold sections 24, 25 and 26 are recessed to cooperatively define wing casting portions of the casting cavity in which wings 40 of the agitator are formed. These wings extend radially from the stem 21 of the agitator and are integral therewith.

One or more pairs of the meeting faces of the mold sections, for example, the meeting faces of the sections 24 and 25, are extended beyond the body I of the mold and are recessed or cooperatively formed to define a pouring sprue 4|. This pouring sprue extends from an enlarged inlet portion 42 disposed above the level of the uppermost portion of the casting cavity when the mold is in pouring position, as shown in Fig. 3, downwardly to a point well below the lowermost portion of the casting cavity where the pouring sprue is arranged to feed into bottom portion 43 of a feeding chamber. Upper portion 44 of the feeding chamber receives molten metal directly from the smaller lower portion 43 through a restricted opening 45. This feeding chamber is disposed wholly below the casting cavity and communicates with the latter through an ingate 46 which may be of restricted area, or as shown, may be of substantially the same cross sectional area as the relatively thick section portion 41 of the agitator stem.

In some agitators it is desirable to provide a socket to receive a drive spindle. For this purpose an extension post 48 is threaded into the end of the stem and projects downwardly I therefrom through the end of the casting cavity and into the upper part 44 of the feeding chamber. This post is adapted to receive and support a metal sleeve 49 of brass or bronze which becomes embedded in the casting and provides a wear-resisting socket for the drive spindle on which the agitator is to be mounted.

Along the casting cavity portions defining the wings 40 of the agitator, the meeting faces of the mold sections are cooperatively formed or recessed to define auxiliary distributing sprues 50. These sprues preferably parallel the marginal edges of the wing forming cavity portions, as shown in Fig. 3, and communicate with the wing cavity portions through relatively narrow or thin gates 5| (Fig. 4). The lower ends of the distributing sprues 50 communicate through openings 52 with the upper or large portion 44 of the feeding chamber.

Outwardly'of the agitator base defining portion of the casting cavity, the mold sections have faces which seat against the face of the annular fiange portion 1 of the base ring 6. These, faces which meet along the line indicated at 53, are cooperatively recessed or otherwise formed to define a circumferentially extending riser or overflow chamber 54. This riser extends about the periphery of the base forming portion of the casting cavity and is preferably completely circumferential or annular in extent, although a lesser extent may be used. The casting cavity communicates with the riser or overflow chamber 54 through narrow slots or openings 55.

The mold is mounted on the pedestals 4 by means of the trunnions 3 and is balanced so that it may be easily rotated from the pouring position shown in Fig. 1 by the full lines to the broken line freezing position of that figure. If necessary, counterbalancing weights 56 may be mounted on rods 51 threaded into sockets in the body casing One of the trunnions 3 has a hub 58 secured thereon and this hub isprovided with arms 59 by means of which the movable or shiftable parts may be rotated to move the mold between pouring and freezing positions. In order to lock the mold a latch 60 (Fig. 2) is pivoted at 6| to one of the pedestals 4 and has a bifurcated end 82 which can be moved toward and away from the path of the arms 59. These arms are located about the hub 58 so that when the mold is in pouring and freezing positions an arm is opposite the latch 60 to be embraced by the bifurcated end thereof, as shown by the full lines of Fig. 2. A spring 63 retains the latch in engagement with the arms until the latch is retracted by means of a foot treadle 64 connected to the latch by a cable 65 trained over a pulley 66 supported by a bracket formed on the pedestal 4.

In operating a mold of the character described in accordance with my improved method, the mold is first brought to operating temperature in the usual manner, as by gas flames and preliminary pouring and is then assembled with the mold sections disposed about the core II and held together by means of the clamp 34, the core being locked in place by means of the latch 22. The mold is placed in pouring position,

illustrated by full lines of Fig. 1, and the latch 60 is placed in engagement with one of the arms 59 to lock the mold in pouring position. An operator then pours the molten metal from a ladle into the mouth 42 of the pouring sprue 4| which, as shown in Fig. 3, slopes inwardly toward the longitudinal axis of the casting cavity. From the pouring sprue the molten metal flows into the bottommost or smaller portion 43 of the feeding chamber and thence throughthe restricted opening 45 and into the larger portion 44 of the feeding chamber. Since the bottom portion 43 of the feeding chamber is filled with molten metal, the latter rises uniformly and evenly, upwardly through the large portion 44 of the feeding chamber and thence around the sleeve 49 and through the ingate 46to the casting cavity defined by the mold section-s and the core As the molten metal rises in the casting cavity, it pushes the air out'through the upper portions of the mold through vents, not shown. Furthermore, foreign material is carried along by the advancing metal so that the surfaces of the molds are swept clean. when the mold cavity is completely filled, the first metal to enter the mold is forced through the slots 55 and into the circumferential riser or risers 54, carrying with it any foreign material that may have accumulated and air that may have become trapped in the metal first entering the mold.

The relatively large volume of metal in the chamber 44 and the portion 41 of the stem as well as the large cross sectional area of these parts of the mold tends to quiet the fiow of the metal and decrease the turbulence thereof.

Simultaneously with the flow of metal into the casting cavity through the ingate 46, metal rises in the auxiliary distributing sprues 50, and when the level therein rises above the bottoms of the gates 5| the molten metal flows from the sprues 50 through the gates 5| and into the wing forming portions of the casting. In this manner, a portion of the molten metal instead of being forced to flow through the portion of the cavity which defines the stem of the agitator is carried directly by the auxiliary sprues 50 to the marginal edges of the wings 40 where the metal enters the casting cavity closer to its ultimate location than if all the metal were introduced through the ingate 46.

In addition to supplying molten metal to the wings of the casting, the auxiliary sprues 50 retain molten metal which heats the adjacent portions of the mold sections to maintain the same at the proper operating temperature. For this purpose the cross sectional area of the auxiliary sprues 50 may be varied as desired so that the heat capacity of the metal contained therein will be sufficient when imparted to the mold sections to keep the latter at a sufiiciently high temperature to prevent premature freezing of the metal forming the wings 40 of the agitator. Customarily, molds are operated continuously for a period of several hours, during which time the mold is refilled with molten metal as soon as a solidified casting has been removed therefrom and the necessary attention given to preparing the mold for the next casting. It is, therefore, extremely important that all portions of the mold be maintained at the proper temperature for performing the casting operation with the greatest accuracy and efliciency possible and with a minimum number of defective castings. Because of the relatively thin character of the metal forming the base portion l2 and stem portion 21 of the agiator, it is important to avoid excessive cooling of one portion of the mold as well as excessive overheating of other portions. By the use of the auxiliary sprues 50, hot molten metal can be carried directly to the relatively remote portions of the casting cavity to prevent premature freezing of the metal therein and to prevent the mold por tions adjacent such remote portions of the casting cavity from falling to an undesirably low temperature through loss of heat to the atmosphere.

As previously indicated, molten metal from the casting cavity flows into the circumferentially extending riser 54 through the passages 55 when the mold is substantially filled. By this arrangement foreign material and entrapped air can be carried out of the casting cavity into the riser 54 and the metal remaining in the casting cavity tends to be of a more uniform temperature. Additionally, the molten metal forced into the riser 54 serves to heat the portions of the mold surrounding the base of the casting cavity to maintain the same at the correct casting temperature. If desired, the cross sectional area of the riser or risers 54 may be increased or decreased as the necessity for supplying more or less heat to the base portions of the casting becomes apparent.

When the operator observes the molten metal rising in the mouth 42 of the pouring sprue, he stops pouring metal into the mold since the appearance of the metal in the upper end of the pouring sprue indicates to him that the metal within the casting cavity is substantially at the same level and that the casing cavity is therefore completely filled. The arm 59 held by the latch 60 is then released and the filled moldrotated on the trunnions 3.0 from the full line pouring position illustrated in Fig. .1 to the freezing position illustrated by the broken lines of the same figure. The mold is then looked in freezing position through engagement of one of the arms 59 by the latch 60. As the mold rotates from pouring to freezing position in a counterclockwise direction as viewed in Fig. 3, the molten metal inof molten metal since the inertia of the'metal' resists the flow for the short period of time during which the sprue 4| is so positioned as to permit the metal in the casting cavity to flow out of the mold therethrough. If, however, the mold is rotated clockwise,.as viewed in Fig. 3, there will be no objectionable loss of metal from the feeding chamber or casting cavity.

When the mold is locked in freezing position, molten metal indicated at 69 (Fig. 5) is trapped in the feeding chamber, filling the large portion 44 thereof and also the small portion 43 thereof up to the level of the opening into the pouring sprue 4|. The connection of the pouring sprue 4| toa portion of the feeding chamber whichis spaced well beyond the end of the stem forming part of the casting cavity entraps a consider- When so rotated the' able volume of metal in the feeding chamber troduced into the mold. Accordingly, it is the hottest metal in the mold since all the metal previously introduced into the mold flowed-over the walls of the casting cavity and sprues and was cooled thereby. The coldest metal in the casting cavity when the pouring operation is completed is that which is in the base forming portion [2 of the cavity and adjacent the circumferential riser or risers 54.

During the freezing of the metal in the casting cavity the coldest metal in the base or bell forming portions l2 tends to freeze first, followed by that in the wings 40. The portions of the casting to freeze first, after turning of the mold to freezing position, will be determined by the particular design of agitator being cast and the volumetric capacities of the auxiliary sprues 50 and circumferential riser or risers 54. Both the bell shaped or base portion l2 of the casting and the wings 40 freeze prior to the freezing of the metal in the elongated stem portion 21 of the agitator. Accordingly, crystallization shrinkage in the bell and wing portions of the casting cavity is compensated for by molten metal from the stem portion 21, which in turn draws upon'the body 69 of molten metal remaining in the feeding chamber at the tip and of the stem 21. As indicated above, the metal 69 in the feeding chamber being the last to enter of the metal in the mold, is at the most elevated temperature and therefore remains in a liquid condition until after thefreezing of the metal in the casting cavity. Thus, 'there is maintained above the casting cavity an available body of liquid metal which feeds the casting cavity during solidification to compensate for the shrinkage of the aluminum alloy used in making the castings.

After the casting has solidified the clamp 34 i is removed and the mold sections 24, 25 and 26 separated from one anotherand the casting. The core may be released by the latch 22 and .retracted by actuation of the lever 2| either before or after the separation of the mold sections. The rough casting is removed from the mold and has approximately the appearance shown in Fig. 8. This casting is then trimmed in the usual manner, the sprues 4| and circumferential risers 54 being remelted, if desired, and added to the body of molten metal from which the castings are made. In this connection it is to be observed that a relatively small quantity of metal is utilized in the risers and sprues and there is therefore a relatively small amount of scrap metal which must be. remelted and reclaimed. The metal 69 which solidified in the feeding chamber is severed from the top of the casting adjacent the ingate 46, this operation also cutting off a portion of the brass or bronze sleeve 49.

- In Fig. 9 is illustrated a modification of the invention in which the mold is constructed substantially the sameas that illustrated in the previous figures, the corresponding parts being indicated' by the same numerals of reference as those previously referred to. In this modification, however, the circumferential riser or rlsers 54 have been omitted and also the auxiliary dstributing sprues so that all of the metal flowing into the casting cavity passes through the ingate 46 and there is no washing of the metal through the casting cavity into the risers. The inflowing metal rises progressively through the stem portion 21 of the agitator and flows thence laterally into the wings 4|! and during the final stages of the pouring operation the metal flows into the base or bell portion l2 of the agitator.

As in the embodiment first described, the metal first entering the mold is carried upwardly to form the base portion l2 of the casting, and the metal 69 enters thebottom of the feeding chamber from the outlet of the pouring sprue 4|. It is thus appparent that the metal ultimately forming the base or bell portion of the casting is first passed over a large surface area of the casting cavity walls so that its temperature is materally reduced by the time it reaches the peripheral margin of the agitator bell. There is, accordingly, a progressive increase in temperature of the metal from the peripheral portions of the agitator bell centrally and then along the stem 21 to the metal 69 in the feeding chamber. When the mold is rotated or shifted to inverted freezing position the metal 69 remaining in the feeding chamber is the hottest metal in the mold and constitutes a source of supply from which molten metal is fed downwardly into the stem of the casting to compensate for crystallization shrinkage. The solidification of the casting is progressive from the edge of the bell l2 toward the stem 21 and thence upwardly along the-stem tothe feeding chamber.

Upon solidification of the casting made in the mold of Fig. 9, the mold is opened in the manner previously described and the rough casting illustrated in Fig. 10 is removed and trimmed. In this casting there are no .sprues or risers to be trimmed ofi and the scrap metal to be reclaimed is restricted to a relatively small mass 69, which is the residue of the feed supply in the feeding chamber. I

By the present invention there is provided an improved casting apparatus and method which produces improved thin walled hollow articles with less labor and material than formerly and which minimizes the number of castings that are defective because of porosity, occluded air, and other defects well known in the casting art which result from cold shuts or hot spots in the mold. The mold of the present invention may be operated by a single man if desired and the amount of scrap loss is materially diminished so that the expense of operation is substantially reduced. The pouring of the molten metal into the mold so that the metal enters solely'from the bottom of the casing cavity insures the positive ejection or displacement of air from the casting cavity ahead of the incoming metal, and that the likelihood of air entrapment is practically eliminated. Furthermore, this introduction of all of the molten metal into the casting cavity from the bottom thereof distributes the metal in such a way that when the casting cavity is filled, the hot metal is at one end thereof and the cold metal is at the other end thereof. The subsequent turning or shifting of the completely filled mold from a pouring position in which the hottest metal is at the bottom to the freezing position in which the hottest metal is at the top, enables the molten metal to feeddownwardly into the casting cavity for the purpose of compensating for recrystallization shrinkage which occurs during the solidification of the casting. The invention also provides a unique feeding chamber of flow'quieting volumetric capacity which contains the hottest metal in the filled mold which is available and is disposed above the level of all of the other metal in the mold so as to feed downwardly during solidification and thereby produce a sound casting which is free from draws and skins.'

The principles of the present invention may be utilized in various ways, numerous modifications and alterations being contemplated, substitution of parts and changes in construction being resorted toas desired, it being understood that th embodiments shown in the drawings and described above are given merely for purposes of explanation and illustration without intending to limit the scope of the claims to the specific details disclosed.

What I claim is:

1. A permanent mold for casting trumpet shaped articles having projecting wings, comprising a core and mold sections cooperatively formed to define a casting cavity having stem and bell portions and mounted to rotate as a unit about a substantiallyhorizohtal axis between a pouring position in which the stem portion is at the bottom and a freezing position in which the stem portion is at the top, said mold sections having meeting faces cooperatively recessed to define wingcavity portions, a feeding chamber formed in the mold sections and disposed below said stem portion of the cavity when the mold is in pouring position, said meeting faces also formed to define feeding sprues extending along the edges of the wing'portions and communicating with said chamber, means for conducting niiilten metal under pressure into said chamber, means for turning the mold from pouring position to freezing position, and gates between the chamber and sprues and the casting cavity through which molten metal is forced to flow during the casting operation from said chamber into the sprues and the stem portion of the cavity and thence into the bell portion of the cavity, and through which molten metal feeds downwardly into the cavity during freezing of the casting to compensate for crystallization shrinkage of the metal.

2. A permanent mold for casting trumpet shaped articles comprising a core and mold sections cooperatively formed to define a casting cavity having stem and bell portions mounted to rotate as a unit about a substantially horiontal axis between a pouring position in which the stem portion is at the bottom and a freezing position in which the stem portion is at the top, said sections having meeting faces cooperatively formed to define a feeding chamber disposed below said stem portion when the mold is in pouring position, said meeting faces being additionally recessed to cooperatively define at least one pouring sprue communicating with the chamber well below the casting cavity when the mold is in pouring position and extending from the chamber upwardly above the level of the bell portion of the cavity, means for turning the mold from pouring position to freezing position, and a gate between the chamber and the cavity through which molten metal is forced to flow during the casting operation from said chamber into the stem portion of the cavity and thence into the bell portion thereof and through which molten metal, trapped in the chamber upon movement of the mold to freezing position, feeds downwardly into the casting cavity to compensate for crystalliaztion shrinkage of the metal.

3. A permanent mold for casting trumpet shaped articles comprising a core and mold sections cooperatively formed to define. a casting cavity having stem and bell portions, and mounted to rotate as a unit about a substantially horizontal axis between a pouring position in which the stem portion is at the bottom and a freezing position in which the stem portion is at the top, a feeding chamber formed in the mold sections and disposed below said stem portion of the casting cavity when the mold is in pouring position, means for conducting molten metal under pressur into said chamber, means for turning the mold from pouring position to freezing position, and a gate between the chamber and the casting cavity. through which molten metal is forced to flow during the casting operation from said chamber into the stem portion of the cavity and thence into the bell portion thereof, and through which molten metal feeds downwardly into said stern portion during freezing of the casting to compensate for crystallization shrinkage of the metal in the cavity.

4. A permanent mold for casting integral thin sectioned trumpet shaped articles such as washing machine agitators having bells and stems all of high crystallizationf shrinkage metal, comprising a supporting structure, a base mounted on the structure-for rotation about a substantially horizontal axis, a movablecore and mold sections carried by the base for rotation therewith and fitting together to cooperatively define a casting cavity having a bell forming portion normally disposed uppermost and a stem forming portion lowermost, a feeding chamber formed in the sections below" the stem portion and communicating with said stem portion whereby molten metal forced into the chamber flows upwardly therethrough, thence upwardly through said'stem portion of the cavity and into the bell portion, means for introducing metal under pressure into the chamber, and means for turning the base, core and mold sections as a unit about said axis from said normal pouring position to an inverted freezing position in which the feeding chamber is above the stem portion, the chamber being formed to trap a body of molten metal therein which flows downwardly into said stem portion of the cavity during solidification of the casting to compensate for crystallization shrinkage. I

5. A permanent mold for casting integral thin sectioned trumpet shaped articles such as washing machine agitators having a bell and a stem all of metal having relatively high crystallization shrinkage, comprising a supporting structure, a base pivotally mounted on the structure for rotation about a substantially horizontal axis, a movable core and a plurality of movable mold sections carried by the base and fitting together to define a casting cavity normally disposed with the bell forming portion uppermost and the stem forming portion lowermost, the abutting edges of adjacent sections being formed to cooperatively provide a feeding chamber below said stem portion and a pouring sprue extending from about the level of the uppermost part of the bell portion to such chamber whereby molten metal introduced into the sprue flows downwardly therein, thence upwardly through the feeding chamber and into the stem portion of the cavity to fill the same first and then flows to fill the bell portion of the cavity, and means for turning the base with the core and mold sections about said axis from said normal pouring position, to an inverted freezing position in which the feeding chamber is uppermost, said sprue communicating with the feeding chamher through an opening which is well below the end of the stem portion of the cavity when the mold is in pouring position so that the metal last introduced into said chamber during the pouring operation is trapped therein upon inversion of the mold to freezing position to feed downwardly into said stem portion during freezing of the metal and to compensate for crystallization shrinkage.

6. A permanent mold for casting trumpet shaped articles comprising a supporting structure, a base part mounted on the structure for rotation about a substantially horizontal axis, a core part and mold parts carried by the base and arranged to rotate therewith as a unit, said parts being formed to cooperatively define a casting cavity having stem and bell portions, means for rotating the parts as a unit between a pouring position in which the stem portion is at the bottom and a freezing position in which the stem portion is at the top, saidparts having meeting faces formed to cooperatively define a feeding chamber disposed below the stem portion and a circumferential riser chamber extending around the edge of the bell portion, means for conducting molten metal under pressure into said-feed ing chamber, at least one gate between said feeding chamber and the casting cavity through which molten metal is forced to flow during the casting operation from said feeding chamber upwardly into the stem portion of the cavity and thence upwardly into the bell portion of the cav ity, and through which molten metal feeds downwardly into the casting cavity during freezing of the casting in freezing position to compensate for crystallization shrinkage of the metal, and at least one passage between the bell portion of the cavity and said riser chamber through which molten metal flows from the bell into said riser chamber during the final stages of the casting operation to carry impurities from the cavity and to supply a body of metal from which heat'is withdrawnto maintain the mold at operating temperature.

7. The method of casting integral thin sectioned trumpet shaped articles, such as washing machine agitators having bells and stems, of high crystallization shrinkage metal, in a permanent mold, which comprises positioning the mold withthe stem defining portion of the casting cavity at the bottom, conducting molten metal upwardly into the stem portion of the casting cavity and'thence upwardly into the bell portion of the casting cavity in a continuous operation until the mold is filled, inverting the filled mold to freezing position in which the stem portion of the casting cavity is above the bell portion of the cavity so that the hottest metal is at the top of the casting cavity, and

maintaining a body of molten metal last introduced into the mold above the stem portion of the cavity and in communication therewith during freezing of the casting to feed downwardly into the casting cavity to compensate for crystallization shrinkage of the metal therein during the freezing process.

EVERETI G. FAHiMAN.

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