US2198498A - Apparatus for forming sprue tube sockets - Google Patents

Description

, H. F. HAGEMEYER 2,198,498

APPARATUS FOR FORMING SPRUE TUBE SOCKETS A ril 23, 1940.

Filod im 11, 195a ZSheets-Sheet 1 JNVENTOR. HENRY F. HAGEMEYER ATTORNEY.

April 23, 1940- H. F. HAGEMEYER 2,198,498

APPARATUS FOR FORMING srnua TUBE sqckms v rind a 11, 19:8 2 Sheets-Shet z I HENRY F. HAGEMEYER- WM ATTORNEY.

Patented Apr. 23, 1940 Henry F. Hagemeyer, Chicago, 111., assignor to Castings Patent Illinois Corporation, a corporation of Application June 11, 1938, Serial No. 213,164

- 7 Claims.

My invention pertains to molds and in particular to the provision of a novel sprue therefor and to apparatus for preparing a mold for reception of a sprue of my improved type.

Heretofore it has been general foundry practice to prepare the cope of a mold with a sprue hole therein communicating with the mold cavity. In some instances, especially where the mold is on a slight angle with the sprue hole in the lower end, it has been-the practice to set on the mold a sprue tube in registry with the sprue hole in the cope in order to provide a greater head of metal and to obtain a more even flow of metal into the mold cavity. Such supplemental sprue tubes have been molded separately of the same material of which the mold proper is made, and hence have required an additional molding operation. These supplemental molded sprue tubes have been used both in sand molding and in plastic molding practice.

It has also been proposed to provide permanent supplemental moldsprues for sand and plastic molds sometimes formed as part of an upper weight or pressure plate. The diihculty with suchsprues, however, is that if the supplemental sprue is used to the best advantage, namely, to receive enough metal to keep a substantially constant head while pouring, and after pouring to provide a reservoir of .hot molten metal from which the casting can draw as the metal therein solidifies and shrinks, the metal will extend up into the permanent supplemental sprue. Asa result, it is only with dimculty that the poured metal may be removed from the permanent sprue tube after it -has solidified. A sprue tube made of mold material may, of course, be broken from the metal in the same manner that the material of the mold proper is separated therefrom.

I have devised a way of obtaining the advantages of the supplemental sprue tube of mold material without the relatively high cost of preparing it as a separate mold section. In essence I form a laminated sprue tube of heat resistant sheet material; for example, I roll a sheet of .asbestos spirally into a tube of the thickness of' several sheets, secure the edges of the rolled sheet, and then sever the tube thus fabricated into appropriate lengths for sprue tubes. Such a sprue tube is attached to the cope preferably by setting its lower end into a socket formed about the sprue hole in the cope, either in the form of a cylindrical depression oras an annular groove. Such a socket may be formed during the molding process bypacking the mold material about a cylinder or ring of appropriate size. and

shape which is withdrawn in the same manner that the pattern is separated from the mold, but preferably from the opposite side, and either manually or automatically.

My principal object is, therefore, to provide an easily fabricated attachable supplemental sprue tube which may readily be broken up and discarded but which will be heat resistant and sufficiently durable to serve its purpose.

It is a more specific object to construct such a sprue tube out of thin and relatively inexpensive sheet material, such as asbestos, in the form of a spiral, which can be easily and cheaply formed, yet which will be self-sustaining in that I it will have sufficient hoop tensile strength to withstand the stress exerted by the radially outward pressure of the molten metal as it fills the tube, and sufiicient stiffness to stand upright when supported only by its lower end.

Another object is to attach the sprue tube to the cope of the mold in such a way that a tight joint will be formed and. the lower end of the tube will be prevented from splitting, preferably by seating the lower end of the sprue tube in a socket in the cope surrounding the sprue hole.

Still a further object is to provide apparatus for forming the socket for the sprue tube in the mold with the least difflculty.

It is also an object to provide a mold structure for causing the end of the sprue tube to be clamped in its socket by material forced against the tube by molten metal flowing throughthe sprue aperture of the mold.

An additional object is to provide mechanism for forming the sprue socket accurately in relation to the sprue aperture of the mold, and preferably which will perform such operation automatically without attention on the part of an operator. 1

Further objects will be noted in the subsequent description of the mold and sprue tube structure .and of the tube socket forming apparatus, illustrated in the drawings as exemplifying types of I installations.

Fig. l is a vertical section through a mold and an attached sprue tube.

Fig. 2 is a plan view of a mold with an attached sprue tube in section taken along the line 2-2 of Fig. 1. v

Fig. 3 is a vertical section through another tube.

form of mold structure and an attached sprue Fig. 4 is a vertical section through a mold and a device for forming in a mold the sprue tube socket shown in Fig. 1. i

Fig. 5 is an end elevation view, and

Fig. 6 is a side elevation view, showing parts in section, of a modified form of device for forming in a mold the sprue tube socket shown in Fig. 1.

Fig. 7 is a transverse section taken along the line |-'l of Fig. 6 with the flask and mold omitted.

- Fig. 8 is a plan view of a portion of the device shown in Fig. 6. f

Fig. '9 is a vertical section through a mold showing in elevation a device for forming in a mold the sprue tube socket shown in Fig. 3.

In conventional molding practice the cope of a mold M has been provided with a sprue aperture A extending through the mold body from its upper surface, that is the back of the cope, down into communication with a runner R which feeds the mold cavity. Such aperture and runner may be molded directly into the moldby incorporation in the pattern of a sprue post P and a runner bead B, shown in Figs. 4, 6 and 9. Especially is such a method of forming the runner and sprue aperture useful in plastic molding practice, where the molding material is of the gypsum base type. Where a supplemental sprue tube is used conventionally, it is molded as a. separate mold section and merely set on top of the cope with its bore in registry with the sprue aperture A of the mold.

I have devised a way of eliminating the separate molding operation previously required to make the sprue tube, by fabricating it from heat resistant sheet material, preferably asbestos. Satisfactory stock is flexible sheet asbestos one thirty-second of an inch in thickness. I take such a sheet of asbestos and roll it spirally into a tube with a wall thickness of two or three lay-.

ersor thicknesses of sheet. Of course if thicker material is used a single layer roll, except at the seam, may be sufficient, while if thinner sheet material is used more layers may be required. I have found that a wall thickness of one-sixteenth inch is satisfactory for a sprue tube of one and one-half or two inches in diameter. Preferably, the exterior flap only is stuck to the body, using any satisfactory heat resistant glue. For use on asbestossheet a satisfactory adhesive is waterglass or sodium silicate. The sheet material may be formed into a long tube and then cut transversely into individual lengths appropriate for attachment to the individual molds, varying according to the static head of metal desired for the respective molds.

These individual sprue tubes 1, shown in Figs. 1, 2, and 3, while self-sustaining, are obviously, because of their small wall thickness, which has been greatly exaggerated in the illustration of the drawings for clarity, rather flimsy and should be adequately supported at their lower ends where the pressure of the molten metal flowing therethrough is greatest, to prevent splitting of the tube end. As an effective and simple method of affording support for the lower end III of the sprue tube, I provide in the back of the cope a socket surrounding the sprue aperture A, including a substantially cylindrical wall 20 for engagement with the exterior of the sprue tube end, and an end wall 2| against which the end of the tube abuts and which takes the thrust thereof as the metal is poured into the tube. Such .a

socket may serve as the sole support for such sprue tube.

In the form shown in Figs. 1 and 2, the tube socket takes the form of an annular groove 2 encircling the conventional sprue aperture A. This groove is preferably slightly wider than the wall thickness of the sprue tube and somewhat wider at, the top thanat the bottom adjacent to the end wall or seat 2|. The groove 2 is separated from the sprue aperture A by an annular flange 22, which because of the varying width of the groove 2, becomes thinner toward its edge, and such edge is spaced farther from the inner wall of the attached sprue tube than is the base of such flange.

When the molten metal is poured into the mold cavity through the attached sprue tube l and the sprue aperture A, some of it lodges in the cavity between the annular flange 22 and the interior surface of the attached sprue tube. Be-

cause the flange 22, the sprue tube, and the mold material surrounding the base thereof is cold the first molten metal entering the groove 2 is rapidly chilled and changes to the semi-solid state. The molten metal flowing into the groove thereafter strikes this flrstfsemi-solid, plastic metal and drives it as a wedge into the base of the groove, forcing it to deform and to press the sprue tube outward into tight engagement with the wall 20. Metal subsequently flowing into the groove is similarly wedged in until the groove is completely filled.

The sprue tube socket in the mold of Fig. 3 is not provided with an inner flange as shown in the type of Figs. 1 and 2. Instead, secure seating of the sprue tube is insured by forming the wall 20 with a slight incline so that its circumference will decrease progressively toward the end wall 2|. As the end III of the sprue tube is forced into its seat, therefore, it will be slightly contracted and thereby will be wedged tightly into contact with the wall 20 of the tube socket.

The tube end will be pressed even more tightly against this wall by the inflowing molten metal during pouring of the mold, but even though the wall 20 should yield slightly under pressure of the molten metal the end III 'of the tube will not be ruptured or split because of its having been previously contracted by the seating operation.

The sprue tube sockets may be formed in the molds during themolding process by apparatus such as illustrated in Figs. 4- to 9, inclusive, Figs. 4 to 8, inclusive, pertaining to apparatus for forming the type of socket shown in Figs. 1 and 2,

and Fig. 9 showing apparatus for forming the 55 socket of Fig. 3. In both cases sprue posts P and runner beads B mounted on a match plate are employed for forming the mold sprue apertures and runners, respectively.

The annular groove 2 may be formed by embedding in the back of the cope a ring of a greater diameter than the sprue post in a. position encircling such post, while the mold material is soft and is still contained in a mold form or flask F. Such ring may be'in the form of a cup 3 05 limited in its proper position by abutment of the 70 inner surface of the central portion of the bottom, which may be formed with a boss 32, against the'upper endof the sprue post, as shown. Downward movement of the solid substantially cylindrical sprue forming member 4 of Fig. 9 is 1 cylinder (is also of greater width than the sprue post in order to form the tube end engaging surface ii of Fig. 3 and a substantially cylindrical wall 20 encircling the sprue aperture in the mold for engaging the sprue tube end.

The sprue tube socket forming member should also be positioned approximately concentric with the sprue post. Such member may engage the sprue post-laterally, as shown in Figs. 4 and 9, or its lateral disposition may be controlled by exterior mechanism bearing a definitely calculated relationship to the mold form in which the sprue post is fixed, as shown in Figs. and 6. In the former type it is convenient to provide on the end of the sprue post a reduced shank 5 which seats in a socket provided in the center of the socket forming member. After the mold is formed such member, 3 or 4, may be lifted from embedment in the back of the cope and from engagement with the reduced shank 5 of the sprue post before the match plate, on which such post is mounted, is separated from the mold.

In the alternative construction of Figs. 5 and 6 the cup 3 is engaged from above by a locating mechanism generally indicated at 6 which also serves as a cup support and reciprocating mechanism, to be described in more detail hereafter.

Withdrawal of the socket forming member is facilitated by providing a slight draft thereon. In the .cup type 3 the inner surface of the skirt 30 is formed of slightly frusto-conical shape divergent toward its rim, while its outer surface may be precisely cylindrical. In the solid mem her 4 of Fig. 9 the draft will be on the external surface. In either case slight upward movement of the member will almost instantaneously free from contact with the mold'the entire draft surface and break the vacuum between the socket forming member and the mold material. For access of airto the internal draft surface of cup 3 I provide several holes 33, as in Fig. 4, or slots 33', as in Figs. 6 and 7, in the base'al projecting beyond the surface of the mold, between its central portion or boss and the flange 30.

Since the base SI of cup 3 projects beyond the surface of the mold the cup may be lifted by manually grasping such base. The same procedure may be employed in removing the member 4, shown in Fig. 9, from the mold, or a handle 40 may be provided to assist in such operation. I prefer, however, that the cup be inserted and removed automatically, such as by the mechanism shown in Figs. 5, 6 and 8.

The automatic supporting and actuating mechanism for the socket forming member, generally indicated as 6, includes a mold form or flask supporting table 60 which carries fixed guides Si in which rods 62 are received and guided for vertical reciprocation between a lower position, corresponding to the embedded position of the socket forming member, and an upper position, corresponding to the withdrawn position of the member. An arm 63 carried by the upper end of the reciprocating rods 62 extends laterally therefrom, overhanging a mold form or flask F on table 60, to position a socket forming member supported on the end of the arm 63 in registry with the sprue post of the fiask'smatch plate. Asthe rods 62 are slid up or down the arm supported socket forming member is, of co moved correspondingly.

In operation, the mold material is usually first placed in the mold form and then the socket such material. After the material has. been packed or set the member is withdrawn upward again. 'I'hemechanismfor effecting reciprocation of the rods 62 may be of any suitable tim In order to employ such mechanism in 'a' mold production line, however, I prefer that the whole mechanism have a translation movement in the direction indicated by the arrows in Fig. 5. Raising of rods 62 may then be accomplished by wheel 64 on the lower end of these rods riding up a fixed inclined surface it as the mechanism moves laterally. Downward movement of the rods is effected by rolling of wheel 84- from a raised track down an incline sloped in a direction opposite to that of 65.

Raising of the socket forming member is facilitated and injury to the mold is prevented by rotating the member to free it from the mold material just before and also preferably during at least the first part of the upward movement of rods 62. The socket forming member instead 3. forming member is brought down. toembed it in.

of being rigidly secured upon the end of arm 53 is therefore mounted thereon for rotation about a. vertical axis, such as being secured to ashaft 66 journaledin a bearing 6'! on the end of the and. To eflect automatic rotation of shaft 66 by translation of the mechanism I provide a fixed pin 68 disposed in the path of the teeth of sprocket 69 which latter is pinned or otherwise rigidly secured upon the upper end of shaft 56. As the mechanism is translated engagement of sprocket 69 with fixed pin 68 should occur just before wheel 64 starts to ride up the slope 65, as shown in Fig. 5. The engagement of the pin and sprocket to rotate the socket forming member should continue until it has been raised appreciably. The total rotation during this time may be only a fraction of a revolution, but this is all that is necessary to shear the member free from the moldmate'rial.

When the sprue tube socket has thus been formed, a length of rolled asbestos tubing is cut according to the height of the statichead of molten metal desired in the sprue for the particular job at hand. This is inserted into the socket and the mold is ready to be poured. As the pressure of the molten metal is exerted on the sprue tube it tends to expand and unroll, only the outer flap, as previously mentioned, being secured. The layers are thus pressed very tightly together tomake a strong body. The base, tending to split, is pressed more tightly against the walls of the socket, to aid in perfecting the seal between the mold and the tube end. Especially if the sheet of asbestos or similar material has a rough surface, the surface fibers of the tube tend to become embedded in the plaster of the sprue socket walls, and on the inner side to become impregnated somewhat with the molten metal, which bonding action both forms a tight seal and overcomes any tendency of the sprue tube to move lengthwise outward and to be forced out of its socket. Tendency of the tube to move lengthwise downward is, of course, prevented by abutment of its lower end with the thrust seat or wall 28. As shown, sprue A has a rim inwardly from the inserted tube I and its seat, so that the tube will not be forced downward by the infiowing metal to scrape mold material from the sprue. aperture. walls or tube seat which would contaminate the metal.

As my invention, I w

1. Apparatus for forming in a mold a sprue tube socket, comprising a sprue post upstanding from 15 2. The apparatus of claim 1, in which the base .of the inverted cup projects beyondthe mold and is apertured between the flange and the central portion of the base engaged with the sprue post, for admission of air to the interior of the inverted cup;

3. Apparatus for forming in a mold a sprue tube socket, comprisinga sprue post upstanding from the parting surface of a mold section into the mold body, and an inverted cup constituting a tube socket forming member, having a depending skirt with a cylindrical outer surface and 'a frustoconical inner surface divergent toward the rim of the cup, embedded in the mold back surrounding and spaced radially from said sprue post, and having a boss upstanding internally from the base oi the cup engaged with the end of said sprue post, and the base of said cup being apertured in the depression between said skirt and said boss for admission of air to the interior of the cup.

4. Apparatus for forming in a mold a sprue tube socket, comprising a mold form, a support therefor mounted for translation, a vertically reciprocable rod carried by said support, a sprue post upstanding from the bottom of said mold form, a tube socket forming member embedded in mold material contained in said mold form, an arm supported by one end upon the upper end of said rod, a shaft journaled in the other end of said arm and rotatably supporting said tube socket forming member on its lower endin a position overhanging saidmold form and in registry with said sprue post, a rotatable member fixed on the upper end of said shaft, a fixed member engageable with said rotatable member to rotate the sameupon translation movement of said support, and a cam surface engageable with the lower end of said rod by translation movement 01' said support substantially simultaneously with. engagement of saidrotatable and fixed members, and operable to move said rod upward by such engagement .for raising said tube socket forming member as the latter is rotated to free it from the mold material by rotation of said rotatable member engaged with said fixed member.

5. The apparatus of claim 4,'wherein the rotatable member is a sprocket wheel and the fixed member is a pin engageable by the teeth of the sprocket.

6. Apparatus for forming in a mold a sprue tube socket, comprising a sprue post upstanding from the parting surface of a mold section into the mold body, and a sprue tube socket forming member substantially co-axial with said sprue post and extending from the mold back inward toward the mold parting surface, the circumference of that portion of said socket forming member embedded in the mold being substantially constant throughout its length,-and the periphery of the extreme embedded end of said socket forming member being spaced a considerable distance laterally from said sprue post, such end forming a planar sprue tube end thrust seat adjacent to its periphery and perpendicular to the axis of said sprue post, and also defining a sprue rim of substantial width intermediate such seat and the sprue post.

'7. Apparatus for forming a sprue tube socket in a mold of frangible material, comprising a thin, tubular sprue tube socket forming member adapted to have one end thereof embedded in a mold back to a depth equal to at least several times the thickness of the thickest embedded portion of said member, for forming a socket groove to serve as the sole support for a self-sustaining sprue tube, and a sprue post protruding through the mold back for forming therein a sprue aper- (1 ture, encircled by said tubular member and spaced laterally inward therefrom at all points.

HENRY F. HAGEMEYER.

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