US1944359A - Slug casting machine - Google Patents

Description

Jan. 23, 1934. R R, MEAD SLUG CASTING MACHINE Filed July l, 1932 3 Sheets-Sheet 1 I 1 Ulli lli' ATTO NEYJ 3 Sheets-Sheet 2 R. R. MEAD SLUG CASTING MACHINE Filed July I, 1932 rn-37.- Q

Jan, 23, 1934.

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Patented Jan. 23, 1934 UNITED STATES SLUG CASTING MACHINE Richard R. Mead, Queens Village, N. YL, assigner to Mergenthaler Linotype Company, a corporation of New York Application July 1, 1939. serai No. 620,414 13 claims. (01.199-47) This invention relates to slug casting machines of the general organization represented in U. S. Letters Patent No. 436,532 to O. Mergenthaler, wherein a composed line of matrices is presented momentarily to one face of a slotted mold, a metal pot brought against the opposite face of the mold, and molten metal injected by a pump from the metal pot into the mold slot or cavity to form a type bar or slug against the line of matrices.

The type bars or slugs produced in this way, besides being used for direct printing, are employed extensively for the production of stereotype matrices from which stereotype plates are then cast for printing. However, the printing processes which have recently come into use, especially in newspaper work, require much greater pressureV to be exerted upon the slugs than heretofore in making up the stereotype matrices. This is especially true in the production of stereotypes by the so-called dry flong method, and it has been found in practice that some of the slugs have a tendency to break down under the increased pressure, this tendency being due to a spongy texture of the slugs caused by the presence therein of air holes which result from the mixing of air with the molten metal during the casting operation. Furthermore, the mixing of air with the molten metal often produces air holes in the character-bearing surfaces of the slugs, resulting in the production of imperfect impressions.

This mixing of air with the molten metal durm ing casting is due either to improper venting of the mold cavity or to improper injection of molten metal thereinto, or both. Mold venting, as ordinarily practised in the commercial linotype machine, is open to certain objections, which it is one of the objects of the present invention to obviate. Various factors contribute to the improper injection of molten metal into the mold cavity, and a few words of explanation may be useful before stating how this defect is overcome by the present invention.

The delivery passage formed in the throat section of the metal potilares laterally from the pump cylinder to the mold-contacting mouthpiece, so that at the latter place the width of the passage is approximately equal to the length of the longest mold slot (in some machines 42 ems). The area of the delivery passage is such that ordinarily a uniform volume of metal can be forced therethrough by the metal pump at a suiiicient rate of flow and under sufficient pressure to fill the mold completely and to expel all of the air therein before the metal in the mold begins to solidify. However, as the throat section is now made (being cast integral with the metal pot), the surface defining the delivery passage is rough,

unfinished, and more or less spongy or porous,

as a result of which molten metal accumulates thereon and gradually decreases the area of the passage.

As the area of the delivery passage becomes more and more restricted, the operation of the metal pump fails to displace the required volume of metal to lill the mold cavity rapidly enough to produce good castings of the large size slugs. This faulty casting may take place even though the air venting system is operating perfectly, but of course where there is improper venting, the condition is aggravated.

The foregoing difculties are most troublesome in the case of the larger ribbed slugs which are formed with overhanging character-bearing surfaces, and unless these slugs are properly cast not only are their body portions structurally weak but their overhanging character-bearing surfaces are also weak and ragged, causing the slugs either to break down in use or to produce imperfections in the printed matter.

The present invention is intended to overcome these and other difficulties, and provides a metal pot having a throat section constructed so as to prevent or minimize the accumulation of metal on the surfaces thereof which define the` metal delivery passage, whereby a definite throatarea will be maintained and the delivery of molten metal to the mold cavity will be uniform. The invention also provides for the venting of the mold cavity in a manner which will insure a complete expulsion of the air at each casting operation.

More speciiically, the invention contemplates a metal pot throat section with two passages, one, the metal delivery passage, leading from the pump well to the mouthpiece, and the other, a metal return passage, leading from the mouthpiece back to the metal pot and through which the air is vented from the mold cavity.

In carrying out the invention, the throat section is made in the form of a built-up structure, whereby those surfaces of the parts going to make up the metal passages may be machined before being assembled and secured in place to provide smooth finished surfaces to which the molten metal will not adhere.

In the accompanying drawings, the invention has been shown merely by way of example and in preferred form, but obviously many modifications and variations may be made therein without departing from the spirit of the invention. It is t be understood, therefore, that the invention is not limited to any specific form or embodiment except insofar as such limitations are specified in the appended claims. Y

eferring to the drawings:

Fig. 1 is a sectional elevation -of the improved metal pot, and showing the pot in mold contacting or casting position;

Fig. 2 is a top planl view of Vthe metal pot, with the mouthpiece omitted;

Fig. 3 is a front elevation of the pot throat section, with the mouthpiece omitted; and

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 1.

Referring particularly to Fig. 1, the metal pot A is similar to those used in the commercial linotype machines and contains a pump well B, in which is tted a piston or pump plunger D adapted to be moved downwardly at appropriate times by a spring, not shown, to force the molten metal through a delivery passage C in the throat section C', the latter hav-ing a mouthpiece E, which is adapted to form a metal-tight t against the rear face of arslug casting mold F. The mold F is carried by a rotatable disc I-l and, as usual, comprises a body piece F and a cap piece F2, which pieces are separated at opposite ends by so-called liners forming the end walls of the mold slot or cavity F3 in which the slug is cast. During casting, the front face of the mold cavity F2 is closed .by a composed line of matrices G bearing in their rear edges intaglio characters which correspond to the type characters to be formed on the printing slug.

Normally the molten metal is kept at a uniform level in the pot A, and when the pump plunger `D is retracted after the'casting operation, the

metal in the delivery passage C recedes to the same level, as indicated in Fig. l. As the metal recedes, air is drawn into the delivery passage, so that prior Yto each casting operation that part of the passage above the metal will be lled with a body of air. As shown in Figs. 2 and 4:, the delivery passage C flares laterally from the narrow width of the pump well B to a much greater width corresponding to the maximum length of the mold slot. Thus, it will be apparent that the throat section contains a large volume of air, and it is this air plusk the air conned in the mold cavity which must Vbe vented completely at each casting operation to prevent its mixing with the molten metal which goes to form the slug.

As before stated, it is the purpose of the present invention to provide the throat section with two passages having smooth surfaces to which the molten metal :will not adhere. To this end, the throat section is built up of separate parte, and comprises essentially a bottom portion l, a top portion 3, and an intermediate portion 2, said portions being separated so as to define between them two passages, one the metal delivery passage C already referred to and an air venting and metal return passage C2 leading from the mold back to the metal pot.

The bottom portion l is cast integrally with the metal pot A, being formed along opposite edges with raised ribs 4 and 5. The intermediate and top portions 2 and 3, respectively, are made separately and are adapted to be secured in place, subsequent to further manufacturing operations, to complete the composite structure. The intermediate portion 2 is made in the form of a thin plate having a thickened forward end 6 adapted to form the upper part of the forward end of the throat section, and the top portion 3 is in the form of a flat plate adapted to form the top wall of the throat section.

Before the portions l, 2 and 3 are secured together, the upper surface of the bottom portion 1 and the inner surfaces of the raised ribs 4 and thereon are machined and polished or otherwise treated to maize them smooth and to provide a channel of definite cross-sectional area. The intermediate plate 2, the opposed surfaces of which have also been machined or otherwise treated to render them'smcoth, is placed upon and secured, as by welding at X, to the raised ribs 4 and 5 of the bottom portion 1, the top surfaces of which have had the casting roughness removed so as to insure a fluid-tight nt of the portion 2 thereon. This intermediate portion 2 formed on its upper surface with two ribs 7 and ruiming longitudinally thereof and which di" vide the passage C2 into three sections 9, l() and ll, as will be later referred to. Along its opposite edges, this intermediate portion is provided with shoulders l2 and 13 adapted to support the top pla-te 3, which is secured thereon by welding as at X', its inner surface also having been machined so that the passage C2 formed between the `intermediate plate 2 and the cover plate 3 will be defined by smooth surfaces, as desired.

The front face of the forward end 6 of the portion 2 Yis provided with a longitudinal groove 14 and three fore-and-aft channels l5, 16 and 17 leading therefrom to the sections 9, 10 and 11, respectively, of the passage C2. Channelsl, 19 and 20 are also drilled through the wall of the metal pot A tofform communications between the sections 9, i6 and 11, respectively, and the interior of the metal pot A, these channels terminating'below the normal level of the molten metal therein. To provide material through which these channels may be drilled, the Wall C3 within the metal potv A is thickened as indicated at C4. Thus the second or air venting and metal return passage`C2 is formed in the throat section C' immediately above the metal delivery passage C. Furthermore, the top portion 3 is provided above the sections 9, l0 and 11 with openings 28, 29 and 30, respectively, through which the Yair vented rom the mold cavity is passed oif into the atn mosphere, thus preventing the necessity of forcing it out by way of the metall pot A and also preventing the creation of a vacuum within the passage C2.

Intermediate the length of the throat section C, and on opposite sides thereof, two hollow members 21 and 22 are fastened to the throat section by bolts or screws 23. These members engage and align with perforated lugs 24 and 25 cast integrally with and opening below the bottom portion'l of the throat section C, said members and lugs forming ilues for carrying olf products of combustion from the metal pot heating burners, all in the usual manner.

The mouthpiece E, which as already stated is animatedV to form a metal-tight fit with the rear face of the mold, is rigidly secured at the top to the forward end 6 of the intermediate portion 2 of the throat section C and at the bottom to the forward end of the bottom portion 1 thereof. The mouthpiece E, in the present instance, is provided with a rectangular slot E adapted to align with and form a continuation of the delivery passage C, and above the slot E there is provided a series of perforations E2, extending through the mouthpiece from front to rear.

its

the rear of the mouthpiece, the perforations E2 (shown in phantom in Fig. 3) align with the longitudinal groove 14 formed in the front face of the forward end 6 of the intermediate portion 2, which groove, as already stated, is in communication with the air venting and metal return passage C2.

In operation, the molten metal is forced from the well B by the pump plunger D through the delivery passage C and into the mold cavity F3, each pump stroke displacing a uniform volume of metal under uniform pressure and at a uniform rate of flow. At each injection, the metal moves before it the volume of air contained in the upper portion of the delivery passage C, which air enters the mold cavity F3 and is vented therefrom through the perforations E2 of the mouthpiece E and into the venting and metal return passage C2 by way of the groove la and channels 15, 16 and 17, and from the passage C2 into the atmosphere through the holes 28, 29 and 30 formed in the top portion 3 of the throat section C.

The smoothness of the surfaces .defining the metal delivery passage C prevents the accumulation of metal thereon and so the denite crosssectional area of the passage is maintained. The uniform operation of the pump plunger D is, therefore, not affected and each operation thereof fills the mold cavity F3 completely and rapidly enough to expel all of the air from the cavity before the metal therein begins to solidify, irrespective of the size of the mold in use at the time.

The particular mold illustrated is of the headletter variety provided with core members F4 depending into the mold cavity F3 from the cap piece F2, the rear edges of the core members F4 being in vertical alignment with the rear face of the mold and the front edges of said core members terminating short of the front face of the mold. Since the slot E' of the mouthpiece E aligns with the cavity of the mold between the upper surface of the body piece F and the lower edges of the core members F4, the inrushing metal during casting continues forwardly through the lower portion of the mold cavity until it strikes the line of matrices and then fills the mold up from front to rear, so that the upper rear portion of the mold cavity is the last part to be filled. Because of this, the air is expelled from the forward part of the mold cavity rearwardly, as indicated by the arrows.

The air is more completely vented than ordinarily since some of the metal escapes through the venting passages before solidification of the metal in the mold cavity takes place, thus causing the metal to force the last vestige of air out of the mold before `it becomes congealed. Because of the thinness of the intermediate portion 2 of the throat section C', heat from a burner located immediately below the bottom portion 1 of the throat section and from the metal passing through the delivery passage C maintains the temperature within the passage sufficiently high to keep the escaping metal therein always in a molten condition. Besides, the surfaces defining the passage C2 being smooth, very little resistance is offered to the flow of the metal, so that it passes readily through the passage and into the metal pot A and never clogs up the air venting system.

The throat section C has been shown and described as a composite structure preferably made up of a plurality of portions permanently secured together as by welding. This is desirable and practicable because of the fact that the passages .section is seldom necessary.

C and C2 are dened by smooth surfaces'to which the molten metal will not readily adhere, and therefore access into the interior of the throat It is within the scope of the invention, however, to construct the throat section of a plurality of parts detachably secured together so that when the passages therethrough are dened by surfaces not made smooth and metal does accumulate thereon, the parts may be readily detached for purposes of cleaning. In this'respect, the scope of the invention includes a metal pot having a composite throat section built up of a plurality of detachable parts.

Having thus described my invention, what I claim is:

1. In or for a slug casting machine, a metal pot having a throat section built up of a plurality of separately formed parts and provided with a passage through which molten metal is adapted to be forced into the mold, the surfaces defining said passage being made smooth to prevent the accumulation of metal '.hereon.

2. In or for a slug casting machine, a metal pot having a throat section built up of a plurality of separately formed parts and provided with two passages; one to deliver to the mold molten me al discharged from said pot, and the other to return molten metal from the mold to sad pot, the metai delivery passage having smooth surfaces to prevent the accumulation of metal thereon.

3. In or for a slug casting machine, a metal po' having a Well adapted to contain a supply of molten metal, and a throat section built up of a plurality of separately formed parts and provided with two passagescommunicating with said well, one of said passages being adapted to have molten metal forced therethrough from said well, and the other of said passages being adapted to return molten metal to said well, both of said passages being dened by smooth surfaces to prevent the accumulation of metal thereon.

4. A metal pot as set forth in claim 2, characterized by the fact ihat the two passages are separated from each other by a thin partition, whereby the heat of the molten metal passing through the first-mentioned passage aids in keeping the metal passing through the second-mentioned passage in a molten condition.

5. In a slug casting machine, the combination of a mold, and means for injecting molten metal into the mold, including a metal delivery passage leading to the mold, said passage being built up of a plurality of separately formed paris and having smooth surfaces to prevent the adherenceA leading to the mold, said passage being built up of a plurality of sections having smooth surface portions which define the metal delivery passage.

7. In a slug casting machine, the combination of a mold, a metal pot having a built-up throat section adapted to contact with the mold and having a passage through which metal is forced into the mold, and a pump plunger in said metal pot for displacing a uniform volume of metal to ll the mold, the passage of the throat section having an area definitely proportioned with rey spect to the volume of metal displaced by the pump plunger and defined by smooth surfaces to prevent the accumulation of metal thereon, whereby its definite area is maintained.

8. In a slug casting machine, the combination of a rnold, a metal pot having a throat section adapted to contact with the mold, and a pump plunger in said metal pot for injecting a uniform volume of molten metal into the mold under uniform pressure, the throat section being provided with two superimposed passages and being made up of at least three separate parts rigidly secured together, thereby permitting the opposed surfaces of the parts to be machined so that the passages defined thereby may be rendered smooth, one of said passages being adapted to deliver the molten metal from the pot to the mold, and the other passage being adapted to carry on" the air vented from thermold cavity and to return to the metal pot the metal escaping from the mold cavity with the vented air.

9. In or for a slug casting machine, a metal pot having a throat section provided with a passage through which molten metal is adapted to be forced into the mold, said throat section being built up of a plurality of paris rigidly secured together in a fluid-tight manner.

10. In or for a slug casting machine, a metal pot having a throat section provided with two passages, one to deliver to the mold molten metal discharged from said pot, and the other to return molten metal from the mold to said pot, the throat section being built up of a plurality of parts rigidly secured together in a fluid-tight manner.

11. In or for a slug casting machine, a metal pot having a throat section provided with two passages, said throat section being made up of three separate parts rigidly secured together in a iiuid-tight manner, the three parts being arranged in superimposed relation with opposite sides of the intermediate portion forming each a surface of one of the passages.

12. A metal pot as set forth in claim 10, characterized by the fact that the two passages are separated from each other by a thin partition, whereby the heat of the molten metal passing through the inst-mentioned passage aids in keeping metal passing through the second passage in a molten condition.

13. In a slug casting machine, the combination o1" a mold, a metal pot having a throat section adapted to contact with the mold, and a pump plunger in said metal pot for injecting molten metal into the mold, the throat section comprising top and bottom portions and an intermediate portion separated from one another to dene a metal delivery passage and a superimposed venting and metal return passage, said intermediate portion forming a thin partition between the two passages, whereby the heat of the molten metal passing through the metal delivery passage aids in keeping the metal passing through the venting and metal return passage in a molten condition, said portions `being rigidly secured together in a huid-tight manner.

RICHARD R. MEAD.

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