US2232432A - Typographical mold and slug - Google Patents

Description

Feb. 1s, 1941. l y J, W, BITTNER 2,232,432

TYPOGRAPHICAL MOLD AND SLUGv Filed Aug. 28, 1940 2 Sheets-Sheet 1 INVENTOR JOHN W.BITTNER Bvvy//m ATTORNEY Feb. 18, 1941. J. w. BITTNER TYPOGRAPHICAL MOLD AND' lSLUG 2 Sheets-Sheet 2 Filed Aug. 23, 1940 Lle Fig.

l: Ei ii Il ll II r\ il lNvENToR JOHN W. BITTNER BY%/dw lATTORNEY f. A E

Patented Feb. 1c, 1941 `UNITE-D STATES PATENT OFFICE ration of New Yo'rk Application Agllst 28, 1940, Serial No. 354,510

3 Claims.

This invention relates to improvements in connection with typographical slug casting machines and is directed incre particularly to the problem of shrinkage of character bearing type slugs cast in the molds employed in such machines, for example, as' described in Letters Patent No. 436,532 granted September '16, 1890. A

'The factor o'f slug shrinkage has always been a source of annoyance and costly diiiciilties in l composing rooms due especially to the resultant variations in the body thickness (point size of the slug body) at ldiierent points throughout the length of the cast slugs. Ithas been established that the slower the rate of cooling of the l5 type metal injected into the slug casting mold, the greater the arnouhtyof shrinkage of the type slug. Moreover, it is generally true for dinerert designs 0f molds that the Ygreater mass 0f metal constituting the end portions of the molds gi, serves to conduct away or absorb the heat from the ends f a cast Slug more rapidly than from the central porti-ons oi lthe slug body. while the first few slugs cast in a` Cold mold may measure to size throughout, as soon as the mold :5 becomes relatively hot the central regions' of the body of successively cast slugs` cool or chill more slowly than the ends with the result that while the sli-lgs are invariably accurate to size toward the ends they are undersiie as to thickness along lo the central portions of the body, the more rapid coolingv f the ends resulting in drawing partially solidified metal from the central regions.

wig to the smaller mass of metal in the body of slugs which are cast to relatively short meas- 35 lires, the factorof shrinkage is usually so small as to be negligible from a practical standpoint. However; with long measure slugls the shrinkage factor is so great as to be quite objectionable and very diilicult to contend with. This is especially D the case when, according to modern practice, standard Sil-ein measure slugs are cast in the production of short lines ,for newspaper colurnns (l2-ems frHsingle-'column and 18-ems for double-clumn) the machines being l equipped ,5 with apoyar' driven saw for cutting off the desid r 18`=erh pertis as the BO-ern slugs are ejected; Now it will be evident that if the centr'al prltie'h of a ilerh bdii is undersize in thickness; as always the case due to the faco t'r of` shrinkage, the inli end f a Short p0rtin may be off will be thinner than the outer' end thereof. Accordingly, 'when' groups f such short slugs are compactly assembled colunnwise tlieprintirg' form they will natural- 55 1y runiiiore and more out of parallelism as the length of the column increases and thus produce printed lines' having' a fan-like appearance. 'Ihis non-parallel condition of slugs arising from the shrinkage factor exists in spite of the well known slug trimming operation wherein slender verti- 5 cally disposed trim ribs spaced usually at twoem` intervals are provided on one side of the slug body for-the purpose `of shaving the slug to a uniiorrn thickness as it is pushed by the usual ejector through a pair of trimming knives. 'I'he 10 fact is that the amount of shrinkage within centra-l regions oi the slu'g` body is so great that on its uni-,rimmed side only the end portions are shaved by the trimm-ing knife operating on this side f the slug body. The present invention aims to compensate for the factor of shrinkage by a novel expedient which has Vbeen discovered only after long and tedious exper-imentation, the invention in its broadest aspect involving the provision of one 20 or more slots extending part way vertically through the slug body so that the composite cast slug comprises a plurality of constituent and partially segregated mass sections all stably connected together, the eiiect being to confine shrinkage to several relatively small mass portions of the body of relatively long slugs and thus simulate the condition, as with relatively short cast slugs, of a negligible or at least unobjectionable amount of shrinkage in each portion. i

Specifically,L and to` this end,- the invention provides a mold having one or more core members` in the form of thin fins running fore and aft of the longitudinal casting slot, such members being 3S carried preferably bythe cap element of the mold and extending from the rear edge thereof forwardly to a point little more than midway of the depth of the cas-ting slot. According to different embodiments of the invention these fins,l which mayaptly be termed shrinkage controlling or shrinkage slot producing fins, may project either entirely or only partially across the vertical height of the casting slot, their projection within said slot in either case producing corresponding narrow slots which serve to partially divide up the mass of the slug body into a plurality of constituent and relatively small mass sections each of which, upon cooling, will shrink a uniform and negligible amount.v

It is important that the aforesaid shrinkage controlling fins be made thin and extend but little more than midway depthwise of the mold, the advantage being that while the slots `produced thereby penetrate into the slug body an extent suii'icient to effectively divide up that portion of the mass of the body in which the greatest shrinkage strains normally occur, they are so narrow and shallow as not to impair the strength of the slug in a vertical direction to withstand printing pressures. Further, by terminating the slots produced in the slug body well below the character bearing edge thereof the latter is unbroken and thus adapted at all points in its length to support type characters which may be cast thereon in producing lines of different lengths. Moreover, by forming the shrinkage controlling ns as thin as possible (something less than the vertica1 height of the portion of the mold slot in which the main or body portion proper of a slug is cast has been found adequate for all conditions) the slots produced thereby in the slug body are so narrow as not to intersect or otherwise interfere with the usual vertical trim ribs, and to enable conning the slots to line measure locationsI that are rarely used, thus assuring square ends on all useful short line character bearing portions which it may be desired to saw oif a longer slug.

Should the vertical projection of the iins referred to be such as to form along the casting slot intermediate closed walls of partial fore and aft ldepth the slots produced thereby in the cast slug will extend entirely through the thickness of the slug body but the divisional mass portions of the body will remain connected together by solid necks of metal above the slots. If on the other hand the vertical projection of the ns is such as to form along the casting slot intermediate but somewhat open walls of partial fore and aft depth, then the slots produced in the slug body will extend only partially through the thickness thereof and the divisional mass portions of the slug body will be connected together by the necks of metal above the slots as before plus a thin web spanning each slot at one side thereof, such web being formed obviously by flow of the injected type metal around the openings left by the shallow or vertically foreshortened ns.

Another feature resulting from the shrinkage controlling ns herein provided is that they serve to firmly retain the slug in place within the casting slot at the time of breakaway of the metal pot, it being well known to those familiar with these machines that especially under slightly cold conditions of the mold, the type metal, or the pot mouthpiece, there is a denite tendency for the slug to be drawn backward in the mold to a slight extent during breakaway with' the result that the slug is trimmed below proper type-height by the usual back trimming knife.

In the accompanying drawings:

Figure 1 is a front elevation of a well known form of type slug casting mold having the shrinkage slot producing fins of the invention.

Figure 2 is a plan View of the underside or casting face of the upper or cap element of the mold shown in Figure v1.

Figure 3 is a section, taken on the line 3 3, of the mold in Figure l and viewed in the direction indicated by the arrows.

Figure 4 shows a type slug cast in the mold in Figure 1, the slug being viewed from the plain side of its body which side is cast against the inner face of the lower or body element of the mold.

Figure 5 is a section, taken on line 5-5 in Figure 4, viewed in the direction of the arrows.

Figure 6 is a front elevation of a well known form of type slug casting mold differing in design from that of the mold shown in Figure 1, this mold being provided with shrinkage slot producing fins of slightly shallow vertical height according to an alternative embodiment of the invention.

Figure 7 is a plan view of. the underside or casting face of the upper or cap element of the mold shown in Figure 6.

Figure 8 is a section, taken on the line 8--8, of the mold in Figure 6 and viewed in the direction indicated by the arrows.

Figure 9 shows a type slug cast in the mold in Figure 6, the slug being viewed from the plain side of its body which side is cast against the inner face of the lower or body element of the mold.

Figure 10 is a section, taken on the line Ill- I0 in Figure 9, viewed in the direction of the arrows.

Similar parts are designated by the same reference characters in the different figures.

For purposes of illustration the invention is herein shown as applied to type slug casting molds of well known construction and adapted for mounting on a so-called mold carrier or disk which is rotatable by power in order to present a selected mold rst in horizontal position for the slug casting operation and thereafter, by rotation of the disk, in vertical position for the slug ejecting operation. At ejecting position the cast slug is pushed forwardly out of the mold slot by the advancing action of a selected ejector blade of the proper size, the slug being moved edgewise thereby through a pair of opposed trimming knives for the purpose of shaving its side faces and thus bringing the body to a uniform thickness throughout its length.

The construction and manner of operation of the aforesaid mold disk, slug ejecting devices and trimming knives are too well known to require detailed explanation here and since these parts in one or another accepted arrangement may be used in connection with the present invention and form no direct part thereof, they are not shown in the drawings. 'I'he only exception over usual or standard construction is that the shrinkage controlling iins provided in the mold according to one embodiment of the invention require the provision of corresponding slots in the slug ejector blade in order that the latter may pass through the mold slot. Such slotted ejector blades, however, are also well known in the art in connection with so-called tabular and logotype producing molds having partitions running thev full fore and aft depth of the casting slot to produce a plurality of separate slugs at each cast, all as' evidenced by the disclosures, for example, in U. S. Letters Patent Nos. 609,883; 635,- 305 and 1,082,059.

Referring to Figure 1, the numeral l designates the body element of the mold, which element is rigidly secured to the usual mold carrier or disk. The cap element 2 is suitably and firmly secured to the body l and by means of interposed liners 3 and 4 of selected thickness the opposed inner faces 5 and 6 of the body and cap elements respectively are held separated from one another a predetermined distance to thus form the side and end walls of a. longitudinal slug casting slot 1 of desired height or point size. At the proper time molten metal is injected at the rear of the slot 'I which is closed at the front by a line of matrices presented edgewise to the front of the mold and held in clamped condition endwise of the line by the usual vise jaws in the machine, the characters of the matrices being thus reproduced on the front or character bearing edge of the cast slug.

As heretofore, the wall 5` of the mold slot is plain or smooth while the wall 6` is` provided as usual with e number of narrow, shallow and forwardly tapering cross grooves 8 which produce on the corresponding side ofthe body of the cast slug slim raised trim ribs 9, these ribs `being shaved in well kno-wn manner by the customary side trimming knives during the slug ejecting operation for the purpose of bringing the slug body to a uniform thickness throughout its length.

The grooves 8 may be spaced laterally at arbitrary intervals in different types of molds but for most purposes an even spacing at 2-em intervals isI employed. Moreover, the depth of the grooves may diifer in different molds but in any case it will be clear that the actual point size or thickness of the cast slug is represented by the measured thickness, after trimming, between the plain side of the body and the trimmed surface of the ribs on the opposite side.

As already pointed out, the body thickness or point size of slugs, especially those of relatively long measures, varies as between the ends and central portions thereof in spite of the aforesaid trimming operation. The fact is that the central regions of the slug body which always cool more slowly than the ends shrink to such extent that the plain side of the body over an' area from onequarter to one-half inch from the ends and, at its highest point, a fraction below the top edge of the slug is somewhat concave. From this it will be evident that the plain side of such a slug will be touched by the corresponding trimming knife only toward the ends thereof and along aline adjacent to the character bearing edge. Thus, in practice, it is a common experience to nd one end of a 12-em or an l-em porion sawed ci a .S-em slug thinner than the other end thereof, an objectionable condition of long standing and very diiiicult tocontend with in making up print-' ing forms.

To overcome'this condition the present invention provides means in the slug casting mold for dividing or breaking up the injected molten metal and consequently the mass of the slug body into a plurality .of constituent and partially segregated short mass portions or sections all of which remain connected together so that a composite slug is cast having substantially the stability and strength of any standard slug of similar size and having an unbroken character bearing edge of full strength and point size throughout the length of the slug. For this purpose the casting slot l, which in the mold shown in Figure l may be assumed to be Bil-emsin length, is provided over a portion of its depth from the rear face I9 to the front face II of the mold with slender fore and aft cores or ns l2 which may be formed integral with the cap element 2 of the mold as herein shown or may be otherwise secured to at least one of the mold elements, the sides of the ns I2 being preferably tapered forwardlyas best shown in Figure 2 in order to permit free forward movement of the cast slug during ejection.

It will be observed that while the fins l2 project entirely across the vertical height of the casting slot l, as clearly shown in Figure 1, they terminate in a fore and aft direction well back of the front face II of the cap element 2 and in fact extend little more than midway depthwise of the casting slot 1 as will be seen from FiguresZ and 3, thus forming along the slot intermediate closed walls of partial fore and aft depth. Moreover, the fins I2 are so thin setwise that they are conned to only a small fraction of the area between the cross grooves 8 in the casting face of the cap element 2, thus avoiding intersection with such grooves and consequent loss of the surface of the trim ribs formed. thereby on the cast slug, and are also restricted within the limits of line measures that are rarely used such as 91/2-em and lill/rem measures a-s indicated.

It will now be apparent that the presence of the shrinkage controlling i-lns` I2 within` the casting slot of the mold results in the formation in the cast slug I3, Figure 4, of corresponding narrow shrinkage slots I4 extending from the bottom of the slug body upward therethrough to a point little more than midway of the vertical height of the slug, thus leaving a substantial body or neck of metal I5, Figure 5, between their upper ends and the top or character bearing edge I 6 of the slug. The slots I4 will be seen to occupy or extend setwise over only a very small part of the slug body between adjacent trim ribs 9, indicated by the dotted lines in Figure 4, and to be confined to and located setwise along the slug body at the rarely used line measure positions mentioned above and indicated by the em scale shown in Figure 4'.

Thus, the slots I4 partially divide or segregate the mass of the slug body into a plurality of relatively short' constituent mass portions each subject to a minimum, uniform and practically negligible amount of shrinkage and all connected together by the solid necks of metal I5 so as to constitute a composite slug of substantially the same stability and strength in a vertical direction as if the slots did not exist. Moreover, the character bearing edge I6 of the cast slug is of full point size throughout and unimpaired in strength` vertically so that type characters may be cast thereon and adequately supported thereby at all points. Accordingly a line of any desired length ysuch as the 12-em line of characters I'I represented in Figure 4 may be cast on a slug of longer measure and the short portion of the slug containing such line sawed 01T for subsequent use alone. Due to the narrowness and the location of the slots I4, it will be apparent that short portions containing', 10), 18 or 20-em lines may be sawed on without intersecting the slots I4 so that by a single cutting operation in severing any such short portions the ends adjacent to the cut will be square over their full height, a feature which is not only desirable but also quite necessary for most purposes.

An alternative embodiment of the invention is shown in Figures 6 to 10 inclusive wherein shrinkage controlling fins I8 are provided on the casting :face I9 of the cap element 29 of a mold differing in designfrom that shown in Figure 1. In this instance the fins I8 which are similar to the fins I2 described above differ from the latter in the single respect that they project only partially across the vertical height of the casting slot 2I as clearly indicated in Figures 6 and 8, thus forming along the slot intermediate but somewhat open walls of partial fore and aft depth. In practice it is desirable that the fins project at least half way across the height of the casting slot so that the shrinkage slots produced thereby penetrate an effective depth into the mass of the slug body, that is, deep enough into the thickness of the body to effectively break up the mass thereof. With this arrangement it will be evident that molten metal injected into the casting slot ofthe mold will flow around the vertically foreshortened ns I8.

and produce thin webs 22 of metal spanning each slot 23 formed in the cast slug by the fins,

' such webs being formed at the side of the slug which is cast against the smooth wall 24 of the body element 25.

The slug 26 cast in the mold shown in Figure 6 is shown in Figures 9 and 10 and this slug will be seen to simulate the slug I3 in Figure 4 except for the presence of the aforesaid thin webs 22 which are clearly discernible in the section of the slug shown in Figure 10. The presence of the webs 22 add of course to the ability of the slug to resist deformation but of greater importance still, such webs definitely assure, upon a single cutting operation, square ends of full vertical height on any short line bearing portion that may be sawed oi even though the cut may intersect one of the shrinkage slots 23.

Shrinkage controlling ns projecting entirely or only partially across the vertical height of the casting slot may be used in either of the types of molds shown and, as will be apparent to those skilled in the art, such ns may be used in connection with a wide variety of similar molds including the well known types of recessed molds commonly employed on slug casting machines. In fact, effective compensation for shrinkage has resulted from the provision of shrinkage controlling fins which fall short of the vertical height of the casting slot by an amount sufficient to avoid the necessity of slotting the usual form of slug ejector blade or to require only a slight channeling of the surface of the blade to clear the ns, and fins so foreshortened in projection across the casting slot may indeed be employed if desired.

The principal requirements are that regardless of the particular type of mold in question or the `precise shape, size, number, location or vertical projection of the shrinkage slot producing fins provided, the slots penetrate into and thus effectively break upthat mass portion of the slug body which is subject to excessive shrinkage into constituent partially segregated but rmly connected mass portions none of which are susceptible to an objectionable amount of shrinkage, and this without weakening the Vertical strength of the slug, when used as a whole, to withstand printing pressures, without weakening or reducing the width of the chara-cter bearing edge at any point, and without losing the facility to obtain by a single cut square ends on adjacent short slug portions of any desired line measure that may be desired to cut from a longer slug having the shrinkage slots in the body thereof.

As previously stated, the shrinkage' slot producing fins described serve also to rmly retain the slug in place in the casting slot of the mold at the timeof breakaway vof the usual metal pot. This willbe clear by lcomparing the slug I3 in Figure 4 with the casting face of the mold cap element in Figure 2 against which face the ribbed side of this slug was cast. By superposing the slug on the mold cap shown in Figure 2 it will be seen that the fins I2 definitely anchor the slug against backward movement, that is, movement in a direction away from the front edge I I of the cap.

I claim as my invention:

l. A typographical slug casting mold comprising spaced cap and body elements the innermost opposed longitudinal surfaces of which are substantially parallel and provide walls defining the minimum vertical height of the casting slot, a plurality of fore and aft fins projecting into the space between the aforesaid longitudinal surfaces and having a maximum setwise width materially less than the vertical distance therebetween and said fins having tapered sides extending forwardly from the rear face of the mold to a point of intersection about midway of the fore and aft depth of the casting slot, whereby to provide inthe mass portion of the slug body formed by the aforesaid walls shrinkage slots beyond the width and extent of which the slug body is at least the full thickness as determined by the vertical height between said walls.

2. A typographical slug casting mold having a casting slot formed by vertical end walls and upper and lower longitudinal walls, the latter walls beingsubstantially parallel continuous surfaces in their respective planes, at least one fore and aft fin projecting vertically across the casting slot between the aforesaid longitudinal walls, said fin having oppositely tapered sides extending from the rear face of the mold forwardly to a point of intersection about midway of the fore and aft depth of the casting slot and ing to claim 2, wherein the upper longitudinal' wall of the casting slot is provided with a plurality of shallow fore and aft grooves for forming trim ribs on the corresponding side of the cast slug, and wherein the specified fore and aft iin is located at a fractional line measure position along the casting slot and confined to a fraction of the space Ibetween adjacent shallow grooves.

J OI-IN W. BITTNER.

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