US1657444A - Process of and means for preparing molds - Google Patents

Description

Jan. 24, 1928. 1,657,444

c. K. PRINCE PROCESS OF AND MEANS FOR PREPARING MOLDS Filed Oct. 6, 1926 5 /3 6 2a erzo 76 Li 67166 ill , Patented Jan. 133218.

unrrno STATES 6.71.. ARENCE PATENT ()FFICE.

ESTBATOB 0F SAID OLABEI-ICE K. ERINGE, DECEAESED.

PROCESS OF AND MEANS FOR PREE'ARING MOLDS.

Application filed October 6, 1926. Serial No. 139,843.

This invention pertains to the art of preparing molds for use in casting molten materials, fo example, iron, and relates more particularly to a process of reinforcing green sand prints, to a mold having such a reinforced. print; and to a reinforcing or retaining :vice for such prints.

in castin thin-walled cored articles, of which a rad or section is herein specifically referred to by way of eir'unple, it is of vital importance to support the core accurately and iirnilv within the mold cavity, since the movement of the core relatively to the sides of the mold cavity results in the production of a casting ha thin spots or holes its walls, it worthless tor the purpose for which it was designed. Khan the casting; is to have an opening or openings leading to its interior, the core must be united to the side wall of the cavity at the point where the opening is to e formed, h member or print which unites the core and cavity wall may bean integral projection upon the core, termed a core print, or it may be a protuberance upon the wall of the mold proper, 1n the latter case being commonly known as a green sand print. "il hichever type of print be employed, such print should constitute reliable guide means to facilitate the location of the core within the ,mold cavity and should also furnish an adequate and firm support for adjacent portions of the core. Those parts the core winch are remote from the print or prints, are supported in proper position relative to the sides of the mold cavity by means of metallic supports or chaplets, the number of such chaplets varyingwith the length and size of the core t he supported. When the core is of any c crable length, the accurate and careful g'ilacing of the necessary number of chaplets consumes considerable time, while, moreover, as the c liaplets are embedded in the finished casting and can not again be used, their cost is a considerable item of expense to the founder.

l i hiie core prints are commonly used, they are open to certain serious objections, for exan'iple, when they are of small diameter or of substantial length they tend to warp during baking so that they no longer accurately coiitorm to the position of the desired openin the casting. Such core prints turinadequate assistance to the molder in placing the core, and if warped or twisted may greatly delay him in his efforts to produce accurate work. Furthcrn'iore, in order to provide the requisite draft in making the core, it is necessary to make the core print taper outwardly from the body of the core. This produces an opening in the casting which tapers outwardly, although in many cases, for example, in the manufacture of radiator sections, itis desirable to have the opening in the casting taper inwardly, and thus it a core print be used, an excessive re moval of metal by machining is necessary in order to provide an opening of the desired taper in the casting.

[is compared with the core print, the green sand print would have none of the above disadvantage since, first, it could be produced with great accuracy by the more provision of an openingin the pattern to receive the sand, and as the mold is not baked, such green sand print would not warp or twist; secondly, it is comparatively easy to provide the core with a shallow socket for the reception of the inner end of such a green sand print, since such a socket is but little affected by baking and thus retains the accuracy of location originally imparted to it. Thus the molder could locate" the core accurately and quickly merely by setting the socket of the core over the green sand print; thirdlyv the taper of a green sand print in inward, like that of the open ing desired in the casting, so that but little machining of the casting would be required if a green sand print were employed.

Thus, the green sand print would possess several desirable characteristicsnot found in the core print, but heretofore it has generally been considered impractical, under many conditions at least, to use the green sand print for this purpose on account of its friability and lack of strength. I have new discovered a )rocess of molding in which all of the advantages of the green sand print may be availed of and to: this endhave devised a reinforce device or retainer for such a green sand, print, by. means of which the print may be made sufficiently strong and still to retain the shape originally in'iparted to itduring molding, and by the use of this rig-id green sand print I am able to posi ion t 1c core so much more accurately than is usual as greatly to improve the quality of the castings. Incidentally, the

practice ojtithis new process and the employment of thenew retainer device permits a substantial reduction in the number of the chapletsemployed, since the reinforced grecn sand prints,furnish so rigid a support for the core that but little further support is necessary. in the number of chaplets required is sufficient to ofl set the cost of thenew-reintorce device.

In the accompanying;drawings I have illustrated-certain steps in my improved process as applied h way of example to the productionot a radiator section and have also illustrated by improved reinforce Fig.6 is an elevation, partly in vertical. scctionand partly broken away of a radar,

torsection as itappears when removed from the mold;

Figzt is a 1' .iginentary section of a easting made-in accordance with the present invention and i illustrating the step of machining the opening therein;

Fig. 7 is a tragn'ientary vertical section illustrating a usual lnodefot connecting a pair of radiator sections; and

Fig. 8 is a. if'aginentary vertical section through a mold, showing the casting therein and illustrating the results of using a core printr Referring to the drawings, the numeral 1 designates a pattern, herein illustrated as that for making ani ordinary ra tliator section such as is used in inaking huilt-up radi a tors for steam or hot-Waterheating. The pattern is shown as restii'i r upon -a plate or hottom hoard i2, uponavhich is placed-one inenil'ier 3 ol a two-part umlding-llask.

\Vhile it is immaterialWhether this he con-- sidered as the bottom or top meinher ol: the 'tlafsltait is for convenience hereinafter referred to asthe hottoin ineinheri- In accordance with the present inventionthe pattern-1 isiprovided atsuitahlc points with cavitieset, each of the desireddiameter and dept-lito receive a portionol? thenolih in'g: sand to lorm ;a green sand print, Such printa produce opeiiings in dhewasting, and in the manufacture ofradiator sectlons-itns desirable togproduce'an; open ng at hoth ends o'lf-tlie--sect-ion aml atmzch side o-lihe In many Lcases the.Jcduetion latterito receive the llllltlllllil or other device cn'iployed tor uniting adjacent sections.

In accordance with the present invention, hetore-einlicddii if the pattern in sand, l: in troduce a print reinforcing; device into each of the cavities -:l. llteitcrrin to lii s. I} and -.l, I illustrate a preferred term of such rehe force device. As herein illustrated this rcinl orcedevice [I is a cup-lilie structure, pre i erahly tapering FY0111 one end to the other, androinprising a generally (j/illitll'ltftll wall portion 7 preferably having at its smaller end an inwardly directed annular flange and having anchoring tabs 9 projecting from its'uppcr end. its hereslmwn, toun such tabs are provided, hut-the exact numher is immaterial. i

Preferably this reinforce device made i a stamping operation (ll'Olll SllQQll inatcrial and in order to ju'ovidc the nece sary depth of cupI prefer to slit the material as indicated at10, although I contemplalo that it tlieniaterial, heo't' suliioient ductility such slittin inav he dispensed with.

I also pro. .1' to employ perforatedimate rial in making this retainer, sineesuch per-i iterated material possesses sutlicient Htlll Ilu-ls for the puiposeu'hile at the same time it contains much less material thanit made of inuiertor'ate sheet nuderial. Thus it has less tendency to cool and sin'lace harden i llainolten iron which comes into coiitact there with. While-,-as just stated, the. rot-liner may heniade of perforated sheet metal, ll contemplatethatit might he made from a sheet-or \vire inesh i'naterial andfll. also rontemplate that -1naterial other than metal a l a lie en'iployed to advantageunder some cii" cui'nstances.

The-retainer is prel erahly of, such dimensions and shape as to litsnugly .u'ithin the oi'ienings oftho pattern, thus termin in.

effect a lining tor the o lieniu r. the lower edge -12 oi the retaii'ierseating uponwthc bottom otthe opening, vhile the uppec value 11 of the retainer is suhstantiallv flush with the upper edge ot the opening. Tlheamolmring tal s D projecbahove .the top ot the openings so that they are .lirinlv embedded in the sand 13 \Yil'lt'it is now rzunuuul llll During this lumping ol" thewand.

the flash. it is quite prohalrlc that the anchorincur hers 9 are deflected outu'ardl to some (K- upon the main hodv oi? the .sa 11d Within the completely tilled with compacted sand. porprint *as completedyeonsistsc-o't small sew tions ol sand i embedded iin the sul'iatanco ot', the: retainer deviee.

When-the flaski hasi been. tilled: a nd .propen ly tamped, the section *isfuim'ei'tcd and tent so that the ohtain a 'vcrv ilirui :ui i

tions i of which enter the perforations o t' the. retainer, so that the. outer surl'aeeool' the separated from the board 2 and the pattern 1 is withdrawn'trom the sand, thus leaving the mold cavity 15. The green sand prints tor-med by the above operation now project into the mold cavity, such prints being retained in proper position by the retainer devices 6 which in efi'ect form still and tough outer shells or skins for the prints.

In a similar way the upper section 3 of the flask is provided with a mold cavity 15 also having the green sand prints projecting from its wall, such prints being reinforced by retainers in the manner just described.

A core ll) of suitable shape is made in the usual manner, such core being provided atthe proper points with shallow socket openings 16 corresponding in number and position to the prints provided as above described. The niolder now takes this core and sets its lower socket openings 16 over the inner ends of the reinforced green sand prints projecting up into the lower half 15 of the mold cavity. It necessary. chaplets l7 and 17" of any desired type may be introduced at the proper time in the operation to provide additional supports for the core.

The molder now disposes the inverted upper half of the flask upon the lower half in such manner as to cause the reinforced green sand prints which project from the inner surface of the upper mold cavity 15 to register with the socket openings 16 at the upper side of the core.

As above stated such shallow socket openings 1h maintain their accuracy of shape and position after baking much better than does the usual core print. Since the core is quite stiff, as are also the reinforced prints, these sockets may be relied upon as a means for locating the core.

in accordance with the present invention the green sand prints having the stifl' and rigid outer skins or shells are capable of withstanding lateral pressure without breaking down or deformation and thus when the sockets ot the core member receive these reinforced prints the core is held very rigidly in position so that it can not move in a lonaiiudina] direction or toward or from the lateral wall of the mold cavity. This rigid support of the core is such and the accuracy of location is so superior to ordinary practice that I find it possible to reduce the thickness of the walls of the castings produced by this process, thus saving a considcrable amount of material without unnecessarily sacrificing strength in the finished casting.

The mold, having been completed as just described, the iron is poured in the usual manner, producing a cored casting such as indicated at 19 in Fig. 5. When the casting is removed from the mold the retainer devices 6 are found to be united to the casting and project from the latter as indicated in Fig. 5. Since the taper of green sand prints, made as just described, is inwardly of the casting, it may be noted that the opening in the casting tapers inwardly as shown at 21, the: retainer device constituting a lining for this opening.

T he opening may now be finished and the retainer removed as indicated in Fig. 6 by introducing a tapered milling cutter 22 or other proper tool which cuts out the retainer device and produces a smoothly finished inwardly tapering opening. As the opening in the casting, defined by the retainer device, tapers inwardly, the amount of metal to be removed by the machining operation is very small as compared with that which would necessarily have to be removed were the o icning made initially with its taper in the opposite direction. Moreover since the retainer device constitutes a lining for the opening. the cutting tool does not encounter hard particles of slag, embedded sand, or the like. and retains its edge much longer than when used in an unlined opening, it being obvious thatundcr some circumstances the presence of this relatively smooth and finished lining element may render machining wholly unnecessary.

In Fig. 8 I have illustrated the result of employing a core print, the main body of the core being indicated at O and the print at P. The molding sand is indicated at S and the casting at I. In this case it may be noted that the opening produced in the casting flares inwardly. To produce an inwardly tapering opening in such a casting would thus require an excess amount of ma chine work.

After the casting has been machined in the manner illust 'ated in Fig. 6 it may be associated with a similar casting 19" as indicated in Fig. 7 and united thereto by a thim-ble 23 having oppositely tapered portions 21 and 21, this method of uniting the sections and the means for connecting them being old and well known and forming no part of the present invention.

\Vhile I have illustrated the invention as applied to the melding of: a radiator section, it is to be understood that the invention is not confinedto this particular use or environment but that it may be found use ful in the production of any cored casting in which an opening is to be provided during the process of casting. Furthermore, in so far as the retainer device is concerned, it is clear that the dimensions and exactshape here shown are not in any sense to be considered as limiting since such retainer will be made to conform. in any particular case to the shape and size of the desired print. Moreover, I contemplate that under certain circumstances the retainer may form less than a complete circle; that it need not form the outer snr'face of the print but may be embedded more deeply therein than hereinabove described; and that in fact the reinforcing of the green sand print may be accomplished broadly speaking, in other ways and by the use of other materials than those hercinabove referred to.

I claim:

I. That process of making molds for cored radiator sections which comprise preparing a pattern having spaced print forming cavities, placing: reinforce material in each cavity, embedding the pattern in sand, removinnthe pattern to leave a mold cavity hav ing spaced reil'il'orccd green sand prints projecting into it, preparing a core having spaced print receiving sockets, and locating the core in the mold cavity by .litti-nP; its socket-s over {he re-pcctive prints.

That process of making molds for cored radiator scctione which comprises forming; a mold cavity having a. plurality of rspaced sti if and rigid reinii'orced green sand printn projecting into it, providing a core having sockets; spaced eimilarl to i-aid prints, and locating thecore in the mold cavity by fitting its respective sockets over corresponding prints.

That process olfmaking molds for cored castings which comprises as steps providing a pattern with an inwardly tapered print forming cavity, lining eaid cavity with reinlorce material, permitting a portion of said material to project beyond the cavity, cm-, bedding the pattern in sand, ren'ioving the pattern to leave a mold cavity in the sand with a tapered reimlerced green eand print projecting inwardly into the cavity, and engaging a core with the inner end of said print.

4:. A print reinforce device comprising a thin walled shell TlO'l' encloi'iing the sand of a green sandprint, said shell being, of openivorlc construction so that the enter riacc of the completed print coaf ta of email sections of sand embedded in the nnhntancc of the retainer device.

A cup-like retainer of perforated sheet metal for preserving the shape oi. a green sand print, said retainer lacing provided at one end with anchoring means.

6. A device :lor preeerving the shape oil a green sand print comprieiinr a thin walled shell for reinforcing the eiqiioaed isnrlaccr ol the print, and means or anchoring the device in position.

i. A reinforce device r leei z'nc l to Form an outer skin for a green rand print. said device conipriein g a cylindrical Willi portion provided with an inwardi; directed llange atone end adapted to prevent the sand from dropping out of the end of the r:-inl'orco device.

A printing reinjl orce device compriain r a thin metallic :ihell having, a cylindrical wall provided with an inwardly directed radial flange at one end and with anchrn'ing means at its other end.

9. reprinting; reinforce derive comprteinp a. tapered cyliinlrical ahcll oi ahcet liltlll'l'llll having a plurality ol. anchoring lair: preparime from its larger end.

ll). Apr-int reinforce device comprising a. tapered cup-like shell oil perforated ahcci. material, Said shell having an amnilar inwardly directed flange at il'i smaller vial and a plurality of circmnllercntially Spaced anchoringtabs at its: larger end.

Signed by me at lVestlield, lilasaachneclta, this 30th day of September, 1926.

CLARENCE it. re ace.

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