US2303092A - Method of preparing metal molds - Google Patents

Description

l-1 w.24,1942.; w L RAPHAEL 2,303,092

METHOD OF PREPARING METAL MOLDS Filed Aug. 4, 1941 2 Sheets-Sheet 2 la 02u/ @J2 f N yf www v azaa Patented Nov. 24, 1942 METHOD 0F PREPARING METAL MOLDS yWalter J. Raphael, Los Angeles, Calif., assignor of one-half to Robert Neuschotz, Los Angeles,

Calif.

Appucation August 4, 1941, ser1a1N0.405,317

. 9 Claims.

This invention relates to a method of preparing metal molds used for producing castings.

Heretofore metal molds have usually been produced by shaping the mold cavity in the sections of the mold by routing or milling out the` mold cavity in a block of metal that forms a part of the mold. Such procedure usually requires considerable labor of a highly skilled type and in` volves the expenditure of a great amount of time. Sometimes the block of metal from which the mold section is to be formed is cast to approximate shape and then finished by routing or milling out the mold cavity to the desired formation.

An object of the present invention is to provide a new method for constructing the sections of a l' metal mold whereby the parts of the mold can be easily shaped to conform to the shape of the pattern or the casting that is to be produced.

More specifically, an object of the invention is to provide a method of preparing metal molds wherein the mold sections are produced byspraying molten metal around a pattern so as to coat the pattern with metal conforming on its interior to the pattern shape. It has long been desirable to be able to produce metal molds by spraying molten metal around a pattern, but heretofore attempts made in this direction have proven unsuccessful due to the fact that the sprayed-on metal either does not closely adhere to the pattern or it warps on cooling so that the mold sections do not accurately conform to the pattern shape because of YWarpage.

It is, therefore, another object of the invention to provide a method Yof producing metal molds by spraying molten metal over and around a pattern Awherein the sprayed-on metal will be caused to .closely adhere to the pattern so as to 4accurately conform to the pattern shape and tive pattern being employed to produce a positivepattern half which is employed in the construction of the mold in accordance with the present process:

Fig. 3 is a sectional view illustrating the assembly of two positive pattern halves preparatory to the application of sprayed-on molten metal;

Fig. 4.is 4a sectional view illustrating the positive pattern halves as having been coated with metal applied thereto by spraying;

Fig. 5 is a partial view in vertical section illustrating the details of the construction of the fastening studs or inserts which are attached to the positive pattern and which become parts of the mold sections providing for their attachment to a suitable machineA for supporting the mold sections;

Fig. 6 is a partial view in vertical section illustrating the manner in which the mold is divided or separated into its sections;

Fig. 7 is a partial view in vertical section illustrating a separated lower portion of the mold;

Fig. 8 is a View in side elevation of the completed I nold, the sections of thel mold being illustrated in abutting relationship; A

Fig. 9 is a vertical section through a mold made in accordance with the present invention but illustrating the mold as having been slightly modified-so as to receive a core;

Fig. 10 is a view in front elevation of a machine illustrating the mold made in accordance withr the present invention as having been installed 'tion of the machine illustrated in Fig. 10, the

positions capable of being assumed by the linkage connection being illustrated in full andin dotted lines.

Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, I0 indicates an original half of a pattern of the casting that is to be produced. This pattern may be of any desired configuration or shape and may be formed of wood, plaster, plastic, or other material conventionally employed for this purpose. In accordance with conventional pattern making practices the original pattern is divided usually into halves the upper half being illustrated at IIJ and the bottom surface thereof being arranged on a. plane that is to be coincident with the parting plane or parting surfaces of the mold.

The pattern l0 not only conforms to one-half or one portion of the finished casting but preferably has 4formed thereon a pattern portion Il that is to provide the gate for the mold. If risers are to be present in the mold riser patterns are also formed on the upper pattern half Il) in a similar manner to the gate pattern portion Il, The pattern section, the gates, and

-4 relationship asv illustrated in Fig. 3;

risers are au shaped with draft in the 'conventional manner.

The pattern I! is positioned on a spacer pattern I2 which may consist of a flat plate or flat board or a plate whose surfaces' conform to the parting lineof the casting to `be made which preferably projects outwardly beyond all portions of.the pattern half III. The spacer pattern I2 rests upon'a suitable supporting suri' face or -table I3. A flask I4 is positioned on the supporting surface I3 to surround the pattern half I and the spacer pattern I2. The pattern IU and spacer pattern I2 are coated with oil or stearic acid or other separating material and the flask is then filled with a self-hardening plastic material I5 which may be a rubber producing a negative pattern I8 as illustratedin Fig. 2. The interior of this negative pattern is then coated with oil, stearic acid, or other 25 'separating medium, and a positive pattern I'I is produced thereinby filling the cavity in the negative pattern with a self-hardening plastic material which may or may not be oi' the same character as that employed to make the negative pattern Il. The positive pattern I'I con forms in shape to the original pattern half III except that there is integral Atherewith a spac' ing portion I8 equal in thickness and of the same size and shape as the spacing pattern I2.

In Figs. 1 and 2, I have illustrated .the construction of the positive pattern I1 ,correspond- -ing to the upper half ID of the original pat-l tern, it being understood that the upper halfof a the equivalent which will -resist deterioration the original pattern is usually that which carries with it the' gate or riser patternportions. v

portions of thefastening stud elements 20 and II. The lower half' oi' the original pattern, not

shown,`is likewise employed to make a negativeVA pattern corresponding to lnegative pattern .I8 f

.45 metal is applied thereto as indicated at 3l. This and from this negative pattern af positive pattern Il is-produced in a similar manner.

When these positive pattern halves are produced they are .assembled together in abutting Their spacer portions I8 are apertured at suitable locations and fastening studs are applied thereto, the details of which are illustrated in Fig. 5.

The fastening studs comprise male and female parts 20 and 2i, respectively, the male part a,sos,oaa

therethrough for the reception' of ejector, rods 3l, see Fig. 10. With the positive mold thus con'- structed as illustrated in Fig'. 3, those portions of the .mold that are to be coated with sprayed-. on metal are rst coated with a composition that will tendto cause the sprayed-on metal to firmly adhere to the positive mold. I find that for this purposeone such composition that may be emv ployed consists of one to two parts of flowers of 1o sulphur and eighty parts of iron filings with sufficient water added to render the mixture a thin paste or paint that 4can be brushed on to the surfaces of the positive pattern that are to be i sprayed with molten metal. Another composition that may be employed consists of ten parts of iron filings and three parts chloride of lime lwith sufiicient water added to render the mix-f 'ture a .thin paste or paint that can be brushed onto the positive pattern. In some instances the composition may be mixed with the plaster that forms the positive pattern, or if desired, the en-V tire positivepatternmay be cast of said composition.

vIf the lpositive pattern is made of plaster of Paris it is'desirable to thoroughly dry the posis tive pattern following its production. This may be dried in a baking oven or may be air dried if vsuiiicient time is permissible for this method of drying. The application of the coating which tends to cause the sprayed-on metal to adhere to the pattern may take place before or after the drying of the pattern but if the coating is applied after the drying of thev pattern it likewise should be dried before metal is sprayed onto the pattern. 'I'hose portions of the pattern that .are not to be coated with the sprayed-on metal are masked. In other words, the projecting portions ofthe ins/erts 29 may be masked such as by cementing or tie' wiring on asbestos sheet or under the sprayed-on metal. The projecting 2I are similarlyv protected by masking.

With the pattern thus completed a coating of Yso as to completely cover the lpositive patternl being applied to al1 exposed surfaces thereof and around the inserts 29 and around the bases or roughened portions 28 of the fastening studs' 20 and 2I. When the coating of metal 3| is applied entirely around the positive pattern 'it 20 having a pilot 22 receivable in a socket 23` 55 Will be fOllIld that any tendency 0f Wal'pge 0r in the female part 2I. The pilot 22 extends through the apertures formed in the projecting portions of the spacer portions I8 of the positive pattern halves and is internally threaded to receive a bolt 24 which fastens the parts to'- gether and thus hold the positive pattern halves in abutting relationship. The outer ends of the fastening studs are'internally threaded as at 25 to provide for attachment to vertically movable mold section holders 26 and l2'I as illustrated'in Fig, 10. Each fastening stud adjacent its inner end is externally roughened as at 28 so that the for the coating to pull away from the positive pattern is eiectively eliminated. If.the external surface of the positive pattern has concavities I nd that the coating applied to the pattern tends to cause the sprayed-on metal toilrmly adhere .to the positive pattern even in the concavities so that there is no tendency for the sprayed-on metal to shrink or retract from the concavities in the pattern. When the positive pattern'sections have been completely coated with the sprayedon metal the metal is then normalized to relieve all strains that may be developed dur- -ing the spraying operation. This normalizing is usually done by heating the metal to approximately 1100 F. and then permitting it to slowly coolsuch as in a bed of lime.

When this step is completed the mold has the appearance as illustrated in Fig. 4, following which the edges of the mold surrounding the through the walls of the mold which forms holes spacer portions I8 are removed as illustrated in l desired in thebody portions of the mold sections `these may becut or drilled therein.

\ i a,sos,ooa

. tenminuneouny separate. wnen-the'opersnng Fig. 6. The removal of these edge portions may be accomplished by grinding or cutting. If the metal has been applied over thel gate or riser portions li of the positive pattern-this metal is also removed so as to open the entrances to the l gates and risers. Thus, by the removal of the edge portions the mold is divided into upper and lower sections constituting the cope and the drag of the mold. They may then be separated from eachother and the positive pattern removed therefrom. Those portions of the mold sections that were formed by the spacer portions I8 provide the parting surfaces of the mold sections 'and when the mold sections are assembled together in abutting relationship as illustrated in Fig. 8, the cavities in the mold sections will lthen each accurately conform to the halves of the original pattern. If it is desired to vent the mold, small grooves may be cut or ground in the parting surfaces as illustrated at' 32, and if vent holes are The thickness oi' the metal coating S may vary. However, for .ordinary purposes this need not exceed one-quarter or three-eighths inch.- The metal used for the coating may likewise vary depending upon the nature of the material Vthat is to -be cast. .For example, if the casting is to be of aluminum. the initial spraying of the positive pattern maybe performed with a chromium steel .alloy and the balance of the coating 3| may be formed of low cost. low carbonv steel so that the chromium steel alloy which forms `a facing on the interior of the mold cavity will edectively re-v sist any pitting eil'ect lof the molten aluminum.

T he `coating 3l need not be formed. however, of a.

ferrous material. Bronze or other metals may be substitutedl therefor -if desired, depending upon the nature of the material .that is to form the casting. 1

In the event that the casting .that is-tobe produced is to be cored, the pattern i is equipped divided into two parts 'but patterns divided into additional parts maybe used if desired. The na .ture ofthe mold and pattern. to some extent will link I2 is inthe vertical 'position or full line posi tion themold sections are brought into 'abutting relationship in which position the molten material that is to be cast-'may be poured into the mold through the gate.- The ends of theejector rods "which are exposed on the interior of the mold chill the casting in' the localities of their' ends, and when the mold sections are separated" they slide upwardly and downwardly respectively on these ejector rods so that when the molten material has been poured into the mold to form the casting and the mold sections are separated -the ejector rods serve to support the casting between the separated mold sections; Thereafter,

set in ahorizontal plane. This type of machine is edaptedto be used thereon, moms having para l ing planes and gates or risers in a vertical plane 'rather than in the horizontal plane illustrated.

It v'will -also be understood that in making the .mold in accordance with .the present .invention j v that 'it is not restricted to the use of patterns..

affect the type of machine used, that is whether the mold will be mounted on a machine which separates the mold vertically as shown, or hori4 zontally. f-

While itis advantageous to employ a coating on the positive pattern to cause the sprayed-oni- 'metal to adhere `to the surfaces of the pattern with core prints which define portions vof the mold indicated at 33 to Yreceive portionsof the core illustrated at 3l so that the core which may be a sand core or heat resistant plaster, is properly supported within 'the closed mold. Where the shape of the core permits, metal cores may be used in the conventional way. j

' With the mold thus completed it may be mounted within any suitable holder or a casting.

- machine such as that illustrated in Fig. 10,

whereinthe lower moldsection is fastened by means of its fastening studs to the lower holder 21 and the upper mold section is fastened' by those fastening studsto the upper vholder 26. These holders are movable toward and away from each other upon suitable vertical guides 35: Elector rods 30 are suitably mounted on supports 36 and 31 and extend into the openings in the mold walls formed by the inserts 29, or holes which may have been drilled for the purpose. Thev lower ejector support 3l is vertically movable by means of links 'which connect it to an eccentric shaft 38. The upper mold support V2li is connected by means of links 39 and 40 to thetop of the machine. Links 4l connect the pivotal connection between links 3S and 40 to an operating link 42. Similarly, the lower mold support is connected by means of links 43 and M to the bottom of the machine and links 45 connect the pivotal connection between these links to the operating link I2.

As illustrated in Fig. 11, when the opera-ting link the pattern. I dnd that if the lis not applied entirely -around the pattern the warpage of the metal on cooling' brings about distortion so that-the m'olddoes not conform to-the'f,v pattern. In some instances. the sprayed-'on need .not completely Isux'rotuid the pro' vided that. it sufficiently" overlaps 'an exposed l "side, but under these circumstances of composition'previousl! unna-:munitie: accuses', tofirmlyadheretothe-padtivepat in some instances this coating may be omitted, i particularly where the is. small, provided. that the sprayed-on metal completely surrounds sprayed-on metal ment of the coating referred to ishishly the metal tern.'

-While itis possible.to?dispense''vritlifn'lak'ing a negativev pattern yand a Apositive pattern therefrom, and instead use the original pattern .is and the spacer-pattern-l l2 in place of the positive pattern I1, Iprei'er positive patterns so that if difilcnlty' is experienced in removing *the positive pattern from the completed mold the original pattern is in no way.

defaced or mutilated- In some instances the ,to make the negative and making of the original pattern and 'theproduction of a negative pattern therefrom. can vbe dispensed with. The negative pattern may be made as the original pattern and a positive pattern or print may be obtained directly therefrom. It is also possible to make the positive pattern sections not integral with the spacer I l. Thus positive pattern sections can be produced conforming in shape to the original pattern sections and thesapattern sections may then be cemented, to s aepjarate spacer with silicate of soda or thelik'e. I. -f it will tbe,.-

. .From the above-described appreciated that s'novel, simple; and advantage."

l2 is swung from the full line position to the eusmenwd er prepari mem/meuh nu provided which of' routing or milling out the shape of the casting in the mold. Molds produced in this manner can be caused to accurately conform in shape to that of the original pattern I0.

Various changes may be made in the details of construction without departing from the spirit or scope of the invention as dened by the appended claims.

I claim:

1. The method of making metal molds having partingskt'vhicii includes applying pattern sections to the sides of spacer patterns, which sides are to define parting surfaces of the mold, forming negative patterns from the pattern sections and spacer patterns producing positive patterns from the negative patterns, positioning the positive patterns in opposition with their spacer portions disposed together, coating the positive patterns with metal, dividing the mold around the spacer portion, and removing the metal that projects beyond the parting surfaces of the mold sections defined by the spacer portions. I

2. The method of making molds which includes incorporating in the surfaces of positive pattern sections a material containing metal filings which will cause sprayed-on metal to firmly adhere to the surfaces of said sections, and spraying the sections with molten metal.

3. The method of making molds which includes incorporating in the surfaces of positive pattern sections a material containing metal filings which will cause sprayed-on metal to firmly adhere to the surfaces of said sections, assembling said sections in spaced relationship, spraying metal over the sections and over the intervening space therebetween, and removing the metal between the pattern sections.

4. The method of making molds which includes incorporating in the surfaces of positive pattern sections a material containing metal filings which will cause sprayed-on metal to firmly adhere tov the surfaces of said sections, assembling said sections in spaced relationship, spraying metal over the sections and over the intervening space therebetween, normalizing the sprayed-on metal, and removing the metal between the pattern sections.

5. The method of making molds which includes assembling in spaced relationship positive pattern sections on which metal may be sprayed, ap-

plying to said sections holding or supporting inserts, masking protruding portions of the supporting inserts, and spraying metal over the positive pattern sections and across the space therebetween, and finally removing the metal between the pattern sections leaving exposed portions of the inserts embedded in the sprayed-on metal.

6. The method of making molds which includes applying to the surfaces of positive pattern sections a material containing iron filings which will cause sprayed-on metal to firmly adhere to the surfaces of said sections, and spraying the sections with molten metal.

'7. The method of making molds which includes applying to the surfaces of positive pattern sections a material composed mainly of iron filings and a small amount of fiowers of sulphur to cause sprayed-on metal to firmly adhere to the surfaces of said sections, and spraying the sections with molten metal.

8. The method of making molds which includes applying to the surfaces of pattern sections amaterial composed mainly of iron filings and a small amount of chloride of lime which will cause sprayed-on metal to firmly adhere to the surfaces of said sections, and spraying the sections with -molten metal.

9. The method of making molds which includes incorporating in the material from which a pattern is made iron filings so that the iron filings on the surface of the pattern will cause sprayedon metal to firmly adhere to the surfaces of the pattern, and spraying the sections with molten metal.

WALTER J. RAPHAEL.

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