US1731060A - Method of forming metal castings of metals of different hardness and contractive properties - Google Patents

Description

d- 9 c. E. REINHARDT 6 IETHOD 0F FORIIING METAL CASTINGS 0F METALS OF DIFFERENT mummass AND CONTRACTIVE PROPERTIES Original Filed Dec. 22, 1925 2 Sheets-Sheet l INVENTOR. E. Reinhardt fl /ITTORNEW Qerr BY 1929- c. E. REINHARDT' 1,731,060

METHOD OF FORMING IETAL CASTINGS OF METALS OF DIFFERENT HARDNESS AND CONTRACTIVE PROPERTIES Original Filed Dec. 22. 1925 2 Sheets-Sheet 2 C IIG/VIHNTOR.

-errol E. Rein r t BY QW Z2 ATTORNEYS patented Oct. 8, 1929 LIN l .1 9 STATES CERROL E. REINHARDT, 0F MONTREAL, QUEBEC, CANADA METHOD OF FORMING METAL CASTINGS OF METALS OF DIFFERENT HARDNES S AND CONTRACTIVE PROPERTIES Application filed December 22, 1925, Serial No. 76,960. Renewed March 5, 1929.

My invention relates to a method of making castings composed of two or more metals having different contractive properties and uniting them together, either by shrinking one metal upon the other or by uniting them by fusion during their solidiiication in a rigid mold containing them. With methods hitherto employed, a casting composed of two metals of different contractive properties, could not be cast and permanently united during solidification, for if the metal of greater contractiveness surrounded the metal of lesser contractiveness, the latter caused an obstruction to the natural shrinkage and contract-ion of the outer metal having greater contractive properties, causing cracks, flaws or undue internal stress to develop therein during the solidilication of the casting. While on the other hand, if the metal of lesser contractiveness, surrounded the metal of greater contractiveness, the interior metal after once setting would shrink away from the outer metal of lesser contractiveness, thereby preventing serviceable unity of the two.

The new method described herein, consists in pouring the metals into a rigid mold, containing a. plate adapted to separate them, the said plate being preferably of such thickness that the molten metals when poured will either cause the plate to melt as the metals surrounding it solidify, or heat the plate sufficiently to cause it to fuse with both metals. Before either metal has solidified, pressure is applied to both metals and the plate separating them over such areas Wlll keep both solidifying metals pressed tightly against the separation plate and s1multaneously prevent the development of tensile stress in either of the metals cast. The said pressure being supplied until all parts thereof that are obstructed from normally shrinking have become substantially solid and in sufficient amount as to keep all particles of both the metals cast in contact substantially throughout solidification.

The method may be applied to the manufacture of various kinds of composite castings that require greater strength or hardness at some portion thereof, including,

gear wheels and the like. Further and more sp ecific objects, features and advantages will more clearly appear from the detailed description given below taken in connection with the accompanying drawings which form a part of this specification and which illustrate the application of the invention to car Wheels and from which those skilled in the art will readily understand the applicability of the invention in the making of other kinds and forms of composite castings.

In the accompanying drawings- Fig. 1 is an elevational view of the wheelmold and pouring ladles;

Fig. 2 is a vertical section of the mold and press when pressure is about to be applied; and

Fig. 3 of the mold and wheel after pressure has been applied.

Referring to the accompanying drawings by corresponding reference characters throughout, the numeral 8 indicates in general a mold comprising a cope-section 9 and drag-section 10, in which an annular separation plate 12 is positioned to divide the rim of the wheel into two separate and distinct parts. A refractory core 13 hollowed to form a gate 14:, is set into the drag-section 10 and a second refractory gate 15 is located in the box like extension of the drag-section 10. The cope-section 9, which contains a movable pressure ring 11 and vent holes 19 is set upon the drag-section to form the mold 8, the pressure ring resting upon the annular separation plate 12. Gate cutters 17 and 18 are positioned so that when they are caused to move downwardly they will cut off and seal the gates 14 and 15.

With the mold thus assembled, the ladles 20 and 21, suspended from the stub shafts 22 are brought into position, the ladles being actuated by means of hand wheels 23 operated by gear wheels 24 that act upon geartoothed racks 25 and tip or rock as desired to pour the metal contained in the ladles into the gates 14 and 15.

Preferably a molten alloy steel is poured from the ladle 20 into the gate 15, while at substantially the same time molten mild steel is poured from the ladle 21 into the gate 1%, gases in both parts of the mold escaping through the vents 19. As the two difierent metals fill the mold matrix on opposite faces of the separation plate 12, they heat the said plate rapidly and cause it to fuse with them both, for the separation plate 12 should be composed of a proper fusible metal of such thickness that it will melt or fuse when molten metal is applied to both of its faces, but which will not melt through when the metal is applied to but one side thereof.

Directly after both parts of the mold matrix have been filled with each of the different metals, it slid onto a press 26, the gate cutter 18 making contact in passing with a lug 2?, causing the gate 14 to be sealed. As soon as the said mold is centered on the bed of the press and before the solidification of either metal contained in the mold is complete, the press ram 28 is forced downward by hydraulic pressure and makes contact with the gate cutter 17 so that it seals the gate 15 before making contact with the pressure ring 11. As the press ram :28 forces the pressure ring 11 into the mold the vent holes 19 are automatically closed and pressure is transmitted. to both solidifying metals in the rim of the wheel as well as to the separation plate 12.

The application of pressure, thus directed L w 1 1 to 136th illCoiLb 1.) cominuec as SOrlC1 cation proceeds, and is of such value as to decrease the volume of both metals forming the rim by an amount substantially equal to or greater than the decrease in volume caused by natural contraction during solidification, such pressure being continued until the metal of greater contractive property has become sufficiently solid to develop sufiicient strength and elasticity to withstand the strains created by any further contraction in cooling without cracking or developing undue internal stress after the release of pressure application.

As the metals in the matrix of the mold solidify and contract after the sealing of the rent holes 19, the continued application of pressure forces the pressure ring 11 farther and farther into the mold matrix holding botl metals in constant contact with the separation plate 12 as solidification proceeds. in this instance, as the inner metal forming the hub and plate of the wheel is of lesser contractivc property than the outer metal formthe tread of the wheel, the inner metal through natural causes obstructs the normal shrinkage of the outer metal which contracts more ra idly due to possessing greater contractive m'operties. To prevent cracks or undue internal stress that would ordinarily be cau ed by such obstruction to normal shrinkage and contraction, pressure is ap plied to the metal of greater contractive prop erty upon all obstructed parts during solidification to cause to flow as solidification and contraction proceed, causing its shrinkage in certain directions to conform with that of the In al of lesser contractive property. This ion of shrinkage during solidificaurther simplified by the fact that press ire must also be applied to that part e metal of lesser contractiveness that is the metal of greater contractiveness shape of the mold matrix is such that e rim of the wheel is obstructed mally shrinking and contracting. in making car wheels it is not absolutely c r t the annular separation plate tel or to either of the metals, its main tron being to prevent the metals from with each other for the outer or sur- L, 7

i on ding metal could be made sufficiently to possess suliicient strength with merely sarink-on fit and no fusion to either the annular plate or metal wheel center it surrounds and binds upon.

A modification of the invention lies in the casting of a composite metal article upon a solid metal article that is to become an ini part of the finished product, for ena composite steel tire, comprising orm a steel-tired wheel as a finished product. as in the manufacture of composite wheels, heretofore described, a metal separation plate is placed within a rigid mold which surrounds a non-collapsible wheel center of less diameter and upon which the mold closes tightly. This leaves a mold matrix between the said wheel center and separation plate as well as a separate mold matrix surrounding the said separzn 1 plate. The mold is then filled with molten metal of different hardness and contractive properties on both sides of the separation plate, and pressure is then applied substantially throughout solidification to all parts surrounding the non-collapsible wheel center, including the separation plate, to preven the development of tensile stress due to shrin .age and contraction. This produces a sounc, composite metal tire on a solid and non-co center, which subsepsible wheel quentiy upon cooling becomes an integral part thereof.

in applying this invention to articles where the metal of lesser contractiveness would surround the metal of greater contractiveness, it is preferable to apply pressure to both metals as they solidify, but in any case the pressure mus be applied to the metal of greater contractiveness, in order to cause flow and force it outwardly so as to maintain contact with the metal of lesser contractive proper ties, pressure also being applied upon all parts of the casting where shrinkage is obstructed by the mold matrix throughout the c': of diiferent hardness, applied in solidification of such obstructed parts. The pressure should be applied as the metals cast in the mold pass through the plastic, pasty and granular states in sufficient amount to cause the metals to flow during the latter 7 stages of solidification to prevent the formation of cracks or undue internal stress in the casting.

lVith the use of my improvement smooth, sound metal products of two or more metals may be produced in various shapes and forms at a much lower cost by the use of a battery of molds and proper machinery for feeding them onto the press that would make for continuity of production; also a great variety of metals of different hardness or contractive properties could thus be made into serviceable products, as it is not essential in many articles that a positive bond or Weld be effected. Many other applications of the invention will therefore be apparent to those skilled in the art.

While I have described my improvements I in detail connection with one form and application thereof, I do not desire to belimited to such details and forms since my invention may be embodied in widely different forms.

Vv hat I claim as new and desire to protect by Letters Patent, is:

1. The method of forming composite castings in rigid molds having obstructions to natural contraction, which consists in pouring two metals of different hardness and contractive properties into a rigid mold containing a plate adapted to separate them, and applying pressure simultaneously to both metals and the said plate, causing the metal of greater contractive property to follow the shrinkage of the metal of less contractiveness.

2. The method of forming composite metal products which consists in pouring two metals in a rigid mold containing a plate adapted to scparate them and also a non-collapsible object intended to form an integral part of the finished product, and after substantially sealing the mold, applying pressure to those parts of the poured metal during solidification where tensile stress would ordinarily be developed in the cooling of the metal, said pressure being sufficient to cause sufficient metal to flow into all regions which cannot freely shrink or contract to prevent the formation of cracks and fractures in eitherof the metals cast.

3. The herein described method of forming composite castings which consists in pouring two metals of different contractive properties into a rigid mold containing a plate which entirely surrounds the metal possessing the lesser contractive property and which is entirely surrounded by the metal possessing the greater contractive property,,and after substantially sealing the mold, applying pressure simultaneouslyto the outer metal and to that part of the inner one which cannot freely contract and also to the edge of said plate whereby to cause the metal of greater contractive property to follow the shrinkage of the metal of less contractiveness.

4. The method of forming a car wheel com posed of two metals of different contractive properties which consists insimultaneously pouring the two metals into a wheel mold containing a fusible annulus dividing the outer portion of the rim from the remainder of the wheel, one of the metals being poured internally of the annulus and the other externally thereof, whereby the annulus fuses with and unites the two metals, and applying pressure to the entire rim portion of the wheel in sufficient amount to force the metals to remain in constant contact with said annulus and also to equalize the final contraction of the said metals during solidification.

5. The method of forming car wheels comprising a soft metal center entirely surrounded by a hard metal tire, which consists in pouring two metals at substantially the same time into a mold containing an annulus dividing the rim of the wheel into two parts and possessing the property of fusing to both of said metals, and after substantially sealing the mold, applying pressure directly to both metals at the rim portion of the wheel to force both of the metals to remain in contact with the annulus until substantially the entire rim is solidified, and also to compress said rim as an entirety in one direction and tend to elongate it as the metal contracts during solidification. I

6. The method of forming composite castings composed of two metals of different contractive properties in rigid molds having obstruction to the normal shrinkage and contraction of the casting, which consists in pouring two metals into a rigid mold containing a plate adapted to separate them in the liquid state and unite them in the solid state, and after substantially sealing the mold, applying pressure to both metals while plastic, causing greater pressure to be exerted upon the metal of lesser contractive property as soon as the metal of greater contraction shrinks more rapidly, thereby causing the shrinkage of the two metals to be equalized during the solidification of all obstructed portions of the casting and until the said pressure is released.

7. The method of making composite castings in which two metals are poured into a. rigid mold containing a separation plate, which consists in applying pressure during solidification on such areas as are necessary to prevent the formation of fissures, cracks or undue internal stress in either of the metals cast.

CERROL E. REINHARDT.

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