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> Aug. 6, 1946. R. K. HOPKINS . 2,405,254 MOLD CORE Filed Marqh '2, 1943 13”? 12-06114“ _ " INVENTOR , ‘ . BY Wk. ' - ATTORNEY Patented Aug. 6, 1946’ 2,405,254 UNITED STATES PATENT OFFICE 2,405,254 MOLD CORE ’ Robert KHopkins, New York, N. Y., assignor to The M. W. Kellogg Company, New York, N. Y_., a corporation of Delaware 1 Application March 2, 1943, SerialyNo. 477,738 4 Claims. (01. 22_17c) The present invention relates to molds, and more particularly to cores for shaping the inte rior of hollow castings. In casting hollow objects the use of a metal core is often desirable, particularly because of its durability. However, shrinkage of the cast metal makes removal of the core diiiicult, and will usu ally produce su?icient strain in said core to per manently deform it and render it unserviceable for further use. ' ‘ 2 / . tively. The angle betwe n these inclined wedge surfaces l1 and the coe?cient of friction between the contacting surfaces of the wedges I2 and the segments H are such that upon application of radially inward pressure on the segments H re sulting from shrink pressure the wedges l2 slip radially inwardly along the inner surfaces [4 of said segments. This radially inward sliding of the wedges l2 causes collapsible approachment 10 of the segments H, and resultant reduction in the One object of the present invention is to pro vide a new and improved metal core which can diameter of the core I 0. - The core sections I I and I2 are normally main be easily removed from a casting, and which will tained in expanded position shown in Fig. 2 by, not be permanently upset or deformed by the resilient means comprising radially extending coil shrinkage pressure of the casting thereon. 15 springs 29, retained at their inner ends in respec As a feature of the present invention, the core tive recesses 2| of a block 22 which is set in the is of sectional construction and is collapsible into interior of the core l0, and which may be of metal a smaller cross-section upon application of as shown or of suitable refractory material. The shrinkage pressure thereon. outer ends of these coil springs 20 bear against As a further feature, the sections of the core 20 the bases it of the wedges [2 to urge these wedges are automatically restored to expanded condition radially outwardly. Three of these springs 28 when the shrinkage pressure is removed. are arranged in the upper part of the core Hi and As another feature, the different sections of the three in the lower part. core are hollowed to permit circulation of a cool The internal hollow defined conjointly by the ing liquid therethrough. Various other objects, features and advantages of the invention will be apparent from the fol lowing particular description, and from an in spection of the accompanying drawing, in which core sections H and I2, has an equilateral hex agonal cross-section, and the block 22 has a smaller equilateral hexagonal cross-section sepa rated from the walls of said hollow by an inter Fig. 1 is a vertical section, somewhat diagram 30 vening border gap 23 affording the necessary space for the collapse or contraction of the matic, through a casting apparatus containing a core It. core which embodies one form of the present in venticn; To hold the core sections H and 12 in assem bled position shown in Fig. 2, there is provided Fig. 2 is a transverse section of the core taken at one end of the core li! a core retaining head on line 2—-2 of Fig. 1; and Fig. 3 is a transverse section of another form 35 plate 25 shown in Fig. 1 having a circular or hexagonal face groove 26. The upper ends of ~ of core embodying the present invention. the core sections l l and I2 have ?anges 21 ex Referring to Figs. 1 and 2 of the drawing, the tending in the plate groove 26 and abutting the core Iii comprises a series of similar segments H, outer peripheral wall of said groove in limiting three being shown, separated by wedges 12. These core sections I l and 42 are desirably made 40 expanded position of these core sections. The of metal having high heat conductivity such as groove 26 is wide enough to permit radially in copper. Each of the core segments H has an ward collapse of the core Ill. outer circular conformation i3 and an inner At its lower end, the core It seats on a retain chordal surface it intersecting said circular con 45 ing base member 28 shown in the form of a mold formation and slidably seating the wedges l2. stool having a circular recess 30 for receiving the The wedges [2 are approximately trapezoidal in lower end of saidcore. The outer peripheral cross-sectional outline with respective outer cir_ wall of the recess 39 by its engagement with the cular conformation l5 forming continuations of outer peripheries of the core sections II and I2, the segment conformations l3 in expanded con dition of the core shown in Fig. 2. Each wedge 50 limits radially outward movement of these sec: tions to the position shown in Fig. 2, while per l2 has a base it extending between the two chordal surfaces M of respective ?anking seg ments l l, and opposed inclined plane surfaces l7 slidably engaging said chordal surfaces respec mitting limited radially inward collapsing move ment of said sections under shrink pressure. The metal core sections ill and l I are respece 55 tively'hollowed and provided with .end walls to 2,405,254 3 permit circulation of cooling liquid, such as water, therethrough. In Fig. 1 is shown the application of the core ll! of Fig. 2 to a molding apparatus for produc ing and shaping hollow ingots. This apparatus comprises an outer tubular mold 35 desirably of 4 in the distributing head 61, and extends out wardly through the base 56. The shaft 51 has a central inlet duct 12 offset at its lower end for communication with the recess 66 and an outlet duct 13 offset at its lower end for communication with the recess '18. At its upper end, the inlet metal such as copper, and desirably provided with duct 12 extends through the turntable 58 and connects to the lower end of a pipe 15 passing a jacket 36 to permit circulation of a cooling me through the core block 22 and the upper core dium such’as water through the hollow mold retaining head plate 25. The upper end of this 10 walls. This tubular mold 35 is seated on the pipe 15 is connected to a header 16 above the stool 28 which also serves to seat the sectional * core [0. The cooling liquid is distributed from core 18 centrally in the interior of the mold. The a this header ‘I6 to the core sections H and I2 by core l0 de?nes with the outer mold 35 an annu respective pipes 11. Since the core sections H lar mold chamber 38 of circular or any desired and I2 are moved radially inwardly by the shrink 15 . cross-sectional con?guration. e ' pressure of the cooling cast metal in the mold The deposition of molten metal in the mold chamber 38 may be effected by any suitable man ner, thus molten metal may be poured in the chamber 38, the pipes 11 and 18 are desirably made of suitable yieldable material to permit this collapsing movement of the core sections. conventional way from a ladle or other molten The turntable 56 has an annular chamber 82 20 metal source or the metal may be produced di ‘communicating by ducts with the pipes 18 and rectly in mold chamber 38. For instance, a series also with theupper end of the outlet shaft duct of circumferentially spaced consumable electrodes 13. 45 may extend into the mold chamber 38 and be The distributing system described can also be submerged in a blanket of ?oating flux 48 with employed to circulate cooling liquid through the the lower ends of said electrodes spaced from the 25 stool 28 and the. outer mold 35. For that pur deposited molten metal 4'1 by a gap. Current is pose, the turntable 58 has a radial duct 85 con discharged through the electrodes 45 and the nected at its inner end to the turntable duct 12 metal 41 and across the intervening gap to pro and at its outer end to one end of a pipe 86. The gressively fuse the lower ends of said electrodes other end of this pipe 86 leads into the upper 30 and produce the metal 41. Other ingredients to inlet end of the mold 35. The lower discharge impart to the metal 41 the desiredanalysis may end of the mold 35 is connected to one end of be delivered to the fusing zone of the mold cham a pipe 81, the other end of which joins into the ber 38. The electrodes 45 are fed and the current outer end of a radial duct 88 in the turntable 50. supply adjusted so as to maintain a current dis The inner end of this radial duct 88 connects charge across the gap of substantially constant - with the annular chamber 82 in the turntable 56. characteristics. Although one inlet pipe 86 and one discharge ,During the fusing operations described, the pipe 81. are shown for the mold 35, it must be mold is rotated slowly to distribute evenly the understood that any number of these pipes may metal 41 deposited in the mold chamber 38 and be employed suitably distributed and arranged to assure that the whole surface of the deposited 40 to obtain the most effective cooling of said mold. metal is kept molten. This rotation of the mold To circulate cooling liquid through the turn may be effected in any suitable manner. For example, in the speci?c form shown, there is provided a turntable 58 seating the mold stool 28 and carrying on its lower face a crown gear 5!. Meshing with this crown gear 5! is a bevel gear 52 driven from any suitable source of power. This turntable 50 is supported by means of thrust bearings 53 on a bearing post 55 extending up w wardly from a ?xed base 56. A shaft 51 depend- . ing from and rigid with the turntable 59 is jour nalled in the post 55. The core block 22 may extend downwardly through an opening in the mold stool 28 and seat on the turntable 58 for rotation therewith. The body of metal 41 is grounded or otherwise connected to the current discharge circuit of the electrodes 45. This electrical connection may be effected, for example, by means of a conductor ring or ?ange 68 rigid with and depending from the turntable 50 and partially submerged in an annular mercury well 6|. This mercury well 61 is ?xed to the post 55 and connected to a lead 62 in the circuit of the electrodes 45. The stool 28 and turntable 50 being of metal or other suit 65 able electrical conductive material, the body of molten metal 41 will be connected to the current discharge circuit of the electrodes 45. The means for circulating a suitable cooling medium, as for example water, through various parts of the mold apparatus including the mold core ID, desirably comprises an inlet pipe 65 lead ing into the base 56 and connected to 'an ‘annular table 58, said turntable has a hollow 90 with one or more inlet connections 9i leading from the duct 85, and one or more outlet connections 92 joined to pipe or pipes 81. In the operation of‘the mold apparatus de scribed, as the deposited metal 4'! solidi?es and cools, the resultant shrinkage of said metal causes compression of the core segments I l in a radially inward direction. This shrinkage pressure causes the’ core wedges 12 to slide radially inwardly against the resisting action of the springs 28, so that the core segments H are moved radially inwardly and closer together. This collapse of the core In permits it to be easily removed from the cooled cast metal and to be reused for sub sequent casting operations. When the core i8 is removed from the casting, the various sections thereof will be restored to expanded condition under the biasing action of the springs 28. Although the core 10 of Fig. 2 has been shown in Fig. 1 as applied to a speci?c mold apparatus, it must be understood that as far as certain as pects of the invention are concerned, this core l8 maybe employed in connection with any other suitable mold apparatus. In Fig. 3 is shown another form of collapsible mold core embodying the present invention. In this form, four main core sections Ha are quad rantly arranged and separated by wedge sections 12a. Each of these main core sections Ha has an outer circular conformation 13a and a pair of inner converging plane surfaces Ma On which slide the wedges l2a. The core sections Ha and 75 let pipe 68 is connected to an annular recess ‘I8 recess 66 in a ?xed distributing head 61. An out 2,405,254 5 6 I211 are hollowed to permit circulation of cooling liquid therethrough, and are shaped to conjoint ly de?ne a continuous outer cylindrical surface in expanded position of said sections shown in Fig. 3, and a central hollow of substantially square cross-section. Extending in this core hollow is a block 22a of substantially square cross-section smaller in size than said hollow to de?ne with arranged sections having outer circular surfaces and inner plane substantially chordal surfaces, and a wedge between each adjoining pair of seg mental sections having inclined plane surfaces seated on the inner chordal surfaces of said pair of adjoining segmental sections and slidable therealong to permit said sections to move radial ly, the inclination of said wedge surfaces being the inner walls of the core section a marginal gap 23a affording the necessary space for the 10 such as to allow said wedges and said sections to move radially inwardly out of molding position collapsing movement of the core sections I la and upon application of compressive pressure by I2a. ‘Springs 20a have one end retained in re shrinking cast metal on said circular surfaces, spective recesses 2| a of the core block 22a and and means for yieldably resisting radially inward the other end bearing against the bases of the movement of said wedges. wedges l2a to urge these wedges radially out wardly. These springs 20a are provided at the upper and lower sections of the core block 22a to afford the necessary equilibrium. The recesses Zla are desirably arranged with each pair of op posed recesses in a different plane from the other adjacent pair of opposed recesses, so that the corners of the block 22a where these recesses are disposed are not unduly weakened. 3. A collapsible mold core comprising three similar substantially segmental circumferentially arranged metal sections hollowed to permit cir culation of a cooling medium therethrough, and having outer circular surfaces and inner plane substantially chordal surfaces, a metal wedge be tween each adjoining pair of segmental sections hollowed to permit circulation of a cooling me dium therethrough, said wedge having inclined The core of Fig. 3 can be arranged in a mold as indicated in connection with the core [0 of Fig. 1 to shape the hollow of a casting. As the plane surfaces seated on the inner chordal sur faces of said pair of adjoining segmental sections and slidable therealong to permit said sections core sections Ila are pressed radially inwardly by the shrink pressure of the cooling casting, the wedges l2a are forced radially inwardly to cause to move radially, the inclination of said Wedge surfaces being such as to cause said wedges to move radially inwardly upon application of com approachment of the main core sections lZa and collapse of the core against the resisting action 30 pressive pressure on said circular surfaces, a block in the interior space conjointly de?ned by said of the springs 20a. sections and said wedges, and springs between As many changes can be made in the above said block and said wedges urging said wedges ra apparatus, and many apparently widely di?erent embodiments of this invention can be made with out departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying draw ing shall be interpreted as illustrative and not in a limiting sense. What is claimed is: . l. A mold core comprising a plurality of sec tions having outer circular surfaces of the same radius, wedges spacing said sections and automat ically slidable radially inwardly upon the applica tion of shrinkage pressure of the cast material on the outer surfaces of said sections, a blockv in the interior of said core, and spring means bearing on said block and urging said wedges radially outwardly. 2. A collapsible mold core comprising three similar substantially segmental circumferentially dially outwardly. 35 4. A collapsible mold core comprising four sim ilar quadrantly arranged sections having outer circular surfaces respectively, and each having a pair of converging inner plane surfaces extend ing away from its corresponding curved surface, a wedge between each adjoining pair of sections having inclined plane surfaces seated on the in ner plane surfaces of said adjoining sections and slidable therealong to permit said sections to move radially, the inclination of said wedge sur faces being such as to allow said wedges and said sections to move radially inwardly out of molding position upon application of compressive pressure on said curved surfaces by shrinking cast metal, and spring means urging said wedges radially out wardly. ROBERT K. HOPKINS.