US3220071A - Combination ingot molds and cores and methods of making ingot molds and cores - Google Patents

Description

NOV 30, 1965 F. DETTORE COMBINATION INGOT MOLDS AND CORES AND METHODS OF MAKING INGOT MOLDS AND CORES Filed Jan. '7, 1965 lNvENToR Frank Detore Page.

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United States Patent 3,220,071 COMBINATION INGOT MOLDS AND CORES AND METHODS F MAKING INGOT MLDS AND CORES Frank Dettore, McDonald, Pa., assigner to G. E. Smith, Inc., a corporation of Pennsylvania Filed Jan. 7, 1963, Ser. No. 249,829 Claims. (Cl. 22-198) This invention relates to molds and cores for making ingot mol-ds and to methods of making ingot molds and particularly to a single stage method of making ingot molds using a one-piece pattern.

In the manufacturing of ingot molds it has long been the practice to use multiple piece patterns or multiple patterns .and a multiple step method of making the mold and core for the final production of ingot molds. This requires a large expenditure of money for patterns and for pattern storage as well as considerable expenditures in handling and labor made necessary `by the separate forming of the cores and molds. In addition, the problem of insuring a uniform thickness of the walls of the final cast ingot mold has plagued this particular segment of the casting industry. The making of a core and a mold together with a separate stool raises problems of fin-al assembly which are time consuming and costly. The sand and binder mixture used in the past has required a basic green strength at the time of ramming of at least 3 lbs. and usually in the area of 6 to 8 lbs. Anything less than this would not produce -a satisfactory mold and/ or core, moreover the mold and core have been washed with a wash made up of non-refractory highly volatile solids to form a gas shield in the mold. I have discovered a mold and core assembly and a method of forming molds and cores for the casting of ingot molds which makes possible great savings in labor as well as insuring uniform quality in the ultimate ingot -mol-d as exemplified by uniform wall thickness in the final mold.

I preferably provide a mold and core assembly which are formed in one ramming operation so that both the mold and the core are formed simultaneously about a single pattern. In the practice of my invention I place a hollow perforate metal arbor centrally of a drag mold. A mixture of sand and binding agent having a green strength less than 3 lbs. and preferably zero green strength is rammed into the drag flush with the top of the drag mold. A one-piece pattern having the contour of the ultimately desired ingot mold is centered over the arbor on the rammed sand in the drag. A stripping plate is placed on the sand spaced from the outer periphery of the pattern and extending to the edge of the drag mold. An outer flask is placed around the pattern on the stripping plate and attache-d thereto. Sand and binder having a green strength less than 3 lbs. and preferably Zero green strength is then rammed about the pattern of the arbor to the level of the inlet gate. This low green strength is essential to obtain sand and binder flowability. A tile gate is assembled while the ramming continues until the top of the flask is reached so that the core and mold are simultaneously formed and rammed. The ramming is preferably carried out while imparting shock to the flask either by vibration or jolting. The sand is allowed to set up approximately to 45 minutes. The flask and sand are then removed from around the pattern. The pattern is drawn from around the core. The mold and core are then washed with a refractory wash which may be Zircon, silica or carbon or any combination thereof suspended in either Water or alcohol and dried. The mold is returned to its position on the drag flask and is then ready for use.

In the foregoing general description I have set out a general description of the practice of my invention. This invention will be better understood by referring to the drawings in which:

FIGURE 1 is a section through a mold flask assembly with a pattern in place according to my invention;

FIGURE 2 is an isometric View of a one-piece pattern as used in my invention;

FIGURE 3 is an isometric view of a drag and arbor according to FIGURE 1; and

AFIGURE 4 is a section through a mold flask assembly for a second embodiment of my invention.

Referring to the drawings, I have illustrated a base plate 10 having an open center vent 11. A perforated metal .arbor 12 is attached to the base plate 10 by bolts 13. A drag flask 14 is placed on the base plate 10 by conventional rotating pins and clips 15. Cheek flasks carrying a strip plate 17 attached to the bottom thereof are placed on the drag flask containing rammed sand 18. The cheek flasks may be provided with chucks 19 to firmly bond the sand in the cheek flask. A pattern 20 is centered around the arbor 12. The sand and binder 21 are simultaneously rammed into the cheek flask and inside the pattern 20 to form the core .and mold about the pattern 20. The sand-binder mix must be one which Ihas a green strength less than about 3 lbs. and preferably zero or less than 1 lb. green strength at the time of ramming and capable of setting up free of deformation without heat. Gate tiles 22 are inserted as the sand ramming continues until the top of the cheek flask is reached. -During the ramming operation the flask assembly is vibrated. A tie -bar 23 is attached to the top of the arbor 12 to hold the pattern 2li in place. As soon as the sand 21 has set, the cheek flask and attached sand 21 are pulled away from the pattern 20. The tie bar 23 is removed and the pattern 20 is pulled from around the arbor and core sand 21. The mold and core are coated with a refractory wash of silica, Zircon or carbon in water or alcohol. The cheek flask and mold sand 21 are returned to their original position and the assembly is ready for the pouring of an ingot mold. This practice eliminates the need for separate core and mold patterns. It eliminates the need for multiple piece patterns. It makes possible the molding of the core and mold for ingot mold casting in a single ramming operation.

Preferably the sand used to form the core and mold is bonded with a binder requiring no heating such as a cement-dextrose binder or a furan resin binder, thus eliminating the need for placing the mold and core in a furnace to set the same.

In the alternative embodiment shown in FIGURE 4, I provide a base plate and arbor structure identical with that of FIGURE 1. An intermediate flask 40 is placed about the pattern 20a and the core and mold portion adjacent the pattern are rammed with a sand containing a binder capable of setting without the addition of heat at a green strength less than 3 lbs. and preferably less than 1 lb. The intermediate flask 40 is then removed and the area between the cheek flask and the sand surrounding the pattern is rammed with sand containing a conventional heat curing binder at a green strength of about 6 lbs.

By this practice I am able to eliminate a large proportion of expensive binders which set without the use of external heat and achieve essentially the same result as in the case where all of the sand is bonded by a non-heat requiring binder, the outer layer of sand Ibeing supported by the intermediate sand layer and the base plate. This practice naturally reduces the expense of binders used and adds an additional factor of savings to the practice of this invention.

While I have illustrated a present practice and embodiment of this invention it will be understood that this invention may be otherwise embodied within the scope of the following claims.

I claim: l

1. The method of forming a mold and core for casting ingot molds comprising the steps of forming a base of sand and binder in a drag mold around a central hollow perforate arbor, placing a one-piece pattern equidistant around the arbor, placing a iiask assembly around the pattern on the drag mold, simultaneously ramming a sand and binder mixture having a green strength of less than about 3 lbs. about the inside and the outside of the pattern, setting the sand and binder mixture, stripping the outer flask and sand from the pattern while holding the pattern in position about the arbor, stripping the pattern from around the sand and arbor within the pattern and returning the flask and sand 4binder to its original position on the drag flask.

2. The method of forming a mold and core for casting ingot molds comprising the steps of forming a base of sand and binder in a drag mold around a central hollow perforate arbor, placing a one-piece pattern equidistant around the arbor, placing a flask assembly around the pattern on the drag mold, inserting an intermediate flask between the ilask and pattern, simultaneously ramming a sand and binder mixture having a green strength of less than about 3 lbs. about the inside and the outside of the pattern Within the intermediate Iask, setting the sand and binder mixture, stripping the intermediate ilask, ramming a standard sand and binder mixture within the remaining area of the outer tiask, stripping the outer ilask and sand from the pattern while hol-ding the pattern in position about the arbor, stripping the pattern from around the sand and arbor within the pattern and returning the ilask and sand and binder to its original position on the drag ilask.

3. The method of forming a mold and core for Casting ingot molds comprising the steps of forming a base of sand and binder in a drag mold around a central hollow perforate arbor, placing a one-piece pattern equidistant around the arbor, placing a flask assembly around the pattern on the drag mold, simultaneously ramming a sand and furan resin binder mixture having a green strength of less than flask and sand from the pattern while holding the pattern setting the sand and binder mixture, stripping the outer ask and stand from the pattern while holding the pattern in position about the arbor, stripping the pattern from around the sand and arbor within the pattern and returning the flask and sand and binder to its original position on the drag flask.

4. The method of forming a mold and core for casting :ingot molds comprising the steps of forming a base of .sand and binder in a drag mold around a central hollow jperforate arbor, placing a one-piece pattern equidistant .around the arbor, placing a ilask assembly around the patv'tern on the drag mold, simultaneously ramming a stand `:sand and binder in a -drag mold around a central hollow perforate arbor, placing a one-piece pattern equidistant .around the arbor, placing a ask assembly around the pattern on the drag mold, gating the mold to enter tangentially of the mold cavity whereby erosion of the core is avoided, simultaneously ramming a sand and binder mixture having a green strength of less than about 3 lbs. about .the inside and the outside of the pattern, setting the sand tand binder mixture, stripping the outer -ask and sand from the pattern while holding the pattern in position about V the arbor, stripping the pattern from around the san-d and arbor `within the pattern and returning the ilask and sand and binder to its original position on the drag flask.

References Cited by the Examiner UNITED STATES PATENTS 16,688 2/1857 Leonard 22-198 971,045 9/1910 Kerr et al 22-172 1,262,719 4/1918 Walker 22-198 1,862,975 6/ 1932 Meloche 22-172 2,770,855 lll/1956 Phillips 22-136 I2,860,392 l1/l958 McCracken 22-134 3,008,205 11/1961 Blaies 22193 OTHER REFERENCES Dietert: Modern Core Practices and Theories, page 417, copyright 1942.

MARCUS U. LYONS, Primary Examiner.

MICHAEL V. BRINDISI, Examiner.

Claims (1)

1. THE METHOD OF FORMING A MOLD AND CORE FOR CASTING INGOT MOLDS COMPRISING THE STEPS OF FORMING A BASE OF SAND AND BINDER IN A DRAG MOLD AROUND A CENTRAL HOLLOW PERFORATE ARBOR, PLACING A ONE-PIECE PATTERN EQUIDISTANT AROUND THE ARBOR, PLACING A FLASH ASSEMBLY AROUND THE PATTERN ON THE DRAG MOLD, SIMULTANEOUSLY RAMMING A SAND AND BINDER MIXTURE HAVING A GREEN STRENGTH OF LESS THAN ABOUT 3 LBS. ABOUT THE INSIDE AND THE OUTSIDE OF THE PATTERN, SETTING THE SAND AND BINDER MIXTURE, STRIPPING THE OUTER FLASK AND SAND FROM THE PATTERN WHILE HOLDING THE PATTERN IN POSITION ABOUT THE ARBOR, STRIPPING THE PATTERN FROM AROUND THE SAND AND ARBOR WITHIN THE PATTERN AND RETURNING THE FLASH AND SAND BINDER TO ITS ORIGINAL POSITION ON THE DRAG FLASK.

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