US3295175A

US3295175A - Gasifiable feeder pattern with recess to compensate for compressive force of form material

Info

Publication number: US3295175A
Application number: US398472A
Authority: US
Inventors: Erich M Krzyzanowski
Original assignee: Full Mold Process Inc
Current assignee: Full Mold Process Inc
Priority date: 1962-09-21
Filing date: 1964-09-14
Publication date: 1967-01-03
Anticipated expiration: 1984-01-03

Description

1967 E. M. KRZYZANOWSKI GASIFIABLE FEEDER PATTERN WITH RECESS TO C ENSATE FOR COMPRESSIVE FORCE 0F F M MATER Filed Sept. 14, l

ill/l INVENTOR.

MARIA KRZYZANOWSKI ERIGH BY RONALD E. BARRY United States Patent M Wis., a corporation of Delaware Filed Sept. 14, 1964, Ser. No. 398,472 9 Claims. (Cl. 22-158) This invention relates to a casting arrangement and method; and, more particularly, it is concerned with improvements relating to spherical type feeder head patterns.

This application constitutes an improvement over the spherical type feeder head, as shown and described in United States patent application 298,676, filed July 30, 1963, and assigned to the same assignee. As described in said application, feeder heads are used to provide a reservoir or storage space for the casting charge at points remote from the inlet to compensate for shrinkage in the casting. This type feeder head has been found to be easier to use than the installation of heating means, such as thermit mixtures, which are used to reduce the cooling rate at points where shrinkage normally occurs. A spherical feeder head can be placed on or secured to any point of the pattern, depending on whether it is a removable type pattern; i.e., wood, or a gasifiable pattern. If the former type of pattern is used, the feeder head will be left embedded in the forming material when the pattern is removed. The advantages of this should be apparent since no further operations have to be performed on the mold after the pattern has been removed.

It has been found that in using a spherical feeder head in a casting method, where the form material is placed under high compressive forces, such as the use of replaceable-type patterns, some difficulties have been encountered. These difficulties are caused by the resiliency of the gasifiable material used for making the feeder head pattern. When under compression, the height of the feeder head is reduced; and when the compressive force is released, the feeder head will expand, often cracking the form material. The principal object of the invention is, therefore, to provide an improved spherical feeder head which overcomes the above difliculties.

Another object of the present invention is to provide an improved spherical feeder head in which a greater proportion of the stored or reserve casting material is available to compensate for shrinkage cavities.

Still another object of the present invention is to provide an improved method of locating and securing a spherical feeder head pattern to a casting pattern.

These objects are accomplished by providing a cylindrical or conical locating peg on the surface of the casting pattern at the point where shrinkage cavity is most likely to occur. The feeder head pattern is provided With a corresponding recess in the lower end of the pattern which has a height slightly greater than the height of the peg. The feeder head pattern is then placed on the casting pattern on the locating peg which provides the dual function of locating and holding the feeder head pattern in position. Since the spherical feeder head has a frustum type connection, there is a circular contact area on the pattern. By providing a recess in the end of the frusturn connection the circular contact area is reduced to a ring contact area which will be the area subjected to the compressive force. The height of the recess is made greater than the height of the peg so that the initial compressive force will be taken by the contact ring. The compressive force will cause a permanent deformation of the pattern material at the ring area so that there will be no expan- 3,295,175 Patented Jan. 3, 1967 sion of the ring after the compressive force is releasedto crack the form material.

Other objects and advantages will become more readily apparent when the following detailed description is read in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of a typical casting pattern with a locating peg on its upper surface at the point of anticipated shrinkage.

FIG. 2 is a side view of the spherical feeder head above the peg on the casting pattern.

FIG. 3 is an enlarged side elevation view in a section showing the spherical feeder head positioned on a frustoconical peg.

FIG. 4 is an enlarged side elevation view in section of a spherical feeder head mounted on a cylindrical peg.

Referring to the drawing, a casting pattern 10 is shown which includes an outer circular surface 12 and a central hub 14. The casting pattern can be made of any of the commonly used pattern materials such as wood, metal, wax or expanded plastic material. The latter is commonly referred to as a gasifiable pattern of the nonremoving type. A peg 16 is provided in the center of the hub to locate and support a spherical feeder head 18. As seen in FIG. 2, a spherical feeder head is located in the center of the casting where the shrinkage cavity is most likely to occur. With this type of casting the inlet and outlet risers are connected to the outer rim of the pattern.

Referring to FIG. 3, an enlarged cross section is shown of a spherical feeder head 24, having a frusto-conical recess 25, with a fiat inner surface 27, mounted on a frusto-conical peg 26, which has been cut off at the top 28. The recess is made slightly larger than the outer dimensions of the peg, leaving a space 21 between the side walls of the peg and the recess, and a space 23 between the top of the peg and the upper surface of the recess. The lower connecting end of the spherical feeder head will now have a ring type contacting surface 30 which Will engage the top surface of the casting pattern around the peg. When compressive force is applied to the spherical feeder head pattern, the entire force will be absorbed by the ring contact area. The space between the top of the peg and the inner surface of the recess, and between the side walls of the peg and recess, will allow for a limited amount of motion of the feeder head which will be completely absorbed by the ring portion of the pattern. Since the ring area is of small cross sectional area, the crushing action will produce a permanent deformation of the lower end of the feeder head pattern so that there will be little or no rise in the feeder head after the compressive force is released.

A conical dimple 32 may be cut in the top of the feeder head to increase the amount of casting material available for shrinkage. If the dimple is omitted, it has been found that casting material will adhere to the top of the feeder head cavity. With a conical dimple the inner dome shape is broken, with only a point 34 on the end of the cone resisting the free flow of the molten casting charge from the cavity.

In FIG. 4, a modified type of spherical feeder head is shown having a cylindrical recess 40 with a fiat inner surface 42. A cylindrical peg 44 having a flat upper surface 45 is provided on the casting pattern of substantially the same outer diameter as the inner diameter of the recess. The height of the recess is made slightly larger than the height of the peg leaving a space 43 between the peg and inner surface of the recess. With this arrangement a tight fit will be provided between the feeder head and the peg which will hold the feeder head in position in the pattern. The recess will produce a small ring contact area 46 on the spherical feeder 3 head pattern which will engage the casting pattern surface and absorb the initial compressive force.

When the feeder head pattern is used with a casting pattern of the same material, expanded plastic material, or in a casting operation where little or no compressive force is applied to the form material, the recess in the pattern need not be of any greater dimensions than the peg. That is, the peg can be used as a locating and holding surface for the feeder head with the recess of the same dimensions to provide a tight fit. It should also be noted that spherica as used herein refers to a casting pattern which has either partially or wholly arcuate outer surface sections and is not necessarily a completely round or spherical body. Elliptical, cylindrical, pear shaped and spheres all are considered within the term spherical. The important consideration is the connection of the feeder head to the casting pattern by an undercut design to aid in removing the riser from the casting.

It should also be noted that the same result can be accomplished without the use of a peg on the casting pattern surface. A feeder head having a central recess in its lower end can be set on top of a casting pattern at any point and embedded in the mold material as is presently done. The peg provides a better locating and holding surface on the casting pattern as well as a permanent locating point on the casting pattern for production line operations.

Although only a few embodiment-s of the present invention have been shown and described, it should be obvious that various changes and modifications can be made without departing from the scope of the appended claims.

What is claimed is:

1. In a casting arrangement, in combination, a pattern having substantially the configuration of an article to be cast, said pattern having at least one protruding member of the same material as the pattern, and having a predetermined outer configuration, a feeder head pattern of substantially spherical configuration and consisting of a cellular material which is compressible and is gasifiable at the temperature of the molten casting charge, and

said feeder head pattern being formed with a recess of substantially the same configuration as the protruding member but of slightly greater dimensions, with the outer edge of said recess defining a thin wall ring-type contacting surface for engagement with said pattern, whereby on subjecting said feeder head and pattern to compressive forces the material forming the ring type contacting surface will be permanently deformed.

2. In a casting arrangement, according to claim 1, where said protruding member and said recess have a frusto-conical configuration.

3. In a casting arrangement, according to claim 1, wherein said protruding member and said recess have a cylindrical configuration.

4. A feeder head pattern, .said feeder head pattern consisting of a cellular plastic material which is gasifiable substantially without residue upon subjection to a molten casting charge, said pattern for a casting pattern, having a substantially spherical outer configuration, with a frustoconioal connecting section,

said section having a recess therein to define a thin ring-like mounting surface, whereby on subjecting said feeder head to a compressive force said cellular plastic material forming the ring-like mounting surface will be permanently deformed.

5. A feeder head, according to claim 4, wherein said recess is conical in configuration.

6. A feeder head, according to claim 4, wherein said recess is cylindrical in configuration.

7. The combination of a casting pattern having at least one protruding peg on its outer surface, at the point where shrinkage cavity is most likely to form, and a spherical feeder head pattern having a hollow tubular connecting section with a ring-type contacting surface at its lower end, said feeder head pattern being made of a material which will gasify at the temperature of the molten casting charge whereby, on placing said feeder head pattern on said peg, the material forming the ringlike contacting surface on the feeder head pattern will be deformed by any compressive force used in setting the form material, thereby preventing any cracking of the form material after the compressive force is released.

8. The combination, according to claim 7, wherein said peg and said tubular connection both have frustoconical shapes.

9. The combination, according to claim 8, wherein said peg and said tubular connection both have cylindrical shapes.

References Cited by the Examiner UNITED STATES PATENTS 825,090 7/l906 Turner 22-134 2,845,667 8/1958 Frischkenecht 22134 3,157,924 1 1/1964 Smith a 22-196 FOREIGN PATENTS 1,089,126 9/1960 Germ-any 595,795 12/1947 Great Britain OTHER REFERENCES Foundry Trade Journal, vol. No. 90, pages 357-360, Apr. 5, 1951.

J. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No n 3, 295, 175 January 3, 1967 Erich M. Krzyzanowski It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4 line 4 after attern first occurrence inser r for a casting pattern line 7, strike out "for a casting patternm (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents

Claims

1. IN A CASTING ARRANGEMENT, IN COMBINATION, A PATTERN HAVING SUBSTANTIALLY THE CONFIGURATION OF AN ARTICLE TO BE CAST, SAID PATTERN HAVING AT LEAST ONE PROTRUDING MEMBER OF THE SAME MATERIAL AS THE PATTERN, AND HAVING A PREDETERMINED OUTER CONFIGURATION, A FEEDER HEAD PATTERN OF SUBSTANTIALLY SPHERICAL CONFIGURATION AND CONSISTING OF A CELLULAR MATERIAL WHICH IS COMPRESSIBLE AND IS GASIFIABLE AT THE TEMPERATURE OF THE MOLTEN CASTING CHARGE, AND SAID FEEDER HEAD PATTERN BEING FORMED WITH A RECESS OF SUBSTANTIALLY THE SAME CONFIGURATION AS THE PROTRUDING MEMBER BUT OF SLIGHTLY GREATER DIMENSIONS WITH THE OUTER EDGE OF SAID RECESS DEFINING A THIN WALL RING-TYPE CONTACTING SURFACE FOR ENGAGEMENT WITH SAID PATTERN, WHEREBY ON SUBJECTING SAID FEEDER HEAD AND PATTERN TO COMPRESSIVE FORCES THE MATERIAL FORMING THE RING TYPE CONTACTING SURFACE WILL BE PERMANENTLY DEFORMED.