US3166808A

US3166808A - Core reinforcement means

Info

Publication number: US3166808A
Application number: US755700A
Authority: US
Inventors: Francis C Moore
Original assignee: Pittsburgh Plate Glass Co
Current assignee: PPG Industries Inc
Priority date: 1958-08-18
Filing date: 1958-08-18
Publication date: 1965-01-26
Anticipated expiration: 1982-01-26

Description

Jan. 26, 1965 F. c. MooRE CORE REINFORCEMENT MEANs Filed Aug. 18, 1958 cw f mm MM M w n ma m W N 1 m F United States Patent Ofifice 3,166,808 CORE REINFRCEMENT MEANS Francis C. Moore, Indianapolis, lud., assignor to Pittsburgh Plate Glass Company, a corporatiou of Pennsylvauia Filed Aug. 18, 1958, Ser. No. 755,799 2 Clams. (Cl. 22-.-200) This invention relates generally to foundry cores used for casting metals and more particularly, it relates to a foundry core having a reinforcement in the form of distributed `fibrous material.

In the manufacture of Various castings such, for example,v as automotive cylinder headsV or engine blocks, it is customary to' provide reinforcement structure within thecores used for forming chambers within the cylinder head or engine g block such, for example, as water jackets Conventional reinforcement structure comprises Wire disposled within the core in such a manner as to provide the) necessary reinforcement when the core is placed in the mold and during pouring of the casting and. cooling thereof.

' Automotive. engines have become more and more complex asl the designs have provided greater power. Consequently, removal of the cores from the casting has become more and more diflicult. It has been the practice in foundries to shake the castings, thereby to disintegrate the cores so that the core material may fall from the casting in relatively small pieces. However, such shaking does not providerernoval of theV Wire or rod reinforcement, and because o f Vthe complex structure of automotive cylinder heads andh engine blocks, removal of such rod orl Wire has V becomeincreasingly difficult. In fact, the rod orv wirefrequentlybecomes welded to the casting and its completeV removal is almost impossible.

Accordingly, theprincipal object of this inventon is to provide a reinforced core of such character that it will maintain itnform during formation of the core, placement of thecoreinthe mold, and during the casting process, said core alsqbeing of such character that it will fracture or otherwise become sufliciently deformed during the shaking process of core removal that it is readily removable by means of the shaking process.

Another object of this inventon is to provide a reinforced core structure which is substantially more economical 'than conventional reinforced cores.

Still another object of this inventon is to provide a reinforced core comprising conventional core compositions having distributed therein fibrous material of such character that it will provide sufficient resistance to shear and elongation forces to support the core material during placement of the core in the mold, pouring of a casting, and Cooling thereof.

A still further object of this inventon is to provide a fibrous reinforcing material for foundry cores of such Character that the core material will adhere to the fibrous material when the core is baked, that no excessive amount of gas will be given olf during the baking of the core or the pouring of the casting, and that baking and casting processes will have no material effect on structural strength of the fibrous material.

In accordance with this inventon there is provided a reinforced foundry core consisting of a composition of conventional core forming materials in combination with glass fibres distributed uniformly throughout the core composition.

Further in accordance with this inventon there is provided a reinforced foundry core comprising conventional core compositions in combination with glass fibres distributed uniformly throughout the core composition and having a coating of thermoplastic or thermosetting resinous material.

The full nature of the inventon will be understood from the accompauying drawings and the following de-V scription and claims:

PIG. l is a top plan view of a core structure incorporating this inventon.

FIG. 2 is a cross section taken on line 2-2 of FIG. l.

Referring to the drawings, this inventon comprises a core structure for the casting of metals, said core structure consisting of a conventional composition of core Sand, oil and binders. This material is indicated generally at 13 in the drawings. A typical conventional core composition may consist of these materials mixed as indicated below in terms of parts by weight.

Parts Sand 65 Linseed oil 1 Starch 1 In accordance with this inventon strands of 'fibres of glass measuring froml 1A inch to 5 inches in length may' be mixed 'uniformlyzwith the above described core material or any other conventional core composition. The glass strands or fibres are'indicated at 11 in the drawings. Preferably, the glass fibersvor strands should be' mixed with the core material in a proportion of 1/50 of one percentlto 3 percent by Weight of the core composition.

The fibres 11 preferably should measure from approximately 1A inch to approximately 5 inches in length and may be coated with suitable thermoplastic or thermosetting resins. These coated fibres can be mixed with the core sand at the same time that the oil and bindersare mixed therewith, and the mixture may be placed in'the core box in the conventional manner. This forms a core Vhaving' reinforcing 'fibres distributed uniformly therein and extending in all'direotions through the core structure.

It is also within' the conceptv of this inventon to use strandsor fibres of glass cutto suitable length and treated with a cou'pling agent to adhere the glass strands or 'fibers to'thecore Sand-'Without the provision of 'the aforementioned thermoplastic or thermosetting resins coating on the strands or fibres. For example, the glass fibres or strands may be surface treated with .a coupling agent incorporated in a size which is applied to the fibres during their formation as disclosed in pages 305 and 306 of Modern Plastics Encyclopedia published September 1956 by Breshin Publications, Inc., of Bristol, Connecticut. Strands or fibres of glass treated as described in the aforementioned publication may be mixed with the core materials as described in connection with coated strands or fibres of glass. For coating the strands or fibres of glass it is possible to utilize plastic materials such as Vinyl polyrners and Vinyl chloride resins.

Where the fibers 11 are coated with thermoplastic or thermosetting resins, vinyl polymers can be used to coat p the glass fibres and when heated to 400 F. or higher,

the coating will carbonize and become very hard. As is well known, Vinyl chloride resins are produced in 4 general types, general purpose, paste resins, water dispersions and solution resins. Any of these types of Vinyl resins may be used to coat glass fibres for use in accordance with this inventon. i

Phenolic resins and polyester resins have also been found to be well adapted for coating glass fibres for use as reinforcement structure in accordance with this invention. For example, the glass fibres may be coated by dipping, spraying or other well known methods using phenolic resins containing hexamethylenetetramine as 'a curing agent. The resin may be diluted in alcohol to a viscosity slightly heavier than that `of water, and the glass fibres may be dipped therein by means of conventional Patented Jan. 26, 1965 and well known 'apparatus The coated fibres may then be cured by a catalyst method or by subjecting them to heat of the proper degree and duration. It will be readly understood that this invention is not limited to the use of the specific plastic materials disclosed herein so long as the plastic coating has the ability to adhere to theV core composition When the core is being baked. The plastic material must Withstand core baking temperatures of 400 F. to 550 F. Any plastic material which carbonizes within the range of 500 F. to l500 F. during the casting process has been found to retain the necessary structural strength to maintain the necessary reinforcement of the core. The carbon has been found to adhere to the core sand and the glass fibres to a degree suflicient to provide the desired reinforcement.

It is also within the concept of this invention to form conventional shell molds or cores utilizing as reinforcement material fibres of glass measuring from 1A to approximately 5 in the mixture of sand and resins that make up the shell mold or core. As in the oase of other types of cores, the glass fibres in the shell mold or core will forma reinforcing structure which increases the strength thereof. The various types of resins used in conventional shell molding processes adhere very well to glass fibres. It may or may not be necessary to coat the strands or fibres of glass depending upon whether or not the glass fibres are treated at the glass manufacturing plant to adhere to the resins, such treatment having been referred to in Modern Plastics Encyclopedia, previously cited.

Foundry cores having the structure dsclosed herein may be removed from the casting by shaking in the eonventional manner. The reinforcing 'fibres rattle out of the enclosed areas Within the castings along with the remainder of the core composition, and there are no difficulties such as those occurring in connection with the use of Wire reinforcement structures. It Will be readly apparent that this invention provides a reinforced core which is substantially cheaper than the conventional type which incorporates metallic Wire. The invention also provides a reinforced core which maintains its original strength and shape duringrcore baking and which will carbonize when subjected to the heat of pouring a casting. The structural strength of the core is enhanced by the bond provided by the plastic material between the core sand and the glass fibres. The core is easily formed into various shapes and does not emit gases to such an extent that the core and mold might be deformed. A further advantage resides in the fact that cores incorporating this invention are much lighter in Weight than |those having metallic Wire reinforcement, thereby reducing shipping costs.

The invention claimed is:

1. In the method of casting metal comprising pouring molten metal into a mold and around a rigid sand core, Cooling the metal in the mold to form a casting having a hollow portion in its eorresponding to the shape of the sand core and shaking the casting to disintegrate the core and permit it to be readly removed from within the hollow portion of the casting, the improvement which comprises using a core having straight glass fibers distributed in it to reinforce it and maintain its shape during the casting, said glass fibers being capable of breaking up into small portions along with the core during the shaking step.

2. A method of casting metal comprising pouring molten metal into a mold and around a sand core, the sand core being reinforced by means of straight glass fibers, Cooling the metal in the mold to form a casting having a hollow portion in its corresponding to the shape of the Sand core and shaking the casting to disintegrate the core and permit it to be readly removed from within the hollow portion of the casting, the said glass fibers breaking up into small portions along with the core durin g the shaking step.

References Cited in the file of this patent UNITED STATES PATENTS 512,845 Smith Ian. 16, 1894 1,778,329 Mason Oct. 14, 1930 2,239,53O Langenohl et al Apr. 22, 1941 2,468,956 Burg May 3, 1949 2,664,406 Armstrong Dec. 29, 1953 2,681,863 Croce et al. .Tune 22, 1954 2,688,007 Steinman Aug. 31, 1954 2,813,035 Sauter et al Nov. 12, 1957 2900338 Postelnek Aug. 18, 1959 2,907,084 Wood Oct. 6, 1959 2,983,004 Spier et al May 9, 1961

Claims

1. IN THE METHOD OF CASTING METAL COMPRISING POURING MOLTEN METAL INTO A MOLD AND AROUND A RIGID SAND CORE, COOLING THE METAL IN THE MOLD TO FORM A CASTING HAVING A HOLLOW PORTION IN ITS CORRESPONDING TO THE SHAPE OF THE SAND CORE AND SHAKING THE CASTING TO DISINTEGRATE THE CORE AND PERMIT IT TO BE READILY REMOVED FROM WITHIN THE HOLLOW PORTION OF THE CASTING, THE IMPROVEMENT WHICH COMPRISES USING A CORE HAVING STRAIGHT GLASS FIBERS DISTRIBUTED IN IT TO REINFORCE IT AND MAINTAIN ITS SHAPE DURING THE CASING, SAID GLASS FIBERS BEING CAPABLE OF BREAKING UP INTO SMALL PORTIONS ALONG WITH THE CORE DURING THE SHAKING STEP.