US2500494A - Casting method - Google Patents

Description

March 14, 1950 Filed May 17, 1946 D. M. JEFFERS 2,500,494

CASTING METHOD 2 Sheets-Sheet 1 INVENTOR. DOEYOTH) M; JEFFE/QS ATTORNEYS.

March 14, 1950 M. JEFFERS 2,500,494

CASTING METHOD Filed May 17, 1946 2 Sheets-Sheet 2 INV EN TOR.

DOROTHY M JEFFEQS wwfw ATTORNEYS.

Patented Mar. 14, 1950 UNITED STATES PATENT OFFICE CASTIN METHO Dorothy M. :Ieii'ers, Fresno, Calif assignor to Jeffers Manufacturing Company, Fresno, Calif.

Application May 17, 19lfi,.S erial No.670,522

6 Claims.

This invention relates to casting methods, and

vmore particularly to a casting method for forming articles of intricate design. The term intricate design, as it used hereinafter, is intended to embrace forms of minute and exacting r "Sign are iormedandare,further aggravated when the material employed is suchas to be flexible when-the article is completed. Not only is the castingdiflicultbut thetrimming of such articles is troublesome, time consuming. and. at best, very .inaccuate. For example, in theformation of fish lures, it is=desirable to simulateaccurately all oi the detailsof .the insect or other baitbeing embodiedin thelure. Further, the b odyand the extended portions of :the-lure should possess flex- .ibilityso ,as to havemotionimparted thereto by movement in the water. .Heretoiorethe iormationtof such'lures has been commercially impractical. Present .casting methods have not provided sufiicient accuracy. Theacutting of flexible material, suchas rubber, to. represent. minute horns, hairs,.feelers, legs and otherqdetails has not been possible because of the crawlingdof the material :as it is out.

Objects of the present invention, ,are therefore,- to :provide an, improved method or casting articlesoi' intricate design; to form such articles without trimming; to provide more intricate. details'in castings than has heretofore been possible; to expediteithe formation of-articles having forms of minute: and exact configuration; to provide-an economical method of formingarticles of intricate design; to reducerejections and waste incident to imperfection of *formation; and to provide a convenient method of forming buoyant, flexible; and durable fish luresaccurately simulating live bait.

Other objects of this "inventiomwill become apparents from the following description and appended cla ms.

iiln'lthe drawings:

Rig. 1 ls.aperspective:yiew. an open faee molding unitsuited..tottherraedce o th p es ireent invention having a substantially flat face surface.

Fig. 2 is ,a perspective view of an open face molding unit suited to the practice of the present invention having face surfaces disposed in. in tersecting planes and having a portion of said molding .iinit broken away to illustrate crosssectional configuration.

Fig. 3 illustrates the application of suitable moldingmaterial to the moulding unit of Fig. 2.

Fig. 4 demonstrates the employing of a tool in the filling of the molding unit.

Fig. 5 illustrates the use of the tool to remove all excess molding material from the molding r, unit.

.Fig. 6 is a section takenon line 6-6 oilifig. 5 demonstrating the mounting and securing of a fish hook in a fish lure being formed according to the method of the present invention.

Fig. 7 is illustrative of a step of the present invention in which the molding unit and molded articles are immersed for the removal .of said articles from the molding unit.

Fig. 8 is a perspective view of a fish lure pro- ,duced by the method of the present invention i1- ,liistrating the additionof intricate appendages thereto.

A mold is formed, as bydie casting, .oi stainless steel, plastic or other suitable material to provide all details desired in the finishedarticle. For fish luresthisnot only includesall the major elements of the lure but mayinclude in addition minute details, as for example, leg hair on simulated grasshoppers and antennas on simulated crickets.

The mold is preferably constructed to be. of open face type; that is onehaving its component partsexternallyaccessible. The face. of the mold thatis open is not necessarily limited to a single plane. It is frequently advantageous to form the-mold with a plurality of intersecting planes, providing access to various; portions of the mold, inorder to (cast component parts of the article being formed in proper angular relationship to ,each other. Further, the open faces or surfaces of access. need not. beplanes but are frequently of other predeterminedcontours selectedtoserve as a templet and assist in imparting .desired shapes; to exposed suriaces of articles being formed. ;It has been found desirableto provide a plurality of molds inia single. molding unit sofas to permit. PIQdUQiion of the articles. being. formed in multiples. :lreferablm,thev several. molds are relatively positioned in the molding unit to have their open faces in planes, or continuous surfaces, common to all molds. When this arrangement is possible the formation of the articles is greatly expedited.

In Fig. l a molding unit of the open face type is indicated generally at Ill having a substantially fiat face surface II in which a plurality of molds ii are formed incorporating all details desired in articles to be cast. As shown, the molds l2 are all open to the flat face surface l I which is a continuous surface common to all of the molds in the molding unit. The molds shown in Fig. 1 possess a form suitable as a fish lure and readily adapted to casting in a molding unit of the substantially fiat, open face type. Many fish lures simulating live bait are realistically flat on one side and minutely configured on the other. Such lures are conveniently formed in a molding unit of the type indicated to have their flattened surfaces in the plane of the flat face surface ll. Minute details of exacting and precise form, heretofore considered impossible to cast, are provided in the molds employed in the casting process of the present invention, as at It. The employment of such a fiat, open face mold in the methods of the present invention is made clearly apparent in connectionwith a further type of open face mold, presently 'more fully described. It will further become apparent that the flattened surface of articles cast in a molding unit of the type shown in Fig. 1 may be given a rounded or full effect by the addition of casting material thereto as by means of a syringe mechanism.

In Fig. 2 a molding unit 2i], also of the open face type, but in which the face is comprised of :z

a plurality of intersecting planes 2|, 22, and 23, respectively, is shown. A plurality of molds 24 are provided in the face for convenience in casting in multiples, as in the molding unit H]. The molds 24 are of a form suited to the production of simulated grasshoppers, a bait preferably produced in an open face mold in which said face is delineated by a plurality of intersecting planes. The major elements of a grasshopper lie in angular relation to each other, thus the molds are conveniently arranged in the molding unit to provide a body portion 25 and a head portion 26 in the plane 22. Front leg portions 2'! of the mold are conveniently formed in the plane surface 22 of the mold. Rear leg portions 28 of the mold are formed in the planes 2| and 23 in realistic relation to the head and body portions of said mold. Again, minute details of live bait to be simulated, heretofore considered impossible to cast from plastic or flexible material, are provided in the mold. Such details are characterized by leg hair portions of the mold as seen at 29. The breaking away of a portion of the mold 24, as in Fig. 2, clearly demonstrates the significance of employing an open face mold having its component parts externally accessible from a face thereof. It is to be clearly understood that the method of the present invention is not limited to the employment of the two types of open face molds shown but may utilize any other open face mold in which the face surface is of any continuous surface of suitable contour.

Many well known methods of forming the molds to produce exacting detail may be employed. The present invention is not limited to any particular method of mold formation, or type of mold other than it be of open face type.

Attention is also directed to spatulas or tools also shown in Figs. 1 and 2. A spatula 30 in Fig. 1, for use with the molding unit Ill having the flat face surface ll, provides a straight face engaging edge ;ll. A spatula 40 in Fig. 2 adapted for use with the molding unit 28 having the face comprised of intersecting planes 2!, 22 and 23 provides a face engaging edge 4| of complementary configuration are employed with molding units having open faces of other contour, the spatulas and the face contours of their respective molds preferably being of complementary configuration so that the spatulas may be drawn across the faces of their respective molding units while maintaining continuous, intimate contact therewith.

A plastic material, such as a mixture containing 60% to 85% solids of raw rubber and solvent, is prepared for the molds. It is clearly apparent that any suitable plastic materials may be employed. An example of a commercial form of raw rubber and solvent readily available is the molding compound 10099-A produced by American Anode, Inc., of 60 Cherry Street; Akron, Ohio. The material is colored as desired, as by adding water soluble pigment to the rubber solvent'mixture. When it is desired to impart buoyancy to the cast article, gas bubbles are stirred into the mixture as it is prepared. No invention is claimedin the plastic materials employed in the methods of the present invention. Many conventional forms are suited to the purpose.

An excess prepared plastic material, 43 as shown in Fig. 3, is placed in the mold 24 of the molding unit it and forced to conform to the configurations thereof. The mold, being of open face type, is well adapted to have the plastic material worked into its finest details.

The excess plastic material is then removed from the mold. When materials and a mold' of the character described are employed, even the most minute details of all the portions of said mold may be filled with a single stroke of a spatula or similar tool, as shown in Fig. 4. A return stroke, as demonstrated in Fig. 5, serves to remove all excess material. -Thus a filling stroke of the spatula and a return scraping stroke,

is sufficient to fill the molds in the molding units and remove excess material.

Prefabricated elements desired to be incorporated in the article being formed are arranged in the plastic material in the molds in predetermined position and bonded or'welded to the article being formed. In the formation of flexible rubber fish lures, for example; steel fish hooks 42 are so arranged, plastic rubber 43 dissolved in ammonia water and having water soluble pigment added to impart desired color is applied to the lure by means of a syringe mechanism. 44, of Fig. 6 in a position to bond the fish hooks intoplace. This same mixture is also employed, as desired, to add color, strength, and shape to other exposed surfaces of the lure. Thus, roundness or fullness can be imparted to fiat surfaces of cast articles when such isv desired.

The material is next hardened. The hardening may require cooling, drying, heating or chemical action depending upon the material employed. When the described material is. employed, the mold and its content are baked. When it is do;- sired to shrink the article being formed away from the mold, the baking is conducted at. low temperatures of approximately F. to F.

These temperatures are not to be considered 76 shrinkage'is desired; a higher temperature is employed, as forexample, of a magnitude of 200 F. to 220 F. These temperatures also are not to be'considered critical but merely relative indices of preferred temperatures. When buoyant lures are being formed and a rubber mixture having had gas bubbles mixed therein is employed, the baking temperature is first maintained in the higher of the given ranges to set the rubber and then reduced to the lower range to cure the sponge rubber interior.

, In the baking of the articles, it is important to consider the chemical characteristics of the plastic material. For example, where mixtures of rawrubber are employed it is highly desirable to avoid oxides of combustion and their harmful effects on the rubber by employing electric heating means to do the baking.

As demonstrated in Fig. '7, after the cast material has been hardened, the molding unit 20 and formed articles 45 are immersed in water to permit removal of the formed articles without the adhering to intricate portions 28 thereof to each other and to other such articles extracted from the molds. The immersing is conveniently accomplished in any suitable liquid as water 41 and the cast articles removed as indicated by the hand 48.

Intricate appendages of the formed article, such as feelers, horns, legs, and hairs of a fish lure, may be shaped by drawing fine threads 46 of the plastic material through small openings. Said appendages are secured in place by being inserted or abutted the cast lures 45 and Weldably secured by the addition of the diluted plastic material 63 as described in the bonding or Welding of the fish hook or other prefabricated elements into place.

Colored solutions of the original plastic material, solvent, and pigment are prepared as previously described and employed to trace details on the formed article for decorative and realistic purposes.

The completed articles are then dusted to prevent undesired adhesion of the articles to each other or of component parts, as is Well known in the production of rubber and plastic articles. Powdered tale is suitable for this purpose.

The method herein described is advantageously employed for the formation of fish lures, simulated fiowers, and other articles of intricate design. The said method permits the formation of such articles Without trimming; permits the simulation of more intricate details than heretofore possible; reduces Waste incident to imperfection of formation; and provides a convenient and economical method of forming buoyant, flexible and durable fish lures accurately simulating live fish bait.

The examples given herein above are intended to illustrate my invention and not to restrict it or the appended claims.

Having described my invention, What I claim as new and desire to secure by Letters Patent is:

1. In the art of casting rubber articles which comprises filling an open face mold with a flowable mixture comprising rubber and curing the same, the novel step which comprises applying water to the exposed surface of the molded and cured article and to the mold and while such Water is present, stripping said article from said mold.

2. In the art of producing cast articles of minute configuration which comprises filling an open face mold with a fiowable material having adhesive and elastic properties when cured and 6 curing the same, the novel step which comprises applying water to the exposed surface of the molded and cured article and to the mold and while such water is present, stripping said article from said mold.

3. In the art of forming rubber articles which includes filling an open face mold with plastic rubber and curing the same, the novel step comprising applying a film of Water to the face of the mold and to the exposed surface of the molded article and stripping said article from said mold while such film is present and overlays the molded and cured article and adjacent face of the mold.

4. A method of producing castings of minute and exacting configuration comprising dispersing a plastic mixture of rubber and solvent therefor over the face of an open face mold which face is defined by a plurality of intersecting angularly related planes and has cavities formed therein conforming to the detailed surface configurations of one side of the article to be cast, wiping excess plastic mixture from the face of the mold by a stroke in alignment with the intersections of the planes of the face with a tool having a shape complementary to the intersecting planes, curing the mixture in the mold, applying water to the mold and the molded and curedarticle, and stripping the molded article from the mold while such water is present.

5. In the art of molding articles of rubber such as fish lures having intricate and minute physical appendages, the steps comprising depositing by gravity, rubber in fiowable condition in a plurality of substantially aligned independent open faced cavities provided in a plane surfaced mold, and allowing more rubber than is necessary for filling the mold cavities to be deposited, wiping the rubber while it remains fiowable into all the interstices of the cavities by stroking a straight edged scraper across all the rubber deposits with at least one stroke in one direction while maintaining the scraper edge in contact with the plane surface of the mold, thus insuring a complete r filling of all but the first cavity in the series by carrying some rubber in advance of the scraper from one cavity to the next, pro-trimming the rubber in the molds so that no subsequent trimming is necessary and insuring a complete filling of the said first cavity in the series, by making at least one return stroke of the scraper over substantially the same path and distance as the initial stroke and with the scraper edge in contact with the plane surface of the mold, thus also removing excess rubber with none overflowing the mold cavities onto the plane surface of the mold, hardening the rubber in the cavities to a consistency of cured soft rubber, Wetting the surface of the hardened articles with water, and while the surface remains wet stripping the articles from the mold by force applied directly perpendicularly to the plane surface of the mold.

6. The herein described method of making a molded rubber article representing a living creature, by the use of a mold plate having a flat upper surface and provided in said surface with an open-top mold recess having portions corresponding to the body and other parts of the creature, which method consists of discharging directly into the body-forming portion of the :mold plate recess a quantity of fluent rubber material sufficient to fill the entire mold plate recess and to project above the upper surface of the :mold

plate, forcing the material into all portions of the mold plate recess and smoothing it off substantially flush with the upper surface of the mold j REFERENCES CITE]? plate, removing the surplus material from the H upper surface of the mold plate, dropping an f z i g gs fg are of record in the additional quantity of the material on the portion of the initial material which is within the 5 UNITED ES PATENTS body-forming portion of the mold plate recess to Number Name Da build up the body of the article above the upper 214 Ratingnier Sept surface. of the mold plate, and then subjecting 1 891088 Gammeter 1932 the material to vulcanizing heat While in the 2 24 9 Ross'et 1 July 1941 mold Plate recess 2272704 Harding Feb 101942 DOROTHY JEFFERS- 2,299,520 Yant Oct. 20, 1942. 2,330,330 Beal et a1 Sept. 28, 1943\ 2,341,999 Lennington Feb. 15, 1944 2,378,882 Habib et a1. June 19, 1945 15 2,400,482 Brannon May 21, 1946

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