US2216098A - Arbor for and method of forming a cored mold - Google Patents

Description

Sept. 24, 1940. F. FQELLINGWOOD ET AL 2,216,093

ARBOR FOR AND METHOD OF FORMING A CORED MOLD FiledDec. 9, 195a f/en A Ma l I ATTORNEY Patented Sept. 24, 1940 UNITED STATES ARBOR FOR AND METHOD OF FORMING A comm MOLD Finley F. Ellingwood,.Plainfield, and Stephen A. 'Mraz, Perth Amboy, N. J., assignors, by mesne assignments, to Union Carbide and Carbon Corporation, New York, N. Y., a corporation of New Application December 9, 1938, Serial No. 244,726

4 Claims.

This invention relates to the molding of artiby dipping arbors into a con'gealable material,

preferably molten lead-,type metal,..and thelike.

The preparation of articles frorn castingresins and similar plastic materials requires-the iriaki'ng of molds by chilling [and hardening 'a'fl lowmelting point substance, such as-leadflor a similarly' congealable material around an arbor 'or die', re- I v moving the mold or'. shell so formed, pourlngj'a viscous resin into the'mold andhardening the.

cast resin by placing the moldfja'nd its contents into a temperature controlled oven, This procass is satisfactory for castingsolidforms as knife" handles, pipe stems, rods, and the like where a core is not required; but in attempting to obtain hollow cast resins in this manner by preparing slush-cast molds with integral cores it has been found that air is frequently entrapped in the bore of the arbor for forming the core and prevents the lead from rising to the same height each time a slush mold is made. In certain cast articles, however, it is desirable to have openings or bores extending a fixed and/or a predetermined length into the casting, as for example, in castings for knife handles, utensil handles, forks, pencil barrels, and the like.

It is the object of this invention to provide integrally cast cores forming openingsof definite and predeterminable length in resinous cast artitles and to produce hollow articles which re-:; quire no further machining after being removed from the .casting mold. Brieflyrtbepresentinserves to shear away the lead slugfrom'both the core and the mold wall. v The foregoing object, as well as drawing which illustrates an embodiment of the invention. 1

In the drawing:

Figure 1 is a lateral view of an arbor, showing vention provides an improved arbor having a bore extending in a longitudinal or axial direc; tion partially therethrough and connected by-ai' but the subseclucnt withdrawal-of the arbor other andad-f ditional objects, will bemore readily understood j by referring to the following description and'the a lead shell or casting mold deposited on the arbor, a portion of the lead shell being cut away to show the structure of v the arbor more clearly;

Figure 2 is a vertical sectional view of the arbor showing the inter'nal structure of the slush molded lead shell more clearly;

Figure 3 is a vertical section of the apparatus 'shownin Fig. l with the arbor almost withdrawn and the lead slug dropping out of the air vent; and

.Figure '4 is a perspective view of a finished hardened cast resin body removed from the lead casting shell and provided 'with an opening of definite predetermined length and shape.

Referring now in more detail to the drawing, an arbor Fig. 1 comprises a handle H, an insulating sheath l2 and a backing plate III which has mounted on its lower surface a molding member l3; screw bolts l9 secure the member to the plate. The section of the arbor in Fig. 2 shows the axially or longitudinally disposed bore l5 running to any predetermined depth into the molding member l3. At the end of the bore a vent I6 is provided in the side of the molding member I3 and is tapered to broaden outwardly. The vent as shown is laterally directed, i. e. ex-

tends in a radial direction through the member from the end of the bore IE to open at the outer longitudinal surface ofthe member and thereby forming cutting edges at the bore terminal and the exterior surface; the vent need only be large enough-to insure. escape of gas.

' When dipped into molten lead, a lead shell or casting form freezes and hardens conformably over the molding member l3 and the portion of the backing plate dippedtherein. The arbor is then withdrawn from the lead bath and the lead shell further cooled. When sufliciently hardened, the lead skinlayer or shell is jarred loose from the arbor; and; the arbor is then withdrawn, leaving a relatively clean and sharply formed Ieadc'asti'ngshell or mold. I

The lead shell [4 that is formed on the arbor has an'internally, disposed core 20 shown in section in FigsfZand 3) formed integrally therewith; :the core -10 is formed when the molten lead, or similar congealable material, runs up into the bore l5 of. the member l3 and displaces the entrapped which) escapes by being 'forced 'out'through the vent l6,.-' Upon further sub-*- I mer'siomof the .arbor a lead slug lt'l forms v in the vent li'and bridges across the core 20 and sis is determined by the position of the air vent l6 for the bore I5.

The removal of the casting shell Hi from the arbor is effected by jarring or knocking it loose; this simultaneously shears or cuts the slug l1 free from the core 20 and the sidewall l4, and upon further withdrawal of the arbor the slug l'l drops out of the air vent I6 as shown in Fig. 3, leaving the arbor ready for another slush molding step.

The lead shell is then ready for the casting step, in which process the cavity 2| is filled with liquid resin; then the lead shell and its viscous resin contents are stoved, being heated at such a temperature and for such a period of time that the resin sets or cures to a permanently hardened state to form a body such as that shown at 22, Fig. 4, with a central opening 23 extending part, of the way up into the body.

The venting of an arbor as disclosed herein permits the making of complicated molds with cores of any definite length or shape; such cores conform perfectly to the bore of the arbor without the formation of protuberances as heretofore,

which protuberances, moreover, frequently necessitated clipping in order to 'providea smooth molding surface for the casting resin. The

process and apparatus of this invention enable an operator to make cast resin articles having cores of a definite and predetermined length with equal if not greater ease than was possible with the processes heretofore used and which invariably resulted in cores of non-uniform length.

It is to be understood that the invention may be variously otherwise embodied and that the disclosure herein specifically described is merely illustrative and not limitative of the invention except as defined in the claims.

What is claimed is:

l. The method of forming a cored mold by slush-casting which comprises dipping into a bath of molten metal an arbor having a longitudinal casting surface, a bore extending longitudinally and partially through the arbor and a laterally directed vent in the arbor connecting the bore with the longitudinal surface of the arbor whereby the molten metal coursing through the bore rises therein and into the vent to discharge gases therefrom, said metal freezing on the surface of the arbor and in the bore thereof, removing the arbor with the adhering metal from the bath, and withdrawing the arbor from the mold with its integrally formed core formed by the metal adhering to the arbor, said arbor simultaneously cutting and removing the metal slug filling the vent from the mold by its withdrawal.

2. The method of forming a cored mold by slush casting which comprises dipping-into a bath .of molten metal an arbor having a longitudinal casting surface, a bore extending longitudinally and partially through the arbor and a laterally directed vent in the arbor tapered to broaden outwardly from the bore and connecting the bore with the longitudinal surface of the arbor whereby the molten metal coursing through the bore rises therein and into the vent to discharge gases therefrom, said metal freezing on the surface of the arbor and in the bore thereof ,'removing the arbor with the adhering metal from the bath, and withdrawing the ,arbor from the mold with its integrally formed core formed by the metal adhering to the arbor, said arbor simultaneously cutting and removing the metal slug filling the vent from the mold by its withdrawal.

3. An arbor for forming a hollow shell castin mold with an integrally formed core extending into thc'casting space, the arbor having a longitudinal casting surface, a bore extending longitudinally and partially through the arbor and corresponding to the core of the mold to be formed, and a laterally directed vent connecting the bore with the longitudinal surface of the arbor.

4. Anarbor for forming a hollow shell casting mold with an integrally formed core extending into the casting space, the arbor having a longi-v tudinal casting surface, a bore extending longitudinally and partially through the arbor and corresponding to the core of the mold to be formed and a laterally directed vent tapered to broaden outwardly from the bore and connecting thev bore with the longitudinal surface of the arbor and determining the height of the core.

F'INLEY F. ELLIINGWOOD. STEPHEN A. MRAZ.

Images