US1308156A - amick - Google Patents

Description

0.1. AIVIICK.

MOLD.

APPLICATION FILED APII.2. 191'9.

Patented July 1. 1919.

C. J. AMICK.

MOLD.

, APPLICATION FILED APR.2,1919.

l 308, l 5 6 i Padaelflied July l, 1919.

3 SHEETS-SHEET 3.

llillh i JLU PATENT onine.

CLIR JT. ICR, 0F CLEVELAND, OHIO, A-SSIGNOR' T0 THE ALUMINUM CASTmGS COMPANY, F CLEVELAND, OHI, A CORPORATION 0F OHIO.

MDLD.

nacen.

Specification of Letters Patent.

application inea April a, 1919. semi no. atenta.

To all whom t may concer/n. i

the following is a specification, reference y being had. therein to the accompanying drawings.

'llhis invention'relates more especially to an improved form of gate for molds. Whilel the invention, with respect to some of 'its features at least, is of general application, it has been developed in connection with molds for casting aluminum alloy internal combustion engine pistons and is especially applicable-to the casting of cup-shaped and hollow cylindrical articles from metals or metallic Valloys having relatively high crystallization shrinkages, such as characterize 'the aluminum alloys.

One ofthe objects of the invention is to avoid the formation of blow holes in the casting due to the occlusion of air or other gases.

Another object of the invention is to avoid porosity and cracks in the casting due to crystallization shrinkage.

A. further object. is to provide a form of gate, which in addition to preventing blow holes in the castings as above stated, will prevent the passage of gases, metallic oxids l and other impurities into the casting cavity.

Another objectof the invention is the ro-V visiOn of a mold adapted to attain the oregoing objects and at the same tlme be relatively compact in form and correspondingly i limited in weight.

@ther objects more'or less incldental to those above stated Will be' apparent from the following descri tion in which I set forth a preferred em odiment of the invention.

ln the drawings, g y vFigure 1 is a top plan view ofa mold provided with my improved form of gate.

Fig'. 2 is an enlarged fraentar'y section Ontloe line 2 2, Fig. l..4 i lFig. Sis an4 nlar'ged yvertical section on 'the l1ne3 3, l..

sections on the lines 8 8 Y ber.

Fig. 4- is an enlargedfragmentary vertical m @F5 is a horizontal aaien on the une' n" i.; t .MH Y V Fig. 6 is a horizontal section on the line 6 6, lFig. 3. j

Fig. 7 is a section on the broken: line 7 7, Fig. 3'.

Figs. Sand 9 are fragmentary horizontal and 9 9, respectively, Fig. 3. i

The constructionillustrated in the drawings shows my improvements embodied in a permanent mold designed for the casting of aluminum alloynternal combustion engine pistons of relatively large size. Referring in detail to the construction illustrated, the mold as showin comprises aplurality of parts ada-pte 'edwben assembled to form a mold cavity,

A, for the piston casting proper. 'llhe mold body includes a base member l and two come plementary chambered side members 2 and 3 which are movable on the base to and from each other and thus provide for the removal of the castings in the operationofthe mold. These three main sections of the mold body are preferably made of cast iron.

.conveniently be moved to andA from operative position on the base.

The inner side Walls 4 of the complementary members of the mold body mutually engage with each other when said members are moved together as shown in Fig. 1. The Wall 4'is formed between its ends with a semi-cylindrical portion 4, andthe lower parts of the two semi-cylindrical walls t, together with the cylindrical side Wall lES in the base, form the upperside wall of the castingcavityv proper, the bottom of said cavity `being formed by the conical bottom wall l of the depression in the base inemu Said conical lwall is formed with a central depression 1c which rovides for a workspot on the head of t e piston casting. The bottom wall of this central deprcrs "y sion is formed by a plug l", which is grocved onits 4pcnplmry to provide vente for air and other Patented July l, f9f9.

bers 2, 3. These cooperating shoulders 12 and 12, are struck from the same axis and thus serve to effect perfect alinement of the side members in relation to each other. To insure the proper angular positioning of the side members on the base. 1, the latter is provided with upstanding dowel pins 13.

which engage semi-cylindrical recesses 13a in the side members 2, 3.

The mold is provided with a main core 14 which is preferably made of steel and is of the five part form shown in Figs. 13 to 19 of United States Letters Patent No. 1,296,597 to FredericA. Parkhurst, and is of the same general character as the core .shown in the United States Letters Patent to Joseph H.- Bamberg No. 1,296,588. For a detailed description of the core parts reference may be had to said Letters Patent. For thev purpose of the present application it-will suice to state that the core comprises a central part 14, and two pairs of mem- J, bers 14h, 14c and 14, 14e, which when assembled are adapted to be supported at their upper ends in the mold body so as to depend within the cavity formed therein and form 'y the'i'nner walls of the casting cavity proper.

The main core'parts areA supported in the mold body by engagement with a pair of' linersl, 15 which are suitably secured` to the mold members 2,3, as by screws 15a. Thelower ends of the liners serve to form the annular top Wall of the mold cavity. With the. main core parts supported in the liners 15, as shown in Fig. 2, the mold cavity takes substantially a cupshape corresponding to the trunk or skirted piston which it is desired to cast.

To insure proper annular positioning of the core 14 in the mold body, the central member 14a of' the core is provided with a key 1 6 which projects from the core and is received between wear plates 17 secured in slots in the mold members 2, 3 and their liners 15, 15.

rlfhe core members 14b and 14c are shaped to form a recess 14g to provide for a wrist pin boss on the casting, while the members 14d and 14e are shaped to form a recess 14h, for a similar purpose.

The core 14 is provided with vent passages as follows: The middle part 14a of the core is formed on its opposite flat faces with longitudinal passages 141314k each of which extends from the upper end of the core part to a transverse passage 14n near the lower end ofthe core part. I Thenthese. Hat faces of the core part are formed at their lower ends with a series of vent grooves 14, extending from the botten; surfacevof' the core upward to the transverse passage 14m, and an adequate vent upward through the c ore is thus provided for air and gases collectlng on the bottom surface of the core. Each of therunners 15 is formed with vent , grooves 15, 15C, 15d and 15e on its bottom, inner, outer and top sides, respectively.

18, 18 are removable core pins slid'ably mounted in the mold members 2, 3 with their inner ends projecting into the boss recesses 14g, 14h. To facilitate their removal, said pins have their ends slightly tapered where they engage the mold body and project into the mold cavity.

In the operation of the mold the various parts are secured in operative position by lock devices 19, 19 each of which comprises a pin 19a mounted on one of the side members of the mold and a coperating pivoted hook 19b on the other side member.' When the side members 2, 3 are brought together in proper position on the base l, the hooks 19b are forced down over the pins 19a so that the parts of the mold body are firmly secured together.

I turn now to a descriptionof the gate of the mold to which my improvements more particularly relate. The gate which is formed by alining recesses in the adjacent walls 4, 4 of the mold members 2 and 3, and in the base 1, in its entirety comprises a feeder and a supply conduit. The feeder is in the form of an upright cavity 20 adjacent one side of the casting cavity and extending from the bottom of the casting cavity upward to and above the upper end of said cavity, the upper part of the feeder compprisinga riser' 20a extendingwell above the top of the casting cavity. The feeder communicates with the casting cavity through a short passage 21, said passage extending, preferably, continuously from the bottom to the top of the feeder and being relatively narrow in comparison with the greater width ofthe feeder cavity.

The main part of the feeder cavity is formed by recesses in the walls 4, 4 of the mold members, but the lowermost end thereof is formed by a recess 22 in the mold base. The main part ofthe feeder 2O is formed opposite the casting cavity and the passage 21 leading thereto, with a downwardly and laterally inclined wall 20". At its lower end the inclined wall 20b joins the inclined wall 22a which leads to the bottom of the casting cavity.

The adjacent faces of the mold members 2 and 3 are formed with vent grooves 23 extending from the top of the feeder chamber 20 to the upper surface of the mold.

The supply conduit of the gate comprises a downwardly extending inlet section 24, a laterally and upwardly extending liquid seal section 25, and a downwardly and laterally extending discharge section 26 which opens lll into the top of the feeder cavity 20. At 27, where the inlet section 24 joins the liquid seal section 25, the supply conduit is sharply constricted. 'lhis constriction of the passage and the abrupt change ofdirection serve to strongly check the velocity of the entering molten metal. -As the entering metal rises in the supply passage to a level above the point 28 ot the upper wall of the passage, a liquid seal is formed so 'that any'l oXids or other impurities lighter than the metal will Heat upon thesurface of the metal in the inlet section 24 and be prevented from passing throughto the feeder and the casting cavity proper. @bviously this liquid seal will tend to prevent the passage of air with the entering metallo l f Y f lt will be observed that the discharge sec tion 26 of the supply conduit of the gate is formed and arranged to deliver the molten metal into-the topk of the feeder cavity( on lines substantially parallel to the inclined wall 20" thereof, thus directing the stream ot metal smoothly downward over said wall in a manner to avoid agitation and splashing.

llt is usually desirable to provide for heating the body of the metal to maintain it at a suitable temperature and ll have v'shown burners 29, 29 mounted on brackets 30, 30, said burners bein arranged so that their dames are directe through openings *9**V in the plates 9 to heat the inner walls of the mold members 2 and 3, and especially the parts ot the walls 4in which the gatefis formed-'this arrangement insuring that the metal in the-gate shall remain molten longer than that in the mold proper.

Preferably the walls of the mold, including core parts, which constitutethe walls for the mold cavity are suitably coated or treated in well known manner -to reduce as much as possible agitation of the molten metal as it Hows into contact therewith and to insure proper setting of the metal within the cavity. y

vlin the operation ofthe mold above dscribed the members 2 and3 are first moved a into operative position on the base 1, then the sections of the main lcore 14 are inserted, the lookin tightly loc the moldmembers 2 and 3 together andv rmly, clamp the main core in position. flinally the core pins 18 are introduced,

'lhe temperatures at which the various parts are maintained will depend largely upon the nature yoi the metal or alloy to be cast. Assuming that' the burners 29 have been operated to heat the mold parts to the desiredltemperature the mold is now ready to receive the molten metal.` Said metal is brought to the mold in any suitable manner,

as by ladle, and is pouredA into the in1et24 of.

the gate. The sharp constriction of the gate passage at 27 strongly retards the velocity of` devices v19 are driven home to and castin the entering metal as does also the lateral and upward direction of the liquid seal section 25 oit the passage into which the metal passes from the inlet section. @n account of this marked retaiding of the How the l'liquid seal section 25 of the gate passage quickly lls and the metal backs'up more or less inthe inletsection 24, thus forming .an effective liquid seal at the point 28, which tends to prevent the entrance of air along with the metal and also insures that anyl oXids or other impurities lighter than thev metal will Hoat up on the surface of the metal in the inlet section 24 of the gate. 'As' the metal backs up in the inlet section 24, it also passes over into the discharge section 26 of the gate smoothly and there is an entire, absence of` any localiz'ed impactof the enterin stream oit metal either against the outer wal s pf the castin cavity or against the core parts:l

As t e molten metal continues to flow into the mold and its upper-surface, in the castin cavity, comes into contact with the lower en of the core 14, the air above the metal either finds its way radially tw ard and into the annular part of the cavity in which it is free to rise and escape through vent grooves 15", 15, 15d and 15e formed in the liners 15, or, entering the vent grooves 14, iinds its way upward through the core the exterior of the mold. y

. ing the relatively quiescent mass -of rising metal is readily edected in the manner just described, it is to bel observed that if there were splashing or agitation ofthe metal in the mold, air or gas would be occluded in it and it would be practically impossible to separate such air or gas, no matter how adequate the provision for venting might be'.Y and such occlusion of air or gas would, of course, resultin serious porosity of the casting. This has been found. to (be especially true in the case of castings having heavy cross sections.

As the molten metal rises in the feeder cavities,v it continues to liow from the ceder cavity through the short narrow passage 21 into the annular section ofthe .casting cavity passing aroundV the main core in both dirctions, as will readily be understood. jDuring this part of the pouring the .entering ,metal continues to be iasl 2()v 4 the molten metal gives up its heat to the directed smoothly downward `over the inclined wallA b of the feeder and thence smoothlyinto the molten bath accumulated in the lower part of the feeder, and in turn there is a smooth flow of the metal from the feeder through the passage 21 into the casting cavity and, as at the beginning of the pouring, the metal enters the casting cavity 'with an entire absence of high velocity jet walls .of the mold and tends to freeze first at points remote from the gate 'or source of supply and then gradually andl progressively from said remote points around the main core of the gate. In my improved mold as the metal freezes in the casting cav- 1ty proper, compensation for the crystallization shrinkage is afforded bythe molten metal which is maintained vin the feeder 'cavity and flows freely at any level through the passage 21 into the casting cavity. In a word, an adequate supply of molten metal 1s maintained in position to enter the casting cavity at any level to compensate for crystallization shrinkage and a progressive v setting of the metal in the mold is secured from points opposite the gate around the mam core in both directions, then in the short assage 21 between the casting cavity and t e feeder and finally in`the feeder itself. y

After a short interval to permit the metal to set, the locking devices 19 are eased oli',

the core parts are withdrawn, the pins 18 somewhat in advance of the main core parts, then the lookin devices 19 are entirely disengaged and t e mold members 2. and 3 separated to permit removal of the casting.

The avoidance, by means of my improved gate, ofany high velocity jet action of the molten metal as it enters the casting cavity has been explained but it may be added that the importance of this lies not only in the fact that it obvia-tes splashing of the metal due to sharpimpact on the mold walls, but

also 1n the avoidance of a localized heating and wear of the mold walls which would result at the points sustaining the impact of the jet. It has been found that. where such jet action occurs in the filling of permanent molds the impact of the hot metal on Athe walls results hoth in serious wear and disintegration thereof and also in a:

4 narrow warping of the parts, especially the core parts, on account of the localized over-heating of said parts.

It will be observed on reference to Fig. 3 that the inlet section 24 of the gate conduit partially overlies the liquid seal section 25 70- while the discharge section 26 of the gate conduit overlies the feeder 20. This compact form and arrangement of the gate parts makes it possible to reduce the hulk of the mold to a minimum for a casting cavity of a given size.

I have shown my invention only in connection with molds for the production of piston castings but it is obviously applicable in the production of castings of other articles and other forms and it will be understood that the foregoing disclosure is for purposes of illustration and explanation and .not intended to define the scope of the invention.

What I claim is:

1. A mold having a cavity for the casting proper and provided with. a gate comprising an upright feeder cavity adjacent the casting cavity and communicating with the casting cavity at. various levels between the bottom and top thereof through a short narrow passage, said feeder cavity having its lateral wall opposite the casti'n cavity inclined downwardly and latera ly toward said casting cavity, and a supply passage extending from the gate inlet opening to the top of the feeder cavity, the discharge end of said supply passage being arranged to discharge the molten metal into the feeder cavity onlyon lines substantially parallel to the inclined wall of said cavity.

2. A mold having a cavity for the casting proper and provided with a gate comprising an upright feeder cavity adjacent the casting cavity and communicating with the casting cavity at various levels between the bottom and top thereof through a short narrow passage, said feeder cavity having its lateral wall opposite the casting cavity inclined downwardly and laterally toward said casting cavity, and a supply passage comprising a downwardly extending inlet section, a laterally and upwardly extending liquid seal section into which the inlet section delivers and a discharge section arranged to receive molten metal from the liquid seal section and discharge it into the feeder cavity only on lines substantially parallel to the inclined Wall of said cavity.

3. A mold having a cavity for the casting proper and provided lwith a gate comprisingan upright feeder cavity adjacent the casting cavity and communicating with the casting cavity at various levels between the 125' bottom and top thereof through a short passa e, said feeder cavity having its lateral. wa 1 opposite the casting: eavity' inclined downwardly and laterally toward said casting cavity, and a supply passage coni rising a downwardly extending inlet section, a laterally extending section into which the inlet section delivers, and a discharge section arranged to receive molten metal from the laterally extending section and discharge it into the feeder cavity only on lines ,substantially parallel to the inclined wall of said cavity.

In testimony whereof, ll hereunto affix my signature.

CLAIR J. AMICK.

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