US2018222A - Mold for casting hollow articles - Google Patents

Description

Oct. 22, 1935. A. B. NORTON MOLD FOR CASTING HOLLOW ARTICLES Filed Jan. 14, 1933' 4 Sheets-Sheet 1 INVENTOR Ans/v B. NoRro/v.

ATTORNEY Oct. 22, 1935. A B, NORTON 2,018,222

MOLD FOR CASTTNG HOLLOW ARTICLES Filed Jan. 14, 1933 4 SheetsSheet 2 INVENTOR Aunv B. NORTON ATTORNEY Oct. 22, 1935. A. B NORTON MOLD FOR CASTING HOLLOW ARTICLES Filed Jan. 14, 1935 4 Sheets-Sheet 3 ALLs/v B. NORTON.

INVENTOR AT'I'O RNEY Oct. 22, 1935. A, a NORTON 2,018,222

MOLD FOR CASTING HOLLOW ARTICLES Filed 1953 4 Sheets-Sheet 4 72 Jzt Z6 27 l W 33 n "J -57 I Y/////V,l

INVENTOR ALLEN 5. Nam-01v AT TOR N EY Patented Oct. 22, 1935 MOLD FOR CASTING HOLLOW ARTICLES Allen B. Norton, Shaker Heights, Ohio, assignor to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Application January 14, 1933, Serial No. 651,662

6 Claims.

This invention relates to a mold for and method of casting thin-walled metal articles. It is particularly adapted to molds for casting articles having relatively extensive wall areas of reduced section thickness.

A familiar example of the type of article to which the invention is applicable is a teakettle, and in this specification and the drawings appended thereto a design of mold is shown for casting a teakettle. The description and drawings are merely illustrative and in no way restrict the invention, since, as will become apparent, the invention may be utilized in the casting of various forms of cooking utensils or other articles of like contour and characteristics.

In the production of objects such as cooking utensils the light metals and their alloys have met with considerable favor. This is particularly true of aluminum and aluminum base alloys, and cooking utensils are made from these alloys in both the cast and wrought forms. For practical and economical reasons some types of aluminum utensils are cast while others are drawn, spun or otherwise wrought to shape. The method of casting in permanent molds, when applied to aluminum articles such as disclosed herein, is simple and economical and presents a number of advantages, such as accuracy of dimensions and ease of duplication, resulting in a casting of finegrained internal structure and adequate physical properties. In addition to these advantages, numerous utensils can be made from one mold and, by using a mold such as disclosed hereinbelow, by-one operator. v

In casting hollow cup-shaped articles in permanent molds a number of operating difficulties are encountered when the casting incorporates fairly extensive areas of low section thickness. This is particularly true when the thin areas are flat and are disposed substantially horizontally in the mold. The entering molten metal is rapidly chilled by the mold walls and may-freeze before the casting cavity is completely filled. The mold or metal can be heated sufficiently to overcome this tendency, but in so doing some of the advantages which accrue from the use of such a mold are lost. A coating of mold wash of sumcient thickness may be applied to the interior of the casting cavity, but although this reduces the heat conductivity of the mold walls and reduces the rate at which the metal freezes, too thick a coating impairs the casting finish and may injuriously affect the dimensional accuracy. Perhaps the principal difliculty encountered in filling out thin, flat areas in permanent molds arises from the tendency of the entering metal to branch out into circuitous paths and entrap air or other gases. In such case, the metal frequently freezes without permitting the gas to escape, and a cavity results which may extend through the wall of-the casting. It is evident that this tendency asserts itself particularly'in the substantially horizontal areas since in vertical sections the metal may force its way to the bottom by gravity and displaces the gas before it 10 towards the top of the mold where it can be conveniently vented.

I have succeeded in designing a mold wherein are retained many of the advantages of an allmetal mold and at the same time I avoid many disadvantages, including those noted heretofore.

It is an object of my invention to provide a casting assembly which is primarily a permanent mold but in which the interior of the casting is cured out, preferably by means of a non-per- 0 manent member such as a green sand core or the like, an additional non-permanent member or green sand core being employed to define part of the exterior of the casting in such a manner that the most extensive flat area of the casting, in the form shown hereinbelow, a kettle bottom, is defined between two non-permanent green sand surfaces.

Another object of my invention is to provide a novel mold construction and method of casting whereby gas or air is permitted to escape freely from the casting cavity and the tendency to severe chilling in thethin sections of the casting is substantially eliminated.

A further object of my invention is the provision of a casting assembly in which non-permanent core members are employed in combination with a permanent mold in such a manner that the major portion of the casting assembly may be used repeatedly in successive casting operations with the replacement only of the sand cores.

Various other objects, including the particular design of my casting assembly which enables particles of sand dislodged from the main core to drop freely and entirely clear of the mold base in such a manner that no interference will be encountered in the subsequent operation of the mold, will obviously present themselves on consideration of the following detailed description not the equal of metal in heat conductivity and consequently in chilling properties, is superior to baked sand in this respect. Green sand is frequently used in a finer granulated condition than is dry sand and this results in a smoother surface finish on the casting. In molds within the scope of the present invention, however, dried sand cores may be used, and one of the advantages of my invention is that the advantages accruing from the use of green sand are also available.

A thorough understanding of my invention will .be obtained by reference to the particular embodiments thereof described in detail hereinbelow and illustrated in the appended drawings, in

Fig. 6 represents a fragmentary view taken on the line VI-VI of Fig. 5.

Referring to the drawings, casting assemblies are illustrated which embody the principles of my invention and which are adapted to the formation of a cast teaket'tle having a substantially horizontal bottom It, a continuous side wall I I, which in the present example is polygonal in form, and an integral spout |2, bosses l3 and I4 being pro vided on the kettle adjacent its open top l5 for the purpose of attaching a suitable handle thereto.

' The casting assembly illustrated in Figs. 1, 2, 3 and 4 comprises a suitable base member l6 supported and secured as by cap screws H in overhung relationship upon a bench or table l8. By this method of mounting the base 5 a substantial portion thereof extends beyond the bench l3, the purpose of which will be hereinafter understood. Secured as by cap screws I9 to the base member, and at one end thereof, is a pedestal bracket which incorporates at its upper end a suitable bearing 2| within which a hinge post or bolt 22 is mounted by means of a pin 23 extending through the bolt and bearing upon the upper surface of the bearing 2|. The lower end of the hinge bolt is guided within a suitable aperture or hearing 24 located in the base l6 and aligned with the aforementioned bearing 2|.

Pivotally mounted upon the hinge bolt 22 for rotational movement with respect to each other and to the base member I6 are a plurality of mold sections which in the present invention consists of two pairs of cooperating mold sections 25 and 26. The mold sections are provided with angle brackets 21 suitably secured thereto as by means of cap screws 28 and have formed integral therewith hinge bosses 29 which are provided with suitably aligned hearings or bores through which the aforementioned hinge bolt 22 extends. Easily replaceable ferrous metal bearing washers 30 or the like surrounding the hinge pin 22 and disposed between certain of the adjacent bosses 29 reduce the friction attendant the opening and closing of I the mold sections and insure a definite spacedrelationship between each mold section for any radial position of the same. Alsov a like bearing washer 3| mounted similarly to the washers 33 but positioned between the lowermost hinge boss 29 and a suitable upstanding machined boss 32 on the base i6 supports the mold assembly an appreciable distance above the base l6, which construction reduces thefrictional resistance between the bottom mold sections and the base over a substantial portion of their adjacent faces. 5

tour of the article to be cast.

A core-supporting plate-34 is positioned adjacent the overhung end of the base l6 within a 20 suitable bore or aperture 35 formed in the base. This core-supporting plate is provided with a downwardly depending pin 36 for the purpose of aligning the core-supporting plate with respect to the casting cavity, the pin 36 being guided be- 25 tween horizontally extending pins 31 projecting from the foremost portion of the base H3. The plate 34 has formed integral with its upper surface a pilot member 36 in the form of an annular shoulder and the lower mold sections 25 are ma- 30 chined to provide: an annular cavity 39 the wall of which,.when the lower mold sections are in their closed position, coincides closely with the pilot member 38 and the top surface of which bears upon the upper surface 40 thereof. Ac- 5 tually the only appreciable frictional contact between the lower pair of mold sections 25 and the base I6 is encountered on the flat surface 49 of the pilot member 33 and between the washer 3| and boss 32.

The core-supporting plate 34 is provided with an annular opening 4| concentric with the bore 35 in the base plate and the annular bore or aperture 4| is provided with a plurality of annular grooves 42 within which a green sand core 43 is suitably secured. The core 43 extends upwardly into the cavity formed by the cooperating mold sections 25 and in the present instance represents the interior contour of a cast teakettle. To this end the overhung portion of the core 43 which cooperates with the mold sections to form the interior of the spout I2 is supported upon a suita ble insert 44 secured to the forward end of the core-supporting plate 34.

The upper pair of mold sections 26 are centrally positioned with respect to the lower mold sections 25 by means of forming the upper or top surface 45 of the lower pair of mold sections 25 with a shouldered portion in the form of a centering ring or pilot member 46. On the top surface of the pilot member 46 a second sand core-supporting member, in the form of an annulus 41, is supported by means of a flange 48 formed integral therewith. The core-supporting annulus depends downwardly into suitable cooperating apertures 49 in the lower pair of mold sections 25, whereas the flange 48 extends upwardly into cooperating apertures 50 in the upper pair of mold sections 26. Within a centrally disposed bore or aperture 5| in the core- 7 supporting ring 41, the interior surface of which is provided with a plurality of grooves 52, an upper sand core 53 is suitably secured. By means of this construction the relatively extensive, substantially horizontal bottom surface i0 of u cavities 58.

,53 and the side walls of .cpair of mold sections,

the teakettle is defined by two non-permanent or sand surfaces.

In the preferred form of my invention molten metal is conducted into the casting cavity by .means of a two-way or compound gating means comprising acommon inlet passage 55 and discharge passages 54 which extend outwardly, upwardly and downwardly to meet suitable feeder This gating arrangement provides a liquid seal when molten metal is introduced into the inlet 55, which prevents the metal from entering the mold in a broken or agitated stream and thereby prevents the production of interior castings. Reduced sections 51 between the risers I the cast article control the flow of molten metal into the casting cavity.

In the operation of my improved form of casting assembly, ,with the mold sections open, as shown in dotted lines in Fig. 1, the core-supporting plate 34, together with its integral sand core 43, is set in place within the cavity in the base Ii. Thereafter the bottom pair of mold sections 25 are closed, a tapered pin 58 provided in one of the mold sections being adapted to center within the tapered bushing 59 provided within the adjacent mold section, thereby insuring proper alignment of the bottom pair of mold sections. A mold clamping device comprising a link member 60 pivotally mounted as by means of a bracket GI and pin 62 to one mold section and provided at its opposite end with a cam lever 63 adapted to be brought into clamping relationship on a suitable clamping plate 64, which extends from the opposite member of the bottom insures means for clamping the bottom pair of mold sections 25 into close contact and metal-receiving arrangement.

With the bottom pair of the mold sections in closed position the upper sand core-supporting ring 41 is set in place upon the pilot member 46. Openings 65 are provided at diametrically opposite points on the top surface of the lower pair of mold sections, the openings extending downwardly into the upper surface thereof. These openings permit the necessary clearance for the fingers of the operator in setting the ring 41 in place, and eliminate the possibility of displacing any of the sand constituting the core 53. With the upper sand core 53 in place, the

.mold sections 26 are brought into closed position and clamped therein by means of a suitable cam lever 66 pivotally mounted on the link 61, which, as in the case of link 60, is pivotally secured to a bracket 68, the cam lever being adapted to be brought into clamping relationship on a suitable plate 69.

With the mold in its above-described closed position, molten metal introduced through the entrance 55 courses simultaneously through the runner cavities 54 to diametrically opposite points in the casting cavity and eventually fills the mold. Gases generated during such a pouring operation percolate through the green sand cores and are permitted to escape through the upper surface of the sand core 53, and thence through the vents 10 provided in the top surface of the mold sections 26. The flange 43 of the upper sand core-supporting member 41 may be chamfered as at II and otherwise be formed slightly thinner than the depth of the cavity 50, thus providing a gas-collecting cavity or ring around its upper periphery within which a portion of the evolved gases may collect.

The arrangement whereby the relatively flat surface i0 is supported between the faces of the sand cores 43 and 53 insures the elimination of gas inclusions in this relatively flat surface of thin cross-section.

On completion of a casting operation it is merely necessary to release the clamping mem- 5 bers 63 and 86, swing the mold sections open by means of the handles 33, and remove the cast article with its integral interior core 43 and the gate metal attached to the exterior thereof. The internal sand core 43 is shaken or otherwise removed from the interior of the cast article and the gate metal is also suitably removed. It is important to note that the mounting of the casting assembly in overhung relationship with respect to the table or bench I8 permits loose sand 15 dislodged from the interior sand core 43 to drop freely into any suitable container below the aperture 35. Such construction eliminates the collection of sand or the like on the mold base,

which might hinder the subsequent operation of 20' the apparatus.

In the embodiment of my invention shown in the fragmentary views in Figs. 5 and 6, the casting assembly is essentially the same as thatshown in Figs. 1, 2, 3 and 4, and the same refer- 26 ence numerals have been employed to represent like parts of both casting assemblies.

The essential difference in the two casting assemblies lies in the gating arrangement wherein the simplest form of gate, comprising a single 30 molten metal-introducing passage I2, is employed. In this arrangement the mold is assembled in a manner similar to that described in connection with the preferred form of my invention, and the metal is introduced through the passage 12 directly into contact with the top surface of the internal core from where it courses downwardly into the lower extremities of the casting cavity, during which procedure the gases evolved are permitted to percolate through the 40 sand cores and through the vents Ill to the atmosphere.

While I have shown particular embodiments of my invention, it will be understood that the invention is not limited thereto but may be em- 45 bodied in numerous other constructions within the spirit and scope of the following appended claims.

What I claim. is:

1. A casting assembly comprising, in combi- 50. nation, a mold base mounted in overhung relationship with respect to its support, a core-supporting plate having a pilot member associated therewith mounted on said base, said pilot member being positioned in proximity to the over- 5 hung portion of the base, a hinge bolt mounted on said base, a pair of cooperating mold sections mounted on said hinge bolt and supported in spaced relationship with respect to the mold base, a second pair of mold sections mounted on 69 said hinge bolt in slidable contact with said firstmentioned pair of mold sections, both pairs of mold sections being capable of rotatable movement into and out of operable contact with each other and recessed on their adjacent contacting faces to partially define the exterior contour of a casting cavity, said first-mentioned pair of mold sections being recessed to embrace the aforesaid pilot member whereby the casting assembly is properly aligned, a sand core replaceably 70 mounted within said core-supporting plate and extending into said recessed mold sections to define the interior contour of the casting cavity, said core being positioned in a manner to permit particles of sand dislodged therefrom to fall II 'evolved during a casting operation clear of the casting assembly, and a second sand core supported on said first-mentioned pair of mold sections and enclosed in recesses formed in said second pair of mold sections, said second sand core cooperating with said first-mentioned pair of mold sections to define the exterior contour of the casting cavity in entirety, and a plurality of vents extending through said secondmentioned pair of mold sections into proximity with said second sand core.

2. A casting assembly for casting metal articles comprising a mold base, a core-supporting member positioned in said mold base, asand core disposed in said supporting member and defining, in entirety, the interior contour of a casting cavity, permanent mold sections movably mounted on said base to move into and out of operable contact with one another, said permanent mold sections being adapted to support and enclose a core-supporting member having a second sand core secured thereto, said permanent mold sections and said second sand core cooperating with each other to define the exterior contour of said casting cavity, and a gascollecting cavity provided adjacent said second sand core and between it and the cooperating mold sections, wherein a portion of the gases may be collected.

3. A casting assembly for casting metal articles comprising a mold base, a core-supporting member positioned in said mold base and provided with core-aligning means, a sand core disposed in said supporting member and defining, in entirety, the interior contour of a casting cavity, permanent mold sections movably mounted on said base to move into and out 01' operable contact with one another, said permanent mold sections being adapted to support and enclose a core-supporting member having a second sand core secured thereto, said permanent mold sections and said second sand core cooperating with each other to define the exterior contour of said casting cavity, a gas-collecting cavity interposed the second-mentioned sand core and permanent mold sections, vents connecting said gas-collecting cavity to atmosphere, and mold-aligning means associated with said permanent mold sections and adapted to engage the first-mentioned core-supporting means to provide alignment of the casting assembly.

4. A casting assembly for casting metal articles comprising a mold base, a pair of cooperating mold sections movably mounted on said base for movement into and out of operative contact with each other, a second pair of mold sections mounted in slidable contact with said first-mentioned pair' of mold sections, said second pair of mold sections being similarly capable of movement into and out of operable contact with each other, said first-mentioned pair of mold sections being recessed on adjacent contacting faces to partially define the exterior contour of a casting cavity, a sand core replaceably mounted on said base and extending into the cavity in the firstmentioned pair oimold sections to define, in

entirety, the interior contour of the casting cavity, and a second sand core replaceably mountedi upon the first-mentioned pair or mold sections and adapted to cooperate with the first-men- 5 pivotally mounted on said base and capable of being rotatably moved into operable contact with 15 each other, a second pair 01' mold sections pivotally mounted above and on said first-mentioned pair of mold sections and capable of being ro' tatably moved intooperable contact with'each other and with the lower pair of mold sections, so

all of said mold sections being recessed on their adjacent contacting faces to partially define the exterior contour of a casting cavity, pilot mem-' bers provided on said base and the upper surface of said lower pair of mold sections adapted II:

to cooperate with recesses in said lower pair 01' mold sections and said upper pair of mold sections respectively when in operable contacting position to align the same, a sand core supported on-said base and projecting into said lower pair I0- of mold sections to define the interior contour of the casting cavity, a sand core supported on said upper surface of the lower pair 01' mold sections and cooperating therewith to complete the exterior contour of said casting cavity, a gas- I.

collecting cavity in said upper pair of mold sections adjacent said last-mentioned sand core, and a plurality of vents from said gas-collecting cavity to the atmosphere.

6. A casting assembly for casting cup-shaped 0 metal articles, said casting assembly comprising a mold base, a hinge bolt mounted on said base and supporting a plurality of mold sections, said mold sections being rotatably movable into and out of operative contact with each other and 45 having their adjacent contacting faces recessed to partially define the exterior contour of a casting cavity, means for supporting said mold sections in spaced relationship with respect to said base member, a core-supporting member mounted 60 on said base and supporting a sand core, said sand core extending into said recessed mold sec tions to define, in entirety, the interior contour of said casting cavity, and a second sand core associated with said mold sections and first- 55

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