US2660770A

US2660770A - Casting apparatus

Info

Publication number: US2660770A
Application number: US183363A
Authority: US
Inventors: Ralph P Davis
Original assignee: Walworth Co
Current assignee: Walworth Co
Priority date: 1950-09-06
Filing date: 1950-09-06
Publication date: 1953-12-01
Anticipated expiration: 1970-12-01

Description

Dec. 1, 1953 R. P. DAVIS CASTING APPARATUS Filed Sept. 6, 1950 INVENTOR. Bav/i I. Dal/61s. BY WM Patented Dec. 1, 1953 CASTING APPARATUS Ralph '1. Davis, Squantum, Mass, assignor "to Walworth Company, Boston, Mass., a corporation of Massachusetts Application September 6, 1950, Serial No. 183,363

Claims. .1

This invention relates to casting apparatus and method and more particularly to metal pouring apparatus and method for use with shell-type molds.

Molds of the thin walled shell-type are comprised of a major portion of an inorganic molding material, such as, sand, and a minor portion of a component serving to bind the inorganic material. The completed molds are in two or more matching parts having the form of hard thin shells of substantial strength. The inner faces ofthe matching parts are smooth. and finished whereas the outer surfaces are left in a rough and irregular condition. Consequently, during the casting operation using such molds the, common weighting methods for ordinary sand molds cannot be used with any degree of success.

In casting operations using shell-type molds it has been customary to embed the mold parts in a loose, relatively coarse granular material with the intention of enabling the mold to withstand the static pressure of the molten metal. Refractory materials such as steel shot, sand and gravel have been proposed as suitable bedding material to be contained in the pouring box. This expedient does not, however, provide uniform pressure on the mold parts and in some cases is considerably less than the pressure exerted by the molten metal. The resulting separation or distortion of the mold parts during the casting operation causes sufiicient nonconformity between the pattern and the casting to render the latter completely useless. Consequently, the desirable features of the shell-type mold have been outweighed by the difliculty of producing satisfactory castings with such molds.

An object of the present invention is to supsupport shell-type molds during the casting operation under substantially uniform pressure throughout the area thereof and suflicient to prevent separation or distortion of the mold parts. Another object of the invention is to adjust the pressure on the molds in order to approximate or exceed the static pressure of the metal poured into the mold.

Another object of the invention is to remove the supporting material from the pouring box in an expeditious manner after the casting operation.

The apparatus and method for accomplishing these and other objects and advantages of the invention comprises a pouring box of sufficient dimensions to contain a complete mold in a vertical pouring position. The box is lined on opposite sides with a flexible material, such as a rubber diaphragm, providing a space between the liner and the adjacent wall into which fluid under pressure may be admitted. Thus, the diaphragm becomes distended toward the mold from eachside and contacts the approximate area thereof with a uniform pressure which may be as great or greater than the static pressure of the casting material to be poured into the mold.

In order to protect the diaphragm from the heat of the mold an intermediate material may be used such as steel shot, sand or gravel. This material is poured into the space between the mold and the diaphragm with the mold located approximately midway between the opposite sides of the pouring box. The fluid pressure on the diaphragms is thus transmitted through the m termediate material to the molds without losing any advantages of this invention.

The intermediate material may be easily removed from the box after the casting operation by the use of fluid pressure or suction applied to the bottom of the box at the appropriate time. The box may be specially formed to facilitate the shot withdrawal even when the box is completely full.

In the accompanying drawings:

Fig. 1 is a plan view of the metal pouring ap paratus showing a mold in position therein;

Fig. 2 is a cross-section taken on the line II-II '2 Of Fig. 1;

Fig. 3 is a longitudinal section taken on the line III-III of Fig. 2, and

Fig. 4 is an enlarged sectional view taken on the line IV-I'V of Fig. l.

Referring more particularly to the drawing, the pouring box 9 comprises a generally rectangular casing Ill having an open end [2 and a centrally disposed, hollow-partition 14. The partition it serves toudivide thev casing i=8 longitudinally into two halves, each of which. is adapted to contain a mold. As indicated in Fig. 1 by a broken line 16 a shell-type. mold comprised of two matching parts is positioned in one of the halves of the pouring box. It will be apparent that a similar or diiferent mold could be positioned in the other half of the casing it. Moreover, while a double pouring box is shown and described herein, a single box could be used if desired. The length and width of the casing in as viewed in Fig; 3 are greater than those of the mold it which is inserted freely in an edgewise direction through the open end I 2. It will be observed that the depth of the casing ill on each side of the .parti tion 14, as viewed in Fig. I, and defined by the. opposite side walls of the casing [l0 and partistain is sufficient to space these walls from the molds It. An aperture i9 is provided preferably at one end in each of the side walls of the casmg l0 and the partition I4- respectively-for a purpose apparent hereinafter.

Each half of the pouring box- 9 contains a pair of liners :20 of generally rectangular form which are secured at their'marginal edges to the adjacent side walls. of the-casing I0 and partition [4 respectively. The securing means for the liners may take the form of rivets 22, although bolts or other securing means may equally well be used. The liners 24 are preferably made of flexible sheet material, such as rubber, although any other resilient or elastic material may be employed. the liners 20 and the adjacent walls of the casing I0 and partition I4 is an annular spacer or gasket 25 of rubber or similar resilient material. A retaining ring 28, preferably of metal or other hard material, is superimposed on each of the liners 22 to provide a firm surface for the rivets 212. In this manner, the liners 22 are spaced from the adjacent walls of the casing I0 and partition M to provide four chambers 24 which are sealed around the edges by the fastening means described to close the chambers 24 thus provided. A plurality, in this instance four angle bars extend transversely across each half of the pouring box 9 opposite the open end I2 and may each be secured at one end to the side walls of the casing I6 and at the opposite end to the partition I4 by welding or other suitable means. As shown more clearly in Fig. 3 each'of the angle bars has the open portion of the angle facing away from the open end I2 of the pouring box 9, thus presenting a pair of inclined surfaces toward the open end I2. As will be apparent, the mold I6 may be positioned on the angle bars #30 in pouring position and supported thereby during subsequent operations.

Closure means 32 in the form of an elongated, funnel-shaped member is provided for the end of the casing opposite the open end I2. The closure means 32 conforms to the side and end walls of the casing I0 and may be integral with these walls as shown or may be formed as a separate part secured thereto if desired. The closure means 32 has an outlet 34 in the form of a slot extending longitudinally of the neck of this funnel-shaped member. An exhaust pipe 36 extends longitudinally of the closure means 32 and is provided with an elongated recess 38 for the reception of the outlet 34. Preferably, the walls of the recess 38 are welded or otherwise secured to the side walls of the closure member 32 with the outlet 34 positioned substantially coincident with the axis of the pipe 36 for a purpose apparent hereinafter.

Means for admitting fluid under pressure to the chambers 24 are provided and take the form of a plurality, in this instance four, elbows 40 one pair being secured as by welding to the exterior side walls of the casing III on opposite sides thereof and the other pair located within the hollow partition I4 for communication with the apertures I9 in the side walls. The elbows 40 connect with suitable piping 42 which communicates with a source of fluid pressure (not shown), such as compressed air, through a multi- Way valve 44 having an inlet 46 and an exhaust 48 associated therewith. In order that the pressure admitted to the chambers 24 may be set to a desired value, a suitable pressure regulator 50 may be included in the inlet 46 for this purpose. It will be understood that separate valves 44 can be provided to control the flow of fluid in the piping 42 to each half of the pouring box 9- or a single valve 44 may control the flow to both halves.

In order to protect the flexible liners 20 from the heat of the molten metal transmitted through the mold l6, an intermediate material is used between the liners 20 and the mold I6. This material is of a granular nature such as Interposed between each of steel shot, sand or gravel and is pourable through the open end I2 after the mold I6 is positioned in the casing I0. As shown in Fig. 1, the mold I6 is located approximately midway between the liners 20 in one-half of the pouring box 9 and the granular material, indicated by the reference numeral 52, completely fills the surrounding space. It will be apparent that the closure means 32 will also become filled with the granular material 52 and will flow from the outlet 34 into the pipe 36. However, since the outlet 34 is positioned substantially coincident with the axis of the pipe 36 then the latter will not be completely blocked by'the granular material even when the casing I0 is completely filled. In some cases it may be advantageous to insert a rigid plate of metal or other suitable material between the flexible liners 2D and the granular material 52 depending upon the type of mold I6 which is to be poured. Moreover, water or other liquid or gas may be used to fill the chamber 24 if desired.

The casing I0 is provided with a plurality, in this instance four, locating lugs 54 one at each corner and suitably perforated to receive retaining bolts or the like (not shown) by means of which the casing may be secured to a foundation, as indicated by the broken line 56 in Figs. 2 and 3. When so positioned, the closure means 32 and the pipe 36 may be contained in a pit or other depression 58 in the foundation 56 below the securing means for the pouring box 9.

OPERATION In the operation of the apparatus, the mold I6 may be inserted edgewise into one of the spaces in the casing II! between the side wall and the partition i 4. As previously noted, the bottom edge of the mold rests on the angle bars 30 and is positioned approximately midway between the partition I4 and the side wall of the casing I0 and spaced from the end walls thereof. While so positioned, the space around the mold I6 is filled with the intermediate material such as steel shot, which will serve to support the mold I6 in the desired location. Thereafter, fluid under pressure is admitted by operation of the valve 44 to the chambers 24 on each side of the mold I6 thereby compressing the mold I6 sufficiently to withstand the static pressure of casting metal which can then be poured in molten condition into the mold I6 in the usual manner. The pressure of the fluid can be set to approximate or be greater than the static pressure of the metal poured into the mold I6 so that no separation or distortion of the mold parts can occur.

Upon termination of the pouring operation and cooling of the casting metal, the valve 44 is operated to exhaust the pressure fluid in the cham-- bers 24. The steel shot can then be expeditiously removed by application of suction to the pipe 36 which will carry the shot to a common sump (not shown). The arrangement of the outlet 34 within the pipe 36, as previously described, makes it possible for the suction fluid to reach high velocity even when the casing I I! is filled with the refractory material, since the pipe 36 itself cannot become completely filled or blocked.

It will be apparent that casting apparatus for use in pouring molds having an irregular exterior surface has been provided and that the de-" sirable features of shell-type molds are preserved durlng the casting operation. It will furtherbe apparent that many changes may be made in the details of construction and arrangement of parts and in the steps of the method without" departing from the scope of the invention as defined in the appended claims.

I claim:

1. Casting apparatus for a shell-type mold. comprising a casing having an area adapted to contain the mold, said casing having a depth defined by opposite sid walls adapted to be spaced from the mold, a pair of flexible liners extending across said opposite walls andforming therewith a pair of closed chambers within said casing, granular material contained between said spaced mold and opposite side walls, and means for admitting fluid under pressure to said chambers to distend said liners relative to said opposite walls, said liners being thereby cooperable with said granular material and adapted to compress the mold sufliciently to withstand the static pressure of casting material during the casting operation.

2. Casting apparatus as defined in claim 1 wherein said casing is generally rectangular having an open end, said liners being of generally rectangular form secured at the marginal edges to the adjacent side Walls, said side walls having apertures therein with which said means for admitting fluid communicate.

3. Casting apparatus for a shell-type mold, comprising a casing having an area adapted to contain the mold, said casing having a depth defined by opposite side walls adapted to be spaced from the mold, a pair of flexible liners extending across said opposite walls and forming there with a pair of closed chambers Within the casing, granular material contained between said spaced mold and opposite side walls, closure means for one end of said casing having an outlet therein for said granular material, means for admitting fluid under pressure to said chambers to distend said liners relative to said opposite sid walls, said liners being thereby cooperable with said granular material and adapted to compress the mold sufficiently to withstand the static pressure of casting material during the casting operation, and means operable for withdrawing said granular material from said outlet upon termination of said casting operation.

4. Casting apparatus as defined in claim 3 wherein said withdrawing means comprises a suction pipe communicating with said aperture.

5. Casting apparatus as claimed in claim 4 wherein said closure means are connected to said pip with said outlet substantially coincident with the axis of said pipe to prevent blocking thereof by said material.

6. Casting apparatus for a shell-type mold, comprising a generally rectangular casing having an open end and a length and width adapted to contain the mold inserted through said open end, said casing having a depth defined by opposite side walls adapted to be spaced from the mold, a pair of flexible liners of generally rectangular form secured at the marginal edges to the adjacent side walls and forming therewith a pair of closed chambers within said casing, granular material contained between said spaced mold and opposite side walls, said material being refractory and pourable through said open end, closure means for the opposite end of said casing having an elongated outlet therein for said granular material, means for admitting fluid under pressure to said chambers to distend said liner away from said opposite sid walls, said liners being thereby cooperable with said granular material and adapted to compress the mold sufficiently to withstand the static pressure of casting material during the casting operation, and a suction pipe extending substantially parallel with said closure means and having an elongated recess for receiving said outlet substantially coincident with the axis of said pip to prevent blocking thereof by said material.

7. Casting apparatus for shell-type molds, comprising a generally rectangular casing having an open end and a centrally disposed partition, said casing having a length and width adapted to contain a mold on each side of the partition inserted through said open end, said casing having a depth defined by opposite side walls of said casing and partition adapted to be spaced from the molds, a pair of flexible liners of generally rectangular form secured at the marginal edges to the adjacent side walls of said casing and partition respectively and forming therewith a pair of chambers on each side of said partition within said casing, granular material contained between said spaced molds and opposite side walls, said material being refractory and pourable through said open end, a funnel-shaped closure means for the opposite end of said casing having an elongated outlet therein for said granular material, means for admitting fluid under pressure to said chambers to distend said liners away from said opposite side walls, said liners being thereby cooperable with said granular material and adapted to compress the molds sufficiently to withstand the static pressure of casting material during the casting operation, and a suction pipe extending substantially parallel with said closure means and having an elongated recess for receiving said outlet substantially coincident with the axis of said pipe to prevent blocking thereof by said material.

8. A method of casting with shell-type molds comprising inserting a mold substantially midway between spaced oppositely disposed flexible surfaces, positioning granular refractory material in said spaces between the mold and said surfaces, and applying fluid under pressure to said surfaces to distend the same and compress the granular material toward said mold for supporting said mold during the casting operation under substantially uniform pressure at least equal to the static pressure of the casting material.

9. The method as claimed in claim 8 wherein said granular material is poured in said spaces between the mold and said flexible surfaces to completely fill the same.

10. The method as claimed in claim 9 wherein said fluid pressure is released following said casting operation and thereafter said granular material is withdrawn by suction from said spaces.

RALPH P. DAVIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 353,832 Tasker Dec. 7, 1886 1,653,232 Smith Dec. 20, 1927 2,088,123 Toman July 27, 1937 2,192,133 Hagemeyer Feb. 27, 1940 2,383,224 Sorensen Aug. 21, 1945 OTHER REFERENCES Page 506, Metal Industry, December 19, 1947.