Foundry machines for filling molds with sand

May 16, 1961 f. hansberg 2,983,971

FOUNDRY MACHINES FOR FILLING MOLDS WITH SAND

Filed June 28, 1955 3 Sheets-Sheet 1

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May 16, 1961 f. hansberg 2,983,971

FOUNDRY MACHINES FOR FILLING MOLDS WITH SAND

Filed June 28, 1955 3 _Sheets-Sheet 2

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Fr/tz Hansberg

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May 16, 1961 f. hansberg 2,983,971

FOUNDRY MACHINES FOR FILLING MOLDS WITH SAND

Filed June 28, 1955 3 Sheets-Sheet 3

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INVENTOR

Fritz Hansberg

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2,983,971

Patented May 16, 1961

United States Patent Office ¹

2,983,971

FOUNDRY MACHINES FOR FILLING MOLDS WITH SAND

Fritz Hansberg, Via Borgonuova 10, Modena, Italy

Filed June 28,1955, Ser. No. 518,583

Claims priority, application Germany July 19, 1954

Claims. (CI. 22—36)

This invention relates to improvements in foundry machines for filling molds with sand. The invention more particularly relates to improvements in foundry machines for filling molds with sand utilizing a compressed gas such as compressed air.

Various types of foundry machines are known which utilize a compressed gas such as air for filling core or casting molds with core or casting sand. These machines may be divided into two fundamental categories, i.e., the blowing machines and the shooting or ram-shot machines.

The blowing machines utilize the compressed gas to entrain the sand and convey the sand-in-gas suspension thus formed into the mold. The shooting machine utilized the pressure of a sudden burst of compressed air for forcing the sand in a closed charge into the mold.

In contrast to the blowing machines in which a thorough mixing of the air and sand must be effected to form a true sand-in-air suspension, in the shooting machines, the gas is only used to force the sand as a compact mass into the mold without mixing with the gas. In, for example, the shooting machine as described in German Patent No. 524,373, compressed air acts in the manner of an elastic piston on one end of a compact sand column and forces it rapidly into the mold through a nozzle. As the compressed air rapidly enters from the one side and acts on the end of the sand column, the other side of the sand column is passed through the nozzle in the form of a compact jet and fills the mold partially or completely depending upon the quantity of sand. Due to the high acceleration imparted the sand column emerging from the nozzle by the pressure of the compressed air, the sand completely fills all the cavities iii the mold in the form of a dense, coherent body. Since air does not enter into the mold together with the sand, special precautions need not be taken for the escape of the air from the mold as is necessary in connection with blowing machines operated with substantial quantities of air in accordance with the mixed air-sand principle or blowing principle.

In both the blowing and shooting machines, a rand Chamber is provided having a compressed gas inlet valve at one end portion and ah outlet nozzle for the sand at the Other end portion. A perforated plate is preferably positioned about the nozzle and the mold is pressed up in contact with the plate. In order to effect the filling operation with a supply of sand in the sand chamber, the inlet valve is opened admitting the compressed air and forcing the sand out of the said chamber through the nozzle into the mold until the mold is filled and the sand contacts the perforated plate and the nozzle. In the case of shooting machines, a limited quantity of compressed air is allowed to suddenly expand into the sand chamber filled with sand by the sudden opening of the inlet valve which may be designated the “shooting” valve as a result of which the sand shoots out of the nozzle as a compact mass into the core mold and fills it until positive closure by contact of the sand with the nozzle and perforated plate.

After the filling of the mold, the sand chamber is still under compressed gas pressure. In the case of a blowing machine, the pressure is the full pressure of the blowing air, while in the case of the shooting machine, the pressure is the residual pressure of the quantity of expanded compressed air.

After the filling of the mold, the mold must be removed from the nozzle and perforated plate as, for example, by lowering in the case of a vertically extending sand chamber. If the mold is merely removed, the remaining pressure in the sand chamber will force additional sand through the nozzle. It is therefore necessary to allow the excess pressure to escape from the sand chamber as, for example, by venting before removing the mold.

Prior to the instant invention, the venting of the sand chamber was effected with a special vent valve positioned on the side or front of the sand chamber. The vent valve had to be closed prior to the charging of the sand chamber with compressed gas and had to be opened after the filling of the mold and prior to the removal of the sand.

The opening and closing actuation of the vent valve was conventionally pneumatically effected by actuation of the main control Valve which opened and closed the gas inlet valve or shooting valve leading into the sand chamber. When the vent valve is in the form of a diaphragm valve, the same is conventionally controlled by releasing the pressure on one control side of the diaphragm through the main control valve, allowing venting Of the sand chamber.

These known vent valves had various disadvantages with respect to their manufacture and operation.

In manufacturing the device, it was necessary to provide a separate valve housing and suitable compressed air-feed for the venting and to provide the main control valve with special control channels. In operation, after each filling process, the venting had to be commenced by a suitable operation of the main control valve, which in the case of larger sand chambers, involved a delay.

One object of this invention is an improved venting construction which overcomes the above disadvantages; which is considerably simplified both in manufacture and structure; which will operate at a much higher speed than the conventional venting devices and which will allow venting of the sand chamber to be automatically effected at the end of the filling process and which will not require special control lines and the like. This and still further objects will become apparent from the following description read in conjunction with the drawing in which:

Fig. 1 is a side elevation partially in section of the head of an embodiment of a shooting machine having a horizontal valve construction provided with an embodiment of a vent constructon in accordance with the invention.

Fig. 2 is a vertical section showing the vent valve of Fig. 1 On a larger scale,

Fig. 3 is a side elevation partially in section showing the head of a shooting machine with a vertical valve construction embodiment of the vent, in accordance with the invention.

While the invention will be described in detail with reference to a shooting machine, the same is applicable to any foundry machine for filling molds with sand which have a sand chamber with a compressed gas inlet valve as, for example, the conventional blowing machines.

In accordance with the invention, a gas outlet vent from the sand chamber is defined through the compressed gas inlet valve and preferably through a hollow

2,983,971 open ended valve rod for actuation of the valve. Means are provided for sealing the outlet vent when the compressed gas inlet valve is in the open position allowing the admission of compressed air into the sand chamber and for opening the vent when the inlet valve is in the closed position. The hollow open ended valve rod through which the vent is defined, is preferably axially movable for the opening and closing actuation of the inlet valve. A sealing member is preferably positioned with respect to the end of the valve rod opposed to the valve so that when the valve rod is axially moved to the position opening the valve, the end of the valve rod is in sealing contact with the sealing member and when the valve rod is axially moved to the position of closing the valve, the end of the valve rod is in space relationship to the sealing member allowing gas to escape from the sand chamber through the valve rod. The valve rod is preferably connected to the piston of a fluid actuated control valve in the housing of which the sealing member is positioned.

Referring to the embodiments as shown in the drawing, the heads of the shooting machine as shown in Figs. 1 and 3, are of conventional construction and operation except for the novel venting arrangement in accordance with the invention. In the machine head shown in Fig. 1, the compressed gas inlet valve into the sand chamber, i.e., the shooting valve, is horizontally positioned and the machine is provided with an upper sand charging slide. In the embodiment shown in Fig. 3, the compressed gas inlet valve is vertically positioned and a swingable sand supply chamber is provided. Excepting for the novel venting construction, in accordance with the invention, the construction and operation of the device is substantially identical to that described, for example, in U.S. Patent No. 2,611,938 of September 30, 1952.

In the drawings, 3 designates the sand chamber, 10 the chamber or conduit for the compressed air and 2 the compressed gas inlet valve or shooting valve. In accordance with the invention, the valve rod 1 for actuating the inlet valve 2 is hollow and open ended so that any residual compressed gas remaining in the sand supply chamber 3 after shooting of the sand into the core mold may escape therethrough in order to vent the sand chamber 3. The compressed gas inlet valve 2 and the valve rod 1 are axially movable. When moved to the position shown in the drawing, the valve 2 is in the closed position preventing the entry of compressed air from the compressed air chamber 10 into the sand chamber 3. When the rod 1 and valve 2 are axially moved in the direction away from the sand chamber 3, the compressed air may rapidly pass from compressed air chamber 10 into the sand chamber 3, ramming or shooting the sand through the nozzle at the lower end of the sand chamber into a core mold which may be held in position below the sand chamber.

In order to effect the axial movement of the valve rod 1 and thus the opening and closing actuation of the valve 2, the end portion of the valve rod 1 opposed to the valve 2, is connected to a control piston 4 of a control valve. The valve rod 1 is screwed into a threaded bore extending into the central portion of the control piston 4. An extension of the threaded bore extends through the entire control piston 4 so that the fluid passing through the hollow valve rod 1 can pass through the control piston. The construction of the control piston may best be seen from Fig. 2.

The control piston 4 is axially movable within a cylinder formed by the housing 15. The control piston 4 is resiliently biased by means of the spring 7 pressing the valve rod 1 and valve 2 in a closed position. A compressed gas may be forced into the control space 6 of the control valve through the inlet 5, thus forcing the piston to move against the force of the spring 7 and moving the valve rod 1 and valve 2 to the open position. When the pressure is relieved from the space 6 through the connection 5, the spring 7 automatically returns the piston 4 and presses the valve rod 1 and the valve 2 to the closed position. A resilient sealing ring 9 of rubber or the like is positioned opposite the central bore through the control piston 4 so that when the control piston 4 is moved against the force of the spring 7 by the introduction of compressed air into the space 6, the surface of the control piston 4 developed as the valve disc 8 will be pressed against the sealing ring 9 sealing the end of the hollow valve rod 1 Since the hollow bore through the control piston 4 forms an extension of the bore through the valve rod 1, the piston with this bore may be considered as a part or an extension of the valve rod 1 so that the sealing contact between the valve disc 8 of the piston 4, and the sealing member in the form of the sealing ring 9 will be referred to herein and in the claims as a sealing contact between the end of the valve rod and the sealing member.

When the valve surface 8 of the control piston 4 is spaced from the sealing ring 9 by movement of the control piston 4 caused by the spring 7, gas may escape from the sand chamber through the valve 2 and valve rod 1, the vent valve 11 and outlet connection 12 in the direction of the arrows shown to the atmosphere thus relieving any excess pressure in the sand chamber 3.

In order to protect the slide surface of the control piston 4 from entrained sand, a protective cylindrical sleeve 13 is connected with the control piston 4 on the side facing the valve 11. The protective sleeve 13 moves in sliding engagement with the packing seal 14, thus preventing the entrance of sand between the control piston 4 and the cylinder formed by the housing 15. The valve rod 1 passes through the housing 15 in sliding engagement with pressure tight seals or packings.

The housing 15 is made in two detachable portions so that the individual parts of the control valve assembly are readily accessible for maintenance.

In operation, in the embodiment shown as Fig. 1, sand from the sand charging slide 16 is passed into the sand chamber 3 by means of the slide valve 18 controlled by means of the piston and cylinder arrangement 17 and connecting rod 19. With the sand in the sand chamber 3, slide valve 18 is closed.

In the embodiment as shown in Fig. 3, the sand chamber 3 charged with sand is rotated by means of the bearing arrangement 21 around the pipe 22 into the position shown in sealing contact with the upper portion of the head by means of the gasket arrangement 23.

In both embodiments, the core mold to be filled with sand is pressed against the perforated plate 20 at the bottom of the sand chamber. The core mold to be filled may be held in this position, for example, by means of a pneumatic piston arrangement or the like.

The connection 5 is freely vented so that the spring 7 may press the control piston 4, the valve rod 1 and the valve 2, to the sealed position.

Compressed air pressure is built up in the air chamber 10 but cannot enter the sand chamber since the valve 2 is closed. In order to effect the filling of the core mold, compressed air is passed in through the inlet connection 5 into the space 6 forcing the control piston 4 against the spring 7 toward the vent valve 11. As the control piston 4 is moved in this direction, the valve disc 8 formed on the piston 4 presses against the sealing member in the form of the sealing ring 9, sealing the end of the hollow control rod 1. The movement of the piston with the valve rod also opens the valve 2 allowing the charged air in the air chamber 19 to suddenly rush in to the sand chamber 3 forcing sand as a compact charge through the nozzle into the core mold until the same is filled with the sand pressing against the perforated plate 10.

After the filling of the core mold, the pressure is released from the space 6 through the connection 5. The spring 10 quickly forces the control piston 4 in a direction away from the vent valve 11 closing the valve 2.

When control piston 4 is moved in this direction, the

2.983.971 valve disc 8 is moved away from the sealing ring 9 so that any residual pressure in the sand chamber 3 may pass out through the hollow interior of the valve rod, control valve 4 and valve vent 11 and outlet connection 12 to the outside. With the residual pressure in the sand chamber thus automatically relieved, the filled core mold may be removed as, for example, by lowering and the operation repeated.

While the invention has been described with reference to the specific embodiments shown, various changes and modifications will become apparent to the skilled artisan which fall within the spirit of the invention and scope of the appended claims,