US2550642A - Centrifugal casting machine - Google Patents

Description

April 24, 1951 T. E. JOHNSON CENTRIFUGAL CASTING MACHINE Filgd July 22, 1948 2 Sheets-Sheet 1 ILIII INVENTOR.

A ril 24, 1951 1-. E. JOHNSON 2,550,542

' CENTRIFUGAL CASTING momma Filed July 22, 1948 v 2 Sheets-Sheet 2 27' INVENTOR.

Patented Apr. 24, 1951 TENT OFFlCE GENTRIFUGAL CASTING MACHINE Thomas E. Johnson, Freeport, IlL, assignor to The Illium Corporation, a corporation of Delaware Application July 22, 1948, Serial No. 40,115

4 Claims.

This invention relates to centrifugal metal casting machines.

a machine in which the direction of rotation of the spinning member may be conveniently changed and further, the speed of the spinning member is continuously and steplessly variable. Another'object is to provide a smoothl operating brakin system for the centrifuge which may be adjusted to apply any desired braking force.

In the accompanying drawings,

Fig. l is an elevational view, partly in section, of the casting machine in position for pouring, an elevated position being indicated in broken lines;

Fig. 2 is a plan view of the machine; and

Fig. 3 is a schematic representation of the hydraulic system which operates the casting machine.

In the centrifugal casting of metal, as contemplated by this invention, the mold is spun at a high rate of speed as the metal is being poured in order to assure entry of the molten metal into all remote parts of the mold cavity and to assure a sound, dense casting. This spinning of the mold results in the exertion of very great centrifugal forces which represent a hazard to persons or equipment in the vicinity of the machine as injury may be caused by the breaking or loosening of a part of the whirling apparatus. To prevent such injury or damage, centrifugal casting machines have heretofore been provided with circular steel shields intended to confine any material thrown from the spinning apparatus to the area within the shield. As an alternative safety arrangement, the entire casting apparatus is sometimes permanently mounted in a pit so that the mold is well below the floor level. The shielded unit is deficient from the standpoint of safety 1 and both types of equipment are inconvenient to use.

The casting machine herein shown. and described enjoys the greater safety of the pit and,

at the same time, it is convenient to load and unload. This convenience is, of course, manifested in reduced cost of castings.

The optimum speed of rotation of the mold during the pouring operation varies with the dimensions and nature of the casting to be produced. The apparatus herein described offers complete flexibility and control of rotation speed and also provides means for smoothly braking the spin to bring it to a stop as rapidly as possible and thus permit most efficient use of the equipment.

A heavy base plate i which supports the entire apparatus is rigidly mounted in fixed position upon channel beams 2 which, in turn, may be embedded in the concrete Walls 3 of pit 4; A platform 5. conveniently substantially coextensive with base plate I, is arranged above the base plate and supported by the latter against rotation by means of shafts 6 which are rigidly attached to platform 5 and slide vertically in bearings i fitted upon base plate i An hydraulic cylinder 8 is mounted upon the underside of base plate i by means of flange '8. Shaft It] extends from piston I I within hydraulic cylinder 8 through packing gland l2 to flange l3 which is fastened to the underside of platform 5. The hydraulic connections of cylinder 8 are not shown in Fig. 1 of the drawings but are indicated in the schematic representation of Fig. 3.

The casting centrifuge assembly is mounted upon platform 5. Brackets M support hydraulic motor assembly l5 upon the platform. Similarly, spin head It is rotably mounted upon platform 5 by base IT. The details of construction of motor assembly [5 and spin head it are not hown or described since they are well known and form no part of the invention. The former includes an hydraulic motor 1 8 (hydraulic connections not shown), suitable bearings, shaft l9, and outboard sheave 2! The spin head it, which is driven by V-helts 2! includes a supportin post 22,.hub 23, mold table 24, and suitable bearings within the hub structure.

The hydraulic system for operating the spinning and elevator mechanisms of the castin machine is illustrated schematically in Fig. 3. The individual component elements of this system are standard parts which will not, therefore, be described in detail. These elements include a motor 25 and pump 25 coupled thereto, both being shown mounted upon a fluid reservoir 21, relief valves 28 and 29, and three four-port, three-p0"- sition. valves 3E3, SI, and 32, in addition to hyclraulic cylinder 8, fluid motor I8, and necessary connecting fluid lines.

port 48.

Any suitable fluid, such as petroleum oil, may be employed in the operation of the hydraulic apparatus. Pump 26, driven by electric motor 25, forces the fluid to port 33 of valve 38, the fluid passing through relief valve 28. Arrows on the fluid lines indicate the direction of flow. If the fluid pressure exceeds a predetermined maximum value at relief valve 23, this valve automatically operates to shunt the fluid to the return line at 34 through which it flows back to reservoir 21.

In one position of valve 36, fluid flowing into port 33 is directed to port 35 and thence to valve 3| controlling the operation of hydraulic motor l8. In 'a second position of valve 33, the fluid is directed to port 36 from which it flows to valve 32 which controls the elevator mechanism by determining the position of piston II. In a, third position of valve 3|}, the fluid is directed to port 31 and thence to the return line at 38. Each position of control valve 30 establishes connection between inlet port 33 and only one of the three outlet ports of the valve. The other two outlet ports are closed.

In one position of valve 3|, fluid entering the valve at inlet port 39 is directed to port 46 from which it flows to hydraulic motor 58 and causes the same to rotate in a given direction. Fluid so flowing through hydraulic motor l8, having entered the motor at port 4|, leaves the motor at port 42 and returns to valve 3| at port 43. This spent fluid then passes to port 44 and thence to the return line at 45. Thus, two channels through valve 3| are open simultaneously.

The speed of rotation of the spin head is controlled by a throttle or regulator valve 5i in a line connecting the motor supply line at 52 and the return line at 53. regulated by valve is shunted directly to the return line in order to limit the motivating fluid pressure at the motor. Maximum speed is attained when valv 5| is closed. Alternatively, the regulator valve may be connected across the two lines fill-4| "and 4342, in parallel with relief valve 29, or may be otherwise arranged to shunt fluid from a motor supply to a return line.

Hydraulic motor is may be caused to rotate in the reverse direction by shifting valve 3| to a second position. This reverses the flow in the motor circuit, the fluid leaving valve 3| at port 43, entering the motor at port 42 and flowing a from the motor through port 4|, returning to valve 3| at. port 45, "and flowing to the return line at 45 through port 44. The two oppositely directed arrows on the lines between valve 3| and the hydraulic motor indicate that fluid may flow in either direction, depending upon the position of the control valve.

In a third position of valve 3|, the fluid is bypassed from inlet port 39 to outlet port 44 and thence to the return line.

,Fluid directed to elevator control valve 32 by valve 30 may be used. to raise or positively lower piston I within hydraulic cylinder 8. In a first position of valve ti, fluid entering the valve at port 43 is directed to port 47 from which it flows into cylinderB above piston i l, as indicated. At the same time, an equal amount of fluid flows from cylinder 8 below piston H into valve 32 at This fluid is channeled by the valve to port 49 from which it passes to the return line at 38. In a second position of valve 32, the fluid isdii'ected into cylinder 3 below piston H from port 43, a corresponding volume of fluid returning to valve 32 at port 41 and being returned to the return line at 38 through port 49. In a third position of valve 32, ports 41 and 48 are closed and the fluid is by-passed from port 46 to port 49 and thence to the return line at 38.

In the operation of the casting machine so described, platform 5 and the apparatus supported thereby is elevated to a position convenient for mounting the mold upon mold table 24. Approximately floor level is generally convenient for preparing the machine for pouring, but the machine may be designed to elevate the mold table to a greater or lesser extent. A semi-elevated position of the spinning apparatus is indicated in broken lines in Fig. 1.

This elevation of platform 5 is accomplished by proper manipulation of valves 38 and 32 with motor 25 and pump 25 in operation. Piston H and shaft H) are forced upwardly to lift flange l3 and platform 5. When the apparatus has reached the desired level, its position is maintained by A quantity of the fluid,

shifting valve 32 to its third position to close ports 47 and 48.

When the mold has been properly fastened to mold table 24 and is ready for pouring, platform 5 is lowered to a position which will bring the entire mold below the level of the floor. The position of valve 33 i then changed to direct the fluid to the spinning apparatus and valve 3| is set in the proper position to cause hydraulic motor is to spin the mold in the desired direction. The metal is poured into the mold while the latter is rotating at the desired rate.

Following the pouring process, the position of valve 3| is shifted to close ports 40 and 43 and by-pass the fluid to the return line. The inertia of the spinm'ng apparatus will continue to rotate hydraulic motor l8 which then functions as a pump to build up a high pressure in the pump return line. This pressure is transmitted to relief valve 29 which controls its magnitude, and thus the braking effect of the return line pressure, by permitting automatically controlled flow to the return line of the system through outlet port 53.

When the spinning apparatus has been brought to a stop, platform 5 may again be elevated to remove the mold and casting and to prepare the machine for a successive casting operation.

While hydraulic power for operation of the casting machine is preferred because of the flexi'oility and control of operation which this form of power means offers, pneumatic, direct-acting electric motors. or other forms of motivation may be used to operate the elevator and/or spinning apparatus. The apparatus herein described may readily be adapted to these alternative forms of motivation. Other forms of elevator and centrifuge mechanisms may also be used. For example, lift chains or a lift screw may be employed to lift the supporting platform, and a multiplemold arrangement wherein the molds are swung around the axis of rotation may be used in place of the single mold rotated on an axis which passes through it, as described herein.

Invention is claimed as follows:

1. A. centrifugal casting machine comprising means forming a pit, a platform arranged within said pit, a spin head mounted upon said platform, an hydraulic motor mounted upon said platform and operatively connected with said spin head, an hydraulic cylinder assembly vertically arranged within said pit underneath said platform, said cylinder assembly having a shaft arranged in supporting relationship to said platform, a fluid pump for continuously supplying fluid under pressure to said hydraulic motor and said hydraulic cylinder, a motor control valve and a cylinder control valve, a primary control valve adapted to direct fluid from said pump to either said motor control valve or said cylinder control valve, said cylinder control valve being adapted to direct fluid from said primary control valve to either the top or to the bottom of the cylinder of said hydraulic cylinder assembly.

2. A centrifugal casting machine in accordance with claim 1 in which said hydraulic motor is adapted to rotate in either direction and said motor control valve is adapted to direct fluid from said primary control valve to either of two ports of said motor to cause said motor to rotate in either direction.

3. A centrifugal casting machine in accordance with claim 1 and including a manually-operated speed regulating valve connected in shunt between the motor supply line and a return line and adapted to by-pass a regulated quantity of fluid from said supply line to said return line.

4. A centrifugal casting machine in accordance with claim 1 and including a relief valve connect- 6 ed in shunt across the supply and return lines of said motor and adapted to by-pass fluid from the return line to the supply line when the fluid pressure in the return line exceeds a predetermined value.

THOMAS E. JOHNSON.

REFERENCES CITED The following reierences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 412,687 -Wilkinson Oct. 8, 1889 1,227,639 Manly May 29, 1917 1,299,918 DeLavaud Apr. 8, 1919 1,783,094 Moore et a1 Nov. 25, 1930 2,236,467 Clench Mar. 25, 1941 2,279,822 McCarroll et a1 Jan. 20, 1942 FOREIGN PATENTS Number Country Date 658,925 Germany Apr. 19, 1938

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