US3445041A - Liquid dispensing assembly with improved filling means - Google Patents

Description

20, 1969 J. 5. CAMPBELL ET-AL 3,445,041

LIQUID DISPENSING ASSEMBLY WITH IMPROVED FILLING MEANS Filed Oct. 5. 1966 IN VEN T035 JAMES SAMUEL CAMPBELL W/LFRED ERNEST WILLIS BY WARREN, BROSLER, GYPHER 8 AN 6L M! A T TOR/V575 United States Patent 3,445,041 LIQUID DISPENSING ASSEMBLY WITH IMPROVED FILLING MEANS James Samuel Campbell, Orinda, and Wilfred Ernest Willis, San Francisco, Calif.; said Campbell assignor to Campbell Auto-Pour Engineering, Berkeley, Calif., a corporation of California Filed Oct. 5, 1966, Ser. No. 584,547 Int. Cl. B6741 /02, 5/54 U.S. Cl. 222-152 2 Claims ABSTRACT OF THE DISCLOSURE Dispensing of molten metal from a furnace by applying inert gas pressure to said furnace to force the metal out of a tube, and further applying said gas to the tube.

Our invention relates to apparatus for the dispensing of liquid and more particularly to the filling of such apparatus with liquid to be dispensed, with special application of the invention in the dispensing of molten metal from a furnace or receptacle in the casting of molds, and will be described in its preferred form with respect to such application.

For some die-casting and permanent rnold applications and some other applications, it becomes desirable to recharge, or refill, the furnace or equivalent receptacle without interrupting the pattern of dispensing operations. For example, in die-casting or permanent mold casting, the dies or molds are kept heated to the correct operating temperature range by the liquid metal which is poured into them. Once the proper time interval between pouring has been determined, this pouring pattern should be maintained during operation. If this pattern is interrupted or delayed, the die or mold may cool to below its proper operating temperature range. Then, the next casting or castings will probably be defective until the die or mold again reaches its proper operating temperature.

Such interruption or delay in the pouring pattern may, in a conventional setup, be due to the necessity of occasionally recharging or refilling the furnace. And if the furnace be pressurized, replenishing of the same with prevailing type of equipment, must of necessity cause an interruption in the dispensing of contents therefrom.

Among the objects of our invention are:

(1) To provide novel and improved apparatus for the dispensing of liquid, having improved filling means which will not necessitate an interruption or alteration of a prevailing pouring pattern,

(2) To provide novel and improved liquid dispensing apparatus of the pressurized type, having means permitting filling thereof without interrupting or altering dispensing operations,

(3) To provide novel and improved pressurized furnace assembly or equivalent, for dispensing of molten metal protected by inert gas, such novel and improved pressurized furnace assembly incorporating means for recharging a furnace in a very simple and convenient manner with molten metal, while minimizing contamination of the metal entering the furnace,

(4) To provide novel and improved means for enabling filling of a pressurized liquid dispenser through a stand pipe arrangement.

Additional objects of our invention will be brought out in the following description of a preferred embodiment of the same as applied to the dispensing of molten metal, taken in conjunction with the accompanying drawing, wherein, the figure is a schematic diagram of a pressurized furnace assembly utilizing inert gas as the pressuring medium, and incorporating the improved filling means of the present invention.

Referring to the drawing for details of our invention in its preferred form as applied to the dispensing of molten metal, the same comprises a furnace 1 having a cover 3 adapted to be sealed in place, and a pour passageway in the form of a pouring tube 5 extending from a low point within the furnace, below the normal liquid level range therein, to a high point at its discharge end 7, above the maximum contemplated liquid level within the furnace. At its discharge end, it preferably connects with a downwardly directed nozzle or equivalent 9, in a structure forming a small chamber 11 above the junction with the nozzle.

The specific furnace illustrated is one of the pressurized type providing a gas chamber 12 above the molten metal therein. Pressuring gas is introduced into the furnace through a tube 13, entering preferably through the cover of the furnace and terminating at a point below the normal liquid level range in the furnace, whereby gas entering through the tube will exit from the lower end thereof and percolate up through the molten metal into the gas chamber to develop pressure therein. This form of gas intake is employed where the gas is of an inert type, such as nitrogen or argon, which is capable of degassing the metal as it percolates up therethrough.

Gas pressure in the chamber is preferably built up to a value sufficient to raise a column of molten metal in the pouring tube, to an elevation 14, approaching the high or discharge point thereof, where it will be ready to pour upon development of a slight increase in pressure. Such increase in pressure should be suflicient to raise the molten metal to an elevation 15 within the small chamber 11, above the junction of the pouring tube and nozzle, to assure a full constant flow of molten metal at the higher or pour pressure.

It is characteristic of this furnace, as disclosed in the application of Wilfred Ernest Willis for Pressure Pour Apparatus, Ser. No. 524,955, filed on Nov. 30, 1965, issued on Oct. 17, 1967 as US. Patent No. 3,347,427 that the externally applied pressures will not require changing, despite changes in gas pressure within the furnace with change in liquid level therein. This characteristic enables an operator to control operations of the furnace with two discrete pressures, namely, a ready-to-pour" pressure sufficient to maintain the level in the pouring tube at the ready-to-pour level 14, and a pour pressure of just slightly higher value, sufficient to raise the level to the pour level 15 within the chamber 11, as previously mentioned.

A gas flow line 17 from the gas chamber 12 in the furnace, to the chamber 11, is provided, to protect the metal in the pouring tube against oxidation and other sources of contamination, the flow through this connection being controlled by a valve 19, adjusted to limit flow to a value of the order of a leak.

The ready-to-pour and pour pressures may be applied to the furnace through the degas tube 13 exclusively, as described in the aforementioned Willis application, but for a quicker build up of pressure within the furnace, some of the gas may be fed directly into the gas chamber of the furnace at appropriate time in the operation of the furnace, in accordance with the teachings of the application of Robert B. Rice, Jr. for Gas Feed to Pressure Pour Apparatus, Ser. No. 564,953, of July 13, 1966, US. Patent No. 3,395,833, issued Aug. 6, 1968.

In accordance with this latter method of feeding gas to the furnace, dry inert gas from a pressure tank 23 is reduced through a pressure regulator 25 to a value capable of being readily handled by the system of the present invention. Such value will necessarily be somewhat above the pour pressure value. The gas is supplied to a manifold 27, from which a connection 29 feeds a pair of branch lines 31, 33, one of which connects to the degas tube 13, and includes a pressure regulator 35 adjusted to the ready-to-pour pressure value, and made responsive to the pressure in such line.

The other branch line 33 leads directly to the gas chamber in the furnace, preferably by coupling into the leak flow line 17, and includes a pressure regulator 41 adjusted to the pour pressure value, and made responsive to the prevailing pressure in the first branch line 31, downstream of the ready-to-pour pressure regulator 35.

A normally closed solenoid operated valve 43 in the line 29 connecting to the branch lines, may be energized to open position, to condition the furnace for operation, while a normally closed solenoid operated valve 45 in the pour pressure branch line 33, may be energized to its open position, to initiate a pouring operation following establishment of the 'ready-to-pour pressure in the degas tube. Such opening of the pour pressure line will supply gas at this pressure directly into the gas chamber of the furnace until the build up of pressure in the furnace, reacting through the degas tube, causes the pour pressure regulator to shut off.

Thus, dispensing of molten metal through the pouring tube will commence upon opening of valve 45, and as the pressure within the furnace tends to drop with such discharge of metal, the pour regulator 41 will open and bring the pressure back up to a value which will cause the reactive pressure through the degas tube to again close off the pour regulator, and such cycling of the pour regulator will continue with discharging of metal from the furnace.

Upon completion of a pour operation, restoration of ready-to-pour pressure may be accomplished by momentarily opening the leak line 17 to atmosphere or an accumulator (not shown), through a normally closed solenoid controlled valve 47.

A second line 49 from the manifold to the degas tube, includes a throttling valve 51 adapted to limit flow to a leak value slightly below the leak flow from the gas chamber. This leak flow line to the degas tube includes a normally open solenoid controlled valve 53 which remains open during pouring and during non-pressurized condition. It is closed during ready-to-pour conditions.

In the operation of a furnace assembly without the present invention, filling is accomplished through the opening of a door 57 in the cover or roof of the furnace, and inas much as this procedure exposes the gas chamber to atmosphere, pressure conditions change, and consequently, all pouring operations have to cease while the furnace is being recharged.

In accordance with the present invention this is no longer necessary, for we provide a filling tube preferably in the form of a stand pipe 57, extending from a point in the furnace or receptacle, below normal liquid level range, to a high point above the pour passageway or pouring tube 5, such stand pipe preferably extending through the cover of the furnace, in which it is sealed.

When so installed, the molten metal will rise in the stand pipe to the same level to which it rises in the pouring tube, and due to the column of liquid thus formed in the filling tube, no gas may escape from the furnace through this tube.

As it becomes necessary to recharge or replenish a furnace so provided with a filling tube, all one need do, is pour such metal into the tube. Due to the fact that the column of liquid in the filling tube cannot rise above that prevailing in the pouring tube, metal will exit from the bottom of the tube to raise the level in the furnace.

Should recharging be undertaken during a ready-topour condition, the tendency for the infiowing metal to slightly raise the prevailing gas pressure in the furnace, could conceivably cause a slow but temporary discharge 4 from the pouring tube. This could be alleviated by operating the furnace at a lower ready-to-pour level.

In the alternative, the leak flow could be increased to compensate. This may be realized by shuntting the leak valve 19 by a line 59 including a leak valve 61, adjusted for greater flow, and a normally closed solenoid controlled valve 63 which may be under operator control. During refilling, the operator could temporarily increase the leak flow and thus preclude such build up of pressure. A pressure gauge 65 connected into the leak fiow line 17 will enable an operator to readily accomplish such pressure control.

To facilitate the adding of molten metal to the furnace in this manner, a funnel 67, may be added to the filling tube, and it in turn may be fitted with a cover 69, either hinged or sliding, preferably the latter, whereby to seal off the column of molten metal therein from continuous exposure to the atmosphere.

Where the pressure gas is of the inert type, to blanket the molten metal in the furnace as well as the pouring tube with a protective covering of gas, we provide means for similarly protecting the molten metal in the filling tube.

We have accomplished this by installing in the sliding cover, a hose connection fitting 71, which by means of a flexible hose coupling 73, is connected to a flow line from the manifold, said flow line including a manually adjustable throttle valve 77 which is closed sufficiently to provide a leak flow through the line to maintain a blanket of such gas over the metal. Also included in such line is a solenoid controlled valve 79 of the normally closed type.

Coupled to the same flexible hose connection, is a gas feed line 81 extending from the leak flow line 17, and in this connection, is a normally closed solenoid controlled valve 83, which when opened, will permit flow of gas to the filling tube from the gas chamber 12 in the furnace, via the leak flow line 17.

The solenoid controlled valve 79 in the How line to the filling tube from the manifold, is energized to be held open during ready-to-pour condition of the furnace, and is deenergized to its normally closed condition during a dispensing operation.

While a dispensing operation is in progress, gas feed to the filling tube is preferably switched over to the leak fiow line, by deenergizing solenoid valve 79 and simultaneously energizing the solenoid controlled valve 83, and this, in turn, is made responsive to a slight build up in pressure in the chamber 11 above the nozzle, occuring at the start of a pouring cycle as the molten metal rises into such chamber. A pressure switch 84, coupled into the leak flow line adjacent this chamber, is set to respond to such slight rise in pressure to adjust the solenoid controlled valves in question, along the lines disclosed in the aforementioned Willis application.

In lieu of switching from line 75 to line 81 during pour, the line 75 may be permanently maintained in flow connection with the filling tube, while the line 81 may be flow coupled to a mold during pour as depicted in the Willis application, in which case, the solenoid valve 79 may be removed.

The filling tube embodied in the present invention as described, provides a very simple and convenient way of recharging a furnace or equivalent receptacle with molten metal to be dispensed, and such filling operation may be undertaken at any time, without adversely interfering with the dispensing of metal from the furnace, particularly where the dispensing of the contents of the furnace may be by gas pressure, for the liquid column supported in the filling tube, functions as a pressure seal to block escape of such gas.

A melt-down furnace which might conceivably be employed in supplying refill metal to the furnace, could conceivably be more suitable for rapid melting, and metal supplied from such furnace for refilling the present furnace, probably would not be thoroughly degassed and cleansed by the time it is introduced into the filling tube. After entering the furnace, however, such added metal becomes exposed to the degassing provided by the inert gas entering the degas tube, and thus can be thoroughly purified while awaiting dispensing.

In lieu of employing a separate or independent filling tube as illustrated as described, the filling tube may be coupled into the pouring tube, which would efiect some economy, and might be preferred, where the metal supplied to the furnace meets quality requirements, for some of that metal, during dispensing, might mix with the metal being dispensed, without entering the furnace interior, and therefore should be of a quality satisfying the prevailing requirements for purity.

The term normal level range as employed herein, represents the difference between the level to which the furnace would normally be filled and the level at which recharging of the furnace would normally be undertaken. Neithter level is deemed critical.

From the foregoing description of our invention, it will be appreciated that the same fulfills all the objects attributed thereto, and while we have illustrated and described the same in considerable detail, it will be apparent that the same is subject to alteration and modification without departing from the underlying principles involved, and we accordingly do not desire to be limited in our protection to the specific details so illustrated and described, except as may be necessitated by the appended claims.

We claim:

1. A furnace assembly comprising a receptacle for liquid and having a pour passageway extending from a low point therein below normal liquid level range, to a high point above such normal liquid level range,

a filling tube extending from a point in said receptacle below normal liquid level range to a high point above the high point of said pour passageway,

means providing a gas chamber in said receptacle above said liquid,

means for conducting gas under pressure to said chamber,

means for controlling the gas pressure in said chamber,

said last named means including means connectible to a source of inert gas under pressure, for selectively feeding said inert gas to said receptacle at either a low pressure sufficient to elevate liquid in said pour passageway to a ready-to-pour elevation, or a higher pressure sufficient to elevate liquid in said pour passageway to a pour elevation to initiate a pour cycle, and

means for conducting some of said inert gas to said filling tube.

2. A furnace assembly as recited in claim 1, characterized by means conducting some of said gas to the high point of said pour passageway during a ready-to-pour condition, and means for switching said gas from said pour passageway high point to said filling tube during a pour period.

References Cited UNITED STATES PATENTS 12/ 1965 Shearman 222394 X l/l966 Holz et al 222397 X US. Cl. X.R.

Images