US3800986A

US3800986A - Apparatus for discharging molten metals with pump emptying means

Info

Publication number: US3800986A
Application number: US00290748A
Authority: US
Inventors: T Stamp
Original assignee: Individual
Current assignee: TBS Engineering Ltd
Priority date: 1971-09-24
Filing date: 1972-09-20
Publication date: 1974-04-02
Anticipated expiration: 1991-04-02
Also published as: DE2245768B2; AT328633B; DE2245768C3; ATA811772A; GB1377628A; DE2245768A1; IT975062B

Abstract

Apparatus for discharging molten metal, such as lead, has a pump demountable from a support member attached to a melting pot, the pump, support member and a ducted block, also mounted on the support member, having cooperating upwardly inclined passages for the flow of the molten metal and terminating in a discharge opening or nozzle. The ducted block and nozzle (where present) are provided with auxiliary heating.

Description

United States Patent [1 1 Stamp [4 1 Apr. 2, 1974 APPARATUS FOR DISCHARGING MOLTEN METALS WITH PUMP EMPTYING MEANS [76] Inventor: Thomas Blackledge Stamp, Silvretta,

Langley Rd., Winchcombe, Gloucestershire, England [22] Filed: Sept. 20, 1972 [2]] Appl. No.: 290,748

[30] Foreign Application Priority Data Sept. 24, 1971 Great Britain 44543/71 [52] U.S. Cl. 222/146 I-IE [51] Int. Cl B22d 37/00 [58] Field 0t Search 222/385, 146 HE, DIG. 10, 222/DIG. 1; 164/316, 318; 417/434, 446

[56] References Cited UNITED STATES PATENTS 2,520,348 8/1950 Tama 222/DIG. 1O l,238,l08 8/1917 Cole 222/DIG. 10

3,396,873 8/1968 Nef 222/DIG. l 3,652,073 3/l972 Lewis 266/38 FOREIGN PATENTS OR APPLICATIONS l,l5l,357 7/1963 Germany 222/385 900,842 7/1945 France l64/3l8 Primary ExaminerRobert B. Reeves Assistant ExaminerDavid A. Scherbel Attorney, Agent, or Firm-Young and Thompson [5 7] ABSTRACT Apparatus for discharging molten metal, such as lead, has a pump demountable from a support member attached to amelting pot, the pump, support member and a ducted block, also mounted on the support member, having cooperating upwardly inclined passages for the flow of the molten metal and terminating in a discharge opening or nozzle. The ducted block and nozzle (where present) are provided with auxiliary heating.

14 Claims, 4 Drawing Figures 7 PATENTEDAPR 21974 3800 986 SHEET 2 BF 2 33 33 FIG. 2.

APPARATUS FOR DISCHARGING MOLTEN METALS WITH PUMP EMPTYING MEANS This invention relates to lead pouring or metering systems as used in lead casting machines and is particularly, though not exclusively, applicable to a lead pouring system for use in a casting machine for casting plates or parts of lead accumulators, comprising a single fixed mould, or a series of moulds mounted on an endless conveyor to be brought in sequence below a pouring outlet of the system. In such machines it is important the quantity of molten metal delivered to each mould shall be fairly accurately controlled and many attempts have been made to design pouring systems which will operate continuously without frequent maintenance.

One such system includes a continuously operating pump supplying molten lead from a melting pot through a long delivery pipe, which is externally heated electrically or by gas, to a pouring ladle from which a continuous overflow or return passage leads back to the melting pot. At appropriate times the ladle is tilted to discharge a metered quantity into a mould. This system has many disadvantages: the molten surface is exposed to air over a large area and is very subject to oxidisation; the velocity of discharge is quite high and uncontrolled and spillage may occur; the metal is ,continuously being supplied to and returned from the ladle so that large heating equipment is necessary to prevent the temperature dropping excessively; and, in the event of any breakdown of the equipment, the whole system has to be shut down and, in some cases, it may even be necessary for the molten metal drained off from the container before the pump can be removed for maintenance.

Accordingly it is an object of the present invention to provide an improved metal pouring system which will be less susceptible to these existing problems and disadvantages.

Broadly stated, the invention consists in apparatus for pouring or metering the discharge ofa molten metal such as lead, comprising a melting pot or container provided with heatingmeans to maintain the metal in a molten state, a pump mounted at least partly within the container with its inlet near the bottom of the container, the pump being physically mounted on a support member connected to or forming part of the container, a discharge passage from the support member and a pump passage in the pump cooperating to provide a path for the discharge of molten metal from the pump to a discharge nozzle or opening so that the pump can be readily demounted from the support member for maintenance or replacement.

Preferably the pump is a reciprocating piston or plunger pump actuated by a fluid operated ram or cylinder, and having non-return valves in its inlet and outlet ports, with means for holding at least one of the valves open, to drain the pump when it is removed from the container, suchas a stop at the end of the valve stem which is spring biassed to hold the valve closed.

It is preferred also that the discharge passage includes a discharge duct formed in a rigid ducted block connected to the other side of the support member referred to above and terminating at the said discharge nozzle or opening. In any case the ducted block and nozzle, if fitted, preferably include auxiliary heater means arranged to increase the temperature of the molten metal. Ideally, in this case, the discharge duct will be a relatively massive metal casting which can act as a thermal reservoir.

In a particular preferred construction according to the invention the discharge passage is inclined upwards to the discharge nozzle or opening to assist in the removal of any air trapped in the passage. Ideally the discharge passage will terminate in a pouring lip or weir at the discharge nozzle or opening to assist in removing any air trapped in the passage, the arrangement being such that at the end of a pouring operation molten metal is retained in and substantially fills the discharge passages.

The invention may be performed in various ways and one specific embodiment with certain possible modifications will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic vertical crosssection illustrating the main components of the pouring system,

FIG. 2 is a vertical cross-section view on the line IIII in FIG. 1,

FIG. 3 is a horizontal cross-section through the pouring head on the line [IIII] of FIG. I, and

FIG. 4 is an enlarged fragmentary side view of the mounting arrangement for the pump shown in FIG. 1.

Referring first to FIG. 1, the apparatus comprises basically a generally rectangular metal melting pot or container 10 provided with internal electrical heating coils 49. This container 10 is mounted at an elevated position on an automatic casting machine, so as to discharge molten lead into moulds moved in sequence by an endless conveyor below a pouring no'zzle. Secured to one side wall 11 of the container, by welding, is an accurately positioned mounting block 12, the block having two, generally vertical, opposed faces, which are inclined from the vertical at a small angle of about 2.

Directly mounted on this support block 12 is a pump unit 13 comprising a main metal body or casting having at its lower end apump cylinder or bore 14 containing a reciprocating piston 15 attached to a pneumatic actuating ram 19 mounted above the pump body. The bottom end of the pump casting is closed by a plate 16 with cooperating inlet and outlet passages 21,22 respectively, fitted with non-return poppet-type inlet and

exhaust valves

23,24 respectively, each attached to sliding stems 50 which extend upwards through drillings in the block and have manually controlled knobs 51 at their upper ends, and are surrounded by springs 52 which tend to hold both valves closed. By depressing the knobs both the valves can be opened. The pneumatic ram 19 contains adjustable limit stops 19A for determining the stroke of the pump and thus the volume of metal supplied. This may also be achieved by an adjustable link 15A in the valve stem.

Since the valves are positioned at the bottom of the pump body, this ensures that they can be maintained in a continually submerged state so that they do not become subjected to oxidation. It should also be noted that removal of the plate 16 enables direct access to the pump chamber, both

valves

23,24 andthe inlet and outlet passages 21,22, so that they can easily be inspected and maintained.

livery nozzle unit 26. The unit 25 comprises a massive generally cylindrical metal casting 28 with a central passage 29. The whole length of this casting is surrounded by electric heaters 27 shrouded in an insulating cover 30. At the near end the casting 28 has a reduced neck 31 and a flange 32 provided with throughdrilling 33 to'receive bolts 37 by which it is secured to the supporting block 12 and the pump unit 13 (see FIGS. 2 and 4). These bolts 37 are positioned well above the liquid metal level so as not to be attacked by the liquid metal and so as to be readily accessible. At the other end the casting has a recess 34 from which drillings extend to the adjacent end face to receive further mounting bolts for securing the pouring nozzle unit 26'. The abutting surfaces of the pump unit 13, the support block 12, the discharge unit 25 and the nozzle unit are ground flat so that there will be no seepage and good physical contact between all these parts and a good contact area, relative to the size of the passage 29, thus providing good heat transfer properties.

The pouring nozzle 26 comprises a casting 35 having a central inlet 36 on its rear face to communicate with thecentral passage 29 in the casting 28, this port 36 opening into a horizontal gallery 38 from which lead two main horizontal outlet slots 40 (see FIG. 3). The surface of theinclined front face 42 of the member 35 is relieved above eachslot 40 as shown at 43, and to this inclined front face 42 is secured a cover plate 44 having a number of inclined delivery slots 45 which lie generally vertical when this plate is secured to the member 45. When the plate 44 is secured in position it provides a lip or weir 47. above the level of the top surface of the gallery 38. It will also be noted that the whole discharge assembly including the two units 25 and26 is mounted on the support block 12 so that the centre line of the flow passage is inclined upwards towards the discharge openings at a small angle of about 2.This assists in movement ofany air along the passage with the molten metal. The combination of the lip 47 with the terminal vertical discharge slots 45 prevents the molten metal issuing with excessive velocity, and so reduces spillage. Also the small area of molten liquid at the lip 47 between pourings is relatively small so that little oxidation occurs. Electric heater units 39 are provided within bores in the nozzle 26 and the nozzle is insulated by a jacket 41.

In use the pneumatic ram 19 is controlled automatically in relation to the stepping movements of the conveyor, and the ram and pump unit 13 are so designed and controlled that an accurate metered volume of molten metal is delivered at each stroke to fill the particular moulds in use. The temperature of the metal in the melting pot may be about 300 -350 C, which is sufficient tomaintain the metal in a fluid state for pumping out below the required pouring temperature ofabout 500 C. By keeping the temperature below this final figure oxidisation in the pot is reduced. The

auxiliary heaters

27 and 41 in the units 25 and 26 progressively raise the temperature of the metal to about 500 C at the pouring lip. Thus, only the metal at the outlet of the nozzle unit 26 will have reached the pouring temperature. The use of a massive metal casting 28 acts as a thermal reservoir so that the temperature of the metal can be raised rapidly during its passage through the relatively short central drilling 29.

The container 10 is provided with an air tight lid 53 so that an inert gas (such as nitrogen) may be introduced into the container 10 through gas inlet 54. This provides a means of reducing or eliminating oxidation of the molten metal. Further metal for melting can be introduced through the hatch 55. The lid 53 fits around the pump unit 13 and can easily be removed to provide access to the pump unit for replacement or maintenance.

If and when the pump 13 requires maintenance, as is to be expected under the conditions experienced, it is relatively simple to dismount and if necessary replace the pump without shutting down the system or draining the melting pot. The mounting bolts 37 holding the pump body to the support block 12 are freed, and the whole pump unit is simply lifted out of the pot, the valves being opened by pressing down the knobs on the valve stems to allow all the molten metal to drain off. No further parts have to be removed and a fresh pump can be substituted very rapidly. In carrying out maintenance on the pump itself, the working parts are readily accessible by removing the plate 16. Likewise if problems arise in the discharge unit 25 or the delivery nozzle 26 one or both parts can readily be removed and replaced without closing down thesystem.

Various modifications may be made to the design and construction of the apparatus shown in the drawings, within the scope of the invention, as claimed herein. Thus, the melting pot 10 can be shaped other than rectangular, such as circular. Also, the mounting block 12 can be secured to the melting pot by means other than welding, such as by bolting the block to the wall 11. Furthermore, the angle subtended to the horizontal by the flow passage, can be other than 2, as desired.

I claim:

1. Apparatus for discharging of a molten metal such as lead, comprising a melting pot, heating means associated with the melting pot to maintain the metal in a molten state, a pump mounted at least partly within the melting pot, the pump having an inlet near the bottom of the melting pot, and valve means to allow flow only in a discharge direction, a support member, integral with the melting pot providing a physical mounting for the pump, a discharge passage defined to lead from the support member, a pump passage defined in the pump, cooperating with the discharge passage to provide a path for the discharge of molten metal from the pump, a discharge opening being provided at the outlet of said path, and mounting means for releasably mounting the pump on the support member together with means for holding the valve means open to enable the pump to be drained when it is removed from the melting pot, being provided, so that the pump can be readily demounted from the support member and drained for maintenance or replacement.

2. Apparatus according to claim 1, in which the pump is a reciprocating piston pump actuated by a fluid operated ram, and having inlet and outlet ports, the valve means comprising non-return valves provided for the inlet and outlet ports.

3. Apparatus according to.claim 2, in which the valve has a valve stem and the means for holding the valve means open comprises a stop at the end of the valve stem and spring biassing means for holding the valve closed.

4. Apparatus according to claim 2 wherein the pump is a positive displacement pump having variable characteristics whereby a metered, but variable, quantity of molten metal may be delivered on each stroke of the piston.

5. Apparatus according to claim 1, including a rigid block, having a discharge duct, wherein the discharge passage includes the discharge duct, mounting means corrects the rigid block to the side of the said support member opposite to the pump, and the discharge duct terminates at the said discharge opening.

6. Apparatus according to claim 5 wherein the abutting surfaces of the pump, support member and rigid block are ground flat to avoid seepage, and provide a good contact area and heat transfer properties.

7. Apparatus according to claim 6, in which auxiliary heater means are arranged in association with the ducted block to increase the temperature of the molten metal.

8. Apparatus according to claim 5, in which the ducted block is a relatively massive metal casting which can act as a thermal reservoir.

9. Apparatus according to claim 5, in which the discharge passage is inclined upwards to the discharge opening to assist in removing any air trapped in the passage.

10. Apparatus according to claim 1, in which a pouring lip is formed at the termination of the discharge passage, so arranged that, at the end of a pouring operation, molten metal is retained in and substantially fills the discharge passage.

11. Apparatus according to claim 1, in which the discharge opening is in the form of at least two slots.

12. Apparatus according to claim 1, in which an inclined front face is formed on that part of the apparatus where the discharge passage terminates, and the discharge opening is formed on that inclined front face.

13. Apparatus according to claim 12, in which a cover plate having a number of inclined delivery slots is provided over the discharge opening, so that the slots will lie generally vertical when the cover plate is secured to the said inclined front face.

14. Apparatus according to claim 1, in which a discharge nozzle is provided at said discharge opening.

Claims

3. Apparatus according to claim 2, in which the valve has a valve stem and the means for holding the valve means open comprises a stop at the end of the valve stem and spring biassing means for holding the valve closed.

10. Apparatus according to claim 1, in which a pouring lip is formed at the termination of tHe discharge passage, so arranged that, at the end of a pouring operation, molten metal is retained in and substantially fills the dis-charge passage.