GB2162102A

GB2162102A - Improvements in metal pouring devices

Info

Publication number: GB2162102A
Application number: GB08418847A
Authority: GB
Inventors: Harry Wilkinson
Original assignee: FARMER ROPER Ltd
Current assignee: FARMER ROPER Ltd
Priority date: 1984-07-24
Filing date: 1984-07-24
Publication date: 1986-01-29
Also published as: GB8418847D0

Abstract

A coreless type induction heating coil (44) surrounds a lower portion (42) of a refractory lined heating chamber (20). The latter is sealingly closed by a cover (46) so that the surface level (52) of the molten metal in a reservoir (36) of a tapping spout (24) can be held constant by applying air pressure to the heating chamber (20). Fresh charge is introduced from time to time into a filling and emptying spout (22) to maintain the surface level of the molten metal in the chamber (20) at all times above the junctures (33,35) of the oblique channels (32,34) with the chamber (20). Because of the absence of a channel inductor, it is practical to empty the pouring device during short shutdown periods with less risk of the refractory lining cracking and cleaning is easier. <IMAGE>

Description

SPECIFICATION Improvements in metal pouring devices The present invention relates to metal pouring devices and more particularly to pressurized pouring devices of the so-called teapot configuration.

A typical metal pouring device of the above kind is described in U.S.A. Patent No. 3,844,453. The pouring device comprises a refractory lined vessel defining a holding chamber and having at one side a filling passage and on its other side a tapping spout but the vessel has a cover by which the holding chamber can be sealed and means are provided for controllably pressurizing the holding chamber to produce and/or maintain a desired metal level in the tapping spout during pouring. In the case of bottom pouring the tapping spout is provided with a stopper rod and the pressure in the holding chamber is controlled in order to maintain the metal level in the tapping spout constant.

The holding chamber may be replenished from time to time by supplying further molten metal through the filling passage.

The temperature in the holding chamber is maintained at a desired value by means of a so-called channel inductor which is arranged below the bottom of the holding chamber. A channel inductor comprises an induction coil which encircles an arcuate passage whose ends are connected to the holding chamber so that the arcuate passage is kept full of molten metal at all times. The induction coil induces eddy currents in the molten metal to heat the molten metal which in turn is thereby circulated through the channel. The A.C. current through the induction coil can be adjusted to maintain the desired metal temperature in the holding chamber.

Metal pouring devices of the above kind are disadvantageous in that they are difficult to start up and shut down. It must be ensured that metal in the channel of the channel inductor remains liquid at all times. Therefore on start up it is essential to preheat the channel inductor to an extent necessary to ensure that metal when it first flows into the holding chamber does not solidify in the channel. Repeated shutdowns are not desirable because the refractory lining is inclined to crack under the influence of the frequent temperature variations, particularly the refractory lining of the channel inductor. Therefore, the practice is to maintain the metal pouring device at its operating temperature over extended periods, in particular, it is usual to maintain the pouring device at its operating temperature during weekends when it is not being used for metal pouring.This is extremely wasteful of power.

A further disadvantage of the known metal pouring devices is that they are not suitable for pouring spheroidal graphite cast iron. The magnesium in SG cast iron is liable to attack the refractory lining which leads to a buildup of solid material on the lining. Such a buildup gradually restricts the channel of the channel inductor thereby rendering the latter ineffective.

It is an objection of the present invention to provide a pressurized metal pouring device of a teapot configuration.which lends itself to frequent emptying and refilling.

It is another object of the present invention to provide a metal pouring device which can economical for pouring SG cast iron.

According to the present invention, a metal pouring device comprises a refractory lined vessel defining a generally cylindrical holding chamber and having on one side thereof a filling and emptying spout and on another side thereof a tapping spout, the vessel having a cover by which the holding chamber can be sealed and being provided with means for controllably pressurizing the holding chamber to achieve a desired metal level in the tapping spout during pouring, the vessel being furthermore provided with a coreless- type induction heating coil which encircles the lower portion for the holding chamber.

In a preferred construction, the heating coil encircles a portion of the holding chamber which extends below the junctures of the spouts with the holding chamber.

Preferably, the horizontal diameter of the heating coil is greater than its vertical axial dimension.

Since the metal pouring device of the present invention essentially comprises a cylindrical vessel, it can be emptied and refilled frequently without the refractory lining cracking. It is merely necessary to preheat the liner prior to refilling sufficiently to relieve the refractory lining of the thermal shock which it would suffer when it is first contacted by the molten metal. There is no channel type inductor which would make it uneconomic to empty and refill the pouring device frequently.

Since the pouring device comprises essentially a simple cylindrical vessel, a modicum of buildup and deposit on the refractory lining when using the device for pouring SG cast iron does not adversely affect operation of the device. Furthermore, due to the simple cylindrical configuration any buildup can be relatively easily removed during the infrequent shut- down periods. In the case of a channel inductor, removal of the deposit within the channel is difficult or virtually impossible.

The metal pouring device of the present invention will usually be designed for bottom pouring, that is to say the tapping spout is provided with a stopper rod and the metal level in the tapping spout and therefore also in the filling and emptying spout is maintained at a constant level whilst tapping is taking place. For emptying the vessel at the end of a production run the vessel is tilted to pour the whole of the contents out through the filing and emptying spout..

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates a metal pouring device in accordance with the invention for filling a series of moulds advanced stepwise along a production line; and Figure 2 is a vertical cross section of the refractory lined vessel of the pouring device.

The pouring device shown in the drawings comprises a refractory lined vessel 10 arranged so that its axis is normally vertical. The vessel 10 is mounted on a carriage 12 by means of opposed trunnions 14 by which the vessel is pivoted to posts 16 on the carriage. The vessel 10 normally rests in the position shown in Fig. 1 but may be pivoted about the trunnions 14 by operating a pair of jacks 18 which act between the carriage 12 and the vessel 10. To effect complete emptying the vessel may be tilted slightly beyond the horizontal position.

As shown in Fig. 2 the vessel 10 comprises a cylindrical refractory lined holding chamber 20 having on one side a filling and emptying spout 22 and on its opposite side a tapping spout 24.

The refractory lining 26 is supported by means of a metal shell 28 and defines the cylindrical holding chamber 20 and the spouts 22 and 24.

The filling and emptying spout 22 comprises a filling bowl 30 which is connected by an oblique channel 32 to the holding chamber 20. An oblique channel 34 of the pouring spout connects the holding chamber to a reservoir 36 which has a bottom pouring nozzle 38 opened and closed by means of a vertical stopper rod 40.

The junctures 33 and 35 of the channels 32 and 34 with the holding chamber 20 are situated approximately midway along the vertical extent of this -chamber, being slightly below the midpoint of the chamber in the illustrated embodiment. The holding chamber 20 thereby has an extended lower portion 42.

The extended lower portion 42 of the holding chamber 20 is encircled by a coreless induction coil 44 whose horizontal diameter is substantially greater than its vertical axial length. The induction coil comprises a tubular conductor which enables it to be water cooled. The induction coil 44 is surrounded by a flux shield 46 and the whole arrangement is supported by the lower portion of the shell 28 by means not illustrated. The coreless inductor thereby induces eddy currents in the whole of the molten metal in the lower portion 42 of the holding chamber 20. A temperature sensor (not shown) may be provided for sensing the metal temperature in the holding chamber and for adjusting the A.C. heating current in the induction coil 44 to maintain the metal temperature at a desired value.

The holding chamber 20 is sealingly closed by means of a cover 46. A conventional compressed air or inert gas system (not shown) is provided for introducing compressed air through the cover 46 and for releasing such compressed air to maintain a desired pressure within the holding chamber 20 and to adjust this pressure where appropriate in the conventional manner.

For initial filling of the metal pouring device of the invention it is sufficient to preheat the lining 26 to avoid it suffering thermal shock when it is contacted by the metal. Metal can be poured into the holding chamber 20 continuously or intermittently.

In Fig. 1 the filling bowl 30 of the filling and emptying spout 22 is shown being filled from a ladle 50. Instead a conventional launder may be used for introducing molten metal into the filling bowl. The maximum level to which the pouring device may be filled is the level 52 which it is desired to maintain in the pouring spout and reservoir throughout pouring. The metal capacity to achieve this level may typically be 2.25 tonnes. As will be apparent the junctures 33 and 35 of the channels 32 and 34 with the holding chamber 20 must at all times be covered by the molten metal to enable pouring to be achieved and the minimum metal capacity represented by the level 54 may typically be 1 tonne.

That is to say the capacity of the lower portion 42 of the holding chamber is 1 tonne.

As will shortly be described with reference to Fig. 1 intermittent pouring can be achieved by controllably raising and lowering the stopper rod 40.

The pressure within the holding chamber 20 is controlled to maintain the metal level 52 in the reservoir 36, and incidentally also in the filling bowl 30, at the desired level for metal pouring. Similarly, during replenishment of the metal supply in the holding chamber, the pressure therein is controlled during refilling through the spout 22 to maintain the desired level 52.

To empty the device at the end of a production run the pressure in the holding chamber is released and the whole vessel is tilted in the clockwise direction (Fig. 2) about the axis 15 of the trunnions 14, this axis being indicated in its approximate position in Fig. 2. The residual contents of the device are thereby poured out of the device through the spout 22 into a suitable receptacle such as a ladle (not shown). By tilting the vessel slightly beyond the horizontal it may be emptied completely. Because of the substantially circular configuration of the vessel and the complete absence of any complicated channel inductor the refractory lining is not particularly liable to crack. It thereby becomes feasible to empty the device not only at weekends but also overnight thereby offering a substantial power saving.

When using the device to pour SG cast iron access right to the bottom of the holding chamber can be obtained to enable the consequential deposit to be removed from time to time. There are no channels of complicated shape from which it would be difficult or impossible to remove deposit.

Fig. 1 of the drawings shows the metal pouring device of the invention being used to fill moulds in a production line and at the same time being replenished from the ladle 50. The moulds 60 are made automatically on an automatic machine, such as that manufactured by DlSA-Dansk Industri Syndikat A/S. The moulds are made of compacted sand and do not require firing. Thus, they can pass directly from the mould-making machine directly to a mould conveyor 62. The moulds are transported along the mould conveyor 62 in a stepwise fashion by means of a hydraulic ram. The mould conveyor is simply in the form of a channel and the friction of the moulds sliding along such channel is sufficient to hold the moulds tightly in abutment with one another even during filling. The moulds define pouring bushes 64 through which the mould cavities are to be filled.Because of manufacturing vari ations, the positions of the bushes 64 tend to vary somewhat. It is for this reason that the vessel 10 is mounted on the carriage 12.

The carriage 12 is provided with wheels (not shown) which run on rails 66 on an intermediate trolley 68. The latter has wheels 70 which run on longitudinal rails 72. The trolley 12 is provided with a reversible motor 74 for displacing the carriage 12 along the rails 66 and another motor (not shown) is provided for traversing the trolley 68 along the rails 72. These motors are controlled by a computer which actually controls the whole of the operation of the pouring device rendering the device completely automatic except in relation to its initial filling, its replenishment and final emptying.

The pouring spout 24 has a pouring mechanism 76 thereon which incorporates a hydraulic cylinder for raising and lowering the stopper rod 40, this hydraulic cylinder being controlled by the computer. A metal level sensor 78 is also mounted on the tapping spout 24 and is provided with a float for detecting the level of the metal surface. The float can be coupled to the slider of a potentiometer (not shown) whose tap is connected to the computer, the tap of such potentiometer providing an actual measure of the metal level.

The pouring bush detector 80 is also mounted on the tapping spout 24 and is so positioned as to detect the pouring bush before the latter reaches its position for filling the respective mould cavity.

The detector 80 may comprise an electronic eye or electronic camera and is capable of noting the exact position of such pouring bush in relation to the tapping nozzle 38. The detector 80 detects a pouring bush at an exact multiple of the stroke of the mould conveyor ram in advance of the pouring station. If the detector 80 senses that the pouring bush is laterally displaced with reference to the present position of the tapping nozzle 38, this information and the amount of displacement is stored in the computer so that the pouring vessel 10 is adjusted laterally, i.e. by moving the carriage 12 along the rails 66 once that pouring bush has been advanced by four strokes of the conveyor ram being effected.Similarly, if the detector 80 notes that the pouring bush is longitudinally displaced from its desired position relative to the tapping nozzle 38, such information and the actual displacement are stored in the computer and at the appropriate moment the vessel 10 is adjusted longitudinally by displacing the trolly 68 along the rails 22.

To effect each pouring operation the stopper rod 40 is lifted according to a programme which has been stored within the computer memory by means of a "teaching mode" performed on the computer by a skilled foundry operator.

The computer controls the pressure within the holding chamber to maintain the metal at the desired level during replenishment and during tapping. Should there be a pause in the casting process, the metal level can be temporarily lowered so that the metal flows out of the reservoir 36 and the bowl 30.

The conveyor 62 is sufficiently long to enable the moulded articles in the moulds to cool or be cooled until they are solidified. Thereafter, the cast products can be broken out of the moulds.

Claims

1. A metal pouring device comprising a refractory lined vessel defining a generally cylindrical holding chamber and having on one side thereof a filling and emptying spout and on another side thereof a tapping spout, the vessel having a cover by which the holding chamber can be sealed and being provided with means for controllably pressurizing the holding chamber to achieve a desired metal level in the tapping spout during pouring, the vessel being furthermore provided with a coreless-type induction heating coil which encircles the lower portion of the holding chamber.

2. A pouring device as claimed in claim 1, in which the heating coil encircles a portion of the holding chamber which extends below the junctures of the spouts with the holding chamber.

3. A pouring device as claimed in claim 1 or 2, in which the horizontal diameter of the heating coil is greater than its vertical axial dimension.

4. A pouring device as claimed in claim 1, 2 or 3, in which the junctures of the spouts with the holding chamber are situated approximately midway along the vertical extent of this chamber.

5. A pouring device as claimed in any preceding claim, in which the coreless inductor is surrounded by a flux shield.

6. A metal pouring device as claimed in any preceding claim, which is designed for bottom pouring, in that the tapping spout is provided with a stopper rod and the metal level in the tapping spout and therefore also in the filling and emptying spout is maintained at a constant level whilst tapping is taking place.

7. A pouring device as claimed in claim 6, in which the tapping spout comprises a reservoir and an oblique channel connecting the holding chamber to the reservoir.

8. A pouring device as claimed in any preceding claim, in which the filling and emptying spout comprises a filling bowl and an oblique channel connecting the filling bowl to the holding chamber.

9. A pouring device as claimed in any preceding claim, in which said vessel is tiltably mounted on a carriage which runs on a trolley to enable the position of the tapping spout to be adjusted in accordance with the position of a pouring bush of a mould to be filled from the pouring device.

10. A pouring device as claimed in claim 9, which is provided with a pouring bush detector and with a computer for controlling the position of the pouring device in accordance with the detected position of the pouring bush.

11. A pouring device as claimed in any preceding claim, which is associated with a production line comprising a mould conveyor for the stepwise transport of moulds to be filled.

12. A pouring device as claimed in claims 10 and 11, in which the pouring bush detector is located to detect the pouring bush of a mould in ad vance of a mould being filled and the computer is adapted to store the detected position of the pouring bush until the respective mould has reached the position at which it is to be filled.

13. A metal pouring device constructed and adapted to be operated substantially as herein de scribed with reference to and as illustrated in the accompanying drawings.