GB2059029A

GB2059029A - Charge bucket for an induction furnace

Info

Publication number: GB2059029A
Application number: GB7932126A
Authority: GB
Original assignee: BBC BROWN BOVERI BRITISH
Current assignee: BBC BROWN BOVERI BRITISH
Priority date: 1979-09-17
Filing date: 1979-09-17
Publication date: 1981-04-15
Also published as: GB2059029B

Abstract

The invention relates to a charge bucket for an induction furnace. A charge bucket has a container 10 with a discharge mechanism at its base for allowing a charge in the bucket to be dropped into a furnace. The container 10 is double walled and has an outer wall 12 and an inner liner 14. This enables the inner liner to be replaced and additionally provides between the inner liner 14 and the outer wall 12 an annular space which is connectable by means of ducting 50 directly to an extraction fan system to allow smoke billowing from the furnace during charging to be extracted without entering the foundry environment. <IMAGE>

Description

SPECIFICATION Charge bucket for an induction furnace The present invention relates to a charge bucket for an induction furnace.

A wide variety of systems are employed for conveying the charge material to a furnace.

Such systems extend from simple direct charging into the furnace by means of a magnet crane to fully mechanised systems with a programmed operating cycle which require no intervention by the foundry personnel. Purely manually controlled charging is subject to practical limitations as melting capacities become greater. However, the amount of mechanisation and automation for any given case is largely dependent on cost considerations.

A characteristic feature of operating an induction furnace is that it is charged in separate instalments. Apart from the magnet crane for small installations, therefore, the charge bucket provides the simplest answer. This is a bucket, which in the past has adopted any of several shapes, which is conveyed to the top of the furnace and trap doors at the base of the bucket are opened to discharge the load directly into the furnace. The bucket may be carried to the furnace by any of a variety of conveying systems including cranes, overhead tracks, roller conveyors and fork lift trucks.

As the charge bucket is placed over the top of the furnace and the flaps lowered to allow the charge to fall into the furnace, a large volume of smoke and dirt is displaced and normally billows out from the sides of the bucket and causes environmental problems within the foundry.

It has been known to place directly above the furnace an air extraction system in order to mitigate this problem but this has not proved entirely satisfactory.

In accordance with the present invention, there is provided a charge bucket having a double walled container for containing a charge and a discharge mechanism at the base of the container for permitting the charge to fall into a furnace, the double wall of the container defining an annular channel open at both its lower and its upper end and being connectable at its upper end directly to an extraction mechanism so as to enable exhaust gases from the furnace to be removed by passing between the walls of the charge bucket without entering the ambient environment.

Conveniently, the double walled structure of the container may be achieved by providing a single walled container with an inner removable liner. The removability of the liner offers the advantage that it can be replaced readily, the liner being the part of the bucket which is subjected to considerable abuse as the charge is dropped into it.

The invention will now be described further, by way of example, with reference to the Bccompanying drawings, in which: Figure 1 is a view from above of a charge bucket in accordance with the invention, and Figure 2 is a section along line A-B in Fig.

1.

A charge bucket has the form of a container generally designated l O which is double walled having an outer wall 1 2 and an inner liner 14. Ribs 1 6 project radially inwards from the outer wall 1 2. The inner liner 14 is provided at its lower end with a collar 1 5 and at its upper with a collar 1 3 which are both in the form of an inverted U so as to form with the inner liner an enclosed channel. Slots are formed in the two collars 1 3 and 1 5 through which the ribs 1 6 pass so that the liner may be axially slid into the outer wall 1 2 but is not rotatable relative to it.Additional ear-pieces 1 7 formed with holes 20 are provided at the top of the liner to enable it to be lifted out of the outer wall of the container 10.

The bottom of the container 10 as viewed in Fig. 2 is closed by means of four flaps 22 each of which is secured to a lever arm 24 pivotable about a pin 26 arranged at the base of the container in a manner generally similar to that of a conventional discharge mecca nism of a charge bucket.

A rectangular lifting frame is provided with lugs 32 for attachment to chains by means of which the lifting frame 30 can be raised and lowered. The lifting frame and the outer wall 1 2 of the container are provided with ribs 34 and 36 which interengage to allow the lifting frame to slide but not to rotate relative to the outer wall 1 2. The lifting frame is connected to each lever 24 by means of a pair of connecting arms 38 and 40 and a plate 42 which is pivotably mounted on flanges secured to the outer surface of the outer wall 1 2 of the container. As the lifting frame 30 is raised, the plate 42 shown in Fig. 2 and the lever 24 rotate anti-clockwise to raise the flap 22 into a position closing the bottom of the container.Continued raising of the lifting frame lifts the whole charge bucket with its base remaining closed so as to retain any charge loaded into the bucket. When the lifting frame 30 is lowered, after the base of the charge bucket rests on the furnace to be charged, continued descent of the lifting frame results in the flaps 22 opening both under the weight of the lifting frame and the weight of the charge within the bucket. The charge then enters the furnace, this always being accompanied by billowing smoke and fumes.

To prevent the smoke from entering the environment of the foundry through the discharge mechanism at the base of the charge bucket, an extraction fan system is directly connected by means of a telescopic duct generally designated 50 to the annular space between the inner lining and the outer wall 1 2 of the charge bucket. The extraction fan can thus remove the smoke and fumes directly at their source without substantial environmental pollution.

In addition to solving a serious pollution problem, it will be seen that the invention offers the advantage of providing a charge bucket with a replaceable liner so that the lifetime of the bucket is prolonged by virtue of the replaceability of the part which is most subjected to wear.

Claims

1. A charge bucket having a double walled container for containing a charge, said double wall defining an annular channel open at both its lower and its upper end and being connectable at its upper end directly to an extraction fan system so as to enable exhaust gases from the furnace to be removed by passing between the walls of the charge bucket without entering the ambient environment.

2. A charge bucket as claimed in Claim 1, in which the double walled structure of the container is achieved by providing a single walled container with an inner removable liner.

3. A charge bucket constructed substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.