IMPROVEMENTS IN LIQUID METAL DISTRIBUTION SYSTEMS IN BILLET MOULDS

Abstract: A system for filling billet moulds, especially with liquid aluminium, in which a flume (1) is situated fundamentally horizontally with a downwards spout at one end, with the liquid metal flowing along the said flume (1). The spout deposits the metal on a horizon­ tally arranged V cross section bucket (17), with upward concave arms. The upper arm has an access hole (18) for metal towards the other arm, which finished in a horizon­ tal end near the bottom of the billet mould. The buckets are situated on a rotating bucket (6) elevator and the flume tilts, as does the bucket elevator.

Description: This Patent, relates to a Liquid metal distribution device for billet moulds. The patent refers to the filling of billet moulds in automatic billeting lines, more particularly in the aluminium and alloying industry. In traditional mechanisms, deficiencies have been observed; one of them is derived from the formation of surface scum or dross on ingots or billets which normally needs to be removed and the other of these deficiencies stems from,the breakage of the billet mould when it comes with a billet not removed from the mould. All this usually makes it necessary to construct complex, noisy automated devices, in order to avoid the above-mentioned deficiencies. The aim of the patent is to obtain a device and a operative method for filling billet moulds, by means of which the billets are produced free of scum or dross, and therefore, internally healthy, free of gases, etc. Another object of the patent is to achieve equal filling of all the billet moulds. Another object of the patent is to provice a system or method of operation which is simple and has a long service life, which does not break when faced with normal founddry problems and which is also easy to maintain. At this end, the device includes a liquid metal input which is mainly horizontal and slow by means of a horizontal flume with one free end tilted downwards on the side of the billet mould, a liquid metal output projecting towards a bucket that is housed in the billet mould, near the bottom of it, such that the end of the flume becomes housed in the inside of the bucket having an upwards concave wall that is arranged below the tilted end of the flume, and is provided with a hole and opens the way to another concave shaped wall arranged below the earlier one, forming an outlet near the bottom of the billet mould, with an out put end towards this bottom that is fundamentally horizontal, so that a perfect laminar movement of the liquid metal and stepped pouring into the billet mould are assured, means for tilting the flume to allow ists spout end to enter and/or leave the concave interior of the bucket. To achieve these objectives, the patent gives a laminar movement to the metal to the bottom of the billet moulds. Taking into account that the greatest speed component of the liquid is horizontal, we will try to succeed in carrying out pouring in steps and without obstacles in this horizontal movement, while at the same time the drop in height will be minimized. Taking into account that the liquid metal arrives at the billet moulds along a flume, the patent provides a bucket elevator type device which is preferably geared with the billet moulds, with which the metal does not find any obstacles in its route from the flume and is gently led towards the bottom of the said billet moulds. According to the patent, the bucket elevator is equipped with a series of specially shaped buckets, through which the metal slides towards the bottom of the billet mould, through one of its ends. The bucket elevator, together with the buckets, is situated vertically and the flume along which the liquid metal flows accedes to the buckets on board the bucket elevator, so that each one of the buckets penetrates into the inside of the billet mould and very near its bottom. The buckets are specially shaped, as will be described later. The bucket elevator is mounted on an axis which allows it to rotate, and the other end of this axis is in turn mounted on two bearings that are supported by a tilting structure, which, operated by an item such as a jack, for instance, can be raised and lowered at will. Between the bucket elevator and the bearings, the bucket elevator axis carries a draw pinion, which is geared with the billet mould chain in such a way that movement of the billet moulds causes circular movement of the bucket elevator, through the said pinion. Evidently, the nomber of buckets on the bucket elevator will be arranged and adjusted so that when the assembly is in operation, a bucket from the bucket elevator will be situated over a billet mould and will penetrate into the said billet mould and reaches near its bottom. At this moment, the spout end of the flume penetrates inside the bucket of the bucket elevator and pours the liquid metal on the bucket, which deposits it in the billet mould. Each bucket has a raised portion on the side near the flume, whose spout end goes beyond this raised portion and penetrates into the bucket. Starting from this raised portion the bucket has a concave syrface towards the upper part, where there is a hole cut just near the end of the flume spout, and the liquid metal passes through this hole towards another lower surface of another area of the bucket situated below the previous one. The last area of the bucket is inclined gently upwards and ends in a horizontal outlet towards the billet mould, with which the liquid metal is gently deposited on the bottom of the billet mould. The bucket elevator provides a lower area in each position during its rotation, on which the liquid metal that arrives from the flume is stored, so that when the position of a bucket coincides with that of a billet mould, the liquid metal escapes towards the outlet of the said bucket through the hole. Within this technique, the best results are achieved with bucket elevators that have 18 buckets and 18 holes. A production of 10 tons per hour can pass through a 45 mm. diameter hole with billet mould pitches or steps of between 180 and 250 mm. Usually, the bucket elevators are manufactured of grey-iron casting or cast steel, the reason why they never die because of the attack of liquid aluminium coming from the feeding flume. The bucket elevators are cold and it is necessary to preheat them so that the metal does not solidify in contect with them. To this effect, a wall thickness has been calculated such that if the aluminium is sufficiently heated to circulate through the pouring hole, no heating is needed during casting, but only preheating. To do this, it has been agreed that the most suitable method is a propane gas generator. As was stated earlier, the bucket elevator is equipped with its own raising system, which becomes necessary when, for any cause, the billet mould chain stops, with the billet moulds full of metal and with the bucket of the bucket elevator inserted. In this situation, solidification of this metal would lead to breakage of the cucket and the death of the bucket elevator. Generally, the bucket elevator could, in such an event, be driven or moved by the buckets themselves, and in many cases it is installed in this way. However, when alloys of a greater viscosity are sued, there is the risk that the draw mark will appear on the ingots or billets. For this, a drive pinion is fitted which centres the bucket in the billet mould. The arrival channel for the liquid metal is made up of a bucket elevator casing of grey-iron casting and an arrival casing, also of grey-iron casting. The bucket elevator is made of grey-iron casting or cast steel and has a minimum wall thickness of some 8 mm. All these and other details of the patent will be observed in relation to the sheet of drawings which is adjoined, in which, only as a guide, the following are represented: Figure 1 is a general elevation of the installation that the patent foresees. Figure 2 is the above, seen from the top. Figure 3 is a detail of the arrival of the flume towards one of the buckets of the bucket elevator, in accordance with the patent. Figure 4 is a view of the above, when seen from the right. Figure 5 is an enlarged detail of the arrival of the flume at the bucket of the bucket elevator, and how this bucket becomes inserted near the bottom of the billet mould. In accordance with these figures, we will point out firstly in Fig. 1 the flume (1) for liquid metal access towards the billet moulds (7) in the billet mould chain which have to be filled. The front end (5) of the flume (1) accedes towards the inside of the bucket elevator (6), which is arranged vertically over the billet moulds (7). The bucket elevator is mounted on an axis (8) which is supported on the bearings (10) situated on the tilting structure (11), which can be raised by the mechanism (12) and the jack (13), all of which is operated from the control position (14). On the axis (8) is fitted the draw pinion (9), which is connected, in this case, to the billet mould chain (15), so that the movement of the billet mould chain is adjusted to the turning of the bucket elevator (6), in order that the different buckets correspond during the said turning with the position of a billet mould. In Fig. 2, the top view of the above shows the position of the burners (16) for heating of preheating the bucket elevator (6). As regards Fig. 3, it can be seen how the spout (5) at the end of the flume (1) is directed towards the inside of the bucket elevator in such a way that on arrival of the liquid metal, it is deposited in this interior. At the same time as the bucket elevator (6) turns, the spout (5) coincides with the buckets (17) and, more precisely, with the holes (18) cut in its upper base, just at the moment that the bucket is housed in the inside of the billet mould (7 - Fig. 5) and near the bottom of it. The liquid metal flows towards the lower portion of the bucket and from there and by the surface (20), it goes out through the side opening (19) (Figs. 3, 4 and 5). The liquid metal is thus given a laminar movement to the bottom of the billet mould, with a minimum height drop and without any steps. The lifting mechanism (11)-(12)-(13) allows the bucket elevator (6) to be raised to extract the bucket (17) from the bottom of the billet mould, when, for any reason, the billet mould chain stops. In this case, the end (1) of the bucket is raised from the portion (2) and over the base (3). The bucket elevator (6) is centred inside the billet mould by adjustment of the bearings (10) that support the axis (8). In the same way, the elevation of the bucket elevator is adjusted so that the arrival flume does not leave the bucket elevator field. It is important to emphasize, once that the nature and advantages of this invention patent have been described, that it has a non-restrictive character, in that changes in the shape, material or sizes of its constituent parts will not in any way alter its essence, as long as they do not mean a substantial variation of the whole.

Claims: Liquid metal distribution device for billet moulds, comprising a liquid metal input which is mainly horizontal and slow by means of a horizontal flume (1) with one free end (5) tilted downwards on the side of the billet mould (7), a liquid metal output projecting towards a bucket (17) that is housed in the billet mould, near the bottom of it, such that the end of the flume (1) becomes housed in the inside of the bucket (17) having an upwards concave wall that is arranged below the tilted end of the flume, and is provided with a hole (18) and opens the way to another concave shaped wall arranged below the earlier one, forming an outlet near the bottom of the billet mould (7), with an output end towards this bottom that is fundamentally horizontal, so that a perfect laminar movement of the liquid metal and stepped pouring into the billet mould are assured, means for tilting the flume to allow ists spout end to enter and/or leave the concave interior of the bucket. Device according to claim 1 characterized in that adjacent to the billet mould line, on the opposite side to the flume input, a tilting structure (11) is arranged that culminates at the top in a base on which are mounted bearings (10) which receive an axis (8) mounted on them, in that the outlet of the said axis towards the billet mould receives a draw pinion (9) which is operated by stops on the billet mould chain belt on its movements along the belt, with the said pinion being mounted on a bushing whose free end receives a bucket elevator (6) in whose side surface a series of buckets (17) are made to receive the flume spout, in that each step of the billet mould chain corresponds to an angular turn of the bucket elevator to arrange a bucket over each billet mould and below the metal input spout of the flume, with these latter ones being formed by angular units by way of an inclined V with its crest or vertex on the side of the metal arrival flume, with the two arms being concave upwards, of which the upper one is provided with a hole and the lower one ends in an outlet that is fundamentally horizontal. Device according to claims 1 and 2, characterized in that the buckets are preferably grey-iron castings, with a wall thickness of between 8 and 10 mm., and the hole in its upper arm has a diameter of approximately 45 mm. Device according to claims 1 and 2, characterized in that the tilting flume is made of cast grey-iron. Device according to claim 3, characterized in that the buckets are made of cast steel. Device according to claim 2, characterized in that the billet mould arms are of a length of between 180 and 250 mm. Device according to claim 2, characterized in that a unit is provided to heat the bucket elevator and its buckets by using gas burners, specially for propane gas. Device according to claim 2, characterized in that the bucket elevator is provided with a lifting system, based on the scissor arrangement of the support structure for the bearings and axis.

Inventors: ALFARO, D. IGNACIO
Applicants: REMETAL, S.A.
Application year: 1989
Main classification: B22D11
IPC codes: B22D5, B22D39