METHOD AND APPARATUS FOR SETPWISE ADVANCING MOULDS IN A MOULD-STRING FOUNDRY PLANT

Abstract: The stepwise advancing of moulds (5) in a mould-string foundry plant, comprising a mould-making station (A), a pouring station (B) and a conveyor (C) for stepwise advancing the moulds (5), comprises the steps of: a) producing moulds (5) one at a time in the mould-making station (A) for delivery to the conveyor (C); b) stepwise advancing the produced moulds (5) on the conveyor (C) through th epouring station (B) in closely juxtaposed position, forming a mould-string (F) with casting cavities at mainly vertical parting surfaces between successive moulds (5); d) pouring metal (7) into the casting cavities in the pouring station (B), while the moulding string (F) is kept stationary. By separately producing and discharging a first mould (5) without moving the mould string (F) and producing and discharging a second mould (5), and simultaneous delivery of the first and second moulds (5) to the conveyor (C) and advancing the mould string (F) over a distance corresponding to the length occupied by two moulds (5) from the mould-making station (A), and simultaneously pouring metal (7) into two casting cavities while the mould string (F) is kept stationary, the time for pouring the moulds can be increased, thereby avoiding turbulence in the liquid metal during pouring.

Description: METHOD AND APPARATUS FOR STEPWISE ADVANCING MOULDS IN A MOULD-STRING FOUNDRY PLANT TECHNICAL FIELD The present invention relates to a method and an apparatus for stepwise advancing moulds in a mould-string foundry plant of the kind set forth in the preamble of claims 1 and 4, respectively. BACKGROUND ART In mould-string foundry plants of this kind it is known to produce the moulds one at a time in the mould-making station and deliver the produced moulds to a precision conveyor, advancing the moulds stepwise to a pouring station, in closely juxtaposed position forming a mould string with casting cavities at the mainly vertical parting surfaces between successive moulds. Each step in the stepwise advancement of the mould string corresponds to the length occupied by one mould and the mould cavities are filled with liquid metal one at a time in the pouring station. The advancing of the moulds is partly performed by the mould-making station pushing a produced mould against the mould string, partly by advancing the precision conveyor, on which the mould string is positioned. The time available for the pouring is the standstill period for the stepwise advancement of the mould string, said standstill period being closely related to the production time of the mould-making machine. A foundry plant of this kind is e.g. known from EP-0,817,690. DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a method and an apparatus of the kind referred to above, with which it is possible, when producing moulds at a high rate, to have ample time for gently pouring the moulds in order to avoid turbulence in the liquid metal during the pouring step, and this object is achieved with a method of said kind, which according to the present invention also comprises the features set forth in the characterizing clause of claim 1 and an apparatus for performing the method, which also comprises the features set forth in the characterizing clause of claim 4. With this arrangement, the stepwise advancing of the moulds is performed in steps corresponding to the distance occupied by two moulds and the mould- making machine is allowed to produce two consecutive moulds, i.e. two cycles for the mould-making machine, before the mould string is moved again, thereby substantially increasing the time for pouring relative to the time available when proceeding in the traditional way. Preferred embodiments of the method and apparatus, e.g. comprising insertion of cores in the mould cavities, are revealed in the sub-ordinate claims. BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed part of the present description, the invention will be explained in more detail with reference to the exemplary embodiment of a method and an apparatus for stepwise advancing moulds in a mould-string foundry plant according to the invention shown in the drawings, in which Figure 1 diagrammatically shows a mould-string foundry plant, in which the method in accordance with the present invention can be performed, Figure 2 diagrammatically shows the sequence of operations in the mould-making machine during production in accordance with the present invention, Figure 3 diagrammatically shows the movements of the squeeze plates in the mould-making station, Figure 4 shows a sequence of operations corresponding to Figure 2 for a modified version of the apparatus in Figure 1 , in which cores can be inserted in the mould cavities, Figure 5 shows the movements of the squeeze plates corresponding to Figure 3 for the Figure 4 modification, and Figure 6 shows a sequence of operations corresponding to Figures 2 and 4 for a further modified version of the Figure 4 modification. DESCRIPTION OF THE PREFERRED EMBODIMENTS The mould-string foundry plant shown in Figure 1 comprises a mould-making station A producing moulds one at a time for delivery to a precision conveyor C, advancing the moulds stepwise to a pouring station B, in which metal is poured 7 into the casting cavities formed at the mainly vertical parting surfaces between successive moulds. After pouring in the pouring station B, the mould string F is advanced stepwise to the extraction station E, in which the produced castings are taken out of the moulds. The mould-string foundry plant can further comprise a core-insertion station D for inserting cores into the mould cavities before closing thereof. The pouring station B is provided with two pouring units 7 in order to be able to pour metal into two mould cavities simultaneously. The sequence of operations in the mould-string foundry plant shown in Figure 1 is shown diagrammatically in Figure 2. In this Figure, the mould-making machine is shown to the right diagrammatically comprising a mould-forming chamber 4 closed to the right by a squeeze plate 1 and to the left by a swingable squeeze plate 2 and comprising means 3 for introducing mould sand into the mould-forming chamber 4. The sequence of operations in Figure 2 is related to the movements of the squeeze plates 1 , 2, said movements being illustrated in Figure 3 indicating the speed of the squeeze plates as a function of time. The different operations of the mould-making machine are numbered op. 1-6. Taking Figure 2 from the top, the mould string F is stationary during op. 1 - op. 4a and metal can be poured into the mould cavities in the pouring station B. During operation op. 1 , the mould-forming cavity 4 is filled with mould sand from the sand hopper 3. During the operation op. 2, the sand in the mould-forming cavity 4 is compacted by moving the squeeze plate 1 and the swingable squeeze plate 2 towards one another. During the operation op. 3, the swingable squeeze plate 2 is moved to the left and swung out of the way, thereby opening the mould-forming cavity 4 ready for delivery of the produced mould, which is performed during operation op. 4a, during which the produced mould is moved by moving squeeze plate 1 , thereby moving the produced mould to close proximity of the previously produced mould and performing a mould close-up at a low speed. During operation op. 4b, the produced mould is moved onwards together with the mould string F over a distance corresponding to the length occupied by one mould 5 in the mould string F. Before starting this movement, it will naturally be necessary to stop the pouring in the pouring station B. During operation op. 5, the squeeze plate 1 is returned to its starting position and during operation op. 6, the mould-forming chamber is closed by moving the swingable squeeze plate 2 to its starting position. During this operation op. 6, the mould string F is moved one step further, over a distance corresponding to the length occupied by one mould in the mould string, whereafter pouring can be initiated in the pouring station B for the next two mould cavities to be poured. After this, the operations op. 1 - op. 3 are performed as described above. Operation op. 4 is performed by moving the squeeze plate 1 at a relatively high speed until the produced mould 5 comes to the mould close-up position illustrated. The mould close-up is performed without moving the mould string F, due to the fact that room has been provided for the produced mould by the movement of the mould string F during operation op. 6, as described above. Thereafter, the operations op. 5 and op. 6 are performed and the sequence is continued from operation op. 1 as described initially. These operations are illustrated in Figure 2 down to operation op. 4a, where the pouring in the pouring station B is stopped. As can be seen from Figure 2, the time available for pouring metal into the mould cavities in the pouring station B is extended compared to the traditional method, in which the mould string F is moved one step forward during each delivery of a newly produced mould in operation op. 4b. Furthermore, as illustrated in Figure 3, the cycle time for the operations op. 1 , op. 2, op. 3, op. 4, op. 5, and op. 6 is reduced compared to the traditional operations op. 1 , op. 2, op. 3, op. 4a, op. 4b, op. 5, and op. 6. If cores are to be inserted in the mould cavities before closing the moulds, this is done during operation op. 2, as illustrated in Figure 4. Apart from the core insertion by means of the core-setter 8, Figure 4 corresponds essentially to Figure 2. However, the time necessary for inserting the core may necessitate a certain delay between operations op. 2 and op. 3, as illustrated in Figure 5. If an ordinary core-setter with a certain movement pattern is to be used in connection with this machinery, the second step of the movement of the mould string, which in Figure 2 was performed during operation op. 6, will have to be delayed in order to insert the core in the last produced mould before moving the mould string, whereby the second step of the movement of the mould string will have to be delayed until operation op. 3. This will reduce the relative time available for pouring, as illustrated in Figure 4. If, however, the core-setter 8 is constructed to have a possibility of inserting cores in two different positions, the movements of the mould string can be performed as illustrated in Figure 6, which essentially corresponds to Figure 4 apart from the fact that the mould string F is moved the second step forward during operation op. 6, whereby the pouring in the pouring station B can be initiated immediately thereafter, and the core is inserted into the last produced mould during operation op. 2, as illustrated in Figure 6, thereby increasing the time available for pouring metal into the mould cavities. Although the method above has been described with reference to a diagrammatically illustrated apparatus, in which the filling of the casting cavities is performed from the top, it is evident that the same method can be used in connection with filling from the bottom or the side of the mould string, which is preferred in connection with casting of light-metal alloys.

Claims: CLAIMS 1. Method for the stepwise advancing of moulds (5) in a mould-string foundry plant, said plant comprising a mould-making station (A), a pouring station (B) and a conveyor (C) for stepwise advancing the moulds (5), said method comprising the steps of: a) producing moulds (5) one at a time in the mould-making station (A) for delivery to the conveyor (C), b) stepwise advancing the produced moulds (5) on the conveyor (C) through the pouring station (B) in closely juxtaposed position, forming a mould-string (F) with casting cavities at mainly vertical parting surfaces between successive moulds (5), c) pouring metal (7) into the casting cavities in the pouring station (B), while the mould string (F) is kept stationary, c h a r a c t e r i z e d by step a) further comprising separately producing and discharging a first mould (5) without moving the mould string (F) and producing and discharging a second mould (5), and simultaneous delivery of the first and second moulds (5) to the conveyor (C) step b) further comprising advancing the mould string (F) over a distance corresponding to the length occupied by two moulds (5) in the mould string (F), when the first and second mould (5) are delivered to the conveyor (C), and keeping the mould string (F) stationary until delivery of the next two moulds (5) from the mould-making station (A), and step c) further comprising simultaneously pouring metal (7) into two casting cavities while the mould string (F) is kept stationary. 2. Method in accordance with claim 1 , in which cores are inserted (D) in the mould cavities before closing the moulds (5), c h a r a c t e r i z e d by step a) comprising inserting (D) the cores in the first produced mould (5) during production of the second mould (5) and inserting (D) the cores in the second mould (5) after moving the mould string (F) over a distance corresponding to the length occupied by one mould (5) in the mould string (F), thereafter moving the mould string (F) one further step over a distance corresponding to the length occupied by one mould (5) in the mould string (F), whereafter pouring (7) of two moulds (5) can be initiated in step c). 3. Method in accordance with claim 1, in which cores are inserted (D) in the mould cavities before closing the moulds (5), characterized by step a) comprising inserting (D) the cores in the first produced mould (5) during production of the second mould (5) and after delivery of the second mould (5) moving the mould string (F) over a distance corresponding to the length occupied by two moulds (5), whereafter pouring (7) of two moulds (5) can be initiated in accordance with step c) before insertion (D) of the cores in the second mould (5). 4. Mould-string foundry plant for performing the method in accordance with claim 1, said plant comprising a mould-making station (A), a precision conveyor (C) and a pouring station (B), characterized by the precision conveyor (C) being constructed to be able to engage and move the last produced mould (5), when delivered from the mould-making station (A) and the pouring station (B) being constructed to pour metal (7) into two mould cavities simultaneously. 5. Mould-string foundry plant in accordance with claim 4, further comprising a core insertion mechanism (D), c h a ra c t e r i z e d by said core insertion mechanism (D) being constructed to be able to insert cores into the moulds (5) in two different positions, i.e. the position of the first mould (5), when delivered from the mould-making station and the position of the second mould (5) after the advancing of the mould string (F) over a distance corresponding to the length occupied by two moulds (5) in the mould string (F).

Inventors: JACOBSEN OLE ANDERS, JACOBSEN, OLE, ANDERS
Applicants: GEORG FISCHER DISA AS, JACOBSEN OLE ANDERS, GEORG FISCHER DISA A/S, JACOBSEN, OLE, ANDERS
Application year: 2000
Main classification: B22D33
IPC codes: B22C9, B22C11, B22D33, B22D47