Casting apparatus comrpising an oscillating table

Description

Field of the invention

[0001] This invention relates to an oscillating table, in particular to a table, used for instance in bloom and billet production plants, used to obtain the oscillation of the mould.

Prior art

[0002] Conventional oscillating tables are described in various patent documents. One such document, US4456052, describes a continuous casting apparatus in which a casting mould, mounted in a suitable mounting arrangement, is oscillated by means of oscillation levers. These levers are hinged at one end to the mould mounting arrangement and at the other end to a supporting block. The presence of bearings, and other mechanical parts that are subject to wear, means that the use of such devices is disadvantageous, as they require a great deal of maintenance which is expensive in terms of money and time. Moreover, during the production process some disadvantageous movements of the oscillating table occur as a result of bearing backlash, which increases at higher oscillation frequencies.

[0003] Some of these drawbacks have been overcome by means of new oscillating systems based on the use of leaf springs.

[0004] A document, DE2248066, describes a device in which a mould is guided laterally by two leaf spring assemblies arranged parallel to one another and one above the other. Oscillation is brought about by a hydraulic cylinder. The two spring assemblies, which are arranged one on each side of the mould and clamped in place on one side to the bearing structure and on the other side to the mould, must absorb all the guide forces. The springs are, in actual fact, subjected to tensile as well as axial and bending stresses. On account of this the spring assemblies must be much longer and much thicker than is necessary for the maximum tensile forces that occur. Due to the large size of the spring assemblies, higher drive forces are necessary, that is to say the oscillation drive must be correspondingly larger in size. Moreover, the service life of the spring assemblies is reduced because of the high alternating bending stress occurring due to the large thickness. The use of very long spring assemblies means that there is also a more pronounced elastic behaviour, resulting in greater deflections and deviations of the mould from the desired guide path. Thermal influences are also more noticeable.

[0005] Another document, WO9912676, describes a device in which a mould is supported on a mould-supporting device by means of at least one pair of leaf springs, extending approximately transversely to the direction of oscillation and absorbing forces in the elastic range. At least one first guide element extends from the mould-supporting device towards the mould in a first direction and at least one second guide element extends from the mould-supporting device towards the mould in a direction opposite to the first direction. The leaf springs are arranged in such a way that they are bend-resistant in the directions transverse to the direction of oscillation and bendable in the direction of oscillation, and are only subjected to tensile forces. Said device is thus certainly more compact that those described previously but still has several drawbacks: the use of leaf springs does not enable high precision guidance or the reduction of oscillation marks on the cast product; the oscillating table has poor torsional rigidity; its operation requires the use of mechanical bearings with the drawbacks described above; finally, the oscillation frequency is not easily increased.

[0006] This invention aims to overcome these drawbacks.

Summary of the invention

[0007] One of the main purposes of this invention is to provide an oscillating table that is of a more straightforward design and more compact and that allows greater precision in the guidance of the mould even if the frequency of oscillation is increased. Another purpose is to produce an oscillating table in which there are no mechanical parts subject to wear, to enable a significant reduction in the amount of maintenance required and thus obtain considerable savings in terms of time and money.

[0008] This invention therefore aims to overcome the drawbacks described above with an oscillating table having the characteristics set forth in claim 1.

[0009] The total absence of bearings in the oscillating table according to this invention not only means that the table is maintenance-free but also enables the elimination of all disadvantageous movements caused as a result of bearing clearance, which increases at high oscillation frequencies.

[0010] The oscillation drive mechanism, comprising a hydraulic actuator, advantageously transmits the motion via a spring subjected to bending stress, for example a fitted rod.

[0011] According to one advantageous alternative form of this invention, the body of the hydraulic actuator is also anchored to the floor by means of a fitted spring subjected to bending stress. Thus also the drive mechanism has no mechanical bearings, with the advantages described above.

[0012] Furthermore, the use of simpler guide elements, that no longer consist of leaf springs comprising a plurality of elements that are joined to one another, but of straightforward bars, ensures greater guidance precision and enables a reduction in the oscillation marks on the cast product, a reduction that is even more noticeable when working at higher oscillation frequencies.

[0013] Said guide elements also have a long service life and automatically compensate thermal expansions thus avoiding guide deviations.

[0014] Finally, the presence of an anti-roll device, comprising two or more pairs of bars, for example two pairs, ensures good torsional rigidity of the table. Each bar in each pair has a first end that is fastened to the mobile part of the table and a second end that is fastened to the fixed part, in opposite order in relation to the corresponding ends of the adjacent bar of the same pair. According to the direction of the torsional moment, in the case of two pairs of bars, two bars will be subjected to tensile stress, acting as tension bars, while the other two will be subjected to compressive stress, acting as compression members.

[0015] The dependent claims describe preferred embodiments of the invention.

Brief description of the drawings.

[0016] Further characteristics and advantages of this invention will become clear from the following detailed description of a preferred, but not exclusive, embodiment of an oscillating table that is merely illustrative and not limitative, with the help of the drawings that are attached hereto, in which:

Fig. 1 is a vertical cross-section of the oscillating table according to this invention;

Fig.1a is a large view of a component of the oscillating table of Fig. 1;

Fig. 2 is a cross-section of the plan view of the oscillating table in Fig. 1.

Detailed description of a preferred embodiment of the invention

[0017] With reference to Fig. 1, an oscillating table is illustrated with an external supporting structure 1, that is fixed to the floor.

[0018] In one particularly advantageous alternative embodiment, said structure comprises a single beam that supports the structure on the floor and that in turn comprises all the necessary elements in order to support the various parts that make up the table.

[0019] A mould 3 comprising a cylindrical crystallizer 2 is mounted in the external supporting structure. The oscillating movement of said mould is controlled by an oscillation drive mechanism, comprising a hydraulic actuator 4, via a spring subjected to bending stress 5, for example a fitted rod. Said spring subjected to bending stress 5, is connected at the other end to an element 8, for example a bar or a monolithic beam, integral with the mould 3.

[0020] According to one advantageous alternative embodiment the body of the actuator 4 is also anchored to the floor by means of a spring subjected to bending stress 9, for example a fitted rod. Since there are no mechanical bearings whatsoever in the above-described oscillation drive, all the backlash, characteristic of said components, which are notoriously subject to wear, is eliminated.

[0021] There are elastic guide elements 6, 7 to prevent any deviation of the mould 3 from the predetermined path. Said elements 6, 7, which are oblong in shape, are oriented approximately on radial lines of the arc defined by the cavity of the crystallizer 2 if said cavity is curvilinear; on basically parallel lines if the cavity of the crystallizer is rectilinear.

[0022] In this embodiment of the invention said elastic guide elements advantageously consist of a first pair of upper bars 6 and a second pair of lower bars 7, both pairs having a flat cross-section. The elastic bars 6, 7 must absorb tensile forces only and are therefore arranged so as to be bend-resistant in the directions transversal to the direction of oscillation and bendable in the direction of oscillation. The four bars 6, 7 are fastened to one end of the mould 3, i.e. to the mobile part of the table, by means of fastening devices 10, for example bolts, and at the other end to the external supporting structure 1 by means of fastening devices 11.

[0023] One alternative embodiment provides for the use of leaf springs or springs of a similar type as the elastic elements to guide the mould 3.

[0024] To contrast the torsional moment that occurs on a plane that is basically orthogonal to the casting direction, the table according to this invention advantageously incorporates an anti-roll device, comprising two or more pairs of bars 12. Said bars 12, which are horizontal and arranged in directions that are basically transversal to the elastic guide elements 6, 7, ensure a predetermined torsional rigidity of the table. Each bar in each pair has a first end that is fastened to the mobile part of the table and a second end that is fastened to the fixed part, in opposite order in relation to the corresponding ends of the adjacent bar of the same pair. According to the direction of the torsional moment, in the case of two pairs of bars, two bars will be subjected to tension, acting as tie rods, while the other two will be subjected to compression, acting as struts.

[0025] In another advantageous alternative embodiment there are elastic means 13, for example compression or air or leaf springs, the function of which is to lighten the mould 3 and the actual table structure ensuring a better distribution of the weight.

[0026] Thanks to the total absence of mechanical bearings in the oscillating table according to this invention the table requires no special maintenance, resulting in savings in terms of time and money, and all disadvantageous movements due to bearing play, which increases at higher oscillation frequencies, are eliminated.

[0027] Moreover, the use of much simplified elastic guide elements ensures better precision in mould guidance and results in a reduction in the oscillation marks on the cast product.

[0028] Finally, thanks to the improvements described above, the oscillating table according to this invention is more compact and of a simpler design and can be used at oscillation frequencies of above 4.5 Hz, which is higher than the normal frequencies of 3.5 Hz.

[0029] The specific embodiments described in this document are not limitative and this patent application covers all the alternative embodiments of the invention as set forth in the claims.

Claims

1. A casting apparatus comprising an oscillating table comprising

- a mobile structure, mounted in a supporting structure integral with the floor, wherein the mobile structure comprises a mould (3) defining a first casting direction and being guided in an oscillation by first elastic members (6, 7) having an elongated shape and arranged transversely to the direction of casting,

- a hydraulic actuator (4) transmitting oscillations to the mould (3),

characterized in that there are provided two or more pairs of bars (12), arranged horizontally in a second direction basically transversal to the first elastic members (6, 7) and to the first direction of casting, a first end of each bar of each pair is fastened to the mobile structure and a second end is fastened to the supporting structure, whereby the table is provided with a predetermined torsional rigidity about an axis substantially parallel to the first elastic means.

2. A casting apparatus according to claim 1, wherein each bar (12) of each pair has a first end fastened to the mobile structure and a second end fastened to the supporting structure, in opposite order with respect to the corresponding ends of the other bar in the pair.

3. A casting apparatus according to claim 1, wherein there are provided second elastic members (13) connecting the mould (3) to the supporting structure that lighten the mould (3) and distribute its weight in a uniform manner.

4. A casting apparatus according to claim 1, wherein there is provided a third elastic member (5) clamped in place and connecting the hydraulic actuator (4) to the mould (3).

5. A casting apparatus according to claim 1, wherein there is a fourth elastic member (9) clamped in place and connecting the hydraulic actuator (4) to the floor.

6. A casting apparatus according to claims 4 and 5, wherein said third and fourth elastic members (5, 9) consist of a spring subjected to bending stress.

7. A casting apparatus according to claim 6, wherein said spring subjected to bending stress consists of a fitted rod.

8. A casting apparatus according to claim 3, wherein said second elastic members (13) consist of compression or air or leaf springs.

9. A casting apparatus according to claim 1, wherein said first elastic members (6, 7) consist of bars or leaf springs.

Ansprüche

1. Gießvorrichtung mit einem Schwingtisch, welcher umfasst:

- einen beweglichen Aufbau, welcher in eine Stützstruktur eingebaut ist, die mit dem Fußboden fest verbunden ist, wobei dieser bewegliche Aufbau eine Gießform (3) umfasst, welche eine erste Gießrichtung festlegt und durch erste elastische Teile (6, 7), welche eine längliche Gestalt aufweisen und quer zur Gießrichtung angeordnet sind, in einer Schwingbewegung geführt wird,

- ein hydraulisches Antriebselement (4), welches die Schwingungen auf die Gießform (3) überträgt,

dadurch gekennzeichnet, dass zwei oder mehr als zwei Stangenpaare (12) vorhanden sind, welche horizontal in einer zweiten Richtung grundsätzlich quer zu den ersten elastischen Teilen (6, 7) und zu der ersten Richtung des Gießens angeordnet sind, wobei ein erstes Ende einer jeden Stange eines jeden Stangenpaares an dem beweglichen Aufbau montiert ist und ein zweites Ende an der Stützstruktur befestigt ist, wodurch der Tisch mit einer vorher festgelegten Torsionssteifigkeit um eine Achse, die im Wesentlichen parallel zu den ersten elastischen Mitteln verläuft, ausgestattet wird.

2. Gießvorrichtung nach Anspruch 1, bei welcher jede Stange (12) eines jeden Stangenpaares ein erstes Ende aufweist, welches an dem beweglichen Aufbau befestigt ist, sowie ein zweites Ende, welches an der Stützstruktur in gegenüberliegender Anordnung in Bezug auf die entsprechenden Enden der anderen Stange in dem Stangenpaar befestigt ist.

3. Gießvorrichtung nach Anspruch 1, bei welcher zweite elastische Teile (13) vorhanden sind, welche die Gießform (3) mit der Stützstruktur verbinden, um die Gießform leichter zu machen und ihr Gewicht gleichförmig zu verteilen.

4. Gießvorrichtung nach Anspruch 1, bei welcher ein drittes elastisches Teil (5) vorhanden ist, welches an Ort und Stelle festgeklemmt ist und das hydraulische Antriebselement (4) mit der Gießform (3) verbindet.

5. Gießvorrichtung nach Anspruch 1, bei welcher ein viertes elastisches Teil (9) vorhanden ist, welches an Ort und Stelle festgeklemmt ist und das hydraulische Antriebselement (4) mit dem Fußboden verbindet.

6. Gießvorrichtung nach den Ansprüchen 4 und 5, bei welcher das genannte dritte und vierte elastische Teil (5, 9) aus einer Feder besteht, welche einer Biegespannung ausgesetzt ist.

7. Gießvorrichtung nach Anspruch 6, bei welcher die genannte Feder, welche der Biegespannung ausgesetzt ist, aus einem befestigten Stab besteht.

8. Gießvorrichtung nach Anspruch 3, bei welcher die genannten zweiten elastischen Teile (13) aus Druckfedern oder Luftfedern oder Blattfedern bestehen.

9. Gießvorrichtung nach Anspruch 1, bei welcher die genannten ersten elastischen Teile (6, 7) aus Stangen oder aus Blattfedern bestehen.

Revendications

1. Appareil de coulée comprenant une table oscillante comprenant

- une structure mobile, montée dans une structure de support intégrale avec le plancher, où la structure mobile comprend un moule (3) définissant une première direction de coulée et étant guidé dans une oscillation par de premiers éléments élastiques (6, 7) d'une forme oblongue et agencés transversalement à la direction de la coulée,

- un actionneur hydraulique (4) transmettant les oscillations au moule (3),

caractérisé en ce que sont prévues deux ou plusieurs paires de barres (12), agencées horizontalement dans une deuxième direction essentiellement transversale aux premiers éléments élastiques (6, 7) et à la première direction de coulée, une première extrémité de chaque barre est fixée à la structure mobile, et une deuxième extrémité est fixée à la structure de support, par quoi la table est pourvue d'une rigidité torsionnelle prédéterminée autour d'un axe sensiblement parallèle aux premiers moyens élastiques.

2. Appareil de coulée selon la revendication 1, où chaque barre (12) de chaque paire possède une première extrémité fixée à la structure mobile et une deuxième extrémité fixée à la structure de support, dans l'ordre opposé par rapport aux extrémités correspondantes de l'autre barre dans la paire.

3. Appareil de coulée selon la revendication 1, où sont prévus de seconds éléments élastiques (13) reliant le moule (3) à la structure de support qui allègent le moule (3) et distribuent son poids d'une manière uniforme.

4. Appareil de coulée selon la revendication 1, où est prévu un troisième élément élastique (5) serré en place et reliant l'actionneur hydraulique (4) au moule (3).

5. Appareil de coulée selon la revendication 1, où il y a un quatrième élément élastique (9) serré en place et reliant l'actionneur hydraulique (4) au plancher.

6. Appareil de coulée selon les revendications 4 et 5, où lesdits troisième et quatrième éléments élastiques (5, 9) consistent en un ressort soumis à des contraintes de flexion.

7. Appareil de coulée selon la revendication 6, où ledit ressort soumis à des contraintes de flexion consiste en une tige ajustée.

8. Appareil de coulée selon la revendication 3, où lesdits deuxièmes éléments élastiques (13) consistent en ressorts de compression ou pneumatiques ou à lames.

9. Appareil de coulée selon la revendication 1, où lesdits premiers éléments élastiques (6, 7) sont constitués de ressorts sur barre ou à lames.

Drawing