Mold transfer assembly

Description

[0001] The present invention relates to the production of cast metal articles, and more specifically, to an apparatus and a method for holding a mold that is being filled and for transferring a mold filled with molten metal from a pouring station while moving an empty mold onto said pouring station.

[0002] In the manufacture of cast metal articles such as railway wheels, it is important from a cost savings and energy savings point of view to produce such wheels as rapidly as possible while maintaining the accuracy necessary to produce near finish castings. A typical wheel casting plant layout is shown in U. S. Patent No. 2,999,281 upon which the preambles of the independent claims 1 and 8 are based. A cope or top mold section is placed on top of a drag or bottom mold section to form a complete mold. Usually the mold is a reusable graphite mold. When the completed mold is moved along a conveyor to a pick up station adjacent the pouring station, a pick-up crane is used to lift the mold and place it on the pouring station above the pouring tank. The mold is located above the pouring tank because a bottom pressure pouring method is used to inject the molten metal into the mold. The ladle containing the molten metal is placed within a pouring tank. The pouring tank is capable of being pressurized with air, thereby forcing the molten metal upwardly through a refractory pouring tube into the bottom of the mold.

[0003] Prior to filling the mold, the mold must be held in place, usually by air cylinders which extend downwardly to contact the cope. Further, a mold stopper assembly must be lowered, again by air cylinder, over the stopper hole in the mold. Finally, a riser height control mechanism must be lowered into the mold riser whereby the height of the molten metal in the riser is determined and hence the pouring operation is automatically controlled. These three mechanisms, the hold down cylinders, the mold stopper and the riser height control mechanism, were previously located on the mold set down crane legs used to pick up the filled mold and transfer it to the mold set down location from where the mold would continue for processing along conveyors.

[0004] The mold set down crane and the mold pick up crane are each comprised of a column assembly having two legs, and both column assemblies are mounted on a single top frame assembly. Such top frame assembly is capable of lateral movements along secondary girders, which secondary girders themselves comprise a crane assembly mounted on main girders giving the secondary girders the capability of moving longitudinally with relation to the pouring station. Because of the mounting of the pick up crane and set down crane on a single top frame assembly, their lateral movements along the secondary girders are simultaneous and of equal lateral dimension.

[0005] In the pouring sequence of the previously known arrangement, a mold just filled with molten metal is at the pouring station and a second, empty mold is at the mold pick up location. The mold hold down assembly, mold stopper and riser height control are attached to the set down crane, and, after pouring is completed, are raised from the mold. The set down crane then raises the filled mold while the pick up crane raises an empty mold. The frame assembly supporting both cranes is moved laterally along the secondary girders. The filled mold is placed at the set down location by the set down crane and the empty mold is placed at the pouring station by the pick up crane. The set down crane and the pick up crane are then moved via their frame assembly laterally along the secondary girders. When the set down crane reaches the pouring station, the mold hold down assembly and riser height control are lowered to the empty mold and the pouring operation begins. The mold stopper is lowered after the mold has been filled.

[0006] From the foregoing it is apparent that it is known to provide a pouring assembly for use in the manufacture of cast metal articles, said assembly comprising a mold transfer apparatus having a top frame mounted on and movable along a bridge structure, two sets of depending legs extending from the top frame and supported thereby, and a pouring tank located at a pouring station under the bridge structure, said pouring tank being capable of being pressurized to permit the upward pouring of molten metal therefrom into a mold positioned thereabove, one set of said depending legs of said mold transfer apparatus being adapted to move an empty mold from a pick up location to said pouring station, and the second set of depending legs of said mold transfer apparatus being adapted simultaneously to move a filled mold from said pouring station to a set down location. In this arrangement, a mold is held at the pouring station during filling thereof by means provided on the second set of depending legs so that filling of the mold cannot commence until these legs have returned to the pouring station.

[0007] According to a first aspect of the invention, the bridge structure includes means arranged to hold said mold independently of said depending legs at said pouring station whereby filling of an empty mold may begin shortly after such is positioned at said pouring station and before the second set of depending legs of the transfer apparatus moves into engagement with the mold.

[0008] In accordance with the invention there are significant time savings as compared with earlier arrangements wherein the mold holding mechanism is mounted to the set down crane or legs since with the inventive arrangement filling of the mold may commence before the set down legs are returned to the pouring station.

[0009] In a preferred embodiment the bridge member further includes a mold stopper closing mechanism and a riser height control, and a mold filled with molten metal is moved from the pouring station by the set down crane after the mold hold down assembly, the mold stopper closing mechanism and the riser height control are lifted from the mold. The filled mold is moved from the pouring station by the set down crane while an empty mold is moved to the pouring station by the mold pick up crane. However, since the mold hold down assembly, the mold stopper closing mechanism and the riser height control are not attached to the set down crane, but rather are attached to, for example, secondary girders of the bridge structure, shortly after the empty mold is placed at the pouring station, the mold hold down assembly, the mold stopper and the riser height control can be lowered onto the mold. The pouring operation can therefore begin before the set down crane is returned to the pouring station. In a preferred embodiment the time savings per casting is about 8 seconds, which, in a plant normally producing 1,000 castings in a 24 hour period, can increase production to about 1,100 castings in a 24 hour period, a 10% increase.

[0010] Viewed from a second aspect the invention provides a method of producing cast metal articles comprising moving a movable frame assembly of a mold transfer apparatus along a bridge structure between first and second positions thereof so as to move a mold filled with molten metal at a pouring station from the pouring station to a set down station where the filled mold is set down, and simultaneously to move an empty mold from a pick up station to said pouring station, and thereafter returning said apparatus to the first position thereof for subsequent like transfer operations, characterised in that each empty mold is held at said pouring station and filling thereof with molten metal is commenced before said transfer apparatus is returned to its first position.

[0011] A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:

[0012] Figure 1 is a front view in partial cross section of a mold handling system, and Figure 2 is a side view along line 2-2 of Figure 1 of the mold handling system.

[0013] A pouring station and mold handling system are shown in Figures 1 and 2 of the drawings. The mold 10 is centrally located at the pouring station, being set atop pouring tank 12 and joined to pouring tank 12 by refractory pouring tube 14. Mold 10 is comprised of top or cope section 16 and bottom or drag section 18. Usually such molds are of a permanent composition, utilizing compressed graphite as the refractory material.

[0014] Set down crane 19 comprises a front depending leg 20 and a rear depending leg (not shown), and pick up crane 25 comprises front depending leg 22 and rear depending leg 62. All said depending legs are supported by top frame assembly 24. Lower section 21 of set down crane front depending leg 20 and a similar lower section of the rear depending leg (not shown), and lower section 23 of pick up crane front depending leg 22 and lower section 64 of rear depending leg 62 are moveable sections supported by compressed air cylinders 50 and 51 within each crane. The pairs of lower section 21 and lower section of crane 19 not shown and lower sections 23 and 64 of crane 25 cooperate to contact and lift a mold assembly 10. Top frame assembly 24 is a beam arrangement which is adapted to move laterally across intermediate support girders 26. Girders 26 can move longitudinally across main support rails 28 and 30.

[0015] Hanging from intermediate support girders 26 are mold hold down cylinders 32 and 34, usually compressed air type piston cylinders, mold stopper 36, usually also a compressed air type cylinder with a refractory stopper, and riser height control mechanism 38. The refractory stopper is usually mounted in the mold and not connected to the cylinder. Riser height control mechanism 38 can be of various types, but usually extend into the mold riser and, upon the detection of molten metal rising to a preset height, will generate a signal to end the pouring of the molten metal.

[0016] Upon the movement of frame assembly 24 to the right in Figure 1, set down crane 19 will be aligned with mold 10 at the pouring station. Filled mold 10 will be picked up by set down crane 19. At the same time, pick up crane 25 will be at a mold pick up station 40, where it will pick up an empty mold. As top frame assembly 24 moves left, the filled mold will be set down at the mold set down station 42. At the same time, pick up crane 25 will be setting the empty mold down at the pouring station. Hold down cylinders 32, 34, and riser height control 38 will be lowered to the empty mold, and pouring of molten metal can begin. Mold stopper 36 is lowered after the mold has been filled. Meanwhile, top frame assembly 24 is moving to the right to prepare for the pick up of the filled mold at the pouring station by set down crane 19 and of an empty mold at pick up station 40 by pick up crane 25.

[0017] Two secondary hold down cylinders 52 and 53 are attached to set down crane front leg 20 and the rear leg (not shown). These cylinders are usually compressed air type piston cylinders. They are used to hold the full mold closed when being transferred from the pouring station 12 to the set down position 42.

Claims

1. A pouring assembly for use in the manufacture of cast metal articles said assembly comprising a mold transfer apparatus having a top frame (24) mounted on and movable along a bridge structure (26), two sets of depending legs (22,62;20) extending from the top frame (24) and supported thereby, and a pouring tank (12) located at a pouring station under the bridge structure (26), said pouring tank (12) being capable of being pressurized to permit the upward pouring of molten metal therefrom into a mold (10) positioned thereabove, one set of depending legs (22,62) of said mold transfer apparatus being adapted to move an empty mold from a pick up location (40) to said pouring station, and the second set of depending legs (20) of said mold transfer apparatus being adapted simultaneously to move a filled mold from said pouring station to a set down location (42), characterised in that said bridge structure (26) includes means (32,34) arranged to hold said mold (10) independently of said depending legs (20,22) at said pouring station whereby filling of an empty mold may begin shortly after such is positioned at said pouring station and before the second set of depending legs (20) of the transfer apparatus moves into engagement with the mold.

2. A pouring assembly as claimed in claim 1 wherein said bridge structure (26) further includes a mold stopper closing mechanism (36).

3. A pouring assembly as claimed in claim 2 wherein said mold stopper (36) is mounted on an air cylinder arranged to extend downwardly from the bridge structure (26) to contact said mold (10).

4. A pouring assembly as claimed in any preceding claim wherein said bridge structure further includes a riser molten metal height control mechanism (38).

5. A pouring assembly as claimed in any preceding claim wherein each said set of depending legs (22,62;20) includes a lifting cylinder (51;50) that enables each set of legs to lift a mold (10).

6. A pouring assembly as claimed in any preceding claim wherein said means to hold said mold (10) at said pouring station includes two air cylinders (32,34) arranged to extend downwardly from said bridge structure (26) to contact said mold.

7. A pouring assembly as claimed in any preceding claim wherein said depending legs (20) adapted to move a full mold to the set down location have secondary hold down air cylinders (52,53) adapted to hold a full mold (10) closed during transfer.

8. A method of producing cast metal articles comprising moving a movable frame (24) of a mold transfer apparatus along a bridge structure (26) between first and second positions thereof so as to move a mold (10) filled with molten metal at a pouring station from the pouring station to a set down station (42) where the filled mold is set down, and simultaneously to move an empty mold from a pick up station (40) to said pouring station, and thereafter returning said apparatus to the first position thereof for subsequent like transfer operations, characterised in that each empty mold (10) is held at said pouring station and filling thereof with molten metal is commenced before said transfer apparatus is returned to its first position.

9. A method as claimed in claim 8 wherein the molten metal is pressure injected into the bottom of the mold (10).

10. A method as claimed in claim 8 or 9 wherein the filling operation further comprises placing a riser height control mechanism (38) in the empty mold (10) and closing a mold stopper (36).

Ansprüche

1. Gießvorrichtung zur Verwendung bei der Herstellung von Metallgußteilen, welche eine Transportvorrichtung für Gießformen aufweist, die einen oberen Rahmen (24), der an einer Brückenkonstruktion (26) angebracht ist und längs dieser beweglich ist, zwei sätze von hängenden schenkeln (22, 62; 20), die sich von dem oberen Rahmen (24) wegerstrecken und von diesem getragen werden, und einen Gießbehälter (12) hat, der sich an einer Gießstation unter der Brückenkonstruktion (26) befindet, wobei der Gießbehälter (12) unter Druck gesetzt werden kann, um zu ermöglichen, daß die Metallschmelze aus diesem in eine darüberliegende Form (10) nach oben geleitet wird, wobei ein satz der hängenden schenkel (22, 62) der Transportvorrichtung für die Gießformen derart beschaffen und ausgelegt ist, daß eine leere Form von einer Aufnahmestelle (40) zu einer Gießstation bewegt wird, und wobei der zweite satz von hängenden schenkeln (20) der Transportvorrichtung für die Gießformen derart beschaffen und ausgelegt ist, daß gleichzeitig eine gefüllte Form von der Gießstation zu einer Absetzstelle (42) bewegt wird, dadurch gekennzeichnet, daß die Brückenkonstruktion (26) Einrichtungen (32, 34) enthält, die derart angeordnet sind, daß sie die Form (10) unabhängig von den hängenden schenkeln (20,22) an der Gießstation hält, wobei ein Füllen einer leeren Form kurz nach der Anordnung an der Gießstation und bevor der zweite satz von hängenden schenkeln (20) der Transportvorrichtung sich in Eingriffszustand mit der Form bewegt, beginnen kann.

2. Gießvorrichtung nach Anspruch 1, bei der die Brückenkonstruktion (26) ferner eine Formverschlußschließeinrichtung (36) enthält.

3. Gießvorrichtung nach Anspruch 2, bei der der Formverschluß (36) an einem Luftzylinder angebracht ist, der derart angeordnet ist, daß er sich von der Brückenkonstruktion (26) nach unten erstreckt, um die Form (10) zu kon taktieren.

4. Gießvorrichtung nach einem der vorangehenden Ansprüche, bei der die Brückenkonstruktion ferner eine Eingußmetallschmelzenhöhensteuereinrichtung (38) enthält.

5. Gießvorrichtung nach einem der vorangehenden Ansprüche, bei der jeder satz von hängenden schenkeln (22, 62; 20) einen Hubzylinder (51; 50) enthält, die ermöglichen, daß jeder Satz von Schenkeln eine Form (10) hebt.

6. Gießvorrichtung nach einem der vorangehenden Ansprüche, bei der die Einrichtung zum Halten der Form (10) an der Gießstation zwei Luftzylinder (32, 34) enthält, die derart angeordnet sind, daß sie sich von der Brückenkonstruktion (26) nach unten erstrecken, um die Form zu kontaktieren.

7. Gießvorrichtung nach einem der vorangehenden Ansprüche, bei der die hängenden Schenkel (20) derart beschaffen und ausgelegt sind, daß eine volle Form zu der Absetzstelle bewegbar ist, wobei zweite Niederhalte-Luftzylinder (52, 53) vorgesehen sind, die derart ausgelegt sind, daß sie die volle Form (10) während des Transports geschlossen halten.

8. Verfahren zur Herstellung von Metallgußteilen, bei dem ein beweglicher Rahmen (24) einer Transportvorrichtung für Gießformen längs einer Brückenkonstruktion (26) zwischen einer ersten und einer zweiten Stellung derart bewegbar ist, daß eine mit Metallschmelze an einer Gießstation gefüllte Form (10) von der Gießstation zu einer Absetzstation (42) bewegt wird, in der die gefüllte Form abgesetzt wird, und bei dem zugleich eine leere Form von einer Aufnahmestation (40) zu einer Gießstation bewegt wird, und bei dem anschließend die Vorrichtung zu der ersten Position zur Ausführung von ähnlichen Transportvorgängen zurückkehrt, dadurch gekennzeichnet, daß jede leere Form (10) an der Gießstation gehalten wird und das Füllen mit der Metallschmelze begonnen wird, bevor die Transportvorrichtung in ihre erste Position zurückgekehrt ist.

9. Verfahren nach Anspruch 8, bei dem die Metallschmelze mittels Druck in den Boden der Form (10) gespritzt wird.

10. Verfahren nach Anspruch 8 oder 9, bei dem der Füllvorgang ferner aufweist, daß eine Eingußmetall schmelzenhöhensteuereinrichtung (38) in der leeren Form (10) angeordnet wird und ein Formverschluß (36) geschlossen wird.

Revendications

1. Ensemble de coulée destiné à être utilisé dans la fabrication d'articles en métal coulé, ledit ensemble comprenant un appareil de transfert de moules ayant un bâti supérieur (24) monté sur une structure (26) en pont et mobile le long de celle-ci, deux jeux de jambes suspendues (22, 62; 20) s'étendant depuis le bâti supérieur (24) et portées par celui-ci, et une cuve (12) de coulée disposée en un poste de coulée au-dessous de la structure (26) en pont, ladite cuve (12) de coulée pouvant être mise sous pression pour permettre la coulée en source du métal en fusion à partir de cette cuve dans un moule (10) disposé au-dessus d'elle, un groupe de jambes suspendues (22, 62) dudit appareil de transfert de moules étant adapté pour déplacer un moule vide depuis un poste de chargement (40) audit poste de coulée et le second groupe de jambes suspendues (20) dudit appareil de transfert de moules étant adapté pour déplacer simultanément un moule rempli à partir dudit poste de coulée jusqu'à un poste de déchargement (42), caractérisé en ce que ladite structure en pont (26) comprend des moyens (32, 34) agencés pour maintenir ledit moule (10) indépendamment desdites jambes suspendues (20, 22) audit poste de coulée, de sorte que le remplissage d'un moule vide peut commencer peu après que celui-ci ait été disposé audit poste de coulée et avant que le second groupe de jambes suspendues (20) de l'appareil de transfert se déplace pour venir en prise avec le moule.

2. Ensemble de coulée suivant la revendication 1 dans lequel ladite structure (26) en pont comprend en outre un mécanisme (36) de fermeture de trou de bouchon de moule.

3. Ensemble de coulée suivant la revendication 2, dans lequel ledit bouchon (36) de moule est monté sur un vérin pneumatique agencé pour s'étendre vers le bas à partir de la structure (26) en pont pour venir en contact avec ledit moule (10).

4. Ensemble de coulée suivant l'une quelconque des revendications précédentes, dans lequel ladite structure en pont comprend en outre un mécanisme (38) de commande de la hauteur du métal en fusion dans un évent.

5. Ensemble de coulée suivant l'une quelconque des revendications précédentes, dans lequel chaque groupe de jambes suspendues (22, 62, 20) comprend un vérin (51, 50) de relevage qui permet à chaque groupe de jambes de relever un moule (10).

6. Ensemble de coulée suivant l'une quelconque des revendications précédentes, dans lequel lesdits moyens pour maintenir ledit moule (10) audit poste de coulée comprennent deux vérins pneumatiques (32, 34) agencés de façon à s'étendre vers le bas à partir de ladite structure (26) en pont pour venir en contact avec ledit moule.

7. Ensemble de coulée suivant l'une quelconque des revendications précédentes, dans lequel lesdites jambes suspendues (20) adaptées pour déplacer un moule plein jusqu'au poste de déchargement comportent des vérins pneumatiques secondaires (52, 53) de maintien adaptés pour maintenir fermé un moule plein (10) pendant le transfert.

8. Procédé de fabrication d'articles en métal coulé comprenant les phases consistant à déplacer un bâti mobile (24) d'un appareil de transfert de moules le long d'une structure (26) en pont entre une première et une seconde positions de façon à déplacer un moule (10) rempli de métal fondu à un poste de coulée à partir de ce poste jusqu'à un poste (42) de déchargement où le moule rempli est déposé, et à déplacer simultanément un moule vide à partir d'un poste (40) de chargement jusqu'audit poste de coulée, et à ramener ensuite ledit appareil dans sa première position pour des opérations succéssives analogues de transfert, procédé caractérisé en ce que chaque moule vide (10) est maintenu audit poste de coulée et en ce que le remplissage du moule de métal en fusion commencé avant que ledit appareil de transfert soit revenu à sa première position.

9. Procédé suivant la revendication 8 dans lequel le métal en fusion est injecté sous pression dans le fond du moule (10).

10. Procédé suivant l'une quelconque des revendications 8 ou 9, dans lequel l'opération de remplissage comprend en outre: la mise en place dans le moule vide (10) d'un mécanisme (38) de commande de la hauteur dans l'évent et la fermeture d'un trou de bouchon (36) du moule.

Drawing