POWDER FEEDER IN CONTINUOUS CASTING

Abstract: This invention relates to an improvement in a powder feeder in continuous casting according to which the feeder can be disposed on an operator side. This powder feeder is equipped with a powder container for storing cast powder of a final stage to be supplied onto the surface of a molten steel present in a mold and a spreader feeder for spreading this cast powder on this surface. The powder container is disposed at a high position above the work space of the mold and the spreader feeder is fitted to a robot arm. The feeder and the discharge port of the container are interconnected through a flexible transfer path which can follow the movement of the robot arm.

Description: The invention relates to a powder feeder in continuous casting according to the preamble of claim 1. The applicant has proposed a powder feeder in which each discharge port of a plurality of powder storage hoppers is connected to a final-stage powder container for mixing powder through a spring feeder, and the one end of the spring feeder provided with an oscillating mechanism is connected to the discharge port of the final-stage powder container, and the other end of the spring feeder meets the powder receiver in front of the final-stage powder container as a free end, and said spring feeder is arranged so as to achieve return movement back and forth relative to the powder receiver (Japanese Patent Publication No. 57-54228). The applicant has also proposed a tundish car which is mounted with a powder feeder in which a pair of spring feeders is equipped, and the ends of pipe assemblies extending from the base assemblies of the spring feeders are swung in the horizontal reverse directions each other near the strand nozzles, to make the spreading of the casting powder better (Japanese Patent Publication No. 61-11703). However, the conventional powder feeder is provided with the final-stage powder container inevitably in the same height as the work space of the mold. That is, since the one end of the spring feeder provided with the oscillating mechanism is connected to the discharge port of the final-stage powder container and the other end of the spring feeder is met as a free end to the powder receiver in front of the final-stage powder container, the final-stage powder container is inevitably placed in the same height as the mold and the tundish. The final-stage powder container thus provided in the same height as the molding height is an obstacle to the molding operation. To prevent this, the powder feeder including the final-stage powder container is arranged in the opposite side to an operator of the mold. However, in the opposite side of the continuous casting machine to an operator, scattering of dust and molten steel occur much causing unparalleled bad environment producing many troubles. In addition, the maintenance work under the bad environment is very difficult and has a problem in safety. Further, relatively simple motion such as swinging of the conventional spring feeder only causes a dead angle in spreading to the mold, though various improvements have been made on the spreading of the casting powder. To remove this dead angle, many precision machines must be used, but the use is difficult in such a bad environment as the above. FR-A-2 407 773 discloses a powder feeder comprising a powder-spreading tube which is pivotally carried by a tundish car so that the tube can swing across the surface of the molten steel in the mold. A powder container mounted on a raised plateform is associated with a screw feeder which discharges powder into a funnel at the upper end of the powder-spreading tube. This powder feeder does not solve the above-mentioned problems. JP-A-60-49846 discloses a powder feeder comprising a powder-spreading tube supported and manipulated by a robot arm mounted on a fixed base near the mold. Powder is driven by a metering pump through a flexible line connecting the spreading tube to a powder container mounted at a fixed location near the mold. An infra-red camera for monitoring the condition of the powder-covered surface of the molten steel is mounted above the mold. Again, this powder feeder does not solve the above-mentioned problems. The present invention provides a powder feeder for use in continuous casting, comprising a powder container for storing final stage casting powder prior to spreading on the surface of molten steel in a mold, metering means, associated with the powder container, for measuring the quantity of powder discharged by the container, a spreading feeder for spreading the powder on the surface of the molten steel in the mold, a robot arm for supporting and manipulating the spreading feeder, and a flexible transfer path connecting a discharge port of the powder container to the spreading feeder and being capable of following the movement of the robot arm, characterised in that the powder container and the metering means are carried by a revolving cantilever arm supported by a column in an operator work area, the powder container, the metering means, and the cantilever arm are above head height, the robot arm is supported by the cantilever arm, and the spreading feeder is at a lower level than the powder container so that the powder flows downwardly along the flexible transfer path. Arranging a spreading conditions monitoring sensor on the above robot arm solves the above-mentioned problems much better. The powder container for storing final stage casting powder refers to the second powder container in a configuration in which the powder is transferred from a first powder storage container to a second powder container and spread on the mold from these. In a configuration in which the powder is directly spread on the mold from a first powder storage container, this container is the powder container for storing final stage casting powder. A robot arm comprises a plurality of sections movably connected through joints and the movement of each section is automatically controllable. The spreading feeder may comprise a pneumatic transfer means or a mechanical transfer means such as a spring feeder. The sensor for monitoring the spreading conditions on the molten steel surface in the mold may comprise an infrared sensor or thermal sensor for detecting a molten steel exposed section (hot spot). Since the final-stage powder container is arranged above head height in the operator work area in the powder feeder according to the invention, arranging the monitoring sensor on the operator side does not impair the operation of an operator. Thus, the powder feeder provided with the robot arm, a precision control instrument, can be arranged on the operator side, in better environment than the side opposite an operator. Furthermore, the flexibility of the robot arm permits removal of the dead angle on the spreading surface of the mold. A sensor arranged on the robot arm for monitoring the spreading conditions of casting powder can detect the exposed molten steel part (hot spot). Based on the detection of the sensor, the robot arm is automatically controlled to move the end of the spreading feeder to the hot spot for spreading the casting powder. In the accompanying drawings: Figure 1 is a front elevation of an embodiment according to the invention, and Figure 2 is a plan view of the same. With reference to the drawings, a preferred embodiment of the present invention is described. Figure 1 is a front elevation of an embodiment and Figure 2 is a plan view of the same. The powder feeder comprises a final-stage powder container 1, a spreading feeder 2, and a multi-joint robot arm 3. The final-stage powder container 1 has a powder inlet line 13 and is mounted on the end of a revolving cantilever arm 12 held on the top of a column 11, more particularly, it is mounted at a position closer to the base end of an arm extension 12a. The revolving arm 12 and extension 12a are adequately driven by a driving device (not shown). Here, the column 11 is taller than the height of an operator a and arranges the revolving arm 12 and the final-stage powder container 1 above the working space adjacent to a mold 4. Thus, the final-stage powder container 1 can be arranged on the operator side A, overhead of an operator. In Fig. 2, two final-stage powder containers are arranged on the operator side; B indicates the side opposite an operator. A final-stage powder container 1 is provided with a meter such as a load cell platform scale 14 to weight the spread quantity of the casting powder. Particularly, the use of the "loss-in-weight" system permits recording of accurate spreading quantity and higher accuracy of control by a main computer of the continuous casting unit. The robot arm 3 comprises a base end arm 31, an intermediate arm 32, and a hand 33, movably connected by a first joint 34 and a second joint 35. The base end arm 31 is attached to the end of the extension 12a of the revolving arm 12. The hand 33 carries a spreading feeder 2. The spreading feeder 2 rotates a spring in a tube by a motor 21 mounted at its base end to spread the casting powder from its tip onto the surface of the molten steel in the mold. Instead of such mechanical means, the other transfer means such as pneumatic transfer means can also be used. The molten steel is supplied from a ladle 7 to a tundish 6 with a nozzle 6a, mounted on a tundish car 5. On the distal end of the intermediate arm 32 of the multi-joint robot arm 3, a sensor 9 for monitoring the spreading conditions of the casting powder is arranged. This sensor 9 is specifically an infrared sensor or thermal sensor, and used for detecting exposed molten steel (hot spot) in the mold 4. Based on the detection by the sensor 9, the multi-joint robot arm 3 is moved under automatic control of a computer to move the tip of the spreading feeder 2 to the hot spot for spreading casting powder. It is also possible to move the robot arm 3 according to a predetermined program for spreading, not using such a sensor. The base end of the spreading feeder 2 and the discharge port of the final-stage powder container 1 are connected by a flexible transfer path 8, which is a transfer path having a degree of freedom sufficient to follow the movement of the robot arm, such as flexible pipe. Therefore, non-flexible pipe may be used along part of the transfer path, provided that the required degree of freedom is maintained. The flexible transfer path 8 is arranged from the discharge port of the powder container 1 above the arm extension 12a and along the robot arm 3 to the spreading feeder 2. However, to simplify the drawing, the illustration of the part along the robot arm 3 is omitted. It is possible to provide a powder feeding device in the part the flexible transfer path along the arm extension 12a. The casting powder is transferred by the said feeding device (if provided) and by gravity from the final-stage container 1 to the spreading feeder 2. This gravity feed is based on the energy saving concept using the height difference between the final-stage powder container 1 arranged in a high position and the spreading feeder 2 placed in a low position, but forced transfer means can be added, if necessary. Use and operation of this embodiment will now be described. (i) When the tundish car 5 stops at the position above the mold 4, the revolving arm 12 swings to move the feeder from a stand-by position I to a feed position II. (ii) The extension 12a of the revolving arm 12 turns to face the powder feeder towards the mold 4. (iii) The robot arm 3 moves the tip of the spreading feeder 2 above a hot spot to spread the casing powder from its tip. In Fig. 2, the shaded area b indicates the spreading area. (iv) In replacing the tundish 6, the powder feeder is returned to the stand-by position I by the reverse operation of steps (i) and (ii) mentioned above. The flexibility of the multi-joint robot arm 3 avoids any dead angle above the mold surface and it is easy to avoid contact between the spreading feeder 2 and the tundish nozzle 6a, when the powder feeder is moved. Since the final-stage powder container is arranged in a position higher than the working space, provision of this powder feeder on the operator side does not interfere with the work of an operator. Since conditions on the operator side are better than on the opposite side, the following effects are obtained: (i) Sharp decrease in trouble due to scattered dust and molten steel. (ii) Increased ease of maintenance (fewer maintenance personnel) and safety. (iii) Improved environment makes the use of precision instruments possible. (iv) The easy installation work shortens the construction period. (v) The smaller distance to the control board or the operation board makes the anti-nozzle provision for CPU wiring easier. In spreading the casting powder on the mold, the flexibility of the robot arm avoids any dead angle on the spreading surface of the mold, and the powder is uniformly spread all over the mold surface. The precision instruments and control equipment used in the robot arm can continue good operation in the good environment as described in the item (iii) mentioned above. The provision of the spreading conditions monitor sensor on the robot arm, makes complete automation of hot spot detection and spreading possible by computer control of the spreading. This promotes labour saving, stabilizes the continuous casting, and improves the quality. This invention can be used in full automation of continuous casting. In further progress of continuous casting of high grade steel, a powder feeder in continuous casting has been provided which can cope with feed automation of high grade steel billet size casting powder use.

Claims: A powder feeder for use in continuous casting, comprising a powder container (1) for storing final stage casting powder prior to spreading on the surface of molten steel in a mold (4), metering means (14), associated with the powder container (1), for measuring the quantity of powder discharged by the container (1), a spreading feeder (2) for spreading the powder on the surface of the molten steel in the mold (4), a robot arm (3) for supporting and manipulating the spreading feeder (2), and a flexible transfer path (8) connecting a discharge port of the powder container (1) to the spreading feeder (2) and being capable of following the movement of the robot arm (3), characterised in that the powder container (1) and the metering means (14) are carried by a revolving cantilever arm (12) supported by a column (11) in an operator work area, the powder container (1), the metering means (14), and the cantilever arm (12) are above head height, the robot arm (3) is supported by the cantilever arm (12), and the spreading feeder (2) is at a lower level than the powder container (1) so that the powder flows downwardly along the flexible transfer path (8). A powder feeder as claimed in claim 1, in which the robot arm (3) carries a sensor (9) for monitoring spreading conditions. A powder feeder as claimed in claim 1 or 2, in which the robot arm (3) comprises a base end arm (31) attached to the cantilever arm (12), an intermediate arm (32) connected to the base end arm (31) by a first joint (34), and a hand (33) connected to the intermediate arm (32) by a second joint (35), the spreading feeder (2) being carried by the hand (33). A powder feeder as claimed in any preceding claim, in which the spreading feeder (2) comprises a tube and transfer means for conveying the powder along the tube. A powder feeder as claimed in any preceding claim, in which the transfer means comprises a spring which rotates in the tube and is driven by a motor (21). A powder feeder as claimed in any preceding claim, in which the powder is fed along the flexible transfer path (8) by gravity alone.

Inventors: NAKAJIMA HIROMI, NAKAJIMA, HIROMI
Applicants: LINER LINER CORP KK, MITSUI BUSSAN, KABUSHIKI KAISHA LINER (LINER CORPORATION), MITSUI & CO., LTD.
Application year: 1989
Main classification: B22D11
IPC codes: B22D11