CHANGING SYSTEM FOR A TUNDISH UNIT, TUNDISH UNIT FOR A CHANGING SYSTEM, ATOMIZATION INSTALLATION AND METHOD FOR ATOMIZING METAL MELT

Abstract

A changing system for a tundish unit of an atomization installation for atomizing metal melts including at least one chamber for accommodating at least one first tundish unit in a working position. The chamber has at least one connection to a charging device and at least one connection to an atomization tower or an atomization shaft, a mechanism for providing at least one second tundish unit in a readiness position within the changing system furthermore including at least one changing station designed as a locked chamber for accommodating and/or introducing and/or removing at least one third tundish unit, and including a displacement system, which is designed so that the introduction and/or removal of at least one tundish unit can take place while one tundish unit is located in the working position.

Claims

1-26. (canceled)

27. A changing system for a tundish unit of an atomization installation for atomizing metal melts, which comprises a tundish container, which receives a sprue and a casting nozzle, and means for heating and/or cooling the sprue and/or the casting nozzle and at least one docking station, which is designed complementary to at least one media coupling of the changing system, in particular for powder-metallurgy purposes, comprising at least one chamber for accommodating at least one first tundish unit in a working position, wherein the chamber has at least one connection to a charging device and at least one connection to an atomization tower or an atomization shaft, means for providing at least one second tundish unit in a readiness position within the changing system furthermore comprising at least one changing station designed as a lock chamber for accommodating and/or introducing and/or removing at least one third tundish unit, and comprising a displacement system, which is designed so that the introduction and/or removal of at least one tundish unit can take place while one tundish unit is located in the working position.

28. The changing system as claimed in claim 27, wherein the displacement system is designed so that the introduction and/or removal of at least one tundish unit can take place while a second and/or further tundish unit is located in a readiness position.

29. The changing system as claimed in claim 27, wherein at least one changing station is connected via a lateral opening to the chamber.

30. The changing system as claimed in claim 27, wherein a plurality of changing stations is provided, each of which is laterally connected to the chamber and of which at least one, preferably all are designed as block chambers.

31. The changing system as claimed in claim 27, wherein a turntable, which is arranged in the chamber and accommodates a plurality of tundish units.

32. The changing system as claimed in claim 31, wherein tundish units arranged on the turntable are rotatable from a working position into multiple readiness positions.

33. The changing system as claimed in claim 31, wherein at least one docking station is assigned to each position of a tundish unit, which is connectable to a docking station designed complementary of a tundish unit.

34. The changing system as claimed in claim 27, wherein at least one changing station has at least one docking station, which is connected to a docking station designed complementary of a tundish unit.

35. The changing system as claimed in claim 27, wherein at least one changing station is designed so it can be evacuated.

36. The changing system as claimed in claim 27, wherein at least one changing station is connectable via a vacuum gate valve to the chamber.

37. The changing system as claimed in claim 27, wherein the connections to the charging device and to the atomization tower or the atomization shaft are designed as vacuum gate valves.

38. The changing system as claimed in claim 27, wherein at least one changing station is designed as a heating station for preheating at least one tundish unit.

39. The changing system as claimed in claim 27, wherein the displacement system comprises linear guides, on or at which the tundish units are movably arranged.

40. A tundish unit for use with a changing system as claimed in claim 27, comprising a tundish container, which accommodates a sprue and a casting nozzle, having means for heating and/or cooling the sprue and/or the casting nozzle and having at least one docking station, which is designed complementary to at least one media coupling of the changing system.

41. The tundish unit as claimed in claim 40, wherein a movable undercarriage, which is designed complementary to the displacement system of the changing system.

42. The tundish unit as claimed in claim 41, wherein the tundish container is vertically movable relative to the undercarriage.

43. The tundish unit as claimed in claim 40, wherein the tundish container is spring mounted on an undercarriage and interacts with a hold-down device of the changing system in the working position.

44. The tundish unit as claimed in claim 40, wherein at least one sliding guide, which interacts with corresponding guide means of the displacement system.

45. The tundish unit as claimed in claim 40, wherein at least one sealing means on the lower side of a nozzle plate of the casting nozzle, which interacts with a sealing surface on a vacuum slide in the area of the lower connection of the chamber.

46. An atomization installation having a changing system and multiple tundish units as claimed in claim 27.

47. The atomization installation as claimed in claim 46 having at least one first atomization tower, which is connectable in a gas-tight manner to a connection of the chamber of the changing system.

48. The atomization installation as claimed in claim 46, wherein at least one second atomization tower, wherein the changing system is alternately connectable to the first or second atomization tower.

49. A method for atomizing metal melt to form a metal powder in an atomization installation having a changing system for multiple tundish units, wherein the method comprises a supply of molten metal from a casting device as a charging device into a first tundish unit in a working position within the changing system and atomizing of the melt through a casting nozzle of the tundish unit into an atomization tower or atomization shaft arranged underneath, while at least one second tundish unit is preheated in a readiness position and at least one third tundish unit is removed from the changing system or is introduced therein characterized by the use of a changing system as claimed in claim 27.

50. The method as claimed in claim 49, wherein the use of at least one tundish unit comprising a tundish container, which accommodates a sprue and a casting nozzle, having means for heating and/or cooling the sprue and/or the casting nozzle and having at least one docking station, which is designed complementary to at least one media coupling of the changing system.

51. The method as claimed in claim 49, wherein the supply of the molten metal is controlled as a function of the metal level in the tundish unit located in the working position.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0042] In the figures:

[0043] FIG. 1 shows a perspective view of an atomization installation according to the invention,

[0044] FIG. 2 shows a perspective view of a first exemplary embodiment of the changing system according to the invention,

[0045] FIG. 3 shows a perspective view of a second exemplary embodiment of the changing system according to the invention,

[0046] FIG. 4 shows a top view of the changing system according to FIG. 2,

[0047] FIG. 5 shows a sectional view through the changing system according to FIG. 4,

[0048] FIG. 6 shows a top view of the changing system according to FIG. 3, and

[0049] FIG. 7 shows a sectional view through a tundish unit according to the invention.

DETAILED DESCRIPTION

[0050] The atomization installation 1 shown in FIG. 1 comprises a changing system 2, which is arranged below a casting device (not shown). The changing system 2 is connected in a vacuum-tight manner to an atomization tower 3, in which liquid metal is atomized to form metal powder for powder-metallurgy purposes. The atomizing takes place under inert gas atmosphere. The powder is then separated from the gas and post-treated. The separation takes place via a cyclone stage 4 and a downstream filter installation 5. The separated metal powder is collected in various powder containers 6 and then supplied to a further use.

[0051] The atomizing of the liquid metal is carried out using a tundish unit 7 shown by way of example in FIG. 7, which comprises a sprue 8 and a casting nozzle 9. The sprue 8 forms an intermediate container for the molten metal, which is continuously supplied from the casting device (not shown) above the changing system 2 of a tundish unit 7. The liquid level within the sprue 8 is detected here by means of laser and/or ultrasound. The control of a stopper rod of the casting device as a function of the liquid level is provided. The tundish unit 7 comprises a tundish container 10 having a refractory lining 11, which encloses the sprue 8. The sprue 8 opens into the casting nozzle 9, which is arranged in a nozzle plate 12. In the illustration according to FIG. 7, the casting nozzle 9 protrudes downward beyond the nozzle plate 12. The casting nozzle 9 can also be incorporated completely into the nozzle plate 12, which can be required with respect to the seal against a vacuum gate valve flange.

[0052] A graphite heater, the resistance heating elements 13 of which are embedded in the refractory lining 11, is provided within the refractory lining 11 of the tundish container 10. The casting nozzle 9 is also partially enclosed by a refractory lining 11, in which resistance heating elements 13 are also embedded, which cause nozzle heating. The tundish unit 7 comprises a gas nozzle 28, which is connected on both sides to an inert gas supply 14. The molten metal exiting from the casting nozzle 9 is atomized by means of the inert gas supplied via the gas nozzle 28 in the atomization tower 3 of the atomization installation 1 to form a powder.

[0053] In the described exemplary embodiment, the tundish container 10 comprises a movable undercarriage, which is only indicated in the drawing. Via the wheels 15 of the tundish container 10, it can be moved on rails 16 of the changing system 2. The tundish container 10 furthermore comprises a ring space 17, to which cooling water can be applied and which forms a cooling jacket, via which the sprue 8 can be cooled as needed. The cooling jacket prevents undesirable co-heating of the process chamber.

[0054] Reference is made hereinafter to FIG. 2, which shows a first exemplary embodiment of the changing system 2 according to the invention. The changing system 2 comprises a chamber 18 closable in a vacuum-tight manner, which has an upper connection 19 to a casting device and a lower connection 20 to the atomization tower 3. Both the upper connection 19 and the lower connection 20 are closable via a vacuum gate valve 21. The upper connection 19 or the relevant vacuum gate valve 21 is provided with an extendable bellows visor, which can be coupled to a compensator or folded bellows on the casting device or a holding furnace of the casting device. The vacuum gate valve 21 of the lower connection 20 is embodied as an atomization shaft gate valve, which also comprises an extendable bellows visor.

[0055] The changing system 2 comprises four changing stations 22, which are each designed as lock chambers and are connected to lateral openings of the chamber 18. The changing stations 22 can each be blocked off in a vacuum-tight or gas-tight manner relative to the chamber 18 via changing gate valves 23. The changing stations 22, which can be completely evacuated and have corresponding connections to a vacuum system, are accessible via removable covers 24. The covers 24 are arranged tightly closable on corresponding openings 25 on the changing stations 22.

[0056] The changing stations 22 are arranged in a cross relative to the chamber 18, which has a circular cross section in the described exemplary embodiment, so that each changing station 22 extends with an angular interval of 90 relative to the adjacent changing station 22 on the circumference of the chamber 18. As already mentioned above, rails 16 (see FIG. 4, for example) on which the tundish units 7 arranged inside the changing system 2 are movable extend through the changing stations 22 and the chamber 18.

[0057] The tundish units 7 are introduced via a crane (not shown) through the openings 25 into the changing stations 22, which are each also designed as a heating station for preheating the tundish units 7 and are each equipped with corresponding media couplings.

[0058] The changing stations 22 are equipped over the entire length with replaceable refractory radiation shields. The changing stations 22 can each be evacuated separately via vacuum pumps and can alternately be flooded with inert gas (argon or nitrogen) or with air. The number of the changing stations 22 results from the required heating time of the refractory lining 11 of the tundish container 7 to a temperature between 1700 and 1800 C. From a temperature of approximately 300 C., the heating of the tundish units 7 can only take place under inert gas, since otherwise the graphite of the tundish container heater would combust. The energy and media supply of the tundish units 7 takes place by means of high pressure hoses for inert gas. The power supply and thermocouple lines are embodied as cables. Cooling water is supplied by means of hoses.

[0059] Electric cylinders or direct drives having variable settable speed and distance measurement systems are provided for the linear movement and positioning of the tundish units 7 within the changing system 2.

[0060] The tundish unit 7 arranged in the chamber 18 in FIG. 2 is located in a working position in which the vacuum gate valves 21 of the upper and lower connections 19, 20 are open. A tundish unit 7 is located in a changing position. The graphite heater of the tundish unit 7 was previously cooled down to temperatures below 300 C. by means of inert gas. The changing gate valve 23 to the relevant changing station 22 is closed.

[0061] Before the cover 24 of the relevant changing station 22 can be opened (the changing station 22 is already shown in the open state in the figure), the changing station 22 is evacuated and flooded with air. After completed changing process, the cover 24 is closed again, it is evacuated, flooded with inert gas, and a temperature-controlled heating process is started. At least two tundish units 7 are each located in a holding position in the other changing stations 22. The heating process takes place in a temperature-controlled manner. As already mentioned above, one tundish unit 7 is located in the working position, i.e., in the atomizing position.

[0062] FIG. 3 shows a second exemplary embodiment according to the invention. Identical components are provided with identical reference signs. The changing system 2 according to the second exemplary embodiment comprises a chamber 18 and a changing station 22 connected via a lateral opening, which can also be separated from the chamber 18 using a changing gate valve 23. The changing station 22 is designed corresponding to the changing stations according to the first exemplary embodiment.

[0063] The exemplary embodiment according to FIG. 3 differs from that according to FIG. 2 in that a turntable 26 is arranged in the chamber 18, on which a plurality of tundish units 7, four tundish units in the described exemplary embodiment, are arranged. The lower connection 20 of the chamber 18 is arranged off center. The turntable 26 can be adjusted around an axis of rotation so that a change of the tundish unit 7 located in the working position into a readiness position takes place, wherein a further tundish unit 7 arranged on the turntable 26 is brought into the working position. For this purpose, the changing gate valve 23 is opened, the tundish unit 7 located in the working position is moved via the rails 16 (not shown in FIG. 3) into the changing station 22, and a tundish unit 7 located in a readiness position is moved into the working position via a rotation of the turntable 26. When the tundish unit 7 is located in the changing position within the changing station 22, the graphite heater is cooled down by means of inert gas, specifically to temperatures below 300 C. The changing gate valve 23 to the chamber 18 is closed in this case. The changing station 22 is then evacuated and flooded with air. After completed changing process, the cover 24 is closed, the changing station 22 is evacuated and flooded with inert gas. The temperature-controlled heating process of the tundish unit 7 is then started. After completed pressure equalization to the chamber 18, the changing gate valve 23 is opened. The inserted tundish unit 7 is positioned linearly on a free space of the turntable 26. The tundish unit 7 is coupled to a media supplied by means of a docking station 27 (only indicated) on the turntable 26. A docking station 27 is assigned to each position on the turntable 26. The tundish units 7 are supplied with media via the docking stations 27. At least two tundish units 7 are located in a readiness position on the turntable 26 in which heating and/or keeping warm up to 1700 C. to 1800 C. takes place. The changing gate valve 23 is normally located in the closed state, it is opened only during removal and equipping of a tundish unit 7 in order to produce the pressure equalization.

[0064] As already mentioned above, a seal between the nozzle plate 12 and the vacuum gate valve 21 is required upon the movement of a tundish unit 7 into the working position. The vacuum gate valve 21 represents the lower connection 20 of the chamber 18. Such a seal can take place by means of corresponding sliding seals or friction seals between the nozzle plate, on the one hand, and a sealing surface to the vacuum gate valve 21, on the other hand.

[0065] Alternatively, it can be provided that the tundish unit 7 is vertically movable and can be lowered into a working position, so that a sealing means on the nozzle plate and/or on the atomization gate valve flange can be engaged with one another here. The tundish unit 7 can be raised and lowered, for example, via pneumatic cylinders operated by inert gas within the rail system. In order to ensure the leak-tightness between the nozzle plate 12 and the vacuum gate valve 21, the tundish unit 7 is lower during the positioning. An alternative embodiment of the tundish unit 7 provides that the tundish unit 7 is spring mounted on wheels and is held in the working position by a hold-down device (not shown) in a sealed position. The hold-down device presses the nozzle plate 12 onto a flange of the vacuum gate valve 21. Upon lifting off of the hold-down device, the tundish unit 7 can automatically detach from the vacuum gate valve 21.

[0066] As schematically shown in FIG. 1, the atomization installation 1 can have multiple atomization towers 3. The changing system 2 can be connected alternately to the one or the other atomization tower 3.

[0067] The atomization towers 3 are water cooled. Moreover, they can additionally be equipped with electrical water preheating.

LIST OF REFERENCE NUMERALS

[0068] 1 atomization installation [0069] 2 changing system [0070] 3 atomization tower [0071] 4 cyclone stage [0072] 5 filter installation [0073] 6 powder container [0074] 7 tundish unit [0075] 8 sprue [0076] 9 casting nozzle [0077] 10 tundish container [0078] 11 refractory lining [0079] 12 nozzle plate [0080] 13 resistance heating element [0081] 14 inert gas supply [0082] 15 wheels [0083] 16 rails [0084] 17 ring space [0085] 18 chamber [0086] 19 upper connection of the chamber [0087] 20 lower connection of the chamber [0088] 21 vacuum gate valve [0089] 22 changing station [0090] 23 changing gate valve [0091] 24 cover [0092] 25 opening [0093] 26 turntable [0094] 27 docking stations [0095] 28 gas nozzle