US3060055A

US3060055A - Method and apparatus for accreting molten material

Info

Publication number: US3060055A
Application number: US55471A
Authority: US
Inventors: Harley H Bixler
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1960-09-12
Filing date: 1960-09-12
Publication date: 1962-10-23
Anticipated expiration: 1979-10-23

Description

H. H. BlXLER Oct. 23, 1962 METHOD AND APPARATUS FOR ACCRETING MOLTEN MATERIAL Filed seiat. 12, 1960 w 5Q W l ven 60r- .by W 4. $140 His Attorney United States Patent This invention relates to a method and apparatus for accreting molten material on a moving member, and more particularly, to a method and apparatus for initiating and terminating an accretion process to form a member of substantially uniform composition.

Heretofore, a large portion of the cost of manufacturing stock materials such as rod, tube and sheet was incurred in the manufacture of primary and intermediate forms of material from which the stock material is ultimately manufactured. For example, in the manufacture of copper wire, special equipment such as melting furnaces, rolling equipment, pickling apparatus, etc., are utilized to produce intermediate wire rod stock which is drawn into other shapes of appropriate size by means of conventional apparatus.

An apparatus and a method for continuously depositing by accretion, molten material upon an elongated body having a first cross-sectional configuration of a material having substantially the same composition as the molten material whereby there is formed an elongated body having a second cross-sectional area greater than the first, are disclosed in and said apparatus is claimed in US. Patent No. 3,008,201, which issued from copending application of Roland P. Carreker, Jr., Serial No. 530,283, filed August 24, 1955. The method is claimed in copending application of Roland P. Carreker, lr., Serial No. 98,087, filed March 24, 1961, as a continuation-in-part of said application Serial No. 530,283. This general method is further disclosed and claimed in a more specific and particular form in copending application Serial No. 55,469, filed September 12, 1960, in the names of Roland P. Carreker, Jr., and Robert M. Parke and entitled Method and Apparatus for Accreting Molten Copper on a Moving Member. These applications and this patent were assigned to and are presently owned by the assignee of the present invention. By this means, the use of intermediate steps such as reheating, rolling, pickling, etc., is obviated thereby achieving lower production costs based on lower equipment costs and lower operating costs. In accreting material on a non-ferrous rod, it is normally necessary to introduce the rod into the lower portion of a crucible through a suitable nozzle therein for passing the rod in an upwardly and substantially vertical direction through the molten material in the crucible. Great difiiculty has been experienced in initiating such an accretion process because of the tendency of the rod passing through the crucible to deteriorate because of the high temperature and also because of hydraulic pressure urging the molten material in the crucible into the space between the nozzle surface and the rod as the material enters the crucible. This material tends to either bond itself to the nozzle and the rod in the space therebetween or to mechanically lock with the surfaces thereby restraining the rod from passing through the crucible resulting in the ultimate deterioration of the rod in the crucible by melting.

The chief object of the present invention is to provide an improved method and apparatus for initiating the accretion of molten material on a moving member.

Another object of the invention is to provide a method and apparatus for initiating the accretion of molten material on a moving member in a manner to permit continuous movement of the member through the crucible wherein the accretion process takes place.

Cir

A still further object is to provide a method and apparatus for initiating and terminating accretion of molten material on a moving member wherein the process is inaugurated without any interference of the molten material with the member being introduced into the crucible and wherein the process is terminated in a manner wherein the entire body of molten material in the crucible is removed therefrom permitting re-initiation of the accretion process with facility.

These and other objects of my invention will be more apparent from the following description.

Briefly stated, the present invention relates to initiating and terminating the accretion of molten material on a continuously moving member wherein the member is initially cleaned, passed from the atmosphere into an evacuated passage, introduced into a nozzle located in the lower portion of the crucible, the member being continuously passed in a substantially upward and substantially vertical direction through the crucible, the temperature in the crucible being increased to the melting temperature of the member at which time molten material is introduced into the crucible whereby the molten material accretes on the member to form a member having greater thickness, the supply of molten material being terminated and the supply of material located in the crucible being removed by accretion on the moving member, the temperature in the crucible being decreased and the supply of the member being terminated.

The attached drawings illustrate a preferred embodiment of the invention in Which:

FiGURE 1 is a perspective view partially in section of an apparatus for practicing the present invention; and

FlGURE 2 is a sectional view of a portion of the crucible shown in FIGURE 1 illustrating the area through which the member is introduced into the crucible.

In FIGURE 1, there is shown a preferred embodiment of an apparatus for practicing the present invention in which wire core rod 2 is supplied to a drawing apparatus 3 located adjacent a suitable shaving apparatus 4. The dies of apparatus 3 may support the core rod as it is introduced into a shaving cutter which removes a thin layer of metal from around the entire periphery of the rod to remove the oxide coating or other contaminants therefrom and also to be in sufficiently intimate contact therewith to form a seal between the shaving cutter and core rod. The construction and manner of operation of drawing apparatus 3 and shaving apparatus 4 are more fully described in the copending application of J. A. Russell and G. Carlson, Serial No. 55,470, filed Sept. 12, 1960, entitled, Method and Apparatus for Accreting Molten Material on a Moving Member. If desired, other cleaning means, such as the chemical cleaning means, may be utilized for removing the oxide coating from the surface of the rod.

Core rod 2 having been cleaned enters into a passage partially defined by tube 5. This passage, which is maintained in an evacuated condition by the previously described seal between the shaving cutter and the rod, is provided to assure that the surface of the rod is free from oxidation when the accretion process occurs. The rod passes into idler pulley housing 6 which has located therein a rotatably mounted pulley 7 which changes the direction of rod 2 permitting it to pass into housing 8 wherein is located suitable drive means for urging the rod through the evacuated passage defined by tube 5, housings 6 and 8 and tube 25. This drive means which includes drive rolls or pulleys 9 and 10 is located in the evacuated passage because rod drawing apparatus 3 and rod shaving apparatus 4 require that the rod be pulled therethrough.

Rotative motion is applied to the pulleys by suitable drive means (not shown) connected to shaft extending from gear reducer 16. One output from gear reducer 16 is shaft 17 which is connected to drive roll 19. Drive roll 9 is mounted upon shaft and is connected by means of gears 18 and 19 to shaft 17. By this means drive rolls 9 and 10 rotate in opposite directions to urge rod 2 in an upward direction. Suitable shaft seals may be provided around shafts 1 7 and 19 to maintain the evacuated condition of the passage.

Gear reducer 16 has a second output shaft 21 confiected to gear box 22 having an output shaft 23 which is connected to a second drive means more fully described hereinafter.

In housing 8 there is also located a plurality of pulleys 11 which engage the rod to perform a supporting and straightening function before the rod is introduced into crucible 26. The rod passes from housing 8- into tube 25 which may have connected thereto an exhaust tube 27 connected to such means as an evacuating pump to maintain a vacuum in the passage defined by

members

5, 6, 8, and 25. At the upper end of tube 25 there is located a nozzle 29 which extends into crucible 26 (also shown in FIGURE 2). It can be seen from FIGURE 1 that rod 2, having been shaved to provide a clean surface thereon, is maintained in an evacuated passage and is not permitted to come into contact with an oxidizing atmosphere until after the accretion process has been performed. The clean rod is introduced into nozzle 29 and then into crucible 26 which has located therein a suitable refractory liner 28 which may be fabricated of graphite. Crucible 26 may be insulated to maintain the temperature of molten material 30 located in liner 28. In order to maintain the temperature of the crucible at a desired level, heating means such as electric heater 36 may be utilized. The material supplied to the crucible may be provided by a furnace 31, having heating means (not shown) for melting the copper or other material to be accreted. If desired, gases, such as oxygen, may be removed from the copper by means of a piece of graphite placed in the melt which unites with the gases permitting the production of copper having low oxygen content. The molten material, such as copper, is supplied to crucible 26 by means of a spout 33 which extends into liner 28 of crucible 26. The level in the liner may be sensed by a suitable control means 38 which may also incorporate therein means to sense the temperature in the crucible, control means 38 regulating servo motor 37. Servo motor 37 is connected by means of rod 35 to the previously mentioned piece of graphite 34-. This piece of graphite is of such size that movement thereof in the body of molten material 32 in furnace 31 controls the level and feed of material into crucible 26. Before initiation of the accretion process, this piece of graphite 34 is totally removed from the body of material 32. When it is desired to introduce molten material into the crucible the graphite piece may be immersed into the body of material 32 by servo motor 37 in response to control means 38. The method of operation for initiating the accretion process is more fully described hereinafter.

It has been found that, in order to have proper accretion without a deterioration of the rod and also to prevent back-flow of copper into the peripheral area between the rod and nozzle 29, the speed of the rod should exceed a predetermined value. In accreting material on the rod, it is desirable to maintain a non-oxidizing atmosphere above the level of the liquid. This may be achieved by introducing through line 41 an inert gas above the level of the melt.

The red as it passes through the melt extracts heat from the molten material. This molten material accretes or condenses thereon causing the rod to increase in diameter also expanding the rod due to the increased temperature thereof. The rod is discharged from the crucible through nozzle 43. If desired, suitable cooling means 44, such as spray nozzles, may be utilized to cool the highly heated rod as it leaves the crucible.

The rod emerging from the crucible is in a highly heated, almost plastic, state and is extremely fragile. In order to prevent rupture of the rod, a suitable shock isolation loop 45 may be provided. This construction may change the direction of the rod at an angle greater than Shock isolation loop construction 45 comprises a suitable arm 46, which pivots about a shaft axis 47. The arm has located thereon a plurality of pulleys 43 which because of counter weight 49, located on an extension of arm 46, causes a bias on the rod. The reaction of the moving rod causes rotation of arm 46 in a manner whereby valve 50 is actuated. Pneumatic valve 50 is connected by means of line 51 to a suitable source of pneumatic pressure and is adapted to control an air motor 52 associated with second drive means for driving the rod from the isolation loop in a manner more fully described hereinafter.

As previously mentioned the rod emerging from the crucible is of an increased cross-sectional area because of the accretion of metal thereon. This metal is firmly bonded to the rod partially because of the clean surface pre sented when the rod was introduced initially in the crucible. Because of thermal expansion, the rod length is substantially increased and compensating means must be incorporated in the driving means for removing the rod from the discharge side of the crucible. The previously described arm 46 with its connection to valve 56 comprises a sensing means associated with drive rolls 55 and 56 located adjacent the shock isolation loop. Power is supplied to drive rolls 55 and 56 through the previously described shaft 23 which is associated with the first drive means including rolls 9 and 19. Rotation of shaft 23 is transmitted through gear box 60, through

sprockets

61 and 62 which are connected by a suitable chain 63. Sprocket 62 is mounted on driving shaft 71 which drives difierential mechanism 64. The output of differential mechanism 64 is connected to shaft 65 upon which is mounted drive roll 55. Drive roll 56 is driven by shaft 65 through

gears

66 and 67. In order to vary the speed of drive rolls 55 and 56, air motor 52 is associated with differential mechanism 64 through driving shaft 72. The speed of air motor 52 is controlled by the previously mentioned valve 50 connected to the air motor by means of lines 63 and 69. Manipulation of valve 5i) causes rotation of shaft 72 in either direction to control the speed of rolls 55 and 56. The nature of this differential mechanism is more fully described in the previously mentioned copending application of Russell and Carlson. For purposes of support, a plurality of rolls 7e are provided adjacent drive rolls 55 and 56.

In the operation of the apparatus shown in FIGURES l and 2, a continuous core rod is introduced into drawing apparatus 3, then into shaving apparatus 4 wherein the surface of the rod has the oxide coating or other material removed from the surface thereof, the intimate contact of the cutter with the rod forming a seal between the atmosphere and the evacuated passage starting at tube 5 and terminating at tube 25.

The core rod passes through tube 5 which is in sealing engagement with shaving apparatus 4 and housing 6. The rod passes through housing 6 around pulley 7 and is engaged by pulleys 9 and '10 in housing 8. These pulleys urge the rod up through the housing and also pull the rod through the drawing and shaving operations previously described. As the rod passes through housing 8, it is supported by suitable pulleys 11. The rod enters tube 25 and nozzle 29, at this point the surface of the rod is not only clean from oxidation but the surface of the rod has also been substantially degassed.

When the process is initiated, the rod is introduced into empty crucible liner 23. The temperature of the crucible is increased by heating means 36 to a temperature of 800 C. if both the core rod and the material to be deposited thereon are copper. At this temperature the rod is passed slowly through the crucible, for example, at a speed of between one and two feet per minute. This movement prevents any undue softening or melting of the input rod as the temperature or" the crucible rises above the melting point of the copper or other material being accreted.

When a temperature approximately the melting temperature of the rod is achieved in the crucible, the speed of the input rod is increased to a speed to insure that the rod is not deteriorated during the accreting process by the molten material and also to prevent passage of material into the nozzle to harmfully affect the process. After this speed is achieved, control means 38 actuates servo motor 37 to immerse graphite piece 34 into the poo-l of molten material 32 in furnace 31. This causes material to flow through spout 33 into liner 28 until the proper level of material is supplied and maintained in liner 28. While, because of hydraulic pressure, the molten material tends to run into clearance 29' between rod 2 and nozzle 29 shown in FIGURE 2, the speed of the rod through the nozzle coupled with the surface tension of the molten material causes a meniscus to form between the rapidly moving rod and the molten material which prevents the material running down and freezing in the clearance space. Slight momentary freezing may occur but locking is prevented by the relatively high speed of the rod. As the level of the copper or other material in the crucible increases, rod of larger diameter is formed by the accretion process.

As the process continues, the core rod which is at ambient temperature has accreted thereon a layer of molten material forming a rod substantially homogeneous in character and of greater diameter than the initially fed rod. The rod emerging from molten material 3! is in a substantially glowing state. An atmosphere of inert gas is maintained above molten material St to prevent oxidation in the crucible. Rod 2 passes through nozzle 43 and is discharged from the crucible. If desired, suitable cooling means 4 may be employed at this point to lower the temperature of the rod.

The rod encounters shock isolation loop 45 which because of the bias of counter weight 49 urges pulleys 48 mounted on the arm to engage the high temperature rod whose length has been increased by thermal expansion and Whose cross-sectional area has been increased by accretion. Opposing the bias of counter weight 49 is the driving elfect of drive rolls 55 and 56 which attempts to remove the rod as it is discharged from the crucible. Because of the fragile nature of the rod at this point, the driving speed of drive rolls 55 and 56 is varied in response to the force applied to pulleys 48 by the rod in the shock isolation loop. Movement of the pulleys causes rotation of shaft 47 which controls valve 5%. Air from valve 50 passes through

lines

68 and 69 which varies the speed and direction rotation of output shaft 7 2 of motor 52.

As previously noted, rotational motion is transmitted from shaft through shaft 23, gear box 6%, and pulleys 61 and 62 to shaft 71 which is the driving shaft to the differential mechanism 64. If air motor 52 is not in operation, there is no increase or decrease in the rotational speed of driven shaft 65 over driving shaft '71. Passage of air through either

line

68 or 69 determines the direction of rotation of air motor 52. The direction of rotation of output shaft 72 of air motor 52 determines whether the speed of drive rolls 55 and 56 is less or greater than the speed of the pulleys 9 and It The rod is then guided through pulleys 70' to a suitable storage area from whence the rod is directed to other drawing means as desired.

To terminate the accretion process, the molten material supply is terminated. For example, in the particular embodiment of FIGURE 1 graphite piece 34 is withdrawn from material 32 in furnace 31. This causes a drop in level in furnace 31 so that no material flows through spout 33 into crucible 26. Accretion on the rod continues until the supply of material in crucible as is exhausted. The input rod speed is reduced to approximately one to two feet per minute and the supply of heat from heating means 36 is terminated. The supply of rod is terminated when the crucible temperature reaches approximately 800 C. (for copper). The system is now in its original condition when the accretion process was first initiated.

The present invention provides a method for initiating and terminatnig an accretion process wherein the dithculties of having the molten material freeze to prevent initiation or satisfactory termination of the process are avoided so that the process may be readily started at a future time.

While I have described the preferred embodiment of the invention, it will be understood that the invention is not limited thereto since it may otherwise be embodied within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a method for accreting molten material on a member, the steps which consist in introducing the member into a nozzle located in the lower portion of a crucible, increasing the temperature in the crucible, passing the member continuously through the crucible, increasing the speed of the continuously moving member when the melting temperature of the member is reached in the crucible, introducing molten material into the crucible whereby the molten material accretes on the moving member to form a member of greater thickness.

2. In a method for accreting molten material on a member the steps which consist in introducing the member into a nozzle located in the lower portion of a crucible, increasing the temperature in the crucible, passing the member continuously through the crucible, introducing molten material into the crucible when the melting temperature of the member is attained in the crucible whereby the molten material accretes on the moving member to form a member having greater thickness.

3. In a method for accreting molten copper on a member the steps which consist in introducing the member into a nozzle located in the lower portion of a crucible, increasing the temperature in the crucible, increasing the speed of the continuously moving member to a speed suihcient to prevent deterioration of the rod if molten copper were accreted on the rod when the melting temperature of the member is attained in the crucible, introducing molten copper into the crucible whereby the molten copper accretes on the moving member to form a member having greater thickness.

4. In a method for accreting molten copper on a copper member the steps which consist in introducing the copper member into a nozzle located in the lower portion of a crucible, increasing the temperature in the crucible, passing the copper member continuously through the crucible at a speed suthcient to prevent deterioration of the rod if molten copper were accreted on the rod when the melting temperature of the copper member is reached, introducing molten copper into the crucible when the temperature of the crucible reaches the melting temperature of the copper member whereby the molten copper accretes on the moving copper member to form a member having greater thickness.

5. In a method for accreting molten material on a member the steps which consist in cleaning the surface of the member, passing the member from the atmosphere into an evacuated passage, introducing the member into a nozzle located in the lower portion of a crucible, passing the member continuously through the crucible, increasing the temperature in the crucible to the melting temperature of the member, introducing molten material into the crucible when the melting temperature is attained 7 whereby the molten material accretes on the member to form a member having greater thickness.

6. The method according to claim 5 further comprising the steps of terminating the supply of molten material into the crucible, removing the molten material from the crucible by accretion on the moving member, decreasing the temperature in the crucible and terminating the supply of the member into the crucible.

7. In a method for accreting molten copper on a member the steps which consist in cleaning the surface of the member, passing the member from the atmosphere into an evacuated passage, introducing the member into a nozzle located in the lower portion of a crucible, increasing the temperature in the crucible, passing the member continuously through the crucible, introducing molten copper into the crucible when the melting temperature of the member is attained whereby the molten copper accretes on the member to form a member having greater thickness.

8. In a method for accreting molten material on a member the steps which consist in cleaning the surface of the member, passing the member from the atmosphere into an evacuated passage, introducing the member into a nozzle located in the lower portion of a. crucible, passing the member continuously upwardly in a substantially vertical direction through the crucible at a speed of approximately 2 ft./minute, increasing the speed of the continuously moving member when the melting temperature of the member is attained in the crucible, introducing molten material into the crucible when the melting temperature is attained whereby the molten material accretes on the member to form a member having greater thickness.

9. In a method for accreting molten copper on a copper member the steps which consist in cleaning the surface of the copper member, passing the copper member from the atmosphere into an evacuated passage, introducing the copper member into a nozzle located in the lower portion of a crucible, increasing the temperature in the crucible to approximately 800 C., passing the copper member continuously through the crucible at a speed of approximately 2 ft./minute, increasing the temperature in the crucible, increasing the speed of the continuously moving copper member when the melting temperature of the copper member is attained in the crucible, introducing molten copper into the crucible when the melting temperature is attained whereby the molten copper accretes on the member to form a member having greater thickness.

10. The method according to claim 9 further comprising the steps of terminating the supply of molten copper into the crucible, removing the molten copper from the crucible by accretion on the moving member, decreasing the temperature in the crucible and terminating the supply of the copper member into the crucible.

11. In an apparatus for accreting molten material on a 55 moving member the combination of a crucible, nozzle means located in the lower portion of the crucible adapted to introduce the member into the crucible, means defining an evacuated passage associated with the nozzle means, seal means for maintaining the condition of the evacuated passage, means for passing the member through the nozzle into the crucible at a first speed, means for increasing the temperature in the crucible, means for increasing the speed of the member when the melting temperature of the member is reached in the crucible, and means for introducing molten material into the crucible when the melting temperature is reached whereby the molten material accretes on the moving member to form a member having greater thickness.

12. In an apparatus for accreting molten material on a moving member the combination of a crucible, nozzle means associated with the lower portion of the crucible adapted to introduce the member into the crucible, means defining an evacuated passage associated with the nozzle means, seal means for maintaining the condition of the evacuated passage, means for passing the member through the nozzle into the crucible at a first speed, means for increasing the temperature in the crucible, means for increasing the speed of the member when the melting temperature of the member is attained in the crucible, and means for introducing molten material into the crucible when the melting temperature is reached whereby the molten material accretes on the moving member forming a member having greater thickness.

13. In an apparatus for accreting molten copper on a moving copper member the combination of a crucible, nozzle means located in the lower portion of crucible adapted to introduce the moving member into the crucible, means defining an evacuated passage associated with the nozzle means, seal means for maintaining the condition of the evacuated passage, means for passing the member through the nozzle from the evacuated passage into the crucible at a first speed when the temperature of approximately 800 C. is reached, means for increasing the temperature in the crucible, means for increasing the speed of the member when the melting temperature of copper is reached in the crucible, and means for introducing molten copper into the crucible when the melting temperature is reached whereby the molten copper accretes on the moving copper member to form a member having greater thickness and being substantially homogeneous in character.

References Cited in the tile of this patent UNITED STATES PATENTS 2,092,284 McCarroll et al Sept. 7, 1937 2,543,936 Reynolds Nov. 6, 1951 2,959,829 Brennan Nov. 15, 1960 FOREIGN PATENTS 706,113 Great Britain Mar. 24, 1954

Claims

5. IN A METHOD FOR ACCRETING MOLTEN MATERIAL ON A MEMBER THE STEPS WHICH CONSIST IN CLEANING THE SURFACE OFD THE MEMBER, PASSING THE MEMBER FROM THE ATMOSPHEREE INTO AN EVACUATED PASSAGE, INTRODUCING THE MEMBER INTO A NOZZLE LOCATED IN THE LOWER PORTION OF A CRUCIBLE, PASSINGTHE MEMBER CONTINUOUSLY THROUGH THE CRUCIBLE, INCREASING THE TEMPERATURE IN THE CRUCIBLE TO THE MELTING TEMPERATURE OF THE MEMBER, INTRODUCING MOLTEN MATERIAL INTO THE CRUCIBLE WHEN THE MELTING TEMPERATURE IS ATTAINED FIG -01 WHEREBY THE MOLTEN MATERIAL ACCRETES ON THE MEMBER TO FORM A MEMBER HAVING GREATER THICKNESS