US 3758913 A
An apparatus for removing coolant from a moving metal surface which comprises a housing defining a chamber, having an opening therein facing the moving metal surface; a flexible contacting member attached to at least the leading edge of the housing opening, and preferably to both the leading and trailing edges of the housing opening, in contact with the metal surface; and suction means connected to the housing to evacuate the chamber. Such apparatus can be used in a method of removing coolant from metal surfaces by contacting the surface with a flexible member and passing the surface through a suction zone.
Description (OCR text may contain errors)
United States Patent 1 [111 3,758,913 Elliott et al. [4 1 Sept. 18, 1973 APPARATUS FOR REMOVAL OF COOLANT 3,531,059 9/1970 Walker 15/88 X FROM METAL SURFACES 2,296,801 9/1942 Thomas l5/88 X 2,277,444 3/1942 McPhee 15/394 X Inventors: Herbert Elliott; Frank A. Slmons,
both of Midland, Mich.
The Dow Chemical Company, Midland, Mich.
Filed: Nov. 17, 1971 Appl. No.: 199,418
Related US. Application Data Division of Ser. No. 59,075, July 29, 1970, Pat. No. 3,653,425.
References Cited UNITED STATES PATENTS 10/1962 Doyle 151306 A 7/1968 Herbert 15/308 X Primary Examiner-John Petrakes Assistant Examiner-C. K. Moore Attorney-Griswold & Burdick  ABSTRACT An apparatus for removing coolant from a moving metal surface which comprises a housing defining a chamber, having an opening therein facing the moving metal surface; a flexible contacting member attached to at least the leading edge of the housing opening, and preferably to both the leading and trailing edges of the housing opening, in contact with the metal surface; and suction means connected to the housing to evacuate the chamber. Such apparatus can be used in a method of removing coolant from metal surfaces by contacting the surface with a flexible member and passing the surface through a suction zone.
3 Claims, 3 Drawing Figures Vac uum PATENTEDSEPI 8 ms Ebb Us;
APPARATUS FOR REMOVAL OF COOLANT FROM METAL SURFACES CROSS REFERENCE TO RELATED APPLICATION This application is a Division of application Ser. No. 59,075, filed July 29, I970, now U.S. Pat. No. 3,653,425.
BACKGROUND OF THE INVENTION There are many instances in metal processing and fabrication where a coolant, e.g., water is applied to and then subsequently removed from the metal surface. For example, in the continuous direct chill casting of metal billets, coolant is applied to the solid billet surface as it emerges from a short, open ended mold. Zeigler (U.S. Pat. No. 2,708,297 and U.S. Pat. No. 2,705,353) has shown that in casting high strength aluminum alloys of large cross-section, it is advantageous to remove the coolant from the cast billet just below the mold. Also in hot rolling metal sheet or strip, coolant is applied to the metal being rolled and then removed as the metal leaves the rolling mill.
Conventionally the coolant is removed by either mechanical wipers or by air jets. Mechanical wiping employs, for example, a piece of flexible rubber fitted tightly around the metal surface. The rubber wipes the water off as the surface passes through. Alternatively the coolant is blown from the metal surface by gas jets assisted in some cases by baffles or deflectors to direct the gas streams and to assist in collecting the removed coolant.
These systems suffer from some disadvantages. The mechanical wipers are unreliable in removing coolant from rough metal surfaces and are difficult to maintain. The flexible material tends to tear and wear away causing leaks and non-uniform removal of coolant. The air jet systems in many instances require precise engineering and adjustment to obtain complete, proper removal of coolant. They also tend to blow large amounts of coolant into the surrounding atmosphere causing corrosion on equipment and discomfort to operators.
An object of the present invention is to provide a relatively simple apparatus and method for effective, uniform coolant removal from moving metal surfaces even in the presence of considerable surfaceroughness.
SUMMARY OF THE INVENTION The apparatus of the present invention comprises a housing, which defines a chamber, having an opening therein; a flexible contacting member attached to the leading edge of the housing opening; and suction means connected to the housing for evacuating the chamber. Optionally a second flexible contacting member is attached to the trailing edge of the housing opening.
When this apparatus is employed to remove coolant from a moving metal surface, the housing is placed adjacent to the metal surface. It is positioned such that the opening is facing, i.e. directed toward, the moving metal surface and the contacting member is in contact with that surface. The housing and the suction means define a suction or vacuum zone surrounding or adjacent to the metal surface.
The method of the present invention comprises contacting the metal surface with a flexible member, and then passing the metal surface through an adjacent suction zone to remove the coolant therefrom.
The term leading edge, used herein, refers to that edge of the housing opening which the metal surface passes first.
The term trailing edge, as used herein, refers to that edge of the housing opening which the metal surface passes last.
The present apparatus and method are further understood and illustrated by the following figures.
FIG. 1 is the top view of one embodiment of the apparatus of the present invention.
FIG. 2 is a cross-section of FIG. 1 taken along line 2--2.
FIG. 3 is a diagram of the continuous casting operation employing one embodiment of the present invention.
SPECIFIC EMBODIMENTS The preferred apparatus of the present invention will be described in a configuration adapted for the removal of cooling water from the surface of a cylindrical ingot as it is being cast in a vertical sense. Obvious adaptations of the principle make it equally useful for ingots of other shapes than cylindrical, and cast horizontally or at a slant rather than vertically, or even for removing the coolant from a strip of metal as it leaves a rolling mill or strip of metal as it leaves a heat treating and quenching line.
The preferred apparatus comprises a housing defining a chamber surrounding the ingot with an opening facing the billet surface. Suction is applied to the housing chamber, causing a stream of air to flow into the opening. This air stream removes the cooling water from the billet surface and carries it into the chamber, from which it is removed and disposed of.
For effective water removal with a minimum of air flow, the device is fitted with a flexible member attached to the leading edge of the housing opening and extending toward the metal surface to make contact therewith to act as a sealing means. Optionally, a similar flexible member can be attached to the trailing edge of the housing opening also extending toward the metal surface to make contact therewith.
Referring to FIGS. 1 and 2, a housing, generally noted as l, is shown. Such housing comprises top ring 2, bottom ring 3 and a perpendicular member 4, which connects the top and bottom rings around their outer peripheries. A flexible contacting member, e.g., brush 5, is attached to the top ring by means of hold down dogs 6. A second flexible contacting member, e.g. brush 5' is attached to the bottom ring by a hold down ring 7 and bolts 8. The housing 1 is connected to suetion means (not shown), e.g., vacuum pump, by means of conduit 9. The top ring is provided with a lip 10 and channel 11.
FIG. 3 is a drawing of a continuous casting operation Molten metal is continuously cast into a billet 20 through a short, water cooled, open ended mold 21. Water spray rings 22 cool the mold and the casting. The water removal apparatus is positioned below the spray rings. The housing 1 is suspended independently of the billet, e.g., by hanging it on a chain from the mold table, so that it is concentric with the metal billet. The relationship of the billet diameter to the inside diameter of the brushes 5 and 5 is such that the brushes make contact with the billet surface, maintaining the housing in a centered position relative to the billet axis.
In the practice of this embodiment, molten metal is cast into mold 21 where it begins to solidify. The partly solidified billet passes through the mold 21 and the casting surface is further cooled by water spray from rings 22. The wetted surface then contacts the upper brush 5 and passes into suction zone S. As air passes through this suction zone, it literally strips the water from the billet surface.
Preferably the contact of the billet surface with brush 5 is sufficiently tight to wipe some of the water from the surface. The lip on the top ring will then cause the water to pool up over the brush 5. This seals the upper edge of the housing opening promoting effective water removal with lower suction power.
The housing of the present apparatus is any device which defines a chamber, having an opening therein, which faces the moving billet surface, for example, a pipe or hollow ring with a slot on the inner circumference. However, the housing may be of any shape convenient for fabricatiOn or use, such as by using upper and lower plates having the centers cut out to allow passage of the billet, and spaced apart by a vertical wall. In any case, the opening directed toward the billet surface need only be wide enough to permit passage of an air stream from the surrounding area, over the billet surface, and into the chamber.
The flexible contacting member can be made of any flexible, resilient material capable of withstanding the metal surface temperatures involved, and of such nature as to offer resistance to the flow of air and water into the chamber. Examples include sheet rubber or rubber-like materials. A particularly useful configuration is a brush, having bristles made of natural or synthetic fibers, metal, or other suitable material.
To minimize the amount of air flow required for effective removal of water by the device, it is important that the contacting member attached to the leading edge of the housing opening provide substantial resistance to the flow of air into the suction chamber from the space above the chamber. For this purpose, if a sheet of rubber or rubber-like material is used as the contacting member, it should fit fairly snugly around the billet surface. It is not necessary that it fit so snugly as to effectively remove all the water by a mechanical wiping action. Considerable leakage through this leading member is permissible, since the coolant that leaks through will be picked up by the air stream in the suction zone; but the presence of a wide gap between the contacting member and the billet surface will greatly increase the air flow required for complete water removal. If a. brush is used as the contacting member, the density of packing of the bristles must be sufficient so that the brush will offer adequate resistance to air flow. For example, in removing the cooling water from the surface of a 12 inches diameter billet, it was found that a commercial strip brush having uncrimped Tampicotype fiber bristles, trim length 2 inches, when formed into a circular shape with the bristle tips initially set to an 1 l 5% inch inside diameter, gave effective wiping action with a minimum of air flow.
Optionally, a flexible contacting member attached to the trailing edge of the housing opening can be used. If the trailing edge of the housing is only slightly larger in inside diameter than the diameter of the billet, e.g. an annular space not much greater than one-eighth inch between the billet and the suction chamber, water removal will be complete even at quite small air flow rates without use of a second flexible contacting member. However, the use of a brush attached to the trailing edge as well as the leading edge of the housing opening makes it possible to keep all rigid parts of the device well back away from the billet surface, which allows the device to function in spite of very severe irregularity of the casting surface.
The flexible contacting member attached to the leading edge of the housing opening should preferably, although not necessarily, remove some water from the billet surface. It is further preferred to provide a guttering or channeling system, e.g. a lip on the top of the housing placed behind the contacting member (see FIG. 1 and 2). As the water is wiped" from the surface, it thus pools up over the contacting member, further sealing the upper annulus from the throughpassage of air. By thus sealing the upper annulus, the amount of suction necessary to completely remove the coolant is substantially reduced.
Another function of the flexible contacting member is to maintain the device in a centered position in relation to the billet.
The suction means is any means by which the air pressure is reduced in the suction chamber so as to cause air to flow in through the opening facing the billet surface, e.g. a vacuum pump.
EXAMPLE 1 A 12 inches diameter billet of A2318 alloy (3% Al, l% Zn, 0.4% Mn, bal-Mg) was cast at a melt temperature of 1,300F in a copper mold, [2 inches long, starting with a slow casting speed and increasing casting speed by steps to 5.2 inches per minute. Water was applied to the mold through two water rings (7 gallons per minute and 8 gallons per minute was adequate). The mold cooling water then flowing onto the emerging billet. The upper edge of the housing of the present apparatus was located at a level three-fourths inch below the mold exit.
The housing was made by an upper plate and a lower plate spaced 1 inch apart by a vertical wall around the outer perimeter of the plates having a diameter of 18 inches. Upper and lower plates had central holes 14 inches in diameter for passage of the 12 inches diameter billet. The suction chamber deflned thereby was connected by a 3 inches ,diameter hose to a vacuum vessel of 10 gallon capacity, fitted with a drain and maintained at a pressure of 20-22 cm H 0 below atmospheric pressure. This was accomplished by using a 1 HP low pressure turbine-type blower as a vacuum generator. Tampico fiber strip brushes, 2 inches trim length, uncrimped bristles were formed to a circular shape with bristles pointing inward. Bristle tips were intially set to an inside diameter of l] a inches diameter. One such brush was attached to the upper and one to the lower plate of the housing.
in operation, water removal was complete throughout the cast, the billet surface being dry. as it emerged through the lower brush. Some water was shed by the upper brush, resulting in a pool of water helping to seal the upper annulus. The water that was shed was led off in such a way as not to fall back on the casting. Most of the cooling water that was applied to the mold and to the emerging cast billet passed through the upper brush, but was removed and disposed of by the vacuum system.
EXAMPLE 2 A 6 1% inch diameter billet of AM30 alloy (3% Al, 0.35% Zn, 0.4% Mn, bal-Mg) was cast at a melt temperature of 1,280F in a copper mold 9 inches long starting with a slow casting speed and increasing the speed by steps to 20.5 inches per minute. Water was applied to the mold through two water rings, each at a flow rate of 5 gallons per minute, and to the emerging billet through two rings carrying a combined flow of 8 gallons per minute. The upper edge of the housing of the present apparatus was located at a level 3 A inches below the mold exit. The housing was made by an upper plate and a lower plate spaced 1 inch apart by a vertical wall 18" in diameter. Upper and lower plates had central holes 8 56 inch in diameter for passage of the 6 k inch diameter billet. The suction chamber was connected by a 3 inches diameter hose to a vacuum vessel of gallons capacity fitted with a drain and partially evacuated by using a 1 HP turbine type low pressure blower as a vacuum generator.
Tampico fiber strip brushes, 2 inches trim length, uncrimped bristles were formed to a circular shape with bristles pointed inward. Bristle tips were initially set to an inside diameter of 5 V4 inch. One such brush was attached to the upper and one to the lower plate of the housing defining the suction chamber.
With this design, considerable water tended to be shed by the upper brush. To avoid the need for a guttering and lead-off system to dispose of the water that was shed, the upper brush was intentionally remounted in such a way as to allow water to leak under the backing of the brush into the suction chamber sufficiently so that all of the cooling water passed into the suction chamber. The 1 HP blower that was used still had 6 ample capacity to accomplish perfect wiping action, and in operation the billet surface was dry at all casting speeds as it emerged through the lower brush.
What is claimed is:
1. An apparatus for removing liquid coolant from a moving, continuously cast, solid, cylindrical metal billet, which includes the combination of:
a housing which is defined by top ring member with a central opening therein, a bottom ring member with a central opening therein, and a peripheral wall member which joins the top ring member to the bottom ring member;
the housing being positioned around the moving billet, such that the opening in the top ring defines a leading edge which faces the moving billet, and the opening in the bottom ring defines a trailing edge which faces the moving billet;
a first flexible member which is mounted on the top ring member adjacent to the leading edge opening, which surrounds the cylindrical billet, and which is in wiping contact with the outer surface of the billet, to enable removing liquid coolant from the moving billet surface; suction means in communication with the bottom ring member at a point below the first flexible member, for evacuating the ring member to thereby remove additional liquid coolant from the moving billet surface.
2. The apparatus of claim 1 in which a second flexible member is mounted on the bottom ring member adjacent to the trailing edge opening and in wiping contact with the surface of the moving cylindrical billet.
3. The apparatus of claim 2 in which the first and second flexible members are brushes. t i i i