Patent Publication Number: US-8118643-B2

Title: Method of descaling metal wire rod and apparatus therefor

Description:
TECHNICAL FIELD 
     This invention relates to a method of removing scales from metal wires for removing scales generated in a process of stretching the metal wires such as steel wires, by using a high-pressure fluid mixed with an abrasive scavenging agent and to an apparatus therefor. 
     BACKGROUND ART 
     For example, in a process of hot-stretching steel wires by heating at a high temperature, a mill scale (black film) or a scale (oxide film) including the mill scale is generated on the surfaces. In order to remove these scales, a method now is employed according to which the scales are trimmed off by using a ring-shaped peeling blade before entering a wire-stretching die. 
     At present, further, a method of treatment with acid is frequently used in which metal wires in a pool of acid is dipped to dissolve and remove the scales.
     Patent document 1: JP-A-2001-32042   

     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     Problems to be Solved by the Invention 
     In the conventional mechanical peeling process, however, the peeling blade is worn out in a certain period of time and must be replaced. Here, since the blade has a ring-like shape, it becomes necessary to once cut the wire to replace the blade, and thereafter, deposit the wire. In this case, however, the wire loses consistency of quality, for instance having unstable electric resistance at the deposited portion. Above all, laborious work is required, further, causing a large time loss and pushing up the cost. Further, the scales often remain without being completely peeled off, causing stains to be burnt in the wire-stretching die. In the conventional treatment with acid, further, cumbersome work is required for treating the acid after use, which pushes up the cost and undesirably affects the environment. 
     This invention has been achieved in view of the above background art, and has an object of providing a method of removing scales from metal wires capable of reliably removing oxide films on the surfaces of the stretched metal wires and an apparatus therefor, relying upon a simple method and apparatus. 
     Means for Solving the Problems 
     This invention is concerned with a method of removing scales formed on the surfaces of wires during a process of stretching metal wires by injecting a slurry of a liquid in which an abrasive scavenging agent is mixed together with a high-pressure fluid toward the surfaces of the metal wires from mixing nozzles that inject the high-pressure liquid, and bombarding the abrasive scavenging agent in the high-pressure injected liquid upon the scales on the surfaces of the metal wires to remove the scales. 
     As the abrasive scavenging agent, spherical fine particles having particle sizes of about 40 μm to about 800 μm are used. Spherical zircon beads, spherical zirconia beads or spherical stainless steel beads can be used as the spherical particles of the abrasive scavenging agent. 
     The liquid with which the abrasive scavenging agent is mixed is a liquid obtained by mixing a water-soluble cutting oil with water, and the high-pressure water mixed with the abrasive scavenging agent in the liquid is injected toward the surfaces of the metal wires. 
     The invention is, further, concerned with a metal wire scale removing apparatus for wire undergoing a process of stretching, to remove scales formed on the surfaces of the metal wires, comprising a liquid container tank through which metal wires pass, mixing nozzles disposed to allow the metal wirings to pass through the liquid container tank for injecting a high-pressure liquid toward the metal wires, a high-pressure pump for feeding the high-pressure liquid to the mixing nozzles, and a slurry feeder for feeding a slurry containing an abrasive scavenging agent mixed with a liquid to the mixing nozzles; wherein the mixing nozzles inject the slurry of the abrasive scavenging agent together with the high-pressure liquid so that the abrasive scavenging agent impinges upon the scales on the surfaces of the metal wires to remove the scales. 
     Provision is made of a separator for recovering the liquid with which the abrasive scavenging agent is mixed, and for separating the liquid and the abrasive scavenging agent from each other, the abrasive scavenging agent in slurry form being fed from the separator to the mixing nozzles, and provision is further made of a separating/recovering device such as a filter device for recovering the liquid from the separator and further separating the abrasive scavenging agent. The slurry feeder is used jointly with the separator. 
     The separating/recovering device includes a scale recovering device using magnets or the like for separating and recovering the removed scales in the liquid with which the abrasive scavenging agent is mixed. Further, the separating/recovering device includes a filter or a sedimentation tank for separating the abrasive scavenging agent in the liquid with which the abrasive scavenging agent is mixed, and feeds the liquid from which the abrasive scavenging agent and the scales have been removed to the high-pressure pump. 
     Effects of the Invention 
     By using the method of removing scales from the metal wires and the apparatus therefor of the invention, there is provided an apparatus for removing scales formed on the surfaces of the metal wires, which is inexpensive and efficient. By using the method of removing scales from the metal wires and the apparatus therefor of the invention, further, there is no need of conducting a very laborious step of replacing the blades that had to be done at regular intervals in the course of removing the scales, contributing to strikingly improving the production efficiency. By using the abrasive scavenging agent including particles of a spherical shape, further, the wires are not scratched as when wire brushes are used, and wires having stable quality can be supplied. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view schematically illustrating the whole constitution of an apparatus for removing scales from metal wires according to an embodiment of the invention. 
         FIG. 2  is a vertical sectional view of the apparatus for removing scales from metal wires according to the embodiment. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           10  metal wire 
           12  liquid container tank 
           12   a  upper container portion 
           12   b  lower container portion 
           14  mixing nozzles 
           16  high-pressure pump 
           18  high-pressure hoses 
           20  cyclone separators 
           22  hoses 
           24  feed hoses 
           26  delivery hoses 
           30  magnets 
           32 ,  34  underwater pumps 
           40  wheel-type filter 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the invention will now be described with reference to  FIGS. 1 and 2 . An apparatus for removing scales from metal wires of this embodiment is placed in a process of stretching a metal wires  10 , to remove scales such as oxide films formed on the surfaces of the metal wires  10  such as steel wires. The apparatus for removing scales has a liquid container tank  12  in which the metal wires  10  pass. In the liquid container tank  12  are provided mixing nozzles  14  for injecting a high-pressure liquid to the metal wires  10 , and a high-pressure pump  16  for feeding the high-pressure liquid to the mixing nozzles  14 . The high-pressure pump  16  generates a high-pressure fluid of, for example, about 5 to 30 MPa. To the high-pressure pump  16  are connected a plurality of high-pressure hoses  18 , for example, three to four, which are connected to the mixing nozzles  14  arranged at upper positions in the liquid container tank  12 . The mixing nozzles  14  accelerate the velocity of flow to a speed close to the speed of sound. 
     The mixing nozzles  14  are positioned at upper portions of the liquid container tank  12 , and cyclone separators  20  are positioned over them. The cyclone separators  20  work as an abrasive scavenging agent separating/recovering device and, further, work as a slurry feeder. That is, the cyclone separator  20  has a funnel-like container portion  20   a  which also works as a slurry feeder for separating the abrasive scavenging agent from the water with which the abrasive scavenging agent is mixed, for collecting the abrasive scavenging agent, for forming a slurry in which the abrasive scavenging agent is mixed with water, and for feeding the slurry to the mixing nozzle  14 . A hole at the lower end of the container portion  20   a  is connected to the mixing nozzle  14  via the hose  22 . To the container portion  20   a  is also connected a feed hose  24  for feeding the liquid in the lower layer of the liquid container tank  12 . A delivery hose  26  is connected to an upper part of the container portion  20   a  of each cyclone separator  20  to deliver the liquid component separated by the cyclone separator  20  to a wheel-type filter  40  that will be described later. The feed hoses  24  are collected into one feed hose  24   a  and the delivery hoses  26  are collected into one delivery hose  26   a  for recovering the liquid component, at positions separated by predetermined distances from the cyclone separators  20 , respectively. 
     The liquid container tank  12  is constituted by an upper container portion  12   a  and a lower container portion  12   b . A pair of insertion holes  13  is liquid-tightly formed in the upper container portion  12   a  permitting the metal wire  10  to pass through, and guide rollers  28  are provided on both sides of the insertion holes  13 . A tilted surface portion  15  tilted downward in a pyramidal shape is formed under the positions where the metal wire  10  passes through, a through hole is formed in the lower end of the tilted surface portion  15 , and the liquid flows down through the through hole. Magnets  30  are arranged surrounding the through hole so as to adsorb and remove magnetic components. The lower container tank  12   b  is positioned under the magnets  30 . An underwater pump  32  is disposed on the bottom surface of the lower container portion  12   b , and the feed hoses  24  are connected thereto to feed the liquid to the cyclone separators  20 . An underwater pump  34  is provided at a central portion, too, in the lower container portion  12   b  to suck the liquid into the lower container portion  12   b  and to circulate it into the lower layer through a hose  36 . 
     The mixing nozzles  14  are arranged at four places at intervals of 90° with respect to the metal wire  10  within the upper container portion  12   a , and displaced from each other by a given distance in a pass-through direction of the metal wirings. The angles of the mixing nozzles  14  with respect to the metal wire  10  can be suitably set depending upon the feeding speed of the metal wire  10 , and are suitably adjusted in a range of from 30° to 150°. When the mixing nozzles  14  are arranged at three places, they may be arranged at the intervals of 120°, and the number of installed mixing nozzles and the intervals therebetween can be suitably set. If the nozzle diameter is φ=D, a distance from the metal wire  10  to the mixing nozzle  14  is most effectively 20 D to 200 D. If injection is made at an angle counter to a direction in which the metal wire  10  travels, the area of contact increases and the relative speed increases to improve efficiency. In this way, the nozzle angle is suitably adjusted depending upon the speed of drawing the metal wire  10 . 
     The wheel-type filter  40  provided at the outlet of the delivery hose  26  is positioned over the sedimentation tank  42 , and recovers zircon beads which are the abrasive scavenging agent in the liquid. A receiving portion  38  is provided, and the abrasive scavenging agent is returned back to the liquid container tank  12  through the hose  39 . Further, the zircon beads are settled in the sedimentation tank  42 , and the liquid in the surface layer portion in the sedimentation tank  42  is circulated into the high-pressure pump  16  through the hose  44 . 
     In this embodiment, the liquid that is used is produced by mixing a water-soluble cutting oil in water at a ratio of 1:50. The abrasive scavenging agent mixed into the water comprises spherical zircon (ZrSiO 4 ) particles of nearly completely spherical shape having a particle size of about 40 μm to about 800 μm and, preferably, 100 μm to about 400 μm. The spherical zircon beads that are used have a specific gravity of 3.8 and a Mohs hardness of about 7. The spherical zircon beads have a large specific gravity and readily settle. In order to disperse the abrasive scavenging agent of spherical zircon beads in water, therefore, the water with which the abrasive scavenging agent is mixed is circulated by using the underwater pump  34 . Or, the water may be directly stirred by providing any other stirrer device in the water tank. 
     As the abrasive scavenging agent, there can be also used other zirconia (zirconium oxide: ZrO 2 ) beads having a high strength and a high toughness in addition to the zircon beads of spherical zircon. For example, there can be used yttria-stabilized zirconia (ZrO 2 Y 2 O 3 ). The yttria-stabilized zirconia has a high durability and a stable shape. Moreover, spherical stainless steel beads can often be used. The above beads can be suitably used depending upon the cases. 
     Next, described below is the operation of the apparatus for removing scales of the embodiment. Water with which the abrasive scavenging agent is mixed is delivered from the underwater pump  32  and fed into the cyclone separators  20  at four places through one feed hose  24   a  and then through the individual feed hoses  24 . In the cyclone separators  20 , water containing the abrasive scavenging agent whirls like a cyclone in the container portion  20   a , and the abrasive scavenging agent collects along the funnel-like inner peripheral surface of the container portion  20   a . The abrasive scavenging agent having a large specific weight collects on the inner peripheral surface of the container portion  20   a , and is expelled in slurry form along the tilted surface through the small hole in the lower end. The slurry of water and abrasive scavenging agent from the container portion  20   a  is delivered to the mixing nozzles  14  through the hoses  22 . On the other hand, delivery hoses  26  are connected to the upper central portions of the conical container portions  20   a  to suck the water that remains after the abrasive scavenging agent is forced to the inner surface of the conical container portions  20   a , and to send the water to the wheel-type filter  40 . 
     Water of a high pressure is fed from the high-pressure pump  16  to the mixing nozzles  14 , and is injected from the nozzle tips at velocity of flow close to the speed of sound. Here, in the mixing nozzles  14 , the slurry of the abrasive scavenging agent fed from the cyclone separators  20  is so mixed as to be sucked by water of high pressure, and a high-pressure injection stream containing the abrasive scavenging agent is injected from the nozzle tips. 
     The injection stream containing the abrasive scavenging agent injected at a high speed bombards the scales on the surface of the metal wire  10  and grinds the scales with the abrasive scavenging agent. Here, the abrasive scavenging agent comprising zircon beads of a spherical shape works to finish the metal wire  10  such as steel wire to have a flawless surface without scratching. In particular, the abrasive scavenging agent of spherical zircon beads which is a non-metal does not cause foreign metals to deposit on the metal wire  10  and suppresses the probability of corrosion of the metal wire  10 . 
     In the upper container portion  12   a  of the liquid container tank  12 , the abrasive scavenging agent falls down together with scales and water after having bombarded the surface of the metal wire  10 , i.e., falls down along the tilted surface portion  15  of the upper container portion  12   a  into the lower container portion  12   b . The magnetic components are attracted and removed by magnets  30  provided surrounding the through hole at the lower end of the upper container portion  12   a . In the lower container portion  12   b , the mixture of water and abrasive scavenging agent is sucked by the underwater pump  32 , delivered to the cyclone separators  20  where it is separated into water and the slurry of abrasive scavenging agent due to the above described function. 
     Water sucked from the cyclone separators  20  is removed of about 90% of the abrasive scavenging agent. The abrasive scavenging agent is further removed by the wheel-type separator  40 . However, water that is sent to the high-pressure pump  16  must be almost free of foreign matter. Therefore, the remaining water is fed into the sedimentation tank  42  where the abrasive scavenging agent is removed by sedimentation, and so water only is fed to the high-pressure pump  16  through the hose  44 . 
     According to the apparatus for removing scales from the metal wires of this embodiment, high-pressure treating water from the high-pressure pump  1  is injected from the mixing nozzles  14  together with the spherical abrasive scavenging agent, bombards the surface of the metal wire  10  at high speeds, and instantaneously removes the scales from the surface without adversely affecting the metal wire  10 . 
     Here, in addition to a tank that is divided into the upper container portion  12   a  and the lower container portion  12   b , the liquid container tank  12  of the apparatus for removing scales of the metal wire of the invention may be the one that has only one container portion. Further, a liquid container tank  12  may be provided for each mixing nozzle  14 .