JP5618607B2 - Capstan block for wire drawing machine - Google Patents

Description

  The present invention relates to a capstan block for a wire drawing machine used in a wire drawing machine for metal wires.

  In a metal wire drawing machine, a wire drawn by a plurality of dies arranged in a plurality of stages is wound around an outer peripheral surface of a rotationally driven capstan block and pulled out. A capstan block arranged between a plurality of dies draws a wire rod from a front die and feeds the drawn wire rod to a rear die. These capstan blocks have a hollow cylindrical shape and are conventionally formed of cast iron or cast steel.

  The capstan block is faster than the speed of the wire drawn from the front-side die in order to give a large front tension or rear tension to the wire to be drawn and reduce the processing load on the die. It is rotationally driven at a peripheral speed slower than the speed of the wire fed into the side die. For this reason, slip occurs between the outer peripheral surface of the capstan block and the wire to be wound, and wear and seizure are likely to occur.

  As a means for preventing such wear and seizure of the outer peripheral surface of the capstan block, a method of applying hard chrome plating (for example, see Patent Document 1) or a method of forming a hard ceramic film (for example, Patent Document 2). For example, it is proposed to form a hard coating on the outer peripheral surface. In Patent Document 2, a vacuum vapor deposition method, an ion plating method, a sputtering method and the like are cited as a method for forming a hard ceramic film.

  Also, the wire drawn from the die becomes considerably hot due to heat generated by the processing, and a large heat load is applied to the capstan block from the wire wound around the outer peripheral surface. For this reason, the hollow capstan block is cooled from the inside by injecting cooling water or the like onto the inner peripheral surface (see, for example, Patent Document 3).

  Furthermore, since a high local surface pressure is applied to the outer peripheral surface of the capstan block from a wire wound with a large tension, a high surface strength is required so that no dent deformation occurs on the surface. The local surface pressure becomes higher as the wire to be drawn is thinner and higher in strength, such as a steel cord that reinforces an automobile tire.

Japanese Patent Laid-Open No. 7-164039 JP 2002-28715 A JP-A-8-309427

  The conventional capstan block for wire drawing machine made of cast iron or cast steel described above can secure wear resistance and seizure resistance by forming a hard film on the outer peripheral surface, but it is heavy. There is a problem that handling property when removing for lot change, maintenance, etc. is poor, and the load on the motor to be rotated is increased. Further, since cast iron and cast steel have poor thermal conductivity, there is a problem that cooling efficiency by cooling water from the inside is deteriorated.

  Accordingly, an object of the present invention is to provide a capstan block for a wire drawing machine that has a surface strength equal to or higher than that formed of cast iron or cast steel, and is lightweight and excellent in thermal conductivity.

  In order to solve the above problems, the present invention provides a hollow cylindrical wire drawing machine capstan block in which a metal wire drawn by a wire drawing machine die is wound around an outer peripheral surface and rotated. The base material forming the capstan block is duralumin, the base material on the outer peripheral surface is melted to a predetermined depth using a plasma arc as a heat source, and the base metal on the outer peripheral surface is harder than the base material. The reinforcing particles formed of WC or WC-Co having a large specific gravity are supplied, and the supplied reinforcing particles are settled and deposited on the lower part of the melted portion by gravity, and above the deposition layer on which the reinforcing particles are deposited. In addition, a floating layer is formed by levitating the molten base material, the surface of the floating layer of the base material is smoothed, and a structure in which a hard coating is formed on the surface of the smoothed floating layer by a thermal spraying method is adopted. .

  That is, by using duralumin as the base material for forming the capstan block, it is lightweight and has excellent thermal conductivity, and the base material on the outer peripheral surface is melted to a predetermined depth by a plasma arc. It is formed of cast iron or cast steel by forming a deposited layer in which the reinforcing particles formed of WC or WC-Co having a specific gravity greater than that of the base material are settled and deposited by gravity at the lower part of the base metal melting portion. The surface of the levitation layer with the molten base material levitated on the upper side of the deposition layer, and a hard coating is formed on the surface by thermal spraying. As a result, excellent wear resistance and seizure resistance can be secured. Further, this capstan block has an advantage that it can be used repeatedly by removing the remaining hard film and forming the hard film again by a thermal spraying method when the wear of the hard film becomes thin as it progresses.

  By making the particle size of the reinforcing particles 10 to 300 μm, the reinforcing particles can be stably supplied to the melting part, and preferably 40 to 150 μm so that the particles are more uniformly dispersed in the deposited layer. Can do.

  By setting the thickness of the reinforcing particle deposition layer to 0.3 mm or more, and preferably 0.5 mm or more, the surface layer can be strengthened to a sufficient depth so as not to cause dent deformation on the outer peripheral surface.

  Forming a thermal spray coating on the inner peripheral surface of the hollow cylindrical capstan block using a thermal spray material containing at least one of aluminum, aluminum alloy, zinc, zinc alloy, aluminum-zinc alloy and aluminum-magnesium alloy Thus, corrosion due to cooling water or the like sprayed on the inner peripheral surface is preferentially caused in the sprayed coating, and corrosion of the duralumin base material can be prevented. Thermal spraying can be easily repaired when the thermal spray coating is corroded because there is no need to mask other parts as in wet plating.

  In the capstan block for a wire drawing machine according to the present invention, the base material to be formed is duralumin, the base material on the outer peripheral surface is melted to a predetermined depth by a plasma arc, and the lower part of the melting portion of the base material on the outer peripheral surface is formed. A floating layer in which reinforced particles formed of WC or WC-Co having a specific gravity larger than that of the base material are settled and deposited by gravity, and the molten base material is levitated above the deposited layer on which the strengthened particles are deposited. Since the surface of the floating layer of the base material is smoothed and a hard coating is formed on the smoothed surface of the floating layer by the thermal spraying method, it can be made lightweight and excellent in thermal conductivity. At the same time, a surface strength equal to or higher than that of cast iron or cast steel can be obtained, and excellent wear resistance and seizure resistance can be ensured.

Schematic showing a wire drawing machine employing a capstan block according to the present invention. Fig. 1 is a conceptual vertical sectional view of the capstan block in Fig. 1 The conceptual diagram which shows the PTA method which carried out overlay reinforcement of the outer peripheral surface of the capstan block of FIG. (A) is a photomicrograph showing a surface layer obtained by building up the outer peripheral surface of the capstan block of FIG. 1 by PTA method, and (b) is a photomicrograph in which a part of the deposited layer of (a) is enlarged. A photomicrograph showing a state in which the surface of the floating layer in FIG. 4A is smoothed and a hard film is formed on the surface of the smoothed floating layer. Conceptual diagram showing the wear test method of the example Conceptual diagram showing the thermal conductivity test method of the example The graph which shows the result of the thermal conductivity test of FIG.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 shows a wire drawing machine employing a capstan block 2 according to the present invention. In this wire drawing machine, a capstan block 2 is arranged on the inlet side of each die 1 arranged in a plurality of stages, and a metal wire S drawn by the front die 1 is rotated to each cap that is rotationally driven. The wire rod S is wound around the outer peripheral surface of the stan block 2 and pulled out, and the drawn wire S is sequentially fed to the die 1 on the rear stage side. The peripheral speed of each capstan block 2 that is rotationally driven is set to a speed that is faster than the speed of the wire rod S pulled out from the front die 1 and slower than the speed of the wire rod S fed into the rear die 1. .

  As shown in FIG. 2, the capstan block 2 is formed in a hollow cylindrical shape using duralumin (A7075) as a base material M, and has a flange 2 a that prevents deviation of the wound wire S from the lower end portion. In addition, cooling water is jetted from the nozzle 3 to the inner peripheral surface and cooled from the inside. On the outer peripheral surface including the surface of the flange 2a of the capstan block 2, a deposited layer 5 of reinforcing particles 4 and a floating layer 6 of a base material M on the upper side thereof are formed by a PTA (Plasma Transferred Arc) method described later. A hard coating 7 is formed on the smoothed floating layer 6 by a thermal spraying method. Further, a thermal spray coating 8 made of an aluminum-zinc alloy as a thermal spray material is formed on the inner peripheral surface of the capstan block 2 to prevent the base material M from being corroded by the injected cooling water.

  FIG. 3 is a conceptual diagram showing the PTA method. In this PTA method, a tungsten electrode 13 is arranged in a water-cooled nozzle 12 through which an argon gas 11 flows, and an arc is blown between the tungsten electrode 13 and the water-cooled nozzle 12 to convert the argon gas 11 into plasma, and this plasma plasma arc 14 is irradiated onto the surface of the base material M of A7075 (specific gravity: 2.8), and the reinforcing particles 4 that are harder than the base material M and have a higher specific gravity are applied to the melting portion 15 of the base material M that is melted by the plasma arc 14. The gas is supplied by a carrier gas 16, and the periphery of the plasma arc 14 is shielded by a shield gas 17. In this embodiment, the reinforcing particles 4 are formed of WC (specific gravity: 15.0 to 16.0) having a particle size of 40 to 150 μm. The reinforcing particles 4 may be formed of WC-Co (specific gravity: 13.0 to 15.0) in which WC and Co are combined.

  FIGS. 4A and 4B are photomicrographs showing a cross section of the surface layer of the base material M in a state of being processed by the PTA method. As can be seen from the photograph in FIG. 4 (a), in the base material M, a deposition layer 5 in which the reinforcing particles 4 having a large specific gravity are settled by gravity is formed, and the floating layer 6 is formed by the base material M levitated on the upper side. Is formed. In this photograph, the thickness of the deposition layer 5 of the reinforcing particles 4 is about 1 mm, and the thickness of the floating layer 6 is slightly smaller than the thickness of the deposition layer 5.

  FIG. 4B is an enlarged photograph of a part of the deposited layer 5. As can be seen from this enlarged photograph, the gap between the accumulated reinforcing particles 4 is filled with a part of the molten base material M. Therefore, the base material M of the levitation layer 6 and the base material M below the deposition layer 5 are integrally connected by the base material M filled in the gaps between the reinforcement particles 4 of the deposition layer 5. 5 is prevented, and excellent thermal conductivity of the base material M of A7075 is ensured.

  FIG. 5 shows a state in which the surface of the floating layer 6 of the base material M is smoothed by machining, and a hard coating 7 is formed on the smoothed surface of the floating layer 6 by a thermal spraying method. In this photograph, the floating layer 6 formed by the PTA method is thinned by grinding so as to have a thickness of about 1/4.

  As an example, a deposition layer 5 and a floating layer 6 of WC-6 mass% Co reinforcing particles 4 are formed by a PTA method, and a hard coating 7 is formed by a thermal spraying method on the surface of the floating layer 6 smoothed by machining. A 7075 flat plate sample and a capstan block were prepared. The thickness of the deposited layer 5 was 0.5 mm, and WC-20 mass% Cr-7 mass% Ni (Example 1) and piano wire (Example 2) were used as the thermal spray material for forming the hard coating 7. In the case of Example 1, the construction conditions in the PTA method are changed in the range of voltage 10 to 40 V and current 100 to 200 A, and the thickness of the deposited layer 5 is 1 mm (Example 11), 0.5 mm (Example) 12) and 0.3 mm (Example 13). The thickness of the deposited layer 5 of Example 2 was fixed at 1 mm. Further, as a comparative example, a flat plate sample and a capstan block of A7075 (Comparative Example 1) that were not processed at all and a flat plate sample and a capstan block formed of cast iron (FC25) were prepared. The dimensions of each flat plate sample were 50 mm in length and width and 5 mm in thickness.

  The flat plate samples of Example 11, Example 2, Comparative Example 1 and Comparative Example 2 were subjected to a wear test in accordance with JIS H8615 using a Suga type wear tester. As shown in FIG. 6, the wear test is performed by pressing a wear wheel 25 having abrasive paper 24 on its outer periphery with a predetermined pressing load P against the surface of a flat plate sample 23 fixed to a mounting base 21 with a press plate 22. The mounting base 21 and the flat plate sample 23 are reciprocated at a predetermined stroke S, and the wear ring 25 is rotated by 0.9 ° for each reciprocation of the flat plate sample 23 so that the abrasive paper 24 is brought into contact with the flat sample 23 with a new polishing surface. It touches. As the polishing paper 24, CC320 defined in JIS R6252 was used, the pressing load P was 3 kg, and the stroke S was 30 mm. The weight change of the flat sample 23 is measured with an electronic balance every double stroke, and the number of reciprocations (DS / mg) required for the wear amount of the flat sample 23 calculated from this weight change to be 1 mg. Abrasion resistance was evaluated.

  Table 1 shows the results of the wear test. In Comparative Example 1 that remains A7075 and Comparative Example 2 formed with FC25, the number of reciprocations until 1 mg wear is as low as 8 DS / mg and 12 DS / mg, respectively, and the wear resistance is poor. On the other hand, it can be seen that Example 11 and Example 2 in which the hard coating 7 was formed on the surface greatly increased the number of reciprocations until 1 mg was worn, and had excellent wear resistance. Particularly, in Example 11 in which the thermal spray material of the hard coating 7 is WC-20 mass% Cr-7 mass% Ni, the number of reciprocations is 100 DS / mg, and the wear resistance is remarkably excellent.

  A surface strength test was performed on the flat plate samples of Examples 11 to 13 and Comparative Examples 1 and 2. This surface strength test was performed by a method in which a steel ball having a diameter of 11 mm was slowly pressed onto the surface of a flat plate sample at a speed of 1 mm / min. The pressing load of the steel ball was changed to 3 levels of 1 kN, 3 kN, and 6 kN, and the depth of the pressing marks for each pressing load was measured to evaluate the surface strength.

  Table 1 also shows the results of the surface strength test. In Comparative Example 1 which remains A7075, the depth of the press marks is deeper than Comparative Example 2 formed with FC25, and the surface strength is not sufficient. On the other hand, in Examples 11 and 12 in which the thickness of the deposited layer 5 is 0.5 mm or more, the depth of the press mark is shallower than that of Comparative Example 2 with respect to all levels of pressing load. It can be seen that it has excellent surface strength. Further, Example 13 in which the thickness of the deposited layer 5 is 0.3 mm has a surface strength equivalent to that of Comparative Example 2.

  A thermal conductivity test was conducted using the capstan blocks of Example 13 and Comparative Examples 1 and 2. As shown in FIG. 7, in the thermal conductivity test, a high-temperature wire S pulled out from a die at high speed is wound around a capstan block 2 that is water-cooled from the inside, and the surface temperature of the wound wire S is determined from the start of winding. The thermal conductivity of the capstan block 2 was evaluated at the cooling rate of the wire S by measuring at each winding height position where the winding lengths of the caps were different. The temperature of the wire S at the start of winding was 180 ° C. for all.

  FIG. 8 shows the results of the thermal conductivity test. In Comparative Example 1 in which the capstan block 2 remains A7075, the cooling rate of the wire rod S is the fastest, the winding height is 60 mm, the temperature of the wire rod S is reduced to 40 ° C., and the thermal conductivity is very excellent. In Comparative Example 2 formed with FC25, the cooling rate of the wire rod S is the slowest, and the temperature of the wire rod S is not lowered to 40 ° C. even when the winding height is 200 mm. On the other hand, in Example 13, in which the hardened layer 7 was formed after the deposited layer 5 of the reinforcing particles 4 was formed and the floating layer 6 was smoothed, the winding height was 80 mm and the temperature of the wire S was up to 40 ° C. It is found that the thermal conductivity is slightly inferior to that of Comparative Example 1 which remains as A7075, but the thermal conductivity is greatly improved as compared with Comparative Example 2 formed with FC25.

  In the above-described embodiment, the capstan block has a cylindrical shape with a flange and duralumin is A7075. However, the capstan block is not limited to a cylindrical shape with a flange, and other cylinders such as a taper. It is good also as a shape. Also, duralumin is not limited to A7075.

S Wire material M Base material 1 Die 2 Capstan block 2a 鍔 3 Nozzle 4 Reinforced particles 5 Deposited layer 6 Floating layer 7 Hard coating 8 Thermal spray coating 11 Argon gas 12 Water-cooled nozzle 13 Tungsten electrode 14 Plasma arc 15 Melting part 16 Carrier gas 17 Shield Gas 21 Mounting base 22 Presser plate 23 Flat plate sample 24 Abrasive paper 25 Wear wheel

Claims (4)

  In a capstan block for a hollow cylindrical wire drawing machine that is wound around a peripheral surface of a metal wire that is drawn with a die of a wire drawing machine and is driven to rotate, the base material that forms the capstan block is duralumin, The base material on the outer peripheral surface is melted to a predetermined depth using a plasma arc as a heat source, and the molten portion of the base material on the outer peripheral surface is made of WC or WC-Co that is harder and has a higher specific gravity than the base material. Particles are supplied, and the supplied reinforcing particles are settled and deposited on the lower part of the melting part by gravity, and a floating layer is formed on the upper side of the deposition layer on which the reinforcing particles are deposited, and the molten base material is levitated. A capstan block for a wire drawing machine, characterized in that the surface of the floating layer of the base material is smoothed and a hard coating is formed on the smoothed surface of the floating layer by a thermal spraying method.   The capstan block for a wire drawing machine according to claim 1, wherein the particle size of the reinforcing particles is 10 to 300 μm.   The capstan block for a wire drawing machine according to claim 1 or 2, wherein a thickness of the reinforcing particle deposition layer is 0.3 mm or more.   A thermal spray coating is formed on the inner peripheral surface of the hollow cylindrical capstan block using a thermal spray material containing at least one of aluminum, aluminum alloy, zinc, zinc alloy, aluminum-zinc alloy and aluminum-magnesium alloy. Item 4. A capstan block for a wire drawing machine according to any one of Items 1 to 3.