JP2016222993A - Method for producing high carbon steel wire for spring, and high carbon steel wire for spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for producing a high carbon steel wire for a spring having excellent corrosion resistance, solderability or the like, in which the reduction of die cost can be attained by the elongation of the service life of a wire drawing die, and further, yield can be improved without causing the generation of seizure and galling and the increase of variation in the shape of the spring even if coiling speed is increased.SOLUTION: Provided is a method for producing a high carbon steel wire for a spring comprising: a patenting step where a high carbon steel wire including carbon by 0.5 mass% or more is subjected to patenting treatment; a plating step where the patenting-treated high carbon steel wire is applied with copper alloy plating or copper plating; and a wire drawing step where the plated high carbon steel wire is subjected to wire drawing by a dry or wet die at the total area reduction rate of 75% or more into the fine wires satisfying the wire diameter of 1.0 mmφ or lower, in which the plating step is the one where plating thickness is controlled so as to be 0.1 to 1.6 μm after the wire drawing step.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a high carbon steel wire for a spring and a high carbon steel wire for a spring produced by using the production method.

  Usually, a spring is a tool that rubs a high carbon steel wire for springs manufactured by drawing a high carbon steel wire to a predetermined wire diameter by rubbing a steel wire attached to a spring coiling machine. ) Is used for coiling.

  As such a high carbon steel wire, there are a piano wire and a hard steel wire, which are standardized by JIS, ISO and the like. These high carbon steel wires have high tensile strength, high rigidity (transverse elastic modulus), excellent sag characteristics and fatigue performance, etc. It is widely used as a spring (Patent Document 1).

JP 2000-212795 A

  However, such high-carbon steel wires for springs also have problems such as insufficient corrosion resistance or insufficient solderability depending on applications.

  Moreover, since these high carbon steel wires have high strength (high hardness), there has been a problem that the life of the wire drawing dies is shortened in the wire drawing process than in the case of low carbon steel wires. In particular, when wire drawing is performed to a wire diameter of 1.0 mmφ or less, especially 0.5 mmφ or less, the life of the wire drawing die is remarkably shortened, resulting in a dramatic increase in die cost. The manufacturing cost is higher than the 304 stainless steel wire for spring, which is a very expensive material, and the market price is also expensive.

  In order to obtain a long wire with such a small diameter, in particular, in order to manufacture a precise spring that requires a high carbon steel wire for a spring with a stable wire rod, die wear in the wire drawing process. Since natural diamond dies and artificial diamond dies with a small amount of material must be used, the cost has been further increased.

  In addition, when coiling high-carbon steel wires for springs that have been drawn, when the coiling speed is increased, the friction between the bending die and the steel wire increases, causing seizure and galling. Further, there is a problem that the yield variation in the coiling process is lowered due to an increase in the variation in the shape of the spring.

  Therefore, in view of the above problems, the present invention has better corrosion resistance, solderability, and the like, and prolongs the life of a wire drawing die during wire drawing, particularly 1.0 mmφ or less, particularly 0.5 mmφ or less. The die cost can be reduced by extending the life of the wire drawing dies when drawing high carbon steel wires to obtain thin spring high carbon steel wires. It is an object of the present invention to provide a technique for producing a high-carbon steel wire for a spring that can improve the yield without causing seizure or galling or an increase in variation in the shape of the spring even if the height is increased. In addition, in the manufacturing technology of the high carbon steel wire for springs, it is also an object to improve the appearance of the high carbon steel wire for springs.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by the invention described below, and has completed the present invention.

The invention described in claim 1
A patenting process for patenting a high carbon steel wire containing 0.5% by mass or more of carbon;
A plating process for performing copper alloy plating or copper plating on the patented high carbon steel wire;
The high carbon steel wire that has been plated is drawn with a dry or wet die at a total area reduction of 75% or more, and drawn to a thin diameter of 1.0 mmφ or less. Process,
The high carbon steel wire for springs, wherein the plating step is a plating step in which the plating thickness is controlled so that the plating thickness after the wire drawing step is 0.1 to 1.6 μm. It is a manufacturing method.

The invention described in claim 2
Before the wire drawing step or after the wire drawing step,
The method for producing a high carbon steel wire for a spring according to claim 1, further comprising a film attaching step for attaching an inorganic salt or polymer resin film on the surface of the plating.

The invention according to claim 3
It manufactures using the manufacturing method of the high carbon steel wire for springs of Claim 1 or 2, Comprising: On the surface of the said high carbon steel wire, a 0.1-1.6-micrometer-thick copper alloy layer or copper layer Is a high carbon steel wire for springs.

The invention according to claim 4
4. The high carbon steel wire for spring according to claim 3, wherein the copper alloy layer or the copper layer has a thickness of 0.2 to 1.4 μm.

The invention described in claim 5
5. The high carbon steel for spring according to claim 3, wherein a wire diameter including a thickness of the copper alloy layer or the copper layer and a thickness of the coating is 0.5 mmφ or less. Is a line.

The invention described in claim 6
It is manufactured using the manufacturing method of the high carbon steel wire for springs according to claim 1 or 2.
A copper-zinc alloy layer having a thickness of 0.2 to 1.6 μm is formed on the surface of the high carbon steel wire,
A high carbon steel wire for a spring characterized in that a wire diameter including a thickness of the copper zinc alloy layer and the coating is 0.5 mmφ or less.

  According to the present invention, it has superior corrosion resistance, solderability, etc., prolongs the life of the wire drawing dies at the time of wire drawing, especially for small springs with a small diameter of 1.0 mmφ or less, especially 0.5 mmφ or less. It is possible to reduce the die cost by extending the life of the wire drawing dies when drawing high carbon steel wires in order to obtain carbon steel wires, and even if the coiling speed is increased during coiling, It is possible to provide a technique for producing a high carbon steel wire for a spring that can improve the yield without causing galling or an increase in variation in the shape of the spring.

  In addition, by providing a copper alloy layer or a copper layer, the surface of the high carbon steel wire for springs can be colored gold or copper, so that the appearance of the high carbon steel wire for springs is attached with a drawing lubricant. It can be improved from the black silver color unique to steel wires.

  Hereinafter, the present invention will be described based on embodiments.

  In the high carbon steel wire for springs according to the present embodiment, a copper alloy layer or a copper layer having a thickness of 0.1 to 1.6 μm is formed on the surface of the high carbon steel wire containing 0.5% by mass or more of carbon. It is the high carbon steel wire for springs, and is manufactured based on each process shown below.

(1) Patenting process First, a high carbon steel material containing 0.5% by mass or more of carbon with a wire diameter corresponding to the wire diameter of the high carbon steel wire for springs of the final product is prepared for the final wire drawing. The patenting process is applied.

  By using a high carbon steel wire containing 0.5% by mass or more of carbon, it is possible to obtain mechanical characteristics necessary as a spring steel wire after wire drawing. As such a high carbon steel wire, the high carbon steel wire prescribed | regulated to JIS-G-3522 and JIS-G-3521 can be mentioned, for example. In addition, since drawing process (drawing process) will become difficult when there is too much content of carbon, it is preferable that it is 1.2 mass% or less.

  As specific patenting conditions, generally, heating at 900 to 1000 ° C. and lead patenting treatment or fluidized bed patenting treatment at 500 to 580 ° C. are preferable.

(2) Plating process Next, the patented high carbon steel wire is electrolytically cleaned with sulfuric acid, hydrochloric acid, etc., and then the surface of the high carbon steel wire is plated to form a copper alloy layer or a copper layer. To do.

(3) Wire drawing process Finally, with a die, the high carbon steel wire having a copper alloy layer or a copper layer formed on the surface by plating treatment has a predetermined wire diameter with a total area reduction of 75% or more. A high-carbon steel wire for a spring having a copper alloy layer or a copper layer formed on the surface is obtained by performing wet drawing or dry drawing.

  As described above, by forming a copper alloy plating layer or a copper plating layer on the surface of the high carbon steel wire, and then performing wire drawing, the following great effects can be obtained.

  Copper alloys and copper are excellent in corrosion resistance and solderability. And the gold or copper color appearance by these metal layers is superior to the silver color darkened by a lubricating film such as phosphate or lime, especially in the case of wet wire drawing of copper alloy plating such as brass. It is beautiful. In addition, even when a spring with a similar shape is incorporated into a part by an automobile parts manufacturer, etc., it is possible to identify by the plating surface color, and it is possible to prevent wrong types of springs from being incorporated by mistake. It also has the following features.

  In addition, since these metal layers have a low coefficient of friction against the wire drawing dies, the life of the wire drawing dies is greatly improved during wire drawing by forming these metal layers prior to the wire drawing process. And can be drawn at a high drawing speed.

  In addition, the life of the wire drawing dies can greatly reduce the die cost, especially the cost of natural diamond dies and artificial diamond dies, which is combined with the improvement in productivity accompanying the wire drawing speed. Thus, it is possible to sufficiently absorb the increase in cost due to the provision of the plating step and greatly reduce the manufacturing cost of the high carbon steel wire for springs as a whole.

  And such a cost reduction effect is exhibited greatly when manufacturing a long high carbon steel wire for a spring with a small diameter of 1.0 mmφ or less, especially 0.5 mmφ or less by wire drawing. Particularly in the manufacture of precision springs, a high carbon steel wire for springs with a stable wire rod is essential, and it is necessary to use natural diamond dies or artificial diamond dies, so that the cost reduction effect is particularly remarkable.

  The high carbon steel wire for springs manufactured in this way has a copper alloy layer or copper layer formed on the surface of the high carbon steel wire. Therefore, high-speed coiling is possible, and seizure and galling occur, and variations in the shape of the spring are reduced, so that the yield in coiling is improved.

  Also, by providing a copper alloy layer or copper layer, the surface of the high-carbon steel wire for springs can be colored gold or copper, and the appearance of the high-carbon steel wire for springs has been improved from the black silver color typical of steel wires. can do. In addition, similar shaped springs can be identified by the plating surface color.

  In the present embodiment, as a specific plating method for forming a copper alloy layer or a copper layer, it is preferable to use electroplating because formation of a copper alloy layer or a copper layer by hot dipping is difficult.

  Specific plating solutions for electrolytic copper plating include, for example, plating solutions such as copper phosphate.

  In addition, after electroplating of copper, if necessary, further, electrogalvanizing is performed in a plating solution such as zinc sulfate and zinc chloride, and then diffusion treatment is performed at 530 to 600 ° C. to form a copper alloy layer. May be.

  In addition, although this inventor examined adoption of various metal layers other than a copper alloy and copper as a metal layer formed in the surface of a high carbon steel wire, all have various problems and the above-mentioned effect. I got the conclusion that I can't get it.

  For example, as metals that improve corrosion resistance and soldering properties, there are noble metals such as gold and silver. Although these metals are excellent in corrosion resistance, they are too expensive, and the overall production cost is high, so that they are industrially used. There is no merit to use.

  In addition, nickel is expensive and has less effect of improving corrosion resistance and solderability than copper alloy and copper, and has little effect of improving die life even in wire drawing using a die after plating.

  Moreover, although lead is excellent in wire drawing workability, it cannot be used because it is a harmful metal.

  In addition, although zinc has a cathodic protection effect, it has a higher ionization tendency than steel, so it corrodes (oxidizes) early and cannot maintain corrosion resistance for a long period of time. And since zinc itself becomes a sacrificial anode and corrosion products such as zinc oxide are formed, the appearance is impaired.

  As the thickness of the copper alloy plating layer or copper plating layer formed in the present embodiment, the thickness of the plating layer after wire drawing is performed with a total area reduction of 75% or more is 0.1 It is preferable to control so that it may become -1.6 micrometers.

  If a plating layer that is too thin so that the thickness of the plating layer after wire drawing is less than 0.1 μm is formed, defects such as pinholes may occur in the plating layer. For springs after wire drawing There is a risk of causing a decrease in corrosion resistance in high carbon steel wires. That is, since the steel in the ground is inferior in corrosion resistance compared to copper alloys and copper, the presence of defects such as pinholes causes the steel in the ground to be preferentially corroded, thereby preventing the corrosion of the high carbon steel wire for springs as a whole. The effect is reduced. Moreover, in such a defective part, there exists a possibility that local corrosion reaction may accelerate | stimulate.

  And it becomes difficult to keep the wire drawing workability by a die | dye favorable, and the solderability of the high carbon steel wire for springs which carried out the wire drawing process also falls. Further, the coiling workability cannot be sufficiently improved.

  In order to achieve better corrosion resistance, solderability, wire drawing workability, and coiling workability, the plating layer is formed so that the thickness of the plating layer after wire drawing is 0.2 μm or more. It is preferable to do.

  On the other hand, even if a plating layer that is too thick after wire drawing is formed, the corrosion resistance, solderability, and effects associated with the formation of the plating layer are saturated. Result. And wire drawing workability also falls. Also, if the thickness of the plating layer is too thick, it will cause an increase in the cross-sectional area ratio of copper alloy and copper, which is one order of magnitude lower than that of high carbon steel. It becomes difficult to maintain. Specifically, it must be 1.6 μm or less, and preferably 1.4 μm or less.

  From the above, the thickness of the plating layer after wire drawing to a wire diameter of 1.0 mmφ or less is preferably 0.1 to 1.6 μm, and more preferably 0.2 to 1.4 μm.

  In this embodiment, the reason why the wire drawing is performed with a total area reduction of 75% or more is to obtain the strength necessary for the steel wire for springs.

  And it is also preferable to attach the inorganic salt or polymer resin film to the surface of the plating layer (copper alloy layer or copper layer) before or after the wire drawing process, and attach these films. Thus, it is possible to further reduce the friction between the wire drawing die and the high carbon steel wire during wire drawing, further improve the coiling workability, or further improve the corrosion resistance.

  As described above, in the present embodiment, prior to wire drawing, by forming a copper alloy layer or a copper layer with an appropriate thickness on the surface of the high carbon steel wire, the wire drawing cost, corrosion resistance, Solderability, coiling workability, and appearance can also be improved, and a significant effect that has never been achieved can be obtained.

  In addition, if the above-mentioned wire drawing cost is demonstrated, in the present invention, since a process of plating a copper alloy or copper is added, it is considered that the cost is increased as compared with the conventional process. However, when a copper alloy or copper plating is applied and the die is drawn as in the present invention, the wire drawing workability ( (Lubricity) is much better. For this reason, the die life is improved in the finish wire drawing step, and the wire drawing speed can be increased.

  As a result, the length of the steel wire usually increases in proportion to the square of the weight of the steel wire, so that the smaller the diameter, the larger the number of dies required. In the present invention, the amount of dies used is reduced. The cost reduction effect by this can be exhibited greatly.

  The inventors have found that the finished wire diameter is generally 1.0 mmφ or less, and that the cost reduction due to the wire drawing speed improvement and the long life of the die is greater than the cost increase due to plating. In particular, when the finished wire diameter is 0.5 mmφ or less (including the thickness of the metal layer), the amount of dies used per unit weight of the steel wire increases rapidly, and a large amount of diamond dies must be used. Further, the effect of reducing the manufacturing cost of the high carbon steel wire for spring as a whole is further increased.

  Hereinafter, the present invention will be described in more detail based on specific examples.

(1) Patenting process First, in the manufacturing process for mass production of piano wire using SWRS-82B wire containing 0.81% carbon in SWP-A defined in JIS-G-3521, the heating temperature Patenting treatment was performed under general patenting conditions of 910 ° C. and fluidized bed temperature 510 ° C., and a high carbon steel wire having a wire diameter of 1.50 mmφ after final patenting was prepared.

(2) Plating step Next, the high-carbon steel wire subjected to the patenting treatment was pretreated (electrolytic cleaning) with sulfuric acid, and then copper pyrophosphate (PH: 9.8, temperature: 50 ° C., Cu concentration: 32 g / l) Electroplating is performed using the solution as a plating solution, and zinc sulfate (PH: 2.9, temperature: 45 ° C., Zn concentration: 1.5 g / l) is formed on the copper plating layer of each high carbon steel wire. Electrogalvanizing using the solution, and adjusting the immersion time of the high carbon steel wire in the plating solution, the total thickness of the surface of the high carbon steel wire is 1 μm (Example 1), 4 μm (Example 2). ), 7 μm (Example 3), 10 μm (Comparative Example 1), copper alloy plating layers having different thicknesses were formed, and diffusion treatment was performed at 560 ° C., thereby forming the plating layer as a copper zinc alloy 4 A kind of high carbon steel wire was obtained. The copper ratio of the copper zinc alloy was 65%.

(3) Wire drawing step Each of the high carbon steel wires obtained in Examples 1 to 3 and Comparative Example 1 obtained above and the high carbon steel wire (Comparative Example 2) in which the copper-zinc alloy plating layer was not formed were each 10 t. Prepare and use all sintered diamond dies as dies, assemble a die series with an average area reduction rate of 20% per die, and set the drawing speed to 500 m / min. Drawing was performed until the diameter became 0.35 mmφ. The thicknesses of the copper-zinc alloy plating layers in each high carbon steel wire after wire drawing are 0.2 μm (Example 1), 0.9 μm (Example 2), 1.5 μm (Example 3), 2 0.0 μm (Comparative Example 1).

  In this wire drawing process, in Examples 1 to 3, the wire could be drawn to 0.35 mmφ without any occurrence of seizure and wire diameter abnormality. On the other hand, in the case of Comparative Example 1 where the thickness of the plating layer before drawing was as thick as 10 μm, plating peeling occurred in the middle of drawing, so that only 50 kg could be drawn. In the case of Comparative Example 2 where plating was not performed, seizure occurred in the middle of wire drawing, so that only 420 kg could be drawn.

  From this result, by forming a copper-zinc alloy plating layer with an appropriate thickness on the high carbon steel wire before wire drawing, even if wire drawing is performed at a high wire drawing speed of 500 m / min, the entire amount, seizure, wire Since no diameter abnormality occurred, it was confirmed that a sufficient die life could be secured and a large amount of high carbon steel wire could be drawn, and the wire drawing workability was improved.

  In addition, about the high carbon steel wire of Example 1, all were drawn with the same die series using an alloy die, and 5t could be drawn. Even when an alloy die was used, a sintered diamond die was used. Although it was not possible to achieve this, it was confirmed that a sufficient die life could be secured and the wire drawing workability improved.

(4) Confirmation of wire rod Next, for each high carbon steel wire after drawing, a predetermined sample is cut out from the coiled wire grip after drawing, and the wire rod of each high carbon steel wire becomes a steel wire for spring. Confirmed that it is in the range that is generally managed as.

  That is, the coil has a diameter of 250 to 300 mm when a wire is cut and placed on a table without being bound, and the height of the lift of the end when a wire is cut and placed on a table without being tied It was confirmed that it was 10 mm or less, and when the five windings were cut out, the same part of each winding was cut and supported at the center of each winding, the maximum variation difference generated at the end was 20 mm or less.

(5) Evaluation of each high carbon steel wire after wire drawing Next, each of the following characteristics was evaluated for each high carbon steel wire after wire drawing. Each evaluation result is shown in Table 1.

(A) Tensile properties Tensile properties (tensile strength) of each high carbon steel wire after wire drawing were measured according to JIS-Z-2241 (metal material tensile test method).

(B) Corrosion resistance Each high carbon steel wire after drawing was exposed to the general atmosphere in the northern residential area of Nishinomiya City for 30 days, and the number of days when red rust of iron began to occur on each high carbon steel wire (however, (Not including discoloration).

(C) Solder adhesion force A 0.36φ hole was made in a copper plate, each high-carbon steel wire after drawing was passed through, and a commercially available spicy eutectic yarn solder (GXM3) was used, and the fillet height was 1.5 mm. Only one side was soldered so that it was constant. Solder adhesion force is the load by which the steel wire is pulled out from the solder when the copper plate is fixed, the steel wire is fixed to the hook with springs, with the unsoldered side up, and the springs are pulled upwards. Was evaluated as the solder adhesion between the steel wire and the copper plate.

  From the results shown in Table 1, each of the high carbon steel wires obtained in Examples 1 to 3 has the same mechanical properties (tensile properties) as a piano wire satisfying the SWP-B standard defined in JIS-G-3522. It was also confirmed that it has excellent corrosion resistance and solder adhesion.

(6) Spring coiling workability Next, using a high-speed automatic coiling machine manufactured by Mecco Machinery as a spring coiling machine, from each high carbon steel wire after drawing, the spring coil center diameter: 3.5 mm (the coil inner diameter is 3. mm). 15 springs having a shape of 15 mm), the number of turns: 12, and the free length (compression spring height): 14 mm were manufactured at a rate of 100 pieces / minute and 200 pieces / minute, respectively.

  Then, in the measurement of the free length by the automatic length detector set in the spring coiling machine, when a deviation of 0.1 mm or more from the desired free length (14 mm) is detected, this spring is rejected as a defective product. The yield of good products (%) in each example and comparative example was determined, the spring coiling yield was measured, and the spring workability was evaluated. The results are shown in Table 2. In Table 2, the thickness of the copper-zinc alloy plating layer is shown again.

(7) Low temperature annealing of spring (tempering)
About each steel wire spring obtained above, in order to remove the residual stress introduced at the time of coiling and maintain the restoring force of the spring, and to suppress deterioration of sag characteristics, Heating was performed (low temperature annealing). And about each steel wire spring after low-temperature annealing, it was measured whether the discoloration by atmospheric oxidation had arisen on the surface of the copper zinc alloy plating layer. The results are shown in Table 2.

  From the results shown in Table 2, each of the high carbon steel wires obtained in Examples 1 to 3 is excellent in spring coiling workability, and further, discoloration due to tempering does not occur and is preferable as a steel wire for springs. It could be confirmed.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

Claims (6)

A patenting process for patenting a high carbon steel wire containing 0.5% by mass or more of carbon;
A plating process for performing copper alloy plating or copper plating on the patented high carbon steel wire;
The high carbon steel wire that has been plated is drawn with a dry or wet die at a total area reduction of 75% or more, and drawn to a thin diameter of 1.0 mmφ or less. Process,
The high carbon steel wire for springs, wherein the plating step is a plating step in which the plating thickness is controlled so that the plating thickness after the wire drawing step is 0.1 to 1.6 μm. Manufacturing method. Before the wire drawing step or after the wire drawing step,
The method for producing a high carbon steel wire for a spring according to claim 1, further comprising a film attaching step for attaching an inorganic salt or polymer resin film to the surface of the plating.   It manufactures using the manufacturing method of the high carbon steel wire for springs of Claim 1 or 2, Comprising: On the surface of the said high carbon steel wire, a 0.1-1.6-micrometer-thick copper alloy layer or copper layer A high carbon steel wire for springs, characterized in that is formed.   The high carbon steel wire for spring according to claim 3, wherein the copper alloy layer or the copper layer has a thickness of 0.2 to 1.4 μm.   5. The high carbon steel for spring according to claim 3, wherein a wire diameter including a thickness of the copper alloy layer or the copper layer and a thickness of the coating is 0.5 mmφ or less. line. It is manufactured using the manufacturing method of the high carbon steel wire for springs according to claim 1 or 2.
A copper-zinc alloy layer having a thickness of 0.2 to 1.6 μm is formed on the surface of the high carbon steel wire,
A high carbon steel wire for a spring, wherein a wire diameter including a thickness of the copper zinc alloy layer and the coating is 0.5 mmφ or less.