JP2007182610A - Stainless steel wire for spring and coil spring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stainless steel wire for a spring, which is excellent in workability when it is formed into the spring although it does not contain nickel, and to provide a coil spring. <P>SOLUTION: The stainless steel wire for the spring is obtained by drawing a stainless steel wire on which a phosphate coating film having a coating film amount of 6.0-14.5 g/m<SP>2</SP>is formed. The surface roughness of the stainless steel wire for the spring is 1.5-2.3 μm. The stainless steel wire for the spring which hardly causes seizing or the like and on which a lubricant is uniformly and surely stuck can be obtained by applying the phosphate coating film having fine unevenness and setting the coating film amount of the phosphate coating film and the surface roughness to the values, respectively. When the coil spring is formed, the coil exhibits excellent workability by using the stainless steel wire for the spring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stainless steel wire for a spring and a coil spring.

In general, it is known that stainless steel wires are inferior in workability compared to carbon steel wires. Therefore, as a stainless steel wire for a spring, for example, as described in Patent Document 1, after applying nickel plating to a stainless steel wire for the purpose of improving workability at the time of forming a spring, a lubricant is attached. The drawn wire has been used.
Japanese Patent No. 3053789

  In the spring stainless steel wire of Patent Document 1, nickel plating waste liquid is discharged during production. Nickel plating waste liquid contains many harmful substances. Therefore, processing of nickel plating waste liquid requires a great deal of cost. Moreover, since nickel is an expensive metal, the material cost is high.

  However, in the case of a stainless steel wire for a spring provided with a film made of a water-soluble material or a resin material instead of nickel plating, the workability at the time of spring forming is lowered. As a result, the obtained spring has a variation in free length and the like.

  Therefore, an object of the present invention is to provide a stainless steel wire for springs and a coil spring that are excellent in workability at the time of spring forming without using nickel.

The stainless steel wire for springs of the present invention is obtained by drawing a stainless steel wire on which a phosphate coating having a coating amount of 6.0 to 14.5 g / m ² is formed. It is 5 to 2.3 μm.

By setting the coating amount of the phosphate coating to 6.0 g / m ² or more, the coating has a sufficient thickness, so that a stainless steel wire for springs without seizure during wire drawing can be obtained. When the coating amount of the phosphate coating is 14.5 g / m ² or less, the coating is not too thick, and it is difficult for clogging of dies during wire drawing. Therefore, a stainless steel wire for a spring having a uniform surface state can be obtained. The stainless steel wire for springs having a uniform surface state with no seizure has good workability and can be smoothly formed.

  The phosphate film has fine irregularities. Therefore, the lubricant can be sufficiently adhered to the stainless steel wire before drawing. By setting the surface roughness after drawing to 1.5 μm or more, a stainless steel wire for springs whose surface is not too flat can be obtained. Further, by setting the surface roughness after drawing to 2.3 μm or less, it is possible to obtain a stainless steel wire for springs whose surface is not too rough. In this way, the lubricant remains almost uniformly and reliably on the stainless steel wire for springs having an appropriate surface roughness. If it is a stainless steel wire for a spring in which the lubricant remains uniformly and reliably, spring forming can be performed more smoothly.

  Therefore, a stainless steel wire for springs excellent in workability at the time of spring forming can be obtained without using nickel.

Preferably, the surface of the stainless steel wire is covered with the lubricant used at the time of wire drawing, and the adhesion amount of the lubricant to the surface is 1.1 to 1.3 g / m ² . Since 1.1 g / m ² or more of the lubricant is adhered, it is possible to suppress friction with the jig at the time of spring molding, and stick stick and seizure can be prevented. Since the adhesion amount of the lubricant is 1.3 g / m ² or less, it is possible to suppress a situation where the spring stainless steel wire slips during spring forming and cannot be properly held by a jig. Therefore, it is difficult to cause a problem when forming the spring, and it is possible to reliably obtain a spring with little variation in free length.

  Preferably, the phosphate film on the stainless steel wire is formed by electrolytic treatment. In this case, a stainless steel wire in which a phosphate film is uniformly formed can be obtained. Therefore, a stainless steel wire for springs with good workability can be obtained more reliably.

  Preferably, the stainless steel wire is galvanized, and a phosphate film is formed on the galvanized plate. In this case, the adhesiveness of the phosphate film can be improved.

  The coil spring of the present invention is characterized by comprising the above-described stainless steel wire for springs. Thus, by using the stainless steel wire for springs described above, workability can be improved without using nickel when forming a coil spring.

  According to the present invention, it is possible to provide a stainless steel wire for a spring excellent in workability at the time of forming a spring without using nickel. Therefore, if the stainless steel wire for springs of the present invention is used, a coil spring with little variation in free length can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  FIG. 1 is a perspective view of a coil spring using a spring stainless steel wire according to the present embodiment. A coil spring S1 shown in FIG. 1 is obtained by winding a stainless steel wire W1 for a spring. The spring stainless steel wire W1 is obtained by drawing a stainless steel wire on which a phosphate film is formed.

  FIG. 2 is a diagram showing a method of manufacturing the spring stainless steel wire W1. As shown in FIG. 2, when producing the spring stainless steel wire W1, first, the stainless steel wire fed from the supply reel is bent by a mechanical descaler or the like (step S21). After bending, the stainless steel wire is pickled to remove oxides attached to the surface of the stainless steel wire (step S22). For pickling, an electrolytic method or a non-electrolytic method (batch method) can be used, but in this embodiment, an electrolytic method using a stainless steel wire as a cathode is applied.

  After pickling, the stainless steel wire is washed with water to wash away the acid solution (step S23). After washing with water, the stainless steel wire is galvanized as necessary (step S24). Zinc plating is performed by electrolysis. By applying galvanization, the adhesion of the phosphate film can be improved.

Subsequently, phosphate film formation is performed (step S25). For the phosphate film formation, an electrolytic method or a non-electrolytic method (batch method) can be used, but in this embodiment, an electrolytic method using a stainless steel wire as a cathode is applied. By performing the pickling treatment and the phosphate film chemical conversion treatment by an electrolytic method, a stainless steel wire having a phosphate film uniformly attached can be obtained. The film amount of the phosphate film to be formed is 6.0 to 14.5 g / m ² . When the coating amount is smaller than 6.0 g / m ² , the coating is excessively thin, so that the stainless steel wire is easily seized during wire drawing. When the coating amount is greater than 14.5 g / m ² , the coating is excessively thick, and thus clogging of the dies is likely to occur during wire drawing. It becomes difficult to obtain.

  Subsequently, the stainless steel wire on which the phosphate film is formed is washed with hot water (step S26). Hot water washing is performed for the purpose of rinsing out the acid solution and promoting the formation of a phosphate film. After the hot water washing, the stainless steel wire is dried (step S27). Then, a lubricant is attached to the dried stainless steel wire, and the wire is drawn using a die (step S28). As described above, the stainless steel wire W1 for spring is obtained. The obtained spring stainless steel wire W1 is wound around a take-up reel.

  In the manufacturing method described above, the surface roughness of the spring stainless steel wire W1 is adjusted to 1.5 to 2.3 μm. If the surface roughness is less than 1.5 μm, the surface is excessively flat, so much of the lubricant adheres to the die during wire drawing, and spring stainless steel with almost no lubricant remaining There is a possibility of becoming the line W1. When the surface roughness is larger than 2.3 μm, the surface is excessively rough, and there is a possibility that the stainless steel wire W1 for springs with non-uniform dispersion of the lubricant may be obtained. The spring stainless steel wire W1 whose surface roughness is adjusted to 1.5 to 2.3 μm has the lubricant uniformly and reliably attached to the surface. Therefore, the coil spring S1 can be formed smoothly.

Furthermore, in said manufacturing method, it adjusts so that the adhesion amount of the lubrication agent in the stainless steel wire W1 for springs may be 1.1-1.3g / m < ² >. If the adhesion amount of the lubricant is smaller than 1.1 g / m ² , the friction between the spring stainless steel wire W1 and the jig becomes large when the coil spring S1 is formed. As a result, stick slip and seizure are likely to occur. When the adhesion amount of the lubricant is larger than 1.3 g / m ² , the spring stainless steel wire W1 slips when the coil spring S1 is formed, and it becomes difficult to hold it by the jig. By adjusting the adhesion amount of the lubricant to be 1.1 to 1.3 g / m ² , it is possible to obtain a spring stainless steel wire W1 that is less likely to cause problems during spring formation.

  Next, a method for forming the coil spring S1 will be described. FIG. 3 is a schematic configuration diagram showing a coiling machine for manufacturing the coil spring S1. According to this coiling machine M1, the stainless steel wire W1 for spring fed out from the take-up reel is corrected by the roller 1 into a substantially straight line. The straightened stainless steel wire W1 for spring is guided by the wire guide 3 according to the rotation of the feed roller 2, bent by the coiling pin 4 along the mandrel 5, and wound. During this time, the pitch between the windings is set to a predetermined value by the pitch tool 6, and when the predetermined number of turns are wound, the spring stainless steel wire W <b> 1 is cut by the cutter 7. In this way, the coil spring S1 is formed.

As described above, the spring stainless steel wire W1 is obtained by drawing a stainless steel wire on which a phosphate film is formed. Since the coating amount of the phosphate film before wire drawing is 6.0 to 14.5 g / m ² , no seizure or clogging of dies occurs during wire drawing. Therefore, the stainless steel wire W1 for springs without damage can be obtained. Since the phosphate film has fine irregularities, the lubricant can be sufficiently adhered to the stainless steel wire before drawing. By setting the surface roughness after drawing to 1.5 to 2.3 μm, it is possible to obtain the spring stainless steel wire W1 in which the lubricant remains reliably and uniformly. Thus, the stainless steel wire W1 for springs which is not damaged and the lubricant remains reliably and uniformly becomes excellent in workability at the time of spring forming.

  Here, the following experiment was performed in order to confirm that the stainless steel wire W1 for springs of this embodiment is excellent in workability at the time of spring forming.

In order to confirm that the stainless steel wire W1 for springs was excellent in workability at the time of spring forming, first, a stainless steel wire to which a phosphate film was applied was prepared. A stainless steel wire having a diameter of 3.45 mm was used. The pickling was sulfuric acid pickling, the current density during pickling was 19.6 A / dm ² or 39.5 A / dm ² , and the immersion time during pickling was 8 seconds or 17 seconds. In addition, a solution containing phosphate ions 20 to 70 g / l, zinc ions 20 to 50 g / l, nitrate ions 30 to 80 g / l, and maintained at a temperature of 75 to 85 ° C. is used for phosphate film formation. Using. In this case, the formed phosphate film is a zinc phosphate film. The current density during phosphate film formation was 3.0 to 12.9 A / dm ² , and the immersion time during phosphate film formation was 8 seconds or 17 seconds. In the case of applying galvanization, the plating amount was 2.6 g / m ² . Table 1 shows the coating amount of the formed phosphate coating.

The film amounts of Examples 1 to 5 were 6.0 to 14.5 g / m ² . On the other hand, the coating amount of Comparative Example 1 was 3.3 g / m ² , and the coating amount of Comparative Example 2 was 18.1 g / m ² .

  Next, the stainless steel wires of Examples 1 to 5 and Comparative Examples 1 and 2, the stainless steel wire plated with nickel by the electrolytic method, and the stainless steel wire coated with a potassium sulfate film as a water-soluble film. Prepared. A calcium stearate-based powder lubricant was adhered to these prepared steel wires, and after continuous drawing with a multi-stage cemented carbide die, further drawing was performed with a sintered diamond die. Thus, a spring steel wire having a diameter of 1.00 mm was obtained. The obtained stainless steel wire for spring was measured for the surface roughness and the adhesion amount of the lubricant.

  Here, the surface roughness is a ten-point average roughness (Rz). That is, as shown in FIG. 4, in the portion extracted from the cross-section curve by the reference length, the peak from the highest to the fifth measured in the direction of the vertical magnification from the line parallel to the average line and not crossing the cross-section curve. The value of the difference between the average value of the altitude and the average value of the altitude of the bottom valley from the deepest to the fifth is expressed in micrometers (μm).

The results measured as described above are shown in Table 2.

Examining the measurement results, the stainless steel wires for springs of Examples 1 to 5 have a surface roughness of 1.5 to 2.3 μm and a lubricant adhesion amount of 1.1 to 1.3 g / m ² . there were. The spring stainless steel wire of Comparative Example 1 had a surface roughness of 1.0 μm and a lubricant adhesion amount of 0.5 g / m ² . The stainless steel wire for springs of Comparative Example 2 had a surface roughness of 2.3 μm and a lubricant adhesion amount of 2.0 g / m ² . The stainless steel wire for springs of Comparative Example 3 had a surface roughness of 3.5 μm and an adhesion amount of lubricant of 2.1 g / m ² . The spring stainless steel wire of Comparative Example 4 had a surface roughness of 3.3 μm and a lubricant adhesion amount of 3.0 g / m ² .

After measuring the surface roughness and the adhesion amount of the lubricant, coil springs were formed using the stainless steel wires for each spring. More specifically, 300 springs were formed from the stainless steel wires for springs of Examples 1 to 5 and Comparative Examples 1 to 4, respectively, using the coiling machine M1 described above. And the free length average and standard deviation of the obtained coil spring were measured. The center diameter of the coil spring is 10.0 mm, the total number of turns is 8.5, the effective number of turns (the number of turns obtained by subtracting the end turns at both ends from the total number of turns of the coil spring) is 7.5, and the free length is 40.0 mm. . The measured results are shown in Table 3.

  Examining the measurement results, the coil springs using the spring stainless steel wires of Examples 1 to 5 had a free length average of 40.001 to 40.020 mm and a standard deviation of 0.190 to 0.211 mm. It was.

  The coil spring using the spring stainless steel wire of Comparative Example 1 had an average free length of 39.988 mm and a standard deviation of 0.415 mm. The coil spring using the spring stainless steel wire of Comparative Example 2 had an average free length of 39.998 mm and a standard deviation of 0.275 mm. The coil spring using the spring stainless steel wire of Comparative Example 3 had an average free length of 40.111 mm and a standard deviation of 0.185 mm. The coil spring using the spring stainless steel wire of Comparative Example 4 had an average free length of 40.008 mm and a standard deviation of 0.315 mm.

Thus, the stainless steel wires for springs of Examples 1 to 5 had the same free length average and standard deviation as the stainless steel wires for springs of Comparative Example 3 to which nickel plating was applied. Therefore, it is obtained by drawing a stainless steel wire having a phosphate coating amount of 6.0 to 14.5 g / m ² and has a surface roughness of 1.5 to 2.3 μm. It was found that a coil spring with little variation in free length can be obtained from a stainless steel wire for springs having an adhesion amount of 1.1 to 1.3 g / m ² . Thereby, it was confirmed that the stainless steel wire W1 for springs of this embodiment is excellent in workability at the time of spring forming.

  Here, in Comparative Examples 1 and 2, the reason why the yield rate of the coil spring is lower than those in Examples 1 to 5 is examined.

In the spring stainless steel wire of Comparative Example 1, the coating amount before drawing is as small as 3.3 g / m ² . Therefore, the film is further thinned at the time of wire drawing, and as a result, seizure easily occurs. In addition, the spring stainless steel wire having an excessively thin coating is easily damaged by a jig during spring processing, and as a result, the possibility of exposing the stainless steel wire portion inside the coating is increased. In the case of a stainless steel wire for a spring in which seizure or exposure of the stainless steel wire portion is seen, the spring forming is not stable, and the resulting coil spring has variations in free length and the like. Further, the spring steel wire of Comparative Example 1 has a small surface roughness of 1.0 μm. Therefore, the lubricant adhered before wire drawing tends to fall off during wire drawing. As a result, the obtained spring steel wire has a small amount of lubricant adhesion of 0.5 g / m ² . Even when the adhesion amount of the lubricant is small, it is difficult to perform the spring molding smoothly.

In the spring stainless steel wire of Comparative Example 2, the coating amount before drawing is as large as 18.1 g / m ² . Therefore, clogging of the die is likely to occur during wire drawing. As a result, the surface state becomes non-uniform. In a stainless steel wire for springs with a non-uniform surface state, the spring forming is not stable, and the resulting coil spring has variations in free length and the like.

In view of the above, a stainless steel for springs having good workability at the time of spring forming if at least the amount of the phosphate film before drawing and the surface roughness after drawing are appropriate values. Become a line. That is, it is obtained by drawing a stainless steel wire having a phosphate coating amount of 6.0 to 14.5 g / m ² , and the surface roughness after drawing is 1.5 to 2.3 μm. If it is stainless steel for springs, spring shaping can be performed smoothly. Further, when the adhesion amount of the lubricant is the same value as in Examples 1 to 5 (specifically 1.1 to 1.3 g / m ² ) and the phosphate film is formed by electrolytic treatment, the spring It can be said that the workability at the time of molding can be further improved.

  The preferred embodiments of the present invention have been described above, but the present invention is not necessarily limited to these embodiments. For example, in the present embodiment, the coil spring is formed from the spring stainless steel wire, but the spring that can be formed from the spring stainless steel wire of the present invention is not limited to the coil spring.

It is a perspective view of the coil spring using the stainless steel wire for springs concerning this embodiment. It is a figure which shows the manufacturing method of the stainless steel wire for springs which concerns on this embodiment. It is a schematic block diagram which shows a coiling machine. It is a figure for demonstrating ten-point surface roughness.

Explanation of symbols

  W1 ... stainless steel wire for spring, S1 ... coil spring.

Claims (5)

It is obtained by drawing a stainless steel wire on which a phosphate film having a film amount of 6.0 to 14.5 g / m ² is formed, and has a surface roughness of 1.5 to 2.3 μm. Stainless steel wire for springs. ^2. The spring according to claim 1, wherein a surface is covered with a lubricant used at the time of wire drawing, and an adhesion amount of the lubricant to the surface is 1.1 to 1.3 g / m ^2. Stainless steel wire.   The stainless steel wire for springs according to claim 1 or 2, wherein the phosphate film is formed by electrolytic treatment.   The stainless steel wire for spring according to any one of claims 1 to 3, wherein the stainless steel wire is galvanized, and the phosphate film is formed on the galvanized metal. Steel wire.   A coil spring comprising the stainless steel wire for a spring according to any one of claims 1 to 4.

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