JPH0823079B2 - Colored steel spring for easily distinguishing between different products and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to discrimination between different products.
It relates easy colored steel spring and a manufacturing method thereof, in particular, identified with appropriate performed such dimensions and material, the surface
The present invention relates to a colored steel spring capable of improving aesthetics and corrosion resistance and a method for manufacturing the spring .

[0002]

2. Description of the Related Art Steel springs such as coil springs and leaf springs made of steel for springs are used in various fields such as machine parts, office supplies and daily life. The steel material for springs, which is the material of such springs, includes steel wire for springs and steel plate for springs . As steel wires for springs, hard steel wires, piano wires, and stainless steel wires for springs, which are specified in JIS, are known.

The surface colors of these steel wires are relatively similar to each other, and it is impossible to distinguish between the hard steel wire and the piano wire only by the color tone. In addition, stainless steel wire generally has luster compared to hard steel wire and piano wire,
In the case of a wire rod finished by oil drawing (wet wire drawing), it is extremely difficult to identify it by color tone. Therefore, if the size is very similar after spring molding, sometimes dimensional error or material error may occur.
Occasionally, there was a problem that a nonstandard spring product was accidentally incorporated into a mechanical structure.

On the other hand, the steel cord which reinforces the radial tire of an automobile is obtained by twisting 5 strands of 0.25 mm, for example, and knitting these strands in a belt shape and arranging them around the tire circumference. We are strengthening it as a composite material of rubber and metal cords. This wire is plated with Cu on the lower layer and Zn on the upper layer so that the thickness ratio of Cu: Zn is 7: 3 on the surface of the original wire of 1.3 mm, and then heated to about 400 ° C for several minutes. Change the plating layer to an alloy of Cu-30% Zn and further down to 0.25 mm
It is manufactured by 96.3% strong wire drawing. After the above heating during the step, the white plating in appearance changes to golden color and has a very beautiful color tone.

In the production of the above-mentioned steel cord, it is of no value that the surface color tone of the cord changes to a golden color, and the use of a Cu-30% Zn alloy as the plating layer improves the wire drawability and improves the rubber property. The purpose is to improve adhesion with metal. Therefore, a method of plating two kinds of dissimilar metals, heating and diffusing them to form an alloy, and having a function of coloring itself has not been used at all.

[0006]

[SUMMARY OF THE INVENTION] In order to facilitate the identification of the dimensions and material of the steel springs, now covering the various resin coating to the spring steel wire, baking the coating of the paint, PVD, ion such as CVD By plating or coating with TiN, etc., it is colored to facilitate identification and improve aesthetics.

However, the spring steel wire is severely rubbed with the forming tool during the spring forming process so as to cause galling, and the spring steel wire is subjected to 250-400 to improve spring characteristics after the spring forming process.
Since it is heat-treated (low-temperature annealing) for about 2 to 10 minutes at ℃, if the resin film or paint is baked, the surface may be damaged during spring molding and the film may peel off.
Further, even during the low temperature annealing treatment, the coating is softened to form a dent, and the springs are welded to each other. The ion-plated type does not cause such a problem, but has a drawback of high cost, and at present, none of the methods exhibits a sufficient function.

The present invention has been made in view of such circumstances, solves the above problems, and utilizes the above-mentioned conventional technique (steel cord manufacturing technique) to make a spring made of different steel.
It is intended to facilitate the distinction between the areas and to improve the appearance of the surface.

[0009]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies, and as a result, the spring characteristics of the spring steel material are not significantly deteriorated even by the plating treatment, and further, after the spring forming process, The present inventors have completed the present invention by discovering that the color of the plating layer develops during the low temperature heating and annealing, so that it is possible to distinguish between different sizes and different materials of the spring molded product by appropriately selecting the color tone.

That is, the present invention alloys by low temperature heat diffusion after spring forming and develops copper red or golden color.
The purpose is to make a steel spring having a colored Cu-Zn alloy plated layer on its surface. Also, on the surface of the spring steel material, two-layer plating consisting of Cu for the lower layer and Zn for the upper layer is applied to the entire plated layer. The thickness of the Zn layer to the thickness is 5 to 10% or 10 to 45%, then processed into a spring material, and the final plating total thickness is adjusted to 2 to 25 μm. After that, the molded product is molded at 250 ℃ for 4 minutes or more up to 400 ℃
Min. Over a low temperature annealing condition to diffuse Cu-Zn plating layer
Alloyed with copper and colored copper red or golden
Made by forming a colored Cu-Zn alloy plating layer
The gist is the method of manufacturing the spring .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A Cu-Zn alloy plated layer obtained by heating and alloying Cu-Zn two-layer plating can exhibit various surface color tones depending on the heating conditions and Zn%, so that it is easy to identify. . The present invention aims to prevent mixing of different sizes and different materials of a spring molded product by utilizing the difference in color tone of the colored plating layer. Since the properties of the spring molded product are greatly deteriorated due to the presence of the colored plating layer for the purpose, it is unpractical, and therefore the optimum condition is naturally defined even for the colored plating layer. The present invention has been completed based on the findings obtained by thoroughly researching the optimum conditions from the viewpoints of distinguishability and spring characteristics. These will be specifically described below with reference to the drawings.

In FIG. 1, a hard steel wire is subjected to two-layer plating (lower layer Cu, upper layer Zn) so that the upper layer has a thickness of 30% of the total plating thickness, wire drawing, coil spring molding, and various It is an example of the result of examining the change in color tone of the plating surface during heating at temperature and time. The change in color tone has a close relationship with the heating temperature and the heating time, and when the conditions are satisfied, the change from white to a visually recognizable golden color occurs almost instantly, which is a practical low temperature annealing temperature of a spring. 250 to 400 ° C
Shows that the color tone changes at 250 ℃ for 4 minutes or longer and at 400 ℃ for 2 minutes or longer. When various experiments were conducted, 25
It was revealed that the heating and holding time required to cause the above-mentioned color tone change at the temperature T (° C) of 0 to 400 ° C is the time t (min.) That satisfies the following formula.

Logt ≧ 1.193−2.386 × 10 ⁻³ T

FIG. 2 shows that after various plating thicknesses are changed and the same plating as described above is performed, wire drawing and spring molding are performed in the same manner, 4
Fig. 3 shows the relationship between the amount of Zn (%) in the alloy and the color tone by forming a spring having a Cu-Zn alloy plating layer by heating at 00 ° C for 5 minutes. In the range of 10 to 45% Zn, the color tone is a beautiful golden color, and it is a color tone that is suitable for performing identification to prevent mixing of different size springs and different materials, and the aesthetic appearance is also significantly improved.
Also, in the range of 5 to 10% Zn, the color tone is strongly influenced by the plating component Cu (red copper color), but as-plated white (Zn
Since it has a distinctly different color tone compared to that of the spring), it can be sufficiently distinguished from a spring having a normal white (metal color) surface, and has practicality.

By the way, it is one of the important properties that a steel spring has excellent corrosion resistance. Therefore, FIG.
For springs similar to, Zn (%) in the Cu-Zn alloy plating layer
And the time required for red rust to be generated by spraying with 3% salt water (time for corrosion to reach the material), and the results are shown in FIG. When the plating layer thickness is 2 μm or more, the corrosion resistance improves with the increase of Zn%, and the one with 5 to 45% Zn has a longer red rust occurrence time than the untreated (non-plated) hard steel wire. Without deteriorating the characteristics of the
On the contrary, it turns out that it can be improved. When the thickness of the plating layer is 1 μm, it is affected by the unevenness of the surface of the spring base material, and the effect of improving corrosion resistance is not achieved. The rusting time when SUS304 stainless steel wire is used instead of the hard steel wire as the spring wire is the rusting time of the SUS304 stainless steel wire spring itself (185hr).
3 is added to the value in FIG.

FIG. 4 is a schematic diagram of a 3.5 mmφ hard piano wire with Cu-
Relationship between hunter type rotary bending fatigue strength and Zn% of wire when alloyed by applying 2 layer plating of Zn, 91.7% wire drawing to 1mmφ and heating at 400 ° C for 5 minutes ,
In addition, the results are also shown for the case where a 2.5 mmφ stainless steel wire is similarly plated with two layers, and then 84% wire drawing is performed to heat a wire rod having a diameter of 1 mmφ to alloy the plated layer.
For both piano wire and stainless steel wire, it is almost unnecessary to consider the fatigue strength decrease up to a plating layer thickness of 25 μm, whereas a clear decrease in fatigue strength is observed at 30 μm. Therefore, it is practically desirable to perform plating with a layer thickness of 25 μm or less. This also applies to coil springs (spring steel molded products).

The above data shows that the spring steel material is a wire rod and is made of steel.
As for the case where the spring is a coil spring ,
In other cases, for example, when the spring steel material is a plate material and the steel spring is a plate spring, the result has the same tendency as described above.

To summarize the above points, regarding the colored Cu-Zn alloy plating layer on the surface of the steel spring , the Cu-Zn alloy composition is in the range of 5 to 45% Zn from the viewpoint of color tone effect, and the plating thickness is corrosion resistant. 2 μm or more from the viewpoint, 25 μm from the viewpoint of preventing fatigue strength deterioration
On the other hand, the low temperature annealing condition for color development is preferably 250 ° C. for 4 minutes or more to 400 ° C. for 2 minutes or more.

The colored steel spring and the manufacturing method thereof according to the present invention are constructed in consideration of such points (conditions). Therefore, the colored Cu--Zn composite is not deteriorated without deteriorating the characteristics of the steel spring. The color tone effect of the gold-plated layer is exerted, the identification of the steel spring can be facilitated, and the surface aesthetic appearance can be improved.

In the manufacturing method according to the present invention, the spring steel material is subjected to two-layer plating (lower layer: Cu, upper layer: Zn) and processed into a spring material so as to satisfy the above points (conditions). It is a method of forming a colored steel plate according to the present invention by a method in which the plated layer is colored while being heat-treated at a temperature of 250 to 400 ° C. and annealed at a low temperature after being formed into a sheet. However, the colored steel spring according to the present invention can be manufactured by a method other than this method, for example, 250 to 400 after processing the above spring material and before spring forming.
It can also be manufactured by a method of heating to a temperature of ° C to develop the color of the plated layer, and then performing spring forming and low-temperature annealing. However, in this method, the heating step is increased by one step and the manufacturing process is complicated, whereas the method of the present invention causes the plating layer to develop color by low temperature annealing which is indispensable after the spring forming process.
Therefore, it can be said that the manufacturing process is simple and economical.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

(Example) (Example 1) A hard steel wire containing 0.82% C: lead patented, pickled, and descaled to obtain a 3.5 mmφ original wire, and a lower layer of Cu and an upper layer of Zn are used as a base.
Layer plating was performed using a two bath continuous electroplating bath. At this time, for Cu plating, the bath composition was CuSO ₄ : 130 g / l, 62% H ₂ SO ₄ : 33
cc / l aqueous solution, pH was 1.5, temperature was 30 ° C., plating current density was 5 A / dm ² , and a Cu plate was used as the anode. Zn plating the bath composition _{ZnSO 4 · 7H 2 O: 410g} / l, AlCl 3 · 6H 2 O: 20g /
l, Na ₂ SO ₄ : 75 g / l aqueous solution, pH: 4, current density was 5 A / dm ² , and a Zn plate was used as the anode. The plating time was changed to 5 types in order to change the Zn thickness ratio and the like as described below. That is, the Zn thickness ratio to the total thickness of the two-layer plating is 0, 5,
It was changed to 5 types of 30, 45 and 50%. At the same time, the total plating thickness was adjusted so that the total plating thickness after drawing was 2, 25 and 30 μm.

After the above-mentioned two-layer plating, the wire is subjected to a wire drawing process of 91.7% up to 1 mmφ by ordinary wire drawing 8 times and JIS 3521 hard steel wire SW
A wire having a C strength level of 1 mmφ was obtained. After forming the 1mmφ element wire into a contact spring with an outer diameter of 10mm, a length of 20mm and a winding number of 20, the temperature is 150 ° C for 7 minutes, 200 ° C for 5 minutes, and 250 ° C for 4 minutes.
After heating for 3 minutes at 300 ° C. for 3.5 minutes and at 400 ° C. for 2 minutes, the color development state was examined. After the heating, it was cooled, and the corrosion resistance was examined by a salt spray test. Further, the tensile strength, the twist value, and the fatigue strength of the 1 mmφ wire subjected to the same heat treatment as above were measured. Table 1 shows the results.

As a comparative example, 1 from the 3.5 mmφ original wire
The bare wire obtained by wire drawing to mmφ and the 3.5mmφ hard steel wire are patented, then drawn to 1mmφ, the polyester paint is dissolved in thinner and immersed in a diluted solution, and baked. 2 bake, 2 coat method,
The same test as above was performed on the obtained polyester-coated wire (color tone: red). Table 1 shows the results.

Example 2 A 2.5 mmφ original wire obtained by brightly annealing and softening a stainless steel wire for spring at 1150 ° C. was used to carry out the same two-layer plating and wire drawing as in Example 1 and JIS G4314. Stainless steel wire for spring
After obtaining a wire corresponding to 1 mmφ of WPB strength level, it was formed into a coil spring similar to that of Example 1, heat-treated, and subjected to the same test. Also, as a comparative example, 1mm from the 2.5mmφ original wire
A test was conducted on a bare wire obtained by wire drawing to φ. The results are shown in Table 2.

As can be seen from the results of Tables 1 and 2, when the plating thickness is 2 to 25 μm, the tensile strength and the twist value characteristics,
Both the fatigue strength and the corrosion resistance are good as a spring wire. On the other hand, when the thickness of the plating layer is 30 μm, the fatigue strength is markedly reduced, which is not practical. It can be said that the polyester coated wire is excellent in terms of corrosion resistance.

(Embodiment 3) In the 1 mmφ element wire of Embodiment 1, the total plating thickness after wire drawing is 2
Instead of μm, 5 μm was made, and this was molded into a coil spring and heat-treated to examine the color development. As in Example 1, Zn in the alloy plating layer was adjusted to 0, 5, 30, 45, 50.
% Was changed to 5 types. As can be seen from Table 3, if the plating thickness ratio of the Zn layer in the two-layer plating is adjusted so that the amount of Zn in the alloy plating layer is 5 to 45%, the color tone changes remarkably due to the heat treatment. Made by steel
The spring can be surely identified. In addition, the present invention is advantageous because the resin coating causes surface deterioration such as galling during molding, discoloration, and welding. Also in the case of the coil spring (strand wire: stainless steel wire) of Example 2, one in which the plating thickness ratio of the Zn layer in the two-layer plating was adjusted so that the Zn content was 5 to 45% as described above, The color tone changed as described above.

[0030]

Since the present invention is configured as described above, it is possible to easily identify the material or size of the material of the steel spring by coloring the plating layer during the spring manufacturing process. , The surface of the steel spring is given a beautiful color tone, and the spring characteristics are fixed to the steel spring.
Without causing degradation of the organic characteristics, but rather it is possible to achieve a remarkable effect of improving the corrosion resistance is extremely useful industrially.

It goes without saying that the present invention is not limited to coil springs and can be applied to spring materials (forming materials, torsion springs, leaf springs, etc.) or similar materials that are subjected to low temperature annealing after molding.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a relationship between a heating time and a heating temperature of a Cu—Zn plating layer on the surface of a spring molded product and a color tone change.

FIG. 2 is an explanatory diagram showing a relationship between a Zn content in a Cu—Zn plating layer on the surface of a spring molded product and a color tone.

FIG. 3 is an explanatory diagram showing the relationship between the Zn content in the Cu—Zn plating layer on the surface of the spring molded product, the plating layer thickness, and the red rust occurrence time.

FIG. 4 is an explanatory diagram showing a relationship between a Zn content in a Cu—Zn plating layer on the surface of a spring wire and a plating layer thickness, and a Hunter type rotary bending fatigue strength.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirofumi Ueki 10-1 Nakahama-cho, Amagasaki-shi, Hyogo Within Shinko Steel Wire Industrial Co., Ltd. (56) Reference JP-A-54-26931 (JP, A) JP-A-SHO 61-109623 (JP, A) JP 62-47497 (JP, A)

Claims (6)

[Claims] 1. Spring material processing and spring forming processing are performed.
On the surface of the core made of steel material for springs, the lower layer is Cu and the upper layer is
Made of steel with Cu-Zn plating layer whose coating layer is Zn as a coating layer
This Cu-Zn plating layer is formed on the spring and the final plating
The thickness is 2 to 25 μm, the thickness of the Zn layer with respect to the total thickness of the plating.
Low temperature baking performed after the spring forming process with a ratio of 5 to 10%
With blunt heat treatment, alloyed by diffusion and copper red
Be formed on a colored Cu-Zn alloy plating layer that develops a color
A colored steel spring that makes it easy to distinguish between different products. 2. Spring material processing and spring forming processing are performed.
On the surface of the core made of steel material for springs, the lower layer is Cu and the upper layer is
Made of steel with Cu-Zn plating layer whose coating layer is Zn as a coating layer
This Cu-Zn plating layer is formed on the spring and the final plating
The thickness is 2 to 25 μm, the thickness of the Zn layer with respect to the total thickness of the plating.
The ratio is 10 to 45%, and low temperature baking is performed after the spring forming process.
Alloyed by diffusion due to blunt heat treatment, and golden
Be formed on a colored Cu-Zn alloy plating layer that develops a color
A colored steel spring that makes it easy to distinguish between different products. 3. The lower layer is Cu and the upper layer is on the surface of the spring steel material.
2 layer plating consisting of Zn, Zn layer to the total thickness of the plating layer
The thickness ratio is 5 to 10%, then the spring material
So that the final plating total thickness is 2 to 25 μm
The prepared product is molded into a spring, and then the molded product is
Under low temperature annealing condition of 250 ℃ ・ 4 minutes or more to 400 ℃ ・ 2 minutes or more
When heated, the Cu-Zn plated layer is alloyed by diffusion,
, Copper red color is formed to form a colored Cu-Zn alloy plating layer
Colored steel that is easy to distinguish between different products
Manufacturing method of spring. 4. The lower layer is Cu and the upper layer is on the surface of the spring steel material.
2 layer plating consisting of Zn, Zn layer to the total thickness of the plating layer
The thickness ratio is 10 to 45%, and then the spring material
So that the final plating total thickness is 2 to 25 μm
The prepared product is molded into a spring, and then the molded product is
Under low temperature annealing condition of 250 ℃ ・ 4 minutes or more to 400 ℃ ・ 2 minutes or more
When heated, the Cu-Zn plated layer is alloyed by diffusion,
The gold -colored Cu-Zn alloy plating layer
Colored steel that is easy to distinguish between different products
Manufacturing method of spring. 5. The heating and holding time in the low temperature annealing is as follows.
The time t satisfying the formula is set to a time t.
A method for manufacturing a spring made of colored steel, which allows easy discrimination between different kinds of products. logt ≧ 1.193− 2.386 × 10 ⁻³ T …… Equation where T is the heating temperature in low temperature annealing
(° C.) and t indicate heating holding time (min.). 6. A hard steel wire, a piano wire or a spring steel material.
Use any of stainless steel wire for spring
Made of colored steel that makes it easy to distinguish between different products described in item 3, 4 or 5.
Spring manufacturing method.