Transactions of Japan Society of Spring Engineers

Development of Stainless Steel Wire for Spring having Excellent Size Stabilty at Tempering Treatment

Masaru KODAMA, Hiroichi IOKA, Yukio YAMAOKA

1992 Volume 1992 Issue 37 Pages 1-6
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.1

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In contrast with SUS304, hard drawn high carbon steel wires and a piano wires which show a great dimensional change after a low temperature tempering tretment, it has been cleared that a coil spring and a forming product made of a stainless steel wire having a two phase structure mixed with approximately equivalent quantities of α and γ show a very slight dimensional change which was an unknown property until now. It is considered that this characteristics was caused by different residual stresses attributing to the fact that neighboring α and γ have tension and compression each other.
This new spring wire has characteristics such that yield ratio, young's modulus, the number of torsion and fatigue limit are higher than SUS304 and corrosion resistance is also superior to it.

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Characteristics of Cu-Ni-Sn Alloys for Springs and Connectors

Mikio NISHIHATA, Shigeru OHYAMA, Akira SUGAWARA

1992 Volume 1992 Issue 37 Pages 7-13
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.7

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In order to correspond to recent developement in highly integrated circuit and miniaturized electronic equipment, copper alloys are required to be strong and have high electrical conductivity.
To cope with this situation, we have perfected an invention of high performance copper alloy for springs and connectors.
The nominal composition of this alloy is Cu-1.0Ni-0.90Sn-0.06P. Specimens of this alloy can be produced on a factory scale. Typical properties of this alloy are as follows:
(1) Mechanical properties: tensile strength; 570MPa, spring limit value; 477MPa, fatigue strength; 255MPa. Electrical conductivity is 38.1% IACS. This alloy has a good balance between strength and electrical conductivity.
(2) This alloy has high resistance to stress relaxation at 393K and 423K.
(3) This alloy exhibits high reliability of plating and solderability and has low contact resistance after heating.
(4) This alloy has high resistance to stress corrosion cracking in an ammoniac atmosphere.
(5) This alloy has good formability in the R/t=0.5 bending test.

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Effect of Non-Metallic Inclusions on Rotating Bending Fatigue Properties of Spring Steels

Kenji KANAZAWA, Takayuki ABE

1992 Volume 1992 Issue 37 Pages 15-23
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.15

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Rotating bending high-cycle fatigue properties of spring steels SUP7, SUP9A, and SUP12 are discussed from viewpoints of effects of inclusions on fatigue crack initiation and on relationship between fatigue strength and hardness. The conclusions obtained are as follows:
(1) The relationship between fatigue strength σ_wb at 10⁸ cycles in MPa and Vickers hardness HV can be obtained as σ_wb=1.71HV for materials where fatigue fracture occurs independently of inclusions, with the hardness larger than 400HV as well as with the hardness less than 400HV.
(2) Stage I cracks were observed for some directions from boundary between the inclusion and matrix, when fish-eye pattern was formed.
(3) The upper value of σ_wb/HV is 1.71 and the value decreases with increasing the weighted value of inclusions with increasing hardness. The harder the materials, the smaller inclusions can become crack initiation site.
(4) The estimation curves of the relationship between fatigue strength at 10⁸ cycles and Vickers hardness are proposed by fracture mechanics approach. Estimation of representative crack length √A including not only inclusion itself but also region of Stage I cracks from the inclusion is necessary to understand the difference between the experimental data and the estimation curves.

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Affection of the Hydrogen Embrittlement in Helical Coil Spring processed by the Cationic Electro-Deposited Coating

Katsuyuki NISHIOKA, Yasuo SATOH

1992 Volume 1992 Issue 37 Pages 25-30
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.25

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In order to meet with the requirement of automotive mass saving, high-strengthened helical coil spring has been increasing, so the improvement on corrosive resistance of coating becomes more important.
Although one of the most popular coating methods of helical coil springs is the anionic electro-deposited coating, it would be effective to change to the cationic electro-deposited coating, to obtain higher corrosive resistance.
However, while the coated material is anode in the anionic electro-deposited process, it is cathode in the cationic electro-deposited process like in the electro-plating.
Accordingly, in the cationic electro-deposition process, hydrogen gas is generated by the electrolysis of water at the surface of the coated material, so it has been considered that the coated material might possibly cause the hydrogen embrittlement.
This paper shows some experimental results for the helical coil springs coated by the cationic electro-deposited process. It is realized that they does not occlude the hydrogen gas and does not show any hydrogen embrittlement, as results of measuring the hydrogen gas by the several methods, the slow bending fracture test, and the delayed fracture test by the helical coil springs.

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An Isoparametric Plane-Element for Curved Beam

Application to Spiral Springs

Masayoshi SHIMOSEKI, Heiichi FUJINUMA

1992 Volume 1992 Issue 37 Pages 31-37
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.31

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Among various kinds of mechanical parts, there is no other element that is characterized by a large elastic deformation as the spring. With parts featuring such large elastic deformation, the treatment of its geometrical nonlinearity stands out as a most vital matter, for which it will be important to express the deformed shape precisely.
In this context, when analyzing springs by the finite element method (FEM), the use of a high-order isoparametric element appears appropriate, so we developed such an element for curved and twisted beams.
But there are many kinds of springs which can be treated as two dimensional problem. Naturally, it would be irrational to solve two dimensional problems in three dimensions.
This report deals with a high-order isoparametric element, limiting our discussion to the bending of beams having only plane curvature. The fundamental thought is based on the theory described in Ref. 1) in which the curvature and the cross-sectional size are variable in one element, so this method may be applicable to long tapered beams.
As an example, we apply the element to spiral springs, and introduce an up-dated Lagrange method to solve geometrically non-linear problems.

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Analysis of Leaf Springs using Finite Element Method with a Joint Element

Tosio HAMANO, Masanobu ITOH

1992 Volume 1992 Issue 37 Pages 39-46
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.39

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Riding quality of a vechicle equipped with the leaf suspension is closely associated with a spring rate of the leaf spring and so on. In this worke we examine the analytical properties of the leaf spring, in consideration of a contact between the plates. For a detailed analysis of springrates and deformations in the leaf spring, we have developed a computer program using Finite Element Method (FEM) including a joint element.

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Displacement and Stress Analysis of Wire Spring Composed of Circular Arc and Straight Line

Nobuyoshi MORITA, Kazuo ITO, Takao TORII, Yasuharu TSUCHIYA

1992 Volume 1992 Issue 37 Pages 47-51
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.47

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This paper deals with a wire spring whose shape consists of a random combination of circular arcs and straight lines. When a displacement of the end of spring is given, the displacement, the stress of all parts of the spring and the spring constant are obtained by two analytical methods as follows:
(1) Algebraical analysis: The method of applying Castigliano's theorem
(2) Numerical analysis: The method of applying transfer matrix
The method (2) is applied to the spring used as a part of Dot-printer, then the optimum shape to extend its life is shown. It is confirmed by the endurance test that the life of this new spring is beyond four times longer than that of the former spring.

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The Development of New Type Almen Strip for Measurement of Peening Intensity on Hard Shot Peening

Yoshihiro WATANABE, Norihiko HASEGAWA, Kunio NAMIKI, Atsumi HATANO

1992 Volume 1992 Issue 37 Pages 53-57
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.53

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As the fatigue strength of high hardness materials is mainly ruled by residual stress, it is essential to give compressive residual stress on surface layer to enhance the fatigue durability. For this reason, “hard shot peenig” characterized by its larger shot injecting energy with arc height higher than 0.6mmA has become of major interest lately. This process leads to an increase in fatigue strength by 25% compared to conventional peening process. Here, the arc height indicating peening intensity is ordinary measured by Almen strip A type, hardness of which is HRC 44 to 50. However, in hard shot peening, it has been pointed out that this strip is not proper as an index of peening effect, because the arc height measured by A strip is not in good correspondence to surface residual stress. Based on this background, the new type strip suitable for hard shot peening, conventional C type strip and high hard trial strip with hardness of HRC 60 were studied. Using these strips, the relation between residual stress and arc height measured by these strips were investigated. And it was concluded that the arc height measured by high hard trial strip was in good agreement with the maximum compressive stress and the magnitude of stressed layer.

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An Analysis of Load, Stress and Deflection in Nakamura-Type Rotating-bending Fatigue Test

Michihiko AYADA, Noritoshi TAKAMURA

1992 Volume 1992 Issue 37 Pages 59-64
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.59

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Nakamura-type rotating-bending fatigue test has been widely used for the evaluation of the fatigue strength of wire, because of its simplicity and rapidity.
The linear analytical solution obtained by the small deflection theory, has been applied to this test. Although this solution does not show any discrepancy when the load, stress and deflection are relatively small, there are some discrepancy when they become large in order to evaluate the fatigue characteristic of high strength steel wire.
Namely, if we set the weight by using this linear solution, the stress and deflection are underestimated compared with the true values. On the other hand, if we set the deflection by using this linear solution, the stress and load are overestimated compared with the true values.
These cases should be taken the so-called large deflection theory into consideration.
In this paper, we propose the solution based on the energy minimizing theory. This solution can explain the non-linear characteristic between the load, stress and deflection. The calculated values show good agreements with the experimental values, even though this solution is derived from the approximated method.

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Application of Very Thin Plate Springs for Precise Robot-Automated Jumpering Systems

Shigeru UMEMURA, Tsuneo KANAI, Yasuo KUMAKURA, Shuichiro INAGAKI

1992 Volume 1992 Issue 37 Pages 65-70
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.65

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High-density pin-board-matrix switches composed of matrix boards and connecting pin are designed to provide the cross-connecting function of an automated main distributing frame (MDF) system. The cross-connection is performed by inserting a connecting pin into a through hole on the matrix board.
A small automated MDF system is made possible by using simultaneous connection of a paired line with a single connection pin. The low normal contact force design, small insulation spacing design between the neighboring conductor patterns, and durability investigation of very thin plate springs gives a through hole pitch of 1.5mm and a connecting pin diameter of about 1mm.
Evaluation of the contact characteristics and electrical characteristics of the matrix boards and connecting pins satisfy the design requirements and show that matrix boards and connecting pins are applicable for the automated MDF systems.

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Examination for Characterization of Very Thin Plate Spring Materials

The Committee for Characterization of Spring Mater

1992 Volume 1992 Issue 37 Pages 71-87
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.71

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In recent years, the progresses of small-sized, lightened, thin-sized and malti-functioned movement are remarkable in electronic instruments. Therefore, springs used in those instruments are more thin and small-sized. And uniformity of their mechanical properties and dimensional tolerances are required more and more.
The Committee for Characterization of Spring Materials in Electronic Use had started in April, 1986. In the Committee, concerted examinations on tensile test, micro-vickers hardness test, fatigue test and bending spring limit test of very thin plate springs have been carried out. In this report, some problems of those tests are mentioned, and improved testing methods are suggested.

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Directions for High Fatigue Performances of Springs under Severe Stress Conditions

Committee for Endurance Properties of Springs

1992 Volume 1992 Issue 37 Pages 89-116
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.89

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High fatigue performances under severe stress conditions are desired for springs. Recently, this tendency is getting stronger than ever. Problems in evaluation methods of fatigue properties of springs and the present situations of advanced technologies to obtain high fatigue performances were discussed in this committee, concerning to manufacturing processes of spring materials and springs.
This report describes the results of the activities of the Committee and consists of following items:
1. Purpose of the committee
2. Fatigue of springs
3. Directions for high fatigue performances in relation to manufacturing prosess of materials for springs
4. Directions for high fatigue performances in relation to manufacturing prosess of springs
5. Fatigue fracture mechanism
6. Summary

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Trends of Spring Technology Material

T. YAMAMOTO, T. KUNII, H. OGITA

1992 Volume 1992 Issue 37 Pages 117-118
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.117

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Trends of Spring Technology Design & Performance

K. CHISHIMA, T. KUNOH

1992 Volume 1992 Issue 37 Pages 118-119
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.118

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Trends of Spring Technology Manufacturing, Testing, Inspection

H. TOSHINO, M. SAKAMOTO

1992 Volume 1992 Issue 37 Pages 119-121
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.119

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Trends of Spring Technology Standard

N. MIYAGAWA, T. OZONE, J. MASUDA

1992 Volume 1992 Issue 37 Pages 121-123
Published: March 31, 1992
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1992.121

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