Transactions of Japan Society of Spring Engineers

Development of a New Light-Weight Suspension Coil Spring Steel

Osamu NAKANO, Takayuki SAKAKIBARA, Atsushi SUGIMOTO, Shigeru YASUDA, W ...

1994 Volume 1994 Issue 39 Pages 1-5
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.1

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This newly developed herical spring steel can be used at stress level up to 1300MPa. The material is composed of Fe-C-Si-Mn-Ni-Cr-Mo-V alloy. Its strength-toughness balance was greatly superior to that of conventional spring steels. Additional elements were optimized by experimental design procedures. Impact value of the developed steel was twice as large as that of the conventional steel at the high hardness level.
This spring achieves a weight reduction of at least 30% and, possibly, to 40%.

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A Comprehensive Evaluation of Factors Influencing the Fatigue Strength of Spring Steels (Nonmetallic Inclusions, Shot Peening, Decarburized Layer and Small Surface Pits)

Yukitaka MURAKAMI, Motokazu KOBAYASHI, Taizo MAKINO, Toshiyuki TORIYAM ...

1994 Volume 1994 Issue 39 Pages 7-16
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.7

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An experiment was undertaken to verify the possibility of applying shot peening and decarburized layer, that influences the fatigue strength of automotive suspension spring steels (SUP9/SUP10M), to a predictive equation for fatigue strength proposed by Murakami et al. which uses the steel's matrix Vickers hardness, square roots of projection area of nonmetallic inclusions and surface micro pits, and stress retios as such factors. The purpose of the experiment is to determine the possibility to establish an equation that predicts the fatigue strength of the steels by comprehensive evaluation of six above-said factors.
The experimental results are as follows:
1) Two factors, shot peening and decarburization, can be applied to the equation as a mean stress and hardness, respectively. As the results the equation can accomplish a comprehensive evalution of six factors to predict the fatigue strength of spring steels.
2) The lower limit of the fatigue strength scattering can be evaluated by substituting to the equation of the square root max. of the maximum nonmetallic inclusion dimensions predicted by statistics of extremes.

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Effects of Non-Metallic Inclusions on Uniaxial and Reversed Torsion Fatigue Properties of Spring Steels

Takayuki ABE, Kenji KANAZAWA

1994 Volume 1994 Issue 39 Pages 17-26
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.17

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Uniaxial and reversed torsion fatigue properties of spring steels SUP7, SUP9A and SUP12 are discussed from viewpoints of effects of inclusions on relationship between fatigue strength and hardness, comparing with the results obtained previously for rotating bending fatigue properties.
The conclusions obtained are as follows:
(1) As for uniaxial fatigue under stress ratios of -1 and 0, an inclusion was observed at the crack initiation site and the fatigue strength were smaller than that estimated from hardness.
(2) Uniaxial fatigue strength under a stress ratio of -1 was smaller than rotating bending fatigue strength, as the frequency of existence of nonmetallic inclusions is high under a condition of uniform stress distribution.
(3) As for reversed torsion fatigue, nevertheless no inclusion was observed at the crack initiation site, the fatigue strength were smaller than that estimated from hardness.
(4) Fine correlation between weighted value of inclusions and fatigue strength was not observed for uniaxial and reversed torsion fatigue strength normalized by Vickers hardness.
(5) The estimation curves of the relationship between fatigue strength and Vickers hardness and fatigue limit diagrams taking initial crack size as a parameter are proposed by using fracture mechanics approach.

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Strength Characteristics of Si₃N₄ for Heat Resisting Spring at Elevated Temperature

Mincheol CHU, Shigemi SATO, Buan KIM, Kotoji ANDO

1994 Volume 1994 Issue 39 Pages 27-31
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.27

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The static fatigue test have been carried out at 1200°C in air by useing plain and surface cracked Si₃N₄ bend specimen. This Si₃N₄ was developed for heat resisting spring. The dependence of fracture stress on the crack length is examined at room temperature and elevated temperature of 1100°C and 1200°C, and the applicability of the process zone size failure criterion for silicon nitride ceramics is studied. The results showed that the process zone size failure criterion is useful for evaluating crack length problems both at room and at elevated temperature.
In this experiment, high fracture toughness has been obtained by crack deflection and bridging of rod-like grains. And high fracture strength was also obtained because of well controlled microstructure of the Si₃N₄.
The cracked specimen with surface crack length of 650μm has showed static fatigue limit of 120MPa, and the time is 10⁷ sec which is longer than the time reported. As a result of these static and static fatigue test, this Si₃N₄ is assumed to be useful material for heat resisting spring.

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An Isoparametric Element for Curved and Twisted Beam with Rectangular Section

Masayoshi SHIMOSEKI, Heiichi FUJINUMA, Kanna CHINO

1994 Volume 1994 Issue 39 Pages 33-39
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.33

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This paper describes a finite element for beam of arbitrary centroid shape with rectangular section. In case of beam with arbitrary centroid shape, it is also possible to adopt the same warping function of Saint-Venant' torsion as cylindrical beam with same cross section. As well known, the warping function of rectangular section is expressed by Fourier expanison.
Including this into displacement functions, we formulate the elment stiffness matrix.
In order to make sure the sufficency of our formuration, we carry out the numerical calculations in two typical cases i.e. helical spring with rectangular section and wave-spring.
The experimental results have shown that our formulation is applicable.

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Reliability Design of Helical Compression Spring

Li CHEN

1994 Volume 1994 Issue 39 Pages 41-45
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.41

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Reliability design is a developing domain of the science and technology. At present, the reliability engineering in spring manufacture is only on the stage of reliability testing and there are few documents concerning research in this field. After many years' reliability study, the author has deduced the reliability design formula for helical compression springs by the intervene theory of stress-strength distribution. This is the first time that the shot-peening and warm setting are introduced in the design parameters affecting the life of products. The author has also specified the relations between reliability and material strength of the products and the manufacturing process level. It will establish the basis of the system of spring reliability design theory.

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Characteristics of Gas-Spring

Effect of Temperature and Loading Speed

Takeyoshi SHINBORI, Chiharu UMETSU, Shinsuke MORITA, Hiroshi MIZUKAMI

1994 Volume 1994 Issue 39 Pages 47-51
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.47

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It is well-known that Gas spring is applied to the suspension of vehicle and the die cushion for pressing machine. The calculation of Gas spring characteristic is usually conducted by using polytropic index, which is determined by assuming the change of compressing or expanding time and pressure to be polytropic change. However, since there are some hysteresis caused by heat-transfer, the calculated values has not had good correlation with actual values.
In this studies, refering to experimental studies for the heat-transfer of gas-charged accumulator, the dynamic characteristic of Gas spring was calculated by using a thermal time constant obtained experimentally. It was found that the calculated values show good agreement with the experimental values and this method be effective for the calculation of Gas spring characteristic.

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Working Characteristics of Cold Coiled Helical Compression Springs with Synchronous Cutting System

Effect of Improved Coil Holder

Takamitsu IMAI, Keisuke SASAKI, Tomonori KAMIYAMA, Kazunori TSUSHIMA, ...

1994 Volume 1994 Issue 39 Pages 53-59
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.53

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As the result of improving the coil holder forced to revolve the coil, the working characteristics of the cold coiled helical compression spring were improved in comparison with the unimproved coil holder. The suitable range of the cut-off wheel for cutting spread, too.
It was also cleared the working characteristics of the manufactured spring of SWOSC-V (JIS G 3566). The working characteristics of SWOSC-V spring became higher than that of SWC (JIS G 3521).

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Layout of Coiling Tools and Inclination of Elliptic Wire Cross Section in Coiling

Masato GOHDA, Shunichi KUDOH, Takahiko KUNOH, Kazunori TSUSHIMA

1994 Volume 1994 Issue 39 Pages 61-66
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.61

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In order to study relations between a specific layout of coiling tools and inclination of ovate wire cross section in helical springs, experiments were made on an elliptic wire with a two-point coiling machine. As a result of the experimental analysis, layout of the tools have been made clear to keep the torsion within a small range.

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Study on High-Strength Oil-Tempered Chromium-Silicon Alloy Steel Wire for Fine-Size Springs

Research Commitee on Durability of High-Strength, Fine-size Spring W ...

1994 Volume 1994 Issue 39 Pages 67-100
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.67

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At a standardization of fine size oil-tempered chromiun-silicon alloy steel wire in Japanese Industrial Standard (JIS), there is a strong demand to match contents of JIS to equivalent ISO. However, the high-strength wire which specified in ISO has never been used in the Japanese market. This joint study investigated mechanical properties, sag resistance and fatigue life of three levels of high-strength wire whose tensile strength were adjusted between upper-end of ISO and JIS range.
From the result of our study, it became clear that strengthening through lowering tempering temperature at oil-temper process is not effective for the improvement of sag resistance and fatigue life. Furthermore, it was indicated that strengthening combining with change in chemical composition or shot peening can be effective for the improvement.

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Study on Oil-Tempered Chromium-Silicon-Alloy High-Strength Steel Wire for Suspension Springs

Research Committee on Durability of High-Strength, Suspension Spring ...

1994 Volume 1994 Issue 39 Pages 101-130
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.101

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Suspension springs are one of the automotive parts of which weight reduction is looked forward to and consequently demand is strong for higher strength materials. Therefore, the present joint study not only investigated and evaluated the currently available highstrength steel wires but also tried to recognize the problems involved and countermeasures required in increasing the strength of materials.
From the results of our study, it was clarified that higher strength of materials was effective in improving the sag resistance of springs. However, it was also indicated necessary to consider such processes as shot peening in the production of springs to ensure satisfactory durability.
Regarding the formability of steel wire which is likely to become an important issue in the future, a notch-bending test was introduced as one of the useful indexes to evaluate the formability of materials.

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Trends of Spring Technology Material Design, Performance and Application

J. MASUDA, K. CHISHIMA

1994 Volume 1994 Issue 39 Pages 131a-133
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.131a

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Trends of Spring Technology Material Material

T. YAMAMOTO, T. OGITA

1994 Volume 1994 Issue 39 Pages 131
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.131

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Trends of Spring Technology Material Manufacturing, Testing and Inspection

T. KUNII, M. SAKAMOTO

1994 Volume 1994 Issue 39 Pages 133-134
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.133

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Trends of Spring Technology Material Standard

T. OZONE, K. SUZUKI

1994 Volume 1994 Issue 39 Pages 135-137
Published: March 31, 1994
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1994.135

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