Shoji Haizuka

Study on tooth surface strength of spur gears-Part I : Experimental procedure and determination of tooth surface strength

For a long time, the tooth surface strength of gears has been investigated under various conditions. At first research concerning tooth surface strength focused mainly on gears of lower hardness. Because the practical usage of gears with high hardness has recently increased considerably, a more fundamental research on tooth surface strength of gears with high hardness is required to increase the load carrying capacity of gears. Recently, many basic studies on the tooth surface strength of gears were carried out in order to improve tooth surface strength. But further research on tooth surface strength is still needed. In view of this present state of research, the authors developed a project to carry out preparatory experiments mainly on the following topics: (1) tooth surface strength using various lubricating oils, (2) tooth surface strength under various effective depths of case-hardening of tooth surfaces, (3) tooth surface strength using test gears with shot peening treatment, (4) tooth surface streng...

Influence of Oil Viscosity, Chemical Oil Structure, and Chemical Additives on Friction Loss of Spur Gears (Concerning the Influence of Synthetic Oil and Mineral Oil)

The friction loss of gears and its quantitative estimation are important problems because of their relevance to energy conservation and load-carrying capacity. Recent research results do not provide satisfactory estimates of friction loss of spur gears. Therefore, the authors carried out experiments to study the influences of lubricating oil viscosity and additives, as well as base oil type and load and rotational speed on friction loss of spur gears

Study on tooth surface strength of spur gears-Part II : Special attention on effects of lubricating oil, material and tooth surface heat treatment

For several decades, intensive research of tooth surface strength of gears has been undertaken to achieve better gear design. Because the practical usage of gears with high hardness has recently increased considerably, a more fundamental research on tooth surface strength of gears with high hardness is required to increase the load-carrying capacity of gears. In view of this present state of research, the authors carried out many experiments in depth mainly on the following topics: (1) tooth surface strength using various lubricating oils in various conditions, (2) tooth surface strength under various effective depths of case-hardening of tooth surfaces, (3) tooth surface strength using test gears with shot peening treatment, and (4) tooth surface strength under various tooth surface treatments (through hardening and nitriding), and (5) tooth surface strength as a function of tooth hardness. Following the description of the authors experimental frame-work laid down in Part I, they thoroughly tested it and...

Study on Load Carrying Characteristics of Crossed Helical Gears (Special Focus on Scuffing Strength, Wear and Friction Loss)

Crossed helical gears fail mainly by scuffing. Power transmission is low, because the Hertzian pressure in the small elliptic contact area is very high, and the sliding velocity between two contacting tooth surfaces is very high compared with other kind of gears. However, crossed helical gears have important advantages, since they are easy to produce and their engagement is not influenced by mounting errors in center distance or shaft angle. This study presents some new ways of improving the load carrying capacity of crossed helical gears. The influence of lubricating oil, tooth surface treatment, and tooth form on the limiting load for scuffing was studied experimentally. The results were summarized and formulas were established in view of practical design.

Study of Influence of Lubricating Oil and Tooth Height on Friction Characteristics of Helical Gears

It is of utmost importance to know the friction loss of helical gears because they are produced quite widely used. However, basic research, e. g., load carrying characteristics of helical gears and friction loss, is extremely scarce. In this paper the authors focused on the influence of the kind of lubricating oil on the friction loss of helical gears. Further they dealt with the influence of height of teeth on friction loss of helical gears. The authors carried out experiments to study the influence of lubricating oil viscosity, additive, and base oil type as well as rotational speed on friction loss of helical gears. Not only mineral oils but also synthetic oils were used as base oils, e. g., paraffin, poly-α-olefin, and polyglycol type oils. As additives the authors used EP additive and ZnDTP. Further they investigated the influence of tooth height on friction loss. The experimental results gained make it possible to drastically reduce friction loss of helical gears.

Influences of surface roughness and viscosity of lubricating oils upon limiting load for scoring of spur gears.

There are many factors, which have effects upon the load carrying characteristics of the spur gears. The surface roughness of tooth and viscosity of lubricating oils, furthermore the concentration of additives are the very important factors for the determining the load carrying characteristics of the spur gears. As main factors for determining the load carrying characteristics, the limiting load for scoring and the specific wear were chosen here. The roughness of the tooth surface for our experiments was in the range of 1.1∼7.5 μm. The kinematic viscosity of the lubricating oil for the experiments was 2.9∼4.0 ×10-6 m2/s at 90°C. The experimental equipment was the FZG spur gear testing machine and the test gears had also the original tooth form of FZG test gears but our test gears were specially crowned in direction of tooth trace and effective width was reduced to b=8 mm in order to get the higher Hertzian pressure. This tooth width is very narrow in comparison with the original one.

Studies on limiting load for scoring and frictional loss of hypoid gears (Mainly effects of surface treatments and lubricating oils)

諸元・工作方式が異なった3種類のハイボイドギヤのスコーリング限界荷重を比較した.次に表面処理の違いがハイポイドギヤのスコーリング限界荷重へ及ぼす影響を調べ,平歯車と2円筒試験の実験結果と比較したところ,表面処理がスコーリング限界荷重へ及ぼす影響は,接触条件により大きく変わることがわかった.またハイポイドギヤの摩擦係数はその種類によらず,すべり速度の関数として表されることがわかり,その実験式を求めた.

Research of frictional loss,temperature rise and critical scouring load of spur gear.

FZG平歯車試験装置を用いて,一般に使用されている鉱物系潤滑油を使い,歯のかみあい損失率,歯の温度上昇およびスコーリング限界荷重を求めた.試験歯車は,モジュールを2より6まで変化させ,転位係数も,極端に一方に転位したものから標準歯車の場合に至るまで大きく変化させた.そしてスコーリング限界荷重,摩擦損失率および歯の温度上昇のそれぞれを求める式およびこれらの相互関係を明らかにした.

Effects of Oil Viscosity and Anti-wear Agent on Load Carrying Characteristics of Hypoid Gears : Mainly on Limiting Load for Scoring and Power Loss

Experiments on the load carrying characteristics of hypoid gears with various oil viscosities and concentrations of anti-wear agent were carried out. As the result, it was found that there are some general tendencies about the limiting load for scoring and friction loss of the hypoid gears. The limiting load for scoring is quite dependent upon the viscosity of base oil and the concentration of anti-wear agent but the frictional loss mainly dependent upon only the oil viscosity but independent upon the concentration of anti-wear agent. Furthermore the friction loss of the hypoid gears was compared with that of the spur gears.