有浦 泰常

ホブ切り過渡現象の観察と切りくず生成機構の解明 : 第2報,ホブ切り過程における切りくず生成と挙動(機械要素,潤滑,工作,生産管理など)

The transient phenomenon of chip generations and behavior in hobbing are investigated by using high-speed video camera. The chip behavior in gear finish hobbing process and in hobbing of a special workpiece with one tooth space is investigated. New visual findings such as the chip interference on rake surface and the condition of contact with the work surface can be obtained. In the case of dry cutting with high-speed steel flytool having non-coated rake face, the flytool cuts the workpiece frequently as attaching on the rake face with the chip before one revolution. The newly produced chip push out the old attached chip and flies away. The now of chip is interfered strongly at the corner of cutting edge when both top and side cutting edges produces it at the same time, and flow out as changing the shape. Three chips attached on the rake face before next cutting are also observed.

大容量高周速まがり歯かさ歯車の動的挙動に関する研究 : 第2報, 動的特性の理論検討

To reduce the size of reduction gears of the large drainage pump and helicopter where large power is transmitted through crossed shafts, it is necessary to increase rotational speed and decrease transmitted torque and load. To know dynamic behavior of high speed bevel gear, the experiments were carried out where dynamic loads were measured. Also a spiral bevel gear set computer program has been developed that makes use of meshing dynamic loads and contact patterns. And then, the following results were obtained. (1) A power absorbing spiral bevel gear testing machine (18, 400 kw) which was designed by the developed program could be operated up to high line velocity (∼117m/s) (2) Analytical results of dynamic load agreed with the experimental results. It was Confirmed that the analytical method has practical accuracy and usefulness.

ホブ切り歯車の精度向上に関する研究 : 第6報, 各種誤差要因の影響を含む歯切り誤差の解析法及び実験検証

There are a lot of factors influencing hobbing accuracy because hobbing is intermittent cutting and its generating motion is complex. These factors are geometrical, kinematical, dynamic or cutting mechanismic, and the errors of a hobbed gear are usually dependent on the combined effect of the factors. On the other hand, it is not easy to exactly measure the errors of the generating motion between the hob and gear biank. For these reasons, it is difficult in general to determine the valid influencing factors and to decide on a method of improvement when an engineer is facing a problem with hobbing accuracy. In this paper, a developed analysis method, which can conveniently calculate the errors of a hobbed gear in three dimensions by the action of an individual or a combination of various influencing factors, is proposed. Some useful information for improving hobbing accuracy may be obtained by applying the method to comparing and analyzing the measured data with calculated ones. It is also confirmed that this method is valid because the calculated error curves are in good agreement with measured results.

中硬度歯車の面圧強さに関する基礎研究 : 第3報, 歯車対に硬さ差をつける意味に関する一考察

The effects of the combination of tooth flank hardness and tooth surface roughness on the surface durability of medium-hardness gears are examined by using a disk machine. The meaning to give difference of hardness between a pair of gears is investigated. In the case that the surface roughness is different between the contact surfaces with same initial hardness, the severe wear and pitting occur on the smooth surface. Because the tip of asperities on the rough surface hardens strongly due to the repetition of contact. Therefore it is necessary that the initial hardness of smooth surface is higher than that of rough one in the combination of different surface roughness. This means that the combination of hardness between a pair of pinion and gear should be determined by considering the condition of tooth surface finishing.

ホブ切り歯車の歯面形状に関する研究 : 第2報, 送り目とホブ切り誤差および歯形誤差との関連

The feed marks on the tooth surfaces of hobbed gears express the characteristics of the tooth surfaces very well, and are related closely to the errors of hobs and hobbing machines. In this paper, the formation mechanism of feed marks caused by the errors of hobs and hobbing machines is investigated, and the relationships between the errors and the feed marks in the tooth surface configurations shown in the first report are clarified. Moreover, the relations between the feed marks and calculated tooth profile errors are investigated. From those relationships, it is possible to estimate the errors of hobs and the hobbing machine by the feed marks of hobbed gears.

ホブ切り歯車の精度向上に関する研究 : 第4報,ホブの取付け偏心の調整による被削歯車歯形精度の向上

Recent studies showed that the tooth profile errors of hobbed gears were mainly caused by the geometrical error and eccentricity error and eccentricity of the hob under good cutting conditions. Because manufacturing a highly accurate hob is very difficult and maybe a highly accurate gear is not obtained even though a highly accurate hob is used, it is very important to investigate how to improve the actual meshing accuracy of the hob in the cutting process. In general, the meshing error of the edges caused by the hob eccentricity is nearly sinusoidal and also the geometrical errors often contain sinusoidal components. On the basis of these facts, this report proposes a method which makes both of the sinusoidal error components cancel each other out in order to obtain an accurately hobbed gear. The test results clearly show its usefulness to improve the tooth profile errors of the gears.

中硬度調質歯車の負荷能力に関する研究 : 第5報,歯面強さに及ぼす歯数比と粗さの影響

The surface durability of hardened and tempered gears (HB 340) having a gear ratio of u≠1 was investigated by using a power circulating-type gear testing machine. The test results reveal that the gear ratio has a great influence on surface durability in the case of gears with rough tooth surfaces, such as hobbed gears. The endurance limit of medium-hardness gears is summarized as follows : Under the condition of rough initial tooth surface, (i) Pmax 0.1 HB kgf/mm2 in the case where the gear ratio u is not unity, (ii) Pmax 0.2 HB kgf/mm2 in the case that u equals unity. But, if the initial tooth surface is very smooth, (iii) Pmax 0.3 HB kgf/mm2 regardless of the gear ratio. In conclusion, the tooth surface should be finished as smoothly as possible in order to obtain a high load-carrying capacity because the influence of roughness is more remarkable in conventional gears having a gear ratio of u≠1.

ホブ切り歯車の精度向上に関する研究 : 第2報,解析歯形誤差と実測歯形誤差の比較および誤差要因の検討

The causes of tooth profile errors in gear hobbing are investigated by comparing the computed tooth profile errors with the measured ones, for manufacturing accurate gears. Under various hobbing conditions, gears are cut and measured. Spheroidal graphite cast iron is used as hobbed test material because built-up edge hardly occurs. From these comparisons, it is found that the tooth profile errors are mainly caused by the geometrical errors and the eccentricity of the hob. The tooth profile errors caused by the dynamic errors of the hobbing process are very small under these conditions, though they are observed more or less in the case of helical gear hobbing. It is also confirmed that the calculating method of tooth profile error, which is reported in the 1st report, is useful in analyzing gear accuracy.

円筒歯車の加工と性能に関する研究 : 第1報,歯面強さ向上を目的とした仕上げホブの適用

Recent research indicates that tooth surface roughness has a significant influence on the surface durability of gears. In order to obtain smooth tooth surfaces economically, the authors have developed new finish-hobs, which have many numbers of gashes and a positive rake angle to control the occurrence of built-up edges. By applying these hobs to the finish-hobbing of medium-hardness gears(HB 340), the surface roughness is reduced to a half or a third compared with usually hobbed gears. The surface durability of finish-hobbed gears is investigated by using a power circulating-type gear testing machine. The relation between tooth surface roughness and pitting area ratio can be grasped quantitatively. And it is clear that these new finish-hobs are practical for obtaining a high load-carrying capacity of the gears.

ホブ切り歯車の精度向上に関する研究 : 第1報,歯形誤差形状の解析

Accurate gears are needed in order to obtain the high load carring capacity of gears. This study aims at manufacturing highly accurate gears by hobbing. In this report, a method for the calculation of tooth profile errors caused by geometrical hob errors such as profile errors of the hob tooth and the eccentricity of the hob is proposed. From the comparison of the calculated tooth profile errors with the measured ones in hobbing tests, it is found that the tooth profile errors generated by the geometrical errors and the eccentricity of the hob can be distinguished from those by the dynamic errors of the hobbing process, i.e. vibrations, built-up edges and so on. It is proved that the accuracy of this calculation method is sufficient to study the accuracy of hobbed gears.