The toroidal involute worm (TI worm) drive is composed of an involute gear and an worm generated by the involute gear surface, and it is of great advantages for power transmission. Because of the difficulty of grinding TI worm tooth surface, the TI worm drive has rarely been used. To solve this problem, an accurately turning method through the helix for the TI worm tooth surface is proposed. For this accurately turning method, mathematical models are developed, basic equations are derived and turning accuracy is analyzed. A nylon TI worm is turned and the red test of TI worm drive is checked. It is made clear that the proposed accurately turning method is correct and practicable. The study is expected to provide the theoretical and experimental foundation for the future explore the accurately hard turning of TI worm tooth surface.

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The manufacturing method of two spatial-orthogonal rotary axis linkage is usually used to cut

worm. However, the traditional processing method of roughing tooth groove depends on the special machine, specific tool, and its processing efficiency is lower. To avoid these defects, a processing method of the rough cutting worm on general NC lathe without C-axis functions was presented in the paper. Based on the forming principle of the worm and the traditional processing steps, the machining principle of the new approach was elaborated. Key techniques such as the shape of the blade, the contours of tooth groove, tool path loop and the variable lead of worm, etc. were discussed. Macro-program of the new method was programmed based on Fanuc oi mate-tc CNC system, and tooth groove of the worm were trial manufactured on general NC lathe. Addendum axial pitch and a normal tooth thickness of the trial model were measured. It is noted that measurement results can satisfy the technological requirement. In conclusion, the new processing method of roughing worm is feasible and efficient.

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To satisfy the requirements of high accuracy and high-loading capacity, a novel precision-power worm drive characterizes with backlash-adjustable and wear-compensable is demonstrated. This worm drive is consisted of an involute helical beveloid (IHB) gear and a toroidal involute (TI) worm generated by the IHB gear tooth surface, and the material of IHB gear is bearing steel, as well as the material of TI worm is structural steel. For this worm drive, mathematical model is developed, basic equations are derived, and tooth contact analysis (TCA) is simulated by computerized calculation examples. Theory of backlash-adjustable and wear-compensable of this worm drive is derived. The high-loading capacity of this novel worm drive is confirmed by the TCA and stress analysis. This study is expected to provide a theoretical foundation for the future industrial application of this novel backlash-adjustable and wear-compensable worm drive.

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Cutting teeth of a dual-cone double enveloping

worm wheel hob retain land surfaces with a certain width to increase the service life of the hob because this kind of hob cannot be re-sharpened. The land widths from the top to the root of all of the cutting teeth should be uniform so that all of them have the same cutting performance. However, the accuracy and the uniformity of the land width of the land surface of hob with spiral rake faces have not been studied till now. To solve this problem, this paper puts forward a method for designing the land surfaces of the hob with spiral rake faces and studies the accuracy and the uniformity. The spiral rake faces of the teeth of the hob are generated by a cylindrical surface. The offset surfaces of the spiral rake faces are obtained by offsetting the spiral rake faces along their normal vector directions with the offsetting distance equal to the land width. The rake faces and the offsetting surfaces intersect with the helical surfaces so the cutting edges and the land edges can be gotten, respectively. The land width of each cutting tooth is the distance between its cutting edge and its land edge. The results of a numerical example show that the calculated land widths on the pitch torus decrease firstly and then increase from one end to another end along the axial direction. The difference of the calculated land widths between the top and the root is larger at side teeth than that at middle teeth. The calculated land widths are slightly larger than the given one and all the calculated land widths change within a small range that can be ignored. Therefore, the method can keep the accuracy and the uniformity.

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The modification of the planar double-enveloping

worm gear drive can eliminate the phenomenon of the contact line cross and improve the transmission performance. In order to guide the selection of the type and the amount of modification, the equations of the contact zone and rear transition zone on the worm wheel surface are established. According to the position relationship between the contact zone and the rear transition zone on the axial plane and transverse plane, the changes in the tooth surface of the worm wheel obtained by different modification methods are obtained. The tooth surface changes obtained under different modification amounts are further summarized. The structure of the modified worm wheel is finally determined. For Type-II drive processed with the center distance modification, the curvature interference limit line on the surface of the worm wheel can be cut off by the last cutting edge of the hob. The larger the amount of the center distance modification value is, the deeper the depth into the rear transition zone is. Finally, the analysis results were verified by the hobbing experiment and the worm gear drive running test.

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To avoid the influence of small displacement of gear axes under load, the authors propose that all contact normals of a tooth surface should be at right angles to the direction of the small displacement induced at each contact point under load. On the basis of this state of surface normals, a few methods of tooth surface generation have been devised for realizing the concept. In this research, an worm gear was made using one of the generating methods, and tested experimentally. As a result, the validity of this designing concept was substantiated.

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The new precision transmission system-Anti-backlash roller enveloping

worm gears are now widely employed in many industrial sectors such as robot joint design, packaging production line, and CNC (computer numerical control) machine tools. Therefore, it is of great interest to have knowledge of their corresponding transmission principles that are seldom discussed in the literature. Using the theories of differential geometry and gear meshing, the objective of this paper is to analyze and compare meshing characteristics of anti-backlash single- and double-roller enveloping worm gears in terms of their transmission principle, engagement equation, induced normal curvature, lubrication angle, autorotation angle, entrainment velocity, helix angle, and distribution of contact curves. The major differences between these two roller enveloping worms are theoretically investigated in this work. Our results show that the anti-backlash single-roller enveloping worm (ASEHW) gears provide better performance with respect to gear meshing and transmission than the anti-backlash double-roller enveloping worm (ADEHW) gears. In addition, compared with the ADEHW gears, the ASEHW gears are easier to fabricate, install, and calibrate. However, the ADEHW gears are more auto-adjustable in eliminating gear backlash. Our study puts forward a theoretical background for futuristic design, application, and promotion of the anti-backlash roller enveloping worm gears.

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Authors reported theory of worm gearing whose worm is generated by high speed screw generating method, on previous report. CNC high speed worm generating machine has been developed according to the theory. And worm cutting test and performance test of worm gearing was made. The test results are as follows: (1) Newly developed machine has high speed cutting ability same as mach type screw generating apparatus. (2) Surface roughness of worm tooth surface generated by the CNC high speed worm generating machine has same order of roughness of screw surface cut by mach type screw generating apparatus. (3) worm gearing generated by the newly developed machine showed high efficiency and ran 1000 hours without trouble.

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In a high-speed impact, both projectile and target experience an extreme distortion. A simulation in Eulerian formulation is therefore favorized. Contact-impact with Lagragian meshes are also presented. Focused topics here are Lagrangian and Eulerian formulation of a continuum media, plasticity flow, material separation due to failure or penetration, contact algorithm, 1-point integrated elements for computational time performance.

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有限要素解析において, アワーグラスという不安定現象がある. それは, 一点積分法を用いて, 剛性マトリックスを計算する際に生じる. この不安定現象を制御するために, 色々な方法が提案されている. その一つであるD. Kosloff とG. A. Frazier らによって提案された方法は, 長方形要素の場合に, 最も有効であり, 簡単である. しかし, その方法は, 弾性問題に限られる. 本論文では, アワーグラス現象制御方法を如何に非線形解析に適用するかの詳細を示している. さらに, より正確な非線形応答を得るために, 修正した方法を提案している.

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The authors developed the new type worm gear of plastics involutes helical gear wheel. The theory, the calculation of the tooth contacts analysis for the prediction of the performance of the gear and the production method of the steel worm and the plastics wheel are reported. A set of the worm gears was manufactured. And the accuracy of the transmission was measured by the measuring machine for the angular transmission error (abbreviated to ATE) of the reducer invented by A. Horiuchi and others. The efficiency was tested by the power absorption type worm gear testing machine, designed and made by the authors. The efficiency of the worm gear was compared with the cylindrical worm gear of steel worm and plastics wormwheel whose dimensions was the same of the worm gear proposed in this report.

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  Foods and their related materials found in gastric contents or illegal industrial wastes sometimes play important roles in cases of murder, industrial and environmental crimes. Though the observation of starch by the light transmitted microscope has been frequently carried out for the forensic purpose, the shape of starch is sometimes diminished by putrefaction or digestion. Seed coats are considered to remain in their shapes against the operation of decomposition in comparison to starch and their textures may be preserved in such severe conditions. Nevertheless, detail examinations had not been carried out from the forensic point of view. For the forensic discrimination of beans, cross section morphology of seed coats was examined using the scanning electron microscope (SEM).
  In this examination, the morphology of seed coat textures of nine kinds of beans obtained in eastern Japan were observed. The cross sections of seed coats were prepared using a razor blade and coated with gold for the observation by SEM. Palisade parenchyma and cells of hypodermis were observed using XL30 scanning electron microscope (FEI, USA). Thicknesses of these cells were measured, and they were characteristic to each species. Inter-species discrimination among these samples was possible by comparing the ratio of thickness of palisade parenchyma and cell. Intra-species variation was recognized in four different kinds of soybean samples by the comparison of the ratio of cells and the shapes of cells.
  As a result, discrimination among the samples, except two soybeans, was possible by the morphological comparison of seed coat of beans. All samples discriminated each other by the combination with macrographical observation of their color.
  By these results, the morphological comparison of textures of seed coats by SEM was useful for forensic discrimination of beans.

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The high performance of the worm gearing, especially whose worm teeth are hardened and ground by conical grinder has become widely recognized. But this worm gearing has next outstanding problems. Namely, (1) The difficulty of the manufacturing of the hob cutter and maintenance of its accuracy. (2) The poor cutting ability of the worm teeth. Therefore we propose new methods to solve these problems. Namely, (1) Grinding method for worm wheel teeth by electro-deposited diamond wheels. (2) Generation for worm teeth by Mach type cutter. We actually manufactured new worm gear set by these new methods of manufacturing. And also we tested new worm gear reducer with these gear set and proved its high performance.

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In this study, extremely low cycle fatigue tests were performed on an aluminum alloy A6061-T6 subjected to thermal history ranging from 300℃ to 500℃, using U-notched and

cylindrical specimens respectively. The tests were undertaken under two-step strain control fatigue condition. The results are discussed in terms of effect of thermal history on the fatigue life and residual fracture ductility. The residual fracture ductility is influenced by thermal history, total strain range and cycle ratio. The fatigue life in two step fatigue is influenced by initiation of surface crack at the notch root and the thermal history.

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In order to improve the cutting performance of the

worm gear hob and improve the cutting conditions of the teeth on both sides, it is necessary to constrain the absolute value of the rake angle of each tooth to be small and control the balance of the rake angles on the left and right sides. Based on the principle of enveloping tooth surface formation (Dong, 1989; Wu, 2009), this paper proposes a method of forming a spiral groove rake face with a variable transmission ratio, so that the rake face of each tooth is formed in segments to achieve the design requirements of small absolute value and balance on both sides. Taking the basic worm speed ω of the hob, the moving speed v of the machine tool cutter, and the installation offset Δx of the cutter as experimental factors, taking the rake angle on both sides of five teeth of the hob as response values, a three-factor three-level response surface analysis method is used to establish mathematical models between each experimental factor and the rake angle on both sides, and analyze the interaction between each factor. The results show that: The order of influence of the three selected factors on the rake angle on both sides is: basic worm speed, machine tool cutter moving speed, cutter installation offset; optimize and obtain the optimal parameter combination for each of five teeth in a spiral groove, perform simulation processing and measure rake angle. The results show that the rake angles on both sides of five teeth are controlled within ±0.3°, which is 94% lower than that when five teeth are processed simultaneously with a fixed transmission ratio. This indicates that rake faces of small rake angle can be designed by optimizing processing parameters, which is conducive to improving and balancing the cutting performance of hobs.

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The crown worm drive is a new type of worm drive, it is consisting of an internal gear and a crown worm generating by the internal gear surface, and it is characterized with small size yet high-loading capacity. To satisfy the high precision requirement of crown worm tooth surface, a grinding method based on virtual center distance manufacturing principle is proposed and a grinding machine is reformed. A mathematical model was derived to calculate the theoretical probe center surface, and a measuring method is proposed to check the accuracy of crown worm tooth surface. A crown worm sample is manufactured and measured, the results show that the accuracy is 0.079mm on the upside tooth surface and 0.082mm on the underside tooth surface. The study is expected to provide the experimental foundation for the future application of the crown worm drive.

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The effects of Pb(II) on potassium dihydrogen phosphate (KDP) single crystal have been observed. It is found that the growth of the {100} face of KDP crystal is suppressed under traces of Pb(II), and that no tapering for KDP crystal by Pb(II) is observed. The pattern in KDP single crystal appears under traces of Pb(II). When measuring the distribution of Pb(II) between solution and prism-section crystal or pyramid-section crystals, the concentration of Pb(II) in both section crystals is higher than that in solution. Moreover, the concentration of Pb(II) in prism-section crystal is higher than that in pyramid-section crystal.

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Magnetite veins are commonly observed in serpentinized peridotite, but the mobility of iron during serpentinization is poorly understood. The completely serpentinized ultramafic rocks (originally dunite) in the Taishir Massif in the Khantaishir ophiolite, western Mongolia, contain abundant antigorite + magnetite (Atg + Mag) veins, which show an unusual distribution of Mag. The serpentinite records multi–stage serpentinization in the order: (1) Atg + lizardite (Lz) with a

texture (Atg–Lz); (2) thin vein networks and thick veins of Atg; (3) chrysotile (Ctl) that cuts all earlier textures. Mg# values of the Atg–Lz (0.94–0.96) are lower than those of the Atg (~ 0.99) and chrysotile (~ 0.98). In the Atg–Lz regions, magnetite occurs as arrays of fine grains (<50 µm) around the texture, and magnetite is absent in the thin Atg vein networks replacing Atg–Lz. Magnetite occurs as coarse grains (100–250 µm) in the center of some thick Atg veins. As the volume ratio of thin Atg veins to Atg–Lz increases, both the modal abundance of Mag and the bulk iron content decrease. These features indicate that hydrogen generation occurred mainly during Atg–Lz formation, and that the Mag distribution was largely modified by dissolution and precipitation in response to the infiltration of the higher temperature fluids associated with the Atg veins. The transport of iron during redistribution of Mag in the late–stage of serpentinization is potentially important for ore deposit formation and modifying the magnetic properties of ultramafic bodies.

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症例は60歳，男性．健康診断で胸部X線写真上右中肺野に辺縁が明瞭な円形陰影を指摘されたが，放置していた．その後咳嗽があり，当院を受診．胸部CTでは，右前胸壁の肋間筋を貫く脂肪濃度の腫瘤を認め，胸腔鏡補助下に手術を施行した．病理検査ではintramuscular lipomaであり，砂時計型の経胸壁型脂肪腫と診断された．胸壁の内側と外側に進展する経胸壁型の脂肪腫は極めてまれであり，胸腔内側の切除ラインを決定する上で，胸腔鏡は非常に有用であった．

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　二房性胆嚢は胆嚢の形態異常の一つとして臨床上比較的高頻度に経験され,先天性および後天性の種々の原因が考えられている.しかし,癌による deformityを強調する論文はわれわれの渉猟しえた範囲では見当らなかった.今回われわれは,ERCなどの胆嚢造影において胆嚢癌により二房性胆嚢の像を呈した2症例を経験し,臨床診断上示唆に富むものと考えここに報告した.2例の胆嚢造影所見から,1)ERCなどの直接胆道(嚢)造影により明瞭な胆嚢像を得ること,2)狭窄部分の多方向からの観察,撮影により同部の軸の偏位や拡がり,辺縁の性状をよく描出すること,3)圧迫法を併用していくこと,が鑑別診断のために重要と考えられた.

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