Kind Of Gear Research Articles

浸炭歯車の歯面の改善と面圧強度に関する研究 ３ 油膜形成に及ぼす歯面仕上げの影響

It is very difficult to finish precisely the surface roughness of gear tooth to the extent of a few sub-micron meters by a grinding machine. Even if it is possible, a time for grinding tooth will be very long and a grinding bum may often occur. The authors have adopted a barreling process as a last finish process for improvement of the surface roughness of the ground or the shot peened gears. And they found that this process is very effective for improving only the surface roughness of gear tooth which may have a slightly tooth tip relief and/or crowning. In the present research, four kinds of gears which are the ground gear, the ground and shot peened one, the ground, shot peened and barreled one, and the shot peened and barreled one without grinding were prepared. Their surface durabilities were investigated using a gear testing machine which can measure the condition of oil film formation between a pair of gears during running. Though the tooth profile of the ground, shot peened and barreled gear did scarcely change after running, that of the ground and shot peened one changed remarkably. The duration of the oil film formation in a running test conducted using barreled gears was very good, but that of the ground and shot peened gears was very bad.

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.

The Ultimate Motion Graph

The innovation was to develop a gear geometry that reduces or eliminates gear noise and increases the strength of gears. Gear noise is a common problem in all bevel and hypoid gear drives. A variety of expensive gear geometry optimizations are applied daily in all hypoid gear manufacturing plants, to reduce gear noise. In many cases those efforts have little success. Additional expensive finishing operations (lapping after the grinding) are applied to achieve the goal of quiet and stong gear sets. The ultimate motion graph is a concept for modulating the tooth surfaces that uses a physical effect to cancel out the dynamic disturbances that are naturally generated by all up-to-date known kind of gears. The ultimate motion graph also eliminates the sensitivity of gears against deflection under load or displacements because of manufacturing tolerances. Lower dynamic disturbances will also increase the dynamic strength. [S1050-0472(00)00203-8]

Basic Theory on Tooth Contact and Dynamic Loads of Gears. 3rd Report. A Pair of Tooth Profiles without Variation of Bearing Loads under Given Ratio of Angular Velocities.

When the location of gear axes and the constant ratio of angular velocities are given, a pair of tooth profiles having a straight path of contact that coincides with the common contact normal at each point of contact is expressed by algebraic equations. The common perpendicular to the gear axes and the axis of relative rotation which is defined in the static space by the given ratio of angular velocities determine the static coordinate system, in which the design point P0 and the path of contact are determined as follows. In the case of cylindrical or bevel gears, P0 is chosen arbitrarily on the axis of relative rotation and the path of contact is chosen as a straight line through P0. In the case of other kinds of gears, P0 is chosen arbitrarily on the horizontal plane which includes the axis of relative rotation and is perpendicular to the common perpendicular, and the path of contact is chosen as a straight line through P0 which lies on the normal plane that is perpendicular to the relative velocity at P0. When the path of contact and its common contact normals are transformed to the coordinate systems rotating with each gear, a pair of tooth profiles without variation of bearing loads is obtained.

Flexible three dimensional gear modelling

ABSTRACT We present a formulation for describing flexible gear pairs in the three dimensional analysis of flexible mechanisms. The set of holonomic and no-holonomic constraint equations that defines the behavior of gears is developed. The formulation is capable of representing almost any kind of gears used in industry: spur gears, bevel gears, hypoid gears, racks, etc. All reaction forces due to gear engagement are accounted for. Teeth flexibility, clearance and mesh stiffness fluctuation are introduced in the model by relating deformation along the normal pressure line to the normal forces acting on teeth.

Calculation Method of Cutting-Edge Profile of Globoidal Worm-Shaped Tool for Finishing Helical Gear.

In this paper, exact calculation methods for cutting-edge profiles of two kinds of globoidal worm-shaped tools for finishing a helical gear with an arbitrary tooth profile are proposed. One is a globoidal worm-shaped tool which is in line contact simultaneously with many teeth of a helical gear finished by it. The other whose cutting-edge profile is the same in all sections including the tool axis, is in point contact with the helical gear to be generated. The latter can finish many kinds of gears with different numbers of teeth or helix angles. By substituting zero for the number of threads, these methods are applicable to a form-grinding wheel.

Dynamical aspects in flexible rotating machinery

Flexible multi-rotor systems are defined as rotor assemblies consisting of flexible shafts and rigid bodies which perform small motions with respect to arbitrary nominal rotations, each rotation being different for different rotor in general. The application field of such mechanical systems is quite broad: e.g., turbine modelling as well as in any kind of gears. To solve the governing equations, a procedure is proposed which makes use of minimal velocities along with a Ritz series expansion. In the first step, a single flexible rotor is considered which is then used as a subsystem for the second step. The theory is illustrated by an application to a two-stage planetary gear. In order to substantiate this procedure, a short review of methods applied to a flexible rotor is presented, starting with the most popular in the field of flexible systems, i.e., Hamilton's Principle. It is one aim of the paper to elaborate the relation between different procedures in a way as to enable a convenient choice to be made. To this end, a Central Equation will be derived which contains many known procedures as special cases. The theoretical analysis then links theory and practice and provides theoretical results amenable to practical calculations. The resulting equations require minimum effort and are applicable to any multi-flexible axisymmetric rotor system having parallel axes of prescribed rotation.

A study on fatigue and dynamic performance of induction-hardened sintered powder metal gears. (Case of module 2, standard pressure angle 14.5.DEG. and contact ratio 2.172).

A conventional skew gear pair does not change its relative position of gear axes. On the contrary, one of the axes of the gear pair offered in this paper is able to be displaced one-parametrically on the space fixed to the other gear axis. At any relative position of the gear axes, the gears rotate at a constant speed ratio. The displaceable axis gear pair has three backgrounds as follows. (i) The gear pair is potentially a power transmission element. (ii) The motion of these gears can be applied to the generating motion of gear manufacturing. (iii) The gear tooth bearing problem is based on a deflection or displacement of the gear axis in loading. This paper discusses the relative curvature of gear tooth surfaces and the motion of the tooth bearing pattern.2145Three kinds of induction-hardened sintered powder metal gears were fatigue-tested using a power circulating gear testing machine in order to elucidate the fatigue strength and failure mode. The relation between the tooth profile change and the dynamic performance in the fatigue tests of the gears were also investigated. The fatigue strengths of three kinds of gears were almost the same. The failure modes in these gears were tooth breakage at the tooth fillet, tooth breakage due to pitting near the pitch point, and destructive tooth surface failure. Except for one case of the destructive tooth surface failure, the dynamic performace changed slightly during the fatigue test since the tooth profile deterioration was small. The occurrence of the destructive tooth surface failure influenced the dynamic performance of the gear.

The natural history of the Hardangerfjord

Abstract As part of a joint survey of ‘The natural history of the Hardangerfjord’ a study was made of its fish fauna. The investigated area comprises Hardangerfjorden and the system of fjords and sounds between the islands west of it, to the coast. The main field work was carried out during 1956 to 1958 by various kinds of gear, with supplementary investigations in 1959, 1960, and 1963. A total of 186 stations was investigated. The material was supplemented with occasional catches of fishes during other investigations, information from the litterature and local informants, and specimens available in museum collections. The aim of the survey was faunistic. No attempt was made to study the population dynamics or the detailed ecology of the species. The distribution of each species in the area is described, together with such biological and other information as the material allows. In all, 126 marine species have been recorded from the area. An anadromous form of Salvelinus alpinus has also been observed, and there are 9 further species, for which there is not specific enough information to include them at present in the fauna of the investigated area. Of the 126 species, 26 are considered more or less occasional visitors, 11 others are stationary only in the outer part, outside the fjord itself. The deep waters of the investigated area, that is, below about 100 m, are very uniform as to temperature and salinity throughout the year, and the corresponding fish fauna is also very uniform. The shallow-water fish fauna, down to about 10 m, at 13 serial stations from the outer coast to the inner fjord branches was investigated five times. The fauna, grouped into four subareas, is described, and the number of species in each is compared with earlier findings for the hard-bottom littoral fauna and for the benthic algae. While there was a clear reduction in the number of species in the two last groups from the coast to the inner fjord branches, no such reduction was found in the number of fish species. For many species there was, however, a clear reduction in the number of specimens from the coast inwards. The shallow-water fauna showed a marked difference between February, when it was fairly poor, both as to species and specimens, and the period June to October/early November.

Limiting Load for Scoring and Frictional Loss of Hypoid Gear : In Comparison with Spur Gear and Crossed Helical Gear, Using Mineral Oil and Synthetic Oil

The limiting load for scoring and frictional loss of the hypoid gears were compared with those of the spur gears and the crossed helical gears. As lubricants were chosen not only the mineral oils but also synthetic oils and a new relationship between limiting load for scoring among these three kinds of gears and the frictional loss of these gears was also investigated. The limiting load for scoring differs depending on whether it is the lubricating oil with Zn-P additive or the mineral oil with EP additive, or synthetic oil. Further the relative defference between the velocities (V1 and V2) of tooth surfaces, which engage each other, is found one of the most important factors for determining the load carrying characteristics.

Power Transmission Efficiencies and Friction Coefficients at Teeth of Novikov-Wildhaber and Involute Gears

New equations have been derived to calculate the power transmission efficiencies, at the meshing teeth, of two kinds of representative cylindrical gears, Novikov-Wildhaber and involute gears. The efficiencies could be calculated from the equations and the friction coefficients obtained by simple experiments with test rollers. In order to show clearly the difference in the power transmission efficiencies of the two kinds of gears, the authors designed and made two interesting gear pairs with a small number of pinion teeth (Z1 = 3) and with a high gear ratio (Z2/Z1 = 9) by applying new techniques developed by them. The effects of gear speed, tooth load, type of lubricant, etc. upon the power transmission efficiencies were clarified using two interesting techniques to measure the efficiency. The experimental results indicated that the efficiency of the Novikov-Wildhaber gears was appreciably higher at high speeds, while it was lower than the involute gears at the start of rotation and also at low speeds.

トルク比一定の歯車に関する研究 (第4報)

It is well known that gears used in watches are designed considering the influence of center distance variation.The purpose of this paper is to compare the characteristics of IF gears with those of several other kinds of gears under the influence of center distance variation.The results are summarized as follows.1) The variations in torque ratio and velocity ratio of IF gears are smaller than those of conventional watch gears.2) Usually, IF gears have smooth transition of contact from one pair of teeth to the next in spite of center distance variation.3) IF gears show the maximum efficiency levels, even when the center distance is decreased.

An Annotated List of the Fishes of Lake Texoma, Oklahoma and Texas

During 10 years of collecting with several kinds of gear, 71 species have been collected from the main body, headwaters, tailwaters and inundated tributaries of Lake Texoma. Annotations on ecology, reproduction and abundance are included.

Selectivity and Effectiveness of Certain Types of Commercial Nets in the T.V.A. Lakes of Alabama

Abstract Trammel, riprap and gill nets with nylon webbing of 3-, 3.5- and 4-inch bar measure were fished under supervision by commercial fishermen in the T. V. A. lakes of Alabama to determine effectiveness of such nets for taking rough fish. Several types of sets were used of which the whip-set trammel was most effective followed by the fixed trammel, riprap and gill net. Mesh of 3-inch bar measure was generally most efficient for taking rough fish. During the period November, 1955, through May, 1956, 10,425 fish weighing 42,689 pounds were taken in the several kinds of gear and of these 95.4 percent were rough fish.

釣掛式電動機装荷方式における電車用片当り防止歯車

The gears, which are used in the nose-suspended motor of a motor car, necessarily come to mesh at the end of face width on account of the mechanism of motor suspension. This mechanism is usually the cause of gear tooth failures. In order to prevent the gear tooth failures, the traction gears of motor cars of the Japanese National Railway are crowned. From the results of investigations to introduce the method of deciding the form of crowning of gear, the author found that the total length of the face width of the nose suspension type traction gears used at present does not share the load effectively. Thereupon, the author tentatively designed the gear, which has the face width reduced to 2/3 and is crowned.Further, the author designed the tentative gear which is divided into two pieces, gear rim and gear boss, which are connected by the compression type rubber unit buffer. In this gear the gear rim can displace itself in relation to gear boss and the uniform tooth bearing all over the face width can be expected.These two kinds of gears which were manufactured to prevent the gear tooth failures were set on the axles of motor car, and the running experiment to test the functions of the gears were carried out. By measuring the fillet stresses with the wire resistance strain guages, the author confirmed that the trial gears had the expected functions. The results are as follows:1. In the crowned gear with reduced face width, the load is shared over all the length of the face width effectively, and the maximum fillet stress of the gear tooth appeared at the middle of the face width and was of sufficiently safe magnitude.2. The gear having the compression type rubber unit buffer has the uniform tooth bearing all over the face width, and the function to prevent the uneven contact was confirmed.These gears fabricated for trial are being tested for practical use at present.