Showing papers on "Pressure angle published in 1991"

A Procedure Using Manufacturing Variance to Design Gears With Minimum Transmission Error

Abstract: This paper deals with the design of spur gears that have minimum transmission error and are insensitive to manufacturing variance. We address two stages of design: (1) generation of candidate designs (selection of number of teeth, pressure angle, etc.), and (2) tooth profile modification. The first stage involves a search of discrete combinations of design variables, while the second stage utilizes numerical optimization techniques. The key research issue is finding a candidate design and its profile modification that not only has low transmission error, but is insensitive to variations in the design values caused by the manufacturing process. To achieve this goal, the procedure applies Taguchi’s concept of parameter design. In this paper, we consider a design problem with a set specification: fixed center distance, speed ratio, and transmission torque. We seek to find a limited number of candidate designs by applying conventional design generation techniques and some design heuristics. For each candidate design, the procedure determines the optimum profile modification (linear tip relief) by linking the Load Distribution Program (LDP) for gears with an optimization program package (OPTPAK). From the resulting peak optimum, we further seek the statistical optimum using an algorithm developed in this paper. The statistical optimum shows a nominal increase in the transmission error, but is quite insensitive to typical process error associated with gear manufacturing. The developed algorithm readily applies to other gear designs as well as other types of machine elements. In particular, we foresee our procedure to be particularly effective for helical gears. We hope to further our method by developing a means to add statistical heuristics to the discrete design generation stage.

Multistage sprocket assembly

Abstract: A multistage sprocket assembly having at least two sprockets having different diamters (13,14) and disposed adjacent to each other. The smaller sprocket (14) has a tooth (15) engageable with a portion of a drive chain to be displaced from the larger sprocket. The small sprocket tooth has a greater pressure angle (α) at a position thereof rearwardly relative to a sprocket assembly drive rotation direction than that of the other teeth of the smaller sprocket.

Speed reducer with displaced rollers

Abstract: The utility model relates to a speed reducer with displaced rollers, which is mainly composed of an inner gear ring, a rolling column tray and an input shaft with an eccentric bearing. The tooth profile of the inner gear ring is composed of circular arcs and tangent lines, and is basically fit with a theoretical curve. Dedendums and addendums are all in void contact with rolling columns, without the defect of an oversize pressure angle. The rolling column tray is provided with uniformly distributed radial slots; 1-3 rolling columns are arranged in each slot. The rolling columns are in rolling meshing engagement with an inner gear, under the push of the eccentric bearing; the speed is reduced by one tooth difference. The utility model has the advantages of small volume, easy fabrication, high efficiency, low noise and long service life. Single stage transmission ratio can reach about 90; supergiant type or supersmall type machines can all be manufactured.

Measuring apparatus of gear

Abstract: PURPOSE:To enable measurement of a tooth profile or a pitch of a large-side gear by a small-sized apparatus by rotating a displacement sensor under the control of a controller while moving it straight and by making it move to describe a basic involute tooth profile. CONSTITUTION:An X-axis moving mechanism 4 moves a displacement sensor 12 straight in the direction X intersecting perpendicularly a radial line prescribing a pressure angle with a straight line connecting a pitch point on the tooth surface of a gear 51 to be measured and the center of the gear, while the sensor is turned around the center of rotation of the gear by a turning table 3. Under the control of a controller, the sensor 12 is rotated by a minute angle theta by the table 3, while it is moved straight in the direction X intersecting the radial line perpendicularly by the moving mechanism by theta(Dp.cos alpha)1/2 (Dp is the diameter of a pitch circle of the gear and alpha the pressure angle). Thereby a probe 12a of the sensor 12 is so moved in linkage as to describe a basic involute tooth profile. Based on detection signals obtained from the sensor 12 by conducting a plurality of operations of movement in linkage, therefore, measurement is executed and the result thereof is recorded.

Finite-element analysis of ring gear/casing spline contact

Abstract: The speed reduction from turbine to propeller is achieved in the Pratt and Whitney PT6 turbo propeller engines through a two-stage epicyclic gear train. In this arrangement, the ring gear is locked to the casing through external splines. The orbitting of the planet gears generate cyclic stresses in the teeth fillets of the ring gear and the casing. The sliding contact between the steel ring gear and the casing splines generates wear. A two-dimensional finite-element computer program was extended to iteratively solve the problem of load-dependent contact between the splines. Using this program, the nonuniform distribution of the reactive load and the relative sliding on the loaded splines are calculated for any planet gear load position. The analysis predicts that the relative sliding reduces through a change in the spline pressure angle from 20-30 deg. Spline wear is practically eliminated in field engine gearboxes through this design change. The cyclic variation of the fillet stresses are also determined due to the orbitting planet load using a detailed network and by imposing boundary displacements. Qualitative comparison of the stress prediction is made using instrumented test results. The paper demonstrates the analysis procedure using a typical ring gear and casing combination.

歯車におけるポリアセタールの低摩擦化の効果 : 第1報, フッ素樹脂を充てんしたポリアセタールの場合

Abstract: It has already been reported that when nylon (MC nylon) was filled with synthetic wax, the coefficient of friction decreased, and in the case of using such wax-filled nylon for gears, the wear of teeth was reduced, and the amount of gouging of the teeth roots by the top corners of teeth on matching steel gears decreased: accordingly, the change of pressure angle became less. In order to confirm whether phenomena such as these may also occur in polyacetal or not, gears were made with material having a small coefficient of friction by filling polyacetal with fluorine-containing resin, and trial operation was carried out. The wear of teeth, change of teeth profile and other properties were examined, and by comparing them with those in the case of polyacetal gears without filling, the effect of reducing friction was investigated.

Synthesis of Contact Surfaces of Spherical Cam-Oscillating Roller-Follower Mechanisms: A General Approach

Abstract: A novel method of synthesis of the surface geometry of spherical cam-oscillating roll-follower mechanisms is introduced. The approach aims at zeroing the sliding velocity between the cam and the roller, their respective geometries being thus obtained as conical surfaces. The pressure angle is analyzed in detail. Specific results are presented for the application of this synthesis technique to indexing cam mechanisms.