Base Circle Radius Research Articles

Axisymmetric Vibrations of Reinforced Orthotropic Shallow Spherical Caps

Axisymmetric vibrations of reinforced shallow. spherical caps manufactured from orthotropic materials are considered. The closed form solution is obtained for the natural frequency of the cap with a clamped and immovable circular edge by assuming that the motion component parallel to the cap boundary plane (in plane) is negligible. Parametric studies are performed to assess the effect of various geometric and structural parameters on the natural frequency of the cap and, most importantly, to identify the most influencing parameters of the problem. From the generated data, it is concluded that the national frequency increases with increasing extensional stiffness and eccentricity of reinforcements and to a lesser extent with increasing bending stiffness of reinforcements. Other important parameters include the base circle radius and the initial rise of the cap.

Mechanical efficiency of various large capacity scroll compressors.

This study presents the characteristics of the mechanical efficiency and the crankshaft speed fluctuation ratio of various large capacity scroll compressors. To introduce the different suction volumes of the scroll compresor, the scroll height and the involute base circle radius are individually increased proportionally based on a small capacity scroll compressor, and their effects on the mechanical efficiency and the speed fluctuation ratio are discussed. It was discovered that it is better to increase the involute base circle radius rather than the scroll height to obtain higher mechanical efficiency. Also it was discovered that the speed fluctuation ratio is nearly the same, independent of the scroll height and the involute base circle radius.

A computer-aided method for optimum design of plate cam-size avoiding undercutting and separation phenomena—II: Design nomograms

This study presents design nomograms which make it easy for the cam designer to estimate the limiting value of the investigated parameter which can be applied to a plate cam follower system, as long as the maximum contact stress between the cam and follower during both rise and return strokes of cam revolution can be determined. The undesirable phenomena of the undercutting of cam profile and the separation between the cam and the follower are taken into consideration. Moreover, these design nomograms give correlations between the investigated parameters and the optimum plate cam size and also are used to study the influence of an investigated parameter on this size. The optimum plate cam size is the combination of cam base circle radius and the amount of cam follower offset, and satisfies the suggested design procedure which is based on taking the contact stress as a design criterion. The investigated parameters are dynamic, kinematic, geometric and material. A brief discussion on using the suggested design procedure to design the size of plate cam is described. For a numerical example, the presented design nomograms are for reciprocating cam-roller-follower which operated by parabolic plate cam.

Geometry and Leakage Aspects of Involute Rotors for the Roots Blower

For maximum operating efficiency of Roots type blowers, the leakage of compressed air through clearance must be reduced to a minimum. At the same time it is desirable to keep the design as compact as possible. The following analysis endeavours to show, for involute rotors, the effect of the geometrical design variables, pressure angle, rotor tip radius, and base circle radius, on leakage and compactness. Firstly limits of permissible values of the geometrical design variables, to allow correct mating between rotors, are established. Within these limits, relative blower compactness and carry-over of compressed air back to the inlet tract is obtained for the ideal blower with no clearance between relative rotating parts. The analysis and results are expressed in dimensionless form independent of blower size, and results are compared with cycloid rotors. Leakage through blower clearances, in terms of the geometrical design variables, is then determined for a range of pressure ratios, and the dependence on blower size is examined. It is concluded that optimum design values cannot be obtained. A compromise solution between minimum total leakage and maximum compactness is necessary, depending on the operating requirements for a particular Roots blower.

Design Characteristics of Constant Diameter Cam : Contribution to Brunell's Paper

K. Brunell has disussed the basic properties and the design characteristics of the constant diameter cam, especially of the cam whose base curve is given as cycloidal displacement function. However it seems that his discussion is questionable in some points, so in this paper, correcting or supplementing his paper, the properties and the design characteristics of the constant diameter cam will be made clear. Let lift h, dwell angle β and cam base curve ν (θ) : 0gθgβ for follower's rise motion be given, then the cam base curve is given by [numerical formula] Let g be radius of the cam base circle, then the governing criterion is to be such a g that satisfies the following conditions for each θ such that 0gθgβ. g+v (θ)>0, g+h-v (θ)-v (θ)>0. If the condition v (θ)+v (β-θ)=h : 0gθgβ holds, the governing criterion becomes g+v (θ)>0 : 0gθgβ. Moreover we studied the constant diameter cam with cycloidal motion follower and we could express its governing criterion graphically.

A method of measuring transmission error in spur gears of 1:1 ratio

The transmission error of a pair of spur gears is detected by an optical method and recorded continuously as a function of time. Measurement of the alternating component of the error is repeatable within ?5 ? 10-5 in., and of the mean value within ?1 ? 10-4 in., at base circle radius, at any speed in the range 0-6000 rev min-1 and at any load within the capacity of the gears. Records are taken on photographic paper wrapped round a drum which rotates with one of the gears being tested. In this way the wavelength of record per cycle of tooth-engagement is made independent of speed and comparison of static and dynamic behaviour is facilitated. The method of measurement is applicable only to a pair of gears with the same number of teeth.