A New Design of the Tooth Profile for Single Screw Compressors
The wear of star wheel teeth is an importance issue in the single screw compressor. In order to enhance the wearresistance of star wheel teeth, some new profiles of the meshing pair were proposed to replace the currently used straight line envelope profile, such as single column envelope, multi-straight line (or multi-column) envelope. In this paper, a curved surface of the tooth flank is suggested. The groove flank is the envelope surface corresponding to the curved surface of the tooth flank. Section profile of the new tooth flank is a curved line, which could be elliptical, hyperbolic or involute. During the tooth meshing with the groove, the contact line between the tooth flank and the groove flank could move back and forth in the whole area of the tooth flank. This design is expected to improve the lubricating between the tooth flank and the groove flank, and to prolong the service life of the single screw compressor. Geometric and kinematic investigation of the star wheel and the screw rotor is established. And a new designed tooth flank of the meshing pair is introduced in this paper. Numerical control high-velocity cutting technology is suggested to fabricate the new star-wheel and the screw rotor.
A Design Method of Engaging Couple Profile of Single Screw Compressors Enveloped by Multi Straight Lines
AbstrcatThis paper introduced a new design method of rotor teeth profile and star-wheel teeth profile enveloped with multi straight lines in a single screw compressor.A teeth grove surface of a single-screw is repeatedly machined by a specially designed lathe with straight-lined cut feeding in different directions and positions,and these directions and positions of cut feeding are reasonably determined,so that,different regions of a generator on a teeth surface can be machined by different cut feedings.Recording to all those straight lines in different directions and positions,we can construct an ideal star-wheel teeth profile with these lines.The screw rotors and star wheel teeth profile machined in this way will provide excellent engagement in the compressor operation.It is predicted that this engaged couple will have less wear,better sealing in operation and have more easily manufacturing property and lower cost.
The Undercutting of Circular-Cut Spiral Bevel Gears
Undercutting is a serious problem in designing spiral bevel gears with small numbers of teeth. Conditions of undercutting for spiral bevel gears vary with the manufacturing methods. Based on the theory of gearing [1], the tooth geometry of the Gleason type circular-cut spiral bevel gear is mathematically modeled. The sufficient and necessary conditions for the existence and regularity of the generated gear tooth surfaces are investigated. The conditions of undercutting for a circular-cut spiral bevel gear are defined by the sufficient conditions of the regular gear tooth surface. The derived undercutting equations can be applicable for checking the undercutting conditions of spiral bevel gears manufactured by the Gleason Duplex Method, Helical Duplex Method, Fixed Setting Method, and Modified Roll Method. An example is included to illustrate the application of the proposed undercut checking equations.