Research on widening construction clearance on the transition curve of existing railway lines based on SIMPACK

This paper selects appropriate vehicle as the standard vehicle and designs its shape. Secondly, it chooses some control point on the vehicle according to the current standard. Thirdly, the essay sets four difficult operating conditions with different curve radius and superelevation, simulates on the SIMPACK software and compares the value of control points offset the centre of railway line to the current construction clearance. According to the result of comparison, this paper divides transition curve into three parts to widen construction clearance and proposes the definition of correction coefficient. At last, the paper compares construction clearance that has been corrected with existing construction clearance to check whether the new one is right or not. The study shows that if curve part is divided into three parts to widen construction clearance, it would be more reasonable and satisfactory.

Numerical Algorithm of Tooth Profile of Noncircular Gear Pair

According to the generating method theory, noncircular gear with all convex pitch curve can be processed by generating, author designed noncircular gear tooth profile, described a method of precisely calculating noncircular gear tooth profile. And proposed automatically optimizes the noncircular gear tooth profile meshing curve part separately by the identical rack cutting tool different side envelope. Through rack cutting tool along two gear center of rotation segment deviation pitch curve change modified quantity to avoid tooth undercut, realization nonzero modified. The driving gear and the driven gear tooth profile meshing curve part separately by the identical rack cutting tool different side envelope, guarantees when meshing zero clearance. The noncircular gear machined by this method has been used in real machine, which verifies the feasibility of the method.

On Programming for NC Grinding of Grooved Cam with Discretional Plane Curve Profile

In grinding of grooved cam, the programming for NC machining can’t directly be accomplished according to track curve of roller center in working drawing because the diameter of wheel becomes smaller than diameter of cam’s follower roller after wheel dressing. Track curves of wheel center are equidistant curves of the track curve of roller center and they can be gained by equidistant offset. But track curves of wheel center can’t be gained by equidistant offset for grooved cam with discretional plane curve profile, due to the profile including aspheric curves whose equations are usually unknown. To solve above problem, circular arc approximation for the aspheric curve part was realized by using Approximate Double Circular Arc Interpolated Method (ADCAIM), then equidistant offset of circular arcs was carried out by “offset” way, and consequently track curves designed for wheel center of any diameter can expediently be gained on AutoCAD platform. Validation experiment of simulation grinding was fulfilled on a NC milling machine. The experiment results indicate: it is feasible to NC grind grooved cam with discretional plane curve profile using the method introduced in this paper for the example.