To Calculate the Loading of Knitting Needles of Automatic Half-Hose Machines

Abstract

An important link in the analysis of the longevity of details by the criterion of fatigue strength is the calculation of parameters that take into account the peculiarities of the technological regime in terms of load and the corresponding number of cycles that affect the accumulation of fatigue failure. The final range of loads of knitting needles of automatic half-hose machine was based on the systematization of amplitudes of forces depending on the frequency of their implementation. Previous works has assumed the assumption of a one interaction of the needle heel with the cams, which is experimentally refuted by the example of modern high-speed automatic half-hose machine. The aim of the work is to adjust the provisions of calculating the load of knitting needles of half-hose machines for design estimate of longevity, taking into account the specific features of the impacts of needles with the cams of the knitting system, which affect the total number of load cycles. The condition of rupture of the contact in the pair of the needle heel and the inclined cam after their impact is considered, taking into account the inertial and rigid parameters of the system, including the resisting force of the needle in the groove of the cylinder. According to the results of the dynamic analysis, the expressions of the minimum speed at which the needle can rebound from the cam and the vertical component of the needle rebound speed at the moment of its separation from the cam are obtained. The analysis of the influence of the force of resistance of the needle movement in the race on the vertical speed of the needle is performed. The issue of the bounce of the heels of unselected needles from the lower edge of the inclined cam due to their inertial run-out was studied separately. It is established that at certain circular speeds of the needle cylinder leads to additional impacts of the needles with the horizontal limiting cams and increases their destruction. The results of studies of the possible rebound of the needle heel from the inclined cam and the interaction of the needle with the limiting horizontal cams are a supplement to the method of calculating the loading of needles and are aimed at improving the accuracy of design longevity of needles.