Influence of geometric parameters of the rotary hook on interaction of its elements in high-speed modes sewing machine

The purpose of this paper is to develop the analytical model of the rotary hook geometric parameters’ interconnections, which allows determining the characteristic modes of interaction of its elements. In this study, the interaction mechanism of the bobbin case, the rotary hook and the support finger was defined, which allows to reduce the unit vibro-impact activity.

As practice shows, the bobbin case sometimes turns against the rotary hook movement. This phenomenon can be used for the free passage of the needle thread. The change in the geometric parameters of the rotary assemble will allow to decrease its vibro-impact activity.

The interrelations of rotary assemble geometric parameters are established, and it is possible to determine the characteristic modes of its elements interaction and to establish a mechanism for controlling them. This allows reducing the vibro-impact activity of joint, improving friction modes and sewing technology. Criteria and values of a gap formation between the right contacting face of bobbin case and support finger protuberance are found.

In the future, it is necessary to conduct research on the behavior of the rotary assemble elements in the frequency operating modes of the sewing machine. It is necessary to show the influence of the resonance modes of operation of the rotary hook drive on the interaction of elements.

The practical use of the results of the work makes it possible to reduce the vibratory impact of the shuttle, and also to create conditions for the smooth operation of the rotary hook and the bobbin case, and ensure the formation of a gap between the contacting face of bobbin case and support finger protuberance for the free passage of the needle thread. The results of the work can be used in the design of a rotary assemble with specified characteristic parameters and modes of elements interaction.

An analytical model of interrelations of geometric parameters of a rotating hook is developed. The characteristic modes of interaction of the rotary assemble elements were studied. The reasons for the vibro-impact activity of the rotary hook are studied. Also, the conditions under which the bobbin case will move against the direction of rotary hook rotation are determined.