Influences of Bobbin-Counter Weight Mass Balance on the Appearance and Mechanical Properties of Braids

Abstract

The purpose of this study is to examine the effects of balance between bobbin weight and counter weight on the appearance and mechanical characteristics of the braid. The thickness of the braid showed thinnest when the counter weight mass was 40% of the total masses of bobbins and became thicker as the balance was lost, and the braiding angle of the braid became sharper when the counter weight mass became larger than 40%.
Regarding the bending characteristics, the amount of deflection of the braid increased as the weight balance increased, and the braid became softer. Regarding the tensile properties, the elongation under a 100 N tensile load tended to decrease and the elongation elastic modulus increased as the weight balance increased. It became clear that these mechanical properties had close relationships with the axial crimp as well as the thickness and the braiding angle of the braid.
During the production of the braid, a horizontal force due to the weight bobbins and a vertical downward force due to the counter weight that forms the length are applied and tightened. Since the thickness of the sample formed with a weight balance of 40% showed thinnest and was an intermediate value for the other measurement values, a horizontal force by the weight bobbins and a vertical force by the counter weight affects the structure of the braid, and when this balance of forces was optimal, compaction of the braid and length formation became efficient and a thin and uniform braid was formed. The empirical knowledge of the conventional skilled craftsmen that the weight balance at the time of braiding should be approx. 40% was confirmed.