In high-speed carding machines, the breakage of tongue needles significantly affects the weaving quality of the fabric. ImageFigure 7-30 illustrates the frequent breakage points of the tongue needle. During the knitting process, the continuous impact between the tongue needle and the triangular valve, as well as between the needle tongue and the needle shank, is the primary cause of tongue needle breakage. The main sources of impact are: (1) Each time the tongue needle contacts the弯纱 triangle, it experiences an impact from the triangle; (2) Similarly, when the tongue needle touches the护针 triangle, it is also impacted by the triangle. The impact force from the 弯纱 triangle on the knitting needle lasts approximately 250 microseconds, making its impact pulse relatively flat.

Due to the high ratio of the impact duration of the bent needle triangle to the basic natural frequency of the tongue needle, there will be no longitudinal migration on the tongue needle. However, the impact shape of the guard needle triangle is steep, around...Within 5 to 10 microseconds, the impact force reaches its peak, causing the stress wave to rapidly propagate throughout the tongue needle upon impact with the needle guard triangle. Moreover, in that instant, the tongue needle's rapid deceleration will induce bending vibrations in the needle hook. Simultaneously, the impact force between the needle and tongue will exacerbate the bending deflection of the needle hook caused by the stress wave.

Petrov of the University of Rye in the UK tested the fracture characteristics of tongue needles. One of his significant conclusions is that the fracture of the needle hook should be due to wave formation, and the stress waves are formed by the impact of triangles and the needle's heel.