Cutting brittle rods using elastic wave propagation

Pavel Šidlof,Martin Pustka,Zdeněk Braier

doi:10.24132/acm.2021.624

Abstract

For the sake of intended industrial applications, the stress wave propagation in thin rods of brittle material is measured and explored. Based on the known theory of a non-dispersive wave propagation in rods, a numerically efficient method for the calculation of wave propagation and reflection is presented. The effects of an impact applied to a thin rod are tested and measured on a test bench. The results of these measurements carried out on glass capillary tubes are successfully compared with theoretical results and they confirm the possibility of brittle rod cutting by means of elastic waves with the required fracture surface quality.

Highlights

The glass blanks for the quality seed bead and chaton production are manufactured by separating small-diameter tubes or rods into short pieces
For a rod of brittle material having much higher compressive than tensile strength, the separation of the end section may occur by virtue of induced tensile stress
If the rod end section to be separated is weakened by a circumferential notch, the fracture occurs at the notch position and the fracture surface is of a high flatness, perpendicular to rod axis and without chips

Summary

Introduction

The glass blanks for the quality seed bead and chaton production are manufactured by separating small-diameter tubes or rods into short pieces (so-called preforms). The pursuit of a quality surface achievement commonly increases production efforts and reduces their efficiency For these reasons a new cutting technology based on an elastic wave propagation in a thin rod [12] was developed and experimentally verified. If the rod end section to be separated is weakened by a circumferential notch, the fracture occurs at the notch position and the fracture surface is of a high flatness, perpendicular to rod axis and without chips This method allows the making of quality preforms with high production rate and reproducibility. The strain histories are compared with the theoretical non-dispersive wave propagation

Theoretical model

Wave packet reflection at a rod free end

Wave resulting from the impact of two rods

Measurement of waves in a glass rod

Conclusion