An experimental and theoretical investigation of noise and power reduction in high speed cable making machinery

Austin, Lisa (1998) An experimental and theoretical investigation of noise and power reduction in high speed cable making machinery. University of Southampton, Doctoral Thesis.

Abstract

This thesis describes research undertaken into Double Twist cable making Machines (DTMs). The project objective was to investigate the noise generated and power required by the DTM range, with an aim to reduce both.

This work identified that the bulk of the noise emitted by the machine was aerodynamic in nature, and its tonal characteristic indicated that the primary cause was the wake of a high-speed component (the "bow") striking fixed parts of the machine structure.

The experimental investigation indicated that the bows and wire-guidance dies were responsible for approximately 60% and 20% of the power requirements respectively. These power consumption results were used to create dimensionless coefficients, relating power consumption to machine speed, which established good correlation between machine sizes. General principles of aerodynamics were applied to develop a design methodology for the bow. The new bows demonstrated a 30% reduction in power consumption and a 50% reduction in acoustic power output.

The relationship between coefficient of drag and speed was obtained for DTMs; the results were comparable to published figures. A novel method of predicting the power that a bow shape would consume prior to manufacture was devised.

A detailed investigation into the acoustic pressure pulse characterized its nature and this, in conjunction with the power consumption investigation, led to a novel method of predicting acoustic output which can be used by manufacturers to reduce noise.

DTMs also suffer from wire breakage problems. Wire breakage occurs when the tension of cable entering the machine is insufficient to prevent the wire being pulled into the machine in an uncontrolled fashion. This results in a loop of cable escaping from the guidance dies, which is subsequently broken by win dage effects. A mathematical model of the dynamics of the wire-manufacturing process was created, which has led to an improved understanding of the mechanism of wire breakage and techniques by which it can be avoided.

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