Computer control of powder flow for solid freeforming by acoustic modulation 教程.pdf

Powder Technology 133 (2003) 251– 254 /locate/powtec Short communication Computer control of powder flow for solid freeforming by acoustic modulation Shoufeng Yang, Julian R.G. Evans * Department of Materials, Queen Mary, University of London, Mile End Road, London E1 4NS, UK Received 9 October 2002; received in revised form 4 April 2003; accepted 15 April 2003 Abstract This communication describes a method for both on/off and flow rate control of dry powders in open capillaries using acoustic vibration. In a glass capillary attached to an electromagnetic transducer, the wave characteristics of the forced vibration control both flow rate and switching of powder flow. The valve is free from relative movement of parts that may wear or seize in the presence of fine powders. The versatility of the flow controller has been demonstrated by playing popular music to a sample of H13 tool steel powder. The on/off switching and the flow rate of the powder correspond to the waveform of the music. D 2003 Elsevier B.V. All rights reserved. Keywords: Powder metering; Powder dispensing; Rapid prototyping 1. Introduction thermal conductivity zones or corrosion-resistant coatings could be built into the computer design at source and In solid freeforming of materials, a three-dimensional assembled as an integral operation, subject to their metal- shape is create