The Powder Feeding System For Laser Powder Rapid Micao-Fabrication

In the 21th century, one of the trends of scientific and technological development is the microminiaturization, and the dimension is from millimeter to micron and nanometer. The technology of micron/nanometre enables mankind to enter a new phase of understanding and remaking nature and to realize another substantial improvement in terms of the volume of information processed in given cubic unit and the ability of motion control.The micromachines and the MEMS(micro electro mechanical systems is a marginal and crossed high technology research field that rised in 20th nineties. It refers to the machines that the dimension is in the size of millimeter or micron. The purpose of research on miniature is to develop components and systems with new theories or functions through microminiaturization and integration to form a new scientific discipline and industrial sector. The developed counties, such as American, Japan and German etc, all rank this research working as the key developing subject.Due to the successful development and the commercial production of the high power lasers, the laser rapid prototyping technology developing rapid in the 20th eighties. In the process of the laser rapid prototyping, there are two main developing direction: one is using this technology to produce the prototype of the parts, such as SLA－Stereo Lithography Apparatus,LOM－Laminated Object Manufacturing and SLS－Selective Laser Sintering etc；the other is to produce the solid parts , so that people could gain the tightness functional parts that have the using characteristics. This technology is also named as Directed Light Fabrication technology.In the process of micromachines, an important technological quota is the distinguishability. In the microscopic process of rapid fabrication, the distinguishability including the scanning distinguishability and the fabrication distinguishability. The fabrication distinguishability is the min-fabrication unit, is also named as the light solidification; the scanning distinguishability is the scanning shifting mechanism's min shifting distance.If thinking over the process of fabriction, the light solidification unit is the volume of the single laser pulse solids the metal powder, or the unit volume of the solidification trance that gained by the single track laser solidfying the mental powder. So, in the process of laser powder rapid micro-fabrication, to gain the fine light solidification unit, mainly should adopt two aspect measure:a),using the laser that have the mini-focus spot. Usually select the doubling frequency laser or fiber laser.b),using the micro-size particle diameter metal powder as the solidification material of the laser powder rapid micro-fabrication.Just taking these consideration, the NCLT of Beijing polytechnic university utilize the self technique superiority, combine the laser rapid manufacture technique and the micromachines research, put forward the innovation that using the nano/nano-phased powder as the solidification material of laser powder rapid micro-manufacture. Nano/nano-phased powder laser powder rapid mico-manufacture technique is the laser rapid formation technique's applyment and development in the micromachines fields.If we adopt synchronous feed powder mode in the process of laser powder rapid micro-manufacturing, then the technical precondition is to feed the Nano/nano-phased powder even, steady to the formation position. Due to the Nano/nano-phased powder's diameter is very small, it have the character that the normal micro metal powder that used in thelaser cladding don't have. The character includes the serious agglomerating and adsorbent and easy flowing power in the flowing gas phase. So Nano/nano-phased powder conn't be feeding with the powder feeding system used in the process of normal laser powder rapid fabrication. We must resign the powder feeding system that adapt to the laser powder rapid micao-fabrication. To resolve the Nano/nano-phased powder steady feeding project, this paper detail discuss the Nano/nan...