SBIR Phase II: Development of Porous Lubricated Nozzles for Suppression of Nozzle Wear in Abrasive Water Jet Systems

该小型企业创新研究（SBIR）第二阶段项目将开发用于防止磨料水射流中喷嘴磨损的技术，该技术限制了射流切割的寿命和精度，目前需要在较大的混合管中夹带喷嘴下游的磨料。 该方法包括一个多孔喷嘴，喷嘴周围有一个储液器，储液器中装有高粘度润滑剂，润滑剂由驱动喷嘴中浆料的同一泵加压。由于高速浆料流产生的压力差迫使润滑剂通过多孔壁，并形成保护喷嘴内壁的薄膜。中试已成功地将喷嘴磨损降低了一个数量级以上。目前正在开发两种系统：一种多孔润滑混合管（PLMT），可以改装到现有的商业系统中，以及一种多孔润滑磨料悬浮射流（PLAS-Jet），在注入之前预先混合颗粒。后者可以在较低的压力下操作，并以较小的射流切割较硬的材料（微加工）。在第二阶段进行的广泛的切割和喷嘴磨损测试将优化喷嘴材料、几何形状和制造程序，并将确定润滑剂特性和注射速率。其他组件也将得到改进，包括颗粒和润滑剂进料系统。 拟议技术的更广泛影响（商业潜力）将是磨料水射流，可用于切割和加工金属板，陶瓷和复合材料的不同用户，从小型机械车间到汽车和飞机行业。现有系统中混合管的磨损通过限制喷嘴的寿命和切割的精度、通过引起机器停机时间以及通过阻止微射流的商业应用而不利地影响射流切割的所有应用。以最小的投资对市场上已有的数千种磨料喷射系统进行改造的PLMT将大大减少这些不利影响。带有预混颗粒的PLAS-Jet具有几个额外的优点，可以降低成本并扩展射流切割技术的应用。实现相同切割效果所需的压力更低（例如10000对50000 PSI），磨料的使用效率更高，喷嘴更换频率更低，从而降低了成本。较低的压力还简化了用于危险环境中的远程应用的紧凑便携式系统的开发，例如在核电厂退役期间，以及用于军事应用，例如清除地雷和其他障碍物。 此外，与混合管不同，PLAS-Jet直径可以减小到使射流切割扩展到精密微加工的水平。

This Small Business Innovation Research (SBIR) Phase II project will develop technology for prevention of nozzle wear in abrasive water jets, which limits the lifetime and accuracy of jet cutting, and currently requires entrainment of abrasives downstream of the nozzle in a larger mixing tube. The method consists of a porous nozzle surrounded by a reservoir containing high viscosity lubricant pressurized by the same pump that drives the slurry in the nozzle. The lubricant is forced through the porous walls by the pressure difference generated due to the high-speed slurry flow, and creates a thin film, which protects the nozzles' interior walls. Pilot tests have successfully reduced the nozzle wear by more than an order of magnitude. Two systems are being developed: A Porous Lubricated Mixing Tube (PLMT) that can be retrofitted into existing commercial systems, and a Porous Lubricated Abrasive Suspension Jet (PLAS-Jet) with premixed particles prior to injection. The latter enables operation at lower pressures, and cutting of harder materials with smaller jets (micro-machining). Extensive cutting and nozzle wear tests during Phase II will optimize the nozzle material, geometry and manufacturing procedures, and will determine the lubricant properties and injection rate. Other components will also be improved including the particle and lubricant feed systems. The broader impact (commercial potential) of the proposed technology will be abrasive water jets that can be utilized for cutting and machining of sheet metal, ceramics and composites by diverse users, ranging from small machine shops to the automotive and aircraft industries. Wear of the mixing tube in present systems adversely affects all the applications of jet cutting by limiting the lifetime of the nozzle and accuracy of the cut, by causing machine-down time, and by preventing commercial applications of micro-jets. A PLMT retrofitted with minimal investment into the thousands of abrasive jet systems already in the market will greatly reduce these adverse effects. The PLAS-Jet with premixed particles has several additional advantages that reduce the cost and extend the applications of jet cutting technology. Cost reduction results from the lower pressure required for achieving the same cutting effect (e.g. 10000 vs. 50000 PSI), the more efficient use of the abrasives, and the less frequent replacement of nozzles. The lower pressures also simplify the development of compact portable systems for remote applications in hazardous environments, such as during decommissioning of nuclear plants, and for military applications, e.g. removal of mines and other obstacles. Furthermore, unlike mixing tubes, the PLAS-Jet diameter can be reduced to levels enabling expansion of jet cutting to precision micromachining.