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

这个小型企业创新研究（SBIR）二期项目将开发防止磨料水射流喷嘴磨损的技术，这限制了射流切割的使用寿命和精度，目前需要在更大的混合管中在喷嘴下游携带磨料。该方法包括一个多孔喷嘴，其周围是一个含有高粘度润滑剂的储层，该储层由驱动喷嘴中的浆液的同一泵加压。高速泥浆流动产生的压力差迫使润滑剂通过多孔壁面，形成一层薄膜，保护喷嘴内壁。试点试验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：一种是多孔润滑混合管（PLMT），可以改造到现有的商业系统中，另一种是多孔润滑磨料悬浮射流（plasjet），在注入之前预先混合颗粒。后者可以在较低的压力下操作，并使用较小的射流切割较硬的材料（微加工）。在第二阶段进行大量的切割和喷嘴磨损测试，以优化喷嘴材料、几何形状和制造工艺，并确定润滑油性能和注入速度。其他部件也将得到改进，包括颗粒和润滑剂给料系统。拟议技术的更广泛影响（商业潜力）将是磨料水射流，可用于从小型机械车间到汽车和飞机工业的各种用户切割和加工金属板，陶瓷和复合材料。在目前的系统中，混合管的磨损会限制喷嘴的使用寿命和切割精度，导致机器停机时间，并阻碍微射流的商业应用，从而对射流切割的所有应用产生不利影响。对市场上已有的数千个磨料射流系统进行最小投资的PLMT改造将大大减少这些不利影响。带有预混颗粒的plasjet还有几个额外的优点，可以降低成本并扩展射流切割技术的应用范围。实现相同切割效果所需的压力更低（例如10000 PSI与50000 PSI），更有效地使用磨料，并且更换喷嘴的频率更低，从而降低了成本。较低的压力也简化了紧凑型便携式系统的开发，用于在危险环境中远程应用，例如在核电厂退役期间，以及军事应用，例如清除地雷和其他障碍。此外，与混合管不同，等离子喷射直径可以减小到能够扩展喷射切割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.