Oil delivery balancing and priming for multi-diameter minimum quantity lubrication tooling assemblies

摘要

Multidiameter tooling assemblies are widely used in high volume machining to reduce tool changes and maintain concentricity between features. In minimum quantity lubrication (MQL) applications, the internal coolant passage geometry in the assembly must be carefully designed to ensure oil delivery to all edges and adequate time response during tool changes. Such assemblies also lose oil over time in the tool changer, and require periodic priming or “baptism,” which results in lost production time and wasted oil.In this paper, the oil balancing problem is analyzed by treating individual coolant passage using a resistance analogy. This novel method results in better balance compared to standard production tools as documented through oil collection measurements. Extending the electrical analogy, the priming time and response time for the assembly are analyzed by comparison to an RC circuit. In this approach, both priming and response time depend on the resistance of the assembly to oil flow and the capacitance of the assembly to store oil. Based on this approach, it is shown that priming time can be greatly reduced by priming at a maximum oil level dependent on the assembly’s resistance, and that in typical operations most tools can be primed as part of the tool change cycles without an additional priming cycle. The implications for MQL tooling design and the estimation of tooling assembly oil capacitance are also discussed.