Lumped Parameter Modeling and Parameter Investigation of An Electrohydraulic Crimping Hand Tool
Date of Award
Master of Science (MS)
A lumped parameter model of a hand-held electrohydraulic tool was developed. The tool modeled was a Milwaukee Tool M18 12 Ton Crimper. First principle approaches were used to develop state-space models for each of the subsystems in the tool. The included subsystems were the tool motor and gear train, pump, return valve, and cylinder. The subsystem models were combined into a comprehensive eleventh-order nonlinear dynamic tool model. The tool model has two inputs and three outputs. The model inputs were the motor voltage and opening the return valve. The outputs were the motor current, application time, and retraction time. Each subsystem and the comprehensive tool model were simulated and experimentally validated.Tool model simulations were able to predict the position of the tool ram with an average maximum error of 4.4% with respect to the maximum position when crimping a 750 MCM copper splice and Burndy YGHC29C29 grounding connector. Model simulations were able to able to predict the power consumption of the tool with an average maximum error of 6.9% with respect to the maximum power.A parameter investigation was performed to suggest possible design changes to decrease tool power consumption. One independent parameter, the pump piston diameter, was varied. The pump piston diameter was linked to the gear train ratio through the maximum torque at the motor. Increasing the gear train ratio and the pump piston diameter reduced the energy consumption by reducing the average load torque and current draw of the motor. The negative effect of these changes is the gear train and piston will have to increase in size and weight. The energy consumption could be reduced by as much as 30% while maintaining a gear train that would meet the size and weight requirements to be used in a hand tool. The decrease in energy use would increase the number of crimps from 49 to 70 with the tool using a Milwaukee Tool M18 CP2.0 battery.