Automated Rotor Assembly CNC Machine

Abstract

The process of manually removing material to restore rotational balance to a rotor assembly can be time-consuming and labor-intensive. This results in the inability of tool shops and machinists to get through their queue during any current workday. In this paper, the design and creation of an automated system capable of removing material from rotor assemblies. The system will recognize inputs including part number, component dimensions, amount of material to be removed, and which surface the material will be removed from. The purpose of this system is to remove material from different planar surfaces with respect to inputs provided by the machinist. This will provide a more efficient and effective way to ensure the balance of a rotor assembly for use in the operation of an Auxiliary Power Unit (APU). Due to the complex architecture of the APU rotor assembly, a 3-axis milling technique was needed. A CNC machine was found to have the ability to move in the x, y, and z planes which would allow for the proper range of motion that is desired. In addition, the use of CNC technology was chosen due to the need for high accuracy and no conditions for complex angles. Due to the time constraints provided by the client for process completion, install, and removal a CNC design where speed can be controlled was chosen to meet these constraints. The design must be adaptable for use on varying sized rotor assemblies, it must have a removal limit of 0.001 milli ounces(moz), and run based on a code that incorporates a graphical user interface. This interface must be capable of accepting and using manual inputs along with being able to convert from one coding language to another. Initial prototyping was used to explore the accuracy and range of movement in both the x and y directions through the use of stepper motors controlled via g-code; an open-source code useful in controlling multiple stepper motors in 3 degrees of motion. Stepper motors were used due to their high torque and low speed as well as their reliability and accuracy. It was found that when given the same command repetitively the prototype was able to perform the action in the exact same manner as before making it have a high precision. The speed of the prototype was variable and cost was a little over $300 making it highly affordable. In order to interface with the CNC machine, custom software was designed and developed. After the initial testing, z-axis control was added into the design and is currently being tested. The outcome of the current prototyping phase is a system capable of moving in all three planes of motion.