Design And Key Technologies Research Of Smart Cutting Tool Based On Cutting Force Sensing

To meet the requirements of high-efficiency, high-accuracy and high-reliability machining processes, especially for cutting difficult-to-machining materials, the cutting tools play a crucial role to obtain components with stable high-quality and high accuracy integrity surface. Tool wear and breakage directly affect the quality of the surface on processed components, it is necessary to monitor and control the condition for cutting tools during processing. It is needed to provide the cutting tools system more functions in order to breakthrough the materials and size limits in processing difficult-to-process materials and the large dimension surface, as well as to reduce the tools wear, extend tools working life. This project proposed a smart cutting tool system, aiming at the demands of real-time condition monitoring and multi-function for cutting tools. The basic idea is the ability of real-time cutting force monitoring the cutting tools has during processing, and the system also has the ability with vibration assisted processing according to the demands for the processing. The processing quality could be increased, the working life could be extended and the processing ability of the diamond cutting tool could be improved through ulrasonic vibration machining.This dissertation first established the equivalent physical model-piezoelectric beam for the cutting tool system based on the basic thought and design principles of smart cutting tool systems, and analyzed the stress distribution rules under the applied three directions of force. It analyzed the combined vibration path of end face mass points of the beam according to the exciting type of bending vibration of the piezoelectric beam, thus established the vibration path function of the end face mass points of the beam, and provided basis theoretical instruction for the design of the sensing principles of the smart cutting tool and the design of the vibration system.To achieve measurment and decoupling three components cutting force, it proposed a model of cutting force sensing smart cutting tool, through the tool-bar integrated micro three directional forces measuring system, merged the micro three directional forces measuring system with the cutting tool into one component, achieved the autonomously real-time monitoring of the micro three direction forces. Through building the equivalent piezoelectric cantilever beam of the smart cutting tool, established the coupling relations between output charge of the sensing elements and the three components cutting forces, and achieved decoupling through the combination of sensing elements. Deducted the charge distribution of each sensing element in detail under applied cutting forces in each direction, and established the mapping relation between three cutting force components with the output charge of the four piezoelectric sensing elements, and thus established the decoupled sensing equation of the three components cutting forces and sensing elements output charge. Corrected the decoupled sensing equation of the sensing type smart cutting tool through calibration test, thus obtained the corrected decoupled equation.In order to test and evaluate the designed cutting force sensing smart cutting tool, first the LabVIEW program is used to establish test platform of the three direction cutting force decoupling algorithm, to realize the real-time measuring if cutting force. Through cutting experiment to statically calibrate the sensitivity, realized the accurately decoupling of the three direction cutting force, and then comprehensively evaluate the performance of the smart cutting tool, analyzed the affecting rules of the structural parameters. And finally the feasibility of the decoupling method the design of the smart cutting tool is validated through comparative experiments.In order to further enhance the stiffness, sensitivity and practicability of the cutting force sensing smart cutting tool, an improved cutting force sensing smart cutting tool was proposed, by changing the type of cross surface in sensing section, the assembly type of sensing elements, and the design of the index-able carbide insert cutting tool, improve the practicability of the smart cutting tool. Established the stiffness and charge sensitivity analyzing model of the sensing system, optimize design the type of cross surface in sensing section and the assembly type of sensing elements, analyzed the dimension parameters of the cross surface in the sensing section and the relation between stiffness and sensitivity, realized sensing ability of minimal0.1N for the main cutting force.To improve the processing ability of the diamond ultra-precision machining, decrease cutting tool wear, extend the cutting tool working life, proposed and investigated an ultrasonic vibration type sensing smart cutting tool, which characterizes two aspects: elliptical ultrasonic vibration processing, and real-time monitoring of vibration machining process. According to excitation method of bending vibration of the piezoelectric beam, adopted the bi-directional bending vibration mode to realize the elliptical path forming, and based on vibration principles of the end surface mass points and the vibration sensing principles, designed the structure of the ultrasonic vibration sensing smart cutting tool. And on the basis on the analyze of the vibration performance of equal cross surface, analyze the vibration performance of the smart cutting tool system, and determined the structural parameters of the cutting tool, then deduced the output force coefficients.In order to improve the vibration output performance, the size of the piezoelectric elements should locate in the field between the vibration nodes of cutting tool side surface. Through the vibration and sensitivity test, evaluated the vibration frequency, amplitude and temperature characteristics, and determined the proper excitation parameter and sensing ability. Calibrated the vibration sensing cutting tool, and obtain the relation between the output voltage and the cutting force, realized the monitoring of vibration processing. Finally, it analyzed the machining process of the cross surface, and the influence of process parameters to the machining. The ultrasonic processing ability and real-time sensing capability of the ultrasonic vibration sensing smart cutting tool are validated through comparison experiments.