Development And Experimental Of A Spindle Mounted Mechanical Self-Decoupled Force/Torque Sensor

Intelligent manufacturing is the main direction of China’s construction of a manufacturing power,and its development level is related to the global status of China’s future manufacturing industry.For the manufacturing industry,real-time monitoring technology of the cutting process,as an important condition for its realisation of intelligent manufacturing,can improve the production efficiency,product quality and core competitiveness of enterprises.As one of the most important monitoring variables in the cutting process,the measurement of cutting force is of great significance for product quality,cutting parameter optimisation,tool condition monitoring and tool vibration measurement.Currently,sensors are usually mounted on the machine table,under the tool insert and on the spindle in three positions for cutting force monitoring.The first two methods can have certain restrictions on the size and shape of the workpiece or are not versatile for the tool.In addition,the sensors used are basically optimised in their structure or the data is processed by certain algorithms in order to obtain the magnitude of the individual components of the cutting force.Therefore,this paper proposes a spindle-type mechanical self-decoupling force/torque sensor based on the magnetostrictive inverse effect,which can be applied to the machine tool spindle,using a mechanical structure self-decoupling decoupling method and a wireless passive detection method to measure the cutting force information of the machine tool,providing a new decoupling path for cutting force sensors.Firstly,the force-magnetism transformation process of magnetostrictive materials when magnetostrictive inverse effect occurs is analysed.A model of the wireless passive detection system of the sensor in this paper is established according to its effect,and the mathematical transformation relationship between force-magnetism-electricity when the sensor detects the load is obtained through theoretical analysis.The specific development process of the sensor is then unfolded according to the sensor decoupling path.The design requirements of the sensor and the design ideas of the key core components are described,as well as the mechanical self-coupling process of the sensor for the coupling forces consisting of axial force and torque.By means of ANSYS finite element simulation and modal analysis software,the simulation verifies the designed sensor mechanical self-coupling principle and the design requirement of uniform force in the sensitive area,and the inherent frequency of the sensor model is obtained.Finally,after machining,assembly and commissioning,a prototype of the sensor meeting the technical requirements was obtained.Secondly,based on the results of the force simulation analysis,the mathematical relationship between strain and load in the sensitive area of the sensor is derived using mechanics-related knowledge.In order to verify the principle of self decoupling of the sensor in this paper at the theoretical level,the matrix relationship between strain and load in the sensitive area of the sensor is established to verify the principle of mechanical self decoupling of the sensor at the theoretical level.The relationship between the load and the frictional force/frictional torque generated by the relative motion of the decoupled structure when the two decoupled nodes of the sensor are working decoupled is also analysed.The influence of the friction of the two decoupling nodes on the decoupling performance of the sensor is also discussed in the light of existing research results.Finally,the basic performance experiments including calibration,dynamic stability and hysteresis characteristics of the sensor were carried out using the existing sensor performance test platform in the laboratory.The results show that the sensor has good basic performance parameters and its cross-talk is low,which verifies the mechanical self-coupling capability of the sensor developed in this paper at the practical experimental level.In addition,a sensor cutting test platform was designed and built to carry out actual cutting experiments under different working conditions and different materials.The experimental results show that the cutting forces collected by the sensor and the standard sensor in the measurement area have good consistency and accuracy.