RESUMO
The vibration of the micro-milling tool presents a significant chaotic vibration phenomenon, which has a great influence on the tool life and part machining precision, and is one of the basic problems restricting the improvement of machining efficiency and machining accuracy in micro-milling. To overcome the difficulty of the traditional vibration measurement method with the online measurement of micro-milling tool multi-dimensional vibration, a three-dimensional (3D) measurement method of the micro-milling tool is proposed based on multi-fiber array coding, which converts the tool space motion into a decoding process of the optical coding array employing the tool modulating the multi-fiber array encoding. A 6 × 6 optical fiber array was designed, and a 3D motion platform for micro-milling tools was built to verify the characteristics of the optical fiber measurement system. The measurement results show that the measuring accuracy of the system reached 1 µm, and the maximum linear error in x-, y-, and z-direction are 1.5%, 2.58%, and 2.43%, respectively; the tool space motion position measurement results show that the maximum measurement error of the measuring system was 3.4%. The designed system has unique coding characteristics for the tool position in the space of 100 µm3. It provides a new idea and realization means for the online vibration measurement of micro-milling tools.
RESUMO
TiB-whisker-reinforced TiBw/TC4 composites are widely used in aviation, aerospace, automotive, and various other industries. However, the drilling force and temperature have a large effect on the drilling micromechanical properties of TiBw/TC4 composites. In order to explore the micro-mechanical properties and promote the optimization of drilling process, the representative volume elements of TiBW/TC4 composites were established in the Digimat-FE software tool to determine the micromechanical properties and failure mechanism of TiBW/TC4 composites. The results show: (1) maximum stress occurs at the whiskers, whereas the minimum stress appears within the basket matrix region of the reinforced phase. (2) When the force reached 300 N and the temperature reached 75 °C, the junction between the whiskers and the matrix firstly failed; when the force reached 525 N and the temperature reached 112 °C, the matrix began to fail; when the force reached 675 N and the temperature reached 138 °C, the whiskers failed. (3) The main reason for the failure of the junction between the matrix and the whiskers was that the shear stress exceeded the connection strength and the axial stress accelerated the failure process. Displacement and rotation of the whiskers were shown to occur at the moment of junction failure, owing to differences in the stress experienced on different sides of the material.
RESUMO
In this paper, a novel differential reflective intensity optical fiber angular displacement sensor was proposed. This sensor can directly measure the angular and axial linear displacement of a flat surface. The structure of the sensor probe is simple and its basic principle was first analyzed according to the intensity modulation mechanisms. Secondly, in order to trim the dark output voltage to zero, the photoelectric conversion circuit was developed to adjust the signals. Then, the sensor model including the photoelectric conversion circuit has been established, and the influence of design parameters on the sensor output characteristic has been simulated. Finally, the design parameters of the sensor structure were obtained based on the simulation results; and an experimental test system was built for the sensor calibration. Experimental results show that the linear angular range and the sensitivity of the sensor were 74.4 and 0.051 V/°, respectively. Its change rules confirm the operating principle of the sensor well.