| In the process of disaster rescue,such as building collapse and debris flow,the accident of reinforcing bar penetrating into human body often occurs.In this kind of accident,due to the complex working conditions,the space is generally relatively narrow.The existing steel bar cutting equipment is generally heavy,large volume and other problems,restrict the narrow space for steel bar cutting rescue.In this paper,the third generation of grinding and cutting rescue device of the research group is optimized to further miniaturize and lightweight and improve the mobility,so that the device can achieve the completion of steel bar cutting in a narrow space.At the same time,the vibration part of the grinding cutting rescue device is optimized to improve the cutting efficiency of the grinding cutting rescue device.Specific results are as follows:1.According to the cutting and rescue needs of the steel bar penetrating into the human body in a narrow space,the shell of the third generation device is designed to be lightweight and small,and the manual two-degree-of-freedom movement is introduced to improve the mobility.Compared with the third generation device,the new device has a weight reduction of 23% from 11.6 kg to 8.9 kg,and a size reduction of 19% from557×185×142 mm to 500×180×132 mm.The movement Angle of the front end of the device is increased to 110°,which improves the degree of freedom of the device and enables the device to achieve the cutting of steel bars in a narrow space.2.The vibration grinding of the third generation device is realized by the built-in eccentric motor instead of the abrasive wheel shaft with additional eccentric mass excitation.At the same time,in order to reduce the weight and volume of the cutting part,the Angle mill is replaced by a high-power DC motor,and the shell of the cutting part is optimized.The finite element simulation of the key parts of the new vibration structure is carried out,and the effectiveness of using eccentric motor to provide vibration is verified by calculation.3.A dynamic model is established for the vibration optimization part of the new device,and important parameters such as damping stiffness in the model are calculated and identified.The amplitude response curves of the vibration part under different excitation frequencies were measured.The amplitude-frequency-characteristic curve and timeresponse curve of the device were obtained by two-degree-of-freedom dynamics analysis and Runge-Kutta solution.The curves were compared with the measured curves to verify the correctness of the calculation.Then,the theoretical cutting track of a single abrasive particle is calculated.On this basis,the mechanism of improving grinding efficiency by introducing vibration is analyzed,and the cutting ability and grinding efficiency of the device can be improved by introducing vibration is verified theoretically.4.Through orthogonal test of feed speed and excitation force,the specific grinding energy in cutting process is compared,and the introduction of vibration can reduce the specific grinding energy,improve the grinding efficiency,and get the appropriate working parameters.Through the cutting ability comparison test,it is verified that the improved device has further improved the cutting ability of steel bar compared with the previous. |
