Study On Measuring Tension Of Belt Drive By Vibration Frequency

Belt drive is an important form of mechanical transmission,commonly friction belt uses friction between the tensioned belt and the pulley to transfer movement and power.Because of these advantages: no need lubrication,low maintenance costs,with buffer vibration and overload protection,belt drive is widely used.The tension force is an important parameter to ensure that if belt drive can operate normally.If the tension is too small,the friction is small,belt drive will prone to slip and its efficiency will be reduced,but also the belt will be overheating and burning;If the tension is too large,the belt will be easily fatigue,and its life will be reduced,shaft and bearing force will increase.In order to ensure the required tension,there are basically two ways to measure the tension: First,based on the deflection,apply a load on the middle of the belt and the cut point of the pulley,by measuring the midpoint of the deflection to get tension force;Second,based on the natural frequency method,by measuring the free vibration frequency of the tensioned belt,that is,the natural frequency to determine belt tension.In terms of tension measurement based on frequency,there are so many foreign patents and products,but no related basic theoretical research.Therefore,this paper studies the theoretical and experimental on measuring the belt tension force by the vibration frequency method,and provides theoretical basis for the design of the tension measuring device.The main research contents are as follows:(1)A free vibration model of the belt tensioned on the pulley and in a stationary state was established,and the belt was simplified as a cable.In the case of considering only the geometrical stiffness caused by the tensioning force,a general formula formeasuring the tension of the belt is obtained.Under the condition of considering the geometric stiffness and physical stiffness(flexural rigidity)of the belt,theoretically,the tension-natural frequency calculation formula greatly improved its accuracy.(2)Elastic modulus is an important physical parameter of the material,and the main material of the belt is rubber,considering the aging of rubber and viscoelastic materials with creep and stress relaxation phenomenon,the actual elastic modulus of the belt is quite different from the value in the manual or the standards.Methods of measuring the elastic modulus of different materials are introduced,and tests of elastic modulus and tension of the belt are prepared.(3)The existing experimental system of belt drive is reconstructed,and an experimental test system is built to test the tension and elasticity model of the belt.(4)For the two types of V-belt,the elastic modulus and the natural frequency of free vibration of the belt are measured experimentally.Then,according to the tension force-natural frequency calculation formula,theoretical value of the tension force is obtained from the natural frequency measured by the experiment.(5)The experimental results show that there is a certain error between the theoretical value and the actual value of the tension force,but with the natural frequency changes,qualitative relationship is consistent,indicating that the theoretical analysis of the tension-natural frequency calculation formula has a certain degree of reliability.The concept of tension correction coefficient is introduced,and the formula of the correction coefficient is obtained by using the least squares method.After the introduction of the correction factor,accuracy of the measurement of tension by vibration frequency method improved.