Determination of dynamic component reactions in support bearings of rotor saws for cutting hot rolled (message 1)

Abstract

A distinctive feature of rotary saws is the process of cutting the workpiece, which takes a very short time. For example, a workpiece with a diameter of 200 mm is cut in 0.2 seconds, while traditional designs of sliding and pendulum saws perform this operation in 10-20 seconds or more. This effect is achieved due to the high speeds of feeding the disc to the cut, exceeding traditional modes by 20 or more times. However, due to the specific cutting conditions, weak links were identified in these designs that require further improvement. One of the factors that reduces the reliability of the saw is the insufficient durability of the bearings of the high-speed disk shaft, which perceives the cutting force. Until now, the reliability issues of rotary saw structures remained unresolved. One of the factors that reduces the reliability of the saw is the insufficient durability of the bearings of the high-speed disk shaft, which perceives the cutting forces. Practice shows that the applied methods of calculating the strength of support bearings do not allow taking into account all possible factors that affect the reliability of bearings in the cutting process. First of all, as it turned out, during operation, the saw blade has radial runout, possibly due to an error when cutting the teeth of the blade and the eccentric landing of the blade on the seat when replacing it. For modern rolling mill production, the issue of strength and reliability of rotary saw designs, which are intended for cutting rolled metal, is relevant. The purpose of this work is to determine the precise values of the reaction forces of the support bearings of the disc shaft. As you know, during long-term operation of the object, the place for landing the cutting disc on the faceplate wears out, sometimes there is an error in the hole when making a new disc. Therefore, there is an eccentricity of the center of gravity of the disk. The presence of this eccentricity is taken into account in the work when determining the required forces using D'Alembert's principle of conditional balancing of forces. Due to the fact that the process of cutting with a circular saw is very short-term, the cutting force is considered the impact force. The magnitudes of the reaction forces in the bearings are determined during cutting using the impact dynamics theorems: the momentum theorem and the kinetic momentum change theorem. By projecting the vector formulas of the principle and theorems on the coordinate axis, the systems of algebraic equations are obtained, from which the horizontal and vertical components of the reaction forces in the bearings are determined both in idle mode and during cutting. Due to the fact that the vector of the centrifugal Dalembert force of inertia of the disk changes its direction, the formulas of the reaction forces at different positions of the center of gravity of the disk were obtained. According to the results of the planned numerical analysis of the problem, graphs of the dependences of the horizontal and vertical components of the pressure forces on the bearings can be drawn from: the eccentricity value, the vertical and horizontal components of the cutting forces, the angular velocity and the position of the disk