In the sawing process, vibration and noise from the blade are significant issues. One effective method to control these is by introducing appropriate slots on the blade. This paper aims to provide a mathematical basis for designing slotted blades and reusing blades with radial root cracks. To achieve this, we treat radial slots and cracks as equivalent and analyze their impact on blade vibration using finite element analysis.
To begin, we examine the vibration characteristics of a standard circular saw blade. The blade has an outer diameter of 2a = 1.0 m, thickness h = 0.006 m, clamping diameter ratio f = 0.5, Young’s modulus E = 2.058 × 10¹¹ N/m², Poisson’s ratio v = 0.3, and density r = 7.8 × 10³ kg/m³. Due to axial symmetry, only half of the blade was modeled, divided into 90 quadrilateral plate elements with 114 nodes (5 radial divisions, 18 circumferential divisions). Using SAP6, we calculated natural frequencies and post-processed the results with a custom program to identify vibration modes (m = number of nodal circles, n = number of nodal diameters).
To test the effect of mesh density, we increased the number of elements to 180 (222 nodes) and 360 (407 nodes), dividing the blade into 10 and 36 equal parts respectively. Results showed that lower-order natural frequencies were consistent across different mesh densities, confirming that 90 elements are sufficient for practical applications.
Next, we analyzed blades with radial grooves, which can also represent radial root cracks. Grooves of width less than 1 mm were evenly distributed. The model was divided into 180 units with 216 nodes. Slots were replaced with blank elements, and various slot lengths and numbers were tested. The frequency changes were recorded, showing that slotting causes some modal frequencies to split, dispersing energy more effectively during excitation.
The results indicated that as slot length increases, natural frequencies decrease gradually, but when the slot-to-radius ratio is below 0.2, the frequency drop is minimal, so bending stiffness remains unaffected. Increasing the number of slots also slightly reduces frequencies, but the effect is small. When crack length is less than 20% of the blade radius, dynamic performance remains stable, allowing continued use after stress relief and balancing.
This study provides insights into how slotting affects blade dynamics, offering guidance for blade design and repair.
Timing Belt Replacement,Serpentine Timing Belt Replacement,Fan Belt,Fan Belt Replacement
Zhoushan Aosheng Auto Transmission Belt Manufacturing Co., Ltd. , https://www.aoshengbelt.com