The Research And Design For Structure And Hydraulic Control System Of Log Grapples

At present, with the increasing demand of timber harvesting and tending, especially for artificial forest, the development of forest machinery and equipment is also raised. However, the development of forestry machinery in China is slow, the equipment function is relatively simple, the comprehensive operation efficiency is low, and the research of harvesting equipment mainly depends on skidding and handling, and does not have sawing operation and other more function of harvesting and tending. In this paper, according to multi-function operation demand for forest cutting and tending, the design of the forest logging grapples can be integrated to complete the logging, centralized bunching bucking operations, greatly improve the efficiency of the work and reduce the labor intensity.Firstly this paper does mechanism analysis according to the requirements of operation device, in view of the clamping mechanism and sawing mechanism characteristics, puts forward appropriate organization scheme, and optimizes the mechanism scheme and size. Using Pro/E to establish the CAD model of the log grapple, and optimize the assembly.According to the clamping operation state and performance of log grapples, the method combines software simulation and theoretical analysis is adopted in this paper. Kinematic and dynamic simulation analysis are carried out for log grapple in the Pro/E software. Using MATLAB software to solve the symmetry analysis model of two grippers and dynamic numerical model established for clamping process, getting the time domain curve of the force of two sides of the hinge joints and two-force bar in clamping process. Comprehensive check and evaluation can be done by combining two kinds of analysis results, and optimization criterion of parameters can be obtained by using numerical model solution.Using ANSYS Workbench 14.5 to carry out the static analysis of the overall structure in clamping and sawing operation condition respectively and analyze the strength and stiffness of larger-bearing critical hinge pin shaft, thus further verify the reliability of the design.According to the operational requirements, carrying out the numerical analysis and calculation of the parameters of each actuator, determining the operating parameters of the hydraulic system, and accomplishing the device selection. Adding the load-sensing and pressure-compensated control into the hydraulic system, for the specific requirements of different actuators, and designing their hydraulic circuit. Using AMESim software to simulate and analyze the hydraulic system, evaluating the working performance of the hydraulic system in driving the actuators of the log grapples.