Structure Imorovement And Performance Test Of Knotter Driven By Two Toothed Discs With Same Tooth Direction

This article focuses on the problems of low worm transmission strength,tripping failure,and high bracket processing cost discovered during the production process of the knotter driven by two toothed discs with same tooth direction.Proposed the improvement plan for the structure of the rope clamping transmission mechanism and knotting nozzle,as well as a CNC processing plan for the knotter bracket.Bench tests and field experiments on rice and wheat harvesting and bundling of the improved knotter have been conducted.The main research content of this article is as follows:(1)In response to the problems of low worm transmission strength and tripping failure during the production process of knotters,a structural improvement method for the rope clamping transmission mechanism and the tripping surface of the knotting nozzle is proposed.By using Gear Trax,KISSsoft,and Solidworks software,the parameters of the small tooth disc bevel gear and worm drive were adjusted and optimized according to the transmission requirements,increasing the gear strength and improving the reliability of the rope clamp transmission mechanism.Remodel the release surface of the knotting nozzle,increase the contact area between the release surface of the knotting nozzle and the corresponding release position of the knife arm,thereby improved the tripping failure caused by the knotting nozzle.(2)The knotter bracket is an important component of the knotter.In response to the difficulty in machining its shaft hole and surface,as well as the high cost of the original five axis machining method,a machining method for the spatial shaft hole of the knotter bracket and the design of a special fixture for CNC machine tools are proposed based on the positional relationship between each shaft hole of the knotter bracket and the coordinate transformation of machine tool machining.Finally,use a handheld 3D laser scanner to perform high-precision scanning of the processed bracket.The point cloud was processed using Geomagic Wrap software,and the bracket processing error was analyzed to determine that the component processing accuracy met the design requirements.In subsequent research,the improved knotter will be subjected to bench and field tests to verify its performance and reliability.(3)In order to conduct performance tests on domestic improved knotters,a test bench for continuous knotting of multiple sets of knotters has been developed.This test bench can accurately simulate the operation of the knotter under the condition of grass bale rebound.The knotter’s knotting speed,number of knots per unit time,rope loop size,and rope tension can be adjusted,and three knotters from different manufacturers can be tested simultaneously.The real-time rotation speed,angle,and rope tension of the spindle are automatically measured,recorded,and saved.The tying process is accurately and automatically counted,and the data can be displayed in real-time on the industrial touch screen.The improved knotter was tested on a test bench and tied about 9000 times.The results showed that the improved knotter could work reliably under the conditions of rope tension of 100-160 N and spindle speed of 70-90 r/min,and the knot formation rate fully met the inspection requirements of the current JB/T 11200-2011 "Square Bale Baler Knotters".(4)To verify the field performance of the knotter driven by two toothed discs with same tooth direction designed in this article,50 acres of wheat and 50 acres of rice were harvested and bundled using a World Group’s harvesting and bundling integrated machine.During the experiment,three levels of grass bales with lengths of 400,500,and 600 mm were selected for testing,maintaining a feed rate of 3 kg/s for the harvester,resulting in a total of approximately 3900 bales.The experimental results show that the improved knotter has achieved the design requirements for bundling rate and good overall coordination.