Design and experiment of auto spreading and raking fascicles device for straw braiding machine

Abstract: Straw is a rich resource in quantity, but large amount of waste rice straw has been burned in the field, which causes waste of resource and environmental pollution at the same time. Straw is an important production resource, and the straw mats are widely used as a protective tool for bricks, buildings, agaric production and vegetable greenhouse, etc. According to literature and data reviewed, rice straw abroad is mainly used for field return and recycling, and straw mats braiding machine are rarely reported abroad. While in China, a type of mature flat straw braiding machine was widely used in the north. This kind of machine relies on human spreading and needs operators to stand on either side of the machine to continuously lay straws onto the conveyor surface regularly. It has many problems, such as high labor intensity, poor working conditions and so on. With the increase of labor cost, the demand for the automatic spreading conveyor of the machinery becomes more and more imperative. In order to realize mechanical feeding, improve working performance of the straw braiding machine and reduce the labor intensity, an automatic spreading and raking fascicles device for straw has been developed by simulating the actions of humans, which can be used as the matching equipment of the existing flat braiding machine. The device is composed of 2 parts: dip-angle bisecting spreading and multi-link raking fascicles. Straw can be proportionately fed into the braiding machine. Kinematic analysis of key components and parameter optimization are carried out by using ADAMS software. However, there are no available standards for the performance test of the weaving machines. In addition, the weaving quality of the straw mats are related to weaving speed, straw quality, evenness of laying and many other factors, and there are also many uncontrollable factors. While considering these, experimental tests have been firstly performed to find out the relationship between weaving speed and needle frequency (fz) of the flat straw braiding machine, and taking laying thickness as the index, to test the working performance of the auto spreading and raking fascicles device. Prototype testing were carried out at different weaving speeds, and the operating frequency range of 3 components, which are the dip-angle bisecting spreading, multi-link raking fascicles and knitting lock device, were obtained. In order to test the working condition of the automatic device and the weaving quality of the straw mats, fascicles rate (Fs) and leak rate (Lb) are used as the evaluation indexes which have been contrastively analyzed at 3 different weaving speeds and corresponding operating frequencies during the complete machine performance test. The results indicated that mean thickness of the spreading straws is less than 40 mm from auto spreading and raking fascicles device, which can accord with the design requirements for the following weaving process. And used with the flat straw braiding machine, the fascicles rate (Fs) of the straw is 92.12% and the leak rate (Lb) is 5.44%, when the needle frequency (fz) is 0.8 Hz, weaving speed (vb) is 90 m/h, and setting the frequencies of the dip-angle bisecting spreading (ft) and multi-link raking fascicles (fp) as 0.8 Hz and 1.13 Hz respectively, which can meet the use requirements. Compared with traditional manual feeding method, the use of the device reduces labor cost and improves production efficiency. It can reduce 2 workforces at the constant weaving speed, increase the annual income by nearly 8 640 yuan for each machine. In addition, the device is driven by link motion, shock and vibration will occur during the weaving process. In this experiment, the influences of velocity and acceleration changes of each component on straw spreading efficiency and whole machine properties need to be further analyzed and verified.