天然橡胶机械化采收锯切功耗影响因素试验

锯切式割胶是天然橡胶机械化采收的重点研究方向之一,该文以锯切式割胶装置为研究对象,开展锯切功耗影响因素研究。该文设计了天然橡胶锯切功耗测量试验台,研究了锯片直径、锯片齿数、切割电机转速、进给速度对锯切式割胶装置切割功耗的影响。构建了以切割电机转速、进给速度及锯片齿数为因素,以切割功耗为指标的割胶刀具切割功耗影响因素模型,并进行了三因素三水平的正交试验。试验结果表明,各因素对切割功耗影响的主次顺序为锯片齿数、进给速度、电机转速、锯片直径;同时得到在给定因素水平下,切割参数最佳组合为进给速度为30 mm/s、电机转速为500 r/min、锯片齿数为10齿,此时电机切割功耗最小,功耗值为2.597 J。该研究可为天然橡胶机械化采收装置的设计提供参考。

Experiment of influence factors on sawing power consumption for natural rubber mechanical tapping

Natural rubber (NR) is an important economic crop in tropical regions of China and is also an indispensable strategic resource which has excellent capability. With the growing shortage of tappers, mechanization of NR tapping becomes an inevitable trend. There are many studies on cutting characteristics of agricultural and forestry crops both at home and abroad. However, the study on the cutting power consumption of rubber mechanical harvesting is still blank, so it is necessary to carry out independent experiments on NR bark. The selection of cutting parameters is very important in mechanized harvesting. Cutting parameters will affect the cutting ability of the cutter. In order to reduce the power consumption of the NR mechanized harvesting sawing cutter and prolong the working time of the mechanical tapping equipment in the forest, the influence factors on sawing power consumption were studied. At first an experiment bench for NR tapping was developed based on the actual working conditions. The bench was mainly composed of a sawing cutter, a data acquisition module, a feeding motion module and a microcontroller. Sawing cutter was fixed on the ground, while cutting samples were mounted on feeding motion module which was able to supply cutting force. Saw blade could be replaced to change the diameter and the teeth number, and both the motor speed of the cutter and the speed of the feeding module could be adjusted through programming. The DC (direct current) stabilized voltage power supply was connected in series with the isolating transmitter and sawing cutter. The output of the isolation transmitter was connected with the microcontroller. And the microcontroller was used to collect the instantaneous current of sawing motor. Then the data were transmitted to the computer through the RS232 serial port and the computer could calculate cutter power of motor as an experiment evaluation index. All samples were taken from Xiqing Farm in Danzhou City, Hainan Province. The truncated tree was untapped and the tree bark was original. Meanwhile, all cutting samples with size of 50 mm × 30 mm × 5.5 mm (length × breadth × height) were cut from a same truncated tree and in order to simulate the actual cutting condition, the sample was pruned into trapezium. The cutting samples were tested within 2 h to prevent the biological characteristics of samples from changing. Then single factor experiments were conducted, and the effect of the diameter and the teeth number of saw blade on power consumption was tested by using different saw blades with different teeth numbers and diameters, while that of the motor speed of cutter and the feeding speed of samples was tested through changing programs. And the results showed that the diameter of saw blade had no significant influence on power consumption, and the teeth number, feeding speed and motor speed had significant influence on power consumption. Power consumption decreased with the decrease of teeth number and motor speed, while it increased with the decrease of feeding speed. Finally an orthogonal experiment with 3 factors (teeth number, feeding speed and motor speed) and 3 levels was carried out based on the single factor experiments. And the results indicated that the significant level order of the effect of different factors on power consumption from high to low was teeth number, feeding speed and motor speed. Moreover, the optimal sawing parameters for NR mechanical tapping were obtained as follows: Teeth number was 10 teeth, feeding speed was 30 mm/s, and motor speed was 500 r/min, and under the optimal condition the cutter power of motor was 2.597 J. As the selection of cutting parameters is essential for NR mechanical tapping devices, which significantly affects the working ability of the tapping devices, this study can provide a reference for the device design of NR mechanized tapping.