1. 3 current status of research on fine potato excavators at home and abroad
At present, the potato precision dispensers can be divided into mechanical precision dispensers and gas exact chargers, depending on the method of work. Air-powered precision dispensers have many advantages, such as high seed quality, high operational speed, low injury rate and good generality, but their structure is complex and expensive. Mechanical precision dispensers are widely used in seeding devices, mainly because of their simple structure, low cost and ease of repair。
Mechanical precision dispensers consist mainly of spoon bands, spoon chains, spoon discs, needles, etc. Spoon-chained precision cutters can be replaced to meet the requirements of different sizes of seed seeding, have the advantage of being replacement-friendly, generic and more widely applied. However, there are also a number of disadvantages in this type of seeding, such as a spoon chain structure that can cause damage to the seeding of potatoes and affect the production of late potatoes. In relative terms, since it has the advantages of reliable work, good generality and higher precision of planting, spoon chain precision is gradually being replaced as the type of dispenser currently used by most of the world's potato precision seeding machines. Spoon-based precision dispensers are structured in a simple and general manner, but they are uneven and less reliable. Although the size and shape of a needle-strangler is not high, it has a more serious injury, and the study of this type has been discontinued by national and international scholars。
Aerodynamic precision dispensers may be divided by their method of work into aerobic precision dispenser, aerobic precision dispenser and aerobic precision dispenser. The geometric dimension of seeds is not high, is universal and does not harm the seeds, thus greatly increasing the precision of seeding, but is structurally complex and costly to manufacture。
1. 3. 1 status of research on fine potato excavators abroad
The study of precision seeding machines for potatoes from abroad began earlier in the late nineteenth century. In order to reduce the labour intensity of workers, some developed countries in europe and the united states developed simple machines, mainly for artificial cultivation, to sow potatoes. In 1880, ransomes and sims in the united kingdom, among others, developed animal power-driven two rows of potato seeding devices using artificial semi-automatic seeding, the world's early potato seeding machines. By the late 1930s, the potato plant had emerged, with initial semi-mechanization. Starting in the middle of the 20th century, the precision seeding of potatoes was rapidly developing and gradually automated. As a result of continuous improvement, the precision seeding machinery of potatoes abroad is superior to that of the state, both in terms of productivity and performance. The precision seeding machines of foreign potatoes have gone from semi-mechanization to automation, and have achieved fruitful results in basic theoretical research and technical levels. Currently, there is a wide variety of mechanized equipment for potato cultivation on the international market, but its technical level is uneven and can be divided into two stages: one is a machine production plant for potato cultivation, dominated by german grimme, united states of america double l and norwegian tks, which mainly produces medium- and medium-sized seeding kits, has a well-developed hydraulic system and seeding electronic monitoring system, and is highly automated; and the second is a company in italy, the netherlands, japan and other countries, which produces small and medium-sized potato farming tools at a slightly lower price and is suitable for small area potato seeding operations。
(1) spoon (chain) preciserests
A spoonband (chain) precision seeder is one of the most widely used excretion devices in foreign potato sowing machines. It was originally used in the german grimme potato sowing machine, where a dent is taken and placed on the chain (transmitting belt) and used for transmission. Spoon-chained precision seeders affect the seed rate of potatoes and their later production due to such disadvantages as the ease of extracting a dent and chain, the vulnerability of chain teeth on the wheel to broken, and the vulnerability of chain chains to damage the seeding of potatoes/thrusts. Spoon-banded precision dispensers have the advantage of being reliable at work, having good generality and growing precision。
The process of a spoon chain preciserest is shown in figure 1-2, which consists of active chains, passive chains, multiple scavengers, chains, protective shells. Seeding is mounted on a chain, wheel-driven active cycle rotates at work, lifts from bottom to bottom through a chain, picks a dent from a box or chips from the trunk during the lifting process, takes a dent to drive the poach to the top, produces a gravitational force and scavengers to produce only one poach in a pore, thus achieving the purpose of precision seeding by reaching the passive wheel, and takes a pore to plant the pore throwing on the back of the former to take the dent, moving downwards under the protection of the protective shell, and when reaching the bottom, the seeding loses its support, putting it into pre-opened ditches, with its own gravity, to complete the planting process。
H. Buitenwerf et al. Performed mathematical simulations of the process of seeding of potatoes from a spoon-chained precision cutter and used high-speed video technology to validate the impact of the parameters of the tube and the extraction of the dents on the sowing accuracy of potatoes. The test concluded that, in the case of the same parameter, the higher the speed, the better the balance of the rows, and that the influence of the potato shape on the flow properties was not significant。
