Research status and development countermeasures of orchard trencher

Our country has a vast area and rich species.In terms of fruit cultivation alone, the national fruit cultivation area reached 10.7343 million hm2 in 2008.Since our country's fruit production jumped to the first place in the world in 1993, it has been ranked as the world's number one fruit producer for 17 consecutive years.The continuous increase in fruit planting area and the large-scale transfer of rural labor to cities in our country have made our fruit growing industry face huge challenges.According to investigations by relevant personnel, most of our orchards are currently in an unmanaged state. This situation has caused many problems such as low fruit yield and poor fruit quality in our country.In order to ensure the rapid and good development of China's fruit industry, it is necessary to increase investment in orchard construction and management.

    Orchard ditching and fertilization are a strong guarantee for orchards to achieve high yield and stable production.However, most of the ditching and fertilizing work in orchards used to be done by human labor, which was not only inefficient, but also greatly increased labor costs.Therefore, it is of practical significance to study and discuss the development status and trend of orchard fertilization and trenching machinery.

    1The research status of trenchers at home and abroad

    1.1 Overview of the development of foreign trenchers

The development of foreign trenchers has a history of more than 70 years. Countries such as the United States, the former Soviet Union, the United Kingdom, France, Italy and Japan have developed rapidly and formed a series of products [1].Such as the Malletti and Dondi trencher series in Italy, the Ridder trencher series in the Netherlands, and the “Lida” trencher series in Japan [2].The smallest trencher has a power of only a few kilowatts, and the largest power reaches 1100 kW and a mass of 136t. It can dig ditches with a depth of 1.8m and a width of 4.5m.According to the different needs of users, the trencher can be equipped with a variety of working devices, such as bulldozers, chisels, backhoes, cable spreaders, etc.; On more advanced trenchers, high-tech technologies such as hydrostatic transmission, electronic leveling, and automatic power control are widely used.At present, the world's major trencher manufacturers are all in the United States, such as GASE, Charles Machine Works, Burkeen, Vermeer, A.F.Trenchers, RWF Industries, Maxon and other companies have a high reputation in the industry.Foreign trenchers are developing in the direction of specialization, large-scale, energy-saving and intelligence.

1.2 Overview of the development of domestic trencher

    As early as the 1950s, ploughing and ditching have been used in the construction of farmland water conservancy in our country.However, the research and development of other forms of trenchers started late, and generally experienced the development process of plough trenchers, disc trenchers, vertical spiral trenchers and chain trenchers.In the early days, the country mainly relied on the introduction of foreign products to fill the gap in domestic trenchers.For example, in 1975, China's agricultural reclamation system introduced the FLAT series of rotary disc trenchers of the Italian Fiat company for industrial and agricultural construction; in the mid-1980s, the country introduced a small number of trenchers mainly used in agricultural concealed pipe drainage projects, but due to technical performance and economic reasons, these trenchers were gradually eliminated a few years later.At present, there are two main types of domestic trenchers, plow trenchers and rotary trenchers.Among them, rotary trenchers are widely used and have more products.

    1.2.1 Plow plow trencher

    Because of its advantages of simple structure, fast speed, high efficiency and reliable work, plough trencher was introduced for farmland construction in the 1960s.However, due to the shortcomings of bulky structure, high traction resistance, large gaps left by the ditch and cannot be automatically dispersed, and manual repairs are required for the opened ditch, its use is greatly limited.Now some developed countries have eliminated plow trenchers, and other countries are also undergoing a transition from plow trenchers to rotary trenchers.

    1.2.2 Milling cutter disc trencher

    The milling cutter disc trencher belongs to a fast rotating trencher.Because it has the advantages of low traction resistance, strong adaptability, and good operation quality, it is widely used.The main working part of this type of trencher is one or two high-speed rotating discs, and different quantities and specifications of milling cutters and wall cutters are installed symmetrically on both sides of the discs.The trenching section of this trencher is an inverted trapezoid with a wide mouth and a narrow bottom. The depth of the groove is determined by the diameter of the disc, and the width of the groove is adjusted by replacing different milling cutters.

    In 1999, the Agricultural Machinery Bureau of Jiangnan County, Jiangxi Province successfully developed a 1KSH-15 disc trencher based on the characteristics of southern agricultural cash crops and the economic affordability of farmers.The working parts of the machine are installed on the rotary tiller shaft supporting the Dongfeng-12 walking tractor. The working parts have a mass of 33 kg, a trenching depth of 100-200 mm, and a width of 250±20 mm. Adjustable.It has the characteristics of small required power, good soil crushing performance, low soil return volume, and high ditch depth stability.Due to the limitations of ditch depth and ditch width, it has not been widely promoted.

    In 2001, the KX-40 double-disc rotary trencher designed and completed by Zhang Chuanzhong and others was used in conjunction with large and medium-power wheeled tractors. It has the advantages of good maneuverability, light weight, large trenching size, standardized trench type, and uniform soil throwing.The power configuration of the machine is a 30-40 kW wheeled tractor, the trenching size is 500 mm×400 mm×400 mm (ditch surface width × ditch bottom width × ditch depth), the disc has 16 milling cutters on the left and right, and the linear speed of the cutter disc is 11 m/s.At present, the machine is mainly used for the excavation of boundary ditches in well sites and trenching operations in some open places. It is of little use for woodlands and orchards with more complex terrain and small space.In 2008, the Institute of Agricultural Mechanization of Xinjiang Academy of Agricultural Sciences successfully developed the 1KF-35 Orchard ditching and Deep fertilizing Machine.The machine is mainly used for orchard ditching and fertilizing, tree planting and ditching, and can also be used for farmland ditching and ridge crop ditching and fertilizing.The machine has a simple structure, a mass of 260 kg, and the trenching size is: the depth is adjustable from 300-500 mm, the width is 300 mm at the lower mouth and 500 mm at the upper mouth. It is an inverted trapezoidal wheel tractor with a power configuration of 18.5—25.9 kW.After that, they improved the machine and developed a 1K-40 biased orchard trencher. The 1K-40 removed the fertilization device, reducing the height of the whole machine and reducing the quality IS.91.The above two models can better solve the ditching and fertilization operations of some orchards in Xinjiang and the Northern Plains, but it is still too large in most orchards in the south.

    1.2.3 Chain trencher

  Chain trencher is a kind of slow-speed rotary trencher, which is generally suitable for opening narrow and deep ditches.Due to the large depth of soil cut by the chain cutter trencher and the large specific resistance, the trencher has a large resistance and consumes a lot of work. The tractor cannot work at normal working speed. It needs to be equipped with an ultra-low-speed tractor or a tractor with an ultra-low-speed transmission device to operate.The excavation part of the chain trencher is a chain with blades. The teeth cut the soil and bring it to the ground, and then use a horizontal screw conveyor to transport the soil to one or both sides of the ditch.

    In 1992, Xie Jinquan conducted a preliminary study on the working parts of the chain gear trencher.It is pointed out that the specific power (that is, the power consumption per unit cubic working volume) is the main technical performance index of the trencher design.According to the operating requirements of orchard trenching operation, the specific work is less than 0.4 kW'LVM3, and the cutting pitch is calculated to be 3 em, the operating inclination angle is 400, and the specific work of the chain gear is smaller at the linear speed of 0.356m/S.

    In 1998, Yang Yougang and others developed a 1KLQ-80 chain trencher suitable for small working spaces in orchards.The supporting power of the machine is 11 kW, the maximum trench depth and width are 800 mm and 650 mm, and the production efficiency is 125 m/h.The difference between it and other chain trenchers is that the whole machine will walk in the ditch when working, avoiding the problem of insufficient orchard space.However, since the soil working surface is located in front of the working parts, the soil may cause greater collapse under the action of cutting force, machine vibration and its own gravity.After that, in order to solve the stability problem of the machine.The starting acceleration characteristics of the trencher are analyzed, and the role and selection principles of the main design parameters on the stability of the trencher's starting acceleration working conditions are discussed, and good results have been achieved.However, due to the large differences in the soil characteristics of orchards in our country, the machine itself also has the problem of soil landslides during trenching operations.Therefore, the machine has not been well promoted.

    In 2002, Liu Changrong and others modified a chain trencher supporting an 8.8kW walking tractor to meet the needs of ditching and fertilizing vineyards.The machine has a simple structure, is more practical, and requires little power.The trenching depth is 400 mm, the width is 400 mm, the efficiency is 1km/h, and it performs well in the effect test [9, 10].

    In 2009, the 1KF-500 orchard ditching and fertilizing machine developed by Xinjiang Zhongji Agricultural and Animal Husbandry Machinery Company was tested in Aksu Kashgar and other places, and the results showed that all performance indicators met the design requirements.The machine adopts an independent hydraulic system to control the adjustment of the trenching depth, the configuration power requirement is more than 30 kW, the mass of the whole machine is 510 kg, the trenching depth is 300-800 mm, and the width is 200-500 mm.

    1.2.4 Vertical spiral trencher

    In the late 1990s, vertical spiral trenchers began to be valued by scientific research institutions and manufacturers in China, and successively developed the 1KL series and 1KLZ series trenchers.The main working part of the vertical spiral trencher is the cone spiral. When working, the driving force is transmitted to the cone spiral through the deceleration device and the reversing device, and the soil is cut through its rotation to form a cone-shaped groove shape.The design of a vertical spiral trencher needs to consider many factors, but there are only three artificially controlled parameters, namely the forward speed of the machine, the speed of the working parts, and the spiral angle of the cone spiral.Optimizing the design of these three parameters is an effective way to improve the production efficiency of the trencher and reduce the specific power consumption.

    The 1KL-I00 spiral trencher was developed by Northeast Agricultural University. It is mainly used for the excavation of drainage ditches in the process of grass charcoal mining. It can also be used to dig drainage ditches in farmland.The whole machine is equipped with a power of 80.9 kW, a maximum trench depth of 1 m, an inverted trapezoid shape, a maximum upper mouth width of 1200 mm, and a lower mouth width of 340 mm.The wall of the ditch is flat, there is less residual soil in the ditch, and the performance is excellent, which basically meets the requirements of grass charcoal mining.

    The 1KLZ-27 vertical spiral trencher was developed by Kunshan Agricultural Machinery Research Institute.Its simple, novel and unique structure aroused the interest of many farmers at that time, and more than a thousand machines in trial production were well used in Jiangsu and Zhejiang regions.And it meets the set continuous cutting, the cutting angle on the cutting length is constant, the spiral blade “variable lead", and the geometry of the blade meets the requirements of soil axial transportation along the blade [19].

    In 1998, Ou Yinggang and others of South China Agricultural University studied the law of soil destruction under the action of vertical spiral trenchers, determined the best working method of the working parts of the trencher acting on the soil of vegetable fields, and tested the force and power consumption of the vertical spiral trencher on vegetable fields to determine the best combination of factors for the working parts of the trencher.Through the analysis of the working characteristics of the vertical spiral trencher, a set of test devices was developed and experimental research was carried out in the soil trough.

    2 Existing problems

    1) At present, trenchers generally have a narrow adaptation range. Most trenchers are designed only to consider the working environment of general engineering, which is not suitable for orchards, especially mountain orchards.

    2) Many trenchers have the defect of idle power.Especially for small trenchers, the power source and the working parts are often welded into a whole.This reduces the installation process, but causes the idle power of the trencher.

    3) Many trenchers have excessive power consumption; they are prone to intense vibration and deviation when trenching; the tool wears out quickly; and the biased trencher automatically yaws.

    4) Orchard ditching and fertilization requires strong power to ensure, but the narrow working environment of the orchard limits the work of high-power trenching tools.At present, there are many types of trenchers in China, but there is a lack of equipment that can open fertilizing ditches in the hills and mountains of the south, such as orange orchards, lychee Longan orchards, banana orchards, etc.

    3 Development countermeasures

    1) Consider the requirements of the orchard environment for the trencher, break through key technical problems, and enhance the adaptability of the trencher.

    2) Develop different types of working parts for the same power source.Such as trenchers, cultivators, rotary tiller and other agricultural machinery can share a power source.

    3) From the theoretical point of view, combined with the actual situation, focus on the following aspects: first, the principle of trenching and the force analysis of the trenching tool, in order to continuously improve the design and optimize the tool, so that the power consumption and fuel consumption of the trencher are reduced; second, the cause of deviation, first look at whether it is due to the shape of the tool or the angle of installation, and then make corresponding adjustments to design a symmetrical structure to eliminate vibration, deviation and poor straightening performance; third, the material selection of the tool to solve the problem of short life; fourth, for different forms of trenchers, set up yaw devices of different principles, which can be moved by position. .