In most areas of our country, the moisture content of corn seeds at harvest is generally 25% ~ 35%, or even higher, so it can not be threshed directly at harvest, and the method of subsection harvest is generally adopted. The first stage of harvesting refers to the direct collection of corn ears and stalks with bracts or peels after ear picking; The second stage refers to the threshing of corn ears after cooling and drying on the ground or in the field.
Mechanized corn harvesting can be roughly divided into the following forms:
1. Combined harvest:
Using corn combine harvester, ear picking, peeling and ear gathering (or ear picking, peeling and threshing, but the grain humidity should be below 23% at this time) are completed at one time, and at the same time, stem treatment (cutting silage or crushing and returning to the field) is carried out, then the braceless ear is transported to the field, dried and threshed.
Its technological process is three continuous links: ear stripping-straw treatment.
2. Semi-mechanized harvesting
(1) The corn was cut and spread on the ground with a cutting dryer. After a few days of drying, the moisture content of the grain decreased to 20% ~ 22%, and the ears were picked and peeled by machinery or labor, and then transported to the field for drying and threshing. Straw treatment (cutting silage or crushing and returning to the field).
(2) Using a corn ear picker to pick ears in the growing state (called vertical stalk ear picking), then transporting the ears to the field, peeling them with a peeler, drying them in the sun and threshing them; Straw treatment (cutting silage or crushing and returning to the field).
Its technological process is: ear picking-peeling-straw treatment (in three steps).
3. Others
(1) refit the corn header with the grain combine harvester, and complete the operations of ear picking, peeling, (threshing, separating and cleaning) at one time;
(2) The corn is cut by the lawn mower and paved with herringbone strips, and the grain combine with the ear picker picks up the grain and threshes it, and at the same time, it can thresh the straw fields.
The research and production technology of corn harvester abroad has matured. At present, in the United States, Germany, Ukraine, Russia and other western countries, corn harvesting (including grain and straw silage) has basically achieved all mechanized operations. Because its planting method is mostly one season a year, and the moisture content of corn seeds is very low at harvest, most countries adopt the harvesting method of corn ear picking and direct threshing. For example, corn combine harvesters of John Deere Company, Case Company, Meng Le Company and Deutz Company. In the United States, the corn header is mostly replaced on the wheat combine harvester, and the corn is harvested by adjusting the rotation speed and threshing gap of the threshing drum.
In the past twenty years, China has introduced some foreign models, such as the combine harvester of Case Company in the United States, which can pick and thresh corn in one operation. Because of the corn producing areas in northern China, especially the wheat and corn rotation planting areas, the grain moisture content is as high as 35% or more when corn is harvested, and the grain breakage rate is very serious when it is harvested directly by threshing. According to the measurement of 1980 in 10,000 mu square experimental station in Luancheng County, Hebei Province, the average grain crushing rate of 1440 combine harvester of Case Company in the United States was 65,438 when harvesting corn after replacing the corn header. Moreover, this direct threshing harvesting method is not conducive to the after-ripening of corn, which reduces the yield, and the corn straw can not be crushed and returned to the field or recycled. Therefore, this kind of machinery is not suitable for harvesting high-moisture corn in double cropping areas in China.
Comparatively speaking, KCKY-6 corn harvester manufactured by Cumbain combine harvester company in Hellson, Ukraine can combine ear picking, ear stripping and silage, which is suitable for the agronomic requirements in most parts of China. However, due to the huge model, it has poor adaptability to the field road conditions in rural areas of China. The price is expensive, which is inconsistent with the level of China's economic development.
Since 1990s, many units in China have developed more than 60 models of corn harvesters and applied for 64 related patents. From the structural form, it can be summarized as follows:
A. single-row corn harvester
Four-wheeled tractors are mounted on the side or vertically, and the representative models are 4YZF- 1, 4Y 1 18, etc. And most of them are ear-picking roller-type ear-picking mechanisms. Generally equipped with straw crushing device, it can complete corn ear picking, box collecting and straw crushing at one time.
B. Backpack corn harvester
Used in conjunction with 36.8 ~ 48kW (50-65hp) tractors, the picking mechanism of the double-row machine is mostly the picking roller type, which has certain peeling function. In the past, the picking mechanism of the three-row machine was mostly the picking plate, which mainly imitated the harvester technology of the Soviet Union, and now it is widely used for picking ears. This machine can complete corn ear picking, ear gathering and straw crushing at one time.
C. Traction corn harvester
It can be used for tracked or wheeled tractors. The representative model is Fengshou -2 horizontal traction corn harvester. For tractors with power of 40 ~ 55kW (54 ~ 75hp) and above, the ear-picking mechanism is the ear-picking roller type with peeling function. At present, it is rarely used, because its unit is very long and it needs to be cleared manually before operation, which does not meet the requirements of large-scale operation.
D. Multi-row self-propelled corn combine harvester
Representative models are 4YZ-3, 4YF-3 and 4YZ-4. Most of these models are ear-picking plate-type ear-picking mechanisms, equipped with 58.8 ~ 88 kW (80- 120 HP) motors, which can realize the functions of corn ear-picking, cutting table and straw crushing. For example, Fulu brand 4YZ-3 corn combine harvester is characterized in that its main working parts are manufactured by Hellson Kangbain Company of Ukraine with advanced production technology, complete equipment and mature technology. Although its working performance and quality are the same as those of domestic models, its reliability is high and it has been recognized by users. Jinlang brand 4YJL-3 corn combine harvester is characterized by the combined structure of hob, stem pulling roller and ear picking plate, which avoids the phenomenon of weeds winding sticks, reduces the power consumption of ear picking, and has good machine adaptability and harvesting quality. Because of the design of the fruit box that can be opened and poured immediately, its working efficiency has been improved by 30%.
E. corn harvester for harvesting ears and stems
There are two representative models: 4YZ-3 and 4YZ-4. 4YZ-4 corn harvester is designed according to the principle of KCKY-6 corn harvester produced by Kamben Manufacturing Company in Kherson, Ukraine. It is a four-row self-propelled machine with the function of corn peeling. Model 4YZ-3 corn harvester is a three-row self-propelled corn combine harvester with fruit box. This machine can meet the needs of rural roads and small and medium-sized plots in China. This machine can harvest green straw in time and achieve the goal of harvesting both ears and stems.
F. Non-aligned corn harvester technology
This patent was developed by Beijing Peter Yi Electromechanical Technology Application Center on 200 1, and it is a new patented technology of three-chain ear-picking monomer for off-line corn harvester (patent number ZLO12 74995.8). The ear picking mechanism consists of ear picking rollers and left and right ear picking chains. The ear conveying chain, the transmission box and the frame form an independent ear picking unit. The mechanism breaks through the limitation that the traditional ear-picking roller can only form double rows of cutting tables, realizes the layout of multi-row cutting tables and meets the agricultural requirements of self-cleaning. The ear-picking roller ear-picking assembly is especially suitable for harvesting green straw corn. It has the advantages of less ear loss, low impurity content in ear, uninterrupted stalk and fast running speed. When harvesting summer corn in the late stage of wax ripening and early stage of yellow ripening in North China, the quality of ear-picking drum mechanism is better than that of ear-picking plate-pulling drum mechanism. The two ear picking chains of the three-chain ear picking monomer are distributed in front of the ear picking roller in a V shape, so that the corn stalks on the front, left and right sides can be picked into the ear picking roller, thus achieving the purpose that the cutting range is not limited by the row spacing.
This misaligned corn harvester technology can also be applied to the above various forms of corn harvesters.
Fukang brand corn harvester, Lejin corn harvester and Nongken brand corn harvester all adopt this form.
Compared with developed countries such as Europe and America, China's corn planting has the following characteristics: 1, small planting area, 2, uneven row spacing of corn planting, and 3, high water content of corn at harvest. Therefore, the design requirements of corn harvesting machinery in China are different from those in developed countries such as Europe and America. The following points should be achieved:
The corn harvester designed by 1. should be very flexible in the process of operation, transportation and grain unloading, and suitable for field use in small plots.
2. In view of the low cultural quality of farmers at present, the corn harvester developed should be as simple and convenient as possible to operate and maintain.
3. The designed corn harvester should be able to harvest in different branches. Otherwise, it will not only affect the harvest quality, but also reduce the production efficiency. It has affected the enthusiasm of farmers to buy corn harvesters.
4. The designed corn harvester must be able to harvest high-moisture corn (the water content of seeds is about 40%), and the crushing rate of ears and seeds shall not exceed the national standard.
In order to prevent mildew, there should not be too many stems and leaves in the harvested corn ear.
6, the unit should have good strength and stiffness, can adapt to the bad road.
7. At the same time, the harvester can return the straw to the field with high quality.
8. The unit has high reliability.
Technical indicators and typical effects of demonstration application
(-) Economic effects of production and application.
The technical performance index to be achieved by that corn harvest in production and application are as follows:
Net harvest rate ≥82%, ear loss rate < 3%, grain breakage rate < 1%, ear miscellaneous rate < 5%,
The qualified rate of chopped straw returning to the field is more than 95%, the stick height is less than < 100mm, and the use reliability is more than 90%.
Under the condition of reaching the above technical indexes, the productivity of corn harvester is the key factor to determine its technical and economic indexes. Generally, mechanized harvesting such as corn picking, peeling, ear picking and straw returning is completed, and the working capital per mu is 40 ~ 60 yuan. The productivity of single-row harvester is 2 ~ 3 mu/hour, that of double-row harvester is 4 ~ 6 mu/hour, that of three-row harvester is 8 ~ 10 mu/hour and that of four-row harvester is about 12 mu/hour. The production cycle of a harvest season is about 15 ~ 25 days. Calculated by the half efficiency of the machine, the investment can be recovered in about 2 ~ 3 years.
(2) Analysis of typical application effect
Take the 4YB-3 three-row corn harvester straw recovery model produced by Beijing Zhongken Import & Export Co., Ltd. and used with Tianjin Tieniu 804 tractor as an example. In 2006, the maximum working area of a single machine was more than 2000 mu, and the average working area was 1000 mu. According to the operating cost of 60 yuan per mu, the machine cost can be recovered in about two years, which is greater than the economic benefit of wheat combine harvester. It can be seen that it is of investment value and good economic benefits for agricultural machinery households to purchase corn harvesters for technical operation services.
Key points and matters needing attention in technical implementation
(-) technical specifications
In order to ensure the harvest quality of corn fruit and the effect of straw treatment, and reduce the crushing rate of ears and seeds, the qualified rate of straw returning to field, the qualified rate of root stubble and the requirements of straw silage, corn harvest should meet the following requirements:
1. The harvesting of corn silage with straw should be carried out at a suitable time, and the harvesting operation should be carried out as far as possible before the corn fruit is just ripe and the straw has not dried and turned yellow (at this time, the nutritional components and moisture of straw are beneficial to silage).
2. The harvest of corn with straw returning to the field should be carried out at intervals of 3-5 days after the fruits and oranges are ripe as far as possible, so that the corn seeds are fuller and the moisture content of the fruit draft is beneficial to peeling. When the straw becomes Huang Shi, the reduction of moisture is more conducive to crushing the straw, which can relatively reduce the power loss.
3. According to the plot size, planting row spacing and operation quality requirements, select appropriate machines and tools, formulate specific harvesting operation routes before operation, and prepare for manual harvesting according to the characteristics of machines and tools.
(2) Precautions
1. Before the harvest 10 ~ 15 days, the lodging degree, planting density and row spacing, ear drooping degree and minimum heading height should be investigated in the field. Corn, and should make an operation plan in advance;
2. Level the furrows and ridges in the field 3 ~ 5 days in advance, and install signs for inconspicuous obstacles such as wells and poles to facilitate safe operation;
3. Before the operation, try to harvest, adjust the machines and tools, and then put them into formal operation after they meet the agronomic requirements.
4. Before the operation, properly adjust the gap between the pick-up roller (or the pick-up plate) to reduce the grain breakage; When operating, pay attention to the fluency in the process of lifting ears to avoid getting stuck or blocked; Observe the fullness of the ear box at any time, and dump the ear in time to avoid overflowing after the fruit is full or blocking when unloading the grain;
5. Correctly adjust the working height of the straw returning machine, ensure that the stubble height is less than 10cm, and avoid digging damage of the returning tool;
6. If stubble-cleaning machine is installed, the depth of stubble-cleaning machine should be ensured, and the stubble-cleaning depth should be consistent to ensure the operation quality.
General principles of technical support machines and tools
1. 12 ~ 18 horsepower tractor single-row corn combine harvester is generally only suitable for corn ear picking, ear lifting, ear gathering and straw returning.
2. The corn combine harvester matched with a tractor with 50-60 horsepower can harvest 2 rows (or 3 rows) at a time, and complete the operations such as ear picking, transportation, stabilization, and straw returning to the field; When it is matched with a tractor with more than 65 horsepower, it can not only complete the above operations, but also complete the stubble breaking operation;
3. Most corn seeders in China are 2 rows, 3 rows and 6 rows, and corn combine harvesters need to harvest in opposite rows. Therefore, two-row and three-row corn combine harvesters have better adaptability than single-row and four-row corn combine harvesters.
4. According to the power reserve of the tractor supporting the corn harvester, install the straw returning machine with corresponding sub-width and a certain number of blades.
(3) General requirements for machine operation
1. During transportation, the corn combine harvester and straw returning device should be lifted to the transportation state. When the gradient of the forward direction is greater than 15, it is not allowed to shift gears in the middle to ensure transportation safety;
2. During the operation, observe the operation quality at any time. If there is a problem with the operation quality or the machine has a fault, the engine must be turned off before adjustment and troubleshooting can be carried out;
3. Corn harvesters are not suitable for plots with a ground slope greater than 8;
4 corn harvester turning speed shall not exceed 3 ~ 4 km/h. ..
The Ministry of Agriculture has listed the development of corn harvesting mechanization as an important project in the Tenth Five-Year Plan. But the future corn harvesters will not only aim at picking ears, but some special harvesters will occupy a certain proportion. Such as corn combine harvester for silage and waxy corn harvester. Among them, the development of corn combine harvester for silage has begun. .
It is certain that the high-performance self-propelled corn harvester is the main model to realize the mechanization of corn harvesting in China. However, we predict that according to the actual situation in China, the performance-price ratio of the backpack harvester used with tractors is higher than that of the self-propelled harvester. Non-aligned backpack harvester will become a bright spot because of its high adaptability and shift productivity. In recent years, the knapsack misaligned corn harvester, which is suitable for China's national conditions, has been greatly developed with simple structure, low cost and wide adaptability.