花生收獲機(jī)設(shè)計(jì)與仿真【三維PROE】
花生收獲機(jī)設(shè)計(jì)與仿真【三維PROE】,三維PROE,花生,收獲,設(shè)計(jì),仿真,三維,PROE
Design principle and analyses of the motion characteristics of 4H-2 type peanut harvester
Abstract
The structure, working principle and design of main parts of the 4H-2 type peanut harvester were described and analyzed, and the kinematics model of the main work parts was founded. On the basis of the optimized structure, the representative tracks of the work parts were described by means of Visual Basic and SPSS software and the machine function characteristics. The theoretical foundation has been provided for further study of this kind of machines.
Key words: Peanut harvester; design principle; motion characteristics
Biography: Shang Shuqi(1958-), born in Qingzhou City, Shandong Province, Professor, Head of Engineering School of Laiyang Agricultural University, Shandong Province 265200, China. Majored in design and performance test of agricultural machinery. Email:sqshang@lyac.edu.cn
1 Introduction
The peanut is one of the main oil plants in the world, which is only inferior to soybean but ranks the second for oil production and international trade[1,2]. For a long time, the planting, harvesting and processing of peanut were mostly completed by manual work. It is a piece of labored work with low efficiency, which affects the peanut production seriously. Especially in the last few years, as the transferring surplus rural labors to urban areas, the contradiction of each link of peanut production is more intensifying, the mechanization of the peanut production becomes particularly important.
It has been a long time for researching and developing the peanut harvesters in developed countries, it is a typical representative that the LP-2 type peanut harvester and peanut combine harvester of "Courtesy lf Lilli ston Mfg. Co." in the United States and PH-2 type peanut harvester of Michigan in Netherlands[3]. The development of peanut harvester in China is later than that in developed countries, perhaps the beginning of the 1960s. Since the 1970s, many representative mimic peanut harvesters were introduced into China such as the Dongfeng 69 type, 4HW-800 type and 4H-150 type peanut harvester etc.[4]. These products bring convenience for harvesting peanut, but the structure of all current harvesters adopted the two steps of harvest principle—scoop and separating chain combine together. These machines have to match with the medium-big power tractors. It is not only complex in structure, higher manufacturing costs, more power consumption, poor reliability, but also higher harvesting loss rate, peanut vines spread disorderly, and inconvenient for manual collection. It is not suitable for the current requirement of peanut harvesting and results in that the harvesting of peanut is almost completed by manual work at present. The mechanization level of peanut harvesting affected the development of the peanut production seriously.
With the environment deterioration, at sowing-season in spring or autumn, the phenomenon of dry and little rainfall appears. The peanut production suffered from the weather. It had led to
adopting technique of plastic film covering(Figure 1 shows its section structure). This new technique will play an important role in keeping the moisture of soil, increasing ground temperature, and reducing management in seedling period, and then increasing the output of peanut. The peanut seeding-machine with many functions has already applied in large-scale areas, but the quantity of the film remains is increased, which influences the following work[5-9].
Fig.1 Profile of peanut covering plastic film and seeding beds[8]
For solving the problems mentioned above, a new type of peanut harvester with new working principle and structure was invented, which has already come to the market. The harvester has already acquired the petty patent now (patent number: ZL 01221476.0), and patent for invention ( patent number: 99124518.0) has been investigating in substance.
2 Structure design of the peanut harvester
2.1 Analysis of the whole machine structure
4H-2 type peanut harvester combines with the advanced method of planting and agricultural requirement, which can harvest two rows at one working stroke. It matches with the 8.8～13.0 kW small four-wheel tractors. 4H-2 type peanut harvester is composed of gaging wheel, transmission shaft, eccentric wheel, pitman, long rocker-arm, erect axis, harvesting parts, long pitman, rocker-arm, mounting device and frame etc. The figure 2 shows its structure.
1.gaging wheel 2.joint coupling 3.transmission shaft 4.erect axis 5.long rocker-arm 6.long pitman 7.mounting device 8.rocker-arm 9.erect axis 10.harvester part 11.eccentric wheel 12.pitman 13.harvest part 14.frame
Fig.2 Diagram of peanut harvester
The driving power needed of the work parts of 4H-2 type peanut harvester comes from the PTO of tractor. When the machine with tractor goes forward, the PTO drives eccentric wheel 11 pass through joint coupling 2 and transmission shaft 3. Then eccentric wheel 11 drives long rocker-arm 5 to move pass through pitman 12. As erect axis 4 and harvest parts 13 are made together, rocker 8 with long pitman 6 and long rocker-arm 5 constitute an inverse parallelogram mechanism, therefore harvest parts 10 and 13 swing with erect axis 4 and 9 with the same frequency and angle but contrary direction. The working process is: the scoops 10 and 13 digging the peanut out and
moving the peanut backward, while the lengthways grids continuously make the fanlike swing, and then break the admixture of soil and peanuts. By this movement the heavy soil sinks down via the grids, and the lighter peanut moves up, so that peanut is separated from soil well. The peanut is moving rearward continuously, finally even laying on the excavated ground, so it is convenient for manual collection.
2.2 Main technique parameters
The table 1 shows the main technique parameters of 4H-2 type peanut harvester.
Table 1 Main technique parameters
Power requirement
8.8～13.0 kW small four-wheeled tractor
Productivity/hm2·h-1
0.10～0.13
Losing rate of nuts
≤2%
Containing rate of soil in peanut
(by quantity calculation)
<5%
Broken rate of nuts
<1%
Picked rate of nuts by mechanisms
<3.5%
Overall size (L×W×H mm)/mm3
1280×l180×780
Net weight/kg
158
3 Design of main working parts
3.1 Design of the transmission parts
For overcoming the weakness of the traditional peanut harvesters mentioned in this paper, the 4H-2 type peanut harvester has been invented with a new structure and principle. Its scoops and separating parts have been combined together that can reduce the power consumption, the size of the machine and harvesting loss. The transmission and control devices are designed for transmitting power efficiently and adjust conveniently. In order to match the tractor of 8.8 kW, the power input shaft 1 of 4H-2 type peanut harvester is located in flank of left. The inverse parallelogram mechanism is the remarkable characteristics of this machine. It swings both scoops with the same angle but opposite direction. The side forces acted on two scoop frames are balanced each other. The stability of the machine is ensured and the investment of manufacturing is reduced greatly, which is benefited to large-scale production and popularization of the harvesters.
3.2 Design of scoop frames
When the harvester working in field with dense peanut stalks, the flowing channel of the peanut is easily jammed, resulting in that the working resistance is increasing, and peanut separating is ineffective, even the harvester cannot continue to work. For resolving this problem, the structure of half open arm " " has been created for the scoop frame (show in the figure 3) and the bottom is the scoop. As there are tow scoops, the form respectively is " " and " ", tow of them forming the " " channel, which makes the peanut stalks easily to pass it.
Fig.3 Diagram of scoop frames
3.3 Design of the transmission with V-belt
According to the different circumstances of the fields, the swing frequency of harvesting parts should be adjusted and changed. For this reason, the one step V-belt transmission has been adopted for changing the swing frequency by replacing the V-belt pulleys. After optimizing the four-bar linkage and the size of the belt pulleys, the frequencies and the range of swing are more reasonable.
3.4 Design of the grid shape
If the sectional shape of grid is round, the connection point of grids with scoop will be broken easily after working. In order to increase its anti-bent intensity, the " flat" rectangle sectional grids have been selected out and application after making theoretical design and experimental analysis (the figure 4 shows its structure).
Fig.4 Diagram of grid shape
4 Equation of kinematics
4.1 Theoretical analysis of the main parts
Figure 5 shows the structure of transmission parts of 4H-2 type peanut harvesters. In this figure, No.3 is transmission shaft and No.11 is eccentric wheel, the AE and BD respectively indicate the rocker-arm 5 and 8, the CD and EF indicate pitman 6 and 12 respectively, the A and B is respectively erect axes 4 and 9 (reference Figure 2).
Fig.5 Diagram of transmission parts structure
Fig.6 Simplification diagram of movement[9,10]
When 4H-2 type peanut harvester working, transmission shaft 3 drives eccentric wheel 11 running. As the track of point E is a space arc, but its length is far shorter than AE rocker' s in XOY coordinate plane (<10%), so that E point track may approximately be the straight line movement which is in the XOY coordinate plane. The figure 6 shows the movement form. O′F stands for eccentricity and EF stands for pitman 12. As O′F=R,EF=L, then the track of E point may approximate be considered a straight line OE. So the rectangular system of axis can be established to find the kinematics equation. Turn O to be the origin of coordinates, the direction of OO′ is the positive direction of X axes. According to the known condition, at beginning t= 0,F is in the place for F′,E is in the place for O. Obviously OF′+O′F′=L+R. At any time E point coordinates is:
According to the crank rocker structure, K is usually among 1/6～1/4. By the binomial equation, then
As the other numbers are much small from the third number, so all of them are ignored.
Videlicet: , then E point kinematics equation approximately is:
The motion characteristics of inverse parallelogram mechanism ABCD depends on the track of point E. The figure 7 shows the structure. A and B stand for erect axes 4 and 9 respectively, AE and BD are respectively rocker 5 and 8,CD is pitman 6. If A is at zero (0, 0). The direction of AX is the positive direction of polar axes.AE=L1. Then A (erect axis) angular velocity equation approximate is:
Fig.7 Schematic of inverse parallelogram mechanism
4.2 Kinematics equation of the harvest parts
As the figure 8 shows, when 4H-2 type peanut harvester is static to the ground relatively, any point of swing grid AH motion as horizontal and fan-shape reciprocating movement, around its erect axis. When working, the movement of any point of swing grid AH is composed of the swing motion of erect axis and moving of tractor. Because of the swing velocity of erect axis is different, the motion track is not the same, but there is certain regulation. Take the farthest point H of swing grid, its relatively static equation is:
Its relatively kinematics equation is:
On the basis of optimum parameter, the track of the farthest point H of swing grid has been gotten by making use of the Visual Basic and SPSS software (Shows in the figure 9).
Fig.8 Diagram of velocity synthesis
Fig.9 Relatively kinematics track of H point
5 Function characteristics of the harvester
The swing-digging principle and the inverse parallelogram mechanism have been successfully created and applied to 4H-2 type peanut harvester. It had broken the traditional way which is scoop and separate chain to combine together for harvesting.
(1) 4H-2 type peanut harvester should be matched with the small four-wheel tractors which are very universal. Its design is reasonable, with reliable working, steady function, convenient adjustment, higher adaptability, and this machine can work in various fields and harvest all kinds of peanut.
(2) The swing-digging principle had been created for merging scoop and separator together. That has successfully realized the work of digging and separating peanut by one set of part, and simplified the working procedure. The two harvest parts were used through inverse parallelogram mechanism to transfer power, turning them by the same angle for swing but opposite direction, making the two sides force acted on scoop frames balanced each other, the operation stability of it is ensured, the resistance and the power consumption have been reduced.
(3) In harvesting process, plastic film was not broken and easy collected with the peanut stalks.
There is none leavings of them on the ground.
(4) As created the swing-digging principle, the whole resistance and the power consumption of the harvester have been reduced. By means of the swing function, the soil with heavy specific gravity sinking passes through the grids, and the peanut with lighter specific gravity moves up, so that the loss rate of peanut was reduced remarkably.
(5) The various working and performance indexes of the machine are superior to the similar type of peanut harvesters, and productivity of it was higher, loss rate lower, the economic benefit remarkable.
4H-2 type peanut harvester is the new typical agricultural implement for the small scale farms of China and more suitable for Chinese peanut production. This harvester has the simpler structure and lower price. Its various performance indexes are superior to the Standard of technique indexes for peanut harvesting in China. It can bring more economic benefit to the customers. After application and extension to peanut production, the 4H-2 type peanut harvesters have won broad praise from the society. This patent achievement indicates fully that the design and principle of 4H-2 type peanut harvesters has reached a new high level.
References
[1] Duan Shufen, Hou Wenguang. The world peanut production and the trade outlook[J]. Chinese agriculture bulletin,1990,6(2):21-25.
[2] Tao Shouxiang. The present condition and outlook of peanut high yield in Shandong province[J]. Peanut science and technology,1993,2:26-29.
[3] Chen Chuanqiang. The broadcast lecture of the mechanization of peanut technique production[R]. The agriculture machinery extension center of Shandong province,2000.
[4] Chinese agriculture movie &television center. How many peanut harvesters[N]. 2002-10-15.
[5] The comprehensive mechanization technique of peanut production. The agricultural technique extension center of Shandong province,1999.
[6] Hao Ming, et al. Peanut production machinery[M]. The publishing house of Hebei province,1981,81-90.
[7] Hua Fagai. Cover-film-planting is the new path to boost peanut production [N]. Fujian agricultural technology, 2000,4:12-14.
[8] Sun Yanhao. The peanut production & cultivation. The gold shield publishing house,1991,61-80.
[9] Peanut Institute of Shandong province. Peanut [ M ]. Jinan: Science &Technique Publishing House of Shandong Province,1982,46-52.
[10] Nanjing engineering college & Xian transportation university. Theories of mechanics (the second version) [M]. Higher Education Publishing House, 1985, 112 - 210.
4H-2型花生收獲機(jī)的設(shè)計(jì)原理及運(yùn)動(dòng)特性分析
摘要
本文主要描述和分析了4H-2型花生收獲機(jī)的結(jié)構(gòu)、工作原理和主要部件的設(shè)計(jì)，并對(duì)其主要的工作部件建立了運(yùn)動(dòng)學(xué)模型。在結(jié)構(gòu)最優(yōu)化的基礎(chǔ)上,利用VB編程和SPSS軟件描繪出了工作部件的代表性軌跡;并簡(jiǎn)述了其性能特點(diǎn),為今后同類型花生收獲機(jī)的研究提供了理論基礎(chǔ)。
關(guān)鍵詞：花生收獲機(jī)；設(shè)計(jì)原理；運(yùn)動(dòng)特性
1 引言
花生是世界上的主要的油料植物，它僅次于大豆，并在油料生產(chǎn)和國(guó)際貿(mào)易中排名第二.長(zhǎng)期以來(lái)，花生的種植、收獲和加工絕大部分工作由手工作業(yè)完成，它是一種效率低下的工作，并且嚴(yán)重影響了花生的生產(chǎn)產(chǎn)量。尤其是近幾年，隨著農(nóng)村剩余勞動(dòng)力向城市地區(qū)的轉(zhuǎn)移，花生生產(chǎn)中的各個(gè)環(huán)節(jié)的矛盾更加激化，在此過(guò)程中的機(jī)械化就顯得尤為重要。
在發(fā)達(dá)國(guó)家中對(duì)于花生收獲機(jī)的研究和開發(fā)已有很長(zhǎng)的時(shí)間了，典型的代表就是美國(guó)的LP- 2型花生收獲機(jī)和Courtesy lf Lilli ston制造公司的花生聯(lián)合收獲機(jī)以及荷蘭密歇根州的PH- 2型花生收獲機(jī)?；ㄉ斋@機(jī)在中國(guó)的發(fā)展要晚于發(fā)達(dá)國(guó)家，大致從 20世紀(jì)60年代開始。70年代以來(lái)，許多具有代表性的仿造的花生收獲機(jī)被引進(jìn)中國(guó)，如東風(fēng)69型，4HW -800型和4H- 150型等。這些產(chǎn)品對(duì)于花生收獲雖然帶來(lái)了便利性，但目前所有收獲機(jī)的結(jié)構(gòu)均采用了兩步收獲方式，即挖掘鏟與分離鏈相配合。這些機(jī)器必須配合大中馬力的拖拉機(jī)。這樣以來(lái)不僅結(jié)構(gòu)復(fù)雜、制造成本較高、耗電多、可靠性差，而且造成很高的收獲損失率，使花生藤蔓延無(wú)序，不方便手工收集。它不適合當(dāng)代的花生收獲要求，并導(dǎo)致了目前的花生收獲幾乎都是由手工作業(yè)完成?；ㄉ斋@的機(jī)械化程度嚴(yán)重影響了花生生產(chǎn)的發(fā)展。
隨著環(huán)境的惡化，在春季或秋季的播種季節(jié)，出現(xiàn)了干旱或降雨量減少的現(xiàn)象?；ㄉ纳a(chǎn)受到了這種惡劣天氣的影響，進(jìn)而產(chǎn)生了采用塑料薄膜覆蓋的技術(shù)（圖1顯示了其部分結(jié)構(gòu)）。這種新技術(shù)在保持土壤水分，增加地面溫度，減少幼苗期的管理，以及增加花生的產(chǎn)量方面都發(fā)揮了重要作用。多功能花生播種機(jī)在大片地區(qū)已經(jīng)應(yīng)用，隨之薄膜的數(shù)量仍然增加，繼而影響接下來(lái)的工作。
圖1 花生覆蓋塑料薄膜和播種床的簡(jiǎn)介
為了解決上面提到的問(wèn)題，一種具有新型工作原理和結(jié)構(gòu)的花生收獲機(jī)已被發(fā)明，并且已經(jīng)投入到了市場(chǎng)。該收獲機(jī)現(xiàn)在已經(jīng)取得了小型專利（專利號(hào)：ZL01221476.0），并且該專利（專利號(hào)：99124518.0）也基本上一直處在調(diào)查研究中。
2 花生收獲機(jī)的結(jié)構(gòu)設(shè)計(jì)
2.1 整機(jī)結(jié)構(gòu)的分析
4H-2型花生收獲機(jī)結(jié)合了種植和農(nóng)業(yè)需求的先進(jìn)方法，在一個(gè)工作行程中它可以收獲兩行。它配備了8.8?13.0千瓦的小四輪拖拉機(jī)。4H-2型花生收獲機(jī)是由量具輪、傳動(dòng)軸、偏心輪、連桿、長(zhǎng)搖臂、直立軸、收獲部分、長(zhǎng)連桿、搖臂以及安裝設(shè)備和機(jī)架等部分組成。圖2展示了它的結(jié)構(gòu)。
1量具輪 2聯(lián)軸器 3傳動(dòng)軸 4直立軸 5長(zhǎng)搖臂 6長(zhǎng)連桿 7安裝裝置 8搖臂 9直立軸 10收獲機(jī)部分 11偏心輪 12連桿 13收獲部分 14機(jī)架
圖2 花生收獲機(jī)示意圖
4H -2型花生收獲機(jī)工作部件的驅(qū)動(dòng)力來(lái)自于拖拉機(jī)的動(dòng)力輸出。當(dāng)本機(jī)與拖拉機(jī)前進(jìn)時(shí)，動(dòng)力輸出軸通過(guò)聯(lián)軸器2和傳動(dòng)軸3驅(qū)動(dòng)偏心輪11運(yùn)動(dòng)。然后，偏心輪11通過(guò)連桿12驅(qū)動(dòng)長(zhǎng)搖臂5運(yùn)動(dòng)。由于直立軸4和收獲部分13做在一起，搖臂8和長(zhǎng)連桿6及長(zhǎng)搖臂5構(gòu)成反平行四邊形機(jī)構(gòu)，因此收獲部分10和13隨著直立軸4和9以相同的頻率和角度但相反的方向擺動(dòng)。其工作過(guò)程是：挖掘鏟10和13挖出花生并使其向后移動(dòng)，而縱向網(wǎng)格連續(xù)做擺動(dòng)，迫使土壤和花生分開。通過(guò)這種運(yùn)動(dòng)，重的土壤通過(guò)網(wǎng)格沉落，而較輕的花生向上移動(dòng)，從而使花生與土壤分離良好。花生不斷向后移動(dòng)，最后平鋪在挖開的地上，這樣就可以方便人工收集了。表1展示了4H-2型花生收獲機(jī)的主要技術(shù)參數(shù)。
表1主要技術(shù)參數(shù)
功率要求
8.8?13.0千瓦小四輪拖拉機(jī)
生產(chǎn)力/萬(wàn)株每小時(shí)
0.10?0.13
花生損失率
≤2％
土壤中花生含有率（按數(shù)量計(jì)算）
<5％
花生破碎率
<1％
花生拾取率
<3.5％
外形尺寸（長(zhǎng)×寬×高mm）/ mm3
1280×L180×780
凈重/千克
158
3 主要工作部件的設(shè)計(jì)
3.1 機(jī)械傳動(dòng)部件的設(shè)計(jì)
為了克服在本文中提到的傳統(tǒng)花生收獲機(jī)的缺點(diǎn)，一種具有新型結(jié)構(gòu)和工作原理的4H-2型花生收獲機(jī)已被發(fā)明。它的挖掘鏟和分離部分結(jié)合在一起，能夠降低能量消耗、設(shè)備的大小和收獲損失。它的傳動(dòng)與控制機(jī)構(gòu)是為高效率傳送功率和方便調(diào)整而設(shè)計(jì)的。為了匹配8.8千瓦的拖拉機(jī)，4H-2型花生收獲機(jī)的動(dòng)力輸入軸1位于左側(cè)側(cè)翼。反平行四邊形機(jī)構(gòu)是本機(jī)的顯著特點(diǎn)，它使挖掘鏟同角度反方向的擺動(dòng)。兩個(gè)挖掘鏟所產(chǎn)生的側(cè)向力互相平衡，這樣機(jī)器的穩(wěn)定性得到了保證，收獲機(jī)大規(guī)模的生產(chǎn)與廣泛的普及將使生產(chǎn)的投資也大為減少。
3.2 挖掘鏟機(jī)架的設(shè)計(jì)
當(dāng)收獲機(jī)在稠密花生地工作時(shí)，花生的運(yùn)送通道很容易被輕易卡住，導(dǎo)致工作阻力增加，花生分離效果欠佳，甚至是收獲機(jī)無(wú)法繼續(xù)工作。為了解決這個(gè)問(wèn)題，半開放機(jī)械臂已為挖掘鏟機(jī)架而設(shè)計(jì)（如圖3所示），其底部就是挖掘鏟。正因?yàn)樗袃蓚€(gè)挖掘鏟，它的形式分別
是什么和什么，形成了運(yùn)送通道，這就使得花生秸稈很容易通過(guò)。
圖3 挖掘鏟機(jī)架示意圖
3.3 V形皮帶傳送的設(shè)計(jì)
根據(jù)不同情況的土地，應(yīng)該調(diào)整和改變收獲部分的擺動(dòng)頻率。出于這個(gè)原因，通過(guò)替換V型皮帶輪而改變擺動(dòng)頻率的V型帶傳送機(jī)構(gòu)已被采用。在優(yōu)化四連桿機(jī)構(gòu)和皮帶輪的大小之后，擺動(dòng)的頻率和范圍更加合理。
3.4 網(wǎng)格狀的設(shè)計(jì)
如果網(wǎng)格的截面形狀為圓形，那么和挖掘鏟的連接點(diǎn)在工作之后則很容易被折斷。為了提高其抗彎曲強(qiáng)度，在理論設(shè)計(jì)和實(shí)驗(yàn)分析（如圖4示結(jié)構(gòu)）后，“平坦”的矩形截面網(wǎng)格已被采取。
圖4 網(wǎng)格形狀圖
4運(yùn)動(dòng)學(xué)方程
4.1 主要部分的理論分析
圖5表明了4H-2型花生收獲機(jī)的傳動(dòng)部分結(jié)構(gòu)。在該圖中，3號(hào)是傳動(dòng)軸，11號(hào)是偏心輪，AE和BD分別表示搖桿臂5和8，CD和EF分別表示連桿6和12，A和B分別表示豎立軸4和9（參照?qǐng)D2）。
圖5 傳動(dòng)部分結(jié)構(gòu)示意圖
圖6 運(yùn)動(dòng)簡(jiǎn)化圖
當(dāng)4H-2型花生收獲機(jī)工作時(shí)，傳動(dòng)軸3驅(qū)動(dòng)偏心輪11運(yùn)動(dòng)。由于E點(diǎn)的軌跡是一個(gè)空間圓弧，但其長(zhǎng)度在XOY坐標(biāo)平面中遠(yuǎn)遠(yuǎn)比AE搖桿的軌跡圓弧短（<10％），所以在XOY坐標(biāo)平面中E點(diǎn)軌跡大致是直線運(yùn)動(dòng)。圖6表示出了其運(yùn)動(dòng)的形式。O'F代表偏心距和EF代表連桿12。由于O'F= R，EF= L，則E點(diǎn)軌道可近似被視為一條直線OE。根據(jù)軸直角性可以用來(lái)建立運(yùn)動(dòng)學(xué)方程。以O(shè)點(diǎn)為坐標(biāo)原點(diǎn)，以O(shè)O'為X軸的正方向。根據(jù)已知條件，在開始t = 0時(shí)，F(xiàn)是在F'的地方，E在原點(diǎn)O的地方。顯然OF'+O'F'= L+R。在任何時(shí)間E點(diǎn)坐標(biāo)為：
假定,,那么
根據(jù)曲柄搖桿結(jié)構(gòu)，K通常取1/6?1/4。由二項(xiàng)式公式，那么
從第三位開始的其他數(shù)字小得多，所以忽略不計(jì)。
即：，則E點(diǎn)的運(yùn)動(dòng)學(xué)方程近似為：
反平行四邊形機(jī)構(gòu)ABCD的運(yùn)動(dòng)特性取決于E點(diǎn)的軌跡，圖7表示了其結(jié)構(gòu)。A和B分別代表直立軸4和9，AE和BD分別代表?yè)u桿5和8，CD為連桿6。如果A在零（0，0），AX方向是坐標(biāo)軸的正方向，AE= L1，那么A（直立軸）角速度方程近似為：
圖7 反平行四邊形機(jī)構(gòu)示意圖
4.2 收獲部分的運(yùn)動(dòng)學(xué)方程
如圖8所示，當(dāng)4H-2型花生收獲機(jī)相對(duì)地面靜止時(shí)，擺動(dòng)網(wǎng)格AH上任意點(diǎn)都繞其豎直軸線做水平和扇形往復(fù)運(yùn)動(dòng)。工作時(shí)，擺動(dòng)網(wǎng)格上任意點(diǎn)的運(yùn)動(dòng)可分為繞其軸線的擺動(dòng)和隨拖拉機(jī)的前行。正是因?yàn)樨Q直軸的擺動(dòng)速度是不同的，運(yùn)動(dòng)軌跡也不一樣，但它有確定的規(guī)律。以擺動(dòng)網(wǎng)格的最遠(yuǎn)點(diǎn)H為例，其相對(duì)靜態(tài)的方程為：
其相對(duì)運(yùn)動(dòng)學(xué)方程為：
在最優(yōu)參數(shù)的基礎(chǔ)上，擺動(dòng)網(wǎng)格最遠(yuǎn)點(diǎn)H的軌跡已經(jīng)利用Visual Basic和SPSS統(tǒng)計(jì)軟件得到（在圖9所示）。
圖8 速度合成示意圖
圖9 點(diǎn)H相對(duì)運(yùn)動(dòng)軌跡
5 收獲機(jī)的功能特性
4H-2型花生收獲機(jī)成功創(chuàng)立并應(yīng)用了擺動(dòng)挖掘原理和反平行四邊形機(jī)構(gòu)，它打破了依靠挖掘鏟和獨(dú)立鏈相結(jié)合在一起收獲的傳統(tǒng)方式。
（1）4H-2型花生收獲機(jī)與常見(jiàn)的小四輪拖拉機(jī)相結(jié)合。這臺(tái)機(jī)器設(shè)計(jì)合理、工作可靠、性能穩(wěn)定、調(diào)整方便、適應(yīng)性高，可以在多樣的農(nóng)田里工作，收獲各種品種的花生。
（2）挖掘鏟和分離器相結(jié)合成為了擺動(dòng)挖掘的原理。通過(guò)這一套裝置已經(jīng)成功實(shí)現(xiàn)了花生挖掘和分離的工作，并且簡(jiǎn)化了工作程序。通過(guò)反平行四邊形機(jī)構(gòu)，兩個(gè)收獲部分傳遞動(dòng)力，驅(qū)使他們以相同角度但相反方向來(lái)進(jìn)行擺動(dòng)，使作用在挖掘鏟兩側(cè)的力互相平衡，這樣確保了操作的穩(wěn)定性，其運(yùn)動(dòng)阻力和功率消耗也被降低了。
（3）在收獲的過(guò)程中，塑料薄膜不被破壞，容易隨同花生秸稈一起收集，且在地面上沒(méi)有殘留。
（4）由于創(chuàng)立了擺動(dòng)挖掘原理，收獲機(jī)的整體阻力和功率消耗也降低了。由于這種擺動(dòng)功能，具有重量大的土壤通過(guò)網(wǎng)格下沉，重量輕的花生向上移動(dòng)，從而使花生的損失率顯著降低。
（5）花生收獲機(jī)的各種工作和性能指標(biāo)均優(yōu)于同類型機(jī)器，其生產(chǎn)效率更高，損失率更低，經(jīng)濟(jì)效益顯著。
對(duì)于中國(guó)的小規(guī)模農(nóng)田來(lái)說(shuō)，4H-2型花生收獲機(jī)是新型典型的農(nóng)業(yè)產(chǎn)品，更加適合中國(guó)花生生產(chǎn)。這種收獲機(jī)結(jié)構(gòu)簡(jiǎn)單，價(jià)格低廉。它的各項(xiàng)性能指標(biāo)均優(yōu)于中國(guó)花生收獲機(jī)技術(shù)標(biāo)準(zhǔn)。它為客戶帶來(lái)了更多的經(jīng)濟(jì)效益。在應(yīng)用和推廣用于花生生產(chǎn)后，4H-2型花生收獲機(jī)已經(jīng)贏得了社會(huì)廣泛贊譽(yù)。這項(xiàng)專利成果充分表明，4H-2型花生收獲機(jī)的設(shè)計(jì)和原理已經(jīng)達(dá)到了一個(gè)新高度。
參考文獻(xiàn)
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