1、 Design of sawing anti-blocking mechanism for no-tillage planter and its cutting mechanism Liao Qingxi1,Gao Huanwen2,Shu Caixia1 (1.Engineering and Technology College,Huazhong Agricultural University,Wuhan430070,China； 2.Engineering College,China Agricultural University,Beijing100083,Chi
2、na) Abstract: Based on blocking issues of no-tillage planter for dry-land farming in two-crop-a-year region in North of China and shortcomings of anti-blocking mechanism developed, such as higher rotation speed (above 1500 r/min) and bigger power consumption (width power consumption per unit up to 1
3、6 41.74 kW/m, including traction power), a new sawing anti-blocking mechanism was developed and its cutting mechanism was investigated in this paper. Meanwhile stress distribution of the saw-tooth blade calculated by the ANSYS finity element software showed that the saw-tooth blade would be feasible
4、 to cut corn straws. Experimental results in the soil bin showed that: 1)The sawing anti-blocking mechanism with two cutting modes of sustaining and no-sustaining cut could realize an integrated function of cutting and directly throwing by reverse rotation, namely, it could throw straws directly to
5、the rear of the opener by former angle of saw-tooth and thrower； 2)The cutting rate of straws would increase along with the rising of straw moisture and rotation speed, and higher moisture of straws would be of benefit to improving cutting quality； 3)The cutting rate of straws would decrease along w
6、ith the rising of velocity of vehicle while interval of the moved and fixed blade was determined. And the sawing anti-blocking mechanism had higher cutting quality and lower power consumption without leaky cutting and tearing out with small interval of the moved and fixed blade. Compared with other
7、driving anti-blocking mechanisms, theoretical analysis and experimental results showed that the sawing anti-blocking mechanism had fine cut capability and lower rotation speed (650 r/min) and lower power consumption (power consumption per unit width up to 2.95 kW/m) as well as stronger suitability t
8、o different stubbles mulch. Additionally, a new way was found out to improve anti-blocking performance of no-tillage planter. Key words: no-tillage planter； sawing anti-blocking mechanism； cutting mechanism； cutting rate CLC number: S223.2 Document code: A Article ID:1002-6
9、819(2003)05-0064-07 Received date:2003-06-15 1 Introduction Anti-blocking issue of no-tillage planter had become one of the key factors affecting production efficiency and seeding quality of two-crop-a-year region in North of China. It was because there was a great deal of crop stubbles and crop see
10、ding was started shortly after crop had been harvested, leaving no time for crop stubbles to decay. At present, there are two methods to solve anti-blocking issue of no-tillage: 1) Straws were chopped by the straw chopper before seeding, it would lead to adding working procedure and increase costs o
11、f production as well as delaying seeding time； 2) Stubbles were cleared out by driving chopping mechanism fixed on no-tillage planter, such as Strip Wheat Spinning and Furrow Planter made in Hebei Nonghaha Machinery Ltd Corporation and 2BMDF-Corn Strip Chopper made in China Agricultural University1a
12、nd so on. In practice the driving chopping mechanism had significant effect on anti- blocking, but also bigger vibration and noise as well as lower security because straws were chopped at high rotation speed. It was reported that the blade base linear velocity of several main straw chopping mechanis
13、ms was between 37 56 m/s2, mostly chopping mechanism combined with cutting and striking had higher striking velocity and higher power consumption3, e.g. the blade base linear velocity up to 34 m/s could obtain fine cutting effect for corn straws4, and 24 m/s on rice and wheat straws by supporting po
14、le, respectively5. Even if corn straws were cut by sliding cut with vertical blade, its velocity of cutting one straw, two straws and three straws must be up to 10.3 m/s, 13.6 m/s, 15.8 m/s6, respectively, and had higher power consumption. In a word, because the driving chopping mechanism developed
15、presently had high rotation speed ( above 1500 r/min ) and higher power consumption (width power consumption per unit up to 16 41.74 kW/m, including traction power), to decrease rotation speed and power consumption would be urgent in practice. Based on practical problems, the objective in this paper
16、 is to find a way to solve the shortcoming that it 64 is difficult for common smooth blade to seize straws and it must run at higher rotation speed, decrease power consumption and improve cutting effect as well as anti-blocking performance of no-tillage planter. Additionally some experiments were do
17、ne by selecting saw-tooth as cutting blade of no-tillage planter and cutting mechanism of the sawing anti-blocking mechanism was investigated. 2 Structure and cutting rule of the sawing anti-blocking mechanism 2.1 Structure and characteristics The sawing anti-blocking mechanism was made up of saw-to
18、oth blade, throwing ban device, principal shaft, moved and fixed blade combination, covering shell, opener and working frame as well as transmission system. Sketch of the sawing anti-blocking mechanism is shown in Fig. 1. The main parts included saw-tooth blade, throwing ban device as well as fixed
19、blade combinations. Diameter of saw-tooth with 60 teeth was 350 mm； throwing ban device with max 270 mm turning diameter was fixed on between adjacent saw-teeth； fixed blade combinations consisted of fixed blade with tooth and vertical type blade, and tooth type blade same to saw-tooth, Moreover, th
20、e vertical type blade would be used to obstruct straws without cutting from throwing area and participated in cutting straws. The sawing anti-blocking mechanism was fixed on the soil bin device, its width was 600 mm, the interval of adjacent openers was 200 mm. The sawing anti-blocking mechanism had
21、 many characteristics such as straws would be chopped by saw-tooth blade and fixed blade combinations, and had two cutting modes with susta-ining and no-sustaining cutting, the blade base line velocity of saw-tooth was lower to tossing blade type, namely, the sawing anti-blocking mechanism cou
22、ld change higher speed hewing into lower speed sawing. 2.2 Cutting principle The sawing anti-blocking mechanism was driven to reverse rotation by power. First, straws were cut in no-sustaining mode by saw-tooth blades while saw-tooth blades touched straws, then after straws were completely cut down,
23、 they would be free and be thrown to the rear of opener by throwing ban device and inertial force. Second, straws not being completely cut down would be thrown to former upward and be cut in sustaining mode by fixed blade combinations until any of straws would be cut down, straws having been c
24、ut down were thrown to the rear of opener by throwing ban device and saw-tooth. In turn, time after time, straws would be carried out continuously to cut and throw by the sawing anti-blocking mechanism. The lowest point of the saw-tooth blades kept 15 30 mm interval from the soil. In terms of spread
25、ing status of straws in field existed perpendicularity or certain angle with marching direction, saw principal in landscape orientation had been determined for the sawing anti-blocking mechanism in order to decrease repeated cutting, leaky cutting and tearing out. Working procedures of the sawing an
26、ti-blocking mechanism were as follows: 1) no-sustaining cut phase: static straws relative to ground were cut firstly atNpoint by saw-tooth blades, then, straws would be cut down completely or embedded in saw-tooth. Straws being cut down completely would be free and 65 Liao Qingxi et al: Design
27、 of anti-blocking mechanism for no-tillage planter dropped into adjacent saw-tooth； 2) dragging and delivering phase: after straws dropped into adjacent saw-tooth, they would be thrown to former upward by the throwing ban device, moreover, straws embedded in the saw-tooth would be thrown to former u
28、pward by the saw-tooth at higher speed rotation； 3) sustaining cut phase: straws not being cut down completely in no-sustaining cut phase would be cut in sustaining mode by fixed blade combinations atK point until any of straws would be cut down completely； 4)throwing phase: straws being cut down were thrown directly to the rear of opener by tooth former slanting angle
