【作者】 张晋国；

【导师】 高焕文；

【作者基本信息】 中国农业大学 ， 农业机械化工程， 2001， 博士

【摘要】 针对我国北方旱农地区粮食产量低而不稳、土壤侵蚀日趋严重、机械化水平不高等普遍性问题，目前正逐步推行保土保墒的保护性耕作方法。保护性耕作的主要机具是免耕播种机，而防堵装置是影响免耕播种机工作性能的一个关键部件。本文研制出一种新型的带状粉碎防堵装置，并设计出能在大覆盖量下作业的新型玉米免耕播种机。在以下几个方面进行了较为深入的研究： （1）在对国内外免耕播种机防堵装置研究的基础上，针对华北一年两熟地区麦收后地表覆盖量大的特点，通过对驱动式和从动式防堵装置的对比实验，设计出一种具有高效防堵能力的带状粉碎防堵装置，该装置由组合刀片、开沟器、定刀片、罩壳和导草扳组成。结构新颖，具有创新性。 （2）研制出新一代玉米免耕播种机，配以新型防堵机构，防堵性能优越，连续三年分别对三代样机进行的田间试验表明，可在地表整秆覆盖量10t/ha的条件下连续作业而不堵塞，该播种机的防堵性能好。国内外尚未见同类机型。 （3）为了研究带状粉碎防堵装置对麦秸的切碎效果，在特制的实验台上，应用了虚拟仪器测试技术对不同处理的麦秆进行了切断试验，得到了在不同切割速度下对不同长度、不同含水率的麦秆、麦秆的不同切割部位以及有定刀和无定刀情况下的切断率，为麦秸粉碎装置的设计提供了依据。试验结果表明，对于干的长秸秆，刀片切割速度达到15m/s时，切断率达100％；对于干的短秸秆，刀片切割速度需达到20m/m/s以上；要切断湿秸秆需要有40m/s以上的切割线速度；加定刀与不加定刀对于切断麦秸这类软质秸秆是非常重要的，其切断速度差别很大；另外，麦秸不同部位所需要的切断速度也是不一样的，根部较之顶部和中部更难切断。 （4）通过试验分析及理论计算，确定了带状粉碎防堵装置中粉碎刀轴的合适转速及刀片的回转半径。在带状粉碎免耕播种机工作状态下，对成堆麦秸的切断试验结果显示，切断干秸秆时刀轴转速需在1230r/min以上。理论计算结果显示刀轴临界转速为9683r/min。考虑到实际作业效果，又考虑到播种机重心高低对稳定性和振动大小的影响，最终选取刀片旋转半径为27cm，刀轴转速为1800r/min。 （5）在带状粉碎免耕播种机上安装了可调式镇压装置，为了确定不同土壤含水率下的最佳镇压力，对镇压力与出苗率的关系进行了田间试验。试验结果表明，不同的土壤含水率需要不同的镇压力。本机所采用的双斜式镇压装置，当土壤含水率在11-14％时，其最佳镇压力在30-35kg之间。 （6）带状粉碎免耕播种机利用粉碎刀片在开沟器正前方高速旋转强制切草开道，因而在工作中秸秆对粉碎刀轴产生了交变冲击力，机组在作业中发生振动。为了减轻机具的振动，专门对播种机的振动进行了田间测试，探讨了减振措施。采用中央传动，对刀轴进行严格的动平衡，尽量使万向联轴节在工作时处于水平对正位置，提高制造质量，都可使振动减轻。更多还原

【Abstract】 Conservation tillage method is being adopted and extended gradually at the present time in northern arid and semi-arid regions of China as a effective method to solve those problems in crop production, like poor grain yield, limited utilization ratio of precipitation, serious soil erosion and low mechanization level. However, one of the most important limitations to conservation tillage is qualified no-tillage planter, and the anti-blocking mechanism is a key component affecting the performance of the planter. In this thesis, a new strip chopping anti-blocking mechanism and a new no-till planter operating well in heavy straw mulching condition are developed from the following aspects:(1)In order to solve the problem that the no-till planters can not work well when the mulched straw is long and thick, especially in the double cropping area of Huabei Plain where the winter wheat gives a high yield, a new strip chopping anti-blocking mechanism was developed. It consists of a group of rotary blades, a narrow tine opener, a shear bar, a hood and a deflector. The testing results of straw cutting and field experiment show that this mechanism has excellent anti-blocking capability.(2)A new no-till planter equipped with the strip chopping anti-blocking mechanism was developed. Compared with other no-till planters, it possesses higher anti-blocking capability and suits the need of seeding in Huabei plain where the winter wheat-summer corn continuous double cropping system gives much straw and short planting season. It still works well when the mulched straw is more then lOt/ha.(3)An experiment was conducted on a self-made testing equipment to investigate the chopping properties of wheat straw under different conditions. On the basis of testing results, main cutting curves of wheat straw were given under different cutting speeds of rotary blade, with different straw lengths, different moisture contents, different cutting position, different thick of knife edge, with and without shear bar. The curves showed that the moisture contents of straw and the shear bar are the main factors impacting the cutting ratio besides cutting speed. The speed of 40mm/s is necessary to cut off wet straw.(4)The testing results indicate that the rotary speed of the blade axle need to be more then1230 rpm (rotary radius of the blade is 25cm) to cut off straw (with moisture content less then 20%).If the straw is wet, higher speed is required. Through theoretical calculation, the critical rotary speedof the axle is 9683rpm. The reasonable blade axle parameters were chosen. The rotary radius is27cm and the rotary speed of the blade axle is 1800rpm.(5)The effect of pressure of twin inclined presswheels on emergence rate under different soil moisture have been compared in field. The experimental results show that the pressure should be 3035kg when the soil moisture is between 11-14%.(6)Through vibration frequency spectrum analysis of no-till planter in field, its vibration characteristics were found out. The main factors causing vibration and the proposed approaches for improving the dynamic characteristics of the strip chopping no-till planter have been discussed.更多还原