油菜脱粒过程中茎秆碰撞破碎的试验研究

油菜脱粒过程中茎秆过度破碎是导致夹带损失和脱粒功耗升高的主要原因。为明确油菜茎秆被脱粒钉齿碰撞导致破碎的机理，该研究以收获期油菜茎秆为研究对象，在自制的碰撞试验台上进行脱粒钉齿与油菜茎秆的碰撞破碎试验。在进行油菜茎秆与脱粒钉齿撞后轨迹分析的基础上，利用感压胶片对脱粒钉齿与油菜茎秆的碰撞力进行了测量，并以油菜茎秆破碎率为指标，以油菜茎秆长度、喂入次数、滚筒转速、齿型等为因素分别进行了单因素试验和正交试验。结果表明：单个钉齿与油菜茎秆的碰撞过程为高速瞬时多点碰撞，碰撞过程89%为多次碰撞，发生1次碰撞的仅占11%，碰撞次数与碰撞点在钉齿上的位置有关；瞬时多次碰撞过程中碰撞力随碰撞次数呈减小趋势，试验条件下单次碰撞力平均值为13.25 N，小于油菜茎秆径向压缩的屈服极限，单次碰撞的油菜茎秆并不会破碎；单因素试验表明油菜茎秆破碎率与茎秆长度、喂入次数、滚筒转速正相关；刀面、柱面和平面3种钉齿中刀面钉齿对茎秆破碎率影响最大，平面钉齿对茎秆破碎率影响最小，试验条件下将油菜茎秆重复8次喂入碰撞试验台后油菜主茎秆上、中、下各部分破碎率分别为84.4%、91.1%、97.8%，油菜侧枝破碎率为42.2%，主茎秆破碎率远远大于侧枝；正交试验表明在所选参数范围内影响茎秆破碎率大小的顺序依次为茎秆长度、滚筒转速、齿型、喂入次数，且茎秆长度100 mm、滚筒转速500 r/min、喂入次数为2次、齿型为平面钉齿时油菜茎秆破碎率最低。本文对脱粒钉齿与油菜茎秆的碰撞形式及碰撞力进行了研究，确定了影响茎秆破碎的主次因素，可为油菜脱粒装置的优化设计提供依据。

Experimental study on impact crushing of rapeseed stalks during threshing of oilseed rape

Abstract: In the process of rape threshing, excessive breakage of stalk is the main reason for the entrainment loss and the increase of the whole power consumption. Harvest rape stalks as the object, this article studies the Collision and crushing test between threshing nail tooth and rape stem to understand the mechanism of the breakage of rape stems caused by the collision of threshing spike tooth on a self-made collision test-bed. Based on the force analysis and trajectory analysis of the collision between rape stalks and spike tooth, we measured the impact force between them by using prescale film. With the breakage rate of rape stalk as the index and length of rape stalk, feeding times, rotational speed of cylinder and type of spike tooth as factors, the single factor experiment and orthogonal experiment were carried out respectively. The results are as follows: The collision process between single spike tooth and rape stalk is a multiple high-speed instantaneous collision, 89% of the collisions are multiple collisions, only 11% have one collision, and the collision times are related to the position of the impact point on the spike tooth. In the process of instantaneous multiple collisions, the collision force decreases with the number of collisions. Under the test conditions, the single impact force is 13.25 N averagely, which is less than the yield limit of rape stalk radial compression. And the stalk collided only once will not be broken. The breakage rate of stalk is positively related to the stalk length, feeding times and rotational speed of cylinder. Among the three kinds of nail tooth , cutter surface, cylinder and plane, the influence of cutter face nail teeth on the stem breakage rate was the greatest, while the influence of plane nail teeth on the stem breakage rate was the least, Under the experimental conditions, the crushing rate of the upper, middle and lower parts of the main stem was 84.4%, 91.1% and 97.8% respectively after feeding the rape stem into the collision test-bed for 8 times, and the fragmentation rate of the lateral branches of the rape was 42.2%, the broken rate of main stem was much higher than that of lateral branch. The orthogonal test shows that, the effect of rape stalk''s length on breakage rate is the greatest, followed by rotational speed of cylinder and type of spike tooth, the effect of feeding times is smallest within the scope of the selected parameters, and when the stalk length was 100 mm, the roller speed was 500 r/min, the feeding times were 2 times, and the tooth shape was flat nail teeth, the Rape Stalk breakage rate was the lowest. In this paper, The collision form and collision force between the threshing nail tooth and the stem of rapeseed are studied, and the main factors affecting the breakage rate of stalk are found out, which can provide the basis for the optimal design of rape threshing device.