| The hull of rapeseed contains some adverse substance, such as phytic acid, tannin, pigment, sinapine and so on. The traditional method of making oil from rapeseed does not remove the hull of rapeseed, which not only decreases the quality of oil, enhances the color of semi-finished oil ,results in difficulties in refining,but also decreases the quality of rapeseed cakes so that affect its further development and utilization. Therefore, new techniques of hulling and oil manufacture have been concerned, and the equipment development of hull broken and separation technology becomes the key.Basing on the study of the basic physical and mechanical properties of rapeseed, theories of rapeseed hull broken was analyzed.Design and trial-manufacture of rapeseed hull-broken machine were carried out, and hull-broken machine performance experiments was made. It was analyzed that the rate of hull broken and the rate of powder were influenced by rapeseed moisture content, rotating speed and other factors. According to the material composition and property of hull broken rapeseed, the separation principle of hull broken rapeseed and the main structural parameters were analyzed; a kind of hull broken rapeseed separator was designed. Analyzed the factors that affect the performance of separating machines in the method of quadratic orthogonal rotary experiment. The relationship between factors-such as feeding volume, wind speed of front wind tunnel as well as wind speed of behind wind tunnel and the performance index- the rate of hull including kernel and the rate of kernel including hull-were concluded.Conclusions are as follows:(1) Volume shape coefficients of rapeseed for cabbage type,leaf mustard type and wild cabbage type were 0.493,0.468 and 0.513. It respectively close to the spherical volume shape coefficient 0.5238,the granular diameter of rapeseed for cabbage type, leaf mustard type and wild cabbage type obeys to the normal distribution: X~ (1.49,0.14832), X~ (1.25,0.14832) and X~ (1.589,0.24172).(2) The relationship between extrusion force and deformation for single grain rapeseed is an obvious double-peak feature in the compression process, and the first peak has the characteristics of brittle materials. As increase of rapeseed granular diameter, the force value of the two yield point and rupture point was increased .With the increase in moisture content of rapeseed, the force of yield point was decreased, the deformation value of the first yield point was decreased; the deformation value of the second yield point was increased. Along with increase of deformation loading velocity, distortion shearing force and shearing strength were increased.(3) With the increase of rapeseed granular diameter, the shearing force is increased and shearing strength is decreased. With the increase in moisture content, both of shearing force and shearing strength are decreased. With the increase in shear velocity, shearing force and shearing strength are increased.(4) The method of rapeseed hull broken by the twice striking can achieve to break the rapeseed hull. The rate of hull broken is more than 75%, and the rate of powder is less than 5%.(5) The rapeseed grain's kinematics and dynamics equations in acceleration of centrifugal throwing dish have been given. It was proposed that the necessary power for rapeseed breakage is the power of elastic deformation and plastic deformation. The computational equation of the power for rapeseed hull broken was obtained.(6)With the increase in the moisture content of rapeseed, the rate of hull broken and rate of powder decreases .With the increase in feeding volume of hull broken machine for rapeseed, the rate of hull broken and rate of powder decreases also.(7) With the increase of centrifugal throwing dish speed, the rate of hull broken and rate of power were increased. Meanwhile, the difficulty in separation kernel and hull also was increased. (8) Assembling re-threshing boards under the centrifugal throwing dish can improve the performance of hull-broken machine, but the number of the board should not be more than two. The location and height of the best values of re-threshing boards are: 15cm, 5cm.(9) Based on the principle which combines the air current, vibration and screening, the separator of hull broken rapeseed was designed. Hull broken rapeseed can be effectively separated by using different mesh in anterior and posterior of sieve.(10)Regression equations that feeding volume,wind speed of front wind tunnel and that of behind wind tunnel influence performance index of separator were given. The sequences of factors, influencing the rate of hull including kernel, are wind speed of front wind tunnel, wind speed of behind wind tunnel and feeding volume. The sequences of factors, influencing the rate of kernel including hull, are wind speed of front wind tunnel, feeding volume and wind speed of behind wind tunnel. (11) The best combination of operating parameters for separator of hull broken rapeseed are as follows: feeding volume: 650～750kg/h, wind speed of front wind tunnel: 1.5m/s, wind speed of behind wind tunnel: 5.14m/s.(12) It have correlation that the rate of hull including kernel and the rate of kernel including hull were influenced by feeding volume, wind speed of front wind tunnel and wind speed of behind wind tunnel. Particularly, wind speed of behind wind tunnel and the other two factors have obvious correlation.The innovations of this thesis are as follows:(1) Based on the twice striking method, the principle of rapeseed hull broken was proposed;(2) The separation principle of combination of air, vibration, and screening for rapeseed of hull broken was proposed. Hull broken rapeseed can be effectively separated by using different mesh in anterior and posterior of sieve;(3) The computational method of power for the rapeseed hull broken was proposed;(4) The regression model which the rate of hull in including kernel,the rate of kernel including hull were influenced by feeding volume, wind speed of front wind tunnel as well as wind speed of behind wind tunnel was established. |
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