Main factors affecting the normal operation of the stone removal machine

     When the rice stone-removing machine is working normally, the rising air velocity required to penetrate the bed is equivalent to the suspension velocity of wheat. If the air flow speed is too large, the materials on the trend screen surface are easily blown through, the air flow is unevenly distributed, which destroys the automatic classification of the materials and reduces the separation efficiency. If the air velocity is too small, the wheat is unable to levitate, and it is easy to climb up with the stone, causing the stone to contain wheat. At the same time, the materials are automatically graded poorly, and the wheat species also easily contain stones, which also reduces the separation efficiency.

      1. Inclination angle: the angle between the stone-removing screen surface and the horizontal plane becomes the inclination angle. The size of the inclination has an impact on the output of the rice stone removal machine and the efficiency of stone removal, and the effects on the two are contradictory. When the inclination angle is large, it is powerful to the decline of wheat flow. However, the trend efficiency will be reduced. When the inclination angle is small, the wheat flow rate is low and the yield is small. At the same time, it is easy to carry wheat in the stone, which increases the grain content of the feet. The inclination of the rice stone removal machine is generally 5-9.

      2. Throwing angle: The throwing angle refers to the angle between the vibration direction of the sieve body and the screen surface. The form of the vibration of the sieve body of the rice stone removing machine is a reciprocating linear vibration. The vibration direction is different from the vibrating screen and cannot be changed at will. This is the basic condition for the side-by-side stones close to the screen surface to travel along the screen surface. Therefore, choosing an appropriate throwing angle is conducive to automatic grading of materials and upward movement of side-by-side stones. However, when the throwing angle is too large, the material tends to jump away from the screen surface, but it is not conducive to the upward movement of side by side stones. The throwing angle of the rice stone removal machine is generally 30-35.

      3. Amplitude and vibration frequency: Amplitude refers to the amplitude of the sieve body vibration, and the vibration frequency makes it a working parameter that indicates the speed of the sieve body vibration. When the amplitude is large and the frequency is high, the material moves faster on the screen surface, and the automatic classification function is stronger. Conducive to the improvement of separation efficiency and equipment output. However, the amplitude is too large, the frequency is too high, the working surface vibrates violently, the material is prone to jump, and the automatic classification of the material is destroyed. Therefore, the separation efficiency is reduced. On the contrary, the slow movement of the material on the screen surface and the thickening of the material layer are also not conducive to the automatic classification of the material. Not only affects the separation efficiency, but also affects the output of rice stone removal machine. The amplitude of the rice stone removal machine is generally about 3.5-5mm. The frequency of the rice stone removal machine driven by the vibration motor is generally not adjusted, and the frequency of the eccentric rotation of the rice stone removal machine is positively related to its speed.

Calculation and Research on Critical Speed ​​of Spindle System of Rice Mill

  Rice is a basic food crop, and its production and processing have always been valued by our country. The rice mill, as a processing equipment for rice, plays an important role in improving the utilization rate of grain. In the main shaft system of the rice mill, there are many asymmetric parts in the structure of the shaft, and there are many curved grooves on the roller, which leads to the existence of eccentric mass, which will cause severe vibration when the speed increases, making the rate of rice broken Increased, bearing life reduced.

      In order to solve the problem of broken rice rate, the finite element method was used for static analysis and modal analysis of the vertical rice mill. The researchers obtained some enlightening conclusions. However, in the modal analysis, this article only considers a single spindle, and does not take into account the components on the spindle at the same time. In fact, when the roller, pulley and pick roller are installed on the main shaft, the frequency has changed.

      The above problems belong to the field of rotor dynamics in mechanics. But in rotor dynamics, in order to solve this kind of problem, the structure is often simplified, and then the corresponding formula is derived. These formulas have a directional effect, but for a complex rotor system such as a rice mill, its theory is difficult to use. At this time, the use of numerical calculation methods, such as the finite element method for rotor system dynamic analysis has become an effective way. According to the rotor dynamics theory, when the working speed of the rotor system changes, its critical speed will also change accordingly. Due to the complicated structure of the main shaft system, the finite element method was used to analyze it, and the critical speed of the main shaft of the rice mill under different speeds was investigated, so as to provide a method for its calculation, so as to provide a reference for the calculation of the critical speed of similar rotor systems.

The advantages and disadvantages of the horizontal rice mill

Advantages of horizontal rice mill

1. Smooth operation. The bearing only bears radial force, and the bearing stress and torque of the whole machine produced by the unbalanced force are small. The horizontally installed white rollers do not have high requirements for manufacturing and assembly; the technical requirements of the corresponding structural parts are general;

2. The volume and machine weight per unit output are small. Due to the large axial driving force and the high flow rate of rice grains, under the same material flow rate as the vertical rice mill, the diameter of the white roller and the annular area of ​​the white room are both small, and the volume and weight of the whole machine are small. Lighter, lower manufacturing technology requirements, and lower cost;

3. It is convenient to disassemble and assemble the sand roller in the horizontal direction of the rice mill, saving time and effort;

4. The rate of rice production is high, and the spiral groove makes the density of the rice grain fluid uniform over the entire length of the whitening room, and the tumbling movement is good, and the parts of the rice grain are evenly milled;

5. The two white-rolling rollers are very convenient and reasonable to be combined coaxially or off-axis in one rice mill.

Disadvantages of horizontal rice mills

1. Gravity affects the centrifugal acceleration of rice grains, and makes a difference between the upper and lower parts of the whitening room, which affects the uniformity of the whitening degree;

2. The number of rice knives is small, the material is hard, and some are not easy to adjust. For example, the fixed rice knives in the middle and lower parts need to be stopped and adjusted. Although the steel rice knives are wear-resistant, they are easy to damage the rice grains and increase the rate of broken rice;

3. Bran is easy to accumulate in the upper part of the whitening room;

4. After the spiral groove is worn, manual chiseling is required, and the quality after repair is different from person to person; the sand roller is $ 35 knots. After wear, it cannot be adjusted or partially replaced, and the maintenance cost is high.