Chapter One Introduction to Rice Husking Cots

　　Since the rubber roller hulling machine replaced the sand plate hulling machine and the iron roller rice milling machine, it became the special equipment for rice hulling in the rice milling industry. With its large output, high hulling rate, low rice breaking rate, and power It is widely used by rice processing plants because of its advantages of low consumption and convenient operation. With the increasing development of the rice milling industry, the rubber roller husker is constantly improving and becoming more and more perfect. For example, the emergence of the husker with a single gear box drive hydraulic tension roller is undoubtedly a new generation product, but no matter how complex its structure and how perfect its performance is, it is always inseparable and its basic principles are the same. , That is, by means of the reverse and unequal speed rotation of the two rubber rollers next to each other, the paddy rice is squeezed, torn, and other effects, so as to achieve the purpose of hulling. Therefore, the hulling rubber roller is an indispensable and vulnerable spare part on the hulling machine.

　　Chapter 2 The basic characteristics and performance of the rice hulling rubber roller

　　The classification, structure and model of rubber rollers:

　　There are currently three types of rice hulling rubber rollers in my country and internationally, which are also called three major series, respectively named: wheel type, sleeve type, and build type.

　　Wheel type: Positioning by the center flange hole, 3 or 4 bolt holes are fixed on the two main shafts of the hulling machine.

　　Sleeve type: fixed on the two main shafts of the hulling machine with the tip grooves in the tapered surfaces at both ends, fixed by the taper and cap.

　　Lag type: Use the inner holes of the brackets at both ends to locate, and fix it on the two main shafts of the rice hulling machine with the jacking screws on the brackets at both ends.

　　The old and new model specification comparison table of the rice hulling rubber roller

　　The outer layer of the rubber roller has two colors: brown and white. At present, there are beige, blue and gray in foreign countries.

　　The hardness of the outer layer of the rubber roller (Tai's A type) is 90o, 95o.

　　The basic performance of the rice hulling rubber roller:

　　The basic performance of the 　　 grain hulling rubber roller (the amount of grain) depends on the physical and mechanical properties of the external rubber compound, which can be introduced as follows:

　　(1) Tensile strength: Strength refers to the ability of a material to resist damage caused by external forces. Strength refers to the ratio of the relay force when the rubber test piece is stretched to break and the cross-sectional area of ​​the initial test piece, in MPa( kg/Cm2). For the rubber roller, this is an important mechanical property. The rubber roller must follow a variety of external forces and perform high-speed and violent mechanical movement during the rice milling process. Therefore, the rubber must be very high. The strength of the rubber roller, otherwise it will reduce the use value of the rubber roller.

　　(2) Elasticity: It is one of the most important properties of rubber materials. It refers to the ability of the rubber to deform under the action of external force and return to its original state after the external force is removed. There are many indicators for measuring elasticity, such as: constant stress elongation, elongation, permanent deformation at break and heat generation. For the hulling rubber roller, moderate elasticity is required. Although high elasticity can improve the shelling ability, reduce the bursting of the waist, and less broken rice, but the elasticity is too high, it is easy to produce large elastic deformation, increase the heat generation, increase the working temperature of the rubber roller, and reduce other mechanical and physical properties of the rubber. . For example, the hardness will decrease and it cannot be used. The elasticity is too low, the hardness is too high, the wear resistance is poor, and it is easy to cause damage.

　　(3) Hardness: Hardness refers to the ability of rubber to resist deformation when it is compressed and invaded by external forces. Generally, Shore A hardness tester is used to measure its value. Generally speaking, the hardness requirements of rubber rollers are relatively strict. Too high will increase the glue consumption of the rubber roller and too low of broken rice will reduce the hulling rate. Grain hulling rubber rollers should be equipped with different hardness values ​​according to different regions, seasons and other conditions of use (such as rice type, temperature, etc.). Generally, the hardness of rubber rollers are 85o, 90o, 95o. The tolerance ranges are within ±3 degrees. It must be pointed out that the above hardness is not a fixed value. Depending on the production season, its value is at standard temperature (23℃±2o) and standard Measured under the sample, and the hardness value of the rubber roller in actual work is different from the rated value of the rubber roller, and it will generally be lowered.

　　(4) Anti-aging performance: The so-called aging refers to the deterioration of the quality of rubber due to the physical and chemical effects of oxygen, odor, heat, and light beams in the air during long-term storage and use of rubber. The physical and mechanical properties of the husked rubber roller are degraded and scrapped. After the aging of the husked rubber rollers, they become hard, brittle, cracked, and moldy. The elastic strength of the rubber material is greatly reduced, which seriously affects the use effect, even though the rubber rollers are in production. Many anti-aging measures have been taken at the time, but it is still very important to do a good job in anti-aging work.

　　(5) Balance: Balance refers to the ability of the rubber roller to maintain a fixed axis of rotation when it rotates. Strictly speaking, it is a dynamic balance. However, because the rubber roller is not a precision mechanical part, and the dynamic balance is not easy to measure, it is actually The concept of static balance is adopted, that is, the symmetry of the quality of each part in the warp direction relative to the working axis, commonly known as "heavy". The balance of the rubber roller has an impact on the hulling rate, the brown rice rate, the glue consumption and the normal operation of the rice hulling machine. Have a major impact.

　　Chapter 3 Inspection Standards for Rice Husking Cots

　　Corporate standards: ministerial standards and foreign standards

　　Corporate standards: general corporate standards are higher than ministerial standards

　　Rubber material physical and mechanical performance requirements:

　　Breaking strength: MPa 19 (190K/cm2) or more

　　Elongation at break:% 200 or more

　　Energy consumption reduction cm3/1.61km <0.5

　　Hardness: (Shore A) 85o 90o 95o

　　The allowable tolerance is ±3o, and the difference between the highest and lowest hardness rates on the same rubber roller is greater than 2o.

　　1. Use styrene butadiene rubber to make rubber rollers

　　Rubber test piece: Tearing strength: MPa 23-25

　　Elongation at break% 290-350

　　Abrasion reduction Cm3/1.61km 0.19-1.05

　　Hardness: (Shao A) 95o-96o

　　2, use nitrile rubber to make brown rubber rollers

　　Nitrile rubber: N230; N220; 41 etc.

　　Rubber test piece: Tearing strength: MPa 24-26

　　Elongation at break% 300-360

　　Abrasion reduction Cm3/1.61km 0.08-0.15

　　Hardness: (Shao A) 95o-97o

　　3. Use Ding Ben rubber to make white rubber rollers

　　Rubber test piece: Tearing strength: MPa 22-24

　　Elongation at break% 280-300×320

　　Abrasion loss Cm3/1.61km 0.15-0.10

　　Hardness: (Shao A) 94o-95o

　　4. Use nitrile rubber and PVC to make white rubber rollers

　　Nitrile rubber: N230; N220; 41 etc.

　　PVC: Suspension method PVC-SG4-6 type

　　Rubber test piece: Tearing strength: MPa 24-25

　　Elongation at break% 300-350

　　Abrasion reduction Cm3/1.61km 0.06-0.1

　　Hardness: (Shao A) 96o-98o

　　Chapter 4 The correct use of rice hulling rubber rollers

　　1. The technological conditions of the rice husk:

　　The shelling process of cereal grains generally goes through three basic steps: squeezing, rubbing and tearing, and peeling. Among them, rubbing and tearing are the key to peeling. The size of rubbing and tearing depends on two important factors: one is the friction, and the friction The size depends on the pressure between the two rollers; the second is the length of the relative action time of the reverse friction force on the grain, and the length of this action time depends on the relative speed of the two rollers, that is, the line speed difference is related . It is not difficult to see that the pressure between the rollers and the line speed difference are important process parameters for rice hulling. The correct selection of it not only directly affects the hulling rate, but also affects the consumption of rubber rollers.

　　2. General principles for selecting process parameters:

　　The amount of rice milled by the rubber roller is actually a comprehensive reflection of the hulling rate and the amount of rubber consumption. The two interact and restrict each other. The so-called optimal process state refers to both a high hulling rate and a Lower glue consumption, this is the general principle for selecting various process parameters.

　　1. The choice of line speed difference: The line speed difference is too large, which can enhance the rubbing and tearing force and increase the peeling rate, but it also increases the abrasion and power consumption of the rubber roller. The line speed difference is too small, the hulling rate is low, the loss is low, the rice hulling is increased, and the total rice milling amount is not high. It can be seen that the line speed difference must take into account the two aspects of hulling rate and glue consumption, and one-sided pursuit of either All indicators are wrong. According to my many years of experience, it is better to choose the line speed difference of 2.4-3 m/s. When the line speed difference is less than two meters, the hulling rate will decrease significantly (the speed of the fast roller of the hulling machine is 1350 rpm, and the speed of the slow roller is 1150 revolutions per second; speed ratio is 1: 1.17), the rubber roller is constantly worn out when the hulling machine is working, and the linear speed difference is constantly shrinking, and the fast roller is even more important. In order to ensure a certain process effect, it must be maintained at a certain level. The line speed is poor. When the diameter of the fast roller is smaller than the diameter of the slow roller, the fast roller is replaced immediately. Generally, the diameter of fast rollers is 2-10mm larger than that of slow rollers. In actual work, the selection basis and factors of the linear speed difference are various, such as the variety of rice, the thickness and tightness of the husk, the moisture content and the climate conditions. Wait.

　　2. Selection of the pressure between the rolls: The pressure between the rolls is also one of the key process parameters for the size of the rubbing and tearing force. The pressure between the rolls is adjusted by the weight of the pressure on the roller hulling machine. In principle, it is easy to light but not heavy, and both sides are balanced. , It can increase the weight of the pressure as the rubber roller gradually wears; for the manual roller hulling machine, the width of the distance between the rollers should be equal to the thickness of the rice grains, generally 0.5 (indica)-0.8 (japonica) mm, should be kept diligent The principle of tightly feeding and parallel feeding.

　　3. Methods to improve the service life of the rice hulling rubber rollers and precautions in use:

　　1. Reasonable selection of rubber rollers: black, brown, and white rollers with a Shore hardness of 90o, 95o should be selected reasonably. According to the specific conditions of the rice varieties, climatic conditions, seasons and other specific conditions in the region, a reasonable combination, preferably fast Choose a roller with higher hardness and a slow roller with a lower hardness. Avoid using a single type of rubber roller.

　　2. Control the working temperature: the actual working hardness of the rubber roller during rice milling is 78 o-82 o Shore. According to the measurement: the working temperature should be below 50℃ (when the working temperature is above 60℃, the hardness of the rubber roller will drop by 4-8 degrees).

　　3. Implement multiple rubber rollers alternately: this method can effectively increase the service life of the rubber rollers and the amount of rice milling. Its advantage is that each rubber roller has a working interval, which is beneficial to eliminate fatigue stress, restore rubber performance, facilitate the use of different diameters to adjust the linear speed difference, and effectively control the working temperature.

　　4. Strengthen the storage of rubber rollers: do a good job of anti-aging. The effective storage period of rubber rollers is stipulated as one year, so as to plan to purchase appropriate storage, and to do a good job of storage. The specific storage requirements are as follows:

　　(1) Avoid direct sunlight and rain and snow erosion, and be no less than 1.5 meters away from the heating device.

　　(2) It is forbidden to contact with substances that affect the quality of rubber, such as acids, alkalis, salts, oils, and organic solvents, and should be kept clean.

　　(3) The temperature of the storage warehouse should be kept between 10o and -30o, and the relative temperature should be between 50o and 80o.

　　(4) It should be rotated vertically, and other materials shall not be placed horizontally or piled up. No blows are allowed to avoid deformation and damage.

　　Four. Abnormal phenomena and causes of rubber rollers during use:

　　1, the rubber roller produces a large and small head;

　　Reasons: 1 The weight of both ends is uneven;

　　2 Improper adjustment of rolling distance;

　　3 Uneven rice flow or deflection of the plate;

　　4 The axes of the two rollers are not parallel.

　　2. The middle of the rubber roller is convex or concave:

　　Reason: 1 Concentration or uneven flow layer;

　　2 The dripping board is uneven;

　　3 The gate is worn or crescent-shaped;

　　4 The size of the rubber roller head, only pay attention to the big head.

　　3. The surface of the rubber roller is bad:

　　Reasons: 1. The net grain contains hard impurities;

　　2 The line speed difference is too large, the rolling distance is too small or the pressure is too heavy;

　　3 The hulling machine shakes severely;

　　4 When the moisture content of the rice is too high or the hulling rate is low, only pay attention to adjusting the roller pitch and not the line speed difference.

　　4. The working temperature of the rubber roller is too high:

　　Reason: 1 Poor ventilation;

　　2 The line speed difference is too large, the pressure between rolls is too large, and the rolling distance is too small;

　　3 The roughness of the rice hull is too high;

　　4 Two rollers are in direct contact

　　5. Vertical and horizontal ripples on the surface of the rubber roller:

　　Reasons: 1. The rice is not flowing smoothly;

　　2 Line speed difference or improper selection of rolling distance;

　　3 The rubber roller is loose;

　　4 Static balance is inaccurate.

　　6. ​​The rubber roller wears out too fast:

　　Reasons: 1 The difference in linear velocity between the two rollers is too large, and the hulling rate is too high;

　　2 The pressure between the rolls is too large and the rolling distance is too tight;

　　3 The rice contains impurities and high water content;

　　4 The working temperature of the rubber roller is too high;

　　5 The hardness of the rubber roller is too high.

　　7. Deformation of rubber roller:

　　Reasons: 1 improper storage, partial aging or melting;

　　2 Inaccurate static balance correction, wrong counterweight position;

　　3 The working temperature of the rubber roller is too high

　　4 When it is difficult to hull the rice, the continuous working time is too long.

　　8. Foaming and peeling of rubber roller:

　　Reasons: 1 The quality of the rubber roller is good

　　2 Rubber roller is aging;

　　3 The direct friction time between the two rollers is too long;

　　9. The rubber roller cores, bursts, and collapses:

　　Reasons: 1 The quality of the rubber roller is not good;

　　2 The storage time is too long.

　　10. Rubber roller edge:

　　Reasons: 1 The length of the rubber roller is wrong;

　　2 The lengths of the two rollers are not aligned when they are installed.