1. Feed machinery and equipment accessories press roller product introduction
In the granulation process of feed production, the press roller is one of the most important parts. It works in conjunction with the ring mold to shape the powdered feed into a pellet feed with a certain shape, density and hardness by applying pressure to it. The performance of the roller directly affects the quality of feed particles, the production efficiency of the granulator and the overall stability and service life of the equipment.
2. Structural characteristics of the roller
Roll body
The main part of the roller is the roller body, which is generally cylindrical. The outer surface is directly in contact with the feed material and exerts pressure, so the quality and characteristics of the surface have a key influence on the pelletizing effect. The diameter and width of the roller body vary according to the type and production capacity of the granulator, usually between 100-300 mm in diameter and around 50-200 mm in width. In order to ensure good pelleting performance, the surface of the roller body needs to have a high hardness and wear resistance, and should also have a certain roughness to increase the friction between the material and ensure that the material can be effectively sucked into the roller and compacted.
Shaft hole and shaft
A shaft hole is arranged in the center of the roll body for mounting the press roller. The matching accuracy between the shaft hole and the press roller is required to ensure that the press roller can rotate flexibly on the shaft, and to prevent excessive clearance resulting in the press roller shaking or eccentricity. In the pelleting process, the press roller bears the important role of transferring torque and supporting the press roller, and its material and strength need to match the working requirements of the press roller.
Bearings and end caps
Bearings are installed at both ends of the press roller, the type of bearings is usually deep groove ball bearings or cylindrical roller bearings, they can effectively reduce the friction resistance of the press roller in the rotation process, and bear radial and axial loads. The end cover is used to fix the position of the bearing to prevent axial displacement during the working process, and also plays a certain sealing role to protect the bearing from the intrusion of dust, impurities and materials, and extend the service life of the bearing.
3. Material selection of roller
High chromium cast iron
High chromium cast iron is a commonly used roller material, its chromium content is high, generally between 12% and 30%. The presence of chromium makes cast iron have good wear resistance, heat resistance and corrosion resistance. The structure of high chromium cast iron contains a large number of hard carbides, which are evenly distributed in the matrix, which significantly improves the hardness of the surface of the press roll, up to HRC58-65. In the process of friction with feed materials and ring molds, it can effectively resist wear and maintain good pelletizing performance. In addition, the heat resistance of high chromium cast iron makes it able to adapt to the high temperature caused by the extrusion and friction of the material during the granulation process, and it is not easy to deformation or softening. Suitable for all kinds of feed granulators, especially in the processing of high hardness materials or high particle quality requirements of the occasion.
Alloy steel
Alloy steel rollers are also widely used, such as 40Cr, 42CrMo and so on. Alloy steel has high strength, toughness and certain wear resistance. Through the appropriate heat treatment process, such as surface quenching after tempering treatment, the surface hardness of the roller can reach HRC50-55. The advantage of alloy steel roller is that its comprehensive performance is better, it can withstand the pressure and impact load in the pelleting process, and can resist wear to a certain extent. In some small and medium-sized feed pelletizing machines or production lines with strict cost control, alloy steel roller is a more economical and practical choice.
Surfacing alloy
For some rollers whose original material properties are insufficient or whose wear resistance needs to be further improved, surfacing alloys can be used to treat them. Surfacing alloys usually use alloy materials with high hardness and high wear resistance, such as cobalt-based alloys and nickel-based alloys. By surfacing an alloy layer with a thickness of 3-8 mm on the surface of the press roll, the wear resistance of the press roll can be significantly enhanced and its service life can be extended. This method can flexibly select the composition and process of surfacing alloy according to the specific use needs and working conditions, and is suitable for situations where there are high requirements for specific materials or special granulation processes.
4. Manufacturing process of press roller
Cast or forged blank
For high chromium cast iron press rolls, the blank is usually manufactured by casting process. In the casting process, the composition, temperature and pouring process of hot metal need to be strictly controlled to ensure that the castings with uniform structure and no defects are obtained. After casting, it is also necessary to carry out annealing treatment to eliminate casting stress and improve the cutting performance of the material. Alloy steel press rollers can be prepared by forging process, forging can refine the grain of metal materials, improve its strength and toughness. The blank after forging also needs to be annealed or normalized to prepare for subsequent machining.
machining
Machining is the key link of press roll manufacturing, including turning, milling, drilling, grinding and other processes. Firstly, the outer circle, shaft hole and two end faces of the blank are processed to the design size through turning processing, and the coaxial and vertical requirements of each part are ensured. When turning the shaft hole, it is necessary to use high-precision machine tools and tools to ensure that the dimensional accuracy and surface roughness of the shaft hole meet the requirements to ensure a good fit between the press roller and the shaft hole. Milling is then carried out to process the keyways or other connecting structures at both ends of the press roll. For the roller surface, the grinding process can be used to further improve its surface finish and cylindricity, so that it can achieve the ideal working surface quality. In the machining process, the processing accuracy of each process should be strictly controlled, and the appropriate cutting parameters and tools should be used to ensure the overall quality of the press roll.
Heat treatment
Heat treatment plays an important role in improving the performance of the roller. For high chromium cast iron roll, generally need to be quenched and tempered treatment, quenching temperature and time according to the material composition and roll size to determine the tempering treatment is used to eliminate quenching stress, stable structure and hardness. The heat treatment process of alloy steel roller usually includes tempering treatment and surface quenching. The tempering treatment can make the roller obtain good comprehensive mechanical properties, and the surface quenching can improve its surface hardness and wear resistance. In the heat treatment process, it is necessary to precisely control the heating temperature, holding time and cooling speed and other process parameters to prevent the deformation of the press roll, cracking and other defects.
5. Performance characteristics of the roller
High wear resistance
In the pelleting process, the press roller has frequent contact with feed materials and ring molds and produces strong friction, so high wear resistance is its primary performance characteristic. Whether it is high chromium cast iron, alloy steel or surface surfacing alloy material, as well as the corresponding heat treatment and surface treatment process, it is to improve the hardness and wear resistance of the press roll surface. High wear resistance can ensure that the surface wear of the roller is slow during the long working process, maintain stable pelletizing performance, and reduce the particle quality and production efficiency caused by the wear of the roller. For example, in the continuous operation of large feed pelletizing machine, the high wear resistance of the press roller can work continuously for thousands of hours without replacement, greatly improving the utilization rate and production efficiency of the equipment.
Good compressive strength
In the process of pelleting, the press roller needs to apply greater pressure to the powdered feed, so that it is formed into particles through the die holes of the ring die. Therefore, the roller must have good compressive strength and be able to withstand the high pressure in the granulation process without deformation or damage. The high quality material and reasonable structural design enable the roller to effectively transfer the pressure to the material to ensure that the density and hardness of the particles meet the requirements. In the production of high-density feed particles, such as aquatic feed particles, the compressive strength of the press roller is particularly important, which can ensure that the material can be smoothly formed under high pressure, and the press roller itself will not be damaged or failed.
Stable transmission performance
The press roll is connected with the transmission system of pelletizing machine through the press roller shaft, and the stability of its transmission performance directly affects the running stability of pelletizing machine and the consistency of particle quality. The high-precision fit between the roller and the shaft and the good performance of the bearing ensure that the torque can be transmitted stably to the roller, so that it can maintain a uniform speed and smooth during the rotation process. Stable transmission performance helps to avoid problems such as uneven particle size and irregular shape caused by roller speed fluctuations or eccentric rotation, and improve the quality stability of feed products.
Good fit with the ring mold
Roller and ring die are a pair of key parts in pelletizing machine, and the compatibility between them is directly related to the pelletizing effect. Parameters such as the diameter, width, surface roughness and hardness of the roller need to match the corresponding parameters of the ring die. For example, the diameter of the press roll should be in proportion to the inner diameter of the ring die to ensure that a suitable extrusion gap is formed between the two; The surface roughness of the roller should be able to match well with the surface of the die hole of the ring die, so that the material can be smoothly sucked into and extruded. Good adaptation performance can improve the production efficiency of the granulator, reduce energy consumption, and ensure the quality of the produced feed particles, such as the hardness, density, appearance and shape of the particles can meet the standard requirements.
6. FAQ
Q: What is the main material of the roller?
A: The roller is usually made of high-strength steel or alloy steel to ensure that it has sufficient strength and wear resistance. These materials can withstand high loads and long periods of use.
Q: What are the surface treatment processes of the roller?
A: The common surface treatment process of the press roll includes quenching, carburizing and nitriding. These processes can improve the hardness and wear resistance of the surface and extend the service life.
Q: How to ensure the transmission efficiency of the press roller?
A: In order to ensure the transmission efficiency of the press roller, the coordination accuracy between the shaft and the roller should be ensured, the lubrication system should be checked and maintained regularly, and the lubricating oil should be kept clean and appropriate.
Q: What problems may occur during the use of the roller?
A: The press roller may have problems such as wear, fracture, deformation or poor fit during use. These problems are usually caused by overload, inadequate lubrication, or material defects.
Q: How long is the replacement cycle of the press roller?
A: The replacement cycle of the press roller depends on the frequency of use, the working environment and the operation of the equipment. In general, when significant wear, deformation or inability to effectively drive is found, a new roller should be considered.
Q: What are the special requirements of the roller in different application scenarios?
Answer: In different application scenarios, the press roller may have different special requirements. For example, rollers used in high temperature environments need to have high temperature resistance; For use in corrosive environments, corrosion-resistant materials are required.
Q: What are the heat treatment processes of the press roller?
A: The heat treatment process of the press roller includes quenching, tempering and normalizing. These processes can improve the mechanical properties of the material, increase its hardness and wear resistance, and thus extend the service life of the press roll.
Q: Is it important to test the dynamic balance of the roller?
A: Very important. Dynamic balance testing can ensure that the roller remains stable when rotating at high speeds, reducing vibration and noise, and improving the operating efficiency and life of the equipment. Rollers that are not tested for dynamic balance can lead to premature wear and failure of the equipment.
