First, should be based on the nature of the material and the way to force the crushing equipment to find the type of equipment before the selection of crushing equipment, the crushing force should be clearly defined, according to the nature of the particles, particle size and crush the product requirements, to take the appropriate force, and then Seek for smashing equipment types.
1. Crushing and impacting are adopted for hard materials with large or medium granularity, and teeth with different shapes are included in the crushing tools; for example, jaw crushers, tooth roller crushers, etc.
2, the smaller size of the hard material using crushing, impact, grinding, grinding tool surface without teeth, is smooth; such as the roll crusher.
3, powder or mud-like materials using grinding, impact, crushed; such as ball mill.
4. Abrasive weak materials use impact, impact, and grinding, and the grinding tools have sharp teeth.
5. The abrasive material is mainly crushed and the surface of the crushing tool is smooth.
6, tough material using shear or fast blow; such as hammer mill.
7. The multi-component materials are crushed under the action of impact and can also be combined with various force fields.
Second, the requirements of the material of the mill work pieces Dry crushing will rely on the role of high-speed rotating rotor, the particles between the rotor and the fixed stator is crushed by the shear force, or frequent grinding between the rotating parts and the fixed parts, this working principle It is often due to the fact that parts that are in direct contact with the material are heavily worn out, so that insoluble impurities and metal particles are easily contaminated during the crushing process.
Some special materials should avoid the requirement of corrosion resistance when they come in direct contact with the material. Generally, austenite stainless steel is used for this material, while the surface hardness of austenitic stainless steel is relatively low. If austenitic stainless steel is used as the material for the grinding machine, metal particles can easily be produced. However, an important way to reduce the wear particles is to increase the hardness of the grinding machine material. The lower the carbon content in the material, the lower the hardness, and the higher-carbon material, which can easily rust. Therefore, the choice of materials in the crushing equipment should pay attention to handling the contradiction between corrosion resistance and hardness.
To handle the above-mentioned contradictions, it is necessary to analyze the primary and secondary aspects of the conflict, to crush the wear-resisting parts of the machine, and to ensure corrosion resistance under the premise of ensuring wear-resistance. For dry crushing equipment, dry materials generally have almost no precipitation of chloride ions, that is, the probability of intercrystalline corrosion in the material is extremely low, that is, the material of the selected crusher parts must also have similar hardness. 316L ultra low carbon stainless steel. Therefore, the author proposes that the material of the grinding machine can be selected from three aspects:
1. High-alloy nickel-chromium steel.
2. Austenitic stainless steel is treated specially. If it is similar to medical surgical equipment, it is hardened on stainless steel. It is reported that there are already examples of successful application of pharmaceutical machinery manufacturers in China.
3, hard ceramics.
Third, other principles of selection should be considered 1, the bearing and the seal at the rotor, in addition to selecting high-precision bearings, bearings should be multiple sealed. While ensuring that the lubricant in the bearing is not leaked, it is also necessary to ensure that the material powder does not infiltrate into the bearing (that is, no residual dust). This is necessary to prevent cross-contamination.
2. In the dust removal process, a large amount of dust will be released from the powder outlet. Therefore, most of the crushing equipment (especially the grading and combination equipment) have dust removal devices. When selecting the dust removal, the dust removal material should be required. The dust removal material should be determined according to the product type and the degree of safety.
3, the cleanability, in addition to the part of the direct contact with the material without cleaning blind, pay attention to the following points:
(1) For manual cleaning equipment, the part that is in direct contact with the material should be completely disassembled.
(2) For equipment with CIP or WIP, bearing cleaning should be considered.
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