Hammerhead is an important part of the crusher. The high-quality wear-resistant hammerhead is the foundation to ensure the normal operation of the crusher. The service life of hammerhead depends on the quality and the characteristics of the crushed raw materials, which also determines the crusher’s working efficiency.
Commonly used crusher hammerhead materials in the mining machinery industry mainly include the following types: high manganese steel, medium manganese steel, high chromium cast iron, and low carbon alloy steel. The hammerheads made of these materials have their own characteristics, and also have their own advantages and disadvantages:
High-manganese steel is the traditional material of the hammerhead. It is typical wear-resistant steel that resists impact and wear. It has good toughness and strong work hardening tendency, and shows superior wear resistance under impact conditions. Under greater impact or contact stress, the surface layer will quickly produce work hardening, and its work hardening index is 5-7 times higher than other materials, and the wear resistance is greatly improved.
However, the wear resistance of high manganese steel shows its superiority only under the condition that it is sufficient to form work hardening. In other cases, such as insufficient physical impact force or small contact stress, which cannot make the surface quickly produce work hardening, the wear resistance is very poor.
Medium-manganese steel does not increase the price of the hammerhead, but also achieves the effect of using high-manganese steel hammerheads. The actual service life is increased by more than 50% compared with the construction of high-manganese steel. The biggest advantage of the cast manganese steel hammerhead is that it is magnetic, which can remove iron filings from the ore by magnetic separation, while high manganese steel does not have this advantage.
High chromium cast iron is a kind of wear-resistant material with excellent wear resistance, but it is easy to brittle fracture due to its low toughness. In order to ensure the safe operation of high chromium cast iron hammerheads, composite hammerheads have been developed, that is, cast high chromium cast iron in the head part of high manganese steel hammerhead or low alloy steel hammerhead, or adopt high chromium cast iron to make the working part and adopt carbon steel to make the handle of hammerhead, making the hammerhead head have high hardness and high wear resistance, and the hammerhead handle has high toughness.
Low carbon alloy steel is mainly alloy structural steel containing chromium, molybdenum and other elements, with high hardness and good toughness, and the hammerhead has a long service life. Under the same working conditions, its service life is at least twice as long as that of high manganese steel hammerheads.
However, the manufacturing process is complicated and the process requirements are strict, and the quenching and tempering heat treatment of the hammerhead head is critical. After the quenching and tempering heat treatment, not only the overall tensile strength is required to be above 850MPa, but also considerable plasticity and toughness are required.
The hammerhead is one of the core components of hammer crusher, and its quality is related to the length of the service life. Therefore, the hammerhead is required not only to have high hardness and wear resistance, but also to have high toughness and impact resistance.
In summary, we all hope to find hammerhead materials with high toughness and hardness, but there are few hammerhead materials that can balance toughness and hardness. The two are a contradiction. Therefore, when choosing the hammerhead material, it is necessary to fully understand the working conditions and wear mechanism, and choose the hammerhead material reasonably.
Here are some tips on how to choose between the toughness and hardness of the hammerhead material:
Tip 1: When the hardness of the raw material to be crushed is higher, the hardness requirement of the hammerhead material is also higher, and the larger the size of the raw material is, the higher the toughness requirement is. Therefore, we should choose the hammerhead material according to size and hardness of raw materials to be crushed.
Tip 2: The larger the size of the crusher, the heavier the weight of the hammerhead, the greater the size of the crushed material, and the greater the impact loads on the hammerhead. In this case, when choosing the material of the hammerhead, the toughness of the hammer head should be guaranteed first, and then consider how to improve the hardness of the hammerhead under the premise of ensuring the toughness of the hammerhead.
Tip 3: In addition to the above two points, we should also comprehensively consider the rationality of the process, and consider the cost-effectiveness of the product, as well as the market acceptance, use effect, etc.
After selecting the right hammerhead, the hammerhead should be correctly used and scientifically maintained in production to keep the equipment in good condition and improve the service life of the hammerhead.
Special attention should be paid to the following points in the daily use and maintenance of the hammer crusher:
1) According to the design model of crusher, the feeding size should be appropriately controlled, and the raw material exceeding the design maximum limit size is strictly prohibited from entering the machine.
2) Choose appropriate feeding equipment, such as an apron feeder or vibrating feeder, to ensure uniform and stable feeding, and avoid impact and ineffective operation of the equipment due to uneven feeding.
3) Due to the quality error of the hammerhead during casting, it should be turned over on time according to the current situation during use, so that the hammerhead wears evenly and the rotor runs in balance.
4) When replacing the new hammerheads, it is better to weigh them and divide them into several groups according to the quality. The quality of each group should be equal; otherwise the unbalance of the rotor will easily cause vibration when starting up.
5) When stopping the crusher, check the gap between the hammerhead and the screen bar, and the gap among the screen bars, adjust them if necessary, and replace the screen bar regularly.
6) The hammer frame of the hammer crusher is made of cast steel material and has less contact with materials. However, when metal objects enter the crusher or the liner falls off, the middle hammer disc is easy to damage or bending. In this case, it must be replaced in time. Otherwise, it is easy to clamp the hammerhead and cause vibration.
7) Due to the impact of raw materials between the side hammer plate of the hammer frame and the side plate of the casing, the side hammer plate wears more serious. In order to prolong the service life of the side plate, operators can surfacing welding a wear-resistant layer on the circumference of the side plate and the side close to the side plate.
8) Due to the friction during operation, the shaft diameter at both ends of the main shaft is easy to wear. When installing, add two bushings to the shaft diameter to protect the shaft diameter.
9) Repair and adjust the bearings in time after they are worn out. After the bearing is worn, the bearing bush should be scraped according to the new size, and the thickness of the gasket should be adjusted to maintain a reasonable gap in order to form an effective lubricating oil film.
10) It is necessary to clean up the accumulated material inside the crusher regularly. The accumulated material will severely wear the hammerhead and reduce the service life.
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