The selective crushing ability of the impact crusher on the material during the impact makes it have more cubic crushing product content than other types of crushers, as shown in Table 1, and at the same time has the characteristics of large crushing ratio. Simplified the crushing process, so it has been developed rapidly in the crushing industry, and is widely used in various related industries.

1. Impact crusher The so-called impact crushing refers to the object being hit by the force in a free state and selectively crushing and crushing along its natural cracks, bedding surface, joint surface and other weak parts (as shown in Figure 3). It is different from the impact force of the object in the constrained state in the hammer crushing. As shown in Figure 4, it is also different from other shearing, economical pressure, grinding and crushing, so the energy consumption in the crushing process is the lowest, and because of its The ability of selective crushing plays a role in separating useful minerals from monomers and obtaining more cubic products.

The impact crusher that applies the impact principle uses a high-speed hammer to impact the material in the crushing cavity at high speed, so that the material is impacted and crushed, and the impacted material is rushed to the impact board at a high speed. After the impact is broken again, the above-mentioned crushing process is repeated by rebounding from the counterattack plate to the striking area of the hammer head. At the same time, the materials still collide and impact between the hammer head and the counterattack plate. When the particle size of the crushed material is smaller than the gap between the hammer head and the impact plate, it will be discharged from the lower part of the machine to be the crushed product.

The crushing energy of materials of different particle sizes is different. The smaller the material is due to the gradual reduction of internal defects, the greater the energy required for crushing. According to the relationship formula between energy and linear velocity: A = mra.

With the improvement of mining capacity, the size of the material block after mining has been increasing, and the single-rotor impact crusher has limited the increase of the feed size due to its rational structure and other reasons, so the double-rotor impact crusher has been developed. In order to improve the role of the second rotor, a dual-rotor impact crusher with a height difference setting was developed. According to the relationship between hammer wear and energy consumption and the linear speed of the rotor, the first one to coarsely crush the material at a lower speed , And the second rotor performs medium and fine crushing of materials at a higher speed, which improves the crushing ratio.

Vertical impact crusher is the representative of impact crusher used in finely crushing materials. We know that the wear of the hammer head increases nonlinearly with the increase in the linear speed of the hammer head, and the linear speed of the hammer head is very high when it is finely crushed, and relatively light materials cannot enter the effective striking area of the high-speed rotary hammer ( Just within the range of the highest linear velocity), resulting in a decrease in the crushing effect and increased wear of the hammer. The vertical impact crusher adopts the center feeding method, the initial speed of the fed material is close to zero, and it is gradually accelerated and then projected out of the rotor for impact crushing, which improves the impact crushing effect and reduces the wear of vulnerable parts. . This type of crusher has evolved into two categories: mechanical and self-lining

2. Impact crusher

As mentioned above, the impact crusher has uneven discharge in actual use, and it is easy to "run big". The impact hammer crusher can solve these problems.

The material is fed into the machine from the feed port, enters the hammer working area, and is broken by the impact of the high-speed rotary hammer. At the same time, the material hits the impact board at high speed and is further broken, and bounces back from the impact board to the hammer. In the head working area, continue to repeat the above-mentioned crushing process, and finally enter the hammering area (the working area between the hammer head and the grate bar), and the grate bar is further subjected to the hammering and grinding action of the hammer. Practice has proved that the material is not fully crushed in one cycle of the rotor, but must be fully crushed after multiple cycles. Large pieces of material may not be sufficiently broken during the impact process. It can be broken by the rolling action between the impact plate and the hammer plate. This effect has been verified by actual experiments (without grate bars, the largest product The particle size does not exceed the gap between the hammer plate and the impact plate).

Third, the structure of the impact hammer crusher

The impact hammer crusher is mainly composed of four parts: body, rotor, grate bar body and transmission device. Here is a brief description of these four major parts

3.1 Body

Its main function is to support the rotor and grate bar body to realize the crushing of materials and to ensure that there is a large enough crushing cavity to fully crush the materials. In addition, in order to prevent the material from abrading the inner wall of the machine body, liners are laid on the inner wall of the machine body that is easy to wear. The counterattack plate should be able to be opened to the proper position (the opening and closing of the counterattack plate for small-size machines is completed by a crane, and the large-size machine is completed by the hydraulic system) to facilitate the replacement of the counterattack lining and other linings. The hammer head can be replaced after opening the access cover. In addition, the grate bar body can be removed to replace the grate bar by opening the access door. Open the observation door to check the size of the gap between the hammer head and the grate bar and the wear of the hammer head.