The impact crusher is divided into two types, single rotor and double rotor, depending on the number of rotors. Figure 1 shows the Î¦250Ã—1000 single-rotor impact crusher produced in China (for heavy supply). The structure of the crusher is relatively simple, and is mainly composed of a frame, a transmission mechanism, a rotor, a hammer head and a counterattack plate.
1. The frame of the rack impact crusher consists of two parts, an upper frame and a lower frame, which are bolted to each other. Above the shaft line of the rotor is an upper frame on which side and rear doors for inspection and installation are installed. Below the shaft of the rotor is the lower frame, which is bolted to the foundation and mainly to the quality of the entire machine. All parts of the rack that are in contact with the ore are fitted with replaceable wear liners. A chain curtain is installed at the feed port of the crusher to prevent accidents in which the ore flies out of the machine during the crushing process.
2. Transmission mechanism The impact transmission mechanism of the impact crusher is very simple. The motor directly drives the main shaft and the rotor through the pulley to make high-speed rotation. The main shaft is supported by rolling bearings on the bearing housings on both sides of the frame. The bearings are normally lubricated with dry oil.
3. In terms of working principle of the rotor, the biggest difference between the impact crusher and the hammer crusher is that the hammer crusher is a hinged suspension hammer, and the hammer and rotor of the impact crusher are rigidly connected, using the whole The rotary inertia of the rotor impacts the ore to break it. Therefore, the rotor must have sufficient quality to meet the requirements of broken ore. If the rotor mass is too light, the crushing efficiency will decrease. Of course, it can't be too heavy, otherwise it will be difficult to start the crusher.
The rotor of the impact crusher generally adopts a monolithic cast steel structure. This structure has a large mass and is relatively easy to meet the quality energy required by the crusher. At the same time, it is also more durable and easy to install the hammer. There are also some impact crushers that use a combination of several cast steel or steel discs. The combined rotor is easy to manufacture and easy to balance. Some small impact crushers also use steel-welded hollow rotors. Although they are simple in structure and easy to manufacture, they have poor strength and durability.
4. The back plate back plate made of a high-manganese steel or other wear-resistant material, hanging freely inside the machine. One end is hinged to the two sides of the upper frame by a suspension shaft; the other end is supported by a tie rod bolt on the tapered washer of the upper frame by a spherical washer. The counterattack also serves as a safety device for the crusher. When the machine enters a non-crushed object, the impact force on the counterattack plate increases sharply, forcing the pull rod bolt to compress the spherical washer, so that the pull rod bolt is lifted back and lifted, so that the non-crushed material is discharged, thereby ensuring the safety of the whole machine. In addition, by adjusting the nut above the tie rod bolt, the gap between the hammer head and the counterattack plate can be changed to control the particle size range of the crushed product.
Since the counterattack plate is directly involved in the crushing, its shape and structure have a greater influence on the crushing efficiency. In order to obtain the best crushing effect, it is theoretically required that the material and the surface of the counterattack plate should collide vertically. At present, the counterattack plate of the domestic impact crusher is generally made into a fold line shape and an involute shape. The former has a simple structure and is easy to process, but it cannot meet the requirements of the best crushing effect of the ore; the latter is at various points on the counterattack plate, and the materials are The impact is made in the vertical direction, so that the best crushing effect can be obtained. However, due to the difficulty in processing, an approximate involute counter-attack plate composed of a plurality of arcs is generally used.
The number of counterattacks of the impact crusher is generally two, and the large crusher also has three grades.
5. The hammer head is made of high manganese steel or other wear resistant material, like the counterattack plate, and is fixed on the rotor. The fixing method generally has the following three types.
(1) Screw fixing method. Fix the hammer head with screws. This method is the simplest, but the screw is exposed on the striking surface and is easily damaged. In addition, the screw is easily cut off, causing the hammer to fly out of the rotor and cause a serious accident.
(2) Platen fixing method. That is, the hammer head is inserted into the groove of the rotor from the side, and the two ends are pressed by the pressure plate to prevent the left and right movements. Since the hammer head is made of a wear-resistant material, the processing is difficult, and it is difficult to ensure the precise size of the hammer head, and it is easy to assemble and is loose during work.
(3) Wedge fixing method. The wedge is used to secure the hammer to the rotor. At work, due to the centrifugal force, the hammer, wedge and rotor will become more and more tight, the work is more reliable, and the disassembly and assembly is also very convenient. At present, this method is used to fix the hammer head at home and abroad.
The number of hammers is related to the rotor diameter D. Generally, when D < lm, 3 hammers can be used; when D=1-1.5m, 4~6 hammers can be used; when D=1.5~2m , you can choose 6~10 hammers. In addition, when the ore is hard or broken, the number of hammers can be increased.
The shape of the hammer head is relatively large. At present, more used in China is shown in Figure 2. [next]
According to the rotation direction and arrangement position of the rotor, the double-rotor impact crusher can be divided into two counter-rotating crushers with two rotors rotating in the opposite direction, two rotors rotating in the same direction and two rotors rotating in the same direction and having a certain height difference. 3 types. The following is an example of a Î¦250Ã—1250 twin-rotor impact crusher (Fig. 3) produced in China.
The two rotors of the crusher rotate in the same direction, and the two rotors are arranged in parallel and have a certain height difference. It is equivalent to two single-rotor impact crushers used in series, the first rotor is equivalent to coarse crushing, and the second rotor is It is equivalent to fine crushing. However, there are a number of hammers on the two rotors, and the height and shape of the hammers are different, and the rotational speeds of the two rotors are also different. The first rotor has 4 rows of 8 hammers with a line speed of 38 m/s; the second rotor has 6 rows of 12 hammers with a line speed of approximately 50 m/s.
The two rotors of the crusher are respectively rotated by the two motors through the elastic coupling, the hydraulic coupling and the trapezoidal belt at high speed in the same direction. The first stage rotor crushes the -850mm ore to a displacement of -100mm to the second stage crushing chamber. The second stage rotor continues to crush the ore to -20mm and then discharges from the machine. The crusher has a large crushing ratio, a high output, a uniform product size, and a large power consumption.
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