Crusher blow bars is one of the key factors affecting the working efficiency of impact crusher. crusher blow bars has different materials and shapes, and also has different fixing methods. This article mainly introduces the relevant information about the blow bar. I hope it can be help everyone.
What is a crusher blow bars?
Crusher blow bars is generally a common wearing part of the impact crusher, and it is the basis for determining the efficiency of the impact crusher. The shape of the crusher blow bars is closely related to the fastening method and the working load. The design of the crusher blow bars should meet the requirements of reliable operation, easy loading and unloading and improvement of the utilization rate of the crusher blow bars.
Crusher blow bars are generally made of high chromium cast iron, high manganese steel and other wear-resistant alloy steels. There are many shapes of crusher blow bars, such as long, T-shaped, and S-shaped, but they are generally long.
Common material of crusher blow bars?
High manganese steel blow bar
High manganese steel blow bar are widely used in crushing equipment such as metallurgy, mining, building materials, railways, electric power and coal. High manganese steel blow bar have good toughness, good manufacturability and low price. Under the action of greater impact or contact stress, the surface layer will rapidly produce work hardening, and the wear resistance will be greatly improved.
However, the high manganese steel crusher blow bar has high requirements on the overall performance of the crusher. If the physical impact force is not enough or the contact stress is small in actual work, the surface cannot be hardened rapidly, so that it cannot exert its due wear resistance.
High chrome alloy blow bar
High chromium alloy blow bar has high hardness and is a high-quality wear-resistant material, which is widely used in crushers. High chromium alloy has high hardness after heat treatment, its matrix is martensite with high hardness, and the structure contains a large number of high hardness carbides, which is widely used as a wear-resistant material for crushers.
Carbide blow bar
Compared with other materials, cemented carbide blow bar has the characteristics of higher hardness, bending strength, impact resistance, thermal fatigue resistance, good toughness and low cost. At the same time, it also solves the problems of cracks, desoldering, chipping and falling blocks that are prone to occur in high manganese materials.
High chromium cast iron blow bar
The high chromium cast iron blow bar can improve the hardness of the entire cross-section through proper alloying and related technological measures. During the wear process, not only the hardness is guaranteed, but also high wear resistance.
Three ways to fix the crusher blow bars?
The crusher blow bars is axially inserted into the corresponding slot hole of the rotor from the side of the rotor. In order to prevent axial movement, the two ends are positioned with pressure plates. Because the fastening bolt is removed, the reliability of the blow bar is improved. The self-locking is fastened by utilizing the centrifugal inertial force generated when the blow bar rotates and the reaction force when impacted and broken.
And the part of the rotor easily subject to wear is made into a replaceable structural form, so it is easy to assemble and disassemble, and easy to manufacture. However, the bolt is exposed on the striking surface and is easily damaged, and the bolt is subject to a large shear force, which will cause a serious accident once sheared.
The blow bar of the impact crusher is inserted into the groove of the rotor from the side, and the two ends are pressed by the pressure plate. However, this fixing method makes the blow bar not firm enough, and the blow bar is easy to loosen during work. High, and alloy materials such as high manganese steel are not easy to process.
Wedges are used to fix the blow bar on the rotor. Under the action of centrifugal force during work, this fixing method can ensure that the faster the rotor speed, the firmer the blow bar is fixed, and the work is reliable, and the replacement is more convenient. This is a better fixing method for the blow bar at present, and it is a relatively common fixing method at present. The wedge is made of cast steel, which has certain toughness and plasticity, high strength and hardness, and good machinability.
Inspection of the fastening condition of the crusher blow bars?
The embedded fastening of the blow bar of the crusher refers to inserting the blow bar into the groove of the rotor from the side, and the two ends need to be positioned with a pressure plate to prevent axial movement, because the fastening bolts are removed, which improves the reliability of the work of the blow bar.
Utilize the centrifugal force generated when the hammer head rotates and the reaction force when it hits and breaks to tighten and self-lock, and the parts of the rotor that are prone to wear are made into a replaceable structure, so it is easy to assemble and disassemble, and simple to manufacture.
The metal utilization rate of this method is low, but the improved embedded fastening method adopts a grooved blow bar, and there are longitudinal grooves on the hammer surface, which greatly reduces the metal consumption rate, and the working surface can also be exchanged for four times, effectively Prolong the service life of the blow bar.
There is also a method of fixing the blow bar wedges of the crusher. This method is mainly to insert the wedges into the corresponding slots between the blow bar and the rotor to tighten them. The wedge fixing method is more reliable, and the loading and unloading is more convenient. Since the relative shift between the blow bar and the rotor is eliminated, the wear of the rotor is reduced. It can greatly reduce the wear degree of the blow bar and the rotor, but the utilization rate of the available metal is low.
At the same time, the way of fixing the blow bar of the crusher with bolts is also relatively common. In this method, the blow bar is fixed on the blow bar seat of the rotor by means of bolts. The blow bar seat has a tenon shape, which can use the tenon to bear the impact force of the blow bar during work, avoid the bolts from being sheared, and improve the reliability of the bolt connection.
The tightening of bolts must be carried out twice, the first time is the initial tightening, the initial tightening is tightened to 60% to 80% of the standard axial force of the bolt, and the torque value of the initial tightening shall not be less than the percentage of the final tightening torque value of 30. The second tightening is the final tightening, and the torsional shear type high-strength bolts should unscrew the torx chuck during the final tightening. In order to make all the bolts in the bolt group evenly stressed, the initial tightening and final tightening should be carried out in a certain order.
The wear problem and solution of the crusher blow bars?
Crusher blow bars wear is the main wear form of the crusher. Generally, the blow bar has a short service life and a large consumption. It needs to reserve a large number of spare parts to maintain normal production, and the production cost is high.
There are generally two reasons for the short service life of the blow bar: one is the improper selection of the blow bar material. Blow bar materials often use high manganese steel, high manganese steel is characterized by good toughness, high strength, good workmanship, and certain hardness. Under the action of large impact or contact stress, the surface layer of high manganese steel will quickly produce severe Work hardening, greatly improving surface hardness and wear resistance. However, in actual use, the impact force or contact stress is often insufficient, and the surface cannot be rapidly hardened, and the wear resistance cannot be fully exerted.
Second, the choice of blow bar structure is not enough. There are many structural forms of the blow bar. There are two kinds of working faces: wide and thick and narrow and thin. The wide and thick have a large amount of effective wear; there are single-head work and double-head work, and there are single-side work and double-side work.
There is only one wear of a single head. There are two wear surfaces for double heads, and four wear surfaces for double heads and double sides. Under the condition of the same material, the effective wear amount is large, and the blow bar with more wear surfaces has longer service wear.
Treatment measures: To improve the service life of the crusher blow bars, we can start from two aspects: choosing the material of the blow bar and optimizing the structure of the blow bar. In order to improve the service life of the blow bar, the blow bar should choose some materials with better wear resistance, such as high chromium cast iron and low carbon alloy steel. High chromium cast iron is a material with excellent wear resistance, and its wear resistance is stronger than that of high manganese steel, but its disadvantage is its low toughness.
Brittle fractures are prone to occur in the case of large impact. In order to improve the strength of the blow bar and reduce the cost, a layer of high chromium cast iron can be surfacing on the high manganese steel bar to achieve the purpose of wear resistance. Low-carbon alloy steel is mainly alloy structural steel containing chromium and molybdenum.
It has high hardness and good toughness. Under the same conditions, its service life is at least twice that of high manganese steel, but the heat treatment process is the key. In terms of the structure selection of the blow bar, if the technological conditions permit, choose the structure of the blow bar with wide and thick working faces, double heads and double sides, which can greatly improve the service life of the blow bar.
How to improve the service life of the crusher blow bars?
The gap between the impact plate and the blow bar of the crusher can be adjusted, which can greatly prolong the service life of the blow bar. The over-iron safety device of the crusher effectively reduces the damage to the parts caused by foreign objects, and also improves the crusher’s safety. service life.
Some emerging crushing technologies can also be used to meet the process requirements of “more crushing and less grinding”. At the same time, the principle of “stone striking iron” can also be used for crushing, which not only improves the crushing ratio, but also has low unit power consumption, which is a very good energy-saving technology.
Removal and installation of crusher blow bars?
Disassembly of the blow bar
First of all, use a special flip device to open the rear upper frame of the crusher to facilitate the subsequent work, turn the rotor by hand, turn the blow bar to be replaced to the position of the inspection door, then fix the rotor, and remove the blow bar. Position the part, then remove the pressing block along the axis, and then push the blow bar out from the inspection door along the axis, or lift it out from the frame. In order to facilitate the disassembly of the blow bar, you can tap the blow bar lightly with a hand hammer.
Blow bar installation
When installing the blow bar, the above process is reversed, and the blow bar is disassembled according to the correct steps, which can save the time of stopping the machine, thereby improving the working efficiency of the crusher and improving the corresponding economic benefits.
This is the whole introduction to the crusher blow bars in this article. I hope everyone has obtained the knowledge they want. If you still have something you want to know, you can also leave a comment below the article, and we will reply to everyone’s comments one by one. At the same time, there are other excellent articles on our website, welcome to continue to browse.