Rotary drill cutting teeth

Rotary digging into construction is quickly developed recently in our country's advanced pile driving construction methods, construction of the rotating drill with high efficiency, low noise, environmental protection, pore forming many characteristics, high quality, high mechanization degree, but the construction of the formation of differ in thousands ways, the specific technical requirements and construction are different, so only by selecting different rotating drill cutter teeth to meet the requirements of the above, scientifically choose the rotating drill cut teeth, reasonable use of cutting tooth, to a certain extent, can enrich the construction technology of rotating drill, expanding the area of the construction of the rotating drill.



Has carried on the failure analysis of rotating drill cut teeth, think that the main failure form of cutter tooth is a rotating drill wear and cutting tooth head loss, cause tooth cutting strata failure alloy was the main cause of the bending strength is not enough and low alloy wear resistance and fatigue resistance is poorer, analysis may be changed by improving the raw material purity, alloy composition, optimization of molding, sintering process, control of jin jing granularity and the alloy heat treatment process to improve to enhance the performance of the coal cutter tooth, improve the service life.



1. Failure mode of cutting teeth of rotary drilling machine



When rotating drill cutter tooth cutting hard strata under high cyclic compressive stress, shear bending stress, cyclical or sudden shock load and thermal stress, the wear effect, although the formation of hardness is not high, but often quartz, coal gangue harder minerals, such as cutting gear failure in use process, the main failure modes are alloy fracture, wear and fracture.



2. Select cemented carbide cutting material



The principle of selection is that the working environment of rotary drilling machine is relatively special, so the working environment of the cutting teeth will become more special. In this way, the cutting teeth will be prone to failure, which is mainly manifested as the loss of the cutting teeth, the fracture of the cutting head, the falling off and wear of cemented carbide cutting head, etc. Thus it can be seen that the material selection of the tooth to meet a certain strength and hardness requirements, strength mainly refers to the bending strength and tensile strength, of course, the tooth also needs to meet a higher impact toughness. In the research process, the materials with relatively high requirements are usually selected as the cutting materials, among which the materials with relatively wide application are the medium carbon content of rare earth low alloy bainite abrasion resistant cast steel.



3. Design and manufacture of cutting teeth of rotary drilling machine



3. 1 for the design of the cutting head rotating drill, its geometry according to certain reasonable design methods to design, not only to the geometric shape and reasonable design, for its size, a collection of corresponding parameters more, cutter tooth arrangement, and corresponding cutting parameters to design the corresponding matching, to ensure that in the process of use, can make the hard alloy cutter tooth uniform stress in the work, make the degree of wear is the same as far as possible, guarantee the smooth degree of motion process, further improve the efficiency of the cutter tooth cutting coal and rock work, as far as possible to reduce wear and damage of may, to ensure reliability was improved.



3. 2 in the process of actual operation, need careful research and analysis on the actual situation, according to the practical geological conditions of mining targeted experiment, in order to further determine the coal and rock hardness coefficient and the related data, according to the data obtained from experiments, and the related hardness index, choose a different brand and model of cutter tooth and alloy tool bit for the mining work, so as to ensure the service life of cutter tooth reached maximum, avoid unnecessary losses, improve the impact resistance at the same time also can ensure the smooth progress of mining work.



3. 3 in the actual mining process, there are certain requirements for the selection of the material of the cutting teeth of rotary drilling machine. Generally, high quality alloy structural steel with relatively good forging performance should be adopted. Under the current economic and technological conditions in China, 35CrMnSi is widely used. In practical operation engineering, this material has relatively high fatigue limit and improved impact resistance ability after tempering, but it also has certain defects, mainly due to the obvious brittleness defect of tempering. Therefore, choosing 42CrMo material as the tooth material can overcome the defects mentioned above. After quenching and tempering, the comprehensive performance is improved to a certain extent, and the temper brittleness is also eliminated. This material is more suitable to be used as the cutting material.



3. 4 in the manufacturing process, in strict accordance with the relevant design requirements for production, to ensure the tooth size together with cutting teeth, guarantee the carbide cutting teeth on the corresponding free flexible rotation, avoid cutting teeth eccentric wear phenomenon occurred during the process of operation, also can ensure the sharp blade, so as to ensure the realization of the function of autogenous grinding blade.



3.5 The hardalloy cutter head surfacing process is used. Beijing solid wear resistance wire with relatively good wear resistance and plasticity is selected. Three wear resistance layers are surfacing between the cutter body and the weld of the alloy head. The hardfaced niobium carbide is distributed on the fe-martensite and residual austenite to protect the substrate from wear. Niobium carbide has a small size, about 10 microns in the surfacing layer, and its distribution is denser and more uniform than that of high chromium carbide (40 ~ 60 microns). In the surfacing layer, because the size of carbide is greatly reduced and the distribution of carbide per unit area is more dense, the impact force of single carbide will be greatly reduced when subjected to impact load, so the impact resistance of the whole surfacing layer will also be significantly improved.



3.5 superiority than using the design scheme and construction technology, can largely reduce the production of the original section of tooth defect, use the production of new materials, new cutting tooth in the concrete operation process can have very good effect, the progress of the coal mining provides a favorable technical support, also to the state and the economic development of the enterprise provides the security, to a great extent, its superiority is irreplaceable.



4, summarize



In high-rise building construction process, because of the special environment of the mining and special requirements are put forward to the rotating drill more strict requirements, the rotating drill carbide cutter tooth in the process of cutting may occur or encounter many problems, mainly pick failure commonly, or pick a relatively large amount of consumption, makes the formation of mining efficiency is affected by the serious and constraints, so as to make the produce certain economic losses. By means of cutting teeth of careful earnest analysis, the cause of these conditions from the fundamental solution to the questions on material, adopt corresponding measures in time, from the aspects of design, such as casting process put forward the corresponding solution, improve the stability and reliability of cemented carbide cutter tooth, thus promoting effect on the benefit of coal production, improve the efficiency of production, ultimately meet the requirements of high efficiency and high yield of mine construction, enhances the working efficiency of the rotating drill.