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Rotary drilling and drilling construction is an advanced pile-pile construction method developed rapidly in China recently. The construction of rotary drilling rig has many characteristics such as high efficiency, low noise, environmental protection, high quality of perforation and high degree of mechanization, but the construction layers are very different. The specific technical requirements of the construction are different. Therefore, only by selecting different rotary drilling rigs to meet the above requirements, scientifically selecting the rotary drilling rig picks and the reasonable use of the picks can enrich the rotary drilling rig to a certain extent. The construction process expands the construction field of rotary drilling rigs.

The failure analysis of the cutters of the rotary drilling rig is carried out. It is believed that the main failure modes of the cutters of the rotary drilling rig are the wear and the shedding of the cutting head. The main cause of the failure of the cuttings is the insufficient bending strength of the alloy and the wear resistance of the alloy. Poor and fatigue resistance, the analysis believes that by improving the purity of raw materials, changing the composition of the alloy, optimizing the forming sintering process, controlling the grain size of the alloy and heat treatment of the alloy, the performance of the coal cutting teeth is enhanced and the service life is improved. 

1. Rotary drilling rig pick failure form

Rotary drill rigs are subjected to high cyclic compressive stress, shear bending stress, periodic or sudden impact load, thermal stress and wear when cutting hard formations. Although the hardness of the formation is not high, it is often In the case of hard ore such as quartz or coal gangue, the picks fail during use, and the main failure modes are alloy fragmentation, wear and fracture.

2, select the carbide cutting material

The principle of selection The environment in which the rotary drilling rig works is quite special, and the working environment of the picking becomes more special. This will easily cause the picking to fail. The main performance is the loss of the pick, the broken head, and the hard The alloyed carbide head is detached and worn. It can be seen that the material selection of the picks should meet certain strength and hardness requirements, wherein the strength mainly refers to the flexural strength and the tensile strength, and of course the picks need to meet the higher impact toughness. In the research process, relatively high-demand materials are usually selected as the pick-up materials. The relatively widely used materials are medium-carbon rare earth low-alloy bainite wear-resistant cast steels.

3. Rotary drilling rig pick design and manufacture

3. 1 For the design of the cutting head of the rotary drilling rig, the geometry should be designed according to a reasonable design method, not only the design of its geometric shape, but also its size, corresponding set parameters, picks. The arrangement and the corresponding parameters during the cutting are designed to match accordingly. It is necessary to ensure that the cemented carbide picks are evenly stressed during the working process, so that the degree of wear is as equal as possible to ensure the movement process. The degree of stability further improves the efficiency of the work of picking coal and rock, and minimizes the wear and damage of the picks, thus ensuring the reliability of the picks.

3. 2 In the actual operation process, it is necessary to carefully study and analyze the actual situation, and carry out targeted experiments according to the actual mining geological conditions, in order to further determine the hardness coefficient and related data of the coal and rock mass, according to the data obtained from the experiment. With the relevant hardness index, select the different types and models of picks and alloy cutter heads for the actual mining work, so as to ensure the maximum service life of the picks, avoid unnecessary losses, improve the impact resistance while ensuring The mining work went smoothly.

3. 3 In the actual mining process, the selection of the cutting tooth material of the rotary drilling rig has certain requirements. Generally, high-quality alloy structural steel with relatively good forging performance should be used. Under the current economic and technological level of China, the main application is 35CrMnSi. In actual operation engineering, this material has relatively high fatigue limit after quenching and tempering, and its impact resistance is also improved, but there are also Certain defects, mainly with relatively obvious temper brittle defects. Therefore, the choice of 42CrMo material as the material of the tooth body can overcome the above-mentioned defects, and the comprehensive performance after the quenching and tempering is improved, and the temper brittleness is also absent. This material is more suitable as a pick. material.

3. 4 In the manufacturing process, it must be strictly in accordance with the relevant design requirements to ensure that the dimensions between the tooth holder and the pick are matched to each other, so that the carbide picks can be freely and flexibly rotated in the corresponding tooth holders, avoiding cutting The phenomenon of partial grinding of the teeth during the operation can also ensure the sharpness of the teeth, thus ensuring the realization of the self-grinding edge function.

3.5 Using the cemented carbide pick-up alloy head surfacing process, using Beijing Guben wear-resistant welding wire with relatively good wear resistance and plasticity, three layers of wear-resistant layer are welded at the joint of the pick body and the alloy head. . Surfacing high-hardness tantalum carbide, which is dispersed on iron-based martensite and retained austenite to protect the substrate from wear. Tantalum carbide is small in size and is about 10 microns in the weld overlay. It is denser and more uniform than high chromium carbides (40 to 60 microns). In the surfacing layer, since the size of the carbide is greatly reduced and the carbide distribution per unit area is more dense, the impact force on the single carbide is greatly reduced when subjected to an impact load, so the entire surfacing layer is Impact resistance will also be significantly improved.

3.5 Advantages The above design schemes and construction techniques can greatly reduce the defects caused by the picks produced by the original process. The picks produced by the new materials and processes can play a good role in the specific operation process. The effect of this provides a favorable technical guarantee for the smooth progress of coal mining work, and also provides guarantee for the economic development of the state and enterprises. To a large extent, its superiority is irreplaceable.

4, summary

In the process of high-rise building construction, because of the special environment and special requirements of mining work, more stringent requirements are imposed on the rotary drilling rig. The carbide cuttings of the rotary drilling rig may occur or occur during the cutting process. A lot of problems, generally mainly the failure of the pick, or the consumption of the number of picks is relatively large, so that the efficiency of the mining is seriously affected and restricted, so that the economy has a certain loss. Through careful and careful analysis of the reasons for the possible occurrence of the picks, the fundamental solution to the problem is proposed from the material, and corresponding countermeasures are taken in time, and corresponding solutions are proposed from the aspects of design scheme and casting process. Improve the stability and reliability of cemented carbide picks, thereby promoting the efficiency of coal production, improving production efficiency, and ultimately achieving high-performance and high-yield mine construction requirements, and improving the efficiency of rotary drilling rigs.

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about the author:

Hu Jianping, born in 1984, master of engineering, mainly engaged in research and development of wear-resisting surfacing. He is currently a research and development expert of Beijing Guben Technology Co., Ltd., providing professional wear-resisting solutions for many domestic machinery factories, and publishing more than 300 papers. .