Research On Antiwear Performance Of Impregnated Diamond Bionic Structure

In recent years, the national economy is developing rapidly, and the demand for minerals and resources is more and more, so the exploring work is increasing fast. However, the difficulty for exploring minerals and resources is bigger and bigger, and the strata for drilling are complex increasingly. The materials and funds are consumed largely for exploring minerals and resources, therefore, the drilling technique is very important apparently. When the drilling well is deep especially, 70% of the time is used to hoist and put in the drilling pipes, so the drilling bit as a tool of drilling rocks has an important impact on the construction progress. In a word, it is necessary to develop a new type of drilling bit, which has not only high drilling efficiency but long life as well, and this is a main way to reduce the drilling cost.At present, many researchers are trying to develop the new type of drilling bit, such as changing the structure design, developing new cutter, adding the work layer height and so on. Much progress has been made, and many new theories, new techniques and new products are appearing in the gross. However, the cost of drilling bit is adding more quickly than the selling price of drilling bit in our country, and the profit is very little as a result of excess capacity, so the fund for developing the new type of drilling bit is lack. On the contrary, the foreign companies are increasing the investment to improve the drilling efficiency and life of drilling bit, as a result, the gas is being widened rapidly between the domestic and the foreign.Bionics is considered as the inexhaustible source of power from the original scientific and technological innovation, and it is an important means of developing high-tech. All of life-forms have own particular coat for fitting their living environment, and this phenomenon is very ordinary. For example, many soil animals have non-smooth surface, and researchers have made a lot of efforts to study the non-smooth surface, this is named as so-called bionic non-smooth theory, which is providing much new idea for solving many problems, and the non-smooth surface was proved to have favorable characteristics, such as self-cleaning, desorption, drag reduction, anti-wear and so on. Bionic coupling theory, which evolved from the non-smooth bionic theory, includes not only the research of the shape of non-smooth surface and inner structure of organisms and material. This theory has now applied to many fields.Based on the bionic coupling theory, the bionic structure bit was developed, and it worked well in field experiment. For example, in a gold mine area, the rock hardness varies from 6 to 8, and the stratum is integrated, and the rock is defined as metamorphic rocks, which has a large content of quartz. The experimental result indicates that the drilling efficiency and life of bionic coupling bit improved obviously contrast to the ordinary impregnated diamond bit. The drilling experiment of bionic coupling oil-bit in northern Sichuan shows that the life of bionic structure bit increased by 66% and 388%, and its drilling efficiency increased by 19.7% and decreased by 15.7% contrast to the first two roller bit. In a word, the experiment had reached the desired effect.In the progressing of manufacturing bionic coupling bit, the diameter of bionic unit was selected according to some correlative papers. In addition, the arrangement of bionic unit was random. Up to now, the question is not researched in detail. This paper discussed the diameter and arrangement of bionic unit, which have an important impact on drilling efficiency and life of bionic structure bit. The purpose is to find optimal diameter and arrangement of bionic unit for further improving the anti-wear characteristic of bionic structure bit.Firstly, this paper probed into the question that how the diameter of bionic unit influences the wear resistance of bionic structure bit, so the four bionic structure bodies having different diameter of bionic unit were designed and manufactured, and then the abrasion ratio were tested. According to the test results, the optimal diameter of bionic unit was selected. And then the arrangement of bionic unit was researched, the two types of arrangement, circular arrangement and uniform arrangement, were designed, and the corresponding bionic structure bodies were manufactured. Secondly, the micro-drilling system was developed, the drilling parameters could be detected, and all bionic structure bodies were tested in the laboratory and the optimal arrangement was selected. At last, by use of finite element software, the coupling model of bionic structure bodies and rock were simulated, and according to the experiment data and simulation results, the wear mechanism of bionic coupling bit was explained. In a word, the conclusions were summarized as followed:First, bionic non-smooth shape on the drilling bit crown is because the bionic units can be worn ahead, so the diameter of bionic unit can decide the diameter of concave. The experiment was made to find the optimal diameter. Four bionic structure bodies having same structure size, same materials and same arrangement were designed and manufactured, after sintered, the abrasion ratios of the four bionic structure bodies were tested. And the results indicates that the abrasion ratio of NO.3 and NO.2 were higher than that of NO.1 and NO.4, and the abrasion ratio of NO.3 is highest, but the difference is about 2% between NO.3 and NO.2. So the optimal diameter of bionic unit is 1.5 mm和2.0 mm.Second, The indoor drilling experiment on the bionic structure bodies shows: not all bionic structure bodies are better than normal diamond bits, except the bionic element arranged in a reasonable range. That means only in that range can the bionic bits have the characteristics of non-smooth anti-wear resistance and drag reduction which can improve the drilling efficiency and durability. The experimental data prove that the arrangement of bionic elements in samples 3#,4#,5#,10#,11#以及16#,17# is more reasonable, which shows the superiority of bionic coupling bit. But generally, uniform arrangement is better than circular arrangement. From the experiment, we know that if the position of bionic element is too close to the boundary of bit can arouse the phenomenon of disconnecting block.Third, the simulation on the bionic structure bodies and 3-D coupling rock model reveals that the friction force of ordinary bit's bottom lip surface is greater than the bionic structure bit when it's rotating. And the bionic region has smaller friction force which reveals the existence of bionic element reduces the resistance of rotating bit. Sample17# data tells that its friction force is the smallest. The equivalent stress on rock of bionic coupling bit is greater than normal Impregnated diamond bit. The 17# bit produced the greatest equivalent stress on rock, which increased 20.50% contrasts to the normal one. The comparison shows that the results of simulation are similar to the experiment's.Four, the reasons of impregnated diamond bionic structure bodies breaking were founded by morphology and spectrum analysis, that is, the good liquid-solid connection was not formed and the materials were oxidized, and it is helpful to improve the matrix performance by use of extending the holding sintering time.Five, the anti-wear mechanism of bionic coupling bit was analyzed from three aspects. The pressure on the crown of bionic coupling bit was improved, which is helpful to make the bit self-sharpness and make the rock produce micro-crack, and the micro-crack was extended. In addition, the concave can store some mud, and that can add the depth of the wetting layer, and all of these is favorable to improve the drilling efficiency. The micro-fluid field can be existed on the crown of bionic coupling bit, as some mud was stored in the concave and the bit was high-speed rotary, which is conducive to the dissemination of friction heat, so the bionic coupling bit was cooling all right. At last, the concave can not only stop the cumulative incidence of scratches, but also ameliorate the stress concentration, which can ensure uniform wear of the bionic coupling bit.Many experiments were made about the diameter and arrangement of bionic unit in this paper, and this will provide the data for manufacturing the bionic structure bit in the future. And based on the optimal diameter of bionic unit, the uniform arrangement as an optimal arrangement was brought forward. In addition, the micro-fluid field was analyzed to explain the anti-wear mechanism of bionic structure bit, and the non-smooth structure is conducive to uniform wear of bionic coupling bit.