| From the11th Five-Year period, Premier Wen Jiabao made important instructions on the decision of the State Council on the geological work, after a period of doldrums, geological exploration began to rebound obviously. Core drilling as one of the main prospecting, there was a period of rapid development. Currently, geological exploration in China has gradually developed in the direction of depth, the rock that deep drilling faces is more and more complex, the diamond drill bit performance requirements are also higher. Traditional methods of manufacturing diamond drill bit are hot-pressing method and electroplating method. Performance of hot-pressing method for manufacturing diamond drill bit is more difficult to control, it is difficult to adapt to deep complex and changeable stratigraphic drilling. Electroplating manufacture of diamond drill bit is often less effective in its internal and external diameter, bits are of low life. So it is difficult to adapt to the complex formation in deep, especially the incomplete stratigraphic and strong abrasive formations for electroplated diamond bit. In addition, the internal structure in working-level of traditional diamond drill bit is relatively homogeneous, diamond and matrix materials inside of the matrix are consistent in a uniform distribution on the work floor performance, leading to the adaptability of the drill bit on the rock is not ideal, greatly reduce a bit of performance. In recent years, scholars, home and abroad, are like to research the new method of braze welding manufacturing diamond tools. Brazing techniques can make the activity of certain elements in the solder and surface carbon atoms in diamond chemical metallurgy reaction occurs, a layer of metal carbide formed on the diamond surface, through this carbide layer, three of diamond, solder and substrate form a strong combination of chemistry and metallurgy. However, it was hard to make impregnated diamond tools by braze-welding method. Currently successful development of brazing diamond tools are single-layer brazed. Diamond tools for ordering the diamond is also a hot research topic in recent years, an ordered arrangement of diamond tools can make full use of each diamond within the tools, diamond consumption thereby reduced, costs reduced. However, because it is difficult to make a template with the ordered arrangement of high-density holes, more orderly arrangement technology in the production of diamond tools for application in low concentrations. Therefore, orderly arrangement technique is often applied to the diamond saw blades, diamond grinding wheels, and other low concentration diamond tools. The purpose of this article is drawing on brazing technology in successful application of monolayer diamond tools, and orderly arrangement technology in low concentrations diamond tools in successful application, hadorwould brazing technology and orderly arrangement technology introduced to geological diamond bit production. Use the specific advantage as high holding force to diamond of the brazing technology to reduce the diamond concentration, at the same time use the orderly arrangement technology to result every diamond in bit in full effect. Eventually developed a high prescription, long life and low cost of new diamond drill bit, to meet the requirements of deep wire-line core drilling in hard rock, and make a positive contribution to the new round of prospecting work.In this paper, basing on the analysis of brazing orderly arrangement diamond bit's performance requirements for filler, diamond and matrix material researches were carried out. Combined with production experience, put to use microanalysis testing technology, material mechanical properties testing technology and simulation technology, etc., then studied the mechanism of filler bond to diamond, the influence of filler composition to matrix performance, matrix material composition between the brazed cutting units, second hot-pressing process, design of ordering array template, and the influence of macro arrangement patterns of diamond in bit to its working performance. After that, selected the primary formula and production technology of brazed multilayer orderly arranged diamond bit, and produced three types diamond bit with different arrangement patterns, and put them up indoor drilling test. As a follow, optimized the diamond bit formula, production technology and macro arrangement patterns of diamond in bit for field drilling test.As brazing diamond bits are fabricated by a new method, according to the new methods requires to the diamond, solder powder and sintering process for the diamond bit, a number of basic researches were done at first in the paper. The diamond in the bit is directly involved in the breaking of rock cut, so diamond is a fine performance has a large impact on drill bit's performance. Impact strength tests on diamond after brazing were done. Result showed that thermal shock resistance as TTI value is61.75%went down near33%than the raw materials of diamond as TI value is91.6%. The diamond used in the manufacture of brazing diamond bit requires a good shock resistance and thermal shock resistance, so the TT value of raw diamond should not be less than80%, and TTI value of not less than75%. In order to prove if there are chemical and metallurgical reactions between solder powder and diamond, surface topography test of diamond after brazing was done, energy spectrum technology was used to test the element generated on the diamond surface. Test indicated that a column of silver-like substance which rich in Cr and C elements generated on the diamond surface. Analysis believe that the active element of Cr in the filler occurred chemical and metallurgical reactions with the C atom from the surface layer of diamond, and the metal carbide on the surface of diamond is the root cause of stronger bonder between filler and diamond. Liquidity test was done on the experimental brazing powder as liquidity of powder directly affects production quality and speed of brazing diamond cutting units. Result showed that liquidity of powder was between14-26s, met the machine requirements of spread powder automatically. But the powder added30%WC relatively has poor mobility, affected of hand-made brazing diamond cutting units speed, while brazing layer properties are not uniform. The solder composition has a large impact on physical and mechanical properties of the matrix. Hardness, flexural strength and wear resistance tests of brazing matrix added WC powder and Fe powder were done in this paper. Results showed that, adding appropriate amount of WC powder can increase hardness and wear resistance of the matrix, but it will reduce the plastic of the matrix, matrix performance best when added in20%.Add the appropriate Fe powder can improve the plastic of matrix, but it will reduce the hardness and wear resistance, matrix performs best when added in30%. In order to prove the internal mechanism of matrix generated physical and mechanical changes by adding metal brazing, metallographic analysis and EDS testing were done on the brazing matrix in the paper. Metallographic analysis showed the second phase of ball and needle-like organizations in matrix added WC powder played an enhanced role of the matrix, hardness and wear resistance of matrix were increased, but the flexural strength of the matrix decreased because of the elastic modulus was different between matrix and WC which played a role in fragmented. There were no globular structure and needle-like organization in the matrix added Fe powder, the disappearance of second phase brittle tissue, making matrix on bending strength increase and yield strength lower, so hardness and wear resistance of matrix decreased. The microscopic spectroscopy tests showed that the gray and black areas of the microstructure in the second phase globular organization and needle-like organization, the area enriched in the elements of Cr, O and B, the possible formation of compounds of CrB and Crx (O) y.In view of the multilayer ordered brazed diamond bit's working conditions and its working layer's functions, wettability between brazing alloy and substrate, brazing process, macro arrangement patterns of diamond in bit, the spacing between diamond grits in the cutting unit, matrix materials used for connecting cutting units, and the second hot-pressing process are all have important influence on bit's performance.In this paper, lower melting point metal such as Cu, Mn has greatly improved the wettability of the solder and matrix. With added Cu, Mn elements in NiCrBSi filler, production of single-layer thin-walled brazed diamond bits were made, with the heating rate of10～15℃/min, heating to the brazing temperature1010℃, holding for10min, cooling to room temperature with rate of10℃/min. Indoor drilling tests showed that aging than electroplated diamond bit and hot diamond bit when drilling granite was increased by46.7%and85.7%, the drill life was increased by33.3%and11.1%. To increase the bit life, brazed impregnated diamond bit was made by conventional mixing material method. It is difficult to arrange the diamond in an orderly way for this drill bit, while the matrix showed high wear resistance, diamond exposed hard during the drilling process, and layer change for diamond was obvious, so the drilling speed decreased. Finally, layering-composite method has been used to fabricate ordering multilayer brazing diamond bit, with thickness of0.2mm stainless steel plate as a brazing substrate. Brazed diamond cutting units are fabricated in accordance with the formulation and process of single-layer thin-walled brazed diamond bit, diamond of each monolayer in the unit were arranged orderly, then overlaid the monolayer brazed diamond cutting units in plural layer according to the law, finally manufactured the multilayer ordered brazing diamond drill bit by secondary sintering process.Diamond with an orderly arrangement helps to reduce the diamond concentration in the drill bit, while can design different concentration and particle size of diamond in the drill bit according to the different working environment. The horizontal distance between diamond particles determines the scope of broken rock, and the longitudinal distance between the brazed diamond layers determines the exposure of diamond in a timely manner. The design of ordering template parameter was in accordance with the rock broken mechanism of impregnated diamond bit, and the horizontal spacing of holes in the template was (2.8-3.1) d, the longitudinal spacing was (1.67-1.9)d, lap height was (1/7-1/3) d, where d was the diamond particle size.Multilayer brazing diamond bit produced by stratification method has three options:cutting units which arranged in concentric with vertical overlay as arcs, in radial with vertical stacking as radials and in fan-shaped with planar overlay as fans. Both finite element simulation of explicit dynamic analysis and indoor drilling tests showed that diamond in bit macro arranged in arcs did better performance than in radials and fans. Analysts believe that, diamond in bit macro arranged in arcs has conductive to the full use of ring fragment body which formed by the rotary bit, using the vibration of the drill bit and forming a bulk broken, and then the rock broken efficiency of bit was improved.According to the explicit finite element dynamic analysis of simulation results and indoor drilling test results, diamond should be macro arranged in arcs in the field drilling diamond bit. The filler formula of diamond bit drilled in hard to strong hard formations with moderate to strong abrasive was determined as NiCrBSi+w (WC)20%; Formula of matrix material bonded cutting units as Ni-21%, Fe-29%, Mn-4%,663-Cu-36%, WC-10%; And then heat the bit to955℃, hold for7min, put on15MPa pressure to the bit simultaneously, steps ahead called secondary hot-pressing process. Twenty eight different specifications of ordinary double tue diamond bits as twenty (p75.5/55mm bits and eight (p56.5/38mm bits, produced by previous formula and process were tested by field drilling in Power plant dam project site in Sichuan, mining area in Fujian, and Pingjiang gold mining area in Hunan. The result was that, the performance of this new bit of multilayer orderly brazed diamond bit compared to the bit with other manufactures used in sites, aging of bit had increased by more than20%, and the bit life had increased by more than20%. For drill of the hard to strong hard stratum with weak abrasive and tight dense, the filler formula was determined as NiCrBSi+w (Fe)30%; Formula of matrix material bonded cutting units as Ni-21%, Fe-39%, Mn-4%,663-Cu-36%; And then heat the bit to950℃holding for7min, put on15MPa pressure to the bit simultaneously. Five φ56.5/38mm ordinary double tue diamond bits, produced with previous formula were tested by field drilling in a site in Dalian. The result was that, compared to the bit site with other manufactures, the performance of these new bits of multilayer orderly brazed diamond bit were well, as aging had increased by38%, but drill life had reduced by27%. Analysts believe that bit with a soft matrix and lower concentration of diamond caused a reduction in bit life. All the tests demonstrated that the development of brazing-hot pressing diamond bit with multilayer ordered brazed cutting units showed a well performance as high aging, long life and wide adaptability.Overall, through a large number of experiments and theoretical analysis, formula and manufacturing technique of Multilayer Orderly-Arranged Brazed Diamond Bit was determined, that is using NiCrBSi for the base brazing material, through bonding metal with secondary sintering process to attach the monolayer cutting units as layered-composite method. Also, the macro arranged mode of diamond in the bit was identified as in arcs. Both brazing technology and orderly arrangement technology were successfully applied to production the geological diamond drill bit which owned better bit performance. The desired goal of using brazing method to manufacturing high-aging, long life, low-cost multilayer ordered geological diamond bit was achieved. Bit makes an increment in the cost of production for the second molding, but the orderly arrangement technical and brazing technique cause diamond consumption for bit greatly reduced, prices of nickel-based brazing filler are also lower than the price of WC powder, Co powder, so the cost of raw materials for bit reduced significantly, then the overall cost of bit was reduced.
|
PDF Full Text Request