The electromechanical equipment manufacturing plant of Yanzhou Mining (Group) Co., Ltd. has studied the failure modes of polycrystalline diamond compact (PDC) drill bit and related process, and summarized the problems that should be paid attention to during the processing and use of PDC drill bit. The processing level of the drill bit and the extension of the service life have certain reference significance.
(1) The pants body is abnormally worn. The working conditions of PDC drill bits are extremely demanding. As the base of the PDC bit, it must not only have strong comprehensive mechanical properties, but also have good thermal shock resistance and corrosion resistance. The material of the trousers, the processing precision, the heat treatment process and the post-weld grinding are very important. This requires that the material of the trousers should be made of high-quality low-carbon alloy steel such as 42CrMo and 35CrMnSi. The processed trousers should be heat treated accordingly, that is, low temperature tempering after quenching. The surface hardness of the pants body after heat treatment is 40 to 42 HRC, and the structure is tempered martensite.
(2) Blade wear. 1 The diamond layer is separated from the WC base layer. The main reason is that the diamond coating process technology is less mature and stable, and the adhesion between the diamond and the substrate is poor, which causes the diamond film to be peeled off from the WC base layer prematurely, which greatly reduces the service life and cutting performance of the drill bit. The use of titanium powder and diamond micro-powder sintered layer, diamond-like film, tungsten / diamond composition gradient layer and other methods can better eliminate the internal stress caused by the lattice mismatch and the difference in thermal expansion coefficient between the film and the base. 2 macro rupture. The phenomenon is the rupture of the diamond layer. The reason is that the drill bit encounters hard rock or lithological change during the drilling process, and it is subjected to a large alternating impact when it reaches the rock formation, so that the cutting teeth can bear the load in a short time and lead to the drill bit. scrapped. According to the performance of the rig, choose the matching PDC bit to maintain stable drilling pressure and drilling speed during the drilling process, and avoid large impacts as much as possible; improve the bonding force between layers during the material manufacturing process and improve the thermal expansion coefficient between materials. Match and minimize internal stress.
(3) Desoldering. The polycrystalline diamond layer has poor welding process and high control requirements for various parameters. A slight inadvertent can lead to the desoldering of the polycrystalline diamond layer during use. The heating temperature is 760-800 °C, generally silver-based solder, induction brazing or flame brazing is used. The weld strength depends on the structure and state of the material to be joined, the brazing process and the blade and the substrate.

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