Abstract: A PDC drill bit has a drill bit body and a blade. The blade is provided with cutting teeth. At least one cushion structure is rotatably connected to the drill bit body. The cushion structure makes contact with bottom hole rock, and the cushion structure swings in a direction opposite to the cutting of the drill bit. Alternatively, a cushioning portion on the cushion structure is eccentrically arranged. Under the action of the normal force of the bottom hole rock, the cushioning portion swings to an offset side. The cushion structure is detached from the bottom hole rock and is reset towards a free state under the action of a reset mechanism. Under complex motion conditions such as compound drilling and drilling into hard or non-uniform stratum conditions, the swing of the cushion structure absorbs an impact load and avoids impact damage to the cutting teeth.

Abstract: The present disclosure provides a method for increasing the bulk density of a nicotinamide mononucleotide crystal and a crystal thereof. The method includes: dissolving nicotinamide mononucleotide in water to obtain an aqueous solution of nicotinamide mononucleotide; performing vacuum concentration or freeze drying on the aqueous solution of nicotinamide mononucleotide to obtain a semi-solid with a water content equal to or less than 15%; adding a solventing-out agent dropwise to the semi-solid under stirring, and meanwhile, performing cooling at a rate of 1-15° C./h to a crystallization end temperature of 5-18° C.; and after a crystal is completely precipitated, performing filtration and drying on the crystal to obtain a nicotinamide mononucleotide crystal with increased bulk density. An NMN crystal of a bulk structure can be prepared by the method, and compared with existing NMN crystals, the bulk density of the NMN crystal is doubled.

Abstract: A torque-adaptive impact tool suitable for a PDC (Polycrystalline Diamond Compact) bit is provided, which includes a PDC bit, a rotary-driving power device, and a torque-adaptive impact tool above the PDC bit. The torque-adaptive impact tool is located between the PDC bit and the rotary-driving power device, includes an outer housing, an upper end cover, a main shaft, an elastic element, an upper impact body, and a lower impact body. In a case of a normal operation of the bit, the tool does not impact the bit, but rotates along with the rotary-driving power device for drilling. In a case that a rock-breaking torque required by the bit exceeds a driving torque, the tool impact the bit.

Abstract: The present application provides an axle box rubber spring including an upper end plate, a lower end plate and a rubber member filled between the upper end plate and the lower end plate, wherein a surface, connected with the rubber member, of at least one of the upper end plate and the lower end plate is provided with a projection and a recess which are distributed alternately, and each of the projection and the recess is in a strip shape. Due to the projection and the recess which are distributed alternatively and both in a strip shape, the axle box rubber spring according to the present application has an increased rigidity, and a reliable positioning is ensured, and further the operating requirement of a heavy-haul railway wagon may be met. The present application further provides a railway wagon bogie having the axle box rubber spring.