Analysis of fluidized hardness of hydraulic frame insert penetrating bolt
The tensile strength limit of the initial condition through bolt is 1100MPa, the yield limit is 935MPa. The elastic modulus is 210GPa, the Poisson's ratio is 0.3. The tightening torque of each bolt is T=2500Nm, the bolt head thread specification is M42×4mm, hydraulic pressure. The maximum oil pressure during hammer operation is p1=16MPa, and the maximum expansion pressure of nitrogen gas is p2=2MPa. Bolt force analysis pre-tightening force calculation The known bolt tightening torque is T=2500Nm, the bolt head thread specification is M42×4mm, and the empirical formula T≈0.2×Qp×d is used to derive the pre-tightening force as Qp=298kN. The calculation of the maximum working load is tightened after the bolt assembly is tightened. When the bolt is subjected to the preload of the oil and gas, the bolt is further elongated, and the body (the nitrogen chamber is in contact with the cylinder) is pressed. There is some slack, so the preload of the body is partially unloaded and becomes the residual preload. Therefore, the maximum load Qmax that the bolt is subjected to is only the sum of the residual preload force Qp' and the working load Fi, or the sum of the preload force Qp and the partial working load ΔF. Rather than a direct superposition of the preload Qp and the working load Fi. That is, Qmax=Qp+XFi(1) where X is the partial load factor, depending on the stiffness ratio of the bolt to the body. Take X=0.2~0.3 when using metal gasket or no gasket, and take X=0.7 when using leather gasket. Take X=0.8 for copper asbestos gasket and X=0.9[6] for rubber gasket. The calculation of the working tension can be calculated according to the working principle of the hydraulic hammer. Rock drilling machine pneumatic tools, 2006 (2) MPa, nitrogen chamber gas maximum expansion pressure is p2 = 2MPa, the total working pressure can be calculated from gas pressure and oil pressure is Fz = p1A1 + p2A2 = p1 × π4 (d21-d2) + p2 × Π4d2=16×π4(1902-1382)+2×π4×1382=244246N When calculating, according to the average force of the four bolts, the working pressure of each bolt is Fi=Fz4=2442464=61061N, here X=0.3 [6]. Substituting the value into equation (1) gives the maximum load Qmax=Qp+X Fi=297.619+0.3×61.061=315.937kN5 Model Establishment and Meshing Considering the symmetry of the bolt structure, we simplify the model and think that the bolt is made by rotating a face 360°. In the analysis process, the model of the rotating surface is established directly in the ANSYN software. The bolt is obtained by rotating the surface around the X axis. When analyzing, it is only necessary to analyze the force of the rotating surface. The established analytical model is shown. In the process of meshing, Solidplane82 is selected as the dividing unit, and the intelligent meshing method is adopted. The level of meshing is set to 5, the meshing of the through bolts is first performed, and then the mesh at the thread is refined and divided. ,. The number of units divided is 7229, and the number of nodes is 22,348. Calculation Solution (1) In the determination of the boundary condition, the degree of freedom in the X and Y directions of the left end face of the bolt is constrained, and the degree of freedom in the Y direction at the X symmetry axis is constrained. (2) The load application experiment shows that the split thread is calculated from the first thread of the thread, and is subject to 1/3, 1/4, 1/5, 1/12, 1/14, 1/16, respectively. The maximum working load is loaded for calculation. After the solution is complete, exit the solution module. Calculation results After the end of the analysis, the bolt deformation is displayed as shown. Then the VonMises stress value on the node is displayed to obtain an equivalent stress cloud map, and the dark color in the stress cloud diagram indicates that the pressure is high. It can be seen from the results that the first ring of the bolt nitrogen chamber side has the largest stress, the largest deformation and the obvious stress concentration. The maximum thread of the thread is the result of the deformation of the bolt thread on the left side is 512 MPa. Conclusion The ANSYS software is used to analyze the strength of the bolts in the hydraulic breaker. The equivalent stress cloud and displacement deformation diagrams of the bolts are obtained. The results show that the first ring of the nitrogen chamber side of the bolt engages the thread, which is the MX shown in the figure. The stress is the largest and the stress concentration is obvious. The maximum stress is 521 MPa, which is less than the yield limit of 935 MPa. U-BOLT: one classice fastener, is widely known and used. Main uses: construction installation, mechanical accessories connection, vehicles and ships, bridges, tunnels and railways, etc usually uesd together with nut.washe. U Bolt,Custom U Bolts,Stainless U Bolts,Stainless Steel U Bolts Taizhou Risco Stainless Steel Products Co.,Ltd , https://www.riscofastener.com
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