Gears are one of the most common and important parts of the organization. Because of its complicated shape, the traditional calculation method can not determine its true stress and deformation distribution law. Therefore, from the perspective of elastic mechanics, the modern design method is used to study the load condition of the gear, which has a wide range of uses, which can improve the whole gear mechanism. The level of design.
In this paper, the numerical analysis software ANSYS is used to analyze the stress and deformation of the driven wheel of a certain semi-axle gear in Tianjin tractor factory. The gear was previously made of 45 steel. If it can be changed to ductile iron material, it will have obvious economic benefits. For this purpose, we give the mechanical model of finite element calculation, calculate the tooth surface contact stress and root bending stress of the gear according to the ANSYS program, and also draw the gear stress distribution map and deformation map to provide the semi-axle gear material. The basis.
2 Establish finite element analysis model 2.1 Gear geometry and material characteristics = 72, modulus m = 6.5mm, displacement coefficient x = 0.27 height coefficient h / = 0.8, head clearance coefficient CX ' = 0 tooth width b = 50mm , full tooth height h = 11.7mm, pressure angle a = 20°. At present, the factory chooses ductile iron QT600-3 as the material to be modified. The parameters of ductile iron are: elastic modulus E = 157GPa Poisson's ratio = 0.27, yield limit s 2.2 The AutoCAD software of the selection model of the calculation model, the model established by AutoCAD can be input into the ANSYS program for analysis. Therefore, this paper first uses AutoCAD to establish the tooth profile of the gear, export the graphics in Iges format, and then use ANSYS import function to import the tooth profile into ANSYS, then perform topology repair and geometric repair on the graphics to complete the modeling work. . Considering the limited transmission range caused by the load on one tooth, we take out 3 teeth and 5 teeth respectively for analysis. After comparison, it is found that the two methods calculate that the tooth root stress difference of the loaded gear teeth is small; Comparing the three tooth thickening with the non-thickening, the difference is also very small. Finally, the three teeth un-thickening model is used for analysis and calculation. As shown: Calculate the load acting on the driven wheel of the semi-axle according to the torque transmitted on the driving wheel of the half-shaft gear: When calculating the bending stress of the root and the contact stress of the tooth surface, the position of the load is different, and the current position is As described below:: 1999-10 1. Ling 1 ((964 female <Tianjin C Institute of Technology I lectured on lectronie 2.3.1 to determine the calculation of the root bending stress when the load position of the gear teeth when subjected to load, the maximum bending moment, Therefore, the bending fatigue strength at the root is the weakest. When the tooth is engaged at the top of the tooth, it is in the two-tooth meshing zone. Although the arm is the largest, the force is not the maximum. Therefore, the highest point of the single-tooth meshing should be found to calculate the tooth. The bending stress of the root. According to the coincidence of the gear mesh = 1.27, the highest point of the single tooth engagement is determined by AutoCAD.
The highest point of single tooth engagement A 2.3.2 determines the position of the load when calculating the contact stress of the tooth surface. It can be seen that the curvature of each point on the involute tooth profile is different, and the load is different at each point along the working tooth profile. Moreover, since the pitting failure generally occurs at the node near the root of the tooth, the contact stress is calculated by meshing at the node. If a concentrated force is applied at the node, the stress in the vicinity of the point of action of the force is large and does not reflect the actual working condition. Therefore, according to the Hertz formula of elastic mechanics, the contact width after elastic deformation of the material is calculated to be 2S=0.64mm. For example, the load is applied to the contact surface of bX2S. For convenience, the Hertz formula is given here: Poisson's ratio of 1P-2 main driven wheel material; EhE2 main driven wheel elastic modulus (MPa) PE comprehensive radius of curvature.
2.4 Dividing the unit to the established calculation model, using the quadrilateral 8-node unit, firstly use the intelligent method to roughly divide the model, and then subdivide it in the vicinity of the node and the root of the tooth, see attached. The tooth root bending stress is calculated according to the plane stress, which is divided into 2873 units and 8 890 nodes. According to the plane strain, the contact stress of the tooth surface is calculated, which is divided into 1 898 units and 5,915 nodes.
2.5 Constraint condition 1 Because the gear diameter is large, the e-load Ai used on the gear teeth is analyzed in the calculation result of the tooth 3. The stress on the surface of the gear is checked as a check, and the tooth tip to the root is calculated according to the material mechanics method. The stress of the intermediate plane DE, where the material mechanics formula can still be approximated, the tensile stress at the D point of the DE plane = 54.237 MPaE, the compressive stress ay=93.87 MPa as shown, according to ANSYS calculation, the town is £100.72 MPa. Through the comparison of the above two calculation methods, it shows that the process calculated by ANSYS has no technical error.
The stress diagram attached to a load step applies the load to the highest point of the single tooth meshing, and calculates the root bending stress according to the plane stress elastic state, and then calculates the Mises stress of the dangerous points on the left and right sides of the gear teeth: “3 yielding The limit indicates plastic deformation. At this point, using the allowable stress method to design, obviously not good. In order to provide more detailed data to the factory, we also changed the design of the ultimate load method: firstly, the dangerous section of the tooth root was calculated by plastic mechanics, and the ultimate load F? 103701N when fully entering the plastic deformation, and then through the elastic and plastic numerical analysis Method, calculate the limit of the dangerous section when fully entering the plastic deformation table 1 1500m3 class bell blast furnace material clock control mechanism parameters foot AB rod is in the upper limit position clock, bucket concentric requirements; the fourth group of parameters for some ironworks in China The parameters of the material control mechanism rods that are optimized and designed are not only ping-pong, but also the IWmax and /(x) values ​​are large. It is also known from the following that the movement path of the material bell hanging point is extremely poor and cannot be satisfactorily satisfied. This institution uses the requirements.
The movement trajectories of the material hook hanging points E obtained from the four sets of parameters in the table are respectively shown in a, b, c, and d, and it is obvious that the movement trajectories a and b of the material hanging points corresponding to the parameters of the first and second groups are compared. Well, the left and right yaw amount is relatively balanced with respect to the center line of the blast furnace, which is favorable for evenly dropping the material into the furnace after the falling of the material clock; the movement track shape of the material hanging point corresponding to the fourth group parameter is not optimized. Poor, the upper and lower positions are biased toward the center line of the blast furnace, which makes it easy to concentrate the furnace material in the furnace.
When the optimized design search is close to the most advantageous, the influence of the parameters t, L, Y on the left and right yaw of the material hanging point is as follows: keep the L and Y values ​​unchanged, and change the value of t has little effect on Hmax, big t The value can be slightly larger, and the I reserve Imax is slightly reduced; the decrease in the t value is reversed. Keeping the values ​​of t and Y) unchanged, the large L value will be comprehensively described. According to the content described in this paper, the optimized design of the blast furnace bell control mechanism can obtain the results that can better meet the requirements of the production process. It is difficult for such institutions to optimize the design to meet the requirements of the production process; some of them are not comprehensive enough to introduce the optimized design content of such institutions, and fail to meet all the requirements of the production process, which is debatable.
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