成型时间决定模拟终止时间。为保证全部成型完成，模拟终止时间应大于成型时

The molding time determines the simulation termination time. To ensure that all molding is completed, the simulation termination time should be greater than the molding time. In order to improve the calculation efficiency and shorten the simulation time, some scholars artificially cut off the simulation termination time and only perform part of the simulation, that is, the extraction of the resulting parameters, called time cutoff. For example, when the initial length and size of the blank and core mold in the prediction model are similar, as the wall thickness decreases and the axial extension of the blank, the actual feed time on the circumference of the core mold will be much shorter than the actual molding time. <br>Through comparison, it is found that the time truncation method is undesirable, which is not conducive to the analysis of the changing trends of the time-dependent results such as wheel force, wall thickness, and axial strain distribution of the element. The strain distribution and strain value of the blank vary with time t, even in the forming zone. Figure 2-6 (a) extracts the change process of the axially distributed units. It can be observed that the deformation process of each unit is long, and it is still affected by the deformation of the surrounding units behind the wheel, which means that the q value changes at any time. In terms of scope, the blank unit is in a continuous deformation state and affects the unit. This process is highly nonlinear. In Figure 2-6 (b), the wheel force curve can also be observed alternately. When studying the variation of wheel force, wall thickness, and axial strain distribution by key parameters such as stagger value, wheel inclination angle, fillet main diameter, feed rate, etc., the simulation end time should not be truncated, which cannot guarantee that the calculation result will reach The final steady state, and the extraction of variational law parameters should be carried out after the entire simulation process.

The molding time determines the simulation termination time. In order to ensure that all molding is complete, the simulation termination time should be greater than the molding time. In order to improve the calculation efficiency and shorten the simulation time, some scholars artificially cut off the simulation termination time, only part of the simulation, that is, the extraction of the result parameters, called time truncation. For example, when the initial length and dimensions of the blanks and core molds are similar in the prediction model, the actual feed time on the circumference of the core die will be much smaller than the actual molding time as the wall thickness decreases and the axial extension of the blanks.<br>Through comparison, it is found that time truncation is not desirable, especially not conducive to the analysis of wheel forces, wall thickness, unit axial strain distribution and other time-sensitive results of the change trend. The strain distribution and strain values of the blanks vary over time, even in the forming area. Figure 2-6(a) extracts the process of axial distribution unit changes, it can be observed that each cell deformation process is long, after the wheel is still affected by the surrounding cell deformation, which means that the q value changes at any time, for the long range, the blank unit in a continuous deformation state, the impact of the unit, the process is highly nonlinear. In Figure 2-6(b), alternating changes in wheel force sweds can also be observed in the wheel force curve. In studying the variation of the variation of wheel force, wall thickness and axial strain distribution of key parameters such as wrong distance value, wheel inclination, fillet main diameter, feed, etc., the simulation end time should not be truncated, which cannot guarantee that the calculation results will reach the final steady state, and the extraction of the variable-rule parameters should be carried out after the whole simulation process.

The molding time determines the simulation end time. In order to ensure the completion of all molding, the simulation termination time should be greater than the molding time. In order to improve the calculation efficiency and shorten the simulation time, some scholars cut off the simulation termination time artificially and only carry out partial simulation, that is, the extraction of result parameters, which is called time truncation. For example, when the initial length and size of blank and core die are similar in the prediction model, with the decrease of wall thickness and the axial extension of blank, the actual feeding time on the core die circumference will be far less than the actual forming time.<br>It is found that the time truncation method is not suitable, especially for the analysis of the variation trend of the wheel force, wall thickness, axial strain distribution and other diachronic results. The strain distribution and strain value of the blank change with time t, even in the forming area. Fig. 2-6 (a) extracts the change process of axial distribution elements. It can be observed that the deformation process of each element is long, and it is still affected by the deformation of surrounding elements after the wheel, which means that the Q value changes at any time. For a long range, the blank element is in a continuous deformation state, which affects the element. This process is highly nonlinear. In Figure 2-6 (b), alternating changes in wheel force can also be observed in the wheel force curve. When the key parameters such as stagger value, wheel inclination angle, fillet main diameter, feed rate and so on are studied to change the distribution of wheel force, wall thickness and axial strain, the end time of simulation should not be cut off, which can not guarantee the final steady state of calculation results, while the extraction of variation rule parameters should be carried out after the whole simulation process.<br>