# Structural Design and Study of an Integrated Cutter System Based on Machine Operation
## 4 Verification of the Anti-Loosening Performance of the Integrated Cutter System
### Experimental Results and Analysis  
After the end of the vibration test, a strain value with time change curve could be obtained. This paper found that the two sides along the axial paste of the three strain gauges of the alignment of the change trend were the same, but there were some differences in the numerical values. For this reason, this paper carried out a detailed analysis of the force on the bolt and found that the bolt does not only bear the axial load. The force analysis of the whole locking system is shown in Figure 15. Firstly, regarding the locking block, it will be subjected to the extrusion reaction force (F\({}_{1}\)) from the shaft of the cutter and the extrusion reaction force (F\({}_{2}\)) from the box, as well as the upward tension force (F\({}_{3}\)) of  
Figure 14: Direction of vibration. Figure 13: Strain gauge placement. the bolt. F\({}_{1}\) can be further decomposed into F\({}_{1x}\) in the horizontal direction and F\({}_{1y}\) in the vertical direction, which form moments with F\({}_{2}\) and F\({}_{3}\), respectively. At this point, in order to balance the resulting torque, the screw will generate force F\({}_{M}\) on the locking block, and, accordingly, the screw will be subject to the reaction F\({}_{M^{\prime}}\) of the locking block, resulting in the bending of both sides of the screw in the direction close to the cutter, which will lead to the strain gauges affixed to S1 and S4 being more pronounced in comparison with the other points. Based on the above analysis, it can be seen that F\({}_{M^{\prime}}\) has an effect on the measurement results of the strain gauges, resulting in the inability to perform a simple averaging of the strain gauges for the same screw. Therefore, this evaluation model was simplified in this paper by comparing the data of six strain gauges in vibration tests with their respective initial values as a way to reduce the influence of F\({}_{M^{\prime}}\) on different strain gauges. Based on the simplified model, each strain gauge can be regarded as a uniaxial loaded state. It can be processed by Equations (5) and (6) to obtain the curve of the preload force with time for the integrated cutter system, where \(E\) is the modulus of elasticity of the material, \(S\) is the cross-sectional area of the screw and \(F\) is the preload force of the screw. \[\varepsilon=\frac{\sigma}{E} \tag{5}\]  
\[\sigma=\frac{F}{S} \tag{6}\]  
In addition, in order to facilitate the analysis of the influence of the vibration direction and the position of the strain gauge paste on the change in the preload force, this paper carried out a normalization process. Taking the initial preload force as a benchmark, the ratio of the residual preload force to the initial force at each moment was calculated, as shown in Equation (7), where \(F_{t}\) is the axial force at moment t and \(F_{0}\) is the initial preload force. \[\eta=\frac{F_{t}}{F_{0}} \tag{7}\]  
After the above processing, the preload variation curve of the integrated cutter sample was finally obtained, as shown in Figure 16.  
Figure 15: Screw force analysis. The following can be seen in Figure 16:  
* The strain gauges pasted at S1 and S4 are the most sensitive to the change in strain information and start to show a significant decrease at the 6 th hour of vibration. The strain gauges at the rest of the locations also show the same trend of change, first gradually decreasing to a certain degree and then stabilizing. This phenomenon is consistent with the loosening trend of the screw and the above analysis of the screw force, which indicates that the strain gauges on the screws can reflect the fastening state of the screws during vibration. * In the first 6 h, at the beginning of the vibration experiment, for the lateral axial load direction vibration, the residual preload ratio and preload curve did not show significant changes. This indicates that the integrated cutter system is not sensitive to vibration in these two directions.