Influence of Configuration Error in Bolted Joints on Detection Error of Clamp Force Detection Method

Abstract

Clamp force errors in bolted joints often cause accidents in various mechanical structures. Therefore, the clamp force must be controlled accurately and maintained for securing the reliability of mechanical structures such as vehicles. However, the clamp force cannot be controlled easily during tightening. Moreover, it is difficult to detect the clamp force after tightening. We previously proposed a method to easily detect the clamp force of a bolted joint that has been tightened. In that method, the bolt thread protruding from the nut is pulled while the nut’s upper surface is supported. The relationship between tensile force and displacement at the pulling point where the tensile force is applied differs before and after the tensile force reaches the clamp force. The method detects the tensile force at the point, where the relationship changes, as the clamp force. In this study, we investigate the influence of squareness error on the bearing surface of the clamped part in a bolted joint on the detection error of the method using experiments and finite element (FE) analysis. The experimental results show that the squareness error has an influence on the detection accuracy. The average detection error in the experiments increases by approximately 10% with an increase in the squareness error. To understand the cause of this phenomenon, we investigate the effects of backlash between mating thread surfaces of bolts and nuts on the detection error. The results show that the error decreased because of the backlash. Consequently, it is assumed that the error is caused by the non-separation of the mating thread surfaces when the tensile force reached the clamp force. Furthermore, the FE analysis results show that the squareness error on the bearing surface of the clamped part has an influence of the squareness error on the detection accuracy. The results indicate that we should control the tolerance of squareness errors on the bearing surface of the clamped part when the clamp force detection method is applied to bolted joints.

Influence of Symmetry of Tightened Parts on the Force in a Bolted Joint

“…This measurement is also used to check each bolt pre-tension that assemblers in real conditions when using a torque wrench. Because, as is known e.g., in [20] or in [21], the assembly tightened by the torque control method can vary considerably in the bolt pre-tension achieved, especially in the case of hand tightening. For that reason, many devices have been developed for complex screw fasteners, as for example in [22].…”

“…It has been proven that to achieve the results from Figure 18, the position deviation would have to be significant. The effect of the squareness (flatness) of the bearing surface under the nut to clamp force was previously demonstrated [21]. However, they dealt with force measurement (detection) error in the assembled state or during joint maintenance (after the operation has stopped) in relation to their measurement methodology.…”

“…Other references were crucial in terms of the design and execution of the experiment, e.g., basic information [18] or advanced information from N. Fric [19] about the limitations of strain gauging when using internal strain gauges in bolts. Publications [20][21][22] dealing with the issue of bolt tightening accuracy (achieving bolt preload) were also examined. This information serves mainly to show the scope of the bolted connections issue.…”

A Study of Preload Detection Technology in Suspension Bridge Cable Clamp Bolts Based on the Pull-Out Method

“…Hashimura et al [31] proposed to use the pull-out method to detect the stiffness of the bolt clamping section, but the detected stiffness had a large error compared with the theoretical value. In the study of errors in the pull-out method, Hashimura et al [32,33] discussed the sources of errors in the pull-out method of detection and considered that the verticality of the bearing surface and the thread gap were the main factors causing errors, and found that the pull-out method is highly robust with regard to the verticality error of the bolt-bearing surface.…”

Visual relationship detection method of concrete continuous beam bridge construction scene based on improved ant lion algorithm

“…[8]. Visual relationship detection is a new research direction in recent years [9]. The relationships between objects are semantically related, which makes the appearance of visual relationship detection related to the work of natural language processing.…”