According to the announcement of the State Intellectual Property Office, Dongfeng Liuzhou Automobile Co., Ltd. applied for an automatic marking device called "an outer hexagonal bolt tightening", the public number CN117464623A, the application date is October 2023.

The patent abstract shows that the invention discloses an automatic marking device for tightening an outer hexagon bolt, which comprises a sleeve and a marking part. The sleeve has a cavity arranged with an opening at one end, and the cavity is used to coordinate with the bolt limit; The marking piece is installed in the cavity through the bearing rotation, and is coaxial with the cavity, and is at least circumferentially fixed with respect to the bearing inner wall, one end of the marking piece is used to connect with the bolt and mark; Wherein, the marking piece is rotated relative to the sleeve to form a circular mark on the bolt surface. In this scheme, the cavity in the sleeve is matched with the bolt in the circumferential direction, and the sleeve is manually rotated to tighten the bolt. Since the marking piece is installed in the cavity through the bearing, the marking piece can rotate relative to the sleeve. During the rotation of the sleeve, the marking piece rotates through inertia, and the bolt is marked with a circle during the rotation process, and automatic marking is realized after tightening.