The chamfered connection between the top of the polished rod part and the bottom surface of the driving head is a further improvement in the hexagonal bolt. As a further improvement, the side wall of the head of the hexagonal bolt can also be provided with anti-skid protrusions, so The protrusions are arranged along the axial direction of the head of the hexagonal bolt.

By setting the drive head in a hexagonal shape, the stability and mechanical strength of the bolt after installation can be improved. At the same time, the length of the polished rod is set to 40% and 60% of the total length of the threaded rod. It is tight, so the stability after fixation is relatively high, but if the polished rod is too long, it is easy to cause difficulty in installation, and the insertion is too shallow. Therefore, according to a large amount of experimental data, determine the length of the polished rod, when it is the total length of the threaded rod. At 409^60%, the stability of the bolt itself in the use state is the highest.

DIN 933 Specifications 

All measurements in millimeters (mm)

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