Locking Principle Of Hexagon Nut With Return Difference

Hexagon nut is one of the most common fastener products. Hexagonal nuts look ordinary, but there are many classifications. They are divided into Type 1, Type 2, thin type, positive and negative teeth and other standards. There are also four grades, eight grades, ten grades and twelve grades according to the grade. According to the manufacturing accuracy, it is also divided into A, B and C nuts. Generally speaking, A-type nuts and B-type nuts are used in environments with high requirements, while C-type nuts belong to a relatively rough industry, generally Grade 4 rough nuts, without heat treatment and with natural surface color.

Among them, Type 1 nut refers to the ordinary hexagon nut whose hexagon height is greater than 0.8D, and the corresponding national standard is GB/T6170. Generally, it is of Grade 8 or above. If it is a type 2 nut, it belongs to the standard of thickened nut, which is represented by the national standard GB/T6175. The specification of this thick nut usually starts from M16, and the specifications below 16mm are mainly based on the parameters of GB/T6170. Among the commonly used hexagon nut standards, GB/T41 is the most common grade C nut, grade 4, material Q235, and surface natural color. GB/T6170 is a class A and B nut, class 8 or above, with black or galvanized surface, which is supplied according to requirements and belongs to the most commonly used hexagon nut. GB/T6171 is also a Class A and Class B nut, but it is a fine tooth standard. GB/T6172, 6173 and 6174 all belong to the standard of thin nuts, while GB/T6175 belongs to the thickened nuts, which are 50% thicker than the standard nuts. GB/T6177 is a hexagon flange nut. Although it is also the standard range of hexagon nuts, it is very different from the hexagon nuts we understand in the application environment.

We have roughly understood the materials and standards of hexagon nuts. Now let's take a look at the installation of hexagon nuts. In actual use, the locking effect of one hexagon nut is very poor. In order to achieve a certain locking performance, we can use two identical hexagon nuts at the same time in addition to professional locking nuts. This is achieved by using the return difference principle of double nuts. After two nuts are screwed into the bolt at the same time, the axial force of the front and rear nuts will be limited, so that the front nut cannot be loosened. In order to achieve better results, after screwing in a nut, a washer is added in the middle, and then a nut is screwed in immediately. After the experiment, this anti loosening effect is the best. We can see the following diagram.

In addition to this locking method, we can also achieve it through the pre locking principle of the thread of a round nut against the axial thread. At this time, it is necessary to screw in a round nut first, and then screw in a standard hexagon nut. See the diagram below.

If the round nut cannot be installed at the same time in the actual application environment, we can add a tooth shaped washer to achieve this. Screw in a nut, then add a tooth shaped hot ring, and then screw in a nut. The two facing angles of the tooth shaped washer are different, which limits the tension borne by the two nuts. The following is a schematic diagram.